LANDFILL LEACHATE TREATMENT USING SUBSURFACE FLOW
CONSTRUCTED WETLANDS ENHANCED WITH MAGNETIC FIELD
NAZAITULSHILA BT RASIT
A project report submitted in partial fulfilment of the
requirements for the award of the degree of
Master of Engineering (Civil – Environmental Management)
Faculty of Civil Engineering
Universiti Teknologi Malaysia
NOVEMBER, 2006
iii
Dedicated to my loved most
Engku Ahmad Rizani
Engku Adam Engku Ahmad Rizani
And
My Family
iv
ACKNOWLEDGEMENT
“In the name of God, the most gracious, the most compassionate”
Firstly, I devote this thesis to my husband and son, Engku Ahmad Rizani and
Engku Adam. Without their love, support, patience and encouragement, my work
would not have been possible. And also for all my family members, especially Mr.
Hj. Rasit and Hjh Nik Kamariah, who are responsible for what I am today.
I wish to extend my sincerest thanks to my Supervisor, Dr. Johan Sohaili for
walking me through the wetland and magnet. Your encouragement for me to do my
own thing, with support, advice and generosity, was forum for a great learning
experience.
I would like to recognize Proffesor Brian Shutes, professor of Ecotechnology
from Middlesex University for providing very useful comments and suggestions. His
vast knowledge in the field of constructed wetlands has assisted me throughout this
thesis project.
Finally, I wish to express my heartfelt thanks to all my colleagues and
environmental laboratories technicians, especially to Pak Usop, En Ramlee Ismail,
En Muzaffar and En Azlan for their timely support during my stay in the
laboratories.
“May Allah bless us with His Taufik and Hidayat. May we benefit from the
knowledge He has given us. May we always be under His Protection and Guidance.
May He forgive us for our sins, those we know and those we do not know. May He
place us on the righteous path and steadfast our Imans. May He shower our one and
true Prohphet Muhammad Alaihisalam and his family and followers, with eternal
blessings. Amin amin, ya rabbal-alamin”
v
ABSTRACT
Leachate is a complex and highly polluted wastewater. Constructed wetlands
are potentially good, low-cost and appropriate technological treatment systems for
treating leachate. Thus, the purpose of this study was to assess the impact of
magnetic field towards the performance of vertical and horizontal subsurface flow
constructed wetland (SSF) vegetated with Limnocharis flava for leachate treatment.
The metals uptake by plants also been investigated. The main parameters evaluation
are total suspended solid (TSS), turbidity, ammoniacal nitrogen (NH4-N), nitrate
(NO3-N), phosphorus and metals (ferum and manganese). Experiments were run in
two systems, which were vertical SSF and horizontal SSF, conducted in duration of
18 days for each. Each of the system consists of control, vegetated and vegetated
with magnet tanks. Results show that the capability of emergent plant in the removal
of all parameters did show a performance compared to unplanted control. Presence of
the vegetation did show there were a substantial removal shown for NH4-N>80%,
NO3-N>70% and heavy metals (Fe>96 and Mn>83%). However, the capability of
emergent plant has lower removal efficiency in TSS (<48%). Constructed wetland
with magnetic field had a greater ability than vegetated treatment in removal of TSS
and metals. For those parameters, highest removal was recorded in both systems
compared to other treatment which was >86% for TSS, complete removal for Fe and
for Mn, removal was >88%. The effect of different flow format used in this study
had shown that vertical flow format do provide a good condition for nitrification but
no denitrification. On the other hand, horizontal flow format cannot provide
nitrification because of their limited oxygen transfer capacity. The treatability of
vertical SSF had showed greater removal in NH4-N (>87%) and Mn (>78%) while
horizontal flow had showed greater removal of NO3-N (>66%). Others parameters
did not contribute to substantial differences between vertical and horizontal SSF
constructed wetlands. The result for metals uptake by Limnocharis flava shows that
the plants leaves and roots are capable to absorb Fe and Mn in leachate.
vi
ABSTRAK
Air larut resap adalah sesuatu yang rumit dan merupakan air sisa yang sangat
tercemar. Tanah bencah buatan berpotensi bagus, berkos rendah dan merupakan
sistem rawatan berteknologi yang sesuai untuk merawat air larut resap. Oleh itu,
kajian ini bertujuan untuk menilai kesan medan magnet terhadap tanah bencah
buatan jenis vertical dan horizontal aliran sub permukaan (SSF) yang ditanam
dengan Limnhocharis flava untuk rawatan air larut resap. Keupayaan tumbuhan
dalam menyerap logam juga dikaji. Parameter utama untuk dikaji adalah pepejal
terampai (TSS), kekeruhan, ammonia nitrogen (NH4-N), nitrate (NO3-N), phosphorus
(P) dan logam (ferum dan manganese). Dua sistem eksperimen telah dijalankan iaitu
vertical SSF dan horizontal SSF yang berlangsung selama 18 hari bagi setiap sistem.
Setiap sistem mengandungi tangki kawalan, tumbuhan dan tumbuhan dengan
magnet. Keputusan menunjukkan keupayaan tumbuhan untuk menyingkirkan semua
parameter berbanding kawalan. Kehadiran tumbuhan menunjukkan penyingkiran
yang banyak bagi NH4-N>80%, NO3-N>70% dan logam (Fe>96 dan Mn>83%).
Walaubagaimanapun, keupayaan tumbuhan untuk menyingkirkan TSS adalah rendah
(<48%). Tanah bencah buatan dengan medan magnet mempunyai kebolehan yang
lebih baik berbanding tanpa magnet dalam menyingkirkan TSS dan logam. Bagi
parameter tersebut, penyingkiran tertinggi telah dicatatkan bagi kedua-dua sistem
berbanding dengan rawatan lain iaitu >86% untuk TSS, penyingkiran semua untuk
Fe dan untuk Mn, penyingkiran adalah sebanyak >88%. Kesan terhadap perbezaan
format aliran dalam kajian ini menunjukkan format aliran vertical menyediakan
keadaan sesuai untuk nitrification dan bukan denitrification. Dengan kata lain, format
aliran horizontal tidak boleh untuk nitrification kerana keupayaan pemindahan
oksigen yang terhad. Rawatan bagi vertical SSF menunjukkan penyingkiran lebih
bagus bagi NH4-N (>87%) dan Mn (>78%) manakala aliran horizontal menunjukkan
penyingkiran lebih bagus bagi NO3-N (>66%). Parameter lain tidak menyumbang
kepada perbezaan penyingkiran yang banyak di antara tanah bencah buatan jenis
vertical dan horizontal. Keputusan keupayaan penyerapan logam oleh Limnocharis
flava menunjukkan daun dan akar tumbuhan berkeupayaan untuk menyerap Fe dan
Mn dalam air larut resap.
vii
TABLE OF CONTENT
CHAPTER
1
2
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
x
LIST OF FIGURES
xii
LIST OF SYMBOLS
xv
LIST OF APPENDIXS
xvi
INTRODUCTION
1.1
Introduction
1
1.2
Problem Statement
2
1.3
Objectives of the Study
3
1.4
Scope of the Study
4
LITERATURE REVIEW
2.1
Introduction
6
2.2
Landfill Leachate
7
2.2.1 Leachate Quantity
8
2.2.2 Leachate Quality
11
2.2.3 Leachate Treatment
14
viii
2.3
2.4
2.5
3
4
Wetland
16
2.3.1 Constructed Wetland
17
2.3.2 Types of Constructed Wetland
18
2.3.3 Wetlands Vegetation
21
2.3.4 Wetlands Function and Values
23
2.3.5 Treatment Processes Mechanisms
24
2.3.6 Treatment Performance
28
Magnet and Magnetism
29
2.4.1 Effect of Magnetic Field to Molecules
33
2.4.2 Magnetic Mechanism
36
2.4.3 Magnetic Treatment
38
Conclusion
41
METHODOLOGY
3.1
Introduction
43
3.2
Leachate Collection
45
3.3
Experimental Set up
45
3.3.1 Magnetic Devices
48
3.3.2
49
Media
3.3.3 Plant
50
3.4
Analysis Procedure
51
3.5
Analysis of heavy metals in plant tissues
51
RESULTS AND DISCUSSION
4.1
Introduction
52
4.2
Treatment Process Mechanisms
53
4.3
Suspended Solid (TSS) Removal
53
4.4
Turbidity Removal
57
4.5
Nutrients Removal
59
4.5.1 Ammoniacal Nitrogen (NH4-N) Removal
59
4.5.2 Nitrate (NO3-N)
62
4.5.3 Phosphorus (P)
64
Metals Removal
68
4.6
ix
5
4.6.1 Ferum (Fe)
68
4.6.2 Manganese (Mn)
71
4.7
ANOVA Analysis
73
4.8
Uptake by Plant
75
4.9
Physical Appearance of Plants
77
4.10
Conclusion
81
CONCLUSIONS
5.1
Conclusions
82
5.2
Recommendations
83
REFERENCES
85
APPENDICES
99
x
LIST OF TABLES
TABLES
TITLE
2.1
Alternative method for management of leachate
2.2
Indications of typical leachate concentrations for various constituents
PAGE
7
in time
8
2.3
Data on the composition of leachate from landfills
9
2.4
Representative biological, chemical and physical processes and
operations used for the treatment of leachate
14
2.5
Important functions and values of natural wetlands
24
2.6
Comparison of different performance constructed wetlands
30
2.7
Summary of magnetic treatment
39
3.1
Description of the plant
50
3.2
Method applied for parameter analysis
51
4.1
Comparison between initial and effluent quality of leachate
53
4.2
Summary of removal mechanisms in wetlands for the pollutants in
wastewater
4.3
Significant differences between control, vegetated and vegetated
with magnet treatment systems for vertical SSF
4.4
73
Significant differences between control, vegetated and vegetated
with magnet treatment systems for horizontal SSF
4.5
54
73
ANOVA analysis comparing vertical and horizontal SSF for control,
vegetated and vegetated with magnet treatment systems
74
4.6
Accumulation of Fe in leaves and roots
77
4.7
Accumulation of Mn in leaves and roots
77
xi
4.8
Amount or partial and complete wilting of plant’s leaves in
vegetated and vegetated with magnet treatment in vertical SSF
constructed wetlands
4.9
78
Amount or partial and complete wilting of plant’s leaves in
vegetated and vegetated with magnet treatment in horizontal SSF
constructed wetlands
78
xii
LIST OF FIGURES
FIGURE
TITLE
PAGE
2.1
Water balance components and direction of leachate to a wetland
10
2.2
COD and BOD5 versus time
12
2.3
Types of constructed wetlands
19
2.4
General arrangement for the constructed wetland with (a) a horizontal
flow and; (b) a vertical flow
20
2.5
Submerged aquatic plants; (a) hydrilla; (b) coontail
22
2.6
Floating aquatic plants; (a) water hyacinth; (b) water lettuce
22
2.7
Emergent aquatic plants; (a) bulrush; (b) cattail; (c) reeds
23
2.8
Right-hand rule
33
2.9
Magnetic field directed out from north pole (N) to south pole (S)
34
2.10
Positioning of fields and force
34
2.11
Nonpolar displacement
35
2.12
Polar displacement
35
2.13
Reaction of charged ion in solution when exposed to magnetic field
36
2.14
Classification of permanent magnet type
37
2.15
Illustration of classes of magnetic devices by installation location
38
2.16
Illustration of classes of non-permanent magnet devices
38
3.1
Flow chart of the experiments
44
3.2
Schematic plan of the SFS system used in the experiments; (a) Control;
(b) Vegetated and; (c) Vegetated with magnet treatment systems
46
3.3
Subsurface flow constructed wetlands for overall experiments
47
3.4
Tank (a) Control; (b) Vegetated; and (c) Vegetated with magnet
47
3.5
Magnetic devices used in the experiment
48
xiii
3.6
Schematic magnetic devices used in the experiments
49
3.7
Cross section of magnetic devices used in the experiments
49
3.8
Limnhocharis flava (yellow burhead)
50
4.1
Suspended solids removal for vertical and horizontal SSF system
55
4.2
Comparison of TSS concentration (C/Co) for; (a) Vertical and;
(b) Horizontal SSF system
56
4.3
Turbidity removal for vertical and horizontal SSF system
57
4.4
Comparison of turbidity concentration (C/Co) for; (a) Vertical and;
(b) Horizontal SSF system
58
4.5
Ammoniacal nitrogen removal for vertical and horizontal SSF system
60
4.6
Comparison of NH4-N concentration (C/Co) for; (a) Vertical and;
(b) Horizontal SSF system
61
4.7
Nitrate removal for vertical and horizontal SSF system
63
4.8
Comparison of NO3-N concentration (C/Co) for; (a) vertical and;
(b) horizontal SSF system
64
4.9
Phosphorus removal for vertical and horizontal SSF system
65
4.10
Comparison of P concentration (C/Co) for; (a) vertical and;
(b) horizontal SSF system
67
4.11
Ferum removal for vertical and horizontal SSF system
69
4.12
Comparison of Fe concentration (C/Co) for; (a) vertical and;
(b) horizontal SSF system
70
4.13
Manganese removal for vertical and horizontal SSF system
71
4.14
Comparison of Mn concentration (C/Co) for; (a) Vertical and;
(b) Horizontal SSF system
Fe uptake by root and leaves for (a) vertical and; (b) horizontal SSF
72
4.15
system
75
4.16
Mn uptake by root and leaves for (a) vertical and; (b) horizontal SSF
system
4.17
Physical appearance of plants in (a) vegetated and; (b) vegetated with
magnet after 6 days of treatment in vertical SSF
4.18
78
Physical appearance of plants in (a) vegetated and; (b) vegetated with
magnet after 12 days of treatment in vertical SSF
4.19
76
79
Physical appearance of plants in (a) vegetated and; (b) vegetated with
magnet after 18 days of treatment in vertical SSF
79
xiv
4.20
Physical appearance of plants in (a) vegetated and; (b) vegetated with
magnet after 6 days of treatment in horizontal SSF
4.21
Physical appearance of plants in (a) vegetated and; (b) vegetated
with magnet after 12 days of treatment in horizontal SSF
4.22
79
80
Physical appearance of plants in (a) vegetated and; (b) vegetated
with magnet after 18 days of treatment in horizontal SSF
80
xv
LIST OF SYMBOLS
B
-
Magnetic field
BOD
-
Biochemical Oxygen Demand
CaCO3
-
Calcium carbonate
COD
-
Chemical Oxygen Demand
F
-
Magnetic field force
Fe
-
Ferum
FWS
-
Free Water Surface
HF
-
Horizontal flow
I
-
Current
mg/g
-
milligram per gram
mg/L
-
milligram per liter
mL/s
-
milliliter per second
Mn
-
Manganese
NH4-N
-
Ammoniacal Nitrogen
NO3-N
-
Nitrate
P
-
Phosphorus
SSF
-
Sub Surface Flow
TSS
-
Total Suspended Solid
TOC
-
Total Organic Carbon
TDS
-
Total Dissolved Solids
TKN
-
Total Kjeldahl-N
TN
-
Total Nitrogen
TP
-
Total Phosphorus
VF
-
Vertical Flow
VFA
-
Volatile Fatty Acids
VSB
-
Vegetated Submerged Bed
XOC
-
Xenobiotic Organic Compound
xvi
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
Raw Data
99
B
Varian Analysis Calculation (ANOVA)
104
CHAPTER 1
INTRODUCTION
1.1
Introduction
The mass of solid waste produced globally is increasing at a rapid pace.
Although improvements are being made in reducing, reusing and recycling of waste,
protecting the environment and human health continues to be a challenge. One of the
major consequences of rapid economic growth, urbanization, industrialization and
population growth is the massive generation of solid wastes. As a country that
moving forward to achieve the industrialized country status by the year 2020,
Malaysia is grappling with solid waste management problems. The solid waste
disposal method in Malaysia is solely landfill. Other methods such as incineration
and composting are at an imperceptible scale. The municipal solid wastes in
Malaysia that have gone for landfilling is approximately 95% and only 5% are
recycled. Even though there is a huge amount of municipal solid waste that goes to
landfill, the landfilling practice in Malaysia is far from environmentally sounded.
According to Ministry of Housing and Local Government Malaysia (1999), out of
177 landfills in Peninsular Malaysia, estimated only 6% are sanitary landfills, 44%
are control tipping landfill and 50% are crude dumping sites.
2
However, leachate production when water is allowed to come in contact with
the waste and generation of gases from biodegradation of the waste at landfill sites
may cause environmental pollution (Wilson, 1981). Leachate is a liquid consisting of
moisture generated from landfill during the waste degradation process. When
leachate is produced and moving inside the landfill, it picks up soluble, suspended or
miscible materials removed from such waste (Corbitt, 1994). Leachate has high
content of iron, chlorides, organic nitrogen, phosphate and sulphate (Preez and
Pieterse, 1998). When this highly contaminated leachate leaves landfill and reaches
water resources, over time, it will cause surface water and ground water pollution.
The contamination of water is affecting with the human body and environment.
The high strength of wastewater characteristics in leachate makes it difficult
to treat by itself thus biological wastewater treatment technologies can be adapted for
treatment of leachate. The technology for treatment and pretreatment of leachate
include wetlands treatment. These systems employ natural or man-made
(constructed) wetlands systems that treat wastewater utilizing natural processes of
sedimentation, adsorption and organic degradation (Corbitt, 1994).
Application of constructed wetlands is significant because the wetlands have
often been assumed to possess a specific capacity to absorb and retain particulate
matters, nutrients or other pollutants which enters water bodies through surface
runoff, domestic wastewater, and industrial wastewater and also from plantations
(Hughes et al, 1992). Besides constructed wetlands are used to treat wastewater
(Brix, 1994) and leachate from landfills (Wittgren and Maehlum, 1997; Robinson,
1990; Staubitz et al., 1989; Surface et al., 1993), wetlands are also used in the
treatment of industrial waste from textile industries and food processing industries.
1.2
Problem Statement
There is a lack of proper leachate collection and treatment in developing
countries including Malaysia. The majority of the landfills in Malaysia are without
leachate collection and treatment facilities. A regional survey on 30 local authorities,
3
only 4 out of 69 landfills being surveyed have leachate collection (Nasir et al, 1998).
There is a lack of leachate and an impermeable liner system in most landfill ,
leachate will easily leach out and contaminate the nearby water. With respect to the
environment, this situation should be changed. Due to the financial situation and to
the more stringent standards, leachate treatments are much more developed in
industrialized countries (Aslam et al., 2004). High technology leachate treatment
systems are often avoided because of high cost of construction and operation. An
alternative is cost efficient natural treatment systems such as constructed wetlands
for secondary or tertiary treatment, due to their characteristic properties including
simple construction, simple operation and maintenance, process stability and cost
effectiveness (Surface et al., 1993; Lin et al., 2002). Hence, the potential to expand
the use of constructed wetlands to the treatment of leachate is relevant in today’s
context.
Constructed wetland technologies have already shown good results in treating
wastewater. Wetland treatment of landfill leachates has been successfully tested at
several locations. Reed beds are used to treat leachate in United Kingdom (Robinson,
1990) and a facility at Ithaca, New York has utilized SSF wetlands and has been
operating since 1989 (Staubitz et al., 1989; Surface et al., 1993). Although,
constructed wetland using magnetic technology is a relatively new idea in Malaysia
and the potential of magnets has not yet been discovered. Increasing research and
knowledge of wetland have led to the trend to construct wetlands enhanced with
magnetic field that obviously duplicate the environmental friendly benefit to the
ecosystem. Therefore, this study was carried out to study the effectiveness of a
magnetic field to leachate treatment using subsurface flow constructed wetland (SSF)
planted with Limnocharis flava.
1.3
Objectives of the Study
The aim of this study is to investigate the feasibility of applying subsurface
flow constructed wetlands (SSF) treatment process enhanced with magnetic field.
The objectives of the study are:
4
(i)
To investigate the capability of an emergent plant (Limnocharis flava)
with and without magnetic field for the removal of ammonia nitrogen,
nitrate nitrogen, phosphate, ferum, manganese, SS and turbidity in
treating landfill leachate using constructed wetland;
(ii)
To evaluate the treatability of vertical subsurface flow (VF) and
horizontal subsurface flow (HF) constructed wetland;
(iii)
To determine the heavy metal (Fe and Mn) uptake by Limnocharis
flava in roots and leaves.
1.4
Scope of the Study
Increasing research and knowledge of the role of natural wetlands in
controlling water pollution have led to the trend to construct wetlands that duplicate
the environmental benefit to the ecosystem. Hence, the following criteria will form
the principal for the scope of the study:
(i)
There were two systems performing subsurface flow constructed
wetlands (SSF) and each system was operated for a period of 18 days.
