comparative performance of water hyacinth ( eichhornia crassipes) and water lettuce (pista...

Zubaidah Ismail1

Siti Zulaikha Othman1

Kim Hing Law1

Abdul Halim Sulaiman2

Roslan Hashim1

1Department of Civil Engineering,Faculty of Engineering, University ofMalaya, Lembah Pantai, KualaLumpur, Malaysia

2Institute of Biological Studies,University of Malaya, Lembah Pantai,Kuala Lumpur, Malaysia

Research Article

Comparative Performance of Water Hyacinth(Eichhornia crassipes) and Water Lettuce (Pistastratiotes) in Preventing Nutrients Build-up inMunicipal Wastewater

Studies on removal of nutrients from domestic wastewater using water hyacinth(Eichhornia crassipes) and water lettuce (Pista stratiotes) were conducted. The plants weregrown in 68 L of wastewater with 21-day retention period in fiber-glass tanks withanother similar tank as control. Eichhornia crassipes performed better than P. stratiotes inreducing the concentrations of nitrate-nitrogen and ortho-phosphates while P. stratiotesperformed better than E. crassipes in reducing the concentrations of ammoniacal-nitrogen (NH4-N) and nitrite-nitrogen. On average, E. crassipes reduced the NH4-Nconcentration by 72%, P. stratiotes reduced the concentration by 83% and theconcentration in the control was reduced by 95%. On average, E. crassipes reducedthe phosphate concentration by 55%, P. stratiotes reduced the concentration by 60% andthe concentration in the control increased by 28%. Algae significantly reduced theconcentration of NH4-N.

Keywords: Aquatic biology; Bioremediation; Nutrients; Plants; Wastewater

Received: May 2, 2012; revised: April 25, 2013; accepted: April 30, 2013

DOI: 10.1002/clen.201200254

: Additional supporting information may be found in the online version of this article at thepublisher’s web-site.

1 Introduction

Aquatic macrophytes including duckweed (Lemna minor), waterhyacinth (Eichhornia crassipes), and water lettuce (Pista stratiotes) havebeen extensively studied as agents in effluents and wastewatertreatment to reduce parameters like total dissolved solids, totalsuspended solids, chemical oxygen demand (COD), five-daysbiochemical oxygen demand (BOD), turbidity, heavy metals,pesticides, chlorides, ammoniacal-nitrogen (NH4-N), nitrate-nitro-gen (NO3-N), ortho-phosphate (PO4-P), total Kjedahl nitrogen, fecalcoliforms, andmosquito larvae. Aquatic plants offer a simple, cheap,energy-efficient method of treating wastewater [1, 2]. It is moreadvantageous to use macrophytes than to use microorganisms oremergent plants because they are much easier to harvest [3]. Theyalso have high reproductive rates and their roots can directly absorbnutrients from the water column compared to the emergent plantswith roots attached on the substrates [4]. In addition, they do notrequire extensive filtration equipment to remove. There is also nosignificant disruption to the water body [5]. Yilmaz and Akbulut [6]

used duckweeds to reduce five-day BOD and COD in wastewater.Duckweed was also used to reduce heavy metals but it was found tobe less effective than E. crassipes [7]. Awuah et al. [8] used duckweed totreat turbidity, BOD, COD, nitrates, nitrites, ammonia, totalphosphorus, fecal coliforms, mosquito larvae, and sludge accumu-lations in wastewater. The potential of duckweed as an agent toremove chlorpyrifos in water has also been investigated underlaboratory greenhouse conditions. The removal rate constant of9.20mgh� 1 was observed [9].The potential of E. crassipes and P. stratiotes to serve as

phytoremediation plants in the cleaning up of metals fromcontaminated water bodies [10–16] were studied by variousresearchers [17–20] to render the water to be acceptable for domesticas well as irrigation purposes. The potential of a shallow pondsystem using E. crassipes along with the microorganisms present inthe bio-film attached to the roots and water column for treatment ofdomestic wastewater in the presence of high total dissolved solidsand heavy metal salts was investigated by el-Gendy, Chattopadhyayet al., and others [21–23]. The potential of E. crassipes roots to removearsenic from spiked drinking water samples was investigated byGovindaswamy et al. [24].Investigation of the potential of E. crassipes to remove a

phosphorus pesticide ethion showed the plant uptake and reductionby plant contributed 69% and reduction by microbes contributed upto 12% to the removal of the pesticide [25]. The potential ofP. stratiotes as an agent to remove chlorpyrifos in water wasinvestigated under laboratory greenhouse conditions. It wasobserved that the removal rate constants for P. stratiotes and

Correspondence: Dr. Z. Ismail, Department of Civil Engineering, Facultyof Engineering, University of Malaya, 50603 Lembah Pantai, KualaLumpur, MalaysiaE-mail: [email protected]

Abbreviations: BOD, biochemical oxygen demand; COD, chemicaloxygen demand; DO, dissolved oxygen; HRAP, high rate algal pond;NH4-N, ammoniacal-nitrogen; NO2-N, nitrite-nitrogen; NO3-N, nitrate-nitrogen; PO4-P, ortho-phosphate

1

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.clean-journal.com Clean – Soil, Air, Water 2014, 42 (9999), 1–11

L. minor were 7.27 and 9.20mgh� 1, respectively [26]. Nesic andJovanovic [27] studied the feasibility of E. crassipes in treatingwastewater with pollutants ranging from suspended materials,BOD, nutrients, organic matter to heavy metals, and pathogens.Eichhornia crassipes and P. stratiotes were also used to treataquaculture wastewater from a fish farm [28]. The parametersstudied included the pH, turbidity, dissolved oxygen (DO), COD,BOD, PO4

