Chemosphere 50 (2003) 121–129
www.elsevier.com/locate/chemosphere
Treatment of domestic wastewater by an
hydroponic NFT system
Nathalie Vaillant a,*, Fabien Monnet a, Huguette Sallanon b,
Alain Coudret b, Adnane Hitmi a
a
b
Laboratoire de Biotechnologies, Environnement-Sant
e, Universit
e dÕAuvergne, IUT de Clermont-Ferrand,
100 rue de lÕEgalit
e, F-15000 Aurillac, France
UMR A408. Qualit
e et s
ecurit
e des aliments dÕorigine v
eg
etale, Universit
e dÕAvignon et Pays de Vaucluse,
74 rue Louis-Pasteur, F-84029 Avignon, France
Received 10 October 2001; received in revised form 5 July 2002; accepted 5 July 2002
Abstract
The objectives in this work were to investigate a conceptual layout for an inexpensive and simple system that would
treat primary municipal wastewater to discharge standards. A commercial hydroponic system was adapted for this
study and the wastewater was used to irrigate Datura innoxia plants. Influent and effluent samples were collected once a
month for six months and analysed to determine the various parameters relating to the water quality. The legal discharge levels for total suspended, biochemical oxygen demand and chemical oxygen demand were reached with the
plant system after 24 h of wastewater treatment. Total nitrogen and total phosphorus reduction were also obtained.
NHþ
4 –N was reduced by 93% with nitrification proving to be the predominant removal process. Significant nitrification
occurred when the BOD5 level dropped 45 mg/l. Similar results were obtained for six months although the sewage
composition varied widely. D. innoxia develops and uses the wastewater as the unique nutritive source.
Ó 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Wastewater treatment; Nutrient film technique; Plant production; Organic loading; Pollutant removal; Nitrogen and
phosphorus removal
1. Introduction
The collection and treatment of wastewater in low
population density areas is problematic. Decentralised
sewage treatment is usually inevitable for economic
reasons, but the currently available technologies for the
wastewater treatment from single houses, dwellings and
small communities remain in many aspects unsatisfactory (Rababah and Ashbolt, 2000). The increase in
wastewater production in the rural areas leads to environment pollution. Nitrification–denitrification and
*
Corresponding author. Tel.: +33-4-71-45-57-55; fax: +33-471-45-57-59.
E-mail address: adnane.hitmi@u-clermont1.fr (N. Vaillant).
phosphate precipitation are classical methods to fight
against the eutrophication of aquatic ecosystems (Brix,
1999). These treatments are expensive and produce huge
quantities of sludge that it will no longer be possible to
tip as landfill after the year 2005 (European Directive 91/
271/CEE of 21 May 1991). There is an increasing need
for developing low cost and energy saving wastewater
treatment systems suited to rural areas. Recently, considerable attention has been directed toward wastewater
treatment processes using wetlands consisting of bed
filters usually planted with emergent plants because of
low cost and ease of operation (Cooper, 1999). The use of
constructed wetlands/reed bed treatment systems has
gradually developed over the past 20 years (Philippi et al.,
1999; Huang et al., 2000). Compared with conventional wastewater treatment systems, they are relatively
0045-6535/03/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved.
PII: S 0 0 4 5 - 6 5 3 5 ( 0 2 ) 0 0 3 7 1 - 5
122
N. Vaillant et al. / Chemosphere 50 (2003) 121–129
Nomenclature
UPSII
BOD5
COD
DW
Fv =Fm
photochimical efficiency of PSII
biochemical oxygen demand
chemical oxygen demand
dry weight
ratio of variable fluorescence over maximal
fluorescence
inexpensive to construct and maintain and can provide
effective and reliable wastewater treatment (Hammer,
1989).
Domestic wastewater has constituents mainly derived
from organic matter and contains most of the required
nutrients for plant growth, generally in appropriate ratio
(Ayaz and Saygin, 1996). Macrophytes ranging from
duckweeds (Culley and Epps, 1973), through water hyacinth (Gopal, 1987), to cattails, reeds and sedges
(Kadlec and Knight, 1996) are generally planted in
wetlands. Studies conducted on the removal of total
phosphorus (TP) and total nitrogen (TN) (Abe and
Ozaki, 1998; Ikeda and Tan, 1998; Drizo et al., 2000)
showed a very wide range of treatment effectiveness.
