LANDFILL LEACHATE TREATMENT USING FREE WATER SURFACE
CONSTRUCTED WETLANDS
SITI RABE’AH BINTI OTHMAN
A project report submitted in partial fulfillment of the
requirements for the award of the degree of
Master of Engineering (Civil – Environmental Management)
Faculty of Civil Engineering
Universiti Teknologi Malaysia
NOVEMBER, 2007
iii
This work is dedicated to my parents Hj. Othman Hj. Kassim,
Hjh. Laila Mariam Hj. Pudzil and my family members who love
me and support me during my whole journey of education.
Without you all who am I today!
iv
ACKNOWLEDGEMENT
“In the name of God, the most gracious, the most compassionate”
I would like to thank and express my appreciation for the support that I
received throughout my studies from my supervisor, Assoc. Prof. Dr. Johan Sohaili
and Pn. Normala Hashim and Cik Shamila Azman. They went above and beyond the
call of my duty as members of my steering committee, and never failed to keep my
eyes on the bottom line.
I enjoyed doing my M.Eng study under their supervision. Also, during my
stay at Universiti Teknologi Malaysia I have had the chance to meet and learn from
many people. Among them there are three individuals that have been a great teacher
and friend, and have contributed to my studies by discussing and commenting on
different aspects of this work. Special thanks go to Dr. Fadhil Othman, Dr. Fadhil
Md. Din, and Dr. Azmi Aris as well.
Many friends and colleagues have contributed to my studies in many ways.
The exceptional help, support and friendship that I received from Mohd. Izuddin,
Mohd. Fahmi, Hafizi, Abd. Karim and Azhan.
Finally, I wish to express my heartfelt thanks to all my environmental
laboratories technicians, especially to Pak Usop, En. Ramlee Ismail, Pn. Rosmawati
and En. Muzaffar 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
ABSTRAK
Masa kini, pengurusan sisa pepejal dan rawatan airsisa merupakan masalah utama
yang sedang kita hadapi. Jumlah sisa pepejal yang dihasilkan di seluruh dunia
meningkat secara mendadak, begitu juga di Malaysia amnya. Walaupun terdapat
pelbagai alternatif untuk mengurangkannya, atau untuk tujuan rawatan dan
pelupusan. Tempat pelupusan sampah (landfill) masih kerap dipraktikkan di negara
maju dan membangun. Walaubagaimanapun, kaedah landfill ini menyebabkan
penghasilan air leleh (leachate). Air leleh (leachate) dari pusat pelupusan sampah
adalah merupakan cecair yang menyusup dari sesuatu tapak pelupusan ke alam
sekitar. Tanah bencah buatan (constructed wetlands) muncul sebagai salah satu
kaedah rawatan alternatif yang berpotensi dengan menggunakan tumbuhan
tenggelam (emergent plant) untuk menyingkirkan bahan cemar dari air leleh. Dalam
kajian ini, tanah bencah buatan telah di bangunkan menggunakan tumbuhan
Limnocharis flava untuk merawat air leleh dari tapak pelupusan. Kepekatan air leleh
yang berbeza (50% dan 33%) telah dikaji di tanah bencah buatan tersebut untuk
membandingkan keupayaan rawatan dari segi keupayaan penyingkiran bahan cemar
dan keupayaan penyingkiran tanah bencah buatan apabila masa tahanan hidraulik
(HRT) yang berlainan digunakan. Keputusan menunjukkan bahawa keupayaan
penyingkiran tertinggi bagi HRT 3 hari telah diperolehi di Cell B dimana peratus
penyingkiran NH3-N, PO43-, Mn, Fe, Turbidity, dan TSS adalah 83%, 88%, 91%,
92%, 100%, dan 98%. Bagi HRT 6 hari pula, penyingkiran tertinggi adalah NO3-N,
PO43-, Turbidity dan TSS dimana peratusan adalah 98%, 98%, 100% dan 90% telah
didapati di Cell B, selain itu, penyingkiran tertinggi bagi Cell A pula berlaku di HRT
6 hari dimana parameter yang diperolehi adalah NH3-N, COD, Mn, Fe, Tubidity dan
TSS iaitu 93%, 91%, 90%, 94%, 100% dan 90%. Walaubagaimanapun, keputusan
makmal menunjukkan bahawa keupayaan penyingkiran bagi HRT 3 hari dan 6 hari
tidak menunjukkan perbezaan yang ketara.
vi
ABSTRACT
Nowadays, solid waste management and wastewater treatment are the most
important problems that we are facing. The amount of solid waste produced around
the world is increasing at high rate as well as in Malaysia. Although there are
different alternatives to reduce them or for their treatment and disposition, landfill is
still the most common practice in developed and developing countries. However, the
landfill method causes generation of leachate Landfill leachate refers to the liquid
that seeps through a landfill site and enters the environment. Constructed wetlands
emerged as one of the potential treatment alternative that employed emergent plants
to remove pollutant from leachate. In this research, a constructed wetland was
developed by using Limnocharis flava to treat the landfill leachate. Different leachate
concentration (50% and 33%) was studied in the constructed wetland to compare the
treatment efficiency in terms of pollutants removal in leachate and the efficiency of
the system in different hydraulic retention time (HRT). The result shows a better
removal efficiencies at HRT 3 days can be obtained in Cell B where the parameter
are NH3-N, PO43-, Mn, Fe, Turbidity, and TSS (83%, 88%, 91%, 92%, 100%, and
98% removal). The highest removal at HRT 6 days are NO3-N, PO43-, Turbidity and
TSS (98%, 98%, 100% and 90%) can be obtained in Cell B, while in Cell A the
highest removal parameters are NH3-N, COD, Mn, Fe, Tubidity and TSS (93%, 91%,
90%, 94%, 100% and 90%). However, the highest removal of COD can be obtained
at HRT 6 days in control unit of 94%. However, the laboratory result shows that the
removal efficiencies for HRT 3 days and HRT 9 days have not much different.
vii
TABLE OF CONTENT
CHAPTER
1
2
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRAK
v
ABSTRACT
vi
TABLE OF CONTENTS
vii
LIST OF FIGURES
x
LIST OF PLATES
xiii
LIST OF TABLES
xiv
LIST OF SYMBOLS
xvi
LIST OF APPENDICES
xvii
INTRODUCTION
1
1.1
Reviews
1
1.2
Constructed Wetland and Landfill
2
1.3
Objectives of the Study
4
1.4
Scope of Study
5
1.5
Problem Statement
5
LITERATURE REVIEW
7
2.1
Introduction
7
2.2
What is Constructed Wetlands?
8
2.3
Types of Constructed Wetland
9
2.3.1 Free Water Surface Wetlands (FWS)
10
viii
2.3.2 Sub-Surface Flow Wetlands (SSF)
12
2.3.3 Hybrid Systems
17
2.4
Theory of Operation
18
2.5
Aquatic Macrophytes
19
2.6
Treatment Process Mechanisme
22
2.6.1 Biodegradable Organic Matter Removal
22
2.6.2
Metal Removal Mechanisms
26
2.6.3
Removal of Nitrogen
26
2.6.4
Removal of Phosphorus
29
2.7
3
2.6.5 Solids Removal
31
Landfill Leachate
31
2.7.1
Leachate Generation
32
2.7.2
Leachate Composition
33
2.8
Leachate Contol Strategies
36
2.9
Type of Landfill
37
RESEARCH METHODOLOGY
39
3.1
Introduction
39
3.2
Experimental Set Up and Operating Conditions of
41
Constructed Wetland
3.3
4
Experimental Analysis
44
3.3.1 Analysis of Leachate
44
RESULTS AND DISCUSSION
47
4.1
Introduction
47
4.2
Pollutant Removal In Leachate
48
4.3
Water Quality Analysis
51
4.3.1 Total Suspended Solid Removal
52
4.3.2 Turbidity Removal
54
Organic Matter Analysis
56
4.4.1
56
4.4
4.5
Biochemical Oxygen Demand Removal
Chemical Water Quality Analysis
58
4.5.1
58
Ammonia Nitrogen Removal
ix
5
4.5.2 Nitrate Nitrogen Removal
59
4.5.3
Phosphorus Removal
61
4.5.4
Manganese Removal
63
4.5.5 Iron Removal
65
4.6
Analysis of Variance
66
4.7
Conclusion
67
CONCLUSIONS
69
5.1
Introduction
69
5.2
Recommendations
70
5.3
Conclusions
71
REFERENCES
73
APPENDICES
84
x
LIST OF FIGURES
NO.
TITLE
PAGE
Figure 2.1
Typical surface flow and subsurface flow constructed wetlands
9
Figure 2.2
Classification of constructed wetlands for wastewater treatment
10
(Vymazal, 2001)
Figure 2.3
Free water surface flow (FWS) constructed wetland
12
Figure 2.4
The free water surface constructed wetlands in a foreign
12
country
Figure 2.5
The subsurface constructed wetlands in a foreign country
13
Figure 2.6
Longitudinal constructed wetlands with horizontal SSF. Key:
15
1)
Inflow
of
mechanically
pretreated
wastewater;
2)
Distribution zone filled with large stone; 3) Impermeable liner;
4) Medium (Gravel, sand, crush stones); 5) Vegetation; 6)
Outlet collector; 7) Collection zones filled with large stones; 8)
Water level in the bed maintained with outlet structure; 9)
outflow (Vymazal, 1997).
Figure 2.7
Typical arrangement of a vertical flow (VF) reed bed system
16
Figure 2.8
Hybrid constructed wetlands for wastewater treatment (based
18
on Cooper, 1999)
Figure 2.9
Floating aquatic weeds (a) water lettuce (Pista stratiotes); (b)
20
water lily (Nymphaeaceae)
Figure 2.10
Emergent aquatic weeds (a) Cattails (Typha latifolia); (b)
21
common reeds (Phragmites australis)
Figure 2.11
Aerobic condition (oxygen from water column if FWS systems
and from atmosphere if SF systems) (Chongrak and Lim, 1998)
23
xi
Figure 2.12
Aerobic condition (oxygen from plant roots) (Chongrak and
23
Lim, 1998)
Figure 2.13
Simplified wetlands nitrogen cycle (Kadlec and Knight, 1996)
29
Figure 2.14
Phosphorus removal process in constructed wetlands
30
Figure 2.15
Typical layout of landfill
32
Figure 2.16
Classification of landfill structures (Chew, 2005)
38
Figure 3.1
The framework of study
40
Figure 3.2
Limnocharis flava (yellow burhead)
42
Figure 4.1
Percentage of removal for Cell A and B for total suspended
53
solids (TSS). The FWSCW system can reach until 100%
removal for both cells.
Figure 4.2
Concentration of TSS as a function of sampling day for Cell A,
54
B as well as control unit where the concentration at HRT 9 day
reaches 0 mg/l. It was believed that all the particles are trapped
in the media.
Figure 4.3
Percentage removal for Cell A, B and control unit in different
54
HRT. The percentage removals are increasing steadily where
the system can reach until 100% removal for those cells in
FWSCW.
Figure 4.4
The turbidity concentration with different HRT for Cell A, B
55
and control unit where the leachate concentration are decrease
due to sedimentation and filtration that occur during the
process.
Figure 4.5
The percentage of removal of COD for Cell A, B and control
56
unit. The removals are increase steadily up to 94% removal in
control unit. On the other hand, the removal of control unit
higher than Cell A and B which was probably due to the
presence of non-biodegradable organic compounds in the
landfill leachate.
Figure 4.6
The effluent quality for Cell A, B and control unit with
different HRT. The highest COD removal occurs in Cell B at
HRT 9 day with 95.0 mg/l. The effluent quality for HRT 3 day
can be observed in Cell A with 93.0 mg/l.
57
xii
Figure 4.7
The percentage of removal for NH3-N with different hydraulic
58
retention time (HRT). The highest removal can be obtained in
Cell A at HRT 6 day. The lowest removal of NH3-N occurs in
control unit with 26% at HRT 6 day.
Figure 4.8
The percentage of removal for NO3-N with different hydraulic
60
retention time (HRT). The highest removal can be obtained in
Cell B at HRT 6 day with removal 98%. The lowest removal of
NO3-N occurs in control unit with 25% at HRT 9 day.
Figure 4.9
The percentage removal of orthophosphate under different
62
HRT. The highest removal can be obtained in Cell B at HRT 6
day with removal 98%. The lowest removal of PO43- occurs in
control unit with 23% at HRT 3 day.
Figure 4.10
The percentage removal of manganese under different HRT.
64
The highest removal can be obtained in Cell B at HRT 3 day
with removal 91%. The lowest removal of Mn occurs in control
unit with 48% at HRT 9 day.
Figure 4.11
The percentage removal of iron (Fe) under different HRT. The
highest removal can be obtained in Cell A at HRT 6 days with
removal 94%. The lowest removal of Mn occurs in control unit
with 17% at HRT 3 days.
65
xiii
LIST OF PLATES
NO.
TITLE
PAGE
Plate 3.1
Lab-scale constructed wetland
41
Plate 3.2
Dilution of landfill leachate before pour into the cells
43
Plate 3.3
Different concentration during the experiment
44
xiv
LIST OF TABLES
NO.
TITLE
Table 2.1
Some environmental requirements of the aquatic weeds
PAGE
24
(adapted from Stephenson et. al., 1980; Reed et. al., 1988
and USEPA, 1988).
Table 2.2
Summary of removal mechanisms in wetland for the
25
pollutant in wastewater (Adapted from Stowell et. al., 1981)
Table 2.3
Nitrogen transformation in wetlands
Table 2.4
Landfill leachate composition from three different sources
34
(Harrington et al., 1986)
Table 2.5
Landfill Leachate Composition from new and mature
35
landfill (Tchobanoglous et. al., 1993).
Table 2.6
Landfill Aged Influence on BOD5/COD Ratio and pH of
36
leachate (Henry, 1987 and Amokrane, 1997)
Table 2.7
Classification of Landfill Structure (Pankratz, 2001)
37
Table 3.1
The characteristics of the Limnocharis flava
43
Table 4.1
Characteristics of landfill leachate used in FWSCW
48
experiments
Table 4.2
Effluent concentration after treated by FWSCW for Cell A
49
Table 4.3
Effluent concentration after treated by FWSCW for Cell B
49
Table 4.4
Effluent concentration after treated by FWSCW for control
50
unit
Table 4.5
Removal efficiencies in FWSCW at HRT 3 day
50
Table 4.6
Removal efficiencies in FWSCW at HRT 6 day
51
Table 4.7
Removal efficiencies in FWSCW at HRT 9 day
51
Table 4.8
Significant differences between control, Cell A and Cell B
66
at HRT 3 days
xv
Table 4.9
Significant differences between control, Cell A and Cell B
67
at HRT 6 days
Table 4.10
Significant differences between control, Cell A and Cell B
67
at HRT 9 days
Table 4.11
Percentage removal for three cells at HRT 6 days
68
xvi
LIST OF SYMBOLS
Ca
Calcium
CW
Constructed wetlands
Fe
Ferum
FWS
Free water surface
FWSCW
Free water surface constructed wetland
HRT
Hydraulic retention time
mg/l
milligram per litre
N2
dinitrogen
N2O
Nitrous oxide
NO3-
Nitrate
NO2-
Nirite
NO2
Nitric oxide
NH4
Ammonium
Mg
Magnesium
Mn
Manganese
NH3
Ammonia
ppm
Part per million
SSF
Sub-surface flow
SSFCW
Sub-surface flow constructed wetlands
TSS
Total suspended solid
Zn
Zinc
VF
Vertical Flow
xvii
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
Appendix A
Standard B Under Environmental Quality (Sewage
85
and Industrial Effluent) Regulations 1979
Appendix B
Laboratory Analyses
86
Appendix C
Analysis of Variance
96
Appendix D
Figures Of The Whole Experiment
120
CHAPTER 1
INTRODUCTION
1.1
Reviews
Over the last years, the high population growth rate, industrialization and
urbanization, have been the causes for several environment all over the world.
Nowadays, solid waste management and wastewater treatment are the most
important problems that we are facing. The amount of solid waste produced around
the world is increasing at high rate as well as in Malaysia. Kuala Lumpur and
Selangor produced 7922 tonnes/day in year 2000, and this will increase to 11 728
tonnes/day in year 2010. For the states of Negeri Sembilan, Melaka and Johor, waste
generated for 2000 for 2633 tonnes/day and 3539 tonnes/day are expected by year
2015 (Maseri, 2005). Although there are different alternatives to reduce them or for
their treatment and disposition, landfill is still the most common practice in
developed and developing countries.
However, the landfill method causes generation of leachate (Galbrand, 2003).
According to Pankratz (2001), leachate can be defined as any contaminated liquid
that is generated from water percolation through a solid waste disposal site,
accumulating contaminants and moving into subsurface areas. As these wastes are
compacted or chemically react, bound water is release as leachate. Landfill leachate
2
refers to the liquid that seeps through a landfill site and enters the environment. This
liquid may already be in the material dumped into the landfill, or it may be the result
of rainwater entering the landfill, filtering through the waste material and picking up
additional chemicals before leaking out into the environment. Landfill leachate that
escapes from the environment is most likely to eventually mix with the groundwater
near the site. The quantity of these leachates is small as compared to others
wastewater, but their contents are extremely hazardous (Tizaoui, at el., 2006).
Landfills are potential threats to groundwater quality (Howard, 1997), the
primary concern being the production and treatment of leachate (Eyles and Boyce,
1997). Major environmental problems have arisen from the production and migration
of leachates from landfill sites and subsequent contamination of surrounding land
and water (McBean et al., 1995). To prevent the adverse impacts of landfill leachate
on aquatic life and degradation of water quality, landfill leachate has to be collected
and treated before final discharge into the environment (Sartaj, 2001).
Conventional treatment systems are costly and require a long-term
commitment. Moreover, the great variations in strength and flows of leachate as well
as its toxic effect, due to presence of high concentrations of heavy metals and/or
organic substances, make the use of these systems undesireable (Vesilind et al.,
2002; Tchbanoglous et al., 1993). Many landfill operators are now considering nonconventional systems such as engineered constructed wetlands, which are low
energy, do not require chemicals, and can satisfactorily address the leachate
management problems (Sartaj, 2002). However, the modern landfill sites require that
the landfill leachate to be collected and treated. Since there is no method to ensure
that rainwater cannot enter the landfill site, landfill sites must now have an
impermeable layer at the bottom.
1.2
Constructed Wetland and Landfill
The role of wetlands in water resource management is fact gaining ground
resulting in the construction wetlands in most developed countries. Constructed
3
wetlands are man-made system that involves altering the existing terrain to simulate
wetlands conditions. They primarily attempt to replicate the treatment that has been
observed to occur when polluted water enters the natural wetlands (Chew, 2006).
Constructed wetlands have been used as an attractive low-cost method for
controlling water pollution from both point and nonpoint sources (Olson, 1992;
Mitsch, 1992). Dundabin and Bowmer (1992) have revealed that constructed wetland
also show good potential for concentrating metals from industrial wastewaters.
Wetlands prevent the contamination of groundwater or to prevent groundwater from
infiltrating into the wetland (Kadlec et al., 2000). As reported by Olson (1992),
constructed and natural wetlands also can contribute in reducing heavy metal and
nutrient significantly to watershed water quality. On the other hand, constructed
wetlands are also used to improve or restore some water bodies such as rivers and
water basins (Nairn and Mitsch, 2000; Mitsch et al., 2005 and Mitsch and Day,
2006).