3� , NO3� , NO2

� , NH3, and total Kjedahl nitrogen.Considerable percentage reduction was observed in all theparameters treated with the phytoremediators. A design methodol-ogy for wastewater treatment in E. crassipes ponds to develop aperformance equation with two dimensionless groups indicatingthe system capacity for nutrient removal was provided byHermosilloa and Sarquisa [29].A bench-scale continuous-flow wastewater treatment system

comprising three parallel lines using P. stratiotes and algae (naturalcolonization) as treatment agents was set up to determineenvironmental conditions, fecal coliform profiles, and generaltreatment performance. Parameters measured included environ-mental conditions, turbidity, BOD, COD, nitrate, nitrite, ammonia,total phosphorus, fecal coliforms, mosquito larvae, and sludgeaccumulations [8]. Nutrient removal by P. stratiotes was also studiedby Aoi and Hayashi [10]Studies byWang et al. [30] recorded removal of nutrients by plants

in a constructed wetland to be 9.66% of total nitrogen and 49% oftotal phosphorus. Based on past studies, the use of aquaticmacrophytes in sewage and other effluent treatment has beensuggested, particularly for secondary and tertiary treatmentprocesses [31–34].It has been documented that macrophytes are efficient in

removing pollutants and nutrients from effluents and wastewater.Studies have been conducted to examine the effectiveness of eachagent to reduce various parameters. However, not all macrophyteshave been studied and the performance of different agents ondifferent parameters has not been thoroughly investigated.Information on related research in warmer countries like Malaysiahas not been extensive and is still lacking in the literature. Withmore sunlight the rate of photosynthesis is expected to be higher.Some work on E. crassipes and P. stratiotes which are the morecommon macrophytes found in the area to determine theireffectiveness in aquaculture wastewater treatment was conductedby Akinbile and Yusoff [28]. The objectives of the current study are to:(i) Confirm the effectiveness of E. crassipes and P. stratiotes astreatment agents to reduce NH4-N, NO3-N, NO2-N, and PO4-Ps fromwastewater. (ii) Compare the performance of water hyacinth(E. crassipes) and water lettuce (P. stratiotes) as agents to reduceNH4-N, NO3-N, nitrite-nitrogen (NO2-N), and PO4-Ps in wastewater.(iii) Determine the contribution by algae in the reduction of NH4-N,NO3-N, NO2-N, and PO4-Ps in wastewater.

2 Materials and methods

Young plants of E. crassipes were collected from its natural habitatfrom a lake in Kuala Lumpur [3�11012.9200 N; 101�43038.2300 E]. Pistastratiotes was obtained from the plants nursery of the Institute ofBiological Sciences, University of Malaya. The experiments werecarried out in five batches where a series of three tanks was set up foreach batch with one tank each for E. crassipes and P. stratiotes and thethird tank was for control and to observe if there was anycontribution made by algae. Both plants were grown in a concrete

tank with flowing tap water before they were transferred toapproximately 68 L of sewage with 21-days retention period in fiber-glass tanks of 470 L volume. Sewage was taken from the aeratedlagoon at Pantai Operation Plant, IndahWater Konsortium at PantaiDalam, Kuala Lumpur. In order to maintain a consistent amount ofplant material and not to over-crowd the water surface for all thetests, about ten to thirteen E. crassipes plants with approximatelysimilar heights of about 20–40 cm, measured from the tip of stem(below the highest leaf) to above the root section, and eight to tenP. stratiotes plants, measuring about 15–18 cm in width, wereselected for the experiments. After transferring the plants into therespective tanks, they were allowed to acclimatize for one weekbefore the readings were taken. No analyses were conducted duringthe acclimatization period. Dead plants and large debris wereremoved from time to time using a net. No additional sewage wasadded during the experiments. The water was not aerated orcirculated but was periodically topped-up to replace any losses dueto evaporation. It is to be noted that there is a slight difference interms of retention time between the pond conditions where there isaeration and the laboratory conditions where there is no aeration.Readings for water temperature, pH, NH4-N, andNO3-Nwere taken

in situ using a multiprobe DataSonde 4� (Hydrolab, USA). Analysesfor NO2-N and PO4-P were conducted in the laboratory usingspectrophotometry (DR 4000U, Hach, USA) at five days intervals. Dueto the difficulty in differentiating the different possible sources ofnutrients after assimilation no dry-weight analyses were conducted.Total dissolved solids were not recorded in this study. Theexperiments were repeated using new batch of plants and sewagefor each experiment. The results from each batch as well as theaverage results from the five batches were analyzed. For each batchof plants, ANOVAwere employed to find the differences between thetreatment mean and control mean at the end of each week at 5%level of significance. Since the values are expected to be very smallthe equality of variance will be applied. A comparison of the controlmean at the end of each week was also made against the startingmean to observe for any effects due to algae. Build-up of algae andbacteria and DO were monitored. No special care was taken toeliminate algae and bacteria.

3 Results and discussion

3.1 Temperature

Temperature is one of the important physical characteristics and itis a measure of average random energy in a system [35]. Besidesnutrients and space, light is essential for plant growth andproductivity. A high intensity of light is needed to attain anappropriate water and air temperature for macrophytes growthespecially E. crassipes and P. stratiotes. Eichhornia crassipes andP. stratiotes are abundant in Malaysia as the ambient temperatureand light intensity are high all year round except during the rainyseason when they do not bloom. Nonetheless, E. crassipes can alsosurvive in temperate climates, where the ambient air temperatureand light intensity determine the length of the vegetative periodand photosynthetic activity [36].At Indah Water Konsortium, Pantai Dalam sewage treatment

plant, the water temperatures recorded for the five batches were inthe range of 27.3 to 29.4� 0.1�C, which is the optimal range for plantgrowth. However, Fig. 1 shows that during the experimental period,the average of the water temperature in the five batches had