The first system was conducted as vertical flow (VF) while the second
system was horizontal flow (HF) constructed wetlands;
(ii)
Each system contained 3 tanks. Tank A was not planted for control
purposes whilst tanks B and C were planted with 8 clusters of
Limnocharis flava. In addition, sample discharged from tank C was
treated with magnetic field for 6 hours;
(iii)
The vegetation species that was used in this study is Limnocharis
flava;
5
(iv)
Six sets of permanent magnet with 0.55 Tesla was used in the
experiment;
(v)
The efficiency of leachate treatment for each system was evaluated
for ammonia nitrogen, nitrate nitrogen, phosphate, ferum, manganese,
SS and turbidity. HACH DR/4000 spectrophotometer equipment was
used for analysis of each parameter;
(vi)
Heavy metal (Fe, Mn) by plant uptake are two components which
were investigated by looking at the concentration in plant leaves and
roots;
(vii)
All experiments were carried out in Environmental Engineering
Laboratory, Faculty of Civil Engineering, Universiti Teknologi
Malaysia.
CHAPTER 2
LITERATURE REVIEW
2.1
Introduction
Landfill is utilized as one of the significant methods to manage solid wastes
among other disposal method. This scenario is widespread and will continue for the
envisage future. In spite of the low capital cost and low expertise is needed when
compared to other disposal or treatment methods, landfill can accept all sorts of
waste (Ridhuan, 1995). Other treatment methods such as composting, incineration,
pyrolysis and biogastification can significantly reduce the waste volume and can
recover resources during the treatment process, but they will always have some
residual left for final disposal at the landfill. In countries such as Japan and
Switzerland where the incineration rate is high, 74% and 80% respectively
(Agamuthu, 2001), landfill is still needed as the ultimate disposal method.
Hence, the matters of concern are the consequences of the past and ongoing
use of landfills because of the potential for possess negative impacts to the
environment. Landfill is a complex system. Hence, the incentive for comprehensive
control strategies must be developed, which are now used in current landfill designs.
These control strategies have included the implementation of leachate collection
systems. If the landfilling could be carried out in a proper manner coupled with
well-managed solid waste and leachate collection and transportation system, this
7
would form the very fundamental level for the solid waste management (Rylander,
1998). However, leachate collection must be dealt as part of the long-term
commitment for solid waste management (McBean and Rovers, 1999). And once the
collection of the leachate has become part of a solid waste management system, a
series of leachate treatment options must be examined. The potential alternative
methods for the management of landfill leachate are shown in Table 2.1. Wetlands
provide a useful natural treatment system, either for from old wastes or for partial
treatment of leachates from newer wastes.
Table 2.1: Alternative method for management of leachate
(McBean and Rovers, 1999)
Alternative Method
Spray irrigation on adjacent grassland
Recirculation of leachate through the landfill
Disposal off site to sewer for treatment as an admixture with domestic sewage
Physical-chemical treatment
Anaerobic biological treatment
Aerobic biological treatment
Wetlands
2.2
Landfill Leachate
Leachate is the liquid that has passed through or emerged from solid waste
and contains dissolved, suspended, or immiscible materials removed from the solid
waste (Tchobanoglous et al., 1993). The characteristics of leachate vary with the age
of the landfill (Paredes, 2003; Baig et al., 1999) and the material placed in the
landfill (Wilson, 1981). The composition of the leachate will depend on the
heterogeneity and composition of the waste. For biodegradable wastes, the stage of
biodegradation reached by the waste, the moisture content and the operational
procedures will vary the composition of the waste (Kjeldsen et al, 2002). According
to McBean and Rovers (1999), factors that influence leachate composition include
waste type and composition, waste density, pretreatment, placement sequence and
depth, moisture infiltration, ambient air temperature, landfill management practices
and time. Typical leachate concentrations for an array of constituents are shown in
8
Table 2.2. Since all sanitary landfills generate leachate and since leachate may
migrate from the waste and contaminate the surface water and groundwater (Paredes,
2003), collection and treatment of leachate is a necessary part of the overall facility
(Wilson, 1981).
Table 2.2: Indications of typical leachate concentrations for various
constituents in time (McBean and Rovers, 1999)
Constituent
BOD
TKN
Ammonia-N
TDS
Chloride
Sulfate
Phosphate
Calcium
Sodium and Potassium
Iron and Magnesium
Aluminium and Zinc
2.2.1
1 Year
20,000
2,000
1,500
20,000
2,000
1,000
150
2,500
2,000
700
150
Concentration (mg/L)
5 Years
15 Years
2,000
50
400
70
350
60
5,000
2,000
1,500
500
400
50
50
900
300
700
100
600
100
50
-
Leachate Quantity
Rainwater falling directly on the landfill and off-site stormwater flowing
across the site are the major source of water for leachate generation (Lu et al., 1980;
Wang, 2004; Wilson, 1981). Chemical and biological reactions occur when
infiltrating water percolates through wastes (Kouzeli-Katsiri et al., 1999; Wang,
2004). The ongoing reactions within the waste will produce complex combination
and transport by the infiltrating water. Besides the chemical and biological reactions,
physical processes such as sorption and dissolution also take place during the
passage of water through the waste (McBean and Rovers, 1999). Leachate has high
content of iron, chlorides, organic nitrogen, phosphate, sulphate (Preez and Pieterse,
1998) and high in organic matters and inorganic ion concentrations (Uygur, A. and
Kargi, F., 2004). Typical data on leachate composition are illustrates in Table 2.3.
Leachate generation is induced by precipitation. It is also produced as a result
of biochemical processes that convert solid materials to liquid form. The leachate
9
generated from the biochemical reactions is characterized by very high
concentrations of organic and inorganic contaminants (McBean and Rovers, 1999).
Bagchi (1990) states that water percolating through the landfill surface from
infiltration will actually dilute contaminants in the leachate, as well as aid in the
formation of new leachate.
Table 2.3: Data on the composition of leachate from landfills
(Tchobanoglous et al, 1993)
Constituent*
BOD5 (5-day Biochemical Oxygen Demand)
TOC (Total Organic Carbon)
COD (Chemical Oxygen Demand)
Total Suspended Solids
Organic Nitrogen
Ammonia Nitrogen
Nitrate
Total Phosphorus
Ortho Phosphorus
Alkalinity as CaCO3
pH
Total hardness as CaCO3
Calcium
Magnesium
Potassium
Sodium
Chloride
Sulfate
Total Iron
Range
2000-30,000
1500-20,000
3000-45,000
200-1000
10-600
10-800
5-40
1-70
1-50
1000-10,000
5.3-805
300-10,000
200-3000
50-1500
200-2000
200-2000
100-3000
100-1500
50-600
Typical
10,000
6000
18,000
500
200
200
25
30
20
3000
6
3500
1000
250
300
500
500
300
60
*All units in milligrams per liter except pH.
The temporal variability of leachate quantities and qualities is influenced by
features including the meteorology, the cover overlying the waste, the vicinity of the
site, and numerous characteristics of the waste such as age, composition and degree
of compaction (McBean and Rovers, 1999). The features of water balance, such as
precipitation, interception and surface runoff, evapotranspiration by vegetation and
infiltration at a landfill site, are schematically depicted in Figure 2.1.
In Malaysia, solid waste composition reported by Agamuthu (2001) is mainly
organic in nature and has high moisture content at about 75%. These waste
characteristics have caused more leachate being produced than inorganic waste with
low moisture content. The annual precipitation in Malaysia ranges from 2000mm to
10
2500mm and the heavy rainfall precipitation have further increased leachate
production.
Interception and
Evapotranspiration by
Vegetation
Precipitation
Infiltration
Surface Runoff
Moisture Content of waste at
time of placement
Leachate Collection
Tiles
Wetland
Figure 2.1: Water balance components and direction of leachate to a wetland
(McBean and Rovers, 1999)
2.2.2
Leachate Quality
The characteristics of the leachate are influenced by the waste material
deposited in the site. For example, inert wastes will produce a leachate with
concentrations of components, whereas a hazardous waste leachate tends to have a
wide range of components with highly variable concentrations. The decomposition
rate of the waste also depends on aspects such as pH, temperature, aerobic or
anaerobic conditions and the associated types of micro-organism. Associated with
leachate is a malodorous smell, due mainly to the presence of organic acids
(Williams, 2005).
The toxicity of leachate based on bioassay testing of leachate with various
organisms has reported high toxicity levels in leachate, derived from municipal solid
11
waste landfills (Kjeldsen et al 2002). Several studies of leachate toxicity report that
ammonia, chloride, acidity or alkalinity and heavy metal concentrations are the main
toxic pollutant in landfill leachate. It has also been suggested that leachate from
municipal solid waste landfill sites may be mutagenic and carcinogenic (Kjeldsen et
al, 2002).
The pollutants found in leachate from municipal solid waste landfill sites can
be broadly categorized into four main groups (Kjeldsen et al, 2002):
(i)
Dissolved organic material (COD and TOC), volatile fatty acids and
fluvic and humic-like material;
(ii)
Inorganic macrocomponents including calcium, magnesium, sodium,
potassium, ammonium, iron, manganese, chloride, sulphate and
bicarbonate compounds;
(iii)
Heavy metals such as cadmium, chromium, copper, lead, nickel and
zinc compounds;
(iv)
XOC which are compounds not degraded by organisms in the
environment and include aromatic hydrocarbons, pesticides,
plasticizers, chlorinated aliphatic compounds, etc. These compounds
originate from household and industrial chemicals and are present in
low concentrations.
A series of phases is detectable in the decomposition of solid waste (Figure
2.2). Phase I known as the hydrolysis and acidification phase, involving aerobic
decomposition, is typically brief, and lasts for less than a month. Once the available
oxygen within the waste is utilized, except in the vicinity of the landfill surface,
aerobic decomposition terminates (McBean and Rovers, 1999).
12
Figure 2.2: COD and BOD5 versus time (McBean and Rovers, 1999)
Phase II known as initial methane generation phase, begins with the initiation
of activities of anaerobic and facultative organisms (involving acetogenic bacteria).
They hydrolyze and ferment cellulose and other putrescible materials, producing
simpler, soluble compounds such as VFAs (which produce a high BOD value) and
ammonia. Phase II can last for years, or even decades. Leachates produced during
this stage are characterized by high BOD values which commonly greater than
10,000 mg/L and high ratios of BOD to COD (commonly greater than 0.7),
indicating that high proportions of soluble organic materials are readily
biodegradable. Other typical characteristics of phase II leachates are acidic pH levels
(typically, 5 to 6), strong, unpleasant odors, and high concentrations of ammonia, in
the range of 500 to 1000 mg/L. The aggressive chemical nature of this leachate
assists in dissolution of other components of the waste, and produces high levels of
iron, manganese, zinc, calcium, and magnesium in the leachate (McBean and Rovers,
1999).
Phase II also involves slower-growing methanogenic bacteria gradually
becoming established and consuming simple organic compounds, with the
production of a mixture of carbon dioxide, methane, and other trace gaseous
13
constituents that constitute landfill gas. The transition from phase II to phase III
decomposition can take many years, may not be completed for decades, and is
sometimes never completed (McBean and Rovers, 1999).
In phase III, bacteria gradually become established that are able to remove the
soluble organic compounds, mainly fatty acids, which are largely responsible for the
characteristics of phase II leachates. There is a depletion of both COD and BOD over
time in phase III (McBean and Rovers, 1999).
Leachates generated during phase III are often referred to as “stabilized,” but
in the life cycle of a landfill at this stage the landfill is biologically at its most active
level. A dynamic equilibrium is eventually established between acetogenic and
methanogenic bacteria, and wastes continue to actively decompose. Leachates
produced during phase III are characterized by relatively low BOD values and low
ratios of BOD to COD. However, ammonia nitrogen continues to be released by the
first-stage acetogenic process and will be present at high levels in the leachate.
Inorganic substances such as iron, sodium, potassium, sulfate and chloride may
continue to dissolve and leach from the landfill refuse for many years (McBean and
Rovers, 1999).
The composition of phase III leachate is characterized by neutral pH levels,
strongly reducing redox potential, low concentrations of VFAs and higher
concentrations of refractory organic matter. The methanogenic phase is the longest
and most important phase of waste stabilization, with phases 1V and V occurring as
the refuse becomes depleted of degradable organics (McBean and Rovers, 1999).
2.2.3
Leachate Treatment
Leachate is often so polluted. Thus, available leachate treatment should be
evaluated to be treated before it can be passed into a sewer or receiving water course.
Table 2.4 indicates operations used for the treatment of leachate.
14
Table 2.4: Representative biological, chemical and physical processes and
operations used for the treatment of leachate (Tchobanoglous et al., 1993)
Treatment Process
Biological processes
Application
Comments
Activated sludge
Removal of organics
Defoaming additives may be necessary;
separate clarifier needed
Sequencing batch
reactors
Removal of organics
Similar to activated sludge, but no
separate clarifier needed; only
applicable to relatively low flow rates
Aerated stabilization
basins
Removal of organics
Requires large land area
Fixed film processes
(trickling filters,
rotating
biological contactors)
Removal of organics
Commonly used on industrial effluents
similar to leachates, but untested on
actual landfill leachates
Anaerobic lagoons
and contactors
Removal of organics
Lower power requirements and sludge
production than aerobic systems;
Requires heating; greater potential for
process instability;
Slower than aerobic systems
Nitrification/
denitrification
Removal of organics
Nitrification/denitrification can be
accomplished simultaneously with the
removal of organics
Neutralization
pH control
Of limit applicability to most leachates
Precipitation
Removal of metals
and some anions
Produces sludge, possibly requiring
disposal as a hazardous waste
Oxidation
Removal of
organics;
detoxification of
some inorganic
species
Works best on dilute waste streams; use
of chlorine can result in formation of
chlorinated hydrocarbons.
Wet air oxidation
Removal of organics
Costly; works well on refractory
organics
Removal of
suspended matter
Of limited applicability alone; may be
used in conjunction with other
treatment processes.
Chemical processes
Physical operations
Sedimentation/
flotation
15
Treatment Process
Filtration
Application
Removal of
suspended matter
Comments
Useful only as a polishing step
Air stripping
Removal of
suspended matter
May require air pollution control
equipment
Steam stripping
Removal of volatile
organics
High energy costs; condensate steam
requires further treatment
Adsorption
Removal of organics
Proven technology; variable costs
depending on leachate
Ion exchange
Removal of
dissolved inorganic
Useful only as a polishing step
Ultrafiltration
Removal of bacteria
and high molecular
weight organics
Subject to fouling;
Limited applicability to leachate
Reverse osmosis
Dilute solutions to
inorganic
Costly;
Extensive pretreatment necessary
Evaporation
Where leachate
discharge is not
permissible
Resulting sludge may be hazardous;
Can be costly except in arid regions
Some forms of pretreatment or complete treatment as previously shown in
Table 2.4 are required when leachate recycling and evaporation is not used and the
direct disposal of leachate to a treatment facility is not possible. The problem with
leachate treatment is that leachate changes in terms of strength, biodegradability, and
toxicity as the wastes in the landfill age over time. The treatment process or
processes selected will depend to a large extent on the contaminants to be removed.
2.3
Wetland
The word "wetland" by itself conveys mixed meanings. One of the earliest
definitions of the term natural wetlands was presented by the U.S. Fish and Wildlife
Service in 1956 (Shaw and Fredine, 1956):
“Wetlands” refers to lowlands covered with shallow and sometimes
temporary or intermittent waters. They are referred to by such names as
16
marshes, swamps, bogs, wet meadows, potholes, sloughs, and riveroverflow lands. Shallow lakes and ponds, usually with emergent
vegetation as a conspicuous feature, are included in the definition, but
the permanent waters of streams, reservoirs, and deep lakes are not
included.
Perhaps the most comprehensive definition of wetlands was adopted by
wetland scientists in the U.S. Fish and Wildlife Service in 1979, after several years of
review. The definition was presented in a report entitled Classification of Wetlands
and Deepwater Habitats of the United States (Cowardin et al., 1979):
“Wetlands are lands transitional between terrestrial and an aquatic
system where the water table is usually at or near the surface or the land
is covered by shallow water. Wetlands must have one or more of the
following three attributes: (1) at least periodically, the land supports
predominantly hydrophytes, (2) the substrate is predominantly undrained
hydric soil, and (3) the substrate is nonsoil and is saturated with water or
covered by shallow water at some time during the growing season of
each year”
Wetlands vary widely because of regional and local differences in soils,
topography, climate, hydrology, water chemistry, vegetation, and other factors,
including human disturbance (USEPA, 1983). Water saturation (hydrology) largely
determines how the soil develops and the types of plant and animal communities
living in and on the soil.
2.3.1 Constructed Wetland
Constructed wetland is a water treatment facility duplicating the processes
occurring in natural wetlands. In natural system, the processes occur at “natural”
rates however, constructed wetland introduced by USEPA (1993) is defined as a
wetland specifically constructed for the purpose of pollution control and waste
17
management, at a location other than existing natural wetlands. Duplicating the
processes occurring in natural wetlands, constructed wetlands are complex,
integrated systems in which water, plants, animals, microorganisms and the
environment; sun, soil and air interact to improve water quality. The systems are
designed to maximize the physical, chemical and biological abilities of natural
wetlands to reduce the BOD, TSS, TN, P and pathogens as wastewater flows slowly
through the vegetated subsurface. Bioaccumulation, biotransformation and
biodegradation of metals are also possible (Kadlec and Knight, 1996). The
mechanisms of pollutant removal include both aerobic and anaerobic microbiological
conversions, sorption, sedimentation, volatilization and chemical transformations
(Aslam et al., 2004; Robert, 1999; Vymazal, 2005a).
In 1970s and 1980s, constructed wetlands were nearly exclusively built to
treat domestic or municipal sewage. Since 1990s, the constructed wetlands have been
used for all kinds of wastewater including landfill leachate, runoff (e.g. urban,
highway, airport and agricultural) (Tanner et al, 1995a; Kern and Idler, 1999), food
processing (e.g. winery, cheese and milk production), industrial (e.g. chemicals,
paper mill and oil refineries) (Mays and Edward, 2001; Panswad and Chavalparit,
1997), agriculture farms, mine drainage or sludge dewatering (Bastian et al, 1989;
Vymazal, 2005a) and stormwaters (Carleton et al, 2000; Wong et al, 1995). The use
of constructed wetlands has several advantages over conventional wastewater
treatment methods. The initial cost of constructed wetlands is considerably lower
than conventional treatments (Aslam et al., 2004; Kadlec and Knight, 1996). While
constructed wetlands efficiently remove many pollutants from wastewater streams,
constructed wetlands also enhance the environment by providing a habitat for
vegetation, fish, birds, and other wildlife (Aslam et al., 2004; Bays et al, 2002).
Both constructed and natural wetlands are being used at an increasing rate for
treatment of wastewaters because of their consistent performance for pollutant
removals. Knight (1997) reported that wetlands degrade most forms of organic
matter to carbon dioxide and release trace elements in the process. Both particulate
and soluble forms of BOD compounds are trapped and degraded in wetlands.
Potentially toxic metals associated with particulate matter and soluble metals in ionic
or complexed form are trapped and retained to varying degrees by the complex
18
biology and chemistry of treatment wetlands. Some organics are only slightly
modified and may remain in a treatment wetland in a biologically toxic form for an
indefinite time period.
2.3.2
Types of Constructed Wetlands
Constructed wetlands for wastewater treatment are classified by the flow path
of the water in the system (Reed, 1988) as Figure 2.3, which is free water surface
(FWS) and subsurface flow system (SSF) (Hammer, 1989; Kent, 1994). Both FWS
and SSF systems are characterized by emergent vegetation. This study is concerned
with the SSF wetland type.
FWS consist of basins or channels and barriers such as constructed clay layer
or geotechnical material to prevent seepage (Lim et al., 1998), and have relatively
shallow water depths and low flow velocities. The water surface is exposed to the
atmosphere, and the intended flow path through the system is horizontal. In FWS,
water flows over the soil surface from an inlet point to an outlet point or in a few
cases is totally lost to evapotranspiration and infiltration within the wetlands. It is
said to have properties in common with facultative lagoons and also to have some
important structural and functional differences. In free water surface flow wetlands
the surface layer is in aerobic condition whereas the deeper water and substrate are
usually anaerobic. Some disadvantages of FWS system are larger land area is
required and the water is easily exposed to human environments. Mosquito problems
are also arising in the operation of FWS that breed easily in the water.
Subsurface flow systems (SSF), sometimes called vegetated submerged bed
systems (VSB), consist entirely of subsurface flow conveyed to the system through a
trench or bed underdrain network that contain suitable depth of porous media. As
with FWS systems, they have barriers to prevent seepage and very low flow
velocities. The wastewater will flow in a high level site of the wetland and then flow
through the porous media of sand soil and plant rhizosphere. The wastewater is treated
by the physical-chemical and biochemical complex processes of filtration, sorption and
19
precipitation processes in the soil and by microbiological degradation. Finally, the
treated wastewater flows out in the bed that remains below the top of the porous media.