Among the aquatic treatment systems, constructed wetlands have a greater
potential in wastewater treatment because they can tolerate higher organic loading
rate and shorter hydraulic retention time with improved effluent characteristics
(Chongrak and Lim, 1998).
The treatment of industrial and domestic wastewaters by passage through
beds containing plants of the common reed (Phragmites australis), reedmace (Typha
latifolia), or other species, has been widely practised in recent years, with varying
degrees of success (Barr and Robinson, 1999). This has often been shown to limit the
value of reed beds for treatment of raw landfill leachates. Engineered wetlands do
however; have considerable capability for secondary polishing of leachates that have
been pretreated in aerobic biological plants and for older leachates (Barr and
Robinson, 1999).
There are two types of constructed wetlands: free water surface (FWS)
wetlands also known as surface flow wetlands) and subsurface flow (SSF) wetlands
(also known as root zone method wetlands or rock-filters) (Liehr et. al., 2000). FWS
4
systems consist of several basins or cells with the water surface being 0.12 – 2.0
metres above the substrate (Tousignant et. al., 1999).
However, both surface-flow and subsurface-flow constructed wetlands have
been identified as promising technologies for the treatment of landfill leachate
(Kadlec and Knight, 1996). Constructed wetlands have a small ecological footprint,
utilize “low-tech” technology, and have an aesthetic value similar to that of natural
wetlands. The application of wetland technology for treating landfill leachate is still
developing (Nivala, et al., 2006). Wetland also was categorized in the Best
Management Practices (BMP) which is one of the best to reduce non-point
source
pollution (Ayob and Supiah, 2005).
1.3
Objectives of the Study
The aim of this study was to establish a diverse, self-sustaining, locally-
modelled, native vegetation community bearing biological integrity treatment
wetland site that effectively decontaminate the leachate input via phytoremediative,
physiochemical and biophysical means. The hypothesis of this study is that “the
selected native vegetation and vegetation establishment strategy will yield a
successfully established site bearing biological integrity and that a naturalized system
supporting biological integrity will effectively remediate the characterized
contaminated leachate input”.
The purpose of this project was to evaluate the efficiency in the context of
treating real landfill leachate on-site using a laboratory scale system. The more
specific goals of the study are given below:
a) To investigate the feasibility of applying free water surface constructed
wetland system to treat landfill leachate containing high organic matters and
nutrient, under different concentration of leachate;
5
b) To determine the relationship between removal efficiency and different
hydraulic retention time (HRT).
1.4
Scope of Study
This study comprises of a series of laboratory scale experiment. Leachate from a
municipal solid waste landfill will be used. This study will cover:
a) A laboratory scale wetland which will be developed for the treatment of
leachate;
b) Each system contained 2 cells. Each cells were planted with same number of
plant 40 no. to 80 no. of plant.
c) The efficiency of landfill leachate treatment system is analysed in terms of
ammonia nitrogen (NH3-N), nitrate nitrogen (NO3--N), orthophosphates
(PO43-), COD, manganese (Mn), and iron (Fe). HACH DR/4000
spectrophotometer equipment was used for analysis of each particular
parameter;
d) The vegetation species that was used in this study is Limnocharis flava;
e) All experiments were carried out in Environmental Engineering Laboratory,
Faculty of Civil Engineering, Universiti Teknologi Malaysia.
1.5
Problem Statement
As cities are growing in size with a rise in the population, the amount of
waste generated is increasing becoming unmanageable. The local corporations have
adapted different methods for the disposal of waste such as open dumps, landfills,
6
sanitary landfills, as well as incineration plants. Besides, landfilling methods will
generate a leachate and it will contaminate the groundwater table. These leachates
may migrate from the refuse and contaminate surface and ground waters, which may
affect human health and the aquatic environment. Treatment of these leachates in
classical wastewater treatment plants is rarely practiced due to the nature and high
levels of pollutants present in them (i.e. high COD, low biodegradability, heavy
metals, pathogens, etc.). Dedicated treatment facilities are therefore required before
the leachate being discharged to the environment or to the sewer system. As an
alterative, constructed wetlands are suitable for treating leachate from landfill sites
which can be very harmful if not treated properly. 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. Also, bearing in mind that landfilled
wastes may take up to a hundred years to stabilize.
CHAPTER 2
LITERATURE REVIEW
2.1
Introduction
Constructed wetlands treat a wide variety of wastewaters and runoff waters
using emergent plants. Free water surface (FWS), subsurface flow (SSF), and
vertical flow (VF) constructed wetland all use a combination of fixed-film biological
activity and physical, chemical, or photochemical mechanisms. The treatment of
landfill leachate is one particular application for which constructed wetlands have
been used widely (Crites, 2005).
The characteristics and flow of landfill leachates depend of the composition
of solid wastes, precipitation, runoff, age of the landfill and permeability and type of
cover. Solid waste composition varies substantially with socio-economic conditions,
location, season, waste collection and disposal methods, sampling and sorting
procedures and many others factors (El-Fadel et al., 1997). In addition to the leachate
generation induced by precipitation, it is also produced as a result of biochemical
processes that convert solid materials to liquid forms.
8
2.2
What is Constructed Wetlands?
Natural wetlands are called by other names such as bogs, swamps, and
marshes. Bogs occur at higher elevations and are described as spongy, with poorly
drained soil. Swamps are characterized by the presence of trees, while marshes have
a lot of sedges and grasses with trees growing on the edges of the wetland. Nivala et
al (2006) have revealed that constructed wetlands have a small ecological footprint,
utilize “low tech” technology, and have an aesthetic value similar to that of natural
wetlands. In Malaysia, we have one man-made wetlands called Putrajaya Wetland.
Constructed wetlands are engineered systems that have been designed and
constructed to utilize the natural processes involving wetland vegetation, soils, and
their associated microbial assemblages to assist in treating wastewater (Vymazal, J.,
2006). Constructed wetland technology is more widespread in industrialized
countries due to more stringent discharge standards, finance availability, change in
tendency to use on-site technologies instead of centralized systems, and the existing
pool of experience and knowledge based on science and practical works (Korkusuz
et. al., 2005).
Constructed wetlands are becoming increasingly common features emerging
in landscapes across the globe. Although similar in appearance to natural wetland
systems (especially marsh ecosystems), they are usually created in areas that would
not naturally support such systems to facilitate contaminant or pollution removal
from wastewater or runoff (Hammer, 1992; and Mitsch and Gosselink, 2000).
According to Lim et. al. (2003), the constructed wetlands have higher tendency o
remove pollutants such as organic matters, suspended solids, heavy metal and other
pollutants simultaneously. Some of the studies show that the ability of wetland
systems to effectively reduce total suspended solid, biochemical oxygen demand
(Watson et al., 1990 and Rousseau, 2005), and fecal coliform (Nokes et. al., 1999
and Nerall et. al., 2000) are well established. Nitrogen (ammonia and total nitrogen)
and phosphorus are processed with relatively low efficiency by most wetland
systems (Steer et al., 2005).
9
Fields (1993) stated that constructed wetlands are built specifically for water
quality improvement purposes, typically involving controlled outflow and a design
that maximizes certain treatment functions. In addition to this, wetlands are usually
utilized as secondary and even tertiary treatment because of toxic effects on the
aquatic plants due to high organic loading of the influents (Solano et. al., 2004).
2.3
Types of Constructed Wetland
There are several types of constructed wetlands; surface flow wetlands,
subsurface flow wetlands, and hybrid systems that incorporate surface and
subsurface flow wetlands. Constructed wetland systems can also be combined with
conventional treatment technologies (Davis, 1995) The basic classification is based
on the type of macrophytic growth, further classification usually based on the water
flow regime (Vymazal, J. 2006) as illustrate in Figure 2.2.
Figure 2.1 shows the typical surface flow (SF) and subsurface flow (SSF)
constructed wetlands. Constructed wetland design include horizontal surface and
sub-surface flow wetlands are similar to natural marshes as they tend to occupy
shallow channels and basins through which water flows at low velocities above and
within the substrate. The basins normally contain a combination of gravel, clay- or
peat-based soils and crushed rock, planted with macrophytes (Shutes, 2001).
(Source: Water pollution control federation, 1990)
Figure 2.1: Typical surface flow and subsurface flow constructed wetlands
10
Constructed
wetlands
Free floating
plants
Floating
leaves plants
Emergent
plants
Surface flow
(Free water surface)
Downflow
Submerged
plants
Subsurface
flow
Vertical flow
Horizontal flow
Upflow
Hybrid systems
Figure 2.2: Classification of constructed wetlands for wastewater
treatment (Vymazal, 2001)
2.3.1
Free Water Surface Wetlands (FWS)
Free water surface (FWS) wetlands are treatment wetlands in which the
surface water flowing through them is exposed to the atmosphere. They typically
consist of several basins or cells with the water surface being 0.15 to 2.0 metres
above the substrate (Tousignant et al., 1999). The near surface layer is aerobic while
the deeper waters and substrate are usually anaerobic (Galbrand, 2003 and Chew,
2006). As reported by Vymazal et. al. (2006), in free water surface wetlands, oxygen
is mainly supplied to the wetland through algal photosynthesis and atmospheric
diffusion.
The FWS wetlands technology started with the ecological engineering of
natural wetlands wastewater treatment. Constructed FWS treatment wetlands mimic
the hydrological regime of natural wetlands (Noor, 2006). In surface flow (SF)
wetlands, water flows over the soil surface from an inlet point to an outlet point or, in
11
a few cases, is totally lost to evaporation and infiltration within the wetlands (Chew,
2006 and Nazaitulshila, 2006). As stated by Lim et al. (1998), the FWS system
consist of basins or channels and barriers such as constructed clay layer or
geotechnical material to prevent seepage. Figure 2.3 shows the free water surface
constructed wetland.
These systems are primarily constructed to treat municipal wastewater, mine
drainage, urban storm water, agricultural runoff and livestock wastes, and landfill
leachate (USEPA, 2000). Figure 2.4 shows the free water surface constructed
wetlands in a foreign country.
Free water surface wetlands are sometimes called surface flow wetlands. The
advantages of surface flow wetlands are that their capital and operating costs are low,
and their construction, operation, and maintenance are straightforward (Davis, 1995).
An addition to, Galbrand (2003) has revealed that there are a few more advantage of
using FWS such as (a) significant reduction
in the levels of nitrogen and
phosphorus, metals, persistent organic and fecal coliforms, (b) superiority in their
abilities to remove biochemical oxygen demand (BOD), chemical oxygen demand
(COD), and total suspended solids (TSS).
The main disadvantage of surface flow systems are (a) require a large land
area than other systems (Davis, 1995; and Galbrand, 2003), (b) wastewater are
exposed and are therefore accessible to humans and animals, hence it may not prove
prudent to establish these wetlands in high use area such as parks, playgrounds, or
similar public facilities, (c) pollutants such as phosphorus, metals and some
persistent organics can become bound in wetland sediments and accumulate over
time (USEPA, 2000 ; Davis, 1995; and Liehr et al., 2000). Moreover, this system
will contribute to the odour problem and as attraction of unwanted pests such as
mosquitoes that breed easily in the water.
12
Figure 2.3: Free water surface flow (FWS) constructed wetland
(Source: Earthpace Resources)
Figure 2.4: The free water surface constructed wetlands in a foreign
2.3.2
Sub-Surface Flow Wetlands (SSF)
Many of the earliest treatment wetlands in Europe were subsurface flow
(SSF) systems constructed to treat mechanically pretreated municipal wastewater as
shown in Figure 2.5. Moreover, the subsurface flow constructed wetlands first
emerged as a wastewater treatment technology in Western Europe based on research
13
by Seidel commencing in the 1960s, and by Kickuth in the late 1970s and early
1980s as reported by Sherwood (1993). Soil and gravel-based SSF wetlands are still
the most prevalent application of this technology in Europe. SSF wetlands that use
gravel substrates have also been used extensively in the United States. According to
Liehr et al. (2000), a SSF system consists of a sealed basin with a porous substrate of
rock, grave or coarse sand planted with emergent macrophytes such as reeds,
Eurasian watermilfoil and duckweeds. This technology is generally limited to
systems with low flow rates and can be used with less than secondary pretreatment.
Subsurface flow wetlands differ from FWS wetlands in that they incorporate
a rock or gravel matrix that the wastewater is passed through in a horizontal or
vertical fashion (DeBusk et.al, 2001). Unless the matrix clogs, the top layer of the
bed in horizontal flow systems will remain dry. The SSF configuration offers several
advantages, including a decreased likelihood of odour production and no insect
proliferation within the wetlands as long as surface ponding is avoided. Unlike FWS
wetlands, SSF systems provide no aesthetic or recreational benefits and few, if any,
benefits to wildlife.
(Source: USGS)
Figure 2.5: The subsurface constructed wetlands in a foreign country.
Subsurface flow wetlands continue to provide effective treatment of most
wastewater constituents through the winter in temperature climates. The subsurface
microbial treatment processes still function, albeit at a reduced rate, even when the
14
surface vegetation has senesced or died, and the matrix surface is covered with snow
and ice. Subsurface flow wetlands also can be operated in a vertical flow fashion
which can reduce matrix clogging problems and enhance certain contaminant
removal processes such as nitrification.
Because of the high cost of the gravel or rock matrix, SSF wetlands never
attain the large spatial footprint of the large FWS wetlands. Concerns over matrix
clogging and the potential high cost of renovation also limit the deployment of
extremely large SSF wetlands. However, SSF are finding increased use for small
applications, such as for small communities or single family homes. The limitations
of septic systems for nutrient control have become more apparent in the past two
decades (Hagedorn et.al., 1981), and SSF wetlands are one technology that is being
deployed to improve nutrient removal performance (Mitchell et.al., 1990).
Subsurface flow systems are the only wetlands configuration suitable for this
purpose, because they crate no standing water, thereby limiting the likelihood of
human exposure to wastewater pathogens (House et.al., 1999).
a)
Horizontal-flow systems (HF)
The system is called horizontal flow because the wastewater enters the inlet
and flows slowly through the porous medium under the surface of bed in an ore or
less horizontal way until it flows out through the outlet. As the wastewater flows
from the inlet to the outlet, it comes into contact with three zones, which are aerobic
zones, anaerobic zones and anoxic zones. These zones are categorized as biological
treatment methods (Uygur and Kargi, 2004). Aerobic zones are found in the area
where there are presence of oxygen such as around the roots and rhizomes. As the
wastewater passes through this zone, it is cleaned by microbiological degradation
and by physical and chemical process (Cooper et al., 1990).
Organic compound are degraded aerobically and anaerobically by the bacteria
that are attached to the roots and rhizomes. Components such as nitrogen is removed
by the major process which are nitrification and denitrification and also other
processes such as volatilization, adsorption and plant uptake. Ammonia is oxidized to
nitrate by nitrifying bacteria in aerobic zones and nitrates are converted to nitrogen
15
gaseous by nitrifying bacteria in anoxic zones (Cooper et al., 1990). As for
phosphorus removal, it occurred through ligand exchange reactions. Phosphates
replace water or hydroxyl ions from the surface of Fe and Al hydrous oxides.
The media, which is used in horizontal sub-surface flow constructed wetlands
like gravel and crushed stones do not contain high quantities of Fe, Al or Ca, so the
removal of phosphorus is rather low. Figure 2.6 shows a typical arrangement for the
subsurface constructed wetland with horizontal flow (HF).
Figure 2.6: Longitudinal constructed wetlands with horizontal SSF. Key: 1) Inflow
of mechanically pretreated wastewater; 2) Distribution zone filled with large stone;
3) Impermeable liner; 4) Medium (Gravel, sand, crush stones); 5) Vegetation; 6)
Outlet collector; 7) Collection zones filled with large stones; 8) Water level in the
bed maintained with outlet structure; 9) outflow (Vymazal, 1997).
b)
Vertical Flow Systems
Vertical-flow (VF) treatment wetlands are frequently planted with common
reed. Other emergent wetlands plants such as cattail or bulrush can also be used. VF
reed beds typical look like the system show in Figure 2.7. They are composed of a
flat bed of gravel topped with sand, with reed growing at the same sort of densities as
horizontal-flow (HF) systems (Chew, 2006). They are fed intermittently. The liquid
is dosed on the bed in a large batch, flooding the surface. The liquid then gradually
drains vertically down through the bed and is collected by a drainage network at the
base. The bed drains completely free, allowing air to refill the bed. The next dose of
16
liquid trap air this together with the aeration caused by the rapid dosing on the bed
leads to good oxygen transfer and hence the ability to decompose BOD and to nitrify
ammonia nitrogen.
Figure 2.7: Typical arrangement of a vertical flow (VF) reed bed system
As with the horizontal flow (HF) systems, the reeds in vertical flow (VF)
systems will transfer some oxygen down into the rhizosphere, but it will be small in
comparison with the oxygen transfer created by the dosing system. Vertical flow
(VF) treatment wetlands are very similar in principle to a rustic biological filter.
They are less good at the removal of suspended solid and in most cases will be
followed by a horizontal flow bed as part of a multistage treatment wetlands system.
The advantages cited for sub-surface flow (SSF) wetlands are greater cold
tolerance, minimization of pest and odor problems, and possibly, greater assimilation
potential per unit of land area than in surface flow (SF) systems. It has been claimed
that the porous medium provides greater surface area for treatment contact than is
found in surface flow (SF) wetlands, so that the treatment responses should be faster
for sub-surface flow (SSF) wetlands which can, therefore, be smaller than a surface
flow (SF) system designed for the same volume of wastewater. Since the water
surface is not exposed, public access problems are minimal. Several subsurface
systems are operating in parks, with public access encouraged.
17
The disadvantages of sub-surface flow (SSF) wetlands are that they are more
expensive to construct, on a unit basis than surface flow (SF) wetlands. Because of
cost, subsurface wetlands are often used for small flows. Sub-surface flow (SSF)
wetlands may be more difficult to regulate than surface flow (SF) wetlands, and
maintenance and repair costs are generally higher than for surface wetlands. A
number of systems have had problems with clogging and unintended surface flows.
2.3.3
Hybrid Systems
Various types of constructed wetlands may be combined in order to achieve
higher treatment effect, especially for nitrogen (Vymazal, 2005). Single stage
systems require than all of the removal processes occur in the same space. In hybrid
or multistage systems, different cells are designed for different types of reactions.
Effective wetland treatment of mine drainage may require a sequence of different
wetland cells to promote aerobic and anaerobic reactions as may the removal of
ammonia from agricultural wastewater. However, hybrid systems comprise most
frequently VSSF (VF) and HSSF (HF) systems arranged in a stage manner as shown
in Figure 2.8. However, there are been a growing interest in achieving fully nitrified
effluents (Vymazal, 2006). Vymazal (2005) revealed that there are now many fine
examples of HF systems for secondary treatment and they proved very satisfactory
where the standard required only BOD5 and SS removal.
However, there has been a growing interest in achieving fully nitrified
effluents. HF systems cannot do this because of their limited oxygen transfer
capacity. Moreover, Vymazal (2005) add that VF systems, on the other hand do
provide a good conditions for nitrification but no denitrification occurs in these
systems. In combined systems (hybrid system), the advantages of HF and VF
systems can be combined to complement each other. A research done by Cooper
(1999, 2001), it is possible to produce an effluent low in BOD, which is fully
nitrified and partly denitrified and hence has a much lower total-N concentrations.