2 Z. Ismail et al.


decreased to 26.3�C as the treatment tanks were not exposed directlyto the sun. The maximum water temperature recorded during theexperiment was 27.5� 0.1�C in batch 1, whilst the minimum watertemperature was 24.8�C in batch 5; both were recorded fromP. stratiotes treatment tank. Urbanc-Ber�ci�c and Gaberš�cik [36] foundin their experiment that the optimum water temperature forE. crassipes growth was 25�C. In batches 2, 4, and 5, the watertemperature in the treatment tank with E. crassipes was highcompared to the control. Water surface was covered by themacrophytes which prevented mixing. Statistically, the downtrendof the water temperature during the experimental period werehighly significant for each month; however, there were nosignificant differences between the temperature in the treatmenttanks except in batch 4 and it showed that water temperature wasnot affected by the difference of vegetation coverage in the tanks asshown by the two-way ANOVA: F(2, 14)¼ 68.614, p< 0.05.At Brokopondo Lake in Paramaribo, Surinam, where the climate is

tropical and humid with dry and rainy season, E. crassipes grows inhigh temperature from 27.4 to 29.3�C [37]. Reddy et al. [38, 39] foundthat weekly averages of maximum daily ambient temperatureduring similar experimental period in Sanford, Florida were 28–34�C and 18–32�C. Similarly with the finding reported by Moorheadet al. [34], the maximum daily ambient air temperatures recordedwas in average of 22�C in winter and 37�C in summer season.Dellarossa et al. [31] conducted a research employing E. crassipes totreat effluent from Kraft pulp mill, and they found that E. crassipesremain active the whole year through as themill generated effluentswith controlled temperature within 26–33�C, in spite of airtemperature was within 8–22�C. Gopal [40] in his research reported

that E. crassipes will die at a temperature >35�C, whereas stems andleaves will be killed at freezing air temperature. However, based onthe Environmental Quality Act 1974 (Sewage and IndustrialEffluents Regulations 1978) [41], 40�C is the maximum temperaturelimit for effluents discharged into the river in Standards A and B.

3.2 pH

pH is the logarithm of the reciprocal of the hydrogen-ion of acompound [42]. It plays an important role in water quality as allaquatic organisms require a certain range of pH to survive.Figure 2 shows that although pH values indicate an increase

pattern in the control and P. stratiotes treatment tanks, there werealso a slight decrease of pH in E. crassipes treatment tanks in eachbatch except in batch 3. The pH changes in the sewage were highlysignificant as shown by two-way ANOVA: F(2, 14)¼ 4.922, p< 0.05. Inbatches 2 and 5, E. crassipes treatment tanks had the lowest pH valuesof 7.15 and 7.20 compared to the P. stratiotes (7.68 and 7.56) andcontrol tanks (7.86 and 7.60). These results were in agreement withthe experiment carried out by Fallowfield et al. [43] who examinedthe pH in the high rate algal pond. They pointed out that algalgrowth also affected the equilibrium of pHwhich caused an increaseof pH due to the removal of Hþ ions in the algal photosynthesis.Moreover, algal assimilation of NO3

– and its subsequent reductionwithin the algal cell to NH4 also increased the pH in the algal controltank. They also found that pH of the algal ponds were slightly higherwhich were in the range of 8.2–9.4.Weeks

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Figure 1. Water temperature in sewage over a duration of four-weeksretention.

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Figure 2. pH in sewage over a duration of four-weeks retention.

Preventing Nutrients Build-up Using Water Hyacinth and Water Lettuce 3


Gopal [40] mentioned in his book that E. crassipes has an optimumgrowth at pH ranging from 6 to 8, and P. stratiotes grows in slightlyacidic water with pH of 6.5–7.2. Moreover, Poi de Neiff et al. [44]investigated that pH of E. crassipes floating meadows varied between6.2 and 7.2. Moorhead et al. [45] found that E. crassipes was able toreduce pH in the diluted effluent approximately 7.5%, whilst pH inundiluted effluents reduced in the range of 8.4–9.3%. On the otherhand, pH reduction in a nutrient medium was only 3.5% with a pHvarying from 7.4 to 7.8 initially. Furthermore, Tripathi andShukla [12] observed that the pH of the effluents varied from 6.45to 7.69 when they were held in the E. crassipes culture. He also notedthat pH increment usually occurred during the day when CO2 in thewater was reduced due to active photosynthetic activity. Theoptimum pH for Nitrosomonas and Nitrobacter is between 7.5 and 8.5;most treatment plants are able to effectively nitrify with a pH of6.5–7.0. Nitrification stops at a pH< 6.0. According to theEnvironmental Quality Act of 1974, the acquirement of pH inthe effluents ranges from 6.0 to 9.0 to meet Standard A, meanwhilethe acquirement of pH ranges from 5.5 to 9.0 to meet Standard B.

3.3 Dissolved oxygen

Oxygen dissolved freely in the water from the atmosphere. It mightalso be added to the water as a by-product of photosyntheticactivities from aquatic plants [46]. The solubility of oxygen in waterdepends on the water temperature, the partial pressure of the gas inthe atmosphere in contact with the water, salinity, and biologicalactivity [42].Domestic sewage which was obtained from IWK Pantai, aerated

lagoon had very low DO. Based on Fig. 3, the DO recorded in situ in

the lagoon was in the range of 1.67–3.32mg L� 1 measured in batches5 and 3, respectively. Similarly, Tripathi and Shukla [12] had alsorecorded very low DO concentrations in Varanasi domestic sewage,which varied from 0.64 to 1.4mg L� 1. It was observed that the DOconcentrations increased for all batches except in batch 4, wherethey dropped dramatically at the end of the experiment. This mightbe due to the dead algae and macrophytes. There was a sharpincrease of DO in all tanks in the first week of the treatment in batch1 with the initial DO at 2.23mg L� 1. However, the amount of DO inthe last week of treatment increased to 3.65mg L� 1 (E. crassipes),4.11mg L� 1 (P. stratiotes), and 4.14mg L� 1 (control) in each tank. Fromthe statistical analyses, the increment of DO was significant for allbatches except in batch 2 as shown by the two-way ANOVA:F(2, 14)¼ 28.314, p< 0.05.In batch 5, DO in the control tank increased from 1.67 to