These plants enhance biodiversity, but they are of a
limited value, and they are not useful for rural communities apart from purification. Jewell (1994) has
combined anaerobic treatment of primary sewage with a
specialized hydroponic (water as a growth medium)
secondary or tertiary treatment system that yields biomass. Accordingly we investigated the possibility of introducing valuable commercial species such as D. innoxia
into the treatment system. We developed treatment of
sewage with a terrestrial species (D. innoxia) using the
nutrient film technique (NFT) developed initially by
Cooper (1976). We have reviewed some of the studies
carried out to evaluate the effectiveness of D. innoxia
plants for sewage purification.
D. innoxia is a perennial plant, of a herbaceous species, belonging to Solanaceae family. They are distributed in warm regions of the world (Drake et al., 1996).
This plant is commonly found in the tailings of abandoned mines, in highly dry places, such as river washes
and slopes. The leaves of D. innoxia were an important
source of tropane alkaloids: atropine, hyoscyamine,
scopolamine. The aerial parts contain little scopolamine,
the major alkaloid is hyoscyamine. The economic importance of hyoscyamine and scopolamine relies on their
medicinal applications. Both alkaloids are used as parasympathicolitics because of their ability to suppress the
activity of the parasympathic nerve system. Until now,
plant material remains the sole source for these compounds and they are of commercial interest to the
pharmaceutical industry (Griffin and Lin, 2000).
NFT
PCA
PSII
SS
TN
TP
nutrient film technique
principal component analysis
photosystem II
total suspended solids
total nitrogen
total phosphorus
2. Materials and methods
2.1. The laboratory pilot plants
The laboratory pilot plants consisted of PVC (polyvinyl chloride) tanks 4 m long, 0.15 m wide and 0.10 m
deep (Fig. 1). The purification system used NFT soilless
culture (Cooper, 1976) with permanent recirculation of
30 l of wastewater, regulated by an electric pump with a
flow rate of 10 l/min. The experiment lasted six months
(July–December); this period includes three seasons and
thus different qualities of wastewater. The sewage comes
from a community of 980 people without industry; it
was representative of a rural community. The raw effluent was obtained weekly and stored at 4 °C. It was
placed in contact with the plants without pre-processing
and the 30 l of wastewater were renewed every 72 h.
D. innoxia plants were developed initially in individual pots containing a 50/50 mixture of vermiculite/
compost. After six months of culture, they were transferred to a hydroponic system. These plants presented
an average shoot length of 65 5 cm and a fresh mass of
75 5 g. The plants grew bare-rooted in 3 mm solution
flowing by gravity. Three channels were used: one with
25 plants supplied with wastewater (planted channel),
one with 25 plants supplied with a nutritive solution of
Lesaint and Co€ıc (1983) (control plant channel) and one
plant-free channel supplied with wastewater (unplanted
channel) to know the role of plants. These experiments
Fig. 1. System of wastewater treatment: horizontal flow system
with plants (D. innoxia) in the ditch (P is the pump).
N. Vaillant et al. / Chemosphere 50 (2003) 121–129
were performed in a glass house with a controlled temperature at 25 3 °C/15 3 °C (day/night) and with a
natural photoperiod.
2.2. Measurement of water quality parameters
The experiment lasted six months (July–December);
wastewater quality was followed once a month during
a 72 h recirculation cycle. In July, wastewater samples
were analysed after 0, 12, 24, 48 and 72 h of treatment
and in August–December, wastewater samples were
analysed once a month after 0 and 48 h of treatment.
The various samples necessary for the analysis of the
physical, chemical and biological parameters were taken
in compliance with international standards for water
analysis (ISO 5667). Five replicates were made for each
measurement. All the parameters commonly used to
assess the performance and treatment capacities of such
systems were examined (standard method number follows each parameter in brackets).