18
Figure 2.8: Hybrid constructed wetlands for wastewater treatment (Cooper, 1999)
2.4
Theory of Operation
The deliberate uses of wetlands (both natural and constructed) as biological
treatment systems for effluent purification have developed rapidly over the last 25-30
years (Brix, 1993). Theoretically, wastewater flows through the root zone, which the
plants supply with oxygen and channels for wastewater flow. The efficiency and cost
effectiveness of this method of treatment are highly controversial. Although many
sites are in operation, the tremendous variation in site design, soil type, loading rate,
and wastewater characteristics have made comparison difficult. Further studies are
needed to evaluate optimal loading regimes and the specific area needed for
maximum performance efficiency (Forsburg, 1996).
Several types of natural wetlands, such as southern swamps, bottomland
hardwood forests, freshwater marshes, northern bogs, and brackish and saltwater
marshes have been used for the improvement of water quality for centuries. Because
of their transitional position between terrestrial and aquatic ecosystem, some
wetlands have been subjected to both municipal and industrial wastewater
19
discharges. Wetland has also received agricultural runoff, combined sewer overflow,
stormwater runoff, mine drainage, and other sources of water pollution (Bastian et
al., 1989). In early 1980’s there were over 500 natural wastewater treatment wetlands
in operation in U.S (U.S EPA, 1983).
There are still too few data from natural wetland leachate system to allow
indisputable predictions of the treatment performance and the effects of leachate
discharge on the receiving ecosystems. Exploiting this technology without adequate
evaluation could to unfortunate results. Also, using natural wetlands for wastewater
treatment has several advantages (Forsburg, 1996).
Wetland systems are effective in reducing many contaminants (e.g., nitrogen,
phosphorus, trace organic compounds, metals, and pathogens) (Wildeman and
Laudon, 1989). The pollutants in these systems are removed through a combination
of physical, chemical, and biological processes. Low-cost immobilization of
pollutants for long periods of time is the goal of using constructed wetlands for water
pollution treatment. As reported by Kadlec and Knight (1996), some possible metal
removal mechanisms associated with municipal solid waste (MSW) landfill leachate
include bioaccumulation in plants, adsorption in sediments, precipitation as insoluble
salts, incorporation by a range of organic materials such as algae, detritus and
bacteria.
Bioaccumulation and adsorption have been reported to have finite capacities
to retain metals and, if dominant in controlling metal retention, may indicate poor
long-term treatment performance. But metal removal in constructed wetland systems
has received little attention to date because most existing systems treat wastewaters
having low concentrations of heavy metals.
2.5
Aquatic Macrophytes
Thousands of plants have adapted to life in water or wetlands, with a
significant proportion of them occurring only in wetlands and shallow water. Many
20
wetlands are readily identified by vegetation and traditional methods relied on plants
for wetland identification and delineation. Plants also serve as a basis for wetland
classification. Rooted emergent aquatic macrophytes, such as common reeds
(Phragmites australis), cattails (Typha latifolia) and bulrushes (Scirpus lacustris),
are the dominant plants in wetlands (Mitsch and Gosselink, 1993). These species
produce aerial stems and leaves, and an extensive root and rhizome system
(Forsburg, 1996). According to Cronk and Fennessy (2001), the emergent plants are
rooted in the soil where their leaves and stems which are the photosynthetic parts of
the plants are called aerial.
Plants growing in wetlands and water are technically called hydrophytes.
Most wetland plants do not grow strictly in water or very wet soils, but also grow in
terrestrial habitats, especially under mesic soil conditions. Many of these species are
more common on the latter sites, but have populations that tolerate varying degrees
of soil wetness. Unfortunately, due to lack of distinctive morphological differences,
individuals of these wetland populations can only be recognized as hydrophytes
when associated with more typical hydrophytic species or after identification of
hydric soils (i.e., periodically anaerobic soils due to excessive wetness) and other
reliable signs of wetland hydrology at a given location. The categories used to group
wetland plants include emergent, submerged, floating-leaved, and floating. The
general characteristics of each group are described in next sub-section.
The major types of aquatic macrophytes are submerged, floating and
emergent weeds; some of these are shown in Figure 2.9 and 2.10, respectively.
(a)
(b)
Figure 2.9: Floating aquatic weeds (a) water lettuce (Pistia stratiotes); (b) water lily
(Nymphaeaceae)
21
(a)
(b)
Figure 2.10: Emergent aquatic weeds: (a) Cattails (Typha latifolia);
(b) Common reeds (Phragmites australis)
Submerged plants are either suspended in the water column or rooted in the
bottom sediments. In submerged species, all photosynthetic tissues are normally
underwater (Cook, 1996). These species are not effective for wastewater treatment
due to the requirement of light penetration into the water bodies. The second types of
aquatic weeds, namely the floating type, have their root portions submerged but not
attached to the soil. According to Galbrand (2003), there are two sub-types of
floating weeds, i.e floating unattached weeds where their roots are hanging free in
the water and are not anchored in the sediments whereas the floating attached weed,
their leaves are floating on the water surface while their roots are anchored in the
substrate.
Emergent plants are rooted in the soil with basal portions that typically grow
beneath the surface of the water, but whose leaves, stems (photosynthetic parts), and
reproductive organs are aerial. These plants tend to have a higher potential in
wastewater treatment because they can serve as a microbial habitat and as a filtering
medium (Chongrak and Lim, 1998). Cattails (Typha spp.) and reeds (Phragmites
app.) are easy to propagate and produce a large biomass. They thrive under a wide
range of water quality and other environmental conditions, including acidic waters
with iron concentrations of up to 100 mg/l. The rhizospheres of Typha and
Phragmites app. provide an effective matrix which traps and filters sediment
particles and associated metals. Moreover, bulrushes (Scirpus spp.) are also easy to
22
propagate, produce a large biomass, and can thrive under a wide range of water
quality and environmental conditions. They are reported to be more susceptible to
transplanting stress than cattails and have a slower rate of spread.
The floating-leaved plants are also known as floating attached (Cronk and
Fennessy, 2001). The plant leaves float on the water’s surface while their roots are
anchored in the substrates. Floating-leaved species shade the water column below
and are often able to outcompete submerged species for light, particularly when
turbidity levels are high and light penetration is reduced (Haslam, 1978). Example of
floating-leaved plants is Nymphaeaceae or better known as water lily as shown in
previous Figure 2.9.
However, the pathway of metal transfer from the sediment and interstitial
water to the roots and rhizomes is still not fully understood and requires further
investigation. The common types of aquatic weeds, their scientific names and some
of the environmental requirements are given in Table 2.1.
2.6
Treatment Process Mechanisme
An understanding of the treatment mechanisms is essential so that the design
of wetland systems can be improved for better treatment performance. The principal
pollutant removal mechanisms operatives in wetland systems are listed in Table 2.2
and they include sedimentation, chemical precipitation, and adsorption, microbial
metabolic activity and plant uptake (Chongrak and Lim, 1998).
2.6.1
Biodegradable Organic Matter Removal
In wetland systems, microbial degradation plays a dominant role in the
removal of soluble/colloidal biodegradable organic matter (BOD or COD) in
wastewater, the remaining BOD associated with settleable solids being removed by
23
sedimentation. Both the SF and FWS systems essentially function as attached growth
biological reactors. For the FWS systems, however, the contribution of suspended
microbial growth in the water column to BOD removal cannot be neglected. The
mechanism of BOD removal in the attached biofilm is similar to that of trickling
filters (Chongrak and Lim, 1998).
Biodegradation takes place when dissolved organics is carried by the
diffusion process into the biofilms on the submerged plant stems (FWS systems), the
root system and surrounding soil or media (Chongrak and Lim, 1998). The role of
wetland vegetations is confined to providing a support medium for microbial
degradation to take place as in Figure 2.11, and to conveying oxygen to the
rhizosphere for aerobic biodegradation to occur in Figure 2.12.
Figure 2.11: Aerobic condition (oxygen from water column if FWS
systems and from atmosphere if SF systems) (Chongrak and Lim, 1998)
Figure 2.12: Aerobic condition (oxygen from plant roots)
(Chongrak and Lim, 1998)
Water hyacinth,
Eichhornia crassipes
Water fern
Azolla app.
Duckwed,
Lemna spp.
Cattails,
Typha spp.
Common reed,
Phrgmites communis
Rushes,
Juncus spp.
Bulrushes,
Scirpus spp.
Sedges,
Carex spp.
Floating
Note:
5
5
12-24
10-30
-
>10
20-30
10-30
12-33
12-26
16-27
14-32
Worldwide
Worldwide
Worldwide
Worldwide
Worldwide
Worldwide
-
10-25++
Temperate region
10
-
15-25++
Worldwide
20-30
23-26++
18-26++
Worldwide
Tropical and subtropical region
Worldwide
Survival*
Desirable
Distribution
Ambient temperature
*Temperature range for seed germination; roots and rhizomes can survive in frozen soils.
+ppt = parts per thousand
++Water temperature (only for submerged types)
Pondweed
Potamogeton spp.
Eurasian watermillfoil,
Myriophyllum spacitum
Coontail,
Ceratophyllum demersum
Submerged
Emergent
Common name, scientific
name
Types of aquatic
weeds
12-100
-30-150
-10-10
-75-200
5-95
2.5
16.6
7
30
45
20
20
-
-
-
Water
level, cm
pH
5-7.5
4-9
5-7.5
2-8
4-10
4.5-7.5
3.5-11
5.9-7.0
7.1-8.7
5.0-10
6.3-10
Optimum
3.8
10
15
Maximu
m salinity
tolerance,
ppt
Table 2.1: Some environmental requirements of the aquatic weeds
(Adapted from Stephenson et. al., 1980; Reed et. al., 1988 and USEPA, 1988).
24
P
I
Bacterial
& virus
Volatilization of NH3 from the wastewater
Interparticle attractive forces
(van der Waals force)
Particulates filtered mechanically as water
passes through substrate, and root masses
Gravitational settling of solids (and
constituent pollutants) in wetland settings.
Description
S
P
S
S
S
S
P
P
P
S
Natural decay of organisms in an
unfavourable environment
Under proper conditions, significant
quantities of these pollutants will be taken up
by plants.
Uptake and metabolism of organics by
plants. Root excretion may be toxic to
organism of enteric origin
Decomposition of alteration of less stable
compounds by phenomena such as UV
irradiation, oxidation, and reduction
Removal of colloidal solids and soluble
organics by suspended, benthic, and plantspported bacteria. Bacterial
nitrification/denitrification.
Notes:
a
P = primary effects; S = secondary effect; I = incidental effect (effect occurring incidental to removal of another pollutant)
b
The term metabolism includes both biosynthesis and catabolic reactions.
Natural die-off
Plant Adsortion
Plant Metabolism
Biological bacteria
metabolismb
Decomposition
Adsorption on substrate and plant surfaces
S
I
Refractory
organics
P
I
Heavy
metals
P
I
P
Adsorption
S
I
N
Formation of or co-precipitation with
insoluble compounds
P
I
BOD
P
P
S
S
S
Colloidal
solids
P
S
P
Settleable
solids
Chemical Precipitation
Volatilization
Adsorption
Filtration
Physical Sedimentation
Mechanisms
Pollutant affecteda
Table 2.2: Summary of removal mechanisms in wetland for the pollutant in wastewater (Adapted from Stowell et. al., 1981)
25
26
2.6.2
Metal Removal Mechanisms
The potential for uptake by vegetation appears to be a small and unimportant
source of metal removal in wetland systems (Dunbabin and Bowmer, 1992). A
preliminary iron mass balance for a constructed wetland receiving AMD emphasizes
the small role of vegetation and the dominant role of sediments in removing and
storing iron (Fennessy and Mitsch, 1992).
Forsburg (1996) reported that the current information suggests there are two
complementary processes for iron and manganese retention and degradation in
constructed wetlands: biologically mediated oxidation and reduction processes. The
anaerobic conditions found in wetlands enhance retention or metals. This coupled
with aerated conditions in the rhizosphere allow many processes to occur
simultaneously. Reduction processes as removal mechanisms, have not been fully
explored (Spratt et al., 1987). Questions remain concerning the exact mechanisms,
controlling factors, and long-term functional capabilities of these processes.
In an experiment to determine if metal uptake by vegetation represents a
major flux of metals out of the ecosystem, Shutes et al. (1993) concluded that the
significance of the uptake of metals in the plant tissue is negligible, as the amount of
metals taken up during a growing season constituted less than 3% of the total content
introduced with the wastewater. Forsburg (1996) suggested that the subsurface
introduction of effluent into CW would maximize the purification potential, and that
metals will become immobilized on the increased sediment – root surfaces.
2.6.3
Removal of Nitrogen
Nitrogen has a complex biogeochemical cycle with multiple biotic/abiotic
transformations involving seven valence states (+5 to -3). The compounds include a
variety of inorganic and organic nitrogen forms that are essential for all biological
life (Vymazal, 2006). The most important inorganic forms of nitrogen in wetlands
are ammonium (NH4+), nitrite (NO2-) and nitrate (NO3-). Gaseous nitrogen may exist
27
as dinitrogen (N2), nitrous oxide (N2O), nitric oxide (NO2 and N2O4) and ammonia
(NH3).
Removal of nitrogen in wetlands is achieved through three main mechanisms:
nitrification/denitrification, volatilization of ammonia and uptake by plants.
Chongrak and Lim (1998) reported that there is still no general consensus among the
researchers on the relative importance of the removal mechanisms specifically
between nitrification/denitrification and plant uptake.
(a)
Nitrogen Transformation in Wetlands
Mitsch and Gosselink (1986) define nitrogen mineralization as the biological
transformation of organically combined nitrogen to ammonium nitrogen during
organic matter degradation. This can be both an aerobic and anaerobic process and is
often referred to as ammonificaton. Mineralization of organically combined nitrogen
releases inorganic nitrogen as nitrates, nitrites, ammonia and ammonium, making it
available for plants, fungi and bacteria. Mineralization rates may be affected by
oxygen levels in a wetland.
Wetzel (1983) defines nitrification as the biological conversion of organic
and inorganic nitrogenous compounds from a reduced state to a more oxidized state.
Nitrification is strictly an aerobic process in which the end product is nitrate (NO3-)
this product is limited when anaerobic conditions prevail (Patrick and Reddy, 1976).
Nitrification will occur readily down to 0.3 ppm dissolved oxygen (Keeney, 1973).
The process of nitrification oxidizes ammonium (from the sediment) to nitrite
(NO2-), and then nitrite is oxidized to nitrate (NO3-). The overall nitrification
reactions are as follow (Davies and Hart, 1990):
2NH4+ + 3O2 ↔ 4H+ + 2H2O + 2NO2-
(1)
2NO2- + O2 ↔ 2NO3-
(2)
According to Wetzel (1983), denitrification by bacteria is the biochemical
reduction of oxidized nitrogen anions, nitrate-N and nitrite-N, with contaminant
28
oxidation of organic matter. The general sequence as given by Wetzel (1983) is as
follows:
NO3- → NO2- → N2O → N2
(3)
The end product, N2O and N2 are gases that re-enter the atmosphere.
Denitrification is most commonly defined as the process which nitrate is converted
into dinitrogen via intermediates nitrite, nitric oxide and nitrous oxide (Hauck, 1984;
Paul and Clark, 1996; Jetten et al., 1997). The nitrate can be removed either through
plant uptake as its main nitrogen nutrient or reduce through denitrification process
(Galbrand, 2003). Denitrification occurs intensely in anaerobic environments but will
also occur in aerobic conditions (Bandurski, 1965). As reported by Hammer and
Knight (1994), the denitrification process occurs in anaerobic environment and the
denitrifying bacteria are Pseudomonas, Achtomobacter, Aerobacter, Bacillus,
Proteus and Micrococcus.
Liehr et al. (200) stated that ammonification process can occur in both
aerobic and anaerobic condition. Ammonia volatilization is a physiochemical process
where ammonium-N is known to be in equilibrium between gaseous and hydroxyl
forms (Vymazal, 2006). According to Reddy and Patrick (1984), the losses of NH3
through volatilization from flooded soils and sediments are insignificant if the pH
value is below 8.0. At pH of 9.3 the ratio between ammonia and ammonium ions is
1:1 and the losses via volatilization are significant. Ammonification rates are
dependent on temperature, pH, C/N ratio, available nutrients and soil conditions such
as texture and structure (Reddy and Patrick, 1984). Vymazal (2006) revealed that
algal photosynthesis in wetlands as well as photosynthesis by submerged
macrophytes often creates high pH values during the day. The pH of shallow flood
water is greatly affected by the total respiration activity of all the heterotrophic
organisms and the gross photosynthesis of the sepsis present. The optimal
ammonification temperature is reported to be 40 - 60 ˚C while optimal pH is between
6.5 and 8.5 (Vymazal, 1995). Volatilization of ammonia can be result in nitrogen
removal rates as high as 2.2 g N m-2 d-1. Table 2.3 shows the nitrogen
transformations in constructed wetlands, while Figure 2.13 illustrates the simplified
nitrogen cycle in wetlands.
29
Table 2.3: Nitrogen transformations in constructed wetlands (Vymazal, 2006)
Process
Transformation
Volatilization
Ammonia-N (aq)
Ammonification
Organic-N
Nitrification
Ammonia-N
Nitrate-ammonification
Nitrate-N
Denitrification
Nitrate-N
N2, Fixation
Gaseous N2
Plant/microbial uptake (assimilation)
Ammonia-, nitrite-, nitrate-N
Ammonia adsorption
Ammonia-N
•
Organic nitrogen burial
•
ANAMMOX (anaerobic ammonia
ammonia-N (g)
ammonia-N
nitrite-N
nitrate-N
ammonia-N
nitrite-N
gaseous N2, N2O
ammonia-N (organic-N)
organic-N
gaseous N2
oxidation)
Figure 2.13: Simplified wetlands nitrogen cycle (Kadlec and Knight, 1996)
2.6.4 Removal of Phosphorus
Phosphorus in wetlands occurs as phosphate in organic and inorganic
compounds. Free orthophosphate is the only form of phosphorus believed to be
utilized directly by algae and macrophytes and thus represents a major link between
30
organic and inorganic phosphorus cycling in wetlands (Vymazal, 2006). Meanwhile,
according to Chongrak and Lim (1998), the phosphorus removal mechanism in
wetland systems include vegetative uptake, microbial assimilation, adsorption onto
soil (mainly clay) and organic matter and precipitation with Ca2+, Mg2+, Fe2+ and
Mn2+. Adsorption and precipitation reactions are the major removal pathways when
the hydraulic retention time is longer and finer-textured soils are being used, since
this allows greater opportunity for phosphorus sorption and soil reactions to occur
(Reed and Brown, 1992).
Similar to that of nitrogen removal, the relative importance of phosphorus
removal via plant uptake pathway is still a subject for debate. Nonetheless, it is the
only mechanism by which phosphorus is removed from the wetland systems.
Adsorption and precipitation reactions merely trap the phosphorus in the wetland
soil. Once the storage capacity has been exceeded, the soil/sediment has to be
dredged for ultimate disposal (Lim and Chongrak, 1998). Figure 2.14 depicted the
removal process of phosphorus in constructed wetlands.
Figure 2.14: Phosphorus removal process in constructed wetlands
31
2.6.5
Solids Removal
Settleable solids are removed easily via gravity sedimentation as wetland
systems generally have long hydraulic retention times. Nonsettling/colloidal solids
are removed via mechanisms which include: straining (if sand media is used);
sedimentation and biodegradation (as a result of bacterial growth); and collisions
(inertial and Brownian) with an adsorption (Van der Waals forces) of other solids
(plants, soil, sand and gravel media). For gravel media which forms an important
component in a subsurface flow wetland system, Sapkota and Bavor (1994)
suggested that the suspended solids removal is primarily by sedimentation and
biodegradation similar to what is occurring within a trickling filter.