5.38mg L� 1 compared to those in the E. crassipes and P. stratiotestreatment tanks which were 2.30 and 2.55mg L� 1, respectively.Similarly, in batch 2, toward the end of the experiment, the DOconcentration was higher in the control tank (2.77mg L� 1; initially2.05mg L� 1) than in P. stratiotes tank (2.12mg L� 1). The samephenomenon was observed by Tripathi and Shukla [12], who foundthat DO of sewage treated with E. crassipes was very low, andconsequently they treated the sewage with algae cultures for fivedays to increase the DO concentration through photosyntheticactivity. The low DO concentrations could be attributed to intenseheterotrophic activity within the submerged part of the floatingroots as suggested by Poi de Neiff et al. [44]. However, from theresults, it is obvious that E. crassipes and P. stratiotes increased the DOin the tanks throughout the experiments in the range of 3.6–52%.Although the control tank did not contain any macrophytes, thehigh DO concentration was probably due to the presence of algae.Algae are known as O2 contributor as they carry out photosyntheticactivities and release O2 in the water. It has been shown in manyexperiments that high rate algal ponds (HRAPs) can optimize algalphotosynthetic oxygen production to remediate sewage andwastewater [43]. Sufficient O2 in the water is vital for nitrificationprocess as Nitrosomonas bacteria convert ammonia and ammoniumto nitrite and Nitrobacter convert nitrite to nitrate. The reactions aregenerally coupled and proceed rapidly to the nitrate form; therefore,nitrite levels are usually low.Nitrification occurs only under aerobic conditions at DO levels of�1.0mg L� 1. At DO concentrations <0.5mg L� 1, the growth rate ofthe bacteria is minimal. It is very important to ensure that theconcentration of DO in the effluent is in the right level beforedischarging it into the river. Untreated sewage obviously has majoreffects on the river and marine ecosystem. According to the InterimNational River of Water Quality Standards for Malaysia, DO< 3 and1mgL� 1 are classified in the IV and V class, which means the river isvery polluted; meanwhile, an excellent quality river water shouldhave a minimum of 7mgL� 1 of DO.

3.4 Chlorophyll a

In earlier studies, Dinges [47] had performed an experiment to testE. crassipes specifically on algae removal in the stabilization pondeffluent. As a result, he postulated that a system incorporatingE. crassipes could be designed to remove algae or total suspendedsolids to a particular level. Nakai et al. [48] had also investigated thecontrol of algal growth bymacrophytes and their anti-algal bioactivecompounds that inhibit algal growth. They had also pointed out that

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Figure 3. DO concentrations in sewage over a duration of four-weeksretention.

4 Z. Ismail et al.


macrophytes have an antagonistic relationship with algae, in whichalgae were actually competing with macrophytes for nutrientssupply.In Fig. 4, algal growth which is represented by chlorophyll a

concentration was high in the control tanks for each month.Chlorophyll a mean concentrations show a noticeable increment inbatch 1, from 1.35mg L� 1 recorded in the aerated lagoon andincreased to 46.32mg L� 1 in the third week in the control tank.However, the concentration dropped to 21.17mg L� 1 in the fourthweek of the experiment as it was believed that the algae reached thelag phase when there was no more growth occurring. On thecontrary, chlorophyll a mean concentrations in the E. crassipes andP. stratiotes treatment tanks were very low from the beginning andnot much difference was observed until the end of the experiment.The concentrations were 5.13 and 8.36mg L� 1, respectively, in bothtanks. The results were similar in batches 3 and 5, in which thechlorophyll a concentration increased dramatically in control tanksfrom 1.37 to 37.97mg L� 1 in batch 3 and from 1.59 to 8.66mg L� 1 inbatch 5. Whereas chlorophyll a concentrations did not change inboth macrophytes tanks with 2.59mg L� 1 (E. crassipes) and 3.46mg L� 1

(P. stratiotes) in batch 3 and 2.24mg L� 1 (E. crassipes) and 1.93mg L� 1

(P. stratiotes) in batch 5, respectively.The results were in agreement with another investigation of

sewage bioremediation by algal ponds (HRAPs) conducted byFallowfield et al. [43] where they recorded that chlorophyll aconcentrations were in the range of 0.07 to 7.63mg L� 1. Dinges [47]indicated in his study that there were reductions in chlorophyll acontent in the effluent of stabilization pond from 0.351 to0.028mgL� 1 (93% in reduction) in eight months when the pondwas filled up with E. crassipes culture in the first phase. Whereas in

the second phase, where the effluent was cultured with E. crassipesfor three months, the chlorophyll a was reduced from 0.35 to0.017mgL� 1 (95% in reduction). A low density of phytoplankton orchlorophyll a content of sewage also was recorded (775� 103

individuals L� 1) by Tripathi and Shukla [12] in the E. crassipes culturetank. Nonetheless, they believed it was probably due to the restrictedpenetration of sunlight by E. crassipes coverage that inhibits thegrowth of the algae.Except in batch 5, where the chlorophyll a content fluctuated in

all treatment tanks, the presence of chlorophyll a in the control tankwere highly significant in all batches as shown by two-way ANOVA:F(2, 14)¼ 14.499, p< 0.05. In batch 5, the high chlorophyll aconcentration in the E. crassipes and P. stratiotes treatment tankscould be due to the dying of plants. As those plants started to die,they could have stopped secreting the bioactive chemical com-pounds, which could inhibit the algal growth. Furthermore, thebioactive compounds are biodegradable and their effect on algalgrowth will be reduced with time. Nakai et al. [48] supported themacrophyte-secretion theory and the occurrence of a species-specificreaction. In an experiment where they added extracted bioactivecompounds in the algae culture tank showed that, the algae andbacteria growth increased proportionately with time after a certainperiod. Thus, they concluded that the inhibitory effect issignificantly weakened after 1.5 days and would vanish after 3.7days as the extracted bioactive compound are easily biodegraded.As the bioactive compounds are important to inhibit the algal

growth, many researchers have carried out studies to identify andextract the chemical compounds from the macrophytes. Forinstance, Watanuki et al. [49] and Aliotta et al. [50] had identifiedand extracted phenylpropanoid and a-asarone with 80% methanolfrom P. stratiotes which have the resultant inhibitory effect on thegrowth of Anabaena cylindrica (blue-green algae) and Selenastrumcapricornutum (green algae). These anti-algal bioactive compoundscould affect growth-rate, photosynthesis, respiration, and ultra-structure of the algae. In addition, Saito et al. [51] had identifiedgallic and ellagic acid components of hydrolysable tannins as acidiccompounds which also have the inhibitory effects.