Types
Free Water Surface System
Subsurface Flow System
Diagram
Water Level Above ground surface
Below ground
Water Flow
Above ground
Through soil or gravel
Vegetation
Planted or colonized
Common reed, bulrush or cattail
Plants
Rooted and emergent
To bottom of bed
Figure 2.3: Types of constructed wetlands (Robert, 1999)
The SSF wetland types have several advantages if compared with the FWS
wetland types. It is found that in the SSF system, the available through wastewater
treatment is better than the constructed FWS one. Wastewater flowing subsurface media
may also avoid of the little risk of heavy odors, dark-color exposure and insect vectors
effects. The area application for SSF wetland can be smaller than a FWS system with the
same wastewater withdraw conditions. Constructed soil-and gravel based in SSF
wetlands are common used to treat mechanically pretreated municipal wastewaters in
many places in the world.
SSF which by definition must be planted with emergent macrophytes can best
be classified as horizontal flow or vertical flow (Figure 2.4). This classification is
based on the flow direction to the soil-and gravel layers. This technology is generally
limited to systems with low flow rates and can be used with less than secondary
pretreatment (Kadlec et al, 1978).
20
(a) Horizontal flow
(b) Vertical flow
Figure 2.4: General arrangement for the constructed wetland with
(a) a horizontal flow (Vymazal et al., 1998) and;
(b) a vertical flow (Cooper et al., 1996)
The disadvantages of SSF wetlands are that they are more expensive to
construct, on a unit basis than FWS wetlands. Because of the cost factor, SSF
21
wetlands are often used for small flows. SSF wetlands are maybe more difficult to
regulate than FWS wetlands, and maintenance and repair costs are generally higher
than for FWS wetlands. A number of systems have had problems with clogging and
unintended surface flows.
2.3.3
Wetland Vegetation
In the wetland ecosystem, wetland plants play crucial ecological roles and
predominantly contribute to water purifying property or water quality function.
According to (Kadlec and Knight, 1996) constructed wetlands are designed to use
water quality improvement processes occurring in natural wetlands, including high
primary productivity, low flow conditions, and oxygen transfer to anaerobic
sediments. Several of these processes are strongly linked to functional characteristics
of macrophytes. There are many types of wetland plants; some of them are emergent,
submerged and floating shown in Figure 2.5, 2.6 and 2.7, respectively.
As depicted in Figure 2.5, submerged plants are those that grow below the
water surface. These species are not effective for wastewater treatment due to the
requirement of light penetration into the water bodies. The second types of aquatic
plant, namely the floating type as shown in Figure 2.6, have their root portions
submerged but not attached to the soil. The submerged parts of the floating plant can
serve as a good habitat for the bacteria responsible for waste stabilization. According
to Polprasert (1989), many types of floating weeds are commonly used in polishing
wastewater but there are also some drawbacks in the operation and maintenance of
this kind of system because of the fast growth rate of floating plants and their
mobility.
The emergent plants tower their shoots distinctly above the water surface and
are attached to the soil by their roots such as cattail and bulrush as shown in Figure
2.7. These plants tend to have a higher potential in wastewater treatment, because
can they serve as a microbial habitat and filtering medium. Reed et al., (1988)
revealed the communities of the emergent plants have the capability of growing in a
22
wide range of substrates and variety of wastewaters. However, this research focused
on the capability of emergent plant Limnocharis flava.
(a)
(b)
Figure 2.5: Submerged aquatic plants; (a) hydrilla (Hydrilla verticillata);
(b) coontail (Ceratophyllum demursum) (Lim and Polprasert, 1998)
(a)
(b)
Figure 2.6: Floating aquatic plants; (a) water hyacinth (Eichhornia crassipes);
(b) water lettuce (Pistia stratiotes) (Lim and Polprasert, 1998)
23
(a)
(b)
(c)
Figure 2.7: Emergent aquatic plants; (a) bulrush (Scirpus longii); (b) cattail
(Typha latifolia); (c) reeds (Pragmites communis) (Lim and Polprasert, 1998)
2.3.4
Wetlands Function and Values
Wetland functions are often referred to the physical, chemical and biological
characteristics of wetlands. Similarly, the wetland values are referred to those
characteristics of wetlands that are beneficial to society. Wetland functions involve
the performance or execution of changes within the wetlands ecosystem. These
functions include biological, chemical and physical transformations in the diversity
forms and substances that exist within the wetland. Representative biological
functions include providing habitat for reproduction, feeding, and resting.
Representative physical functions include flood attenuation, groundwater recharge
and sediment entrapment. Representative chemical functions include nutrient
removal and toxics decontamination.
24
Wetland values on the other hand are sociological and subjective terms.
Values of wetlands are based on anthropogenic properties by which the wetlands are
determined to be useful, or impart beneficial to public. The value establishes a worth,
excellence, utility or importance of a given wetland function.
The study of wetland functional and values is the essential step in
understanding how wetlands perform as a wastewater treatment facility (USEPA
1983; Hammer 1989). Principal functions and values of wetlands are presented in
Table 2.5.
Table 2.5: Important Functions and Values of Natural Wetlands (Kent, 1994)
Functions
Flood water storage
Flooding reduction
Erosion control
Sediment stabilization
Sediment/toxicant retention
Groundwater recharge/discharge
Natural water purification
2.3.5
Values
Nutrient removal/retention
Chemical and nutrient sorption
Food chain support
Fish and wildlife habitat
Migratory waterfowl usage
Recreation
Uniqueness/Heritage values
Treatment Processes Mechanisms
Significantly, both natural and constructed wetland systems provide
wastewater treatment by reducing oxygen-demanding substances such as BOD and
ammonia, suspended solids, nutrients such as nitrogen and phosphorus, and other
pollutants such as metals. Primary, secondary, and incremental removal mechanisms
include physical, chemical and biological operations as well as plant uptake
(Sherwood et al. 1979, Reed et al, 1988 and Hammer, 1989).
(a)
Biochemical Oxygen Demand
25
Biological metabolism is the primary process for removal of BOD in a
wetland system. The diverse microbial populations in the water column consume the
soluble organic waste products. In the soil and sediment layer, the organics are
sorbed in the soil, and later, biologically oxidized into stable end products. Also,
sedimentation in FWS systems, and filtration in SSF systems are processes that
remove BOD associated with suspended organic materials. Typically, the wastewater
will receive some level of pre-application treatment which would have removed
essentially all BOD associated with suspended matter (Kent, 1994).
The principal biological activity in FWS wetlands is from algae and bacteria
where microbial growths are attached to structures such as plant stems and litter, in
the wetland. The phenomenon is akin to BOD removal in oxidation ponds and by
attached growth (trickling filter) treatment facilities. Loading rates are lower on SSF
wetland treatment systems due to the limited supply of oxygen which is
characteristic of these systems. While plant root systems are the key to treatment
performance, therefore making the selected plant species especially important.
(b)
Suspended Solids
Both FWS and SSF wetland systems effectively remove suspended solids
(SS). Settleable suspended solids are readily removed in the early stages of a FWS by
gravity settling in quiescent, shallow areas downstream of the system inlet. In the
case of wastewaters receiving little pretreatment, the distributed inflow design will
safeguard against development of adverse and detrimental conditions from sludge
buildups. In the SSF wetland, settleable solids are removed by filtration as the
wastewater moves through the underdrain system. For colloidal suspended solids, the
primary removal mechanism is bacterial metabolism in both types of wetland
treatment systems. Some filtering and sorption will occur in an SSF system (Kent,
1994).
In the FWS wetland suspended solids may be produced in the form of algae,
which also will produce diurnal swings in dissolved oxygen concentrations. In the
initial system cells, algae performs important treatment functions, as in an oxidation
pond, but the system design should limit the algae population in the later stages of
26
the wetland system so as to avoid permit violations. Nutrient reductions through the
system will help effect this requirement (Kent, 1994).
(c)
Nutrients
Constructed wetlands are an effective means to control the discharge of
nutrients such as nitrogen and phosphorus. The mechanisms for nutrient removal in a
wetland system are;
(i)
Direct plant uptake;
(ii)
Chemical precipitation;
(iii)
Uptake by algae and bacteria;
(iv)
Soil absorption;
(v)
Denitrification;
(vi)
Loss by insect and fish uptake.
The density and types of plants in the system will determine the direct and
indirect performance rates of these mechanisms. Thus, it is extremely important to
maintain a healthy plant community to ensure effective performance of the nutrient
removal mechanisms. Plant selection should be based on the species ability to
establish a stable community that will survive over the spectrum of the system’s
hydroperiod and other environmental conditions (Kent, 1994).
Both nitrogen and phosphorus must be considered simultaneously. The
wetlands community is composed of many different, interacting populations of
organisms functioning in a way unique to the site’s environmental conditions. Often,
either nitrogen or phosphorus is the limiting factor in an aquatic system, and the
addition of excess nutrients causes eutrophication or other undesirable changes in the
ecological community.
In a natural and constructed wetland system, the principal phosphorus
removal mechanisms are precipitation of phosphates under elevated pH conditions,
sorption within the bottom soils, uptake by the macrophytic plants and fixation by
algae and bacteria. Unlike denitrification for nitrogen removal, there is no single
27
long-term sink for phosphorus removal or retention. This deficiency requires that all
the phosphorus removal mechanisms be considered in the system design process.
In the wetland system, both organic and inorganic forms of phosphorus may
occur in a dissolved or particulate state in the water column and soil. The interchange
of phosphorus between the water and soil phases depends on several factors, such as
concentration gradients, pH, dissolved oxygen, and system hydraulics. The latter
includes velocity suspension of particulates and bottom scouring to re-suspend
settled particulates.
Soil and bottom sediments can be a significant phosphorus sink in mineral
soils. In this instance, dissolved inorganic phosphorus is removed through adsorption
to clays and precipitation as insoluble complexes of aluminum, calcium, and iron.
The aluminum and iron reactions prefer acid to neutral soils, whereas the calcium
reactions require alkaline conditions. Plants may then uptake the phosphorus,
especially which adsorbed to the soil.
To take advantage of mineral soils as a sink, the water in the system must be
moving in the soil column to afford reaction opportunities. The SSF wetlands reduce
the influence of water-soil interchanges of phosphorus and force movement through
the soil column. However, this approach limits the system’s hydraulic capacity
without a significant increase in wetland treatment area. If the area soils are mostly
organic, special provisions would be required to seek deeper, more mineral soils in
order to use the soil as a significant phosphorus removal mechanism (Kent, 1994).
Plant uptake influences the removal of nutrients and provides a significant
short-term phosphorus sink during establishment of the wetland system, but it is not
the principal phosphorus removal mechanism (Kent, 1994). Longer-term storage
occurs when the plants die and form a litter zone which forms peat (organic soils).
Likewise, fixation of phosphorus in algae and bacteria cells results in storage of
phosphorus in the bottom sediments. The stability of these phosphorus sinks depends
on several factors including the plant tissue decay rate, peat formation rate, and
occurrence of scouring.
28
(d)
Metals
The processes that affect the fate of metals are considered to be (Lim and
Polprasert, 1998): 1) adsorption or exchange of metals onto sediments in wetlands; 2)
formation of insoluble sulfides in reducing zones catalyzed by bacteria metabolism;
3) ion co-precipitation of iron and manganese hydroxide; 4) formation of insoluble
carbonates; 5) uptake by plants; and 6) physical filtration. The presence of clay soils
in an SSF enhances the opportunities of removal by adsorption. Filtration also will
remove suspended metals in an SSF wetland system. In a FWS system,
sedimentation will occur, and the development of neutral to alkaline conditions will
favor precipitation of metals. In both systems, metal uptake by plants may occur
(Kent, 1994). However, the effectiveness of water treatment has proved highly
variable at different sites (Fennesy, 1989). Although significant metals removals
have been observed for most of the wetland studied, the removal mechanisms are
poorly understood (Ying, 2003).
2.3.6
Treatment Performance
Although both SSF and FWS systems are known to be capable of effective
removal of many contaminants, a review of the literature indicates more research
efforts are being directed to SSF systems. The results of some studied of the
performance constructed wetlands for various wastewaters from international and
local researchers are summarized in Table 2.6. According to Lim and Polprasert
(1998), this is due to the following perceived merits of SSF systems:
(i)
Mosquito and odor problems do not arise since the water remains
subsurface; and
(ii)
Less surface area is required for SSF systems to achieve an equivalent
performance to that of FWS systems.
2.4
Magnet and Magnetism
29
Many people find magnets to be strange and complete mysterious things. A
magnet is an object that has a magnetic field. It can be in the form of a permanent
magnet or an electromagnet. Since 1831, electromagnetic induction was discovered
by Michael Faraday. He built two devices to produce what he called electromagnetic
rotation that is a continuous circular motion from the circular magnetic force around
a wire. His greatest discoveries were electromagnetic induction which means a
generation of electricity in a wire by means of the electromagnetic effect of a current
in another wire. The induction ring was the first electric transformer
The movement of a compass needle towards the North Pole and the attraction
of a fridge magnet to the refrigerator are two examples of magnetism in our everyday
lives. A magnet is an object that forms a magnetic field. As iron is a magnetic
material, iron filings shaken around a magnet will form along the lines of force and
produce the pattern of the magnetic field. Magnetic fields arise from charges,
similarly to electric fields, but are different in that the charges must be moving. For
example, electrons flowing in a wire will produce a magnetic field surrounding the
wire as shown in Figure 2.8. The force of charge felt when moving through a
magnetic field as depicted by the right-hand rule. The direction of the magnetic field
due to moving charges will also depend on the right hand rule. For a current-carrying
wire, the rule revealed that if the fingers of the right hand are placed around the wire
so that the thumb points in the direction of current flow (I), the fingers will be
pointing in the direction of the magnetic field produced by the wire.
Current, I
Magnetic Field, B
Figure 2.8: Right-hand rule (Bruk et al, 1987)
30
Table 2.6: Comparison of different performance constructed wetlands.
Reference
System
type
SSF cattail
SSF reed
SSF bulrush
SSF gravel
Wastewater
type
Primary
municipal
wastewater
Roser et al.
(1987)
SSF cattail
SSF bulrush
SSF gravel
Moore et al.
(1994)
Wildeman and
Laudon (1989)
Gersberg et al.
(1986)
Removal efficiency (%)
TP
TN
28*
78*
94*
11*
BOD
74
81
96
69
COD
-
SS
91
86
94
90
Fe
-
Mn
-
Secondary
clarified sewage
effluent
88
86
88
-
93
89
93
23
19
24
48
54
50
-
-
FWS cattail
FWS bulrush
FWS stones
Pulp mill waste
18
27
33
-
53
42
76
-
-
-
-
SSF mushroom
compost
SSF peat + aged
manure +
decomposed
wood products
SSF 10-15cm
limestone rock
and peat + aged
manure +
decomposed
wood products
Acid mine
drainage
-
-
-
-
-
38
10
-
-
-
-
-
35
2
-
-
-
-
-
30
0
Notes: BOD=Biochemical Oxygen Demand; COD=Chemical Oxygen Demand; SS=Suspended Solids; TP=Total phosphorus; TN=Total nitrogen; Fe=Ferum; Mn=Manganese
* = ammoniacal-N
31
Table 2.6: Comparison of different performance constructed wetlands. (cont’)
Reference
System
type
SSF bulrush
SSF gravel
HRT= 2 days
Wastewater
type
Dairy farm
wastewater
BOD
76
60
COD
-
SS
78
73
Crolla and
Kensley
(2002)
SSF cattail
Dairy milkhouse
-
-
-
58
Hammer et al.
(1993)
SSF cattail
SSF reed
Swine
-
-
-
Hunt and Poach
(2000)
SSF bulrush
SSF cattail
Swine
-
-
Kuusemets et
al.
(2002)
SSF bulrush
Domestic
wastewater
Harish.
(2001)
SSF cattail
SSF mangrove
fern
SSF seaoxeye
SSF sedge
Shrimp
aquaculture
wastewater
Tanner et al.
(1995a)
-
-
Removal efficiency (%)
TP
TN
-
Fe
-
Mn
-
72
-
-
75
90
-
-
-
35
81 to 94
-
-
59
5
(due to
plant
uptake)
48
8
(due to
plant
uptake)
-
-
-
Notes: BOD=Biochemical Oxygen Demand; COD=Chemical Oxygen Demand; SS=Suspended Solids; TP=Total phosphorus; TN=Total nitrogen; Fe=Ferum; Mn=Manganese
•
= ammoniacal-N
32
Table 2.6: Comparison of different performance constructed wetlands. (cont’)
Reference
System
type
SSF bulrush
SSF cattail
SSF reed
Wastewater
type
Cereal and dairy
wastewater
Ydstebo et al.
(2000)
SSF cattail
Greenway and
Woolley
(2000)
Removal efficiency (%)
TP
TN
20-44
-
BOD
-
COD
-
SS
-
Agricultural
runoff
-
-
-
70-85
SSF cattail
Municipal
wastewater
-
-
-
Kim and Geary
(2000)
SSF bulrush
Simulated high P
loading
-
-
-
Navanitha
(2005)
SSF cattail
SSF gravel
Landfill leachate
66
56
Aeslina
(2004)
SSF cattail with
Safety Flow
Landfill leachate
70
Noor Ida
Amalina (2005)
FWS water
hyacinth
enhanced with
magnetic field
Landfill laechate
83
Braskerud
(2000)
Fe
-
Mn
-
-
-
-
21 to 28
81 to 87
-
-
-
-
-
-
5
(due to
plant
uptake)
57
90*
-
-
80
-
80
90*
-
-
78
-
60
96*
69
60
Notes: BOD=Biochemical Oxygen Demand; COD=Chemical Oxygen Demand; SS=Suspended Solids; TP=Total phosphorus; TN=Total nitrogen; Fe=Ferum; Mn=Manganese
•
= ammoniacal-N
The strength of a magnet is given by its magnetic flux density, which is
measured in units of gauss. The earth's magnetic field is on the order of 0.5 gauss
(Marshall and Skitek, 1987). Typical household refrigerator magnets have field
strengths of about 1,000 gauss. The SI unit of magnetic field strength is the tesla, and
the SI unit of total magnetic flux is the weber. 1 weber = 1 tesla flowing through 1
square meter, and is a very large amount of magnetic flux. A smaller magnetic field
unit is the Gauss (1 Tesla = 1,000 Gauss).
2.4.1
Effect of Magnetic Field to Molecules
Basically, magnets have locations on them, called poles. Pole comes in two
types, which are called North poles and South poles. Opposite pole types attract as
depicted in Figure 2.9, while poles of the same type repel each other. A magnetic
field can be produced by aligning the positives and the negatives to opposite ends of
any magnetic material. Poles of either type attract iron, steel, and a few other metals
such as nickel.
Figure 2.9: Magnetic field directed out from north pole (N) to
south pole (S) (Bruk et al., 1987)
34
A force on moving charges particle of magnetic field is called Lorentz force.
As illustrated in Figure 2.10, the interaction between magnetic and electric fields will
result a force generated in a direction perpendicular to the plane formed by the
magnetic and electric field vectors. The moving charges or ions resulting weak
electrical current giving additional force to the charged particle so called Lorentz
force. The velocity of particle will increased as the changes of direction flow will
occurred depending on strength of magnetic field and charge density (Spiegel, 1998).
The molecules of a substance may be classified as either polar or nonpolar. A
nonpolar molecule is one in which the center of gravity of the positive nuclei and the
electrons coincide, while a polar molecule is one in which they do not. Symmetrical
molecules like H2, N2, and O are nonpolar while molecules like H2O and N2O are
polar.
Lorentz ForceForce in positive charge
90°
90°
90°
Electric
Magnetic
Field
(South Pole)
Figure 2.10: Positioning of fields and force (Bruk et al, 1987)
Under the influence of a magnetic field, the charges of a nonpolar molecule
become displaced (Figure 2.11). These molecules are said to become polarized by
the magnetic field and are called induce dipoles. The restoring force pulls the
molecules together. The charges separate until the restoring force is equal and
opposite to the force exerted on the charges by the field. Polar molecules are oriented
35
at random when no magnetic field is provided. When under the influence of a
magnetic field the dipoles point toward the direction of the field (Figure 2.12).
Arrangement of nonpolar
molecules in the absence of a
magnetic field.
Arrangement of nonpolar
molecules under the influence of
a magnetic field.
Figure 2.11: Nonpolar displacement (Vickl, 1991)
Arrangement of polar molecules
in the absence of a magnetic field.
Under the influence of a
magnetic field
Figure 2.12: Polar displacement (Vickl, 1991)
2.4.2
Magnetic Mechanism
Colloidal particles dispersed in a solution are electrically charged due to their
ionic characteristics and dipolar attributes. Negative charged ions in each particle
36
make them repel each other. Each particle dispersed in a solution is surrounded by
oppositely charged ions. Collision with high velocity and reduction of repelling time
will occur when the solution is applied to the magnetic field. Thus, the colloidal
particles will form larger molecules to induce coagulation system. This reaction is
shown by Figure 2.13.