On the other hand, the solid removal mechanism are very depends on the
sizes and nature of solids present in the wastewater, as well as the types of filter
media used. In all cases, wetland vegetation has a negligible role to play in solids
removal.
2.7
Landfill Leachate
Prior to 1965 very few people were aware of the fact that water passing
through solid waste in a sanitary landfill would become highly contaminated. This
water, termed leachate, was generally not a matter of concern until few cases of
water pollution were noted where leachate had caused harm (Boyle and Ham, 1974).
Boyle and Ham (1974) also reported that many contaminants released from sanitary
landfill, if allowed to migrate, may pose a severe threat to surface and ground water.
Kouzeli-Katsiri et al. (1999) also revealed that the production of leachate can
becomes harmful to all organisms if it moves out of landfill into the surrounding soil.
The composition and quantity of leachate is subject to seasonal and even
daily fluctuations, which significantly impact the design of leachate treatment plants.
Figure 2.15 depicted a typical layout of a landfill.
32
Figure 2.15: Typical layout of landfill
2.7.1
Leachate Generation
Organic and mineral compounds generated as products of waste
mineralization within biological processes and accompanying physical and chemical
processes are washed out by percolating rainwater through the deposit of wastes in
landfill and form heavy polluted waters, or leachate. Leachate generation
accompanies landfill during its exploitation and a long time after its closing and
recultivation. According to Lu et al. (1985), there are a number of factors that
contribute to leachate generation such as availability of water, landfill surface
condition, refuse condition and underlying of soil conditions.
The composition and
amount of leachate depend on many factors such as quality of wastes and its
crumbling, techniques of landfilling and degree of waste compaction, age of landfill,
biochemical and physical processes of waste decomposition, moisture and absorption
capacity of wastes, precipitation, humidity, and evapotranspiration rate, topography
of landfill site, lining system, hydrogeology, vegetation.
Precipitation and climate have the strongest influence on leachate generation,
causing the amount to vary during the year. Absorption capacity of wastes is another
affecting leachate production. Initial moisture of municipal wastes depends on type
of waste, seasonal trends, and treatment after collection and amounts on average to
33
35% of dry weight (Blakey, 1992). Additionally, wastes can absorb liquid up to the
moment when downward percolation begins. The absorption capacity is influenced
by waste density and pathways of liquid infiltrating through the deposit of wastes.
Generally, an increase of waste density decreases leachate production (Harrington,
1986 and Blakey, 1992).
The amount of leachate generated in municipal landfill can be calculated with
the following water balance equation (Blakey, 1992):
LP = P − ( R + ∆U + ET + ∆U W )
(4)
where: LP = leachate production, P = precipitation, R = surface runoff, ∆U = changes
in soil moisture storage, ET= evaporation from soil/evapotranspiration from a
vegetated surface, and ∆UW = changes in moisture content in wastes.
Landfill leachates are due to toxicity, classified as problematic wastewaters
and represent a dangerus source of pollution for the environment. Their purification
is difficult and often insufficient; therefore they seriously endanger the quality of the
surface and underground waters (Tjasa et.al., 1997).
The characteristics of the landfill leachates can usually be represented by the
basic parameters COD, BOD, ratio of BOD/COD, colour, NH3-N, pH, alkalinity,
oxidation-reduction potential and heavy metal (Wang, 2004).
2.7.2
Leachate Composition
More than 200 organic compounds have been identified in leachate. They
may be classified as cyclic hydrocarbons, bicyclic compounds, aromatic
hydrocarbons, substituted benzenes, alcohols and ethers, cyclic ethers, ketones and
ene-ones, acids and esters, phenols, phthalates, furans and nitrogen-, phosphorus-,
sulfur-, and silica-containing compounds, and others that remain unidentified.
34
Among the abovementioned compounds are 35 substances recognized as priority
pollutants (Michal, et. al, 2004).
Many factors influence leachate production and composition, resulting in a
different amount and quality of leachate produced in a particular landfill. Moreover,
the composition of leachate is changed significantly by the anaerobic processes
occurring in the deposit of wastes and age of landfill (Harrington, 1986). As an
example, Table 2.5 shows the composition of leachate for a new landfill and a
mature landfill. Moreover, according to Harrington et al. (1986), the composition of
leachate is change significantly by the anaerobic processes occurring in the deposit
of wastes and age of landfill, as an example, Table 2.4 shows the composition of
leachate from different sources, which point at highly varying ranges of respective
parameters. The leachate characteristics showed a wide variation depending on
tropical climatic changes such as monsoon and dry periods, similar to those found in
other places (Tchobanoglous et. al., 1993).
Table 2.4: Landfill leachate composition from three different sources
(Harrington et al., 1986)
Parameter
Range
Range
Range
pH
4.5-9.0
5.8-7.5
5.3-8.5
COD (mg/L)
500-60,000
100-62,000
150-100,000
BOD (mg/L)
20-40,000
2-38,000
100-90,000
Sulfate (mg SO4/L)
10-1,750
60-460
10-1,200
Chloride (mg Cl/L)
100-5,000
100-3,000
30-4,000
Ammonia nitrogen (mg N-NH4/L)
30-3,000
5-1,000
1-1,200
Young landfill leachate contains large amount of free volatile fatty acid,
resulting in high concentration of COD, BOD, NH3-N and alkalinity, a low
oxidation-reduction potential and black colour. Therefore, biological processes are
commonly employed for young landfill leachate treatment to remove the bulk
biodegradable organics (Wang, 2004). Old landfill leachate or biologically treated
young landfill leachate has a large percentage of recalcitrant organics molecules. As
a result, this kind of leachate is characterized by high COB, low BOD, fairly high
NH3-N and alkalinity, low ratio of BOD5/COD, a high oxidation-reduction potential
35
and dark brown or yellow colour. The treatment processes for this kind of leachate
include chemical precipitation and coagulation, chemical oxidation, electrochemical
oxidation, reverse osmosis and nanofiltration (Wang, 2004).
Table 2.5: Landfill Leachate Composition from new and mature landfill
(Tchobanoglous et. al., 1993).
New landfill < 2 years
Constituent
Range
Typical
Mature landfill
years > 10
BOD5
2000-30000
10000
100-200
TOC
1500-20000
6000
80-160
COD
3000-6000
18000
100-500
Total suspended solid
200-2000
500
100-400
Organic nitrogen
100-800
200
20-40
Ammonia nitrogen
10-800
200
20-40
Nitrate
5-40
25
5-10
Total phosphorus
5-100
30
5-10
Orthophosphorus
4-80
20
4-80
Alkalinity as CaCO3
1000-10000
3000
200-1000
pH
4.5-7.5
6
6.6-7.5
Total hardness
300-1000
3500
200-500
Calcium
200-3000
1000
100-400
Magnesium
50-1500
250
50-200
Potassium
200-1000
300
50-400
Sodium
200-2500
500
100-200
Chloride
200-3000
500
100-400
Sulfate
50-1000
300
20-50
Total iron
50-1200
60
20-200
All units in mg/l
As landfill ages, the pH of leachate also undergoes changes. Owing to the
stability of the second, methanogenic phase of anaerobic waste decomposition, the
pH of leachate increases to 8.5-9.0 (Henry, 1987). The degree to which landfill age
and waste decomposition influence the BOD5/COD ratio and pH of leachate is
presented in Table 2.6.
36
Table 2.6: Landfill Aged Influence on BOD5/COD Ratio and pH of leachate
(Henry, 1987 and Amokrane, 1997)
Landfill age
Young (<5years)
Mature (ageing)
Old (>10years)
2.8
Degree of waste
decomposition
Fresh, not decomposed wastes
Partially decomposed
Well-stabilized wastes
pH of
leachate
<6.5
6.5-7.5
>7.5
BOD5/COD
ratio
0.7
0.5-0.3
0.1
Leachate Contol Strategies
The leachate control strategies cover of waste input, control of water input,
control of landfill reactor and control of leachate dischage into the environment
(Christensen et al., 1992).
To control waste input, the amount of waste to be landfilled should be
reduced to a minimum level (Wang, 2004). The reduction of waste can be done by
separation of collection activities, recycling centers, incineration and composting.
Separation of hazardous fractions of municipal waste such as batteries, paint, expired
medicine and pesticide can reduce heavy metal and other toxic compounds
concentration in leachate.
To control water input depends on the quality of waste to be landfilled (SBC,
2002). For non-biodegradable waste, water infiltration should be prevented through
introduction of top sealing. For biodegradable waste, water input must be given so
that a certain degree of biostabilization can be obtained. To control the water input,
there are several important parameters to be considered. The parameters are siting of
landfill in low precipitation areas, usage of cover and topsoil systems that are
suitable for vital vegetation and biomass production, vegetation of the topsoil with
species which optomize the evaporation effect, surface lining in critical hydrological
conditions, limitation on sludge disposal, surface water drainage and diversion high
compaction of the refuse in the place and measures to prevent risks of cracking
owing to differential settlement (Christensen et al., 1992).
37
2.9
Type of Landfill
Landfill is land disposal sites that employ an engineering method of solid
waste disposal to minimize environmental hazards and protect the quality of surface
and subsurface waters (Pankratz, 2001).
Landfill sites are classified into 5 types according to structure as shown in
Table 2.7 and Figure 2.16. In terms of quality of leachate and gases generated from
landfill site, either semi-aerobic or aerobic landfill method is desirous.
Table 2.7: Classification of Landfill Structure (Pankratz, 2001)
Types of Landfill
Classification
Anaerobic landfill
Solid wastes are filled; in dug area of plane field or valley.
Wastes are filled with water and in anaerobic condition.
Anaerobic sanitary
landfill
Anaerobic landfill with cover like sandwich shape.
Condition in solid waste is same as anaerobic landfill.
Improved anaerobic
sanitary landfill
(Improved sanitary
landfill)
This has leachate collection system in the bottom of the
landfill site. Others are same as anaerobic sanitary landfill.
The condition is still anaerobic and moisture content is
much less than anaerobic sanitary landfill.
Semi-aerobic landfill
Leachate collection duct is bigger than the one of improved
sanitary landfill. The opening of the duct is surrounded by
air and the duct is covered with small crushed stones.
Moisture content in solid waste is small. Oxygen is
supplied to solid waste from leachate collection duct.
Aerobic landfill
In addition to the leachate collection pipe, air supply pipes
are attached and air is enforced to enter the solid waste of
which condition becomes more aerobic than semi-aerobic
landfill.
38
Figure 2.16: Classification of landfill structures (Chew, 2005)
CHAPTER 3
RESEARCH METHODOLOGY
3.1
Introduction
In this chapter, the methodology applied in order to carry out the tests and
analysis on the treatment of leachate using free water surface constructed wetlands
(FWSCW) is discussed. The pilot scale experiments on FWSCW treatment of
landfill leachate were conducted under ambient condition with an average
temperature of about 30˚C. Sanitary landfill leachate samples, collected from
Tanjung Langsat, Pasir Gudang municipal landfill site, located 42 km north-east of
Johor. This sanitary landfill began its operations in June 2002.
The experiments were conducted separately in the three (3) cells filled with
different leachate concentration where Cell A is 50% leachate concentration, Cell B
is 33% leachate concentration and Cell C act as control unit where there is no
Limnocharis flava was planted. Same number of wetland plants (60 no. of plants),
Limnocharis flava is placed in each of the two cells for leachate treatment. Sequence
of the experiment was conducted as shown in Appendix D. Figure 3.1 shows the
simplified research methodology.
40
Experimental Set Up
Set up of pilot scale constructed
wetlands
Experimental Works
System 1
System 2
Cell A with 50%
leachate
concentration and
40 no.m-2 to 60
no.m-2 of plant
Cell B with 33%
leachate
concentration and
40 no.m-2 to 60
no.m-2 of plant
Sampling and Preservation
Data Analysis
•
•
Based on the parameter observed
in the experiment
Removal efficiencies of pollutant
Conclusions and recommendation
Figure 3.1: The framework of study
41
3.2
Experimental Set Up and Operating Conditions of Constructed Wetland
Three pilot scale FWSCW units, made of reinforce concrete, were built at the
Environmental Laboratory, Faculty of Civil Engineering, Universiti Teknologi
Malaysia, each with a dimension of 0.5m x 4.0m x 0.5m (width x length x depth),
and a bed slope of 1% (Sawaittayothin and Chongrak, 2006) as shown in Plate 3.1.
The support media of these units consisted of large gravel (2 cm in diameter),
medium gravel (1 cm in diameter) and sand at depth 10 cm, respectively. Gravel was
selected because of its high hydraulic conductivity, ease of maintenance and
consistency of specification, allowing greater predictability of performance than
other soil media (Barr and Robinson, 1999).
Plate 3.1: Lab-scale constructed wetland
A species of wetland plant called Limnocharis flava (yellow burhead)
illustrated in Figure 3.2 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 plants were planted at a density of
60 no.m-2 for each unit. The campus domestic wastewater was fed continuously for
one week to the FWSCW units to acclimatize the soil microbes and to support
growth of the yellow burhead plant.
After the plants were fully grown to an average height of 3 cm, the FWSCW
units were continuously fed with the diluted landfill leachate for one week to let the
FWSCW units used to new condition. After that, the landfill leachate diluted with tap
water and fed into the FWSCW unit as shown in Plate 3.3 and 3.4 according to the
42
concentration chosen. The effects of different concentration on the treatment
performance of FWSCW were studied by varying the hydraulic retention time (HRT)
at 3, 6 and 9 day and the efficiencies of the system in terms of percentage removal of
the pollutant. Harvesting of the yellow burhead plants was conducted once every two
weeks by cutting the plant stems at about 30 cm above the FWSCW beds. About
50% of the burhead plants were harvested and 70% of the burhead plants were
planted each time to allow for the FWSCW beds to maintain treatment efficiencies.
The different concentrations of leachate are use for this study were Cell A is 50%
leachate and 50% tap water (1 leachate:1 water) and Cell B is 33% leachate and 67%
tap water (1 leachate:2 water).
All the physical, chemical and biological parameters of the wastewater were
analyzed according to the methods described in Standard Methods for the
examination of water and wastewater (APHA, 2002).
Yellow burhead belongs to Limnocharitaceae family. It is a perennial herb
that is native to tropical America and West Indies. This herb is a large hydrophyte
and can reach 70 cm in height. The leaves are rice paddle-shaped and soft. It blooms
yellow trefoil flowers on the trigonal floral axes. The young leaves and flowers are
used for a spicy herb or fodder in tropical areas. The characteristics of the
Limnocharis flava as stated in Table 3.1.
Figure 3.2: Limnocharis flava (yellow burhead)
43
Table 3.1: The characteristics of the Limnocharis flava
Alternative Name(s): Yellow Burrhead.
Family: Limnocharitaceae.
Form: Water plant
Origin: Native from Mexico to Paraguay and to the Caribbean
Islands.
Flowers/Seedhead: Flowers: At the end of long stems.
Flowers recurving when fruiting and fruit buried in mud or
water. Flowers year round.
Description: Perennial herb to 1 m high and rooting in mud.
Leaves broad-ovate, thick, 5–30 cm long, 4–25 cm wide, leaf
stalk (petiole) 5–75 cm long, green. Fruit compound, to 2 cm
wide, each fruit containing about 1,000 seeds. Seeds dark
brown, horseshoe-shaped, to 1.5 mm long with obvious ridges.
(Source: http://www.weeds.org.au/)
Plate 3.2: Dilution of landfill leachate before pour into the cells
44
50%
33%
Plate 3.3: Different concentration of leachate used during
the experiment
3.3
Experimental Analysis
The entire tests were carried out in Environmental Laboratory, Faculty of
Civil Engineering, Universiti Teknologi Malaysia. The tests include parameter such
as Total suspended solid (TSS), turbidity, biochemical oxygen demand (COD), test
for nutrients such as nitrate, ammonia, phosphorus, manganese, and iron.
3.3.1
Analysis of Leachate
The leachate was sampled in each of two cells by using grab sampling
according to the standard methods (APHA, 2002). Sampling was done every 3, 6 and
9 days according to the HRT used and the analysis for each parameter was done in
Environmental Laboratory, Faculty of Civil Engineering, Universiti Teknologi
Malaysia, Skudai Johor. The parameter for leachate analysis was listed as follow:
45
(a)
Turbidity
Turbidity test was conducted according to the Standard Method APHA by
using Spectrophotometer HACH DR 4000 Model, method used is 10047 (Attenuated
Radiation Method – Direct Reading) and Hach program is 3750.
(b)
Biochemical Oxygen Demand
Biochemical Oxygen Demand (COD) test was conducted according to the
Standard Method APHA by using Spectrophotometer HACH DR 4000 Model,
method used is 8000 (Reactor Digestion Method) and Hach program is 2720.
(c)
Ammonia Nitrogen
Ammonia Nitrogen (NH3-N) analysis was conducted according to Standard
Method APHA 4500-NH3-N by using Spectrophotometer HACH DR 4000 Model,
method used is 8038 (Nessler Method) and Hach program is 2400.
(d)
Nitrate Nitrogen
Nitrate Nitrogen (NO3—N) analysis was conducted according to the Standard
Methods APHA 4500- NO3--N by using Spectrophotometer HACH DR 4000 Model,
method used is 8093 (Cadmium Reduction Method) and Hach program is 2530.
(e)
Orthophosphate
Orthophosphate (PO43-) analysis was conducted according to the Standard
Methods APHA 4500-P (C) by Spectrophotometer HACH DR 4000 Model, method
used is 8048 (PhosVer 3 – Ascorbic Acid Method) and Hach program is 3025.
46
(f)
Total Iron
Total iron was measured according to the Standard Methods APHA 3500-Fe
(B) by using Spectrophotometer HACH DR 4000 Model, method used is 8112
(TPTZ Method) and Hach program is 2190.
(g)
Manganese (Mn)
Manganese was measured according to the Standard Methods APHA 3500-
Mn (B) by using Spectrophotometer HACH DR 4000 Model, method used is 8034
(Periodate Oxidation Method) and Hach program is 2250.
CHAPTER 4
RESULTS AND DISCUSSION
4.1
Introduction
In this chapter, the results from the laboratory analysis of the FWSCW will
be analyzed and discussed in details. The data will be shown in graphical approach to
evaluate the removal efficiency of the FWSCW system in treating landfill leachate.
The experimental studies were carried out for five months from May until
September. The effluent from the FWSCW was conclusively subdivided into three
categories, namely the physical parameters (TSS and Turbidity), nutrients (NH3-N,
NO3-N, P, Mn and Fe) and the organic matter (COD) The difference leachate
concentration was compared to evaluate the trends for the overall performance.
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, 50% leachate concentration and 33% leachate concentration)
and comparing significant differences between HRT 3, 6 and 9 days.
48
4.2
Pollutant Removal in Leachate
The quality of the pre-treated leachate taken from the Tanjung Langsat
municipal landfill site, had characteristics as shown in Table 4.1. These data were
obtained from analyses of leachate samples collected six times during the study. The
quality of leachate, which is taken from the landfill, was found not to comply with
Standard B under Environmental Quality (Sewage and Industrial Effluent)
Regulations 1979 as shown in Appendix A.