3.5 Enumeration of total bacteria

According to Dinges [52], bacteria are the predominant group inpurification process in the preliminary phase of raw wastewatertreatment. As common bacteria species, for instance, Escherichia coli,Salmonella, fecal streptococci, Vibria cholerae, and Shigella are alreadypresent in the domestic sewage itself, the appropriate and suitableconditions is needed tomaintain the population and their growth inorder to ensure the efficiency of the treatment process.Despite the high rates of bacteria multiplications, Tab. 1 shows

there were noticeable drop of bacteria enumerations at the end ofthe experiment. Bacteria multiplications or colony forming on theplate were high in the sewage treated by E. crassipes and P. stratiotescompared to the untreated sewage. In batch 3, the enumeration oftotal bacteria reduced gradually throughout the experiments in alltreatment tanks. However, the percentages of reductions werehigher in the E. crassipes and P. stratiotes treatment tanks by 79.8%(2.0� 104 colony forming units (CFU)mL� 1) and 68.7% (3.1� 104

CFUmL� 1), respectively, compared to the sewage in the control tankby only 61.6% (3.8� 104 from 9.9� 104 CFUmL� 1). Similarly, in batch4, both macrophytes seem to have reduced the number of totalbacteria up to 94.6% (1.3� 104 CFUmL� 1) in E. crassipes and 82.9%

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Figure 4. Chlorophyll a concentrations in over a duration of four-weeksretention.



(4.1�104 CFUmL� 1) in P. stratiotes treatment tanks from the initialnumber (2.4� 105CFUmL� 1). In contrast, sewage in the control tankcould only reduce up to 81.7% (4.4� 104CFUmL� 1) of total bacteriain the sewage after 21 days retention time. However, the differenceswere not significant in all batches except in batch 1 as shown by thetwo-way ANOVA: F(2, 14)¼ 7.404, p< 0.05 where the total bacteria insewage treated by E. crassipes and P. stratiotes were 8�103 and3.8� 104 CFUmL� 1, respectively. On the other hand, the totalbacteria in the control tank was 2.9� 104 CFUmL� 1 from the initialenumeration (>6.5� 106CFUmL� 1).The results were in line with the findings of Dinges [52], where it

was found that the mean total coliform bacteria was 4.7� 104CFU100mL� 1 in the initial effluent and reduced to 2.0� 103CFU/100mL(95% reduction) when the effluent was withheld in the E. crassipesculture for eightmonths (June 1975 to February 1976). Themaximumtotal coliform bacteria recorded were 2.5� 105CFU/100mL andreduced to 1.9� 104CFU/100mL in the same experiment. He alsofound that total coliform bacteria were reduced up to 92% from1.9� 105 to 1.4� 104 in three months when the effluent was culturedwith E. crassipes. Tripathi and Shukla [12] stated that there was aremarkable drop (99.2%) from 14� 105 to 0.11� 105 cells/100mL oftotal coliformbacteriawhen they cultured the sewagewith E. crassipes(15 days) and algae (five days). They had theorized that nutrients andbacteria reductions processes were seenmore physical than chemicalas E. crassipes removes many constituents of wastes by absorption intoits tissue. During the absorption of water by E. crassipes, colloidalparticles in the sewage continuously impinge on the surface of thehairy roots and become agglomerated after losing their electricalcharges and it may be that agglomeration of colloidal particles in thesewage carries bacteria to the bottom.In an experiment of integrated biological systems using E. crassipes

and fish in “bacteria-algal” treatment conducted by Dinges [47],

it was suggested that the primitive organisms or bacteriacontribute to the improvement of the water quality; despite theexistence of other organisms. The capability of algae in reducingbacteria especially E. coli has also been investigated by Sebastian andNair [53] and they reported that there was a reduction in the influentof 1010–105 E. coli/100mL in the effluent treated by the algae in theHRAPmass culture pond operated in two days residence times. Maraet al. [54] also pointed out that although there were slight increasesin a physicochemical effluent quality, the incorporation ofP. stratiotes in a tertiary maturation pond led to the decrease ofmicrobiological effluent quality. Furthermore, with the submergedroots system, it provides a rich rizosphere and suitable substrate to alarge number of species; for example, bacteria, fungi, protozoa,aquatic worms, and snails. It also allows symbiotic activity as it isvery convenient for them to get nutrients because of the highdetritus accumulation by the macrophytes roots [52].

3.6 Other parameters

Plant composition and temperature play important roles in thenutrient removal efficiency of treatment wetlands, but theinteractions between these variables are not well understood.Picard et al. [55] investigated the seasonal efficiency of wetlandmacrophytes to reduce soil leachate concentrations of total nitrogenand total phosphorus in experimental microcosms. Microcosmsexhibited a typical pattern of seasonal nutrient removal with higherremoval rates in the growing season and lower rates in the wintermonths. They found that in general, planted microcosms out-performed unplanted microcosms.A study on the nutrient removal using the Wolffia arrhiza during

the treatment of laying quails farm effluent was conducted bySuppadit [56]. The relationship between W. arrhiza biomass and

Table 1. Enumeration of total bacteria of each month during four weeks experiments

Month Week Control E. crassipes P. stratiotes

Raw >6.5� 106 >6.5� 106 >6.5� 106

Batch 1 I >6.5� 106 >6.5� 106 >6.5� 106

II 1.46� 105� 41.04 8.5� 104�63.84 1.6� 105�0.00III 2.2� 105� 72.11 1.06� 105� 46.05 1.7� 105�185.55IV 2.9� 104� 12.66 8� 103� 3.06 3.8� 104�13.00Raw >6.5� 106 >6.5� 106 >6.5� 106

Batch 2 I >6.5� 106 1.16� 105� 21.63 1.2� 104�4.58II 1.3� 105� 30.02 2.2� 105�45.74 2.1� 105�76.32III 1.8� 105� 79.03 1.9� 105�143.62 1.3� 105�31.19IV 1.9� 105� 28.84 1.1� 105�31.77 1.6� 105�43.10Raw 9.9� 104� 11.72 9.9� 104�11.72 9.9� 104�11.72