Magnet
Magnetic Field
Flow
Magnet
Colloidal particle far each
other
Magnetic
Mechanism
Colloidal particle coagulate to
form larger molecules
Figure 2.13: Reaction of charged ion in solution when exposed to magnetic field
(Klassen, 1981)
Before the concept of colloidal system were revealed, the colloidal particle is
hard to be eliminated because of same charged ions. To undergo this situation, the
charges have to be neutralized through sedimentation and flocculation. Since
findings from Vermeiran (1958); Klassen (1981) revealed the magnet potential, their
proven are magnetic water treatment increased the efficiency of coagulation and
flocculation total suspended solids in water. Others, magnetic treatment also increase
coagulation processes in iron (Duffy, 1977; Tombaez et al, 1991).
Magnetic treatment devices are available in various configurations, which are
electromagnets and single or arrays of permanent magnets with many different
orientations of magnetic field. These devices can be placed in side or outside of the
pipe. Gruber and Carda (1981) had proposed various orientation of permanent
magnet as depicted in Figure 2.14, each employing different orientations of magnetic
37
field. Some units employ a field that is orientated approximately orthogonal to the
direction of flow (class II and class III) whilst others employ a mostly parallel field
(class I and IV). Where a study has used a particular device, this will be identified if
possible to enable the reader to make comparisons about the effectiveness of each
type.
Class I
Class II
Class III
Class IV
Figure 2.14: Classification of permanent magnet type (Baker and Judd, 1996)
Magnetic treatment devices can be arranged in two installation variations and
three operational variations. First to be discussed are the two installation variations:
invasive and noninvasive. Invasive devices are those which have part or all of the
operating equipment within the flow field. Therefore, these devices require the
removal of a section of the pipe for insertion of the device. This will necessitates an
amount of time for the pipe to be out of service. Non-invasive devices are completely
external to the pipe, and thus can be installed while the pipe is in operation. Figure
2.15 illustrates the two installation variations.
38
Magnet
Flow
Flow
Invasive Device
Non-Invasive Device
Figure 2.15: Illustration of classes of magnetic devices by installation location
(AWWA, 1998)
The operational variations have been mentioned above; illustrations of the
latter two types are shown Figure 2.16:
(i)
Magnetic, more correctly a permanent magnet
(ii)
Electromagnetic, where the magnetic field is generated via
electromagnets
(iii)
Electrostatic, where an electric field is imposed on the water flow,
which serves to attract or repel the ions and, in addition, generates a
magnetic field
-
+
Flow
Electromagnetic Device
Figure 2.16: Illustration of classes of non-permanent magnet devices
(AWWA, 1998)
39
2.4.3
Magnetic Treatment
One of the primary needs of mankind over the next millennium is improved
and less expensive water or wastewater treatment methods. Works by Faraday and
Maxwell have revealed the effect of electromagnetic fields on the behavior and the
properties of matter. Nowadays, more relevant articles and reports are available, so
clearly magnetic water treatment has received some attention from the scientific
community. The reported effects of magnetic water and wastewater treatment,
however, are varied and often contradictory. In many cases, researchers report
finding no significant magnetic treatment effect. In other cases, however, reasonable
evidence for an effect is provided. Table 2.7 shows the summary of water and
wastewater treatment enhanced with magnetic field, respectively.
Table 2.7: Summary of magnetic treatment
No.
1.
References
Liburkin et
al.
(1986)
Types of
Influent
Ordinary
water
Findings
•
Magnetic treatment affected the structure of
gypsum (calcium sulfate).
•
Gypsum particles formed in magnetically treated
water were found to be larger and "more regularly
oriented" than those formed in ordinary water.
Magnetic treatment changed the mode of calcium
carbonate precipitation such that circular discshaped particles are formed rather than the
dendritic (branching or tree-like) particles
observed in nontreated water.
2.
Kronenberg
(1985)
Non-treated
water
•
3.
Chechel and
Annenkove
(1972)
Martynova et
al.
(1967)
Ordinary
water
• Magnetic
4.
Joshi and
Kamat
(1996)
Bruns et al.
(1966)
Klassen
(1981)
Ordinary
water
•
Magnetic treatment affects the nature of hydrogen
bonds between water molecules.
•
They report changes in water properties such as
light absorbance, surface tension, and pH.
treatment affects the structure of
subsequently precipitated solids.
• Scale
formation involves precipitation and
crystallization.
• These studies imply that magnetic water treatment
is likely to have an effect on the formation of scale.
40
5.
Lipus et al.
(1994)
Types of
Influent
Ordinary
water
6.
Duffy
(1977)
Ordinary
water
No.
7.
8.
9.
10.
References
Busch et al.
(1986)
Donaldson
(1988)
Lipus et al.
(1994)
Krylov et al.
(1985)
Gehr et al.
(1955)
Parsons et al.
(1997)
Higashitani
and Oshitani
(1997)
Ordinary
water
Calsium
carbonate
fluid
Calcium
sulfate fluid
Calcium
sulfate fluid
Findings
•
The characteristic relaxation time of hydrogen
bonds between water molecules is estimated to be
much too fast and the applied magnetic field
strengths much too small for any such lasting
effects.
•
Provides experimental evidence that scale
suppression in magnetic water treatment devices is
due not to magnetic effects on the fluid, but to the
dissolution of small amounts of iron from the
magnet or surrounding pipe into the fluid.
•
Iron ions can suppress the rate of scale formation
and encourage the growth of a softer scale deposit.
•
Measured the voltages produced by fluids flowing
through a commercial magnetic treatment device.
•
Their data support the hypothesis that a chemical
reaction driven by the induced electrical currents
may be responsible for generating the iron ions
shown by Duffy to affect scale formation.
•
Emerging the effect results from the interaction of
the applied magnetic field with surface charges of
suspended particles.
•
Found that the electrical charges on calcium
carbonate particles are significantly affected by the
application of a magnetic field.
•
Further, the magnitude of the change in particle
charge increased as the strength of the applied
magnetic field increased.
•
Found that magnetic treatment affects the quantity
of suspended and dissolved calcium sulfate.
•
A very strong magnetic field (47,500 gauss)
generated by a nuclear magnetic resonance
spectrometer was used to test identical calcium
sulfate suspensions with very high hardness (1,700
ppm on a CaCO3 basis).
•
Two minutes of magnetic treatment decreased the
dissolved calcium concentration by about 10%.
•
The magnetic field decreased the average particle
charge by about 23%.
• These results, along with Gehr et al, imply that
application of a magnetic field can affect the
dissolution and crystallization of at least some
compounds.
41
No.
References
11.
Petruska and
Perumpral
(1978)
Types of
Influent
Food
processing
wastewater
12.
Coey and
Cass (2000)
13.
Johan Sohaili
(2003)
14.
Wan Salida
(2006)
Findings
•
High gradient magnetic separation (HGMS) for
treating food processing wastewater can cause
reductions in TP, SS and chemical oxygen
demand.
Calcium
carbonat fluid
•
Their study on precipitation of CaCO3, indicate
that magnetic effect is maintained for at least 60
hours after exposure to the magnetic field.
Domestic
wastewater
•
Revealed the capability of magnetic field is
potentially an alternative method in increasing
formation and sedimentation rate of suspended
particles in wastewater treatment.
•
This capability will help to decrease the retention
time, size of sedimentation basin and increase the
treatment efficiency.
•
Most of suspended solids are organic matter that
contributes to concentration of contamination such
as BOD5, COD, SS and nitrate in wastewater.
•
Leachate that is treated with magnetic field would
result in decrease of heavy metal and nutrient
concentration.
•
Magnetic field enhances the heavy metal removal
in the leachate in settling column by accelerating
the settlement time for the magnetized leachate.
Landfill
leachate
The summary table indicates the acceptance of magnetic treatment as an
alternative form of wastewater treatment remains limited because of the lack of a
credible mechanism (Baker and Judd, 1996). Magnetism technology is one of the
technologies which are favour of cost and easy maintenance. Besides, it does not
affect peripheral consequence towards water quality that had being treated
(Florestano et al, 1996).
2.5
Conclusion
Concept of using constructed wetlands to treat wastewater is relatively new in
Malaysia. However the results achieved so far from international researchers have
42
encouraged great expectations about the technology and what can be achieved
further. The wetlands can be used in a sustainable manner, by defining a clear design
objective for the wetland system to achieve its ultimate goal and close monitoring to
assess the performance of the wetlands to ensure all objectives are fulfilled. Wetlands
can be considered a pioneer venture in constructed wetland treatment system in
Malaysia.
It is a good example of a wetland to be adapted to treat a variety of
wastewaters including landfill leachate. The implementation of constructed wetland
in treating leachate can be a low-energy process requiring minimal operational
attention. Treatment processes of constructed wetlands are highly effective to treat
pollutants from unknown sources and can be accomplished with the least cost
compared to other treatment methods (Lim et al.2003).
Magnetic treatment is relatively synonym with treated and untreated ordinary
water. There were less reported for wastewater including leachate. It is therefore
important to ascertain the magnetic treatment of landfill leachate. Due to excellent
removal of particle (TSS) and heavy metal, magnetic field treatment can be adapted
in treating leachate. Leachate was containing high concentration of heavy metal.
With ability to separate positive and negative charge in particle, magnet can form
larger floc or colloid and can enhance precipitation process. The flocculation can
increased when applying high magnetic strength with low flowrate.
As the conclusion, the concept of treating leachate with constructed wetland
enhanced with magnetic field can contribute to higher nutrient and heavy metal
removal, hence, also can reduce the time efficiency to reduce or remove the
pollutants.
43
CHAPTER 3
METHODOLOGY
3.1
Introduction
This chapter will discuss the methodology applied in order to carry out the
tests and analysis on the treatment of leachate using subsurface flow constructed
wetland (SSF) enhanced with magnetic field.
There were two systems of subsurface flow constructed wetlands (SSF) and
each system was carried out for a period of 18 days. The first system was conducted
as vertical flow (VF) while second system was horizontal flow (HF). Each system
contained 3 tanks, each performing as a constructed wetland. Tank A was not planted
for control purposes whilst tank B and C was planted with 8 clusters of Limnocharis
flava. In addition, a sample discharged from tank C was treated with magnetic field
for 6 hours;
The performance of the constructed wetland enhanced with magnetic field
can be evaluated from the quality of the wetlands effluent. The flow of the overall
experiments for each system is shown in Figure 3.1.
44
Experimental Set up
-Set up experimental scale
constructed wetland systems
Leachate Sample
Vertical Flow System (18 days):
(i)
Reactor A (Control)
(ii)
Reactor B (Vegetated)
(iii)
Reactor C (Vegetated with
Horizontal Flow System (18 days):
(i)
Reactor A (Control)
(ii)
Reactor B (Vegetated)
(iii)
Reactor C (Vegetated with
magnetic field)
magnetic field)
Effluent Collection
Laboratory effluent analysis
• Total suspended solid
• Turbidity
• Ammoniacal nitrogen
• Nitrate
• Phosphorus
• Ferum
• Manganese
Figure 3.1: Flow chart of the experiments
45
3.2
Leachate Collection
Leachate needs to be collected before any experiment can be done. The field
techniques used for this study was sample collection. For this study, raw leachate
samples were collected from Tanjung Langsat landfill, Johor. Prior to the leachate
collection, permission has required from the authorities. The samples were collected
in plastic container. Upon collection, the leachate was stored at 4°C to minimize any
further change that might occur in its physiochemical and biological properties until
the experiments analyses were carried out within a week.
3.3
Experimental Setup
The experiments were carried out in a lab-scaled horizontal subsurface flow
constructed wetland (SSF) which consists of (Figure 3.2):
(i)
Three tanks with dimensions 38 cm length x 28cm width x 30 cm
depth each for constructed wetland.
(ii)
Three storage tanks 30cm length x 30 cm width x 30 cm depth each.
(iii)
Three collection tanks and
(iv)
Magnetic field 0.55 Tesla magnet strength.
Leachate from storage tank was entering each tanks of constructed wetland at
equal time. However, leachate effluent from tank C was treated with magnetic field
for 6 hours at interval of 3 days. For each system, all the plants and media were
removed and replaced with new plants and media. Leachate effluents were
continuously daily return feed from the collection tanks. All systems are operated
under gravity flow. Each reactor contained the same quantity of leachate and the
experiments were conducted under natural environmental conditions which will be
exposed to sunlight and open space. Plant leaves and roots were harvested for each
constructed wetland and were analyzed after being treated by each system.
46
Collection Tank
Storage Tank
REACTOR A
Control
(a)
Collection Tank
Storage Tank
REACTOR B
Vegetated
(b)
Magnetic field
CollectionTank
Storage Tank
REACTOR C
Vegetated with Magnetic
Field Treatment
(c)
Figure 3.2: Schematic plan of the SFS system used in the experiments;
(a) Control; (b) Vegetated and; (c) Vegetated with magnet treatment systems
Samplers of leachate before being treated using constructed wetland were
taken for each reactor. Then, after being treated samplers were taken at collection
tank (Figure 3.2). Sampling works were done at intervals of 3 days.
47
Figure 3.3: Subsurface flow constructed wetlands for overall experiments
(a)
(b)
(c)
Figure 3.4: Tank (a) Control; (b) Vegetated; and (c) Vegetated with magnet
48
3.3.1
Magnetic Devices
The magnetic devices used in the experiments as depicted in Figure 3.5 was
schematically illustrated in Figure 3.6 and Figure 3.7. It consisted of a series of pairs
of permanent magnets 0.55 Tesla with north and south poles facing each other, which
can be associated alternately. The leachate to be treated passed through a pipe
inserted between the polar pieces in opposition of polarity. In this configuration the
magnetic induction was perpendicular to the solution flow. Each polar piece is the
assembling of two rectangular permanent magnets (42x25mm2 and 6mm thick). The
magnetic circuit of each pair of magnets was partially closed by U-shaped pieces of
mild steel, to close the magnetic field in the gap. The various pairs were separated by
12 mm.
Figure 3.5: Magnetic devices used in the experiment
49
Magnet
PVC pipe
Figure 3.6: Schematic magnetic devices used in the experiments
Wood block
Magnet
Plastic joint
PVC pipe
Figure 3.7: Cross section of magnetic devices used in the experiments
3.3.2
Media
In this study, the media used consists of a 10 cm layer of coarse stone with
15-20mm diameter, followed by a layer of sand with 5-10mm diameter and a layer of
soil at the surface.
50
3.3.3
Plant
For the purpose of this leachate treatment, a species of wetland plant called
Limnocharis flava (yellow burhead) has been chosen for various reasons. Firstly, it is
one of the most common wetland plants available in this region as it is also one of
the wetland plants in Putrajaya wetland (Lim et al, 1998). The description of the
plant chosen for this study is shown in Table 3.1 and Figure 3.6.
Table 3.1: Description of the plant
Item
Description
Scientific Name :
Family :
Local names :
Origin:
Brief Description:
Limnocharis flava Buch
Limnocharitaceae (Butomaceae)
Yellow bur head, yellow sawah lettuce, yellow velvetleaf.
Tropical America
Perennial, erect, robust marsh herb, rooting in mud and strongly
tillering, 20-100 cm tall. Leaves basal, tufted, glabrous, broadly
oval-oblong in outline, with long angular leafstalk, 30-75 cm long.
Inflorescence stalk as long as the leaves, axillary, glabrous, with 515 flowers. Flowers fairly large, in the axils of membranous bract on
3-7 cm pedicel, pale yellow. Fruit compound, consisting of many
follicles, 1.5-2 cm, with numerous seeds. Young inflorescence and
flower buds consumed as a vegetable.
Common in ditches and shallow rivers. It has the potential of taking
over from targetted species, especially in shallow marsh. The fruit
capsules split into many follicles and float the water, rendering it
rather unsightly.
Potential Threat:
Figure 3.8: Limnochlaris flava (yellow burhead)
51
3.4
Analysis Procedure
All the tests were carried out in Environmental laboratory, Faculty of Civil
Engineering. The tests include parameter such as turbidity, suspended solid, tests for
nutrients such as nitrate and phosphate and test for heavy metal such as ferum and
manganese. The entire tests are carried out using DR-4000 HACH
spectrophotometer.
Table 3.2: Method Applied for Parameter Analysis
Parameter
Method Used
Method Code
TSS
Turbidity
Attenuated Radiation
10047
Ammonia nitrogen
Nessler
8038
Nitrate nitrogen
Cadmium Reduction
8039
Phosphate
Molybdovonate
8114
Ferum
Ferrover
8008
Manganese
PAN
8149
Source
*SA
DR/4000
DR/4000
DR/4000
DR/4000
DR/4000
DR/4000
*Standard method
3.5
Analysis of heavy metals in plant tissues
The heavy metal uptake by plants was studied. After 18 days of experiment,
the plant’s leaves and roots were harvested for each constructed wetland. First, the
leaves and roots were washed with tap water and distilled water. After that, the plant
samples were dried in an oven at 1050C and ground with mortar and pestle. 0.9 – 3.0
g of the ground plant sample was put inside the conical flask 250 ml and 50 ml of 2
M hydrochloric acid was added in for plant digestion. The sample mixture was
centrifuged for 20 minutes and filtered with cellulose acetate membrane 0.45 μm.
The filtrate was then analyzed for heavy metal (Fe and Mn).
CHAPTER 4
RESULTS AND DISCUSSION
4.1
Introduction
The results obtained from the experimental analysis of SSF constructed
wetlands enhanced with magnetic field will be discussed in details in this chapter.
Resultant, all data will be carried out in graphical approach to evaluate the specific
analysis processes. Analysis of variance (ANOVA) has been used to reveal
significant differences for all treatments. Statistical significance differences were
tested at p≤0.05 (95% levels of significance). Thus, an extensive discussion had been
concluded in the behavior obtained comparing significant differences between the
three tanks (control, vegetated and vegetated with magnet treatment systems) and
comparing significant differences between vertical and horizontal SSF systems.
The experimental studies were carried out for about two months from July
until September. The effluent was tested for the removal of suspended solid (TSS),
turbidity, nitrate (NO3-N), phosphorus (P), ammoniacal nitrogen (NH4-N), ferum (Fe)
and manganese (Mn). The removal efficiency from tank A, indicated as control, B
indicated as vegetated and C indicated as vegetated with magnet were compared to
evaluate the trends for the overall performance.
53
The quality of the raw leachate after being 50% diluted and the effluent
quality after the leachate was treated using the SSF constructed wetlands are
summarized in Table 4.1.
Table 4.1: Comparison between initial and effluent quality of leachate
Leachate concentration(mg/L)a
After 18 days of treatment
Tank A
Tank B
Tank C
Parameters
Initial
Control
Planted
Planted with magnet
VF
HF
VF
HF
VF
HF
TSS
73.6 41.30 39.50 38.50 38.00
10.01
7.33
Turbidity
120
42.00 46.00 28.00 21.00
10.00
8.00
26.5
9.00 8.90 8.00 4.80
8.00
3.20
NO3-N
P
52.8
26.3 25.2 23.50 20.10
6.00
4.80
NH4-N
136
18.02 28.05 8.01 26.70
8.28
32.20
Fe
0.81
0.08 0.06 0.03 0.03
0.00
0.00
Mn
0.4
0.02 0.03 0.01 0.00
0.01
0.00
a
Except for turbidity = NTU
V= Vertical system; H= Horizontal system.
4.2
Treatment Process Mechanisms
Pollutant maybe removed as a result of more than one type of mechanisms at
work. The principal pollutant removal mechanisms operative in wetland systems are
listed in Table 4.2. Furthermore in this chapter, the performance data of constructed
wetland in the removal of all parameters will be discussed in detail.
4.3
Total Suspended Solid Removal
Total suspended solid (TSS) removal is best facilitated through the
encouragement of settling in constructed wetlands. Figure 4.1 shows the overall
performance of TSS removal for vertical and horizontal subsurface flow (SSF)
constructed wetland systems.
54
Table 4.2: Summary of removal mechanisms in wetlands for the pollutants in
wastewater (Stowell et al., 1981)
Filtration
Adsorption
BOD
N
P
Heavy metals
Refractory organics
Bacteris & virus
Physical
sedimentation
Colloidal solids
Mechanism
Settleable solids
Pollutant affecteda
P
S
I
I
I
I
I
I
S
S
Interparticle attractive forces (van der
Walls force).
S
Volatilization of NH3 from the
wastewater
S
Chemical
precipitation
P
P
Adsorption
P
P
Decomposition
P
P
Plant
metabolism
Plant
absorption
Natural die-off
a
b
Formation of or co-precipitation with
insoluble compound.
S
S
S
On substrate and plant surfaces.
S
P
P
Gravitational settling of solids in
wetland settings.
Particulates filtered mechanically as
water passes through substrate, and
root masses.
Volatillization
Biological
bacterial
metabolismb
Description
P
Decomposition or alteration of less
stable compounds by phenomena such
as UV irradiation, oxidation and
reduction.
P
Removal of colloidal solids and
soluble organics by suspended,
benthic and plant supported bacteria.
S
Uptake and metabolism of organics
by plant. Root excretion maybe toxic
to organisms of enteric origin.
S
Under proper condition, significant
quantities of pollutants will be taken
up by plant
S
P
Natural decay of organisms in an
unfavorable environment
P= primary effects; S= secondary effect; I= incidental effect (effect occurring incidental to removal of another pollutant).