Table 4.1: Characteristics of landfill leachate used in FWSCW experiments
Parameters
Unit
Range
Average
SD
COD
mg/L
192-446
297.45
163.07
Orthophosphate
mg/L
48.9-52.7
50.84
9.42
Nitrate-nitrogen
mg/L
77.2-195
135.43
60.65
Ammonia-nitrogen
mg/L
26.3-69.68
52.6
25.34
Manganese
mg/L
0.66-2.0
1.16
0.78
Iron
mg/L
0.02-0.42
0.55
0.72
Zinc
mg/L
0.003-0.04
0.071
0.08
Chromium
mg/L
0.02-0.08
0.16
0.15
Turbidity
FAU
2-6
4.95
1.97
Suspended solid
mg/L
2.5-7.5
1.53
0.70
SD = standard deviation; FAU = Formazin Attenuation Units
The quality of pre-treated landfill leachate after being 50% and 33% diluted
as shown in Table B1 (Appendix B) and the effluent quality after the leachate was
treated accordingly to the HRT by using the FWS constructed wetlands are
summarize in Table 4.2 and Table 4.3, while Table 4.4 shows the effluent quality for
the control unit. The percentages of removal for three (3) cells in terms of hydraulic
retention time (HRT) are depicted in Table 4.5, 4.6 and 4.7.
All the parameters are given in milligram per liter (mg/l) except for turbidity
given in FAU (Formazin Attenuation Units). A FAU is equivalent to a NTU
(Nephelometric Turbidity Units).
49
Table 4.2: Effluent concentration after treated by FWSCW for Cell A
Description
NH3-N (inf)
NH3-N (eff)
NO3-N (inf)
NO3-N (eff)
PO43- (inf)
PO43- (eff)
COD (inf)
COD (eff)
Mn (inf)
Mn (eff)
Zn (inf)
Zn (eff)
Fe (inf)
Fe (eff)
Turbidity (inf)
Turbidity (eff)
TSS (inf)
TSS (eff)
Experimental unit HRT (day)
(Cell A)
3
6
9
66.35
66.95
66.15
12.85
4.91
16.03
54.53
55.00
55.17
9.34
8.51
16.36
4.38
4.95
3.69
1.09
0.64
0.35
279
289
248
93
25
55
1.15
2.83
1.15
0.15
0.12
0.12
0.32
0.22
0.24
0.04
0.01
0.03
0.20
0.18
0.17
0.05
0.01
0.05
4.00
4.00
4.00
1.00
0.00
0.00
0.05
0.05
0.05
0.005
0.005
0
All units in mg/l, except for turbidity = FAU (Formazin Attenuation Units)
Table 4.3: Effluent concentration after treated by FWSCW for Cell B
Description
NH3-N (inf)
NH3-N (eff)
NO3-N (inf)
NO3-N (eff)
PO43- (inf)
PO43- (eff)
COD (inf)
COD (eff)
Mn (inf)
Mn (eff)
Zn (inf)
Zn (eff)
Fe (inf)
Fe (eff)
Turbidity (inf)
Turbidity (eff)
TSS (inf)
TSS (eff)
Experimental unit HRT (day)
(Cell B)
3
6
9
27.83
31.58
27.98
4.70
6.61
7.05
15.15
15.92
15.30
4.10
0.35
6.90
3.16
2.92
3.31
0.38
0.07
1.46
265
296
266
60
55
95
1.10
1.18
1.10
0.10
0.14
0.20
0.06
0.09
0.07
0.05
0.01
0.04
0.21
0.23
0.31
0.02
0.04
0.06
4.00
4.00
4.00
0.00
0.00
0.00
0.05
0.05
0.05
0.005
0.005
0
All units in mg/l, except for turbidity = FAU (Formazin Attenuation Units)
50
Table 4.4: Effluent concentration after treated by FWSCW for control unit
Description
NH3-N (inf)
NH3-N (eff)
NO3-N (inf)
NO3-N (eff)
PO43- (inf)
PO43- (eff)
COD (inf)
COD (eff)
Mn (inf)
Mn (eff)
Zn (inf)
Zn (eff)
Fe (inf)
Fe (eff)
Turbidity (inf)
Turbidity (eff)
TSS (inf)
TSS (eff)
Experimental unit HRT (day)
(control unit)
3
6
9
69.67
69.18
68.38
39.14
50.94
20.61
70.55
78.24
67.14
50.92
25.64
50.14
53.80
48.43
55.25
41.33
7.73
12.32
403
461.5
400
40.40
30.02
50.40
2.00
2.00
2.20
1.03
0.48
1.14
0.43
0.39
0.10
0.08
0.08
0.06
0.42
0.31
0.42
0.35
0.18
0.15
6.00
5.00
7.10
0.08
0.05
0.05
7.5
0.02
0.15
0.005
0
0
All units in mg/l, except for turbidity = FAU (Formazin Attenuation Units)
Table 4.5: Removal efficiencies in FWSCW at HRT 3 day
Description
NH3-N
NO3-N
PO43COD
Mn
Zn
Fe
Turbidity
TSS
Cell A
80.63 %
82.88 %
75.11 %
66.67 %
86.96 %
84.38 %
74.87 %
75 %
90 %
HRT = 3 day
Cell B
Control unit
83.11 %
43.82 %
72.94 %
27.82 %
23.18 %
88.07 %
77.36 %
89.98 %
90.91 %
48.50 %
19.13 %
80.93 %
16.67 %
91.71 %
98.67 %
100 %
99.93 %
90 %
51
Table 4.6: Removal efficiencies in FWSCW at HRT 6 day
Description
NH3-N
NO3-N
PO43COD
Mn
Zn
Fe
Turbidity
TSS
Cell A
92.67 %
84.53 %
87.07 %
91.35 %
89.57 %
94.96 %
94.44 %
100 %
90 %
HRT = 6 day
Cell B
Control unit
79.07 %
26.36 %
97.81 %
67.23 %
97.67 %
84.04 %
81.42 %
93.50 %
88.14 %
76 %
90.32 %
79.33 %
83.04 %
41.29 %
100 %
99 %
9%
100 %
Table 4.7: Removal efficiencies in FWSCW at HRT 9 day
Description
NH3-N
NO3-N
PO43COD
Mn
Zn
Fe
Turbidity
TSS
4.3
Cell A
75.76 %
70.36 %
90.65 %
77.82 %
89.57 %
86.29 %
69.64 %
100 %
100 %
HRT = 9 day
Cell B
Control unit
74.80 %
69.86 %
54.89 %
25.32 %
55.95 %
77.70 %
64.29 %
87.40 %
81.82 %
48.18 %
42.47 %
45.00 %
79.34 %
63.33 %
100 %
99.35 %
100 %
100 %
Water Quality Analysis
There are several water quality parameters such as pH, alkalinity,
conductivity, dissolved oxygen, temperature, colour and etc. However, only two
water quality parameter that consider in this study, namely, total suspended solid
(TSS) and turbidity. Turbidity is a water quality parameter that refers to how clear
the water is. The greater the amount of total suspended solids (TSS) in the water, the
murkier it appears and the higher the measured turbidity. Analysis for both
parameters will be discussed in detailed in next sub-section.
52
4.3.1
Total Suspended Solid Removal
Suspended solids were identified as one of the contaminants of concern in
most landfill leachate effluent. Total suspended solids (TSS) include all particles
suspended in water that will not pass through a filter. Abundant suspended solids
such as clay and silt, fine particles of organic and inorganic matter (such as iron
particulate), soluble coloured compounds and phytoplankton can result in; decreased
light penetration in water reducing photosynthesis of water plants, decreased water
depth due to sediment build-up, the smothering of aquatic vegetation, habitat and
food, the smothering of macro and micro-organisms, larva, eggs and the clogging of
fish gills, the reduced efficiency of predation by visual hunters, and increased heat
absorbed by the water, lowering dissolved oxygen, facilitating parasite and disease
growth and increasing the toxicity of ammonia (Mason, 1998; and Boulton and
Brock, 1999).
Suspended solid removal in constructed wetlands is best facilitated through
the encouragement of settling. Effective settling in treatment wetland systems is most
commonly accommodated by the creation of a settling pond or a forebay at the head
of the wetland. They are typically designed to support long retention times in order to
allow the suspended solids and other debris to settle out. The increased depth
accommodates sediment build up, reducing the need for frequent dredging
(Tousignant et al., 1999).
On comparing the performance of different concentration, greater level of
TSS removal was observed in control unit at HRT 6 day was 100% removal, whereas
at HRT 9 day the greatest level of TSS removal occur in Cell A, B and control unit
with removal of 100% as shown in Figure 4.1. Roser et al. (1987) has reported that
the percentage removal of TSS for retention times 3-5 days is 89% compared to
retention times 6-9 days is 94%. It shows that the higher retention time, gives the
higher TSS removal. Other study performed by Gersberg et al. (1986), the removal
efficiencies for the vegetated beds were not significantly different from the
unvegetated bed. They concluded that the removal of SS was almost due entirely to
sedimentation and filtration rather than biological processes.
53
Moreover, the percentage of removal for those cells can reach up 100%
removal at HRT 9 days as shown Figure 4.1. The figure shows obviously increase in
TSS for control unit.
100
TSS removal (%)
98
96
94
Control unit
92
Cell A
90
Cell B
88
86
84
3
6
HRT (days)
9
Figure 4.1: Percentage of removal for Cell A and B for total suspended solids (TSS).
The FWSCW system can reach until 100% removal for both cells.
The TSS concentrations in those cells are shown in Figure 4.2 where the
concentration at HRT 6 and 9 day reaches 0 mg/l. According to Chongrak and Lim
(1998), settleable solids are removed easily via gravity sedimentation as wetland
systems generally have long hydraulic retention times (HRT). It was believed that all
the particles are trapped in the media. It shows that the media plays an important role
in terms of removal of suspended solid as well as to support the growth of rooted
emergent plant. According to Davit et al. (2001), solids are removed by physical
filtration and settling within the gravel/root hair matrix. Organic matter may also be
removed by these physical processes, but is ultimately removed through
biodegradation.
TSS concentration (mg/l)
54
0.0050
0.0045
0.0040
0.0035
0.0030
0.0025
0.0020
0.0015
0.0010
0.0005
0.0000
Control unit
Cell A
Cell B
3
6
HRT (days)
9
Figure 4.2: Concentration of TSS as a function of sampling day for Cell A, B as well
as control unit where the concentration at HRT 9 day reaches 0 mg/l. It was believed
that all the particles are trapped in the media.
4.3.2
Turbidity Removal
Figure 4.3 illustrate the overall performance of turbidity removal for Cell A,
B and control unit free water surface constructed wetland systems in terms of
different hydraulic retention time (HRT).
100
Tubidity removal (%)
90
80
70
60
Control unit
50
Cell A
40
Cell B
30
20
10
0
3
6
HRT (day)
9
Figure 4.3: Percentage removal for Cell A, B and control unit in different HRT. The
percentage removals are increasing steadily where the system can reach until 100%
removal for those cells in FWSCW.
55
As TSS, similar trend was observed in turbidity removal. On comparing the
performance of different HRT, greater level of turbidity removal was observed at
HRT 6 and 9 day for Cell A, B and control unit as well where the removal are 100%,
100% and 99% respectively. While for HRT 3 day, the removal are 75%, 100% and
Turbidity concentration (FAU)
98.67% for Cell A, B and control unit.
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
Control unit
Cell A
Cell B
3
6
HRT (day)
9
Figure 4.4: The turbidity concentration with different HRT for Cell A, B and control
unit where the leachate concentration are decrease due to sedimentation and filtration
that occur during the process.
Figure 4.4 shows the reduction of turbidity up to 0 FAU due to sedimentation
and filtration. However, at HRT 3 d, turbidity removal for Cell A is 1 FAU but others
is less than 0.1 FAU. Typically, a biological process associated with the plants was
not contributed to turbidity removal since the percentage between both
concentrations was not significantly different (Nazaitulshila, 2006).
Results are given in FAU (Formazin Attenuation Units) not Nephelometric
Turbidity Units (NTU). A FAU is equivalent to a NTU.
56
4.4
Organic Matter Analysis
4.4.1
Biochemical Oxygen Demand Removal
For this research, the biodegradable organic matter being studied in landfill
leachate is Chemical Oxygen Demand (COD). In wetland systems, microbial
degradation plays a dominant role in the removal of soluble/colloidal biodegradable
organic matter (BOD or COD) in wastewater, the remaining BOD associated with
settleable solids being removed by sedimentation (Chongrak and Lim, 1998).
However, the BOD test is neglect in this study due to shortage of time and
equipment.
Figure 4.5 showed the COD removal efficiency in control experiment and
different leachate concentration with different HRT wetlands with exposure to
natural environmental condition.
100
90
COD removal (%)
80
70
60
Control Unit
50
40
Cell A
30
Cell B
20
10
0
3
6
HRT (day)
9
Figure 4.5: The percentage of removal of COD for Cell A, B and control unit. The
removals are increase steadily up to 94% removal in control unit. On the other hand,
the removal of control unit higher than Cell A and B which was probably due to the
presence of non-biodegradable organic compounds in the landfill leachate.
The treatment performance of the three (3) units operating at the various HRT
is shown in Table 4.2 through 4.7. At steady state conditions, the FWSCW units
operating at HRT of 6 day had more than 80% of organic (COD) removal for Cell A,
57
B and control unit with the effluent COD concentrations being less than 100 mg/L as
shown in Figure 4.6 which is comply with Standard B under Environmental Quality
(Sewage and Industrial Effluent) Regulations 1979. COD is used to evaluate the
organic strength of domestic and industrial wastewaster (Pouliot, 1999). It measures
the amount of oxygen necessary to complete oxidize all organic matter. The
percentages of COD removal in the experimental FWSCW unit of Cell A (50%
concentration) and Cell B (33% concentration) are slightly higher than those control
unit which was probably due to the presence of non-biodegradable organic
COD concentration (mg/l)
compounds in the landfill leachate.
100
90
80
70
60
50
40
30
20
10
0
95.00
93
60
55.00
55
50.40
Control unit
Cell A
40
30
3
Cell B
25
6
HRT (day)
9
Figure 4.6: The effluent quality for Cell A, B and control unit with different HRT.
The highest COD removal occurs in Cell B at HRT 9 day with 95.0 mg/l. The
effluent quality for HRT 3 day can be observed in Cell A with 93.0 mg/l.
Chemical oxygen demand (COD) is a measure of the amount of the oxygen
required to chemically oxidize reduced minerals and organic matter. It does not
differentiate between biologically available and inert organic matter (Galbrand,
2003). In general, the greater the COD value in water, the more oxygen influent
demands, from the water body, thus resulting in depleted dissolved oxygen which is
essential to the metabolisme of all aerobic aquatic organisme (Silva et. al., 2003;
Cusso et. al., 2001).
According to Crites and Tchobanoglous (1998), the COD removal in control
unit increased due to the algae decay that released and recycled back the organic and
inorganic matter in the leachate. Thus, the COD in the control unit did not decrease
58
but increased throughout the experiment as illustrated in Figure 4.5. As reported by
Wood et al. (1989), the poor COD removal efficiency was due to the high surface
loading rate and incapacity of the macrophytes to meet the oxygen demand.
4.5
Chemical Water Quality Analysis
4.5.1
Ammonia Nitrogen Removal
Ammonia was identified as one of the contaminants of concern in most
landfill leachate effluent. Ammonia nitrogen is a pungent, gaseous compound of
nitrogen and hydrogen and includes both ammonia (NH3) and ammonium ion (NH4-).
More common in landfill leachate is the ionized form NH4+ which is formed when
NH3 is combined with water at pH less than 8.5 and low temperatures to produce an
ammonium ion and a hydroxide ion (OH-) (Galbrand, 2003). Ammonia
concentrations are typically less than 0.1 mg/l in natural waters.
Figure 4.7 depicted the NH3-N removal efficiency of Cell A, B and control
unit under different hydraulic retention time (HRT) with exposure to natural
environmental condition.
92.67
100
Ammonia nitrogen removal
(%)
90
80.63
83.11
79.07
80
69.86
75.7674.80
70
60
50
43.82
Control Unit
40
Cell A
26.36
30
Cell B
20
10
0
3
6
HRT (day)
9
Figure 4.7: The percentage of removal for NH3-N with different hydraulic retention
time (HRT). The highest removal can be obtained in Cell A at HRT 6 day. The
lowest removal of NH3-N occurs in control unit with 26% at HRT 6 day.
59
Removal of ammonia nitrogen (NH3-N) was the highest in Cell A under three
different HRT which is 81% removal at HRT 3 day, 93% removal at HRT 6 day and
76% removal at HRT 9 day. An overall, the lowest removal can be obtained at HRT
9 day where the removals are 70% removal in control unit, 76% removal in Cell A
and 75% removal in Cell B due to the plant wilting. As reported by El-Gendy (2003),
plant wilting will increase the nutrient concentration in leachate which included NH3N.
Figure 4.7 indicated the significance of HRT on treatment performance of
FWSCW. The HRT 3 and 9 day were found to be too short and too long for the
FWSCW units to effectively treat the landfill leachate. According to Chongrak and
Lim (1998), the HRT is one of the major factors affecting the treatment performance.
In general, a too long HRT can result in stagnant anaerobic conditions whereas the
shorter HRT do not provide sufficient time for degradation of pollutants. However,
the best performance of NH3-N can be obtained at HRT 6 day.
Plant uptake for NH3-N was not significant in the wetlands since the NH3-N
removal efficiency in control unit is nearly to removal efficiency in Cell A and B.
Thus, most of the NH3-N removal mechanisms involved in nitrification by
Nitrosomonas and Nitrobacter bacteria (Boulton and Brock, 1999). However, the
plants provided aerobic zone in the root for nitrification to be occurred as reported by
Chongrak and Lim (1998).
4.5.2
Nitrate Nitrogen Removal
In aerobic conditions, nitrite is typically rapidly oxidized to nitrate by
Nitrobacter bacteria. Nitrate is an inorganic compound of nitrogen which is
bioavailable for plant uptake and is essential to plant growth (Boulton and Brock,
1999; Freedman, 2001). Natural levels of nitrate in waterbodies are typically lower
than 1 mg/l where nitrite and ammonia are toxic, nitrate is virtually harmless, with
direct toxic effect typically not observed until concentrations greater than 1000 mg/l
(Mason, 1998). However, if phosphorus concentrations are sufficient, high nitrate
60
content in waters can increase the severity of eutrophication, which can have chronic
effects of aquatic life.
In this study, only ammonia nitrogen (NH3-N) and nitrate (NO3-N) will be
considered, the others are possible due to their transformation are to short and the
limitation of the laboratory apparatus. Nitrification is usually defined as the
biological oxidation of ammonium to nitrate with nitirite as an intermediate in the
reaction sequence. The nitrate nitrogen (NO3-N) removal in the FWSCW unit ranged
from 28% to 83% for HRT 3 day, 67% to 98% for HRT 6 day and 25% to 70% for
HRT 9 day. The laboratory analyses for the effluent of the FWSCW are shown in
Nitrate-nitrogen removal (%)
Figure 4.8.
97.81
100
84.53
82.88
90
72.94
70.36
80
67.23
70
54.89
60
50
40 27.82
25.32
30
20
10
0
3
6
9
HRT (day)
Control Unit
Cell A
Cell B
Figure 4.8: The percentage of removal for NO3-N with different hydraulic retention
time (HRT). The highest removal can be obtained in Cell B at HRT 6 day with
removal 98%. The lowest removal of NO3-N occurs in control unit with 25% at HRT
9 day.
Figure 4.8 indicates the overall performance of NO3-N removal efficiency of
three different hydraulic retention times (HRTs) in FWSCW with expose to natural
environmental condition.