The pH was measured using a glass electrode with a
WTW pH 320 pH-meter (NF T90-008) and dissolved
oxygen with a WTW OXI 320 portable oximeter (ISO
5814). Total suspended solids (SS) were determined after
filtration under vacuum with 47 mm diameter glass fibre
filters (Durieux, France), followed by drying to constant
weight at 105 °C (NF EN 872). The chemical oxygen
demand (COD), expressed in mg/l O2 consumed, was
measured according to standard ISO 6060. The biochemical oxygen demand (BOD5 ) was determined after
five days in the dark in a thermostated incubator set at
20 °C, by measuring the oxygen concentration, expressed in mg/l (ISO 5815).
TN in water was measured by spectrophotometric
assay, at 324 nm (Genesys 5, Spectronic) after potassium
peroxodisulphate digestion at 120 °C, 45 min, 100 KPa
(ISO 7890-1). TP concentration in water was measured
according to standard ISO 6878 by spectrophotometric
assay at 880 nm using ascorbic acid and after potassium
peroxodisulphate digestion, 120 °C, 30 min, 100 KPa.
The concentration of NHþ
4 –N was determined by spectrophotometric assay at 655 nm according to standard
ISO 7150-1.
2
The concentrations of NO
3 –N, NO2 –N and SO4
were determined by capillary electrophoresis using a
Beckman P/ACE System 5510 equipped with a diode
array detector. The capillary (Beckman) was 60 cm long
(54 cm effective length) with 75 mm internal diameter.
All measurements were made in anionic mode (Romano
and Krol, 1993). The capillary was thermostated at
25 °C, and a constant voltage of 20 kV, with an initial
ramp of 0.17 min, was applied during analysis. Sample
injections were made with pressure mode for 30 s, 3.45
kPa. The indirect UV detection was at 254 nm with a
bandwidth of 1 nm. The carrier buffer was a chromate
electrolyte solution, 4.7 mM sodium chromate (Fisher
123
scientific), 4 mM OFM-OH (Waters), 10 mM CHES
(Sigma), 0.1 mM calcium gluconate (Sigma), pH 9. The
detection of NHþ
4 was performed at 214 nm and with a
constant voltage of 25 kV. The running electrolyte
contained 65 mM 2-hydroxy isobutyric acid (Aldrich),
50 mM 4-methyl benzyl amine (Fluka) and 20 mM 18crown-6-ether (Sigma).
2.3. Statistical analysis
Principal component analysis (PCA) was performed
using STATLAB software on all parameters for the
control system of ditches with plants (10 variables, five
samples at five different times, i.e., 25 individual items).
This factorial analysis helps understand how depollution
in plant systems occurs by evaluating the links between
the different parameters and any similarities between the
different sampling times (Thioulouse et al., 1991). All
data were analysed using the Mann and Whitney test
at the 0.05 probability level (Dagnelie, 1970).
2.4. Growth measurements and water relations
At the beginning and at the end of the experimentation, six plants per treatment were harvested, separated into shoot and root parts, and their fresh weights
were determined. The dry weights (DW) were obtained
by drying the plant at 85 °C to constant weight. The
growth rate is determined by the ratio: DW at the end of
the experimentation/DW at the beginning of the experimentation.
2.5. Chlorophyll a fluorescence measurements
A wide range of laboratory studies have established
that chlorophyll a fluorescence is a sensitive and early
indicator of damage to photosynthesis and to the plant
physiology resulting from environmental stresses (Kooten and Snel, 1990; Lanaras et al., 1994). It provides
information on the inhibition or damage occurring in
the transfer of the electrons from photosystem II (PSII)
photochimical efficiency of PSII (UPSII) on photochemical quantum yield, and is a sensitive indicator of
photoinhibition. In addition the measurement of chlorophyll a fluorescence is both non-destructive and noninvasive. Fluorescence parameters were measured on
intact leaves of twenty plants of D. innoxia, with a pulse
amplitude modulation portable fluorescence monitoring
system (PAM FMS, Hansatech Instruments, Norfolk,
UK). The measuring probe of the fluorimeter was placed
in the adaxial side in the central parts of the leaves. The
parameters used to define the yield and quenching
mechanisms of chlorophyll a fluorescence were: DF =
F 0 m, quantum yield of electron flow throughout PSII
UPSII; Fv =Fm , maximal photochemical efficiency of the
124
N. Vaillant et al. / Chemosphere 50 (2003) 121–129
PSII, measured in pre-darkened (for 30 min) leaves
(Maxwell and Johnson, 2000).