Batch 3 I 2.1� 105� 40.00 2.0� 105�116.62 1.3� 105�46.70II 1.8� 104� 2.31 4.3� 104�6.66 5.3� 104�13.05III 4.1� 104� 7.77 4.6� 104�13.75 3.3� 104�16.26IV 3.8� 104� 1.15 2.0� 104�6.56 3.1� 104�8.74Raw 2.4� 105� 93.04 2.4� 105�93.04 2.4� 105�93.04

Batch 4 I >6.5� 106 1.0� 105�11.15 1.1� 105�69.52II 1.6� 105� 38.18 8.8� 104�10.50 2.4� 105�18.33III 6.0� 104� 32.15 9.7� 104�3.06 6.7� 104�27.79IV 4.4� 104� 14.73 1.3� 104�1.15 4.1� 104�22.81Raw 9.5� 104� 12.70 9.5� 104�12.70 9.5� 104�12.70

Batch 5 I 2.1� 105� 58.97 5.9� 104�10.79 1.3� 104�7.21II 1.61� 105� 18.90 6.8� 104�14.42 7.6� 104�100.53III 8.4� 104� 31.43 6.5� 104�50.69 6.7� 104�7.09IV 7.4� 104� 41.05 3.9� 104�2.08 4.8� 104�5.51

Data expressed as means� standard deviations of triplicate.

6 Z. Ismail et al.


treatment time, the change in water qualities, and nitrogen-balance(N-balance) were evaluated. The results showed that a biomass of 12 gofW. arrhiza/L effluent and a treatment period of 30 days were foundto provide the best conditions forW. arrhiza’s growth and the qualityof the treated effluent in terms of biological oxygen demand,suspended solids, total phosphorus, nitrate, total ammonia nitro-gen, and total Kjeldahl nitrogen. The pH and salinity were similar foreach level of biomass.

3.7 Nutrient contents in sewage

3.7.1 Ammonia-nitrogen reduction

Figure5 shows theconcentrationofammonia-nitrogen in sewageovera retention period of four weeks and the overall average for the fivebatches. The figure shows that the initial sewage had an averageconcentration of 27.6mgL� 1 (NH4-N). There were significant reduc-tions in NH4-N for most of the exposures. The average concentrationsafter the first week were 17.7mgL� 1 (36% reduction) for E. crassipes,16.1mgL� 1 (432% reduction) for P. stratiotes and 18.7mgL� 1 (32%reduction) for the control. The concentrations after the fourth weekwere 7.8mgL� 1 (56% at the end of the first week) for E. crassipes,9.8mgL� 1 (70% at the end of the first week) and 1.4mgL� 1 (99% at theend of the first week) for the control. The lowest concentrations wererecorded early during the experiments and then remained aboutconstant until the fourth week. This was especially noticeable in thecase of the control tanks. The rate of ammonia-nitrogen uptake byE. crassipes for the first three weeks on average was 10.25mg/week, therate of similar uptake by P. stratiotes was 11.7mg/week and thecorresponding figure for the control was 12.1mg/week. Similarpatterns were observed for each batch. NH4-N could have beenremoved through assimilation by algae. Some could also have beenlost through ammonia volatilization [37]. It is believed that in the

control tanks, algae have grown based on the greenish color of thesewage. They have consumed the NH4-Nmore than the cases for boththe plants. It was noted that the NH4-N concentration decreasedgradually in the first week of exposure from the initial averageconcentration of 27.6mgL� 1 and most of the reductions reached thelowest concentration in the second week. The concentration thenremained almost constant until the fourth week. However, untreatedwater had a higher removal efficiency of NH4-N (99%) compared to thesewage treated with E. crassipes with 91.1% removal and 95.7% whentreated with P. stratiotes. This was probably due to the consumption byalgaewhich have grown in the tanks. It showed that algae used up theNH4-N more efficiently compared to the plants. These findings are inagreement with the findings of Lau et al. [57] who studied the effect ofalgal density onnutrient removal. They observed that the reductionofNH4-Nwas>90% in tendays. They indicated that the presence of algaewas important in enhancing NH3 stripping, even though inwastewater the NH3 stripping mechanism occurs naturally to reducethe NH4-N. McCarthy et al. [58] also observed that phytoplankton oralgae prefer to use nitrogen in the form of ammonium, followed bynitrate, urea nitrogen and amino acids. This is because NH4-Nassimilation requires less energy than NO3-N, and NO3-N requires lessthan urea nitrogen. Apart from consumption by algae and plant, NH4-N reduction could also be due to nitrification–denitrification causedby bacteria. NH4-N is transformed to NO2-N and then to NO3-N as thefinal form [37]. In this form, nitrogen is most easily taken up by greenplants rooted in the substrate or floating in the water. On the otherhand, E. crassipes and P. stratiotes accumulate detritus and organicmatters that are rapidly mineralized releasing NH4-N which is latertransformed to NO2-N and NO3-N by nitrifying bacteria. As a result,NH4-N reductions in themacrophytes tankswere not as large as in thecontrol tanks [59]. These resultswere similar to the studies by SooknahandWilkie [60] where NH4-N reduction was 99.6% and Jayaweera andKasturiarachchi [61]with 100%removal of total nitrogen. Tripathi andShukla [12] also recorded that E. crassipes showed a remarkable abilityto remove NH4-N. It could be reduced by 74% when the effluent wascultured for 15 days in E. crassipes culture tank followed by five days inthe algal culture. However, the removal rate was far higher comparedto the results from the experiment conducted by Lu et al. [4] where thereductionwas 23.02%usingwastewater treatedby E. crassipesobtainedfrom a constructed wetland. The current study indicates thatP. stratiotes performed slightly better than E. crassipes in reducingammonia-nitrogen from the wastewater.Supporting Information Table S1, (I) NH4-N, shows the summary of

ANOVA results for the reduction of NH4-N in terms of meanconcentrations due to each plant compared to control for eachbatch. From Fig. 5 and Supporting Information Table S1, (I) NH4-N, itcan be summarized that:

� There was significant reduction of NH4-N by E. crassipes,especially in the first two weeks

� There was significant reduction of NH4-N by P. stratiotes� The performance of P. stratiotes was marginally better than the

performance of E. crassipes in reducing NH4-N� Algae reduced NH4-N more than either E. crassipes or P. stratiotes