NO3-N removal in control unit is slightly lower due to unvegetated beds. In
comparison among three cells, Cell B was the most efficient in removing NO3-N
which was 98%. On the other hand, the best HRT for NO3-N removal is HRT 6 day
where 67% removal achieved in control unit instead of 28% and 25% at HRT 3 and 9
61
days, 85% NO3-N removal can be obtained in Cell A (HRT = 6 day) instead of 83%
and 79% in HRT3 and 9 days, and the highest removal occurred in Cell B with 98%
removal instead of 73% and 55% at HRT 3 and 9 days. As a conclusion, the best
HRT in terms of NO3-N removal is HRT 6.
According to Gersberg et al. (1983), the plant uptake was not a significant
pathway in the overall nitrogen removal and that the major loss of nitrogen from the
system was due to denitrification. Moreover, Gersberg et al. (1986) investigated the
wetland beds planted achieved ammoniacal nitrogen efficiencies of 94% as
compared with only 11% for unvegetated beds at the HLR of 4.7cm/d or HRT of 6
days. Research performed by Roser et al. (1987), both planted and unplanted gravel
beds yielded similar percentages of N removal. Average percentage of N removal
was about 51% for HRT of 3-5 day and 54% for HRT of 6-9 days.
NO3-N removal was lower in Cell A than Cell B due to the plant wilting that
eventually
increased
NO3-N
concentration
in
the
leachate
(Crites
and
Tchobanoglous, 1998). As stated by Nivala et al. (2006), low concentration of
effluent NO3-N can mean one of two thing; (Case I) that nitrification is not occurring
and NO3-N is not being formed (corresponding to minimal net removal of nitrogen),
or (Case II) that both nitrification and denitrification processes are occurring to
completion (corresponding to high net removal of nitrogen).
4.5.3
Orthophosphate Removal
Phosphorus in wetland occurs as phosphate in organic and inorganic
compounds. Free orthophosphate is the only form of phosphorus believed to be
utilized directly by algae and macrophytes and thus represents a major link between
organic and inorganic phosphorus cycling in wetlands. Moreover, according to Lee
and Jones-Lee (2001), the phosphorus is an essential macronutrient that is a limiting
factor to plant growth. It is essential to all life as a component of nucleic acids and a
universal energy molecule. In excess, phosphorus triggers eutrophic conditions
which involve the profilic growth of algal and other aquatic plants. Algal growth can
62
have lethal impacts on aquatic life and, at high concentrations, can be toxic in itself
(Galbrand, 2003).
Figure 4.9 indicates the PO43- removal efficiency under different hydraulic
retention time (HRTs) in FWSCW with expose to natural environmental condition.
97.67
100
Ortgophosphate removal (%)
90
80
88.07
75.11
87.07
84.04
90.65
77.70
70
55.95
60
Control Unit
50
40
30
Cell A
23.18
Cell B
20
10
0
3
6
HRT (day)
9
Figure 4.9: The percentage removal of orthophosphate under different HRT. The
highest removal can be obtained in Cell B at HRT 6 day with removal 98%. The
lowest removal of PO43- occurs in control unit with 23% at HRT 3 day.
PO43- removal efficiency was low in the control unit at HRT 3 day and HRT
9 days with removal of 56% in Cell B. According to Chongrak and Lim (1998), the
low removal efficiency was due to the reason that the plant uptake and
microoganisms biodegradation were not the major mechanisms in PO43- removal.
Instead, adsorption and precipitation was the major removal pathway where
phosphorus was adsorbed to the soils or precipitated with calcium/aluminium
(Kadlec and Knight, 1996; Boulton and Brock, 1999).
The highest removal efficiency can be obtained at HRT 6 days where Cell A
is 87% removal, Cell B is 98% removal and control unit is 84% removal. Research
performed by Roser et al. (1987), both planted and unplanted gravel beds yielded
similar percentages of P removal. The authors suggested that filtration was a
significant P removal mechanism as shown by the ability of the unplanted bed to
match the P removal efficiency achieved by the planted systems.
63
It shows not much different due to the settlement of the nutrient at the surface
of the soil media. As revealed by Rosolen (2000), the phosphorus absorbed onto
suspended sediments will be filtered out as the suspended solids are removed.
Phosphorus has very low solubility, and is readily moved from solution by several
precipitation and adsorption reactions by binding it in an insoluble form. Kim and
Geary (2000) reported that soil substrates are the ultimate sink for phosphorus.
The absorption of sunlight by algal blooms reduces amount of light reaching
aquatic plants in sediments. If an algal bloom is prolonged, aquatic plants will die.
Large amounts of decaying algae result in the consummation of large quantities of
oxygen by the bacteria and fungi that break it down. This results in the dramatic
reduction of oxygen concentrations in the water column, particularly at night. This
reduction affects invertebrate predators with high oxygen requirements. The
subsequent lack of predators results in critical disruptions in food chain and increases
of nuisance species such as mosquitoes. Algal blooms can also contain toxic strains
of
blue-green
algae
which
may
kill
birds,
domestic
animals,
aquatic
macroinvertebrates and even humans if consumed (Lee and Jones-Lee, 2001;
Sharpley et. al., 1994).
4.5.4
Manganese Removal
Manganese was also identified as one of the contaminants of concern in the
landfill leachate effluent needing treatment. Manganese (Mn) is a transition metal
which is grey, white of silver in colour. It is soft and ductile if pure but usually
occurs in compounds and complexes with organic compounds (Sample et. al., 1997).
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.
Manganese is an essential micronutrient forming a vital part of the enzyme
systems that metabolise proteins and energy in all animals (Galbrand, 2003). There
64
are about eight nutrients essential to plant growth and health that are only needed in
very small quantities. These are manganese, boron, copper, iron, chlorine, cobalt,
molybdenum, and zinc. Though these are present in only small quantities, they are all
necessary.
Figure 4.10 indicates the Mn removal efficiency for Cell A, B and control
unit under different hydraulic retention time (HRT) with exposure to natural
Manganese removal (%)
environmental condition.
90.91
100
89.57 88.14
89.57
86.96
81.82
90
76.00
80
70
48.18
60 48.50
50
40
30
20
10
0
3
6
9
HRT (days)
Control unit
Cell A
Cell B
Figure 4.10: The percentage removal of manganese under different HRT. The
highest removal can be obtained in Cell B at HRT 3 day with removal 91%. The
lowest removal of Mn occurs in control unit with 48% at HRT 9 day.
Different HRT that use in the FWSCW gives not much different in remove
manganese (Mn). At HRT 3 days 87% removal in Cell A, 91% removal in Cell B,
and 49% removal in control unit. Therefore, at HRT 6 days, 90% removal occurred
in Cell A, 88% removal in Cell B and 76% removal in control unit. The longer HRT
in this experiment is 9 days where 90% removal in Cell A, 82% in Cell B, and 48%
removal in control unit.
Mn uptake by plants Limnocharis flava was less than Fe. According to Kamal
et al. (2004), F2+ was the micronutrient for plants that was required in higher
concentration than Mn2+. Mn removal was slightly higher at HRT 3 days. This was
due to the plant wilting that minimized plant uptake for Mn (Soltan and Rashed,
2003).
65
4.5.5
Iron Removal
The iron (Fe) removal efficiency was observed in the study as shown in
Figure 4.11. The percentages of removal for three cells are fluctuating. At HRT 6
days, the iron (Fe) concentrations are increased due to the accumulation of the iron in
the media bed. Iron (Fe) removal in the FWSCW was rather effective, where the
94% removal in Cell A and 83% in Cell B at HRT 6 days. Also, over the course of
sampling, the iron concentration at HRT 9 days fluctuated drastically than HRT 3
and 6 days, decreasing throughout the rainy days. Rain likely brought more iron into
the treatment wetland. The lowest percentage removal of manganese can be obtained
at HRT 9 days where 70% removal in Cell A, 79% removal in Cell B and 63%
Iron removal (%)
removal in control unit.
100
90
80
70
60
50
40
30
20
10
0
94.44
91.71
83.04
74.87
79.34
69.64
63.33
41.29
Control unit
Cell A
Cell B
16.67
3
6
HRT (day)
9
Figure 4.11: The percentage removal of iron (Fe) under different HRT. The highest
removal can be obtained in Cell A at HRT 6 days with removal 94%. The lowest
removal of Mn occurs in control unit with 17% at HRT 3 days.
As reported by King et al. (1992), Fe is an essential micronutrient element
required by both plants and wildlife at significant concentrations. 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 of 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
66
which were n root system and foliar surface (Sawidis, et al., 2001). Nevertheless, the
result also indicated that the capability of hydraulic retention time (HRT) in FWSCW
those systems assist Fe removal.
4.6
Analysis of Variance
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 4.8 through 4.10 shows the
p value when comparing significant differences between control, 50% leachate
concentration and 33% leachate concentration and different HRT used in the
FWSCW to treat landfill leachate.
The details calculation of ANOVA for HRT 3, 6 and 9 day as presented in
Table C1 until C24 in Appendix C.
Table 4.8: Significant differences between control, Cell A and Cell B at HRT 3 days
ANOVA Two Factor Without Replication
95% levels of significance
p value
p value
Parameters
Significant
Significant
p ≥ 0.05
p ≤ 0.05
TSS
0.244
Turbidity
0.571
NH3 N
0.00315
NO3-N
7.31E-05
PO431.69E-05
COD
0.00089
Fe
0.0682
Mn
0.000205
67
Table 4.9: Significant differences between control, Cell A and Cell B at HRT 6 days
ANOVA Two Factor Without Replication
95% levels of significance
p value
p value
Parameters
Significant
Significant
p ≥ 0.05
p ≤ 0.05
TSS
0.7164
Turbidity
0.00768
NH3-N
9.53E-05
NO3-N
0.00189
PO430.3705
COD
0.124
Fe
0.0572
Mn
0.00133
Table 4.10: Significant differences between control, Cell A and Cell B at HRT 9
days
ANOVA Two Factor Without Replication
95% levels of significance
p value
p value
Parameters
Significant
Significant
p ≥ 0.05
p ≤ 0.05
TSS
0.1296
Turbidity
0.5274
NH3-N
0.0045
NO3-N
0.000157
PO430.5102
COD
0.2710
Fe
0.00727
Mn
0.9816
4.7
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% (Cell A), 33% (Cell B) and 100% (control unit). Study done by
Hui (2005) had revealed that 50% leachate concentration will give the highest
removal efficiency in removing NO3-N and Mn.
68
The different hydraulic retention time (HRT) also affects the pollutant
removal in the FWSCW. An overall, the hydraulic retention time of 6 days shows the
greater removal in all parameters except for manganese.
On comparing between control unit and Cell A and B, Cell A and B gives the
highest removal especially at HRT 6 days as shown in Table 4.11. However, both
cells show the removal more than 80%.
Table 4.11: Percentage removal for three cells at HRT 6 days
Description
NH3-N (%)
NO3-N (%)
PO43- (%)
COD (%)
Mn (%)
Zn (%)
Fe (%)
Turbidity (%)
TSS (%)
Cell A
92.67
84.53
87.07
91.35
89.57
94.96
94.44
100.00
90.00
HRT = 6 day
Cell B Control unit
79.07
26.36
97.81
67.23
97.67
84.04
81.42
93.50
88.14
76.00
90.32
79.33
83.04
41.29
100.00
99.00
90.00
100.00
In a constructed wetland systems, the HRT is one of the major factors
affecting the treatment performance. In general, a too long HRT can result in
stagnant anaerobic conditions whereas shorther HRTs do not provide sufficient time
for the degradation of pollutants.
CHAPTER 5
CONCLUSIONS
5.1
Introduction
Wetlands are, as the word indicates, wet lands, with soils that are morw or
less water saturated, at least periodically. The plants growing in wetlands (often
called wetlands plants or macrophyte) are adapted to growing in water saturated soils
(Brix, 1994).
The quality of landfill leachate is highly dependent upon the stage of
fermentation (age of landfill), waste decomposition, operational procedures and codisposal of industrial wastes.
Lab-scale free water surface constructed wetland systems, employing natural
soil and the yellow burhead (Limnocharis flava), were used to evaluate the landfill
leachate effluent. Several aspects were investigated during this experiment; water
quality parameters (TSS and turbidity) were monitored, and pollutant (NH3, NO3, P,
Fe, and Mn) removal efficiencies were evaluated.
The wetland system was proven effective in pollutants removal in leachate.
Wetland of 33% leachate concentration showed high removal efficiency especially at
70
hydraulic retention time (HRT) 6 days. During the experiment, there about 50% of
the Limnocharic flava were harvest and about 70% of Limnocharis flava were
planted each time to allow for the FWSCW beds to maintain treatment efficiencies.
According to Mbuligwe (2005), the plant harvesting could be done in the wetland to
promote active growth of the plants, avoid mosquito proliferation and to improve the
efficiency of the treatment performance.
In this study, the different HRT are used to evaluate the efficiencies of
FWSCW in removal of pollutants with different leachate concentration. However,
the laboratory results shows that the removal efficiencies for 50% leachate
concentration and 33% leaachate concentration not much different. Both cells shows
the removal more than 80% pollutant removal.
The FWSCW were effective in treating the leachate wastewater, resulting in a
treated effluent suitable for reuse in agriculture or discharge to nearby environment
since the the effluent from FWSCW does not exceed the limit of Standard B
Environmental Quality Act.
Better removal efficiencies were obtained for all parameters in Cell B (33%
leachate concentration) especially at HRT 6 days. Therefore, the FWSCW system is
suitable for tertiary landfill leachate treatment. It could be concluded that higher
leachate concentration was more efficient in removing pollutants from leachate due
to the presence of microorganisms for biodegaradation (Stottmeister et al., 2003).
5.2
Recommendations
For future research, there are more extensive studies could be carried out in
order to understand more clearly the processes/mechanisms that happen in
constructed wetland. There are some recommendations for future research:
71
i) A better understanding of the nitrogen removal and nitrogen
transformations occurring in free water surface flow constructed wetlands
systems is necessary and this could ensure a better removal of ammonia
nitrogen and nitrate in the system.
ii) A better understanding and control of the incoming raw landfill leachate
is necessary and this could give useful information during operating the
system.
iii) Use other types of plant such as reeds and bulrushes to determine the
performance and removal efficiency of the constructed wetlands systems.
iv) The use of specialized media other than the media in this study to
improved the porosity and penetration of plant root and avoids clogging
from occurring.
v) Longer period of the test is necessary to determine the fullest capacity of
the free water surface flow constructed wetlands in terms of pollutant
removal.
5.3
Conclusions
Constructed wetlands are getting much attention nowadays as their potential
to provide an effective, low-cost, natural method of removing pollutants from
wastewater are recognized. Biotic component of wetlands especially the vegetation
affects water conditions through many mechanisms physically, chemically and
biologically. There are many unpredictable long-range effects that may develop as
constructed wetlands evolved.
Removal efficiency of the FWSCW in this study did show an effective
performance as predicted. Presence of Limnocharis flava and the second cultivation
of the selected plant did increase the ability of the free water surface flow
72
constructed wetlands to decrease the level of organic matters and increase removal of
nutrients as the analyses was made.
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). The p value are observed when
comparing significant differences between control, 50% leachate concentration and
33% leachate concentration and different HRT used in the FWSCW to treat landfill
leachate.