3. Results and discussion
Table 1
Total plant biomass, growth rate, shoot/root ratio, ratio of
variable fluorescence over maximal fluorescence (Fv =Fm ) and
UPSII from plant cultivated six months with nutrient solution
and with wastewater. Values are means standard error
(n ¼ 6)
Nutrient
solution
Wastewater
Plant dry weight (g.plant1 )
Growth rate
Shoot dry weight/root dry weight
51.7 3.1
0.91 0.11
3.61 0.39
53.5 5.7
0.97 0.20
3.49 0.32
Fv =Fm
UPSII
0.87 0.04
0.75 0.02
0.86 0.03
0.76 0.01
3.1. Plant behaviour
Virtually every terrestrial plant appears to be able to
grow in some form of hydroponic system (Cooper,
1976). To evaluate plant survival, we used the growth
rate, the shoot/root ratio and the chlorophyll a fluorescence. The transfer of soil-grown Datura plants in hydroponic culture was obtained without plant loss. After
six months, the total plant dry weight and shoot/root
ratio of the plants which grow on wastewater are identical to those of the control plants (Table 1). The chlorophyll a fluorescence of the seedlings of D. innoxia
cultivated on wastewater is not significantly different
from those of seedlings cultivated on a nutritive solution. The growth of plants developed on wastewater was
identical to the control plants.
3.2. Wastewater purification
SS, BOD5 , COD removals: The NFT system with D.
innoxia was very effective in reducing SS, BOD5 and
COD parameters. The concentrations of those parameters decreased exponentially (Fig. 2A, B, C) and may fit
the 1st order kinetics. After 24 h the system has reached
the legal discharge levels (Directive 91/271 of the Euro-
pean Union) and after 48 h its maximal efficiency
is obtained. Similar results were obtained from July
to December although the sewage composition varied
widely (Table 2): SS (37–400 mg/l), BOD5 (64–1100 mg/l),
and COD (187–1650 mg/l). The removal efficiencies observed after 48 h show that the system is stable for six
months although the sewage composition varied widely
(Fig. 3) and reduced SS, BOD5 and COD parameters
respectively, 98%, 91% and 82%.
SS and thus indirectly BOD5 and COD were decreased by filtration and adsorption; the solids trapped
in the root systems were then decomposed and mineralised by bacteria. The NFT system with D. innoxia can
strongly reduce the total organic load without root
system saturation and without sedimentation of the
hydroponic channels.
Fig. 2. Concentration of SS (A), BOD5 (B), COD (C) and total phosphorus (D), with plant system (k) and with the control (O) in July
2000; (– – –) indicates the legal discharge level and ( ) indicates the legal discharge level in eutrophically sensitive areas. Values are
means standard error; n ¼ 5.
N. Vaillant et al. / Chemosphere 50 (2003) 121–129
Table 2
General parameters: characteristics of the inlet (n ¼ 20) and
treatment goals (mg/l), discharge norms (European directive 91/
271)
Wastewater
SS
BOD5
COD
TN
TP
Objectives
Mean
Min
Max
164
179
429
41
9
37
64
188
13
4
400
1100
1650
100
16
35
25
125
15*
2*
*Indicates the legal discharge level in eutrophically sensitive
areas.
Total phosphorus (TP): The data (Fig. 2D) show that
the TP decreased, but it was not completely eliminated
by the system. Fig. 3 shows that when the wastewater is
very charged (TP > 10 mg/l) the system removes one
third of the TP in 48 h. When wastewater is more diluted
(water concentrations decreased significantly due to
autumn rains) the removal is less significant. The average TP removal after 48 h was 38 9%.
Uptake of phosphorus has been reported to occur by
sorption, complexation, precipitation, and assimilation
into microbial and plant biomass (Tanner et al., 1999).