3.7.2 Nitrate-nitrogen reduction

Figure 6 shows the concentration of NO3-N in sewage over aretention period of four weeks and the overall average for the fivebatches. The initial sewage had an average concentration of0.5mg L� 1 (NO3-N). The differences of NO3-N concentrations before

Figure 5. Concentration of ammonia-nitrogen in sewage over retention offour weeks.



and after the introduction of both plants were highly significant.They show that E. crassipes and P. stratiotes were efficient in strippingNO3-N. The figure demonstrates that E. crassipes generally performedslightly better than P. stratiotes. The concentrations of NO3-N in thecontrol tanks consistently increased over the weeks. It is presumedthat the algae present in the untreated water tanks could notmaintain nor reduce the NO3-N concentration. The concentrationsof NO3-N rose drastically to 3.9mg L� 1 (780%) from the average of0.5mg L� 1 initially. It increased to 19.4mg L� 1 at the end of thefourth week representing a 500% increase compared with the end ofthe first week. On the contrary, NO3-N concentration in sewagetreated with E. crassipes increased to 2.4mg L� 1 (430%) over the firstweek and to 4.2mg L� 1 (175% of first week) by the end of the fourthweek. The corresponding figures for P. stratiotes are 3.1mg L� 1 (620%)and 2.8mg L� 1 (reduction of 10% in the first week). It was noticeablethat the uptakes of NO3-N by both macrophytes were remarkablyhigh compared to the uptakes by algae. This is shown by theconcentration of NO3-N in the untreated sewage that had rapidincrements at the end of each experiment. The uptake by E. crassipeswas significant compared to untreated sewage by 29.6%, whilst NO3-N uptake by P. stratiotes was higher than E. crassipes by 31.1%. Thesame results were also reported by Reddy and DeBusk [2] and Reddyet al. [62] where the reduction was in the range of 78 to 81%. Tripathiand Shukla [12] recorded 61% removal of NO3-N from 1.64 to0.64mg L� 1 in 15 days in E. crassipes culture. In order to lower theNO3-N concentration, they cultured the effluent with algae for fivedays and NO3-N was reduced by 17.6% to 0.35mg L� 1. Meanwhile, inthe current experiment, NO3-N concentrations remained more orless the same indicating that the plants did play a role in preventingit from increasing.The concentration increase of NO3-N in the tanks was 0.6mg/week

for E. crassipes, 3.3mg/week for P. stratiotes and 4.75mg/week for the

control. From the analyses, it is observed that both macrophytes inthe treatment tanks reduced the NO3-N significantly, but the processtook place only after reduction of NH4-N. This study supports thefindings of Aoi and Hayashi [10] where the NH4-N was removed priorto the NO3-N. From the graphs, sewage in the control tank shows adrop in NH4-N but not in the NO3-N concentrations. The samefindings were also observed by Tripathi and Shukla [12], whoattributed it to the possible utilization of NH4-N by algae, leaving theNO2-N and the NO3-N in the sewage.Supporting Information Table S1, (II) NO3-N, shows the summary

of ANOVA results for the reduction of NO3-N in terms of meanconcentrations due to each plant compared to control. From Fig. 6and Supporting Information Table S1, (II) NO3-N, it can besummarized that:

� Compared to the drastic increase of NO3-N in the control tank,E. crassipes slowed down the increase of NO3-N concentration.

� Compared to the drastic increase of NO3-N in the control tank,P. stratiotes slowed down the increase of NO3-N concentration.

� The performance of E. crassipes was significantly better than theperformance of E. crassipes in reducing NO3-N especially duringthe first three weeks.

� Algae did not reduce the concentration of NO3-N in sewage.

3.7.3 Nitrite-nitrogen reduction

Figure 7 shows the concentration of NO2-N in sewage over aretention period of four weeks and the overall average for the fivebatches. It shows the initial average concentration increased from0.0034mgL� 1 to an average of 9.5mg L� 1 for E. crassipes, from0.0034mgL� 1 to an average of 0.0036mg L� 1 for P. stratiotes and from0.1634mgL� 1 to an average of 6.92mg L� 1 for control of NO2-N at theend of the first week.

Figure 6. Concentration of NO3-N in sewage over retention of four weeks.

Figure 7. Concentration of NO2-N in sewage over retention of four weeks.

8 Z. Ismail et al.


Subsequently, based on the end-of-first-week concentrations,there was a decrease of 56% for E. crassipes, an increase of 11% forP. stratiotes and a decrease of 99% for control. NO2-N is unstable.There were no consistent patterns shown in the figure but it can beobserved that the concentration of NO2-N was maintained in thetanks with P. stratiotes while there were small increases with timeindicated in the tank with E. crassipes and the control tank. SinceNO2-N is an intermediate of the oxidation of NH4-N to NO3-N, it wasobserved that the amount of utilized NO2-N was very small. In theenvironment, natural nitrogen cycling process involves bacteria toreduce nitrates or ammonium ions to nitrites. Normally, it does notallow excessive amounts of nitrates or nitrites to accumulate in theenvironment. NO3-N is denitrified by a complex of bacteria to formN2 and a smaller amount of N2Owhich diffuses throughwater to theatmosphere or escapes as bubbles. It may also escape through theaerenchyma of the plant itself. These explain why NO2-Nconcentration is found in small amounts in the environment. Ingeneral, the NO2-N concentration in the control tanks was quitedifferent from those tanks with plants.Although there was no clear pattern of NO2-N uptake, it can be

observed that NO2-N concentrations in sewage treated by P. stratioteswere consistently lower compared to the concentrations in sewagetreatedwith E. crassipes and untreated water. However, there were nosignificant differences in NO2-N reduction between the treatments.The rates of increase of concentration of NO2-N from the initialvalues for the first three weeks were 1.1mg/week for E. crassipes,0.5mg/week for P. stratiotes and 2.27mg/week for the control.Supporting Information Table S1, (III) NO2-N, shows the summary

of variance analyses results for the reduction of NO2-N in terms ofmean concentrations due to each plant compared to control. FromFig. 7 and Supporting Information Table S1, (III) NO2-N, it can besummarized that:

� There was an apparent increase of NO2-N by E. crassipesespecially in the first two weeks

� There was no significant reduction of NO2-N by P. stratiotes� The performance of P. stratioteswas significantly better than the

performance of E. crassipes in reducing NO2-N.� Algae contributed to the reduction of NO2-N in sewage.