The term metabolism includes both biosynthesis and catabolic reactions.
55
On comparing the performance of the two types of wetland systems, greater
level of TSS removal was observed in control, vegetated and vegetated with magnet
for the horizontal SSF. For vertical system, the TSS removal efficiency is 44% for
control, 48% for vegetated and 86% for vegetated with magnet treatment. While for
horizontal system, the SS removal efficiency is 46% for control, 48% for vegetated
and 90% for vegetated with magnet treatment, respectively
100
90.04
86.40
90
80
TSS removal (%)
70
60
50
43.89
46.33
47.69
48.37
Vertical SSF
Horizontal SSF
40
30
20
10
0
Control
Vegetated
Vegetated with magnet
Types of treatment systems
Figure 4.1: Suspended solids removal for vertical and horizontal SSF system
From the results, control and vegetated treatment for both systems were
observed lower removal efficiency as compared to vegetated with magnet treatment.
This indicated TSS removal due entirely to sedimentation and filtration rather than
biological process associated with the plants or microbial community (Gersberg et
al., 1986) since the removal efficiencies for the vegetated tanks were not
significantly different from the control tank. Most of the suspended solids are
filtered out and settled beyond the substrate of constructed wetlands. The
accumulation of trapped solids is a major threat for good performance of horizontal
systems as the solids may clog at the bed (Vymazal, 2005a). Therefore, the effective
pretreatment is necessary for horizontal SSF systems.
56
1.2
Concentration (C/Co)
1.0
0.8
Control
0.6
Vegetated
Vegetated
with magnet
0.4
0.2
0.0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(a) Vertical SSF
1.2
Concentration (C/Co)
1.0
0.8
Control
0.6
Vegetated
0.4
Vegetated
with magnet
0.2
0.0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(b) Horizontal SSF
Figure 4.2: Comparison of TSS concentration (C/Co) for; (a) Vertical and;
(b) Horizontal SSF system with and without magnetic field
Figure 4.2 depicted the concentration of TSS for all treatment systems. The
figures shows obviously decreased in TSS for vegetated with magnet treatment. A
charged ion in colloidal particles was neutralized through sedimentation and
flocculation and when exposed to magnetic field, the efficiency of coagulation and
57
flocculation suspended solids were increased in vegetated with magnet treatment
system which obtained the highest SS removal. This trend of using magnetic
treatment was similar to what were observed by Vermeiran (1958); Klassen (1981);
Johan (2003).
4.4
Turbidity Removal
Figure 4.3 shows the overall performance of turbidity removal for vertical
and horizontal subsurface flow (SSF) constructed wetland systems.
100
89.17
Turbidity removal (%)
90
86.67
80
70
64.17
60.00
65.00
Vertical SSF
61.67
Horizontal SSF
60
50
40
Control
Vegetated
Vegetated with magnet
Types of treatment systems
Figure 4.3: Turbidity removal for vertical and horizontal SSF system
As TSS, similar trend was observed in turbidity removal. On comparing the
performance of the two types of wetland systems, greater level of turbidity removal
was observed in horizontal SSF for control, vegetated and vegetated with magnet
treatment. For vertical system, the turbidity removal efficiency is 60% for control,
64% for vegetated and 87% for vegetated with magnet treatment. While for
58
horizontal system, the turbidity removal efficiency is 62% for control, 65% for
vegetated and 90% for vegetated with magnet treatment, respectively.
0.9
0.8
Concentration (C/Co)
0.7
0.6
Control
0.5
Vegetated
0.4
Vegetated
with magnet
0.3
0.2
0.1
0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(a) Vertical SSF
0.8
0.7
Concentration (C/Co)
0.6
0.5
Control
0.4
Vegetated
0.3
Vegetated
with magnet
0.2
0.1
0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(b) Horizontal SSF
Figure 4.4: Comparison of turbidity concentration (C/Co) for; (a) Vertical and;
(b) Horizontal SSF system with and without magnetic field
59
Reduction of turbidity as depicted in Figure 4.4 due to sedimentation and
filtration as well as removal of TSS. Typically, a biological process associated with
the plants was not contributed to turbidity removal since the percentage between
control and vegetated treatment was not significantly different. The effect of
magnetic field to colloidal particles as mention primarily was contributed to
decreasing of turbidity concentration than other treatments. Thus, magnetic field
provided better reduction in TSS and turbidity monitored.
4.5
Nutrients Removal
Three types of nutrients were studied which were ammoniacal nitrogen
(NH4-N), nitrate (NO3-N) and phosphorus (P).
4.5.1
Ammoniacal Nitrogen
Figure 4.5 shows the overall performance of NH4-N removal and Figure 4.6
shows the concentration for vertical and horizontal subsurface flow (SSF)
constructed wetlands. In this study, the high NH4-N content was mainly due to the
fact that after NH4-N was formed by ammonification, it was unsuccessfully degraded
under anaerobic landfill conditions (Christensen et al., 1997). On comparing the
performance of the two types of wetland systems, greater level of NH4-N removal
was observed in control, vegetated and vegetated with magnet for the vertical SSF.
Horizontal flow cannot provide nitrification because of their limited oxygen
transfer capacity (Vymazal, 2005a). Tanner (1994) pointed out that in terms of land
area, the vertical flow wetlands received 2.5 times greater area oxygen dissolved
(DO) within the influent wastewater than the horizontal flow. Apart of that, the main
sources of oxygen in SSF wetlands are diffusion from the atmosphere through the
water surface and via plant shoots into the root zone.
60
100
94.11
NH4-N removal (%)
95
93.91
90
86.75
Vertical SSF
85
Horizontal SSF
80.37
80
79.38
76.32
75
70
Control
Vegetated
Vegetated with magnet
Types of treatment systems
Figure 4.5: Ammoniacal nitrogen removal for vertical and horizontal SSF
system
The major removal mechanism of NH4-N is nitrification/denitrification
(Galbrand, 2003; Vymazal, 2005b). Field measurements have shown that the
oxygenation of the rhizosphere of horizontal flow constructed wetlands is
insufficient and, therefore, incomplete nitrification is then major cause of limited
NH4-N removal (Vymazal, 2005a). Zhu et al., (1994) pointed out that no obvious
nitrification could be observed when DO concentration is lower than 0.5 mg/L.
In general, nitrification which is performed by strictly aerobic bacteria, which
is called Nitrosomonas bacteria is mostly restricted to areas adjacent to roots and
rhizomes where oxygen leaks to the filtration media. The NH4-N will be oxidized by
Nitrosomonas to nitrite (NO2-) which is then oxidized to nitrate (NO3-) by
Nitrobacter bacteria (Galbrand, 2003). Reduction of NH4-N concentrations as
depicted in Figure 4.6 indicated that microorganisms in the humic had transformed
the NH4-N to nitrate through nitrification. Nitrate, which is extremely mobile, is
usually quickly assimilated by plants or microorganisms, reduced by anaerobic
bacteria to nitrogen gas via denitrification or reduced back by ammonium by both
aerobic and anaerobic bacteria (Mitsch and Gosselink, 2000).
61
1.0
0.9
Concentration (C/Co)
0.8
0.7
0.6
Control
0.5
Vegetated
0.4
Vegetated
with magnet
0.3
0.2
0.1
0.0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(a) Vertical SSF
1.0
0.9
Concentration (C/Co)
0.8
0.7
0.6
Control
0.5
Vegetated
0.4
Vegetated
with magnet
0.3
0.2
0.1
0.0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(b) Horizontal SSF
Figure 4.6: Comparison of NH4-N concentration (C/Co) for; (a) Vertical and;
(b) Horizontal SSF system with and without magnetic field
The highest NH4-N removal was observed in vegetated vertical SSF system
which was 94.11%. Compared to control vertical SSF, the removal was 86.75%, thus
indicated that the presence of vegetations (Limnocharis flava) had improved the
treatment efficiencies of NH4-N. Vegetation plays a significant role by assimilating
62
NH4-N into plant tissue and providing an environment for nitrification-denitrification
in the root zone known as rhizosphere (Brix, 1994; Hammer, 1993; Maehlum, 1999).
However, magnetic field does not significantly contribute in NH4-N removal
in the wetland since the removal efficiency was similar to vegetated vertical SSF.
4.5.2
Nitrate
Figure 4.7 shows the overall performance of NO3-N removal while Figure 4.8
shows the NO3-N concentration for each treatment systems vertical and horizontal
subsurface flow (SSF) constructed wetland systems. On comparing the performance
of the two types of wetland systems, greater level of NO3-N removal was observed in
control, vegetated and vegetated with magnet for the horizontal SSF. All of the tanks
in vertical SSF system had the capability in NO3-N reductions, but in low removal
efficiencies, ranging from 66% to 70%. Contrary findings for NH4-N, thus indicated
that horizontal SSF provide good denitrification by anaerobic bacteria to nitrogen gas
(N2).
In vertical SSF, the NO3-N removal efficiency for vegetated and vegetated
with magnet treatment systems was similar which was 70%. This indicated that the
presence of magnetic field does not significantly contribute in NO3-N removal in the
wetland. However, the presence of vegetations (Limnocharis flava) had improved the
treatment efficiencies of NO3-N as shown by the greater removal efficiency of
vegetated compared to control in horizontal SSF system. This finding affirmed the
importance of wetland vegetations to provide an environment for nitrificationdenitrification in the root zone (Maehlum, 1999).
63
90
87.92
85
NO3 -N removal (%)
81.89
80
Vertical SSF
75
Horizontal SSF
69.81
70
69.81
66.42
66.04
65
60
Control
Vegetated
Vegetated with magnet
Types of treatment systems
Figure 4.7: Nitrate removal for vertical and horizontal SSF system
0.9
0.8
Concentration (C/Co)
0.7
0.6
0.5
Control
0.4
Vegetated
Vegetated
with magnet
0.3
0.2
0.1
0
0
2
4
6
8
10
Time (Days)
(a) Vertical SSF
12
14
16
18
20
64
0.9
0.8
Concentration (C/Co)
0.7
0.6
0.5
Control
0.4
Vegetated
Vegetated
with magnet
0.3
0.2
0.1
0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(b) Horizontal SSF
Figure 4.8: Comparison of NO3-N concentration (C/Co) for; (a) vertical and;
(b) horizontal SSF system with and without magnetic field
4.5.3
Phosphorus
Figure 4.9 shows the overall performance of P removal for vertical and
horizontal subsurface flow (SSF) constructed wetland systems. On comparing the
performance of the two types of wetland systems, greater level of P removal was
observed in horizontal SSF system for control, vegetated and vegetated with magnet
treatment. Generally, it shows that the percentage different for vertical and horizontal
SSF systems was not varied significantly. All of the treatment systems had the
capability in P reductions, but in lowers removal efficiencies for control and
vegetated, ranging from 50% to 62% as compared to vegetated with magnet
treatment which resulted highest removal percentage for both systems ranging from
89% to 91%.
65
100
90.91
88.64
90
P removal (%)
80
Vertical SSF
70
Horizontal SSF
61.93
60
55.49
52.27
50.19
50
40
Control
Vegetated
Vegetated with magnet
Types of treatment systems
Figure 4.9: Phosphorus removal for vertical and horizontal SSF system
Although phosphorus is required by plants microorganisms for growth, there
is no biological transformation to gas, as there is with nitrogen, and phosphorus will
consequently accumulate in wetland systems (Rosolen, 2000). Phosphorus removal
in SSF wetland can take place through precipitation and adsorption onto media
surface. Furthermore, phosphorus absorbed onto suspended sediments will be filtered
out as the suspended solids are removed. Phosphorus has a very low solubility, and is
readily moved from solution by several precipitation and adsorption reactions by
binding it in an insoluble form (Rosolen, 2000).
Removal of P was higher in horizontal SSF rather than vertical. It is well
known that phosphorus can be released under conditions of low dissolved oxygen
(Holford and Patrick, 1979; Reddy and D’Angelo, 1997; Nurnberg et al., 1987). This
was explained by the lower receivable of dissolved oxygen (DO) in horizontal SSF.
DO may be an important factor in phosphorus removal, owing to the typically
anaerobic environment and lack of mechanisms for substantial reaeration (Rosolen,
2000). Wetland plants have adapted to low DO conditions by secreting oxygen from
their roots, thus forming an aerobic area around the root. This may be important for
phosphorus retention, as suggested by Drizo et al., (1997).
66
Kim and Geary (2000) supported that soil substrates are the ultimate sinks for
phosphorus. From the result, the variation between control and vegetated P removal
shows the wetlands possibility to accumulate P in humic substances, revealed that
filtration was a significant P removal mechanism in the treatment. Since P is retained
within the wetlands, harvesting the plants and removing the saturated root bed media
achieve its ultimate removal from the system, which is not suitable because of the
short period for this study.
In spite of that, the low P removal in control and vegetated treatment if
compared to vegetated with magnet is due to media used as a substrate in this study
(coarse stone, sand and soil) generally have limited surface area for adsorption
(Davies and Cottingham, 1993). Deserved to increased surface area, longer retention
and better contact time, a finer grained soil has a greater capacity to adsorb
phosphorus (Reed et al., 1995; Vymazal, 2005a). However, a finer grained soil not
used for SSF system, at present, because of poor hydraulic conductivity.
Greater P removal in vegetated and magnet treatment for both systems were
observed. Thus, it appears that the removal of P was primarily caused by the
coagulation process. Petruska and Perumpral (1978) explained the system for
removing phosphate using magnetically conditioned coagulation is viable. After
leachate was exposed to magnetic field, the fluid undergoes coagulation to
precipitate P from the fluid to form colloids. It has been found that magnetic field of
the fluid allows P to become more readily available for coagulation, allowing the
coagulant to become more efficient. The result is that much smaller quantities of
coagulant are required. After coagulation, the precipitated P (Reddy et al., 1999)
passing through wetlands to undergo filtration.
Ferum and manganese are metals identified as the contaminants of concerns
in this study. Zhu et al., (1997) declared that a metal such as Fe and Mn correlates to
the ability of a particle to remove phosphorus. Adsorption is dependent on
composition of the material, which is oxides of these metals, while the availability of
these minerals in the soluble form will direct precipitation reactions.
67
Figure 4.10 shows the P concentration for all treatment systems. The figures
depicted substantial different P concentrations in vegetated with magnet treatment
rather than others.
1.0
0.9
Concentration (C/Co)
0.8
0.7
0.6
Control
0.5
Vegetated
0.4
Vegetated
with magnet
0.3
0.2
0.1
0.0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(a) Vertical SSF
1.0
0.9
Concentration (C/Co)
0.8
0.7
0.6
Control
0.5
Vegetated
0.4
Vegetated
with magnet
0.3
0.2
0.1
0.0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(b) Horizontal SSF
Figure 4.10: Comparison of P concentration (C/Co) for; (a) vertical and;
(b) horizontal SSF system with and without magnetic field
68
The theoretical aspects and principles of the effectiveness of vertical or
horizontal SSF systems in removing P were inconsistent among researchers. With
same installation of wetlands systems but differ in vegetation species, Breen (1990)
contended that vertical flow format maximized influent-root zone contact and
optimized conditions for nutrient absorption by plants. Contrary to the conclusion
reached by Breen, Rogers et al. (1991) findings that there was no significant
difference in P removal between vertical and horizontal flow format. Comparative
study conducted by Tanner (1994) also contrary to conclusion drawn by Breen
(1990). The results demonstrated that reduction of P were greater in horizontal flow
rather than vertical flow wetlands. Tanner et al., (1997) suggested that vertical flow
format itself would not likely increase treatment efficiency per unit of wetland
volume but rather the surface to depth ratio would determine the relative importance
of plant mediated nutrient uptake and oxygen release.
4.6 Metals Removal
In most circumstances, metals such as Fe and Mn entering wetland systems
oxidized and either bind to sediments, particulates or soluble organics, or precipitate
as insoluble salts such as sulphides and oxyhydroxides (Galbrand, 2003). Metals in
their reduced, soluble forms can also be taken up or transformed by plants and
microorganisms (Kadlec and Knight, 1996; Osmond et al., 1995).
4.6.1
Ferum
Figure 4.11 shows the overall performance of Fe removal for vertical and
horizontal SSF constructed wetland systems. The performance of the two types of
wetland systems was similar in vegetated and vegetated with magnet treatment
systems. However, greater level of Fe removal was observed in control for the
horizontal SSF which was 93% compared to vertical SSF which was 90%. Generally,
it shows that the percentage different for vertical and horizontal SSF systems was not
69
varied significantly. Fe was completely removed in vegetated with magnet treatment
while in vegetated treatment recorded 96% removal.
101
100.00
100.00
Fe removal (%)
99
96.30 96.30
97
Vertical SSF
95
Horizontal SSF
92.59
93
91
90.12
89
Control
Vegetated
Vegetated with
magnet
Types of treatment systems
Figure 4.11: Ferum removal for vertical and horizontal SSF system.
The Fe concentrations observed in the treatment wetland generally decreased
as shown in Figure 4.12. Fe is an essential micronutrient element required by both
plants and wildlife at significant concentrations (King et al., 1992). The results of
vegetated treatment system described that the Limnocharis flava as an emergent
plants play a crucial part in the treatment systems. Emergent plants help in reducing
heavy metals by retaining it either in the root or in the leaves. Capacity in
accumulating and removing heavy metals are varied according to plant species.
Uptake and accumulation of elements by plants may follow two different paths
which were in the root system and foliar surface (Sawidis et al., 2001). Nevertheless,
the result also indicated that the capability of magnetic field in both systems assist Fe
removal. The complete removal of Fe indicated the reduction of ion in the leachate
due to the aggregation effect by the magnetic fields (Wan Salida, 2005).
70
0.8
0.7
Concentration (C/Co)
0.6
0.5
Control
0.4
Vegetated
0.3
Vegetated
with magnet
0.2
0.1
0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(a) Vertical SSF
0.8
0.7
Concentration (C/Co)
0.6
0.5
Control
0.4
Vegetated
0.3
Vegetated
with magnet
0.2
0.1
0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(b) Horizontal SSF
Figure 4.12: Comparison of Fe concentration (C/Co) for; (a) vertical and;
(b) horizontal SSF system with and without magnetic field
71
4.6.2
Manganese
Figure 4.13 shows the overall performance of Mn removal and Figure 4.14
shows the concentration for vertical and horizontal subsurface flow (SSF)
constructed wetland systems. On comparing the performance of the two types of
wetland systems, greater level of Mn removal was observed in vertical SSF for all
types of treatment systems. Highest removal was observed in vegetated with magnet
treatment which was 93% (vertical SSF) and 88% (horizontal SSF), followed by
vegetated treatment which was 88% (vertical SSF) and 83% (horizontal SSF). The
lowest removal was observed in control which was 78% (vertical SSF) and 75%
(horizontal SSF).
95
92.50
Mn removal (%)
90
87.50
85
87.50
82.50
Vertical SSF
Horizontal SSF
80
77.50
75.00
75
70
Control
Vegetated
Vegetated with
magnet
Types of treatment systems
Figure 4.13: Manganese removal for vertical and horizontal SSF system
As reported primarily for Fe, Mn removal result also described the capability
of Limnocharis flava in the treatment systems. Mn oxidation required oxygen
attributed to the higher removal in vertical SSF since it retained higher dissolved
oxygen than horizontal SSF. Mn removal in vegetated were significantly high than
control tank revealed that the most effective removal mechanism for Mn in treatment
wetland systems is settling. The result also indicated that the capability of magnetic
field in both systems assist Mn removal.
72
1.0
0.9
Concentration (C/Co)
0.8
0.7
0.6
Control
0.5
Vegetated
0.4
Vegetated
with magnet
0.3
0.2
0.1
0.0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(a) Vertical SSF
1.0
0.9
Concentration (C/Co)
0.8
0.7
0.6
Control
0.5
Vegetated
0.4
Vegetated
with magnet
0.3
0.2
0.1
0.0
0
2
4
6
8
10
12
14
16
18
20
Time (Days)
(b) Horizontal SSF
Figure 4.14: Comparison of Mn concentration (C/Co) for; (a) Vertical and;
(b) Horizontal SSF system with and without magnetic field
73
4.7
ANOVA Analysis
Analysis of variance (ANOVA) has been used to reveal significant
differences for all types of treatment systems. Statistical significance differences
were tested at p≤0.05 (95% levels of significance). Table 4.3 shows the p value when
comparing significant differences between control, vegetated and vegetated with
magnet treatment systems for vertical SSF while Table 4.4 shows the p value when
comparing significant differences between control, vegetated and vegetated with
magnet treatment systems for horizontal SSF. Table 4.5 shows the p value between
vertical and horizontal SSF systems for the three treatment systems.