The removal variations observed can be explained by the
fact that phosphorus could be present in various forms
that are not removed or assimilated in the same way
by plants and bacteria. TP sums into orthophosphates
(PO3
4 ), acid-hydrolysable phosphates, organic soluble
phosphates and particulate phosphorus. Acid-hydrolysable phosphates are negligible in sewage (Drizo et al.,
2000). Organic phosphorus is converted by the bacterial
activity into mineral phosphorus that can be assimilated
by the plants. Particulate phosphorus might be removed
by filtration or sorption in the root system.
Nitrogen: TN sums the nitrogen in ammonium
(NHþ
4 ), oxidised forms (Nox ¼ NO2 þ NO3 ) and aggregate and soluble organic forms (Fig. 4A1, B1). The
TN decreased more quickly in the presence of D. innoxia
than in the control ditch (Fig. 3E). The results are
practically the same in other months. Three major nitrogen removal mechanisms have been identified: microbial denitrification (Gersberg et al., 1986) and plant
nitrogen uptake (Breen, 1990; Rogers et al., 1991) and
volatilisation (Sanchez-Monedero et al., 2001). Initially,
the wastewater had a high concentration of TN mainly
composed of NHþ
4 with a very low content of NO2 and
NO
.
After
48
h
treatment,
the
ammonium
concentra3
tions in the effluent were strongly reduced, by approximately 93 12% of D. innoxia and were no longer
measurable after 72 h processing with the plants. The
decrease was slower in the control ditch: at 48 h,
72 19% NHþ
4 was still present in the wastewater.
125
NO
2 concentration values remained very low (Fig.
4A1, B1). The highest content was observed after 48 h of
processing. Parallel to the NHþ
4 decrease we observed
the appearance of NO
3 . As indicated in Fig. 4A2, a
significant proportion of the NHþ
4 removed from the
wastewater was found to be converted by nitrifying
bacteria into NO
2 and NO3 . With the plants, the reþ
moved NH4 was mainly transformed into NO
2 and
NO
3 . However, July–September, significant amounts of
the NHþ
4 removed was not found as NO2 or NO3 . This
þ
quantity of NH4 , which seemed to have disappeared,
was either reduced by other processes such as absorption
by the plants, or by the combined nitrification–denitrification process which has been reported to transform
the NO
2 and NO3 into gaseous N2 in anoxic regions
(Flite III et al., 2001). This process also seems to be
responsible for the NHþ
4 removal in the control.
In nitrogen removal, the pH is a significant parameter. Princic et al. (1998) have shown that the optimal pH
range for NHþ
4 conversion to nitrite is between 5.8 and
8.5 and for nitrification between 6.5 and 8.5. In wetlands, pH values were between 6 and 7 (Martin et al.,
1999; Philippi et al., 1999). In our treatment system, the
pH was constant and the values were between 7 and 8
(data not shown); hence the nitrification was active.
It was noted that the quantity of NHþ
4 removal decreases with time however the percent removal remains
stable. This decrease is to connect with increase of the
wastewater dilution (the initial NHþ
4 concentration decreases, due to increase the rains).
The nitrification process was affected by the BOD5
level of the wastewater because of the competition for
available oxygen between the nitrifying bacteria and the
microorganisms removing BOD5 . Fig. 5 illustrates the
relationship between the NO3 –N and NO2 –N contents
and the BOD5 level of the effluents out of the D. innoxia
treatment (A) and control (B). Significant nitrification
began to take place in the wastewater when the BOD5
was reduced to less than 45 mg/l with the plants. In the
control, NO
2 and NO3 are not formed. Although both
are oxygen-demanding processes; nitrification proceeds
much more slowly than the reaction for BOD5 reduction. Therefore, under a high BOD5 level most of the
available oxygen transported into the root matrix is used
for BOD5 removal. This inhibits the establishment of
a large population of nitrifying bacteria (Gray et al.,
1996). Consequently, significant nitrification cannot
occur until towards the end of carbonaceous oxidation
that removes BOD5 . As the BOD5 drops to a low level,
the available oxygen begins to be used by the nitrifying
bacteria and noticeable nitrification then takes place.