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APPENDICES
85
APPENDIX A
Standard B under Environmental Quality
(Sewage and Industrial Effluent) Regulations 1979
THIRD SCHEDULE
ENVIRONMENTAL QUALITY (SEWAGE AND INDUSTRIAL EFFLUENTS)
REGULATIONS 1979
[REGULATIONS 8(1), 8(2), 8(3)]
PARAMETER LIMITS OF EFFLUENTS OF STANDARDS A AND B
____________________________________________________________________
Parameter
Unit
Standard
A
B
______________________________________________________________
(1)
(2)
(3)
(4)
(i)
Temperature
40
40
(ii)
pH value 60-9.0
5.5-9.0
(iii)
BOO at 20’C
mg/l
20
50
(iv)
COD
mg/l
50
100
(v)
Suspended Solids
mg/l
50
100
(vi)
Mercury
mg/l
0.005
0.05
(vii)
Cadmium
mg/l
0.01
0.02
(viii)
Chromium, Hexavalent
mg/l
0.05
0.05
(ix)
Arsenic
mg/l
0.05
0.10
(x)
Cyanide
mg/l
0.05
0.10
(xi)
Lead
mg/l
0.10
0.5
(xii)
Chromium, Trivalent
mg/l
0.20
1 .0
(xiii)
Copper
mg/l
0.20
1.0
(xiv)
Manganese
mg/l
0.20
1.0
(xv)
Nickel
mg/l
0.20
1.0
(xvi)
Tin
mg/l
0.20
1.0
(xvii) Zinc
mg/l
1 .0
1 .0
(xviii) Boron
mg/l
1 .0
4.0
(xix)
Iron (Fe)
mg/l
1.0
5.0
(xx)
Phenol
mg/l
0.00
1.0
(xxi)
Free Chlorine
mg/l
1.0
2.0
(xxii) Suiphide
mg/l
0.50
0.50
(xxiii) Oil and Grease
mg/l
Not Detected
10.0
_________________________________________________________________________
86
APPENDIX B
Laboratory Analysis
Table B1: Pre-treated Leachate (Landfill) and influent for Cell A and B
Parameter
Pre-treated
Leachate (Landfill)
Influent 50%
leachate
concentration
(Cell A)
Influent 33%
leachate
concentration
(Cell B)
6.00
10.20
4.00
4.0
4.0
2.5
69.68
70.55
52.70
2.00
0.42
66.95
55.00
4.25
1.15
0.19
27.98
15.30
3.31
1.10
0.21
446.00
286.00
266
0.43
0.22
0.07
Physical
Turbidity
TSS
Nutrients
NH3-N
NO3-N
P
Mn
Fe
Organic Matters
COD
Heavy Metals
Zn
All units in mg/l except turbidity in FAU (Formazin Attenuation Units) is equivalent to NTU
87
APPENDIX B
Laboratory Analysis
Table B1: Influent and effluent quality at HRT 3 day for Cell A
HRT = 3 day
Dilution = 50% leachate, 50% water
Soil : sand = 1: 1
Parameter
NH3-N (inf), mg/l
NH3-N (eff), mg/l
NH3-N (% removal)
NO3-N (inf), mg/l
NO3-N (eff), mg/l
NO3-N (%removal)
PO43- (inf), mg/l
PO43- (eff), mg/l
PO43- (%removal)
COD (inf), mg/l
COD (eff), mg/l
COD (%removal)
Mn (inf), mg/l
Mn (eff), mg/l
Mn (%removal)
Zn (inf), mg/l
Zn (eff), mg/l
Zn (%removal)
Fe (inf), mg/l
Fe (eff), mg/l
Fe (%removal)
Turbidity (inf), FAU
Turbidity (eff), FAU
Turbidity (%removal)
3
66.95
53.99
19.36
55.00
35.76
34.98
4.25
2.63
38.24
286
256
10.49
1.15
0.15
86.70
0.32
0.16
28.13
0.29
0.08
55.08
4.00
2.00
50
6
66.84
35.58
46.77
54.94
15.40
71.97
4.05
1.90
53.09
292
216
26.03
1.28
0.52
54.78
0.28
0.01
97.77
0.19
0.07
62.03
4.00
2.00
50
9
67.95
20.85
69.32
55.48
16.09
70.99
3.27
1.83
44.19
288
154
46.60
2.15
0.20
82.61
0.21
0.02
92.86
0.29
0.04
76.47
4.00
1.00
75
FAU (Formazin Attenuation Units) is equivalent to NTU
12
66.95
19.45
70.96
54.62
12.97
76.25
3.19
1.55
51.41
276
119
56.88
2.16
0.20
82.61
0.22
0.02
89.29
0.16
0.07
60.96
4.00
1.00
75
15
66.35
12.85
80.63
54.53
9.34
82.88
4.38
1.09
75.11
279
93
66.67
1.15
0.15
86.96
0.32
0.04
84.38
0.20
0.05
74.87
4.00
1.00
75
88
APPENDIX B
Laboratory Analysis
Table B2: Influent and effluent quality at HRT 6 day for Cell A
HRT = 6 day
Dilution = 50% leachate, 50% water
Soil : sand = 1: 1
Parameter
NH3-N (inf), mg/l
NH3-N (eff), mg/l
NH3-N (% removal)
NO3-N (inf), mg/l
NO3-N (eff), mg/l
NO3-N (%removal)
PO43- (inf), mg/l
PO43- (eff), mg/l
PO43- (%removal)
COD (inf), mg/l
COD (eff), mg/l
COD (%removal)
Mn (inf), mg/l
Mn (eff), mg/l
Mn (%removal)
Zn (inf), mg/l
Zn (eff), mg/l
Zn (%removal)
Fe (inf), mg/l
Fe (eff), mg/l
Fe (%removal)
Turbidity (inf), FAU
Turbidity (eff), FAU
Turbidity (%removal)
6
66.94
25.58
61.79
55.00
15.40
72.00
4.98
0.90
81.94
286
216
24.48
1.15
0.52
54.78
0.22
0.01
97.77
0.19
0.07
62.03
4.00
1.87
50
12
67.30
17.45
74.08
56.00
12.97
76.84
4.85
1.05
78.36
297
105
64.65
2.15
0.20
82.61
1.22
0.02
89.29
0.29
0.07
60.96
4.00
1.00
75
18
67.94
15.78
76.78
55.83
11.88
78.72
4.72
1.22
74.15
296
98
66.89
2.33
0.10
91.30
0.42
0.03
87.28
0.28
0.00
97.86
4.00
0.00
100
FAU (Formazin Attenuation Units) is equivalent to NTU
24
66.71
9.90
85.16
56.73
13.23
76.68
4.82
0.55
88.59
285
64
77.54
1.85
0.13
89.13
0.72
0.04
84.02
0.18
0.03
82.03
4.00
0.00
100
30
66.95
4.91
92.67
55.00
8.51
84.53
4.95
0.64
87.07
289
25
91.35
2.83
0.12
89.57
0.22
0.01
94.96
0.18
0.01
94.44
4.00
0.00
100
89
APPENDIX B
Laboratory Analysis
Table B3: Influent and effluent quality at HRT 9 day for Cell A
HRT = 9 day
Dilution = 50% leachate, 50% water
Soil : sand = 1: 1
Parameter
NH3-N (inf), mg/l
NH3-N (eff), mg/l
NH3-N (% removal)
NO3-N (inf), mg/l
NO3-N (eff), mg/l
NO3-N (%removal)
PO43- (inf), mg/l
PO43- (eff), mg/l
PO43- (%removal)
COD (inf), mg/l
COD (eff), mg/l
COD (%removal)
Mn (inf), mg/l
Mn (eff), mg/l
Mn (%removal)
Zn (inf), mg/l
Zn (eff), mg/l
Zn (%removal)
Fe (inf), mg/l
Fe (eff), mg/l
Fe (%removal)
Turbidity (inf), FAU
Turbidity (eff), FAU
Turbidity (%removal)
9
66.95
20.85
68.86
55.00
16.09
70.74
4.25
1.83
57.06
286
154
46.22
1.15
0.20
82.61
0.22
0.02
92.86
0.19
0.04
76.47
4.00
1.00
75
18
67.95
15.78
76.79
56.89
18.88
66.81
4.38
1.22
72.15
227
135
40.53
1.25
0.10
92.00
0.22
0.03
87.28
0.29
0.00
98.61
4.00
0.00
100
27
65.97
8.87
86.55
56.37
10.40
81.54
4.67
1.89
59.53
278
75
73.02
1.38
0.12
91.23
0.24
0.02
90.46
0.23
0.02
90.80
4.00
0.00
100
FAU (Formazin Attenuation Units) is equivalent to NTU
36
66.73
17.66
73.53
55.92
11.65
79.16
3.21
1.57
51.09
255
65
74.51
1.15
0.15
86.96
0.21
0.03
84.63
0.18
0.05
72.30
4.00
0.00
100
45
66.15
16.034
75.76
55.173
16.356
70.36
3.69
0.345
90.65
248
55
77.82
1.15
0.12
89.57
0.24
0.03
86.29
0.17
0.05
69.64
4.00
0.00
100
90
APPENDIX B
Laboratory Analysis
Table B4: Influent and effluent quality at HRT 3 day for Cell B
HRT = 3 day
Dilution = 33% leachate, 67% water
Soil : sand = 1: 1
Parameter
NH3-N (inf), mg/l
NH3-N (eff), mg/l
NH3-N (%removal)
NO3-N (inf), mg/l
NO3-N (eff), mg/l
NO3-N (%removal)
PO43- (inf), mg/l
PO43- (eff), mg/l
PO43- (%removal)
COD (inf), mg/l
COD (eff), mg/l
COD (%removal)
Mn (inf), mg/l
Mn (eff), mg/l
Mn (%removal)
Zn (inf), mg/l
Zn (eff), mg/l
Zn (%removal)
Fe (inf), mg/l
Fe (eff), mg/l
Fe (%removal)
Turbidity (inf), FAU
Turbidity (eff), FAU
Turbidity (%removal)
3
27.98
4.86
82.63
15.30
13.50
11.76
3.31
1.84
44.41
266
203
23.68
1.10
0.40
63.64
0.07
0.05
35.62
0.21
0.14
34.15
4.00
2.00
50
6
27.96
7.20
74.24
15.28
11.20
26.70
3.29
1.25
62.13
258
144
44.19
1.08
0.40
62.96
0.07
0.06
17.81
0.21
0.15
29.27
4.00
2.00
50
9
27.88
8.00
71.30
15.20
9.20
39.47
3.21
0.74
77.10
263
127
51.71
1.00
0.20
80.00
0.07
0.02
70.59
0.21
0.05
76.10
4.00
1.00
75
FAU (Formazin Attenuation Units) is equivalent to NTU
12
27.89
5.08
81.80
15.19
6.20
59.18
3.20
0.65
79.69
268
98
63.43
1.10
0.20
81.82
0.07
0.05
25.76
0.21
0.02
92.20
4.00
0.00
100
15
27.83
4.70
83.11
15.15
4.10
72.94
3.16
0.38
88.07
265
60
77.36
1.10
0.10
90.91
0.06
0.05
19.13
0.21
0.02
91.71
4.00
0.00
100
91
APPENDIX B
Laboratory Analysis
Table B5: Influent and effluent quality at HRT 6 day for Cell B
HRT = 6 day
Dilution = 33% leachate, 67% water
Soil : sand = 1: 1
Parameter
NH3-N (inf), mg/l
NH3-N (eff), mg/l
NH3-N (%removal)
NO3-N (inf), mg/l
NO3-N (eff), mg/l
NO3-N (%removal)
PO43- (inf), mg/l
PO43- (eff), mg/l
PO43- (%removal)
COD (inf), mg/l
COD (eff), mg/l
COD (%removal)
Mn (inf), mg/l
Mn (eff), mg/l
Mn (%removal)
Zn (inf), mg/l
Zn (eff), mg/l
Zn (%removal)
Fe (inf), mg/l
Fe (eff), mg/l
Fe (%removal)
Turbidity (inf), FAU
Turbidity (eff), FAU
Turbidity (%removal)
6
28.98
7.20
75.15
15.30
8.20
46.41
3.31
0.95
71.42
266
144
45.86
1.10
0.40
63.64
0.17
0.06
65.32
0.41
0.15
64.20
4.00
2.00
50
12
27.84
5.08
81.77
15.10
6.20
58.94
3.11
0.65
79.10
293
98
66.55
1.10
0.20
81.82
0.17
0.05
71.68
0.32
0.13
59.46
4.00
0.50
87.5
18
30.78
8.08
73.76
14.37
1.70
88.17
2.61
0.72
72.34
257
62.00
75.88
0.95
0.20
78.95
0.07
0.02
67.12
0.51
0.11
78.02
4.00
0.00
100
FAU (Formazin Attenuation Units) is equivalent to NTU
24
28.93
6.30
78.22
14.81
2.40
83.79
3.44
0.62
82.10
268
96.00
64.18
1.06
0.20
81.13
0.14
0.03
76.22
0.28
0.07
75.27
4.00
0.00
100
30
31.58
6.61
79.07
15.92
0.35
97.81
2.92
0.07
97.67
296
55.00
81.42
1.18
0.14
88.14
0.09
0.01
90.32
0.23
0.04
83.04
4.00
0.00
100
92
APPENDIX B
Laboratory Analysis
Table B6: Influent and effluent quality at HRT 9 day for Cell B
HRT = 9 day
Dilution = 33% leachate, 67% water
Soil : sand = 1: 1
Parameter
NH3-N (inf), mg/l
NH3-N (eff), mg/l
NH3-N (%removal)
NO3-N (inf), mg/l
NO3-N (eff), mg/l
NO3-N (%removal)
PO43- (inf), mg/l
PO43- (eff), mg/l
PO43- (%removal)
COD (inf), mg/l
COD (eff), mg/l
COD (%removal)
Mn (inf), mg/l
Mn (eff), mg/l
Mn (%removal)
Zn (inf), mg/l
Zn (eff), mg/l
Zn (%removal)
Fe (inf), mg/l
Fe (eff), mg/l
Fe (%removal)
Turbidity (inf), FAU
Turbidity (eff), FAU
Turbidity (%removal)
9
30.98
8.00
74.17
20.30
9.20
54.68
3.31
0.74
77.79
289
127
56.06
1.12
0.20
82.14
0.07
0.02
72.60
0.21
0.05
76.10
4.00
1.00
75
18
29.98
6.08
79.73
19.30
13.70
29.02
3.31
1.22
63.08
272
62.00
77.21
1.10
0.20
81.82
0.05
0.02
54.72
0.24
0.05
78.30
4.00
0.00
100
27
29.98
5.94
80.18
16.73
13.96
16.56
4.72
1.18
75.00
278
187
32.73
1.24
0.36
70.97
0.07
0.03
53.42
0.24
0.05
78.30
4.00
0.00
100
FAU (Formazin Attenuation Units) is equivalent to NTU
36
32.98
6.943
78.94
16.39
8.18
50.09
4.13
0.982
76.22
291
105
63.92
1.12
0.37
66.96
0.06
0.02
62.50
0.24
0.05
78.30
4.00
0.00
100
45
27.98
7.05
74.80
15.30
6.90
54.89
3.31
1.46
55.95
266
95.00
64.29
1.10
0.20
81.82
0.07
0.04
42.47
0.31
0.06
79.34
4.00
0.00
100
93
APPENDIX B
Laboratory Analysis
Table B7: Influent and effluent quality at HRT 3 day for control unit
HRT = 3 day
Dilution = 100% leachate
Soil : sand = 1: 1
Parameter
NH3-N (inf), mg/l
NH3-N (eff), mg/l
NH3-N (%removal)
NO3-N (inf), mg/l
NO3-N (eff), mg/l
NO3-N (%removal)
PO43- (inf), mg/l
PO43- (eff), mg/l
PO43- (%removal)
COD (inf), mg/l
COD (eff), mg/l
COD (%removal)
Mn (inf), mg/l
Mn (eff), mg/l
Mn (%removal)
Zn (inf), mg/l
Zn (eff), mg/l
Zn (%removal)
Fe (inf), mg/l
Fe (eff), mg/l
Fe (%removal)
Turbidity (inf), FAU
Turbidity (eff), FAU
Turbidity (%removal)
3
69.68
60.34
13.40
70.55
68.92
2.30
52.70
47.92
9.07
446.00
105
76.46
2.00
1.53
23.50
0.43
0.07
84.88
0.42
0.37
11.90
6.00
4.80
20
6
70.48
55.21
21.66
69.45
65.92
5.08
51.62
45.63
11.60
450.00
85
81.04
2.00
1.23
38.50
0.43
0.08
82.56
0.42
0.29
30.95
6.00
3.90
35
9
68.38
58.94
13.80
69.52
58.62
15.67
53.84
45.77
14.99
435.00
91
79.08
2.00
1.38
31.00
0.43
0.06
87.21
0.42
0.32
22.86
6.00
0.08
98.67
FAU (Formazin Attenuation Units) is equivalent to NTU
12
68.62
28.34
58.70
70.54
53.37
24.34
53.94
41.80
22.50
428.50
86
80.02
2.00
1.55
22.50
0.43
0.04
91.40
0.42
0.18
57.14
6.00
0.08
98.67
15
69.67
39.14
43.82
70.55
50.92
27.82
53.80
41.33
23.18
403.00
40
89.98
2.00
1.03
48.50
0.43
0.08
80.93
0.42
0.10
76.19
6.00
0.08
98.67
94
APPENDIX B
Laboratory Analysis
Table B8: Influent and effluent quality at HRT 6 day for control unit
HRT = 6 day
Dilution = 100% leachate
Soil : sand = 1: 1
Parameter
NH3-N (inf), mg/l
NH3-N (eff), mg/l
NH3-N (%removal)
NO3-N (inf), mg/l
NO3-N (eff), mg/l
NO3-N (%removal)
PO43- (inf), mg/l
PO43- (eff), mg/l
PO43- (%removal)
COD (inf), mg/l
COD (eff), mg/l
COD (%removal)
Mn (inf), mg/l
Mn (eff), mg/l
Mn (%removal)
Zn (inf), mg/l
Zn (eff), mg/l
Zn (%removal)
Fe (inf), mg/l
Fe (eff), mg/l
Fe (%removal)
Turbidity (inf), FAU
Turbidity (eff), FAU
Turbidity (%removal)
6
70.48
55.21
21.66
79.45
65.92
17.02
51.62
45.63
11.60
450.00
185
58.82
2.00
1.23
38.50
0.43
0.08
82.56
0.48
0.28
41.67
6.00
4.00
33.33
12
69.48
60.73
12.59
75.45
55.32
26.68
49.22
15.83
67.84
465.89
155
66.66
2.33
0.76
67.38
0.33
0.05
84.85
0.32
0.17
46.88
6.50
3.90
40.00
18
69.43
58.73
15.41
78.45
55.03
29.85
49.62
10.76
78.32
460.31
95
79.29
2.26
0.83
63.27
0.37
0.08
77.57
0.33
0.20
39.39
5.50
1.90
65.45
FAU (Formazin Attenuation Units) is equivalent to NTU
24
69.78
54.12
22.43
78.33
30.92
60.52
48.24
5.93
87.71
463.55
64
86.23
2.06
0.50
75.73
0.35
0.06
84.29
0.27
0.06
79.26
5.00
1.00
80.00
30
69.18
50.94
26.36
78.24
25.64
67.23
48.43
7.73
84.04
461.53
30
93.50
2.00
0.48
76.00
0.39
0.08
79.33
0.31
0.05
83.23
5.00
0.05
99.00
95
APPENDIX B
Laboratory Analysis
Table B9: Influent and effluent quality at HRT 9 day for control unit
HRT = 9 day
Dilution = 100% leachate
Soil : sand = 1: 1
Parameter
NH3-N (inf), mg/l
NH3-N (eff), mg/l
NH3-N (%removal)
NO3-N (inf), mg/l
NO3-N (eff), mg/l
NO3-N (%removal)
PO43- (inf), mg/l
PO43- (eff), mg/l
PO43- (%removal)
COD (inf), mg/l
COD (eff), mg/l
COD (%removal)
Mn (inf), mg/l
Mn (eff), mg/l
Mn (%removal)
Zn (inf), mg/l
Zn (eff), mg/l
Zn (%removal)
Fe (inf), mg/l
Fe (eff), mg/l
Fe (%removal)
Turbidity (inf), FAU
Turbidity (eff), FAU
Turbidity (%removal)
9
71.38
58.94
17.42
69.52
60.93
12.35
55.33
40.62
26.59
459
91
80.17
2.00
1.57
21.50
0.43
0.06
87.21
0.42
0.32
22.86
6.00
0.10
98.33
18
70.68
48.92
30.78
68.57
60.41
11.90
54.88
30.13
45.10
447
174.00
61.07
2.59
0.64
75.29
0.23
0.06
76.09
0.42
0.22
46.67
6.10
0.06
99.02
27
70.50
47.52
32.59
68.33
55.82
18.31
54.27
19.53
64.01
443
150
66.14
2.19
0.13
94.06
0.15
0.06
63.33
0.42
0.22
46.67
6.18
0.06
99.03
FAU (Formazin Attenuation Units) is equivalent to NTU
36
69.98
27.49
60.72
67.93
50.77
25.26
54.75
15.92
70.92
444
85
80.86
2.20
0.17
92.27
0.10
0.06
45.00
0.42
0.12
70.48
7.40
0.05
99.38
45
68.38
20.61
69.86
67.14
50.14
25.32
55.25
12.32
77.70
400
50.40
87.40
2.20
0.10
95.45
0.10
0.06
45.00
0.42
0.12
70.48
7.10
0.05
99.35
96
APPENDIX C
Analysis of Variance
Table C1: Result of ANOVA for TSSat HRT 3 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
3
80.000
85.000
85.000
6
80.000
90.000
90.000
9
80.000
90.000
90.000
12
80.000
90.000
90.000
15
99.930
90.000
90.000
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
5
5
5
Sum
419.93
445
445
Average Variance
83.986 79.44098
89
5
89
5
3
3
3
3
3
250
260
260
260
279.93
83.33333
86.66667
86.66667
86.66667
93.31
ANOVA
Source of
Variation
Rows
Columns
Error
SS
83.80065
159.1613
198.6026
Total
441.5646
df
8.333333
33.33333
33.33333
33.33333
32.8683
MS
F
P-value
F crit
2 41.90033 1.687806 0.244603 4.45897
4 39.79033 1.602812 0.26395 3.837853
8 24.82533
14
97
APPENDIX C
Analysis of Variance
Table C2: Result of ANOVA for Turbidity at HRT 3 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
3
20.00
50.00
50.00
6
35.00
50.00
50.00
9
98.67
75.00
75.00
12
98.67
75.00
100.00
98.67
75.00
100.00
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Count
5
5
5
Column 1
Column 2
Column 3
Column 4
Column 5
ANOVA
Source of
Variation
Sum
351
325
375
Average
70.2 1547.533
65
187.5
75
625
3
120
40
300
3
135
45
75
3 248.6667 82.88889 186.7037
3 273.6667 91.22222 197.8148
3 273.6667 91.22222 197.8148
SS
Rows
Columns
Error
250.1333
7775.6
1664.533
Total
9690.267
df
MS
F
P-value
F crit
2 125.0667 0.601089 0.571212 4.45897
4
1943.9 9.342679 0.004151 3.837853
8 208.0667
14
98
APPENDIX C
Analysis of Variance
Table C3: Result of ANOVA for NH3-N at HRT 3 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
3
13.398
19.356
82.627
6
21.660
46.767
74.244
9
13.799
69.316
71.300
12
58.697
70.956
81.800
15
43.821
80.633
83.109
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Count
Column 1
Column 2
Column 3
Column 4
Column 5
ANOVA
Source of
Variation
Sum
Average Variance
5 151.3749 30.27499 405.4545
5 287.0281 57.40561 606.4759
5 393.0811 78.61622 29.76093
3
3
3
3
3
SS
Rows
Columns
Error
5871.392
2344.554
1822.211
Total
10038.16
115.3815
142.6717
154.415
211.4533
207.5626
38.4605
47.55723
51.47167
70.48442
69.18753
1471.908
691.7415
1065.413
133.6059
484.1329
df
MS
F
P-value
F crit
2 2935.696 12.8885 0.003147 4.45897
4 586.1385 2.573306 0.118899 3.837853
8 227.7764
14
99
APPENDIX C
Analysis of Variance
Table C4: Result of ANOVA for NO3-N at HRT 3 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
3
2.303
34.978
11.765
6
5.076
71.969
26.702
9
15.673
70.993
39.474
12
24.341
76.254
59.184
15
27.824
82.881
72.937
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 75.21737 15.04347 127.9607
5 337.0759 67.41517 350.7549
5 210.0609 42.01219 601.7478
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
6859.03
3623.013
698.8411