Table 4.3: Significant differences between control, vegetated and vegetated with
magnet treatment systems for vertical SSF
ANOVA Two Factor Without Replication
95% levels of significance
p value
Parameters
Significant
p ≤ 0.05
TSS
1.354E-08
Turbidity
1.558E-06
NH4-N
4.234E-06
NO3-N
2.018E-11
P
8.929E-12
Fe
5.798E-10
Mn
2.076E-09
Table 4.4: Significant differences between control, vegetated and vegetated with
magnet treatment systems for horizontal SSF
ANOVA Two Factor Without Replication
95% levels of significance
p value
Parameters
Significant
p ≤ 0.05
TSS
1.354E-08
Turbidity
6.544E-08
NH4-N
1.227E-06
5.525E-08
NO3-N
P
2.299E-10
Fe
1.678E-13
Mn
4.532E-07
74
Table 4.5: ANOVA Analysis Comparing Vertical and Horizontal SSF for
Control, Vegetated and Vegetated with Magnet Treatment Systems
Parameters
ANOVA Two Factor Without Replication
95% levels of significance
p value
Control
Vegetated
Vegetated with Magnet
Not
Not
Not
Significant
Significant
Significant
significant
significant
significant
p ≤ 0.05
p ≤ 0.05
p ≤ 0.05
p ≥ 0.05
p ≥ 0.05
p ≥ 0.05
TSS
0.0313
0.0046
0.1768
Turbidity
0.0493
0.3524
0.5931
NH4-N
0.6174
0.2611
0.3173
NO3-N
0.1193
0.3744
0.5918
P
0.0736
0.1160
0.8672
Fe
0.0448
0.2396
0.0395
Mn
0.0076
0.0039
4.8
Uptake by Plant
Wetland plants have been successfully used to phytoremediate trace elements
in natural and constructed wetlands (Ying, 2003). In the study, physical uptake of Fe
and Mn by plant roots and their subsequent accumulation in leaves was investigated
for both vertical and horizontal SSF treatment systems. Figure 4.15 showed the
heavy metal uptake by plant’s roots and leaves for Fe while Figure 4.16 showed the
uptake for Mn, respectively.
From both systems, the uptake of Fe by plants increased with increasing
metal concentration. As a general rule, uptake of metals by plants will only occur if
they are bioavailable, which means absorbable by roots. Iron and manganese are
metals which tend to moderately bioavailable in wetlands environment (Galbrand,
2003). This study proofs that Limnocharis flava had availability in heavy metal
uptake by root and leaves.
75
2000
1785
1800
1716
Fe.conc (ug/g dry weight)
1600
1344
1400
1200
1000
Leaves
800
Root
600
400
313
296
316
200
0
Initial plants
Vegetated
Vegetated with magnet
(a) vertical SSF
2000
1800
Fe conc.(ug/g dry weight)
1600
1406
1403
1344
1400
1200
1000
Leaves
800
Root
600
400
296
310
311
200
0
Initial plants
Vegetated
Vegetated with magnet
(b) horizontal SSF
Figure 4.15: Fe uptake by root and leaves for (a) vertical and; (b) horizontal
SSF system.
As compared to Fe, uptake of Mn resulted in the similar trend. Accumulation
of metals relatively higher in vertical SSF system because vertical flow format
retained higher dissolved oxygen than horizontal SSF for Mn oxidation. Heavy
metals were accumulated more in roots compared to leaves as mention by Peverly et
al., (1995).
76
4.0
3.5
Mn conc.(ug/g dry weight)
3.0
2.5
2.28
2.18
2.0
1.83
Leaves
1.5
1.48
1.47
1.42
Root
1.0
0.5
0.0
Initial plants
Vegetated
Vegetated with magnet
(a) vertical SSF
4.0
3.37
3.5
Mn conc.(ug/g dry weight)
3.0
2.5
2.0
1.5
1.89
1.83
1.42
1.46
1.47
Leaves
Root
1.0
0.5
0.0
Initial plants
Vegetated
Vegetated with magnet
(b) horizontal SSF
Figure 4.16: Mn uptake by root and leaves for (a) vertical and; (b) horizontal
SSF system
However, it was observed that Limnhocharis flava accumulate more Fe
compared to Mn. Study done by Skousen et al. (1994) and Stark et al. (1994) on
constructed wetland revealed less successful in removing manganese. This is mostly
due to the fact that oxidized manganese does not readily form precipitate unless the
77
pH of waters is at least 7.0 (Galbrand, 2003). In addition, Mn oxidation is sensitive to
the presence of Fe2+, which can prevent or even reverse Mn oxidation (Skousen et
al., 1994).
Table 4.6: Accumulation of Fe in leaves and roots
Accumulation of ferum (%)
Vertical SSF Horizontal SSF
Leaves Root Leaves Root
Vegetated
5.6
27.7
4.6
4.4
Vegetated with magnet
6.7
32.8
5.1
4.6
Table 4.7: Accumulation of Mn in leaves and roots
Accumulation of manganese (%)
Vertical SSF Horizontal SSF
Leaves Root Leaves Root
Vegetated
4.0
19.1
2.9
3.1
Vegetated with magnet
4.8
24.6
4.2
4.2
Table 4.6 and Table 4.7 shows the percentage of Fe and Mn accumulated in
leaves and roots for both systems. The percentage of accumulation for Fe and Mn in
leaves and roots for both systems were relatively low and not exceeded 50% of initial
values. Hence, Fe and Mn removal via uptake by Limnocharis flava leaves and roots
is typically ineffective and predominant metals removal mechanism to the
precipitation-adsorption phenomena in the substrate.
4.9
Physical Appearance of Plants
Both systems were vegetated with equal distributed of plants clusters and
leaves. The experiments were carried out with 6 clusters of Limnocharis flava and a
23 pieces of leaves for each vegetated tank. Table 4.8, Figure 4.17, Figure 4.18 and
Figure 4.19 showed the physical appearance of plants in vertical SSF constructed
wetlands while Table 4.9, Figure 4.20, Figure 4.21 and Figure 4.22 showed the
78
physical appearance of plants in horizontal SSF constructed wetlands for 18 days of
experiment.
Table 4.8: Amount or partial and complete wilting of plant’s leaves in vegetated
and vegetated with magnet treatment in vertical SSF constructed wetlands
Duration of experiment (Days)
6
Treatment systems
Vegetated
Vegetated with magnet
Complete wilting – none Complete wilting – none
Partial wilting – none
Partial wilting – none
12
Complete wilting – 1
Partial wilting – 2
Complete wilting – 2
Partial wilting – 1
18
Complete wilting – 4
Partial wilting – 3
Complete wilting – 4
Partial wilting – 4
Table 4.9: Amount or partial and complete wilting of plant’s leaves in vegetated
and vegetated with magnet treatment in horizontal SSF constructed wetlands.
Duration of experiment (Days)
6
Treatment systems
Vegetated
Vegetated with magnet
Complete wilting – none Complete wilting – none
Partial wilting – none
Partial wilting – none
12
Complete wilting –3
Partial wilting – 3
Complete wilting – 3
Partial wilting – 1
18
Complete wilting –1
Partial wilting – 2
Complete wilting – 4
Partial wilting – 1
(a)
(b)
Figure 4.17: Physical appearance of plants in (a) vegetated and; (b) vegetated
with magnet after 6 days of treatment in vertical SSF
79
(a)
(b)
Figure 4.18: Physical appearance of plants in (a) vegetated and; (b) vegetated
with magnet after 12 days of treatment in vertical SSF
(a)
(b)
Figure 4.19: Physical appearance of plants in (a) vegetated and; (b) vegetated
with magnet after 18 days of treatment in vertical SSF
(a)
(b)
Figure 4.20: Physical appearance of plants in (a) vegetated and; (b) vegetated
with magnet after 6 days of treatment in horizontal SSF
80
(a)
(b)
Figure 4.21: Physical appearance of plants in (a) vegetated and; (b) vegetated
with magnet after 12 days of treatment in horizontal SSF
(a)
(b)
Figure 4.22: Physical appearance of plants in (a) vegetated and; (b) vegetated
with magnet after 18 days of treatment in horizontal SSF
After proceeding with the treatment process, one of the most important
aspects to be considered is that, the plants were allowed to climatised with the
environment. Though there were fully and partial leaves wilting but at the same time
there were some new plant was seen growing. This is because the plant need some
time to adapt to the environment and stabilize (Ernest and Andrew, 2002). In spite of
that, Rosolen (2000) explained the nutrients are released when the plants die, and the
phosphorus cycles back into the system and becomes available for new growth. After
about 18 days of experiments the plants were fully adapted to the new environment
and leaves were seen growing fertile. Galbrand (2003) elaborated Fe and Mn was
micronutrient to plant. Plant will grow fertile until heavy metal exceeded toxic
amounts that can be toxic to plant and resulted in inhibited grow by plants.
81
4.10
Conclusion
From the results and analysis, the constructed wetland vegetated with
Limnocharis flava have shown their ability to remove suspended solid (TSS),
turbidity, nitrate (NO3-N), phosphorus (P), ammoniacal nitrogen (NH4-N), ferum (Fe)
and manganese (Mn) from leachate. The leachate concentration used in this
experiment was 50%. Study done by Hui (2005) had revealed that 50% leachate
concentration will give the highest removal efficiency in removing NO3-N and Mn.
The vegetated with magnetic field treatment also have their capability in
treating leachate. TSS, turbidity, NO3-N, P and heavy metals removal have shown
that magnetic field posed a great role in their removal. For magnet system, 6 set of
permanent magnet was used with strength 0.55 Tesla. The circulation was 1.8 mL/s
for duration of 6 hours. Johan (2003) had revealed that the flowrate 1.8 mL/s will
give the optimum precipitation of TSS in wastewater. Zulfa et al., (2005) revealed
that 6 hours of exposure to the magnetic field was the optimum time to precipitate
the TSS in leachate.
The treatability of vertical and horizontal SSF flow regime also shows pros
and cons between each others. Horizontal SSF systems cannot provide good
nitrification because of their limited oxygen transfer capacity. Vertical SSF systems,
on the other hand, do provide a good condition for nitrification but no denitrification
occurs in this systems. An overall, horizontal SSF system shows greater removal in
all parameters except ammoniacal nitrogen and manganese.
CHAPTER 5
CONCLUSIONS
5.1
Conclusions
The capability of emergent plant Limnocharis flava in the removal of all
parameters did show a performance compared to unplanted control. Presence of the
vegetation did show there was a substantial removal shown for nutrients (NH4N>80%, NO3-N>70% and P>55%) and heavy metals (Fe>96 and Mn>83%). The
macrophyte plays an important role in constructed wetlands by providing microbial
attachments, trapping and settlement of suspended components. The capability of
emergent plant has lower removal efficiency in TSS (<48%) and turbidity (<65). The
factors likely to influence the TSS and turbidity removal are physical filtration and
sedimentation within the pores of the substrate in the constructed wetlands.
Constructed wetland with magnetic field had a greater ability than vegetated
treatment in removal of TSS, turbidity, P and heavy metals. For those parameters,
highest removal was recorded in both systems compared to other treatment which
was >86% for TSS, >87% for turbidity, >89% for P, complete removal for Fe and for
Mn, removal was >88%. Electrically contribute to a greater ionic charge or extra
energy when exposed to magnetic field. This energy will make the charged particles
to vibrate excessively. Thus more particles are colliding among themselves (Johan et
al., 2004). This reaction contributes to additional number of ions (positive and
83
negative charge), which consequently creates a natural magnetic attraction between
the opposite charged particles. Particles are then attracted and agglomerated. This
phenomenon intensifies coagulation that enables them to flocculate and precipitate
when become heavier. As a result particles passing through wetlands were enhanced
the removal of mentioned parameters by filtration, sedimentation, adsorption and
precipitation.
The effect of different flow format used in this study had shown that vertical
flow format do provide a good condition for nitrification but no denitrification. On
the other hand, horizontal flow format cannot provide nitrification because of their
limited oxygen transfer capacity. The treatability of vertical SSF had showed greater
removal in ammoniacal nitrogen (>87%) and Mn (>78%) while horizontal flow had
showed greater removal of nitrate (>66%) and phosphorus (52%). Others parameters
did not contribute to substantial differences between vertical and horizontal SSF
constructed wetlands.
As far as removal mechanisms are concerned, it is generally agreed by this
study that uptake of metals by Limnocharis flava is insignificant compared to the
other removal pathways. The metals uptake by plant’s leaves and root were relatively
low when the percentage accumulation of metals not exceeded 50% when compared
to initial value. This situation can be concluded that removal via uptake by
Limnocharis flava leaves and roots is typically ineffective and predominant metals
removal mechanism to the precipitation-adsorption phenomena in the substrate.
5.2
Recommendations
Magnetic fields had shown great potential in enhancing removal of some
parameters. However, there were pro and contras of applying vertical and horizontal
SSF system into wetlands. In order for further enhanced the findings of this study,
some recommendations are as follows:
84
(i)
Various types of constructed wetlands may be combined in order to
achieve higher treatment effect, especially for nitrogen;
(ii)
Arranging vertical SSF and horizontal SSF in a stage manner in order
to improved the treatment efficiency;
(iii)
The use of plant types other than Limnocharis flava such as reeds and
bulrushes should be investigated to determine if optimum species
exists;
(iv)
Longer period of the test is necessary to determine the fullest capacity
of the SSF constructed wetlands in pollutant removal.
(v)
To study the effect of pH in the removal of heavy metals in wetlands.
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APPENDIX
99
APPENDIX A
Raw Data
Table A1: Initial condition of leachate
Parameters
mg/L*
TSS
73.6
Turbidity
120
-
NH4 N
136
NO3-N
26.5
P
52.8
Fe
0.81
Mn
0.4
* Except for turbidity (FTU)
Table A2: Removal of TSS for vertical and horizontal SSF systems
Time
(Days)
Sample
Effluent
(Vertical)
mg/L
Removal
Removal
efficiency
(Vertical)
Effluent
(Horizontal)
mg/L
Removal
Removal
efficiency
(Horizontal)
3
C1
P1
M1
C2
P2
M2
C3
P3
M3
C4
P4
M4
C5
P5
M5
C6
P6
M6
70.67
66.50
50.50
66.90
62.90
41.20
62.80
56.30
25.90
59.60
50.20
20.20
49.30
46.80
12.35
41.30
38.50
10.01
2.93
7.10
23.10
6.70
10.70
32.40
10.80
17.30
47.70
14.00
23.40
53.40
24.30
26.80
61.25
32.30
35.10
63.59
3.98
9.65
31.39
9.10
14.54
44.02
14.67
23.51
64.81
19.02
31.79
72.55
33.02
36.41
83.22
43.89
47.69
86.40
69.30
62.80
52.00
66.30
59.60
39.67
60.30
52.60
20.10
52.30
45.80
18.37
44.00
40.70
12.83
39.50
38.00
7.33
4.30
10.80
21.60
7.30
14.00
33.93
13.30
21.00
53.50
21.30
27.80
55.23
29.60
32.90
60.77
34.10
35.60
66.27
5.84
14.67
29.35
9.92
19.02
46.10
18.07
28.53
72.69
28.94
37.77
75.04
40.22
44.70
82.57
46.33
48.37
90.04
6
9
12
15
18
100
APPENDIX A
Raw Data
Table A3: Removal of Turbidity for vertical and horizontal SSF systems
Time
(Days)
Sample
Effluent
(Vertical)
mg/L
Removal
Removal
efficiency
(Vertical)
Effluent
(Horizontal)
mg/L
Removal
Removal
efficiency
(Horizontal)
3
C1
P1
M1
C2
P2
M2
C3
P3
M3
C4
P4
M4
C5
P5
M5
C6
P6
M6
74.00
66.00
97.00
70.00
63.00
64.00
68.00
56.00
49.00
63.00
46.00
35.00
55.00
44.00
22.00
48.00
43.00
16.00
46.00
54.00
23.00
50.00
57.00
56.00
52.00
64.00
71.00
57.00
74.00
85.00
65.00
76.00
98.00
72.00
77.00
104.00
38.33
45.00
19.17
41.67
47.50
46.67
43.33
53.33
59.17
47.50
61.67
70.83
54.17
63.33
81.67
60.00
64.17
86.67
75.00
62.00
90.00
67.00
57.00
63.00
59.00
51.00
53.00
55.00
49.00
46.00
52.00
47.00
27.00
46.00
42.00
13.00
45.00
58.00
30.00
53.00
63.00
57.00
61.00
69.00
67.00
65.00
71.00
74.00
68.00
73.00
93.00
74.00
78.00
107.00
37.50
48.33
25.00
44.17
52.50
47.50
50.83
57.50
55.83
54.17
59.17
61.67
56.67
60.83
77.50
61.67
65.00
89.17
6
9
12
15
18
Table A4: Removal of NH4-N for vertical and horizontal SSF systems
Time
(Days)
Sample
Effluent
(Vertical)
mg/L
Removal
Removal
efficiency
(Vertical)
Effluent
(Horizontal)
mg/L
Removal
Removal
efficiency
(Horizontal)
3
C1
P1
M1
C2
P2
M2
C3
P3
M3
C4
P4
M4
C5
P5
M5
C6
P6
M6
124.50
91.40
99.75
84.60
89.60
90.60
73.80
55.20
68.20
28.26
13.11
21.40
27.70
11.50
15.67
18.02
8.01
8.28
11.50
44.60
36.25
51.40
46.40
45.40
62.20
80.80
67.80
107.74
122.89
114.60
108.30
124.50
120.33
117.98
127.99
127.72
8.46
32.79
26.65
37.79
34.12
33.38
45.74
59.41
49.85
79.22
90.36
84.26
79.63
91.54
88.48
86.75
94.11
93.91
122.60
123.40
109.30
73.80
71.20
69.80
65.40
45.95
59.30
44.15
33.95
47.60
37.15
28.05
39.30
28.05
26.70
32.20
13.40
12.60
26.70
62.20
64.80
66.20
70.60
90.05
76.70
91.85
102.05
88.40
98.85
107.95
96.70
107.95
109.30
103.80
9.85
9.26
19.63
45.74
47.65
48.68
51.91
66.21
56.40
67.54
75.04
65.00
72.68
79.38
71.10
79.38
80.37
76.32
6
9
12
15
18
101
APPENDIX A
Raw Data
Table A5: Removal of NO3-N for vertical and horizontal SSF systems
Time
(Days)
Sample
Effluent
(Vertical)
mg/L
Removal
Removal
efficiency
(Vertical)
Effluent
(Horizontal)
mg/L
Removal
Removal
efficiency
(Horizontal)
3
C1
P1
M1
C2
P2
M2
C3
P3
M3
C4
P4
M4
C5
P5
M5
C6
P6
M6
15.00
13.60
12.80
11.80