The conversion of ammonium to nitrite and subsequent oxidation of nitrite to nitrate was more marked
with the plant system. The removal of nitrogen is based
on the nitrification/denitrification activity of root-associated bacteria (Farahbakhshazad and Morrison, 1997).
126
N. Vaillant et al. / Chemosphere 50 (2003) 121–129
Fig. 3. Load of inlet wastewater and after 48 h with the plants and with the control for SS (A), BOD5 (B), COD (C), TP (D) and TN
(E). (06/2000–12/2000). (– – –) indicates the legal discharge level and ( ) indicates the legal discharge level in eutrophically sensitive
areas. Values are means standard error; n ¼ 5.
The plant roots with the organic matter provide a large
surface area for microbial growth and allow the biofilm
formation (Gopal, 1999). The system of wastewater recirculation led to water oxygenation. The dissolved oxygen determined in the inflow was generally 0:8 0:2
mg/l (data not shown). Dissolved oxygen concentrations
were approximately 5:8 0:3 mg/l after 48 h, and provide oxygen necessary for the reduction of BOD5 then to
the conversion of ammonium to nitrite and to nitrate. In
comparison, other studies have indicated a low efficiency
of ammonium conversion to nitrite in wetland systems
owing to limited oxygen transfer capability (Cooper,
1999).
After 48 h of plant culture, 30 l of wastewater were
found to reduce to 9 l. This phenomenon is generally reported in many macrophyte systems (Ayaz and
Saygin, 1996; Neralla et al., 2000). To characterise the
evapotranspiration, Ayaz and Saygin (1996) advised to
follow the SO2
4 concentration in treated wastewater. In
our NFT system, the sulphate concentrations increases
after 48 h of treatment of 28 9% with D. innoxia and
remains identical in the control ditch. The concentration
of TN and TP in the effluent was approximately 28%
lower than the influent concentration following 48 h
circulation. The removed mass of these elements was
higher than that reflected by concentration because of
N. Vaillant et al. / Chemosphere 50 (2003) 121–129
127
Fig. 4. Organic N concentration (1) and NHþ
4 –N removal (2) after 48 h in the plant system with D. innoxia (A) and control (B);
(i ¼ inlet and o ¼ outlet).
A PCA of organic burden parameters is represented
in Fig. 6. The first two principal components (axes 1 and
3) account for 77% of inertia. Axis 1 represents most of
the variance of the result (70%) and groups SS, BOD5 ,
COD, TP, TN, NHþ
4 . All these variables are strong and
positively correlated (decrease with treatment time) ex
cept for O2 , NO
2 and NO3 which were inversely correlated (increase), and the pH which did not vary.
Mathematically, it is possible to design a NFT system
treatment that could treat wastewater from communities. The sewage loading rate, in terms of depth of raw
sewage loading onto the hydroponic channels in a 48 h
of treatment is: 2.5 cm per day which is calculated as
follows:
Fig. 5. Effect of BOD5 level on nitrification process in the plant
system with D. innoxia (A) and control (B).
evapotranspiration. Plants growing in the NFT system
used some of the water, which would have resulted in
nutrient being more concentrated. Kadlec (1999) has
shown that the evapotranspiration may have significant
effects and influence treatment efficiency. Thus, we can
assume the mass of TN and TP removed were about
30% higher than that reflected by obtained concentration.
Fig. 6. PCA for the plant system in July 2000. Correlation
circle for parameters considered on first two axes.
128
HLR ¼
N. Vaillant et al. / Chemosphere 50 (2003) 121–129
30 l=48 h m3 =103 l 24 h=d
Channel area ð¼ 4 m 0:15 mÞ
HLR ¼ 0:025 m per day or 2:5 cm=d
If the hydraulic loading rate (HLR) calculated is 2.5 cm/
d, and assuming that the wastewater flow is 150 l per
person per day, the surface area necessary to treat a
commune of 100 people is:
Area ¼
Daily flow rate of wastewater; m3 =d
Hydraulic loading rate; m=d
Area ¼
100 people 150 l=pers-d m3 =1000 l
0:025
¼ 600 m2 ; or 6 m2 of production area per person
For a community of 100 people (150 l of wastewater/
people), the treatment system would need 25 000 plants
and a surface area of 600 m2 . It is suggested that a NFT
system treatment may be economical for rural communities where land is abundant, whereas for larger urban
communities, higher land prices are likely to be render
a NFT system treatment uneconomical, given the very
large number of plants required (about 100 000 plants
for 400 people).