Total
11180.88
49.04638
103.747
126.1397
159.7786
183.6425
df
16.34879 282.6692
34.58232 1165.263
42.04657 770.048
53.25953 700.0698
61.21417 860.885
MS
F
P-value
F crit
2 3429.515 39.25945 7.31E-05 4.45897
4 905.7532 10.36863 0.002976 3.837853
8 87.35514
14
100
APPENDIX C
Analysis of Variance
Table C5: Result of ANOVA for PO43- at HRT 3 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
3
9.070
38.235
44.411
6
11.604
53.086
62.128
9
14.990
44.190
77.103
12
22.503
51.411
79.688
15
23.178
75.114
88.070
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 81.34534 16.26907 40.45527
5 262.0361 52.40723 196.358
5 351.3985 70.27969 296.7986
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
7570.899
1615.961
518.4869
Total
9705.346
91.71638
126.8181
136.2823
153.6009
186.3622
df
30.57213
42.2727
45.42743
51.20031
62.12074
356.2838
725.8617
965.653
817.5562
1179.338
MS
F
P-value
F crit
2 3785.449 58.40764 1.69E-05 4.45897
4 403.9902 6.233372 0.014026 3.837853
8 64.81086
14
101
APPENDIX C
Analysis of Variance
Table C6: Result of ANOVA for COD at HRT 3 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
3
76.457
10.490
23.684
6
81.040
26.027
44.186
9
79.080
46.597
51.711
12
80.016
56.884
63.433
15
89.975
66.667
77.358
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 406.5694 81.31388 26.33761
5 206.6649 41.33297 524.2311
5 260.3726 52.07452 409.1651
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
4281.323
2945.127
893.8077
Total
8120.258
110.6311
151.2534
177.3887
200.3332
234.0003
df
36.87704
50.41781
59.12957
66.77774
78.00011
1218.479
785.7228
305.0663
142.1669
136.1305
MS
F
P-value
F crit
2 2140.661 19.15993 0.00089 4.45897
4 736.2819 6.59007 0.011956 3.837853
8 111.726
14
102
APPENDIX C
Analysis of Variance
Table C7: Result of ANOVA for Mn at HRT 3 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
3
23.500
86.696
63.636
6
38.500
54.783
62.963
9
31.000
82.609
80.000
12
22.500
82.609
81.818
15
48.500
86.957
90.909
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5
164
32.8
118.7
5 393.6522 78.73043 183.6733
5 379.3266 75.86532 148.7163
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
6620.726
903.9264
900.4324
Total
8425.085
173.832
156.2456
193.6087
186.9269
226.3656
df
57.94401
52.08186
64.53623
62.30896
75.4552
1022.725
155.0797
845.2105
1188.721
548.843
MS
F
P-value
F crit
2 3310.363 29.41132 0.000205 4.45897
4 225.9816 2.007761 0.186292 3.837853
8 112.554
14
103
APPENDIX C
Analysis of Variance
Table C8: Result of ANOVA for Fe at HRT 3 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
3
11.905
55.08
34.146
6
30.952
62.03
29.268
9
22.857
76.47
76.098
12
57.143
60.96
92.195
15
76.190
74.87
91.707
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Count
Column 1
Column 2
Column 3
Column 4
Column 5
ANOVA
Source of
Variation
Sum
Average Variance
5 199.0476 39.80952 692.1315
5 329.4118 65.88235 87.13432
5 323.4146 64.68293 951.0529
3
3
3
3
3
SS
Rows
Columns
Error
2166.529
4656.725
2264.55
Total
9087.804
101.1313
122.2528
175.4253
210.3005
242.7641
33.71044
40.75092
58.4751
70.10018
80.92137
466.1724
340.3751
951.5138
369.7873
87.69088
df
MS
F
P-value
F crit
2 1083.264 3.826859 0.068217 4.45897
4 1164.181 4.112715 0.042302 3.837853
8 283.0688
14
104
APPENDIX C
Analysis of Variance
Table C9: Result of ANOVA for TSS at HRT 6 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
6
80.000
85.000
85.000
12
85.000
90.000
90.000
18
90.000
90.000
90.000
24
100.000
90.000
90.000
5
5
5
Sum
455
445
445
Average
91
89
89
Variance
80
5
5
3
3
3
3
3
250
265
270
280
280
83.33333
88.33333
90
93.33333
93.33333
8.333333
8.333333
0
33.33333
33.33333
30
100.000
90.000
90.000
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
ANOVA
Source of
Variation
Rows
Columns
Error
SS
13.33333
206.6667
153.3333
Total
373.3333
df
MS
F
P-value
F crit
2 6.666667 0.347826 0.716393 4.45897
4 51.66667 2.695652 0.108483 3.837853
8 19.16667
14
105
APPENDIX C
Analysis of Variance
Table C10: Result of ANOVA for Turbidity at HRT 6 days
Time (day)
Control (%)
Cell A
Cell B
6
33.33
50.00
50.00
12
40.00
75.00
87.50
18
65.45
100.00
100.00
24
80.00
100.00
100.00
30
99.00
100.00
100.00
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 317.7879 63.55758 749.6454
5
425
85
500
5
437.5
87.5
468.75
3 133.3333 44.44444 92.59259
3
202.5
67.5
606.25
3 265.4545 88.48485 397.7961
3
280 93.33333 133.3333
3
299 99.66667 0.333333
ANOVA
Source of
Variation
Rows
Columns
Error
SS
1732.112
6145.083
728.4987
Total
8605.694
df
MS
F
P-value
F crit
2 866.056 9.510584 0.007683 4.45897
4 1536.271 16.87054 0.000577 3.837853
8 91.06234
14
106
APPENDIX C
Analysis of Variance
Table C11: Result of ANOVA for NH3-N at HRT 6 days
Time (day)
Control (%)
Cell A
Cell B
6
21.660
61.787
75.151
12
12.587
74.079
81.768
18
15.405
76.781
73.762
24
22.432
85.160
78.220
30
26.356
92.672
79.066
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 98.44098 19.6882 31.16248
5 390.4782 78.09564 136.5552
5 387.9658 77.59316 10.15704
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
11274.45
347.867
363.6318
Total
11985.94
158.5978
168.4336
165.9481
185.8113
198.0942
df
52.86594
56.14452
55.31604
61.93709
66.0314
775.0018
1437.706
1196.94
1182.525
1226.866
MS
F
P-value
F crit
2 5637.223 124.0205 9.53E-07 4.45897
4 86.96676 1.913293 0.201655 3.837853
8 45.45397
14
107
APPENDIX C
Analysis of Variance
Table C12: Result of ANOVA for NO3-N at HRT 6 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
6
17.024
72.000
46.405
12
26.675
76.839
58.940
18
29.849
78.716
88.170
24
60.523
76.681
83.795
30
67.227
84.535
97.808
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 201.2987 40.25974 492.6644
5 388.7707 77.75415 20.49963
5 375.1184 75.02367 461.6435
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
4369.694
2748.458
1150.772
Total
8268.924
135.4296
162.4547
196.7349
220.999
249.5696
df
45.1432
54.15158
65.57829
73.66632
83.18988
756.7749
646.3119
979.7828
142.2032
235.1601
MS
F
P-value
F crit
2 2184.847 15.18874 0.001888 4.45897
4 687.1145 4.776721 0.028977 3.837853
8 143.8465
14
108
APPENDIX C
Analysis of Variance
Table C13: Result of ANOVA for PO43- at HRT 6 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
6
11.604
81.942
71.420
12
67.838
78.359
79.100
18
78.315
74.153
72.337
24
87.706
88.589
82.099
30
84.039
87.071
97.671
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 329.503 65.9006 977.6224
5 410.1141 82.02282 35.9917
5 402.6269 80.52537 112.1111
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
793.4205
2192.23
2310.671
Total
5296.322
164.9662
225.2974
224.8049
258.3941
268.7814
df
54.98873
75.09913
74.93497
86.13136
89.59381
1439.354
39.67699
9.393355
12.39092
51.23071
MS
F
P-value
F crit
2 396.7103 1.37349 0.307054 4.45897
4 548.0576 1.897484 0.204372 3.837853
8 288.8338
14
109
APPENDIX C
Analysis of Variance
Table C14: Result of ANOVA for COD at HRT 6 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
6
58.818
24.476
45.865
12
66.662
64.646
66.553
18
79.292
66.892
75.875
24
86.232
77.536
64.179
30
93.496
91.349
81.419
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 384.4995 76.89991 200.0045
5 324.8993 64.97987 624.3453
5 333.8911 66.77821 185.3234
3 129.158 43.05265
3 197.861 65.95367
3 222.0596 74.01986
3 227.9474 75.98247
3 266.2639 88.75465
ANOVA
Source of
Variation
Rows
Columns
Error
SS
412.9501
3435.653
603.0391
Total
4451.643
df
300.7781
1.284556
41.02451
123.3963
41.5111
MS
F
P-value
F crit
2 206.475 2.739127 0.124115 4.45897
4 858.9133 11.39446 0.002188 3.837853
8 75.37989
14
110
APPENDIX C
Analysis of Variance
Table C15: Result of ANOVA for Mn at HRT 6 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
6
38.500
54.783
63.636
12
67.382
82.609
81.818
18
63.274
91.304
78.947
24
75.728
89.130
81.132
30
76.000
89.565
88.136
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 320.8845 64.17689 235.9019
5 407.3913 81.47826 233.6106
5 393.6696 78.73392 82.90926
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
864.6261
2005.52
204.1673
Total
3074.313
156.919
231.8089
233.5261
245.9907
253.7008
df
52.30632
77.26962
77.84202
81.99689
84.56694
162.5582
73.48034
197.3367
45.4662
55.55526
MS
F
P-value
F crit
2 432.3131 16.93956 0.001332 4.45897
4 501.3799 19.64584 0.000337 3.837853
8 25.52091
14
111
APPENDIX C
Analysis of Variance
Table C16: Result of ANOVA for Fe at HRT 6 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
6
41.667
62.03
64.198
12
46.875
60.96
59.464
18
39.394
97.86
78.020
24
79.259
82.03
75.273
30
83.226
94.44
83.043
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 290.4207 58.08413 456.2477
5 397.3262 79.46524 303.8634
5 359.9972 71.99944 96.7363
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
1177.543
2299.88
1127.509
Total
4604.933
167.8963
167.3012
215.2747
236.5641
260.7078
df
55.96543
55.76708
71.75823
78.85469
86.9026
154.5132
59.86349
884.0036
11.54499
42.60073
MS
F
P-value
F crit
2 588.7714 4.177501 0.057248 4.45897
4 574.9701 4.079577 0.043148 3.837853
8 140.9387
14
112
APPENDIX C
Analysis of Variance
Table C17: Result of ANOVA for TSS at HRT 9 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
9
95.00
95.00
95.00
18
95.00
90.00
90.00
27
100.00
95.00
95.00
36
100.00
100.00
100.00
Average
98
96
96
Variance
7.5
17.5
17.5
45
100.00
100.00
100.00
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
5
5
5
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
13.33333
150
20
Total
183.3333
Sum
490
480
480
285
95
0
275 91.66667 8.333333
290 96.66667 8.333333
300
100
0
300
100
0
df
MS
F
P-value
F crit
2 6.666667 2.666667
0.1296 4.45897
4
37.5
15 0.000868 3.837853
8
2.5
14
113
APPENDIX C
Analysis of Variance
Table C18: Result of ANOVA for Turbidity at HRT 9 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
9
98.33
75.00
75.00
18
99.02
100.00
100.00
27
99.03
100.00
100.00
36
99.38
100.00
100.00
45
99.35
100.00
100.00
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 495.1093 99.02187 0.177581
5
475
95
125
5
475
95
125
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
53.9181
689.8546
310.8557
Total
1054.628
248.3333
299.0164
299.0291
299.3784
299.3521
df
82.77778
99.67213
99.67638
99.79279
99.78404
181.4815
0.322494
0.314199
0.128804
0.139919
MS
F
P-value
F crit
2 26.95905 0.693802 0.527401 4.45897
4 172.4637 4.438424 0.034986 3.837853
8 38.85696
14
114
APPENDIX C
Analysis of Variance
Table C19: Result of ANOVA for NH3-N at HRT 9 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
9
17.422
68.857
74.173
18
30.782
76.785
79.733
27
32.593
86.554
80.183
36
60.717
73.529
78.945
45
69.857
75.761
74.799
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 211.3714 42.27429 486.104
5 381.4872 76.29745 42.18772
5 387.8329 77.56658 8.154833
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
4007.886
747.363
1398.423
Total
6153.672
160.4521
187.2999
199.3309
213.1912
220.4175
df
53.48405 982.4131
62.43331 753.539
66.44362 869.552
71.06372 87.61744
73.47249 10.03312
MS
F
P-value
F crit
2 2003.943 11.46402 0.004477 4.45897
4 186.8408 1.068865 0.431701 3.837853
8 174.8029
14
115
APPENDIX C
Analysis of Variance
Table C20: Result of ANOVA for NO3-N at HRT 9 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
9
12.350
70.740
54.680
18
11.900
66.808
29.016
27
18.308
81.543
16.557
36
25.261
79.161
50.092
45
25.320
70.355
54.889
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 93.13984 18.62797 43.39165
5 368.6076 73.72152 39.6984
5 205.2328 41.04657 300.9416
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
7675.91
569.1628
966.9639
Total
9212.037
137.7697
107.7237
116.4087
154.5141
150.5642
df
45.92322
35.90789
38.80289
51.50471
50.18806
909.8607
789.3402
1370.828
727.8004
523.6075
MS
F
P-value
F crit
2 3837.955 31.75263 0.000157 4.45897
4 142.2907 1.177216 0.389715 3.837853
8 120.8705
14
116
APPENDIX C
Analysis of Variance
Table C21: Result of ANOVA for PO43- at HRT 9 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
9
26.586
57.059
77.795
18
45.098
72.146
63.082
27
64.013
59.529
75.000
36
70.922
51.090
76.223
45
77.701
90.650
55.952
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 284.3213 56.86427 434.5339
5 330.4746 66.09492 247.3725
5 348.0506 69.61011 92.23459
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
433.3634
731.2691
2365.295
Total
3529.927
161.4393
180.3261
198.5422
198.2355
224.3034
df
53.81311 663.4818
60.1087 189.5233
66.18072 63.36208
66.07849 175.507
74.76781 307.455
MS
F
P-value
F crit
2 216.6817 0.73287 0.510201 4.45897
4 182.8173 0.618332 0.661997 3.837853
8 295.6619
14
117
APPENDIX C
Analysis of Variance
Table C22: Result of ANOVA for COD at HRT 9 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
9
80.174
46.224
56.055
18
61.074
40.529
77.206
27
66.140
73.022
32.734
36
80.856
74.510
63.918
45
87.400
77.823
64.286
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 375.6439 75.12879 121.795
5 312.1064 62.42128 309.3365
5 294.1983 58.83966 270.5075
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
732.7407
908.0833
1898.473
Total
3539.297
182.4534
178.8083
171.8954
219.2832
229.5083
df
60.81781
59.60278
57.29845
73.0944
76.50276
305.1701
337.9281
464.4053
73.22929
134.874
MS
F
P-value
F crit
2 366.3703 1.543853 0.271015 4.45897
4 227.0208 0.956646 0.480352 3.837853
8 237.3091
14
118
APPENDIX C
Analysis of Variance
Table C23: Result of ANOVA for Mn at HRT 9 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
9
21.500
76.098
82.143
18
75.290
78.298
81.818
27
94.064
78.298
70.968
36
92.273
78.298
66.964
45
95.455
79.344
81.818
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
ANOVA
Source of
Variation
Rows
Columns
Error
Total
Count
Sum
Average Variance
5 378.5808 75.71615 984.9846
5 390.3354 78.06709 1.417499
5 383.7112 76.74225 52.41256
3
3
3
3
3
SS
13.89159
1165.594
2989.665
4169.15
179.7404 59.91347 1115.833
235.4056 78.46854 10.67752
243.3295 81.10985 139.2888
237.5349 79.1783 160.7107
256.617
85.539 75.26865
df
MS
F
P-value
F crit
2 6.945794 0.018586 0.981628 4.45897
4 291.3984 0.779749 0.568659 3.837853
8 373.7081
14
119
APPENDIX C
Analysis of Variance
Table C24: Result of ANOVA for Fe at HRT 9 days
Time (day)
Control (%)
Cell A (%)
Cell B (%)
9
22.857
76.47
82.609
18
46.667
98.61
92.000
27
46.667
90.80
91.232
36
70.476
72.30
86.957
45
70.476
69.64
89.565
Anova: Two-Factor Without Replication
SUMMARY
Row 1
Row 2
Row 3
Column 1
Column 2
Column 3
Column 4
Column 5
Count
Sum
Average Variance
5 257.1429 51.42857 396.8254
5 407.8127 81.56253 157.4408
5 442.3623 88.47246 14.48347
3
3
3
3
3
ANOVA
Source of
Variation
Rows
Columns
Error
SS
3880.088
666.8394
1608.159
Total
6155.086
181.9364
237.2729
228.6986
229.7278
229.6821
df
60.64548
79.09098
76.23285
76.57593
76.56071
1080.388
799.4128
655.666
81.64458
127.0124
MS
F
P-value
F crit
2 1940.044 9.651005 0.007372 4.45897
4 166.7099 0.82932 0.542431 3.837853
8 201.0199
14
APPENDIX D
Figures Of The Whole Experiment
Plate D1: Constructed wetlands made of concrete,
divided by 3 cells, build in front of the environmental
laboratory
Sand Gravel
Medium Gravel
Large Gravel
Plate D2: Each cell filled with large gravel,
medium gravel and sand
120
APPENDIX D
Figures Of The Whole Experiment
Plate D3: After all the filling complete
Plate D4: All three cells wash out with tap water to clean
all the debris that trapped in the CWs
121
APPENDIX D
Figures Of The Whole Experiment
Plate D5: Domestic wastewater taken from oxidation
pond in UTM
Plate D6: Domestic wastewater then fed into the
CWs to acclimatize the plant as long as 1 week
122
APPENDIX D
123
Figures Of The Whole Experiment
(a)
(c)
(b)
(d)
Plate D7: (a) Secondary Treatment of Landfill Leachate (b) About 23 bottles
samples is required for this study (c) Method of collected landfill leachate
(d) Method of collected landfill leachate
APPENDIX D
Figures Of The Whole Experiment
Plate D8: Dilution of landfill leachate before poured into the CWs
Plate D9: Leave the CWs with leachate for 3-5 day for plant to
adopt a new environment
124
125
APPENDIX D
Figures Of The Whole Experiment
Plate D10: During experiment
From
landfill
Before
treatment
After
treatment
Plate D11: Before and after treatment by using a
FWSCW