11.20
10.90
15.00
13.50
13.40
9.20
8.00
6.00
9.00
4.80
4.20
9.00
8.00
8.00
11.50
12.90
13.70
14.70
15.30
15.60
11.50
13.00
13.10
17.30
18.50
20.50
17.50
21.70
22.30
17.50
18.50
18.50
43.40
48.68
51.70
55.47
57.74
58.87
43.40
49.06
49.43
65.28
69.81
77.36
66.04
81.89
84.15
66.04
69.81
69.81
18.20
15.10
15.60
21.00
18.30
17.30
17.20
13.20
11.20
11.80
10.20
9.80
8.20
5.60
4.00
8.90
4.80
3.20
8.30
11.40
10.90
5.50
8.20
9.20
9.30
13.30
15.30
14.70
16.30
16.70
18.30
20.90
22.50
17.60
21.70
23.30
31.32
43.02
41.13
20.75
30.94
34.72
35.09
50.19
57.74
55.47
61.51
63.02
69.06
78.87
84.91
66.42
81.89
87.92
6
9
12
15
18
Table A6: Removal of P for vertical and horizontal SSF systems
Time
(Days)
Sample
Effluent
(Vertical)
mg/L
Removal
Removal
efficiency
(Vertical)
Effluent
(Horizontal)
mg/L
Removal
Removal
efficiency
(Horizontal)
3
C1
P1
M1
C2
P2
M2
C3
P3
M3
C4
P4
M4
C5
P5
M5
C6
P6
M6
41.50
36.80
26.00
39.60
37.00
20.20
32.50
24.30
13.60
37.60
29.60
14.50
34.20
23.90
13.60
26.30
23.50
6.00
11.30
16.00
26.80
13.20
15.80
32.60
20.30
28.50
39.20
15.20
23.20
38.30
18.60
28.90
39.20
26.50
29.30
46.80
21.40
30.30
50.76
25.00
29.92
61.74
38.45
53.98
74.24
28.79
43.94
72.54
35.23
54.73
74.24
50.19
55.49
88.64
47.20
42.00
23.50
45.00
38.00
27.60
42.30
36.50
14.90
37.80
33.00
11.60
36.50
29.80
9.70
25.20
20.10
4.80
5.60
10.80
29.30
7.80
14.80
25.20
10.50
16.30
37.90
15.00
19.80
41.20
16.30
23.00
43.10
27.60
32.70
48.00
10.61
20.45
55.49
14.77
28.03
47.73
19.89
30.87
71.78
28.41
37.50
78.03
30.87
43.56
81.63
52.27
61.93
90.91
6
9
12
15
18
102
APPENDIX A
Raw Data
Table A7: Removal of Fe for vertical and horizontal SSF systems
Time
(Days)
Sample
Effluent
(Vertical)
mg/L
Removal
Removal
efficiency
(Vertical)
Effluent
(Horizontal)
mg/L
Removal
Removal
efficiency
(Horizontal)
3
C1
P1
M1
C2
P2
M2
C3
P3
M3
C4
P4
M4
C5
P5
M5
C6
P6
M6
0.55
0.44
0.38
0.43
0.28
0.24
0.27
0.24
0.23
0.17
0.11
0.12
0.09
0.06
0.01
0.08
0.03
0.00
0.26
0.37
0.43
0.38
0.53
0.57
0.54
0.57
0.58
0.64
0.70
0.69
0.72
0.75
0.80
0.73
0.78
0.81
32.10
45.68
53.09
46.54
65.43
70.37
66.67
70.37
71.60
79.01
86.42
85.19
88.89
92.59
98.77
90.12
96.30
100.00
0.35
0.35
0.27
0.33
0.28
0.18
0.15
0.11
0.08
0.11
0.11
0.06
0.10
0.08
0.00
0.06
0.03
0.00
0.46
0.46
0.54
0.48
0.53
0.63
0.66
0.70
0.73
0.70
0.70
0.75
0.71
0.73
0.81
0.75
0.78
0.81
56.79
56.79
66.67
59.26
65.43
77.78
81.48
86.42
90.12
86.42
86.42
92.59
87.65
90.12
100.00
92.59
96.30
100.00
6
9
12
15
18
Table A8: Removal of Mn for vertical and horizontal SSF systems
Time
(Days)
Sample
Effluent
(Vertical)
mg/L
Removal
Removal
efficiency
(Vertical)
Effluent
(Horizontal)
mg/L
Removal
Removal
efficiency
(Horizontal)
3
C1
P1
M1
C2
P2
M2
C3
P3
M3
C4
P4
M4
C5
P5
M5
C6
P6
M6
0.27
0.27
0.25
0.24
0.23
0.19
0.18
0.15
0.13
0.16
0.13
0.11
0.11
0.09
0.07
0.09
0.05
0.03
0.13
0.13
0.15
0.16
0.17
0.21
0.22
0.25
0.27
0.24
0.27
0.29
0.29
0.31
0.33
0.31
0.35
0.37
32.50
32.50
37.50
40.00
42.50
52.50
55.00
62.50
67.50
60.00
67.50
72.50
72.50
77.50
82.50
77.50
87.50
92.50
0.33
0.32
0.25
0.30
0.29
0.23
0.29
0.26
0.20
0.20
0.19
0.16
0.19
0.15
0.10
0.10
0.07
0.05
0.07
0.08
0.15
0.10
0.11
0.17
0.11
0.14
0.20
0.20
0.21
0.24
0.21
0.25
0.30
0.30
0.33
0.35
17.50
20.00
37.50
25.00
27.50
42.50
27.50
35.00
50.00
50.00
52.50
60.00
52.50
62.50
75.00
75.00
82.50
87.50
6
9
12
15
18
103
APPENDIX A
Raw Data
Table A9: Ferum uptake by plants in roots and leaves
Initial plants
Vegetated
Vegetated with magnet
Vertical SSF
Leaves
Roots
296.0
1344.0
312.6
1716.0
315.9
1785.2
Horizontal SSF
Leaves
Roots
296.0
1344.0
309.6
1403.0
311.2
1406.0
Table A10: Manganese uptake by plants in roots and leaves
Initial plants
Vegetated
Vegetated with magnet
Vertical SSF
Leaves
Roots
1.42
1.83
1.47
2.18
1.48
2.28
Horizontal SSF
Leaves
Roots
1.42
1.83
1.46
1.89
1.47
3.37
104
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B1: Result of ANOVA for TSS in vertical SSF
Time
Control
Vegetated Vegetated
with
(Days)
(%)
(%)
magnet
(%)
3
3.98
9.65
31.39
6
9.10
14.54
44.02
9
14.67
23.51
64.81
12
19.02
31.79
72.55
15
33.02
36.41
83.22
18
43.89
47.69
86.40
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
4
4
4
4
4
4
Sum
48.01358696
73.66304348
111.9891304
135.3695652
167.6494565
195.9755435
Average
12.00339674
18.41576087
27.99728261
33.8423913
41.91236413
48.99388587
Variance
175.5514797
303.858863
637.9152587
733.1851371
846.6625038
795.8630197
6
6
6
6
63
123.6820652
163.5869565
382.3913043
10.5
20.61367754
27.26449275
63.73188406
31.5
228.4743042
201.5792376
481.472388
df
MS
782.2797353
3225.125938
53.58206479
F
14.5996564
60.19040048
ANOVA
Source of
Variation
Rows
Columns
Error
SS
3911.398677
9675.377814
803.7309718
Total
14390.50746
5
3
15
23
P-value
2.63E-05
1.354E-08
F crit
2.9012945
3.2873821
APPENDIX B
Varian Analysis Calculation (ANOVA)
105
Table B2: Result of ANOVA for TSS in horizontal SSF
Time
Control
Vegetated
(Days)
(%)
(%)
3
6
9
12
15
18
5.84
9.92
18.07
28.94
40.22
46.33
14.67
19.02
28.53
37.77
44.70
48.37
Vegetated
with
magnet
(%)
29.35
46.10
72.69
75.04
82.57
90.04
4
4
4
4
4
4
Sum
52.86413043
81.04076087
128.2934783
153.7527174
182.486413
202.7418478
Average
13.21603261
20.26019022
32.07336957
38.43817935
45.62160326
50.68546196
Variance
140.3660282
326.5205497
796.9072641
709.7939084
777.5889521
880.4997163
6
6
6
6
63
149.3206522
193.0706522
395.7880435
10.5
24.88677536
32.17844203
65.96467391
31.5
268.9066684
188.6107091
543.6623494
df
MS
844.2746227
3317.667912
62.80170141
F
13.4434992
52.82767564
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
ANOVA
Source of
Variation
Rows
Columns
Error
SS
4221.373113
9953.003735
942.0255211
Total
15116.40237
5
3
15
23
P-value
4.297E-05
3.31E-08
F crit
2.9012945
3.2873821
APPENDIX B
Varian Analysis Calculation (ANOVA)
106
Table B3: Result of ANOVA for Turbidity in vertical SSF
Time
Control
Vegetated
Vegetated
with
magnet
(%)
(Days)
(%)
(%)
3
6
9
12
15
18
38.33
41.67
43.33
47.50
54.17
60.00
45.00
41.67
43.33
47.50
54.17
60.00
19.17
46.67
59.17
70.83
81.67
86.67
4
4
4
4
4
4
Sum
105.5
136
154.8333333
177.8333333
205
224.6666667
Average
26.375
34
38.70833333
44.45833333
51.25
56.16666667
Variance
362.7476852
354
447.9699074
589.2291667
752.0833333
805.4444444
6
6
6
6
63
285
291.6666667
364.1666667
10.5
47.5
48.61111111
60.69444444
31.5
67.22222222
50.18518519
628.1712963
df
MS
488.8761574
2831.13696
96.06751543
F
5.088881035
29.47028397
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
ANOVA
Source of
Variation
Rows
Columns
Error
Total
Count
SS
2444.380787
8493.41088
1441.012731
12378.8044
5
3
15
23
P-value
0.0063168
1.558E-06
F crit
2.9012945
3.2873821
APPENDIX B
Varian Analysis Calculation (ANOVA)
107
Table B4: Result of ANOVA for Turbidity in horizontal SSF
Time
Control
Vegetated
Vegetated
with
magnet
(%)
(Days)
(%)
(%)
3
6
9
12
15
18
37.50
44.17
50.83
54.17
56.67
61.67
48.33
52.50
57.50
59.17
60.83
65.00
25.00
47.50
55.83
61.67
77.50
89.17
4
4
4
4
4
4
Sum
113.8333333
150.1666667
173.1666667
187
210
233.8333333
Average
28.45833333
37.54166667
43.29166667
46.75
52.5
58.45833333
Variance
378.9513889
453.8958333
530.6550926
546.4166667
706.0185185
877.6550926
6
6
6
6
63
305
343.3333333
356.6666667
10.5
50.83333333
57.22222222
59.44444444
31.5
76.94444444
35.74074074
511.2962963
df
MS
456.8888889
3162.604938
66.19753086
F
6.901902275
47.77527042
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
ANOVA
Source of
Variation
Rows
Columns
Error
SS
2284.444444
9487.814815
992.962963
Total
12765.22222
5
3
15
23
P-value
0.0015744
6.544E-08
F crit
2.9012945
3.2873821
108
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B5: Result of ANOVA for ammoniacal nitrogen in vertical SSF
Time
Control
Vegetated
(Days)
(%)
(%)
3
6
9
12
15
18
8.46
37.79
45.74
79.22
79.63
86.75
32.79
34.12
59.41
90.36
91.54
94.11
Vegetated
with
magnet
(%)
26.65
33.38
49.85
84.26
88.48
93.91
4
4
4
4
4
4
Sum
70.90441176
111.2941176
164
265.8455882
274.6544118
292.7720588
Average
17.72610294
27.82352941
41
66.46139706
68.66360294
73.19301471
Variance
203.1849544
215.3985006
487.9302191
1338.985272
1305.407237
1365.619967
6
6
6
6
63
337.5882353
402.3382353
376.5441176
10.5
56.26470588
67.05637255
62.75735294
31.5
948.017474
838.3877739
885.5098183
df
MS
2213.786963
4100.479311
163.2093678
F
13.56409251
25.12404384
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
ANOVA
Source of
Variation
Rows
Columns
Error
SS
11068.93481
12301.43793
2448.140517
Total
25818.51326
5
3
15
23
P-value
4.076E-05
4.234E-06
F crit
2.9012945
3.2873821
109
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B6: Result of ANOVA for ammoniacal nitrogen in horizontal SSF
Time
Control
Vegetated
(Days)
(%)
(%)
3
6
9
12
15
18
9.85
45.74
51.91
67.54
72.68
79.38
9.26
47.65
66.21
75.04
79.38
80.37
Vegetated
with
magnet
(%)
19.63
48.68
56.40
65.00
71.10
76.32
4
4
4
4
4
4
Sum
41.75
148.0588235
183.5220588
219.5735294
238.1617647
254.0661765
Average
10.4375
37.01470588
45.88051471
54.89338235
59.54044118
63.51654412
Variance
47.19296064
429.0014418
640.1885227
835.8656466
894.5668433
923.7416513
6
6
6
6
63
327.0955882
357.9044118
337.1323529
10.5
54.51593137
59.65073529
56.18872549
31.5
639.2503334
756.1747135
419.6656935
df
MS
1528.798479
3240.903297
105.9307538
F
14.43205513
30.59454579
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
ANOVA
Source of
Variation
Rows
Columns
Error
SS
7643.992395
9722.709892
1588.961307
Total
18955.66359
5
3
15
23
P-value
2.818E-05
1.227E-06
F crit
2.9012945
3.2873821
110
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B7: Result of ANOVA for nitrate in vertical SSF
Time
Control
Vegetated Vegetated
with
(Days)
(%)
(%)
magnet
(%)
3
6
9
12
15
18
43.40
55.47
43.40
65.28
66.04
66.04
48.68
57.74
49.06
69.81
81.89
69.81
51.70
58.87
49.43
77.36
84.15
69.81
4
4
4
4
4
4
Sum
146.7735849
178.0754717
150.8867925
224.4528302
247.0754717
223.6603774
Average
36.69339623
44.51886792
37.72169811
56.11320755
61.76886792
55.91509434
Variance
516.324997
661.4172303
374.2644773
889.6869586
1037.079477
642.077489
6
6
6
6
63
339.6226415
376.9811321
391.3207547
10.5
56.60377358
62.83018868
65.22012579
31.5
120.6977572
175.3079388
199.838614
df
MS
447.9400291
3988.510161
26.46809363
F
16.92377378
150.6912518
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
ANOVA
Source of
Variation
Rows
Columns
Error
SS
2239.700145
11965.53048
397.0214044
Total
14602.25203
5
3
15
23
P-value
1.07E-05
2.018E-11
F crit
2.9012945
3.2873821
APPENDIX B
Varian Analysis Calculation (ANOVA)
111
Table B8: Result of ANOVA for nitrate in horizontal SSF
Time
Control
Vegetated
Vegetated
with
magnet
(%)
(Days)
(%)
(%)
3
6
9
12
15
18
31.32
20.75
35.09
55.47
69.06
66.42
43.02
30.94
50.19
61.51
78.87
81.89
41.13
34.72
57.74
63.02
84.91
87.92
4
4
4
4
4
4
Sum
118.4716981
92.41509434
152.0188679
192
247.8301887
254.2264151
Average
29.61792453
23.10377358
38.00471698
48
61.95754717
63.55660377
Variance
341.1914976
164.7944702
462.503471
586.6324908
1022.661534
1004.45556
6
6
6
6
63
278.1132075
346.4150943
369.4339623
10.5
46.35220126
57.73584906
61.57232704
31.5
401.8179661
407.0914916
478.9414976
df
MS
1120.291518
3250.473295
66.35314564
F
16.88377405
48.98747849
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
ANOVA
Source of
Variation
Rows
Columns
Error
SS
5601.457592
9751.419885
995.2971846
Total
16348.17466
5
3
15
23
P-value
1.085E-05
5.525E-08
F crit
2.9012945
3.2873821
112
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B9: Result of ANOVA for phosphorus in vertical SSF
Time
Control
Vegetated
Vegetated
with
magnet
(%)
(Days)
(%)
(%)
3
6
9
12
15
18
21.40
25.00
38.45
28.79
35.23
50.19
30.30
29.92
53.98
43.94
54.73
55.49
50.76
61.74
74.24
72.54
74.24
88.64
4
4
4
4
4
4
Sum
105.4621212
122.6666667
175.6666667
157.2651515
179.2045455
212.3181818
Average
26.3655303
30.66666667
43.91666667
39.31628788
44.80113636
53.07954545
Variance
393.6884135
535.6031527
756.6528543
660.6913979
648.411554
836.3455961
6
6
6
6
63
199.0530303
268.3712121
422.1590909
10.5
33.17550505
44.72853535
70.35984848
31.5
109.2374981
145.8823558
165.4865416
df
MS
385.8960366
3721.042371
22.0701196
F
17.48499979
168.6009155
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
ANOVA
Source of
Variation
Rows
Columns
Error
SS
1929.480183
11163.12711
331.051794
Total
13423.65909
5
3
15
23
P-value
8.739E-06
8.929E-12
F crit
2.9012945
3.2873821
APPENDIX B
Varian Analysis Calculation (ANOVA)
113
Table B10: Result of ANOVA for phosphorus in horizontal SSF
Time
Control
Vegetated
Vegetated
with
magnet
(%)
(Days)
(%)
(%)
3
6
9
12
15
18
10.61
14.77
19.89
28.41
30.87
52.27
20.45
28.03
30.87
37.50
43.56
61.93
55.49
47.73
71.78
78.03
81.63
90.91
4
4
4
4
4
4
Sum
89.5530303
96.53030303
131.5378788
155.9393939
171.0606061
223.1136364
Average
22.38825758
24.13257576
32.8844697
38.98484848
42.76515152
55.77840909
Variance
538.1165968
329.4330234
752.1192369
788.9269972
807.7948041
903.8424156
6
6
6
6
63
156.8181818
222.3484848
425.5681818
10.5
26.13636364
37.05808081
70.9280303
31.5
224.0157254
211.327288
268.2901458
df
MS
625.2308621
3937.062579
36.63409904
F
17.06690975
107.4698896
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
ANOVA
Source of
Variation
Rows
Columns
Error
SS
3126.154311
11811.18774
549.5114856
Total
15486.85353
5
3
15
23
P-value
1.015E-05
2.299E-10
F crit
2.9012945
3.2873821
APPENDIX B
Varian Analysis Calculation (ANOVA)
114
Table B11: Result of ANOVA for ferum in vertical SSF
Time
Control
Vegetated
Vegetated
with
magnet
(%)
(Days)
(%)
(%)
3
6
9
12
15
18
32.10
46.54
66.67
79.01
88.89
90.12
45.68
65.43
70.37
86.42
92.59
96.30
53.09
70.37
71.60
85.19
98.77
100.00
4
4
4
4
4
4
Sum
133.8641975
188.345679
217.6419753
262.617284
295.2469136
304.4197531
Average
33.46604938
47.08641975
54.41049383
65.65432099
73.8117284
76.10493827
Variance
488.0550094
855.69842
920.8977671
1289.96027
1553.849451
1517.122542
6
6
6
6
63
403.3333333
456.7901235
479.0123457
10.5
67.22222222
76.13168724
79.83539095
31.5
558.9010822
371.6913072
333.2825281
df
MS
1095.378836
6292.256658
66.66536055
F
16.43100445
94.38569905
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
ANOVA
Source of
Variation
Rows
Columns
Error
SS
5476.894179
18876.76997
999.9804082
Total
25353.64456
5
3
15
23
P-value
1.283E-05
5.798E-10
F crit
2.9012945
3.2873821
APPENDIX B
Varian Analysis Calculation (ANOVA)
115
Table B12: Result of ANOVA for ferum in horizontal SSF
Time
Control
Vegetated
Vegetated
with
magnet
(%)
(Days)
(%)
(%)
3
6
9
12
15
18
56.79
59.26
81.48
86.42
87.65
92.59
56.79
65.43
86.42
86.42
90.12
96.30
66.67
77.78
90.12
92.59
100.00
100.00
4
4
4
4
4
4
Sum
183.2469136
208.4691358
267.0246914
277.4320988
292.7777778
306.8888889
Average
45.8117284
52.11728395
66.75617284
69.35802469
73.19444444
76.72222222
Variance
836.2742849
1004.518976
1495.098854
1470.664431
1533.603554
1541.722451
6
6
6
6
63
464.1975309
481.4814815
527.1604938
10.5
77.36625514
80.24691358
87.8600823
31.5
237.5654118
240.2072855
174.6176904
df
MS
603.7676485
7748.344652
26.70757972
F
22.60660287
290.1178142
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
ANOVA
Source of
Variation
Rows
Columns
Error
Total
Count
SS
3018.838242
23245.03396
400.6136958
26664.4859
5
3
15
23
P-value
1.713E-06
1.678E-13
F crit
2.9012945
3.2873821
APPENDIX B
Varian Analysis Calculation (ANOVA)
116
Table B13: Result of ANOVA for manganese in vertical SSF
Time
Control
Vegetated
(Days)
(%)
(%)
3
6
9
12
15
18
32.5
40
55
60
72.5
77.5
32.5
42.5
62.5
67.5
77.5
87.5
Vegetated
with
magnet
(%)
37.5
52.5
67.5
72.5
82.5
92.5
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
4
4
4
4
4
4
Sum
105.5
141
194
212
247.5
275.5
Average
26.375
35.25
48.5
53
61.875
68.875
Variance
248.3958333
409.4166667
719.8333333
773.5
993.2291667
1189.229167
6
6
6
6
63
337.5
370
405
10.5
56.25
61.66666667
67.5
31.5
311.875
434.1666667
400
df
MS
1022.385417
4075.010417
51.71875
F
19.76817724
78.7917422
ANOVA
Source of Variation
Rows
Columns
Error
SS
5111.927083
12225.03125
775.78125
Total
18112.73958
5
3
15
23
P-value
4.045E-06
2.076E-09
F crit
2.9012945
3.2873821
APPENDIX B
Varian Analysis Calculation (ANOVA)
117
Table B14: Result of ANOVA for manganese in horizontal SSF
Time
Control
Vegetated
(Days)
(%)
(%)
3
6
9
12
15
18
17.5
25.0
27.5
50.0
52.5
75.0
20.0
27.5
35.0
52.5
62.5
82.5
Vegetated
with
magnet
(%)
37.5
42.5
50.0
60.0
75.0
87.5
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Column 3
Column 4
Count
4
4
4
4
4
4
Sum
78
101
121.5
174.5
205
263
Average
19.5
25.25
30.375
43.625
51.25
65.75
Variance
200.1666667
224.4166667
290.5625
462.5625
668.75
1039.75
6
6
6
6
63
247.5
280
352.5
10.5
41.25
46.66666667
58.75
31.5
471.875
556.6666667
376.875
df
MS
1224.166667
2531.625
70.91666667
F
17.26204465
35.69858989
ANOVA
Source of Variation
Rows
Columns
Error
SS
6120.833333
7594.875
1063.75
Total
14779.45833
5
3
15
23
P-value
9.464E-06
4.532E-07
F crit
2.9012945
3.2873821