4. Conclusion
The system of wastewater purification with NFT
using D. innoxia made it possible, as early as the first
month of installation and throughout the following six
months, to achieve the permitted levels for discharge,
defined by the European directive 21/05/1991, after 24 h
of processing. During this period the root systems were
not saturated and there was no sedimentation in the
ditch bottom. The wastewater seemed to provide the
necessary elements for growth and a normal physiological activity.
Acknowledgements
The authors gratefully acknowledge the financial
support provided by French state (FNADT).
References
Abe, K., Ozaki, Y., 1998. Comparison of useful terrestrial and
aquatic plant species for removal of nitrogen and phosphorus from domestic wastewater. Soil Sci. Plant Nutr. 44 (4),
599–607.
€ ., 1996. Hydroponic tertiary treatment.
Ayaz, S.C., Saygin, O
Water Res. 5, 1295–1298.
Breen, P.F., 1990. A mass balance method for assessing the
potential of artificial wetlands for wastewater treatment.
Water Res. 24 (6), 689–697.
Brix, H., 1999. How ‘‘green’’ are aquaculture, constructed
wetlands and conventional wastewater treatment system?
Water Sci. Technol. 40 (3), 45–50.
Cooper, A.J.J., 1976. In: Nutrient Film Technique of Growing
Crops. Grower Books, London, p. 181.
Cooper, P., 1999. A review of the design and performance of
vertical-flow and hybrid reed bed treatment system. Water
Sci. Technol. 40 (3), 1–9.
Culley, D.D., Epps, E.P., 1973. Use of duckweeds for waste
treatment and animal feed. J. Water Poll. Cont. Fed. 45,
337–347.
Dagnelie, P., 1970. Theorie et methodes statistiques: applications agronomiques. Les presses agronomiques de Gembloux, Belgique.
Drake, L.R., Lin, S., Rayson, G.D., Jackson, P.J., 1996.
Chemical modification and metal binding studies of Datura
innoxia. Environ. Sci. Technol. 30, 110–114.
Drizo, A., Frost, C.A., Grace, J., Smith, K.A., 2000. Phosphate
and ammonium distribution in a pilot-scale constructed
wetland with horizontal subsurface flow using shale as a
substrate. Water Res. 34 (9), 2483–2490.
Farahbakhshazad, N., Morrison, G.M., 1997. Ammonia removal processes for urine in an upflow macrophyte system.
Environ. Sci. Technol. 31, 3314–3317.
Flite III, O.P., Shannon, R.D., Schnabel, R.R., Parizek, R.R.,
2001. Nitrate removal in a riparian wetland of the appalachian valley and ridge physiographic province. J. Environ.
Qual. 30, 254–261.
Gersberg, R.M., Elkins, B.V., Lyon, S.R., Goldman, C.R.,
1986. Role of aquatic plants in wastewater treatment by
artificial wetlands. Water Res. 20 (3), 363–367.
Gopal, B., 1987. In: Water Hyacinth. Aquatic Plant Studies 1.
Elsevier, Amsterdam, p. 471.
Gopal, B., 1999. Natural and constructed wetlands for wastewater treatment: potentials and problems. Water Sci.
Technol. 40 (3), 25–35.
Gray, K.R., Biddlestone, A.J., Thayanithy, K., Job, G.D.,
Bere, S.S.J., Edwards, J., Sun, G., Cooper, D.J., 1996. Use
of reed bed treatment systems for the removal of BOD and
ammoniacal-nitrogen from agricultural Ôdirty waterÕ. In: 5th
Int. Conf. on Wetland Systems for Water Pollution Control,
Vienna, Austria, 12, pp. 1–8.
Griffin, W.J., Lin, G.D., 2000. Chemotaxonomy and geographical distribution of tropane alkaloids. Phytochemistry 53,
623–637.