118
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B15: Result of ANOVA for TSS in vertical and horizontal SSF
Time
(Days)
3
6
9
12
15
18
Control
(%)
v
3.98
9.10
14.67
19.02
33.02
43.89
Control
(%)
h
5.84
9.92
18.07
28.94
40.22
46.33
Vegetated
(%)
v
9.65
14.54
23.51
31.79
36.41
47.69
Vegetated
(%)
h
14.67
19.02
28.53
37.77
44.70
48.37
Vegetated
with magnet
(%), v
29.35
46.10
72.69
75.04
82.57
90.04
Vegetated
with magnet
(%), h
31.39
44.02
64.81
72.55
83.22
86.40
P-value
9.42023E-05
0.031349628
F crit
5.050329058
6.607890969
Anova: Two Factor Without Replication for control vertical and horizontal SSF
SUMMARY
Count
Sum
Average
Variance
Row 1
2
9.82337
4.911684783
1.732429259
Row 2
2
19.02174
9.510869565
0.332289698
Row 3
2
32.74457
16.37228261
5.76891836
Row 4
2
47.96196
23.98097826
49.18810551
Row 5
2
73.2337
36.61684783
25.92782668
Row 6
2
90.21739
45.10869565
2.990607278
Column 1
Column 2
6
6
ANOVA
Source of
Variation
Rows
Columns
Error
SS
2455.74278
54.7780951
31.1620817
Total
2541.68296
123.6821
149.3207
20.61367754
24.88677536
228.4743042
268.9066684
df
MS
491.1485563
54.77809509
6.232416337
F
78.80547924
8.789222692
5
1
5
11
Anova: Two-Factor Without Replication for vegetated vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
24.32065
33.55978
52.03804
69.56522
81.11413
96.05978
Average
12.16032609
16.7798913
26.01902174
34.7826087
40.55706522
48.0298913
Variance
12.63623878
10.05176335
12.63623878
17.86980151
34.34583235
0.230756734
6
6
163.587
193.0707
27.26449275
32.17844203
201.5792376
188.6107091
119
APPENDIX B
Varian Analysis Calculation (ANOVA)
ANOVA
Source of
Variation
Rows
Columns
Error
SS
1935.61979
72.4406924
15.3299391
df
5
1
5
MS
387.1239588
72.44069244
3.065987811
F
126.2640241
23.62719518
P-value
2.94828E-05
0.004629988
F crit
5.050329058
6.607890969
Total
2023.39043
11
Anova: Two-Factor Without Replication for vegetated with magnet vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
60.7337
90.12228
137.5
147.5951
165.788
176.4402
Average
30.36684783
45.0611413
68.75
73.79755435
82.89402174
88.2201087
Variance
2.07681061
2.160713758
31.05062618
3.091124911
0.212665406
6.629548677
6
6
395.788
382.3913
65.96467391
63.73188406
543.6623494
481.472388
df
MS
1019.08165
14.95605161
6.053087587
F
168.3573276
2.470813679
ANOVA
Source of
Variation
Rows
Columns
Error
SS
5095.40825
14.9560516
30.2654379
Total
5140.62974
5
1
5
11
P-value
1.44622E-05
0.17678234
F crit
5.050329058
6.607890969
120
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B16: Result of ANOVA for Turbidity in vertical and horizontal SSF
Time
(Days)
3
6
9
12
15
18
Control
(%)
v
38.33
41.67
43.33
47.50
54.17
60.00
Control
(%)
h
37.50
44.17
50.83
54.17
56.67
61.67
Vegetated
(%)
v
45.00
47.50
53.33
61.67
63.33
64.17
Vegetated
(%)
h
48.33
52.50
57.50
59.17
60.83
65.00
Vegetated
with magnet
(%), v
25.00
47.50
55.83
61.67
77.50
89.17
Vegetated
with magnet
(%), h
19.17
46.67
59.17
70.83
81.67
86.67
P-value
0.001172006
0.049313088
F crit
5.050329058
6.607890969
Anova: Two Factor Without Replication for control vertical and horizontal SSF
SUMMARY
Count
Sum
Average
Variance
Row 1
2
75.83333 37.91666667 0.347222222
Row 2
2
85.83333 42.91666667
3.125
Row 3
2
94.16667 47.08333333
28.125
Row 4
2
101.6667 50.83333333 22.22222222
Row 5
2
110.8333 55.41666667
3.125
Row 6
2
121.6667 60.83333333 1.388888889
Column 1
Column 2
6
6
ANOVA
Source of
Variation
Rows
Columns
Error
SS
695.833333
33.3333333
25
Total
754.166667
285
305
47.5
50.83333333
67.22222222
76.94444444
5
1
5
MS
139.1666667
33.33333333
5
F
27.83333333
6.666666667
df
11
Anova: Two-Factor Without Replication for vegetated vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
93.33333
100
110.8333
120.8333
124.1667
129.1667
Average
46.66666667
50
55.41666667
60.41666667
62.08333333
64.58333333
Variance
5.555555556
12.5
8.680555556
3.125
3.125
0.347222222
6
6
335
343.3333
55.83333333
57.22222222
70.55555556
35.74074074
121
APPENDIX B
Varian Analysis Calculation (ANOVA)
ANOVA
Source of
Variation
Rows
Columns
Error
SS
503.935185
5.78703704
27.5462963
df
5
1
5
MS
100.787037
5.787037037
5.509259259
F
18.29411765
1.050420168
P-value
0.003139664
0.352413195
F crit
5.050329058
6.607890969
Total
537.268519
11
Anova: Two-Factor Without Replication for vegetated with magnet vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
44.16667
94.16667
115
132.5
159.1667
175.8333
Average
22.08333333
47.08333333
57.5
66.25
79.58333333
87.91666667
Variance
17.01388889
0.347222222
5.555555556
42.01388889
8.680555556
3.125
6
6
356.6667
364.1667
59.44444444
60.69444444
511.2962963
628.1712963
df
MS
1125.05787
4.6875
14.40972222
F
78.07630522
0.325301205
ANOVA
Source of
Variation
Rows
Columns
Error
SS
5625.28935
4.6875
72.0486111
Total
5702.02546
5
1
5
11
P-value
9.63769E-05
0.593112413
F crit
5.050329058
6.607890969
122
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B17: Result of ANOVA for ammonia nitrogen for vertical and horizontal SSF
Time
(Days)
3
6
9
12
15
18
Control
(%)
v
8.46
37.79
45.74
79.22
79.63
86.75
Control
(%)
h
9.85
45.74
51.91
67.54
72.68
79.38
Vegetated
(%)
v
32.79
34.12
59.41
90.36
91.54
94.11
Vegetated
(%)
h
9.26
47.65
66.21
75.04
79.38
80.37
Vegetated
with magnet
(%), v
26.65
33.38
49.85
84.26
88.48
93.91
Vegetated
with magnet
(%), h
19.63
48.68
56.40
65.00
71.10
76.32
P-value
0.000316347
0.617418401
F crit
5.050329058
6.607890969
Anova: Two Factor Without Replication for control vertical and horizontal SSF
SUMMARY
Count
Sum
Average
Variance
Row 1
2
18.30882 9.154411765 0.975886678
Row 2
2
83.52941 41.76470588 31.53114187
Row 3
2
97.64706 48.82352941 19.07439446
Row 4
2
146.7574 73.37867647 68.25586613
Row 5
2
152.3162 76.15808824 24.14103049
Row 6
2
166.125
83.0625
27.1953125
Column 1
Column 2
6
6
ANOVA
Source of
Variation
Rows
Columns
Error
SS
7774.34004
9.17463686
161.998995
Total
7945.51367
337.5882
327.0956
56.26470588
54.51593137
948.017474
639.2503334
df
MS
1554.868008
9.174636858
32.39979906
F
47.99005098
0.28316956
5
1
5
11
Anova: Two-Factor Without Replication for vegetated vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
42.05882
81.76471
125.625
165.3971
170.9191
174.4779
Average
21.02941176
40.88235294
62.8125
82.69852941
85.45955882
87.23897059
Variance
276.816609
91.52249135
23.13000108
117.4052768
74.04371215
94.43017409
6
6
402.3382
357.9044
67.05637255
59.65073529
838.3877739
756.1747135
123
APPENDIX B
Varian Analysis Calculation (ANOVA)
ANOVA
Source of
Variation
Rows
Columns
Error
SS
7459.99456
164.530389
512.817875
df
5
1
5
MS
1491.998912
164.5303895
102.563575
F
14.54706422
1.604179549
P-value
0.005312177
0.261107281
F crit
5.050329058
6.607890969
Total
8137.34283
11
Anova: Two-Factor Without Replication for vegetated with magnet vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
46.28676
82.05882
106.25
149.2647
159.5809
170.2353
Average
23.14338235
41.02941176
53.125
74.63235294
79.79044118
85.11764706
Variance
24.65465506
116.9550173
21.41273789
185.5644464
150.9453125
154.6730104
6
6
376.5441
337.1324
62.75735294
56.18872549
885.5098183
419.6656935
df
MS
1200.222596
129.4405998
104.9529159
F
11.43581943
1.233320662
ANOVA
Source of
Variation
Rows
Columns
Error
SS
6001.11298
129.4406
524.76458
Total
6655.31816
5
1
5
11
P-value
0.009116571
0.317293606
F crit
5.050329058
6.607890969
124
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B18: Result of ANOVA for nitrate in vertical and horizontal SSF
Time
(Days)
3
6
9
12
15
18
Control
(%)
v
43.40
55.47
43.40
65.28
66.04
66.04
Control
(%)
h
31.32
20.75
35.09
55.47
69.06
66.42
Vegetated
(%)
v
48.68
57.74
49.06
69.81
81.89
69.81
Vegetated
(%)
h
43.02
30.94
50.19
61.51
78.87
81.89
Vegetated
with magnet
(%), v
51.70
58.87
49.43
77.36
84.15
69.81
Vegetated
with magnet
(%), h
41.13
34.72
57.74
63.02
84.91
87.92
P-value
0.054265462
0.119344994
F crit
5.050329058
6.607890969
Anova: Two Factor Without Replication for control vertical and horizontal SSF
SUMMARY
Count
Sum
Average
Variance
Row 1
2
74.71698 37.35849057 72.90850837
Row 2
2
76.22642 38.11320755 602.6343895
Row 3
2
78.49057 39.24528302 34.46066216
Row 4
2
120.7547 60.37735849 48.13100748
Row 5
2
135.0943 67.54716981 4.556781773
Row 6
2
132.4528 66.22641509 0.071199715
Column 1
Column 2
6
6
ANOVA
Source of
Variation
Rows
Columns
Error
SS
2165.10027
315.284206
447.478343
Total
2927.86282
339.6226
278.1132
56.60377358
46.35220126
120.6977572
401.8179661
df
MS
433.0200546
315.2842055
89.49566868
F
4.838447055
3.522899043
5
1
5
11
Anova: Two-Factor Without Replication for vegetated vertical and horizontal SSF
SUMMARY
Count
Sum
Average
Variance
Row 1
2
91.69811
45.8490566 16.01993592
Row 2
2
88.67925 44.33962264 358.9177643
Row 3
2
99.24528 49.62264151 0.640797437
Row 4
2
131.3208 65.66037736 34.46066216
Row 5
2
160.7547 80.37735849 4.556781773
Row 6
2
151.6981
75.8490566 72.90850837
Column 1
Column 2
6
6
376.9811
346.4151
62.83018868
57.73584906
175.3079388
407.0914916
125
APPENDIX B
Varian Analysis Calculation (ANOVA)
ANOVA
Source of
Variation
Rows
Columns
Error
SS
2502.34959
77.8568886
409.647561
df
5
1
5
MS
500.4699181
77.85688857
81.92951228
F
6.108542626
0.950291127
P-value
0.034414509
0.374416253
F crit
5.050329058
6.607890969
Total
2989.85404
11
Anova: Two-Factor Without Replication for vegetated with magnet vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
92.83019
93.58491
107.1698
140.3774
169.0566
157.7358
Average
46.41509434
46.79245283
53.58490566
70.18867925
84.52830189
78.86792453
Variance
55.82057672
291.6340335
34.46066216
102.8123888
0.284798861
164.0441438
6
6
391.3208
369.434
65.22012579
61.57232704
199.838614
478.9414976
df
MS
556.9526522
39.91930699
121.8274594
F
4.571651212
0.327670849
ANOVA
Source of
Variation
Rows
Columns
Error
SS
2784.76326
39.919307
609.137297
Total
3433.81986
5
1
5
11
P-value
0.060391481
0.591810226
F crit
5.050329058
6.607890969
126
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B19: Result of ANOVA for P in vertical and horizontal SSF
Time
(Days)
3
6
9
12
15
18
Control
(%)
v
10.61
14.77
19.89
28.41
30.87
52.27
Control
(%)
h
21.40
25.00
38.45
28.79
35.23
50.19
Vegetated
(%)
v
20.45
28.03
30.87
37.50
43.56
61.93
Vegetated
(%)
h
30.30
29.92
53.98
43.94
54.73
55.49
Vegetated
with magnet
(%), v
55.49
47.73
71.78
78.03
81.63
90.91
Vegetated
with magnet
(%), h
50.76
61.74
74.24
72.54
74.24
88.64
P-value
0.011188099
0.073623963
F crit
5.050329058
6.607890969
Anova: Two Factor Without Replication for control vertical and horizontal SSF
SUMMARY
Count
Sum
Average
Variance
Row 1
2
32.00758 16.00378788 58.27091942
Row 2
2
39.77273 19.88636364 52.29855372
Row 3
2
58.33333 29.16666667 172.2480487
Row 4
2
57.19697 28.59848485 0.071740129
Row 5
2
66.09848 33.04924242 9.487632002
Row 6
2
102.4621 51.23106061 2.170138889
Column 1
Column 2
6
6
ANOVA
Source of
Variation
Rows
Columns
Error
SS
1520.36762
148.648536
145.898497
Total
1814.91465
156.8182
199.053
26.13636364
33.17550505
224.0157254
109.2374981
df
MS
304.0735241
148.6485355
29.17969946
F
10.42072159
5.094244914
5
1
5
11
Anova: Two-Factor Without Replication for vegetated vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
50.75758
57.95455
84.84848
81.43939
98.29061
117.42
Average
25.37878788
28.97727273
42.42424242
40.71969697
49.14530303
58.71
Variance
48.49632691
1.793503214
266.9450184
20.73289715
62.37768049
20.7368
6
6
222.3467
268.3639
37.05777778
44.72732323
211.3091986
145.852516
127
APPENDIX B
Varian Analysis Calculation (ANOVA)
ANOVA
Source of
Variation
Rows
Columns
Error
SS
1541.19213
176.465782
244.616444
df
5
1
5
MS
308.2384258
176.4657824
48.92328874
F
6.30044369
3.60698937
P-value
0.032338482
0.115981188
F crit
5.050329058
6.607890969
Total
1962.27436
11
Anova: Two-Factor Without Replication for vegetated with magnet vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
106.25
109.4697
146.0227
150.5682
155.8712
179.5455
Average
53.125
54.73484848
73.01136364
75.28409091
77.93560606
89.77272727
Variance
11.20939509
98.212236
3.031020432
15.08336203
27.27918388
2.582644628
6
6
425.5682
422.1591
70.9280303
70.35984848
268.2901458
165.4865416
df
MS
402.4908173
0.968491736
31.28587006
F
12.86493923
0.030956203
ANOVA
Source of
Variation
Rows
Columns
Error
SS
2012.45409
0.96849174
156.42935
Total
2169.85193
5
1
5
11
P-value
0.007011171
0.867242071
F crit
5.050329058
6.607890969
128
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B20: Result of ANOVA for ferum in vertical and horizontal SSF
Time
(Days)
3
6
9
12
15
18
Control
(%)
v
32.10
46.54
66.67
79.01
88.89
90.12
Control
(%)
h
56.79
59.26
81.48
86.42
87.65
92.59
Vegetated
(%)
v
45.68
65.43
70.37
86.42
92.59
96.30
Vegetated
(%)
h
56.79
65.43
86.42
86.42
90.12
96.30
Vegetated
with magnet
(%), v
53.09
70.37
71.60
85.19
98.77
100.00
Vegetated
with magnet
(%), h
66.67
77.78
90.12
92.59
100.00
100.00
P-value
0.003586301
0.044822773
F crit
5.050329058
6.607890969
Anova: Two Factor Without Replication for control vertical and horizontal SSF
SUMMARY
Count
Sum
Average
Variance
Row 1
2
88.88889 44.44444444 304.8315806
Row 2
2
105.8025 52.90123457 80.84895595
Row 3
2
148.1481 74.07407407
109.739369
Row 4
2
165.4321 82.71604938 27.43484225
Row 5
2
176.5432 88.27160494 0.762078951
Row 6
2
182.716 91.35802469 3.048315806
Column 1
Column 2
6
6
ANOVA
Source of
Variation
Rows
Columns
Error
SS
3764.37154
308.704212
217.960931
Total
4291.03668
403.3333
464.1975
67.22222222
77.36625514
558.9010822
237.5654118
df
MS
752.8743078
308.7042118
43.59218615
F
17.27085458
7.081640978
5
1
5
11
Anova: Two-Factor Without Replication for vegetated vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
102.4691
130.8642
156.7901
172.8395
182.716
192.5926
Average
51.2345679
65.43209877
78.39506173
86.41975309
91.35802469
96.2962963
Variance
61.72839506
0
128.7913428
0
3.048315806
0
6
6
456.7901
481.4815
76.13168724
80.24691358
371.6913072
240.2072855
129
APPENDIX B
Varian Analysis Calculation (ANOVA)
ANOVA
Source of
Variation
Rows
Columns
Error
SS
2916.73017
50.8052634
142.76279
df
5
1
5
MS
583.3460346
50.80526343
28.55255805
F
20.43060498
1.779359431
P-value
0.002428551
0.23975834
F crit
5.050329058
6.607890969
Total
3110.29823
11
Anova: Two-Factor Without Replication for vegetated with magnet vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
119.7531
148.1481
161.7284
177.7778
198.7654
200
Average
59.87654321
74.07407407
80.86419753
88.88888889
99.38271605
100
Variance
92.21155312
27.43484225
171.4677641
27.43484225
0.762078951
0
6
6
479.0123
527.1605
79.83539095
87.8600823
333.2825281
174.6176904
df
MS
482.6754052
193.1870142
25.22481329
F
19.13494461
7.658610272
ANOVA
Source of
Variation
Rows
Columns
Error
SS
2413.37703
193.187014
126.124066
Total
2732.68811
5
1
5
11
P-value
0.002828867
0.039485851
F crit
5.050329058
6.607890969
130
APPENDIX B
Varian Analysis Calculation (ANOVA)
Table B21: Result of ANOVA for manganese in vertical and horizontal SSF
Time
(Days)
3
6
9
12
15
18
Control
(%)
v
32.5
40.0
55.0
60.0
72.5
77.5
Control
(%)
h
17.5
25.0
27.5
50.0
52.5
75.0
Vegetated
(%)
v
32.5
42.5
62.5
67.5
77.5
87.5
Vegetated
(%)
h
20.0
27.5
35.0
52.5
62.5
82.5
Vegetated
with magnet
(%), v
37.5
52.5
67.5
72.5
82.5
92.5
Vegetated
with magnet
(%), h
37.5
42.5
50.0
60.0
75.0
87.5
Anova: Two Factor Without Replication for control vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Count
Column 1
Column 2
ANOVA
Source of Variation
Rows
Columns
Error
Total
2
2
2
2
2
2
Sum
50
65
82.5
110
125
152.5
Average
25
32.5
41.25
55
62.5
76.25
Variance
112.5
112.5
378.125
50
200
3.125
6
6
337.5
247.5
56.25
41.25
311.875
471.875
MS
747.5
675
36.25
F
20.62068966
18.62068966
SS
3737.5
675
181.25
4593.75
df
5
1
5
P-value
0.002376602
0.007605297
11
Anova: Two-Factor Without Replication for vegetated vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
52.5
70
97.5
120
140
170
Average
26.25
35
48.75
60
70
85
Variance
78.125
112.5
378.125
112.5
112.5
12.5
6
6
370
280
61.66666667
46.66666667
434.1666667
556.6666667
F crit
5.050329058
6.607890969
131
APPENDIX B
Varian Analysis Calculation (ANOVA)
ANOVA
Source of Variation
Rows
Columns
Error
SS
4822.91667
675
131.25
Total
5629.16667
df
5
1
5
MS
964.5833333
675
26.25
F
36.74603175
25.71428571
P-value
0.000603087
0.00386403
F crit
5.050329058
6.607890969
11
Anova: Two-Factor Without Replication for vegetated with magnet vertical and horizontal SSF
SUMMARY
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Column 1
Column 2
Count
2
2
2
2
2
2
Sum
75
95
117.5
132.5
157.5
180
Average
37.5
47.5
58.75
66.25
78.75
90
6
6
405
352.5
67.5
58.75
400
376.875
MS
758.4375
229.6875
18.4375
F
41.13559322
12.45762712
ANOVA
Source of Variation
Rows
Columns
Error
SS
3792.1875
229.6875
92.1875
Total
4114.0625
df
5
1
5
11
Variance
0
50
153.125
78.125
28.125
12.5
P-value
0.000459454
0.016748032
F crit
5.050329058
6.607890969