Hammer, D.A., 1989. Constructed wetlands for wastewater
treatment. Lewis Publishers, Chelsea, Mich.
Huang, J., Reneau, J.R., Hagedorn, C., 2000. Nitrogen removal
in constructed wetlands employed to treat domestic wastewater. Water Res. 34 (9), 2582–2588.
Ikeda, H., Tan, X., 1998. Urea as an organic nitrogen source for
hydroponically grown tomatoes in comparison with inorganic nitrogen sources. Soil Sci. Plant Nutr. 44 (4), 609–615.
Jewell, W.J., 1994. Resource-Recovery Wastewater Treatment.
For many communities, the challenge of according thorough sewage treatment may be best met by a new technological approach. Am. Sci. 82, 366–375.
Kadlec, R.H., 1999. Chemical, physical and biological cycles in
treatment wetlands. Water Sci. Technol. 40 (3), 37–44.
Kadlec, R., Knight, R.L., 1996. Treatment wetlands. Lewis
Publishers, Boca Raton, FL, USA.
N. Vaillant et al. / Chemosphere 50 (2003) 121–129
Kooten, O.V., Snel, J.F.H., 1990. The use of chlorophyll
fluorescence nomenclature in plant stress physiology. Photosynth. Res. 25, 147–150.
Lanaras, T., Sgardelis, S.P., Pantis, J.D., 1994. Chlorophyll
fluorescence in the dandelion (Taraxascum spp.): a probe for
screening urban pollution. Sci. Total Environ. 149, 61–68.
Lesaint,, C., Co€ıc, Y., 1983. In: Cultures hydroponiques. La
Maison Rustique, Paris, p. 119.
Martin, C.D., Johnson, K.D., Moshiri, G.A., 1999. Performance of a constructed wetland leachate treatment system
at the Chunchula landfill, Mobile county, Alabama. Water
Sci. Technol. 40 (3), 67–74.
Maxwell, K., Johnson, G.N., 2000. Chlorophyll fluorescence––
a pratical guide. J. Exp. Bot. 51 (345), 659–668.
Neralla, S., Weaver, R.W., Lesikar, B.J., Persyn, R.A., 2000.
Improvement of domestic wastewater quality by subsurface
flow constructed wetlands. Bioresource Technol. 75, 19–
25.
Philippi, L.S., Rejane, H.R., Sererino, D.C., Sererino, P.H.,
1999. Domestic effluent treatment through integrated system of septic tank and root zone. Water Sci. Technol. 40 (3),
125–131.
Princic, A., Mahne, I., Megusar, F., Paul, E.A., Tiedje, J.M.,
1998. Effects of the pH and oxygen and ammonium
concentrations on the community structure of nitrifying
129
bacteria from wastewater. Appl. Environ. Microb., 3584–
3590.
Rababah, A.A., Ashbolt, N.J., 2000. Innovative production
treatment hydroponic farm for primary municipal sewage
utilisation. Water Res. 34 (3), 825–834.
Rogers, K.H., Breeen, P.F., Chick, A.J., 1991. Nitrogen
removal in experimental wetland treatment systems: Evidence for the role of aquatic plants. Research J. WPCF. 63
(7), 934–941.
Romano, J., Krol, J., 1993. Capillary ion electrophoresis, an
environmental method for the determination of anions in
water. J. Chromatogr. 640, 403–412.
Sanchez-Monedero, M.A., Roig, A., Paredes, C., Bernal, M.P.,
2001. Nitrogen transformation during organic waste composting by the Rutgers system and its effects on pH, EC and
maturity of the composting mixtures. Bioresource Technol.
78, 301–308.
Tanner, C.C., Sukias, J.P.S., Upsdell, M.P., 1999. Substratum
phosphorus accumulation during maturation of gravel-bed
constructed wetland. Water Sci. Technol. 40 (3), 147–154.
Thioulouse, J., Devillers, J., Chessel, D., Auda, Y., 1991.
Graphical techniques for multidimensional data analysis.
In: Devillers, J., Kercher, W. (Eds.), Applied Multivariata
Analysis in SAR and Environmental Studies. Kluwer
Academic, Dordrecht, pp. 153–205.