3.7.4 ortho-Phosphate reduction

Figure 8 shows the concentration of PO4-P in sewage over a retentionperiod of four weeks and the overall average for the five batches. Thefigure shows that the initial sewage had an average concentration of6.5mg L� 1 PO4-P. The rates of uptake of PO4-P from the initialvalues for the first three weeks were 2.55mg/week for E. crassipes,2.2mg/week for P. stratiotes and 0.3mg/week for the control. Theinfluence of phosphorus (P) on growth and nutrient storage byE. crassipes has been studied previously [2, 63]. Eichhornia crassipescould store P in its tissue and the growth rate is positively related tothe P availability in the water [64]. This is similar to nitrogen storagewhere growth rate increases with increased nitrogen amounts inwater. The PO4-P concentrations were reduced greatly in wastewatertreated with E. crassipes and P. stratiotes. PO4-P concentration in thecontrol tank decreased slightly at the beginning, probably due to theutilization by algae. It is believed that algae in the control tankassimilated PO4-P for their growth and in doing so, decreased theconcentration. However, most of the reductions only took place atthe beginning and later increased gradually. This could be due to the

short-lived nature of the algae. Tucker and DeBusk [65] observed thatP was released slowly from the plants and more rapidly fromepiphytic algae on the plants. When algae die, they decompose andnutrients such as NO3-N and PO4-P are secreted consequently andcause these nutrients to increase in the particular water body.Upward trends of PO4-P concentration level in the untreatedwater

were observed where it rose up to average of 8.3mg L� 1 from anaverage of 6.5mg L� 1. In contrast, E. crassipes and P. stratiotes absorbedPO4-P to an average of 2.6mg L� 1 (60.0% reduction) and 2.1mg L� 1

(68% reduction) at the end of the first week also from the sameaverage initial PO4-P concentration. The concentrations for all casesafter the end of the fourth slightly increased: 11% for E. crassipes, 24%for P. stratiotes and 28% for control compared with the end of the firstweek. The ability of PO4-P absorption by both macrophytes andthe differences between the treatments were highly significant(p< 0.05). Overall, E. crassipes performed slightly better thanP. stratiotes. Reddy and DeBusk [2] and Reddy et al. [42] reportedthat PO4-P removal was 54% in one year of field study and 98.5%reduction have also been observed in dairy manure treated withE. crassipes [35]. Nevertheless, in an experiment of three continuousstages of different sewage treatments conducted by Tripathi andShukla [12], it was shown that sewage treatedwith E. crassipes culturefor 15 days could reduce PO4-P concentration by 56.1%.Supporting Information Table S1, (IV) PO4-P, shows the summary

of variance analyses results for the reduction of PO4-Ps in terms ofmean concentrations due to each plant compared to control. FromFig. 8 and Supporting Information Table S1, (IV) PO4-P, it can besummarized that:

� There was significant reduction of PO4-Ps by E. crassipes,especially in the first two weeks

Figure 8. Concentration of PO4-P in sewage over retention of four weeks.



� There was significant reduction of PO4-Ps by P. stratiotes,especially in the first week.

� Overall, the performance of E. crassipes was slightly better thanthe performance of P. stratiotes in reducing PO4-Ps.

� Algae did not reduce the concentration of PO4-Ps in sewage.

4 Conclusions

Eichhornia crassipes and P. stratiotes are suitable for tertiarywastewater treatment agents as they proved to be efficient inimproving the effluent quality. Eichhornia crassipes performs better inreducing NO3-N and slightly better in reducing PO4-P concentrationsin wastewater compared to P. stratiotes. On the other hand,P. stratiotes performs better in reducing NO3-N and marginallybetter in reducing NH4-N concentrations in wastewater compared toE. crassipes. Algae contribute significantly in reducing nutrientconcentrations, especially NH4-N.Use of macrophytes in wastewater treatment is beneficial as they

can easily be harvested and managed. The application is moresuitable in countries with warmer climate like Malaysia as thesunlight is available throughout the year.It is recommended that due to the significant effect of algae and

bacteria in the up-take of nutrients that their roles be more properlyconsidered for future work. It is further recommended that due tothe synergistic effects of the plants studies on their combinedperformance should be conducted.

Acknowledgements

This research was financially supported by University of MalayaResearch Fund (PPP), Project No: PV057-2011B and research facilitieswere provided by Institute of Biological Sciences, University ofMalaya.

The authors have declared no conflict of interest.

References0[1] J. M. P. Ouattara, L. Coulibaly, S. Tiho, A. Ouattara, G. Goure, Panicum

maximum (Jacq.) Density Effect upon Macrofauna Structure inSediments of Pilot-scale Vertical Flow Constructed WetlandsTreating Domestic Wastewater, Ecol. Eng. 2011, 37 (2), 217–223.

0[2] K. R. Reddy, W. F. DeBusk, Growth Characteristics of AquaticMacrophytes Cultured in Nutrient-enriched Water, I. WaterHyacinth, Water Lettuce, (P. stratiotes) and Pennywort, Econ. Bot.1984, 38 (2), 229–239.

0[3] G. N. H. Rahmani, S. P. K. Sternberg, Bioremoval of Lead fromWaterUsing Lemna minor, Bioresour. Technol. 1999, 70, 225–230.

0[4] J. Lu, Z. Fu, Z. Yin, Performance of Water Hyacinth (Eichhorniacrassipes) System in the Treatment of Wastewater from a Duck Farmand the Effects of Using Water Hyacinth as Duck Feed, J. Environ. Sci.2008, 20, 513–519.

0[5] J. Srivastava, A. Gupta, H. Chandra, Managing Water Quality withAquatic Macrophytes, Rev. Environ. Sci. Biotechnol. 2008, 7 (3), 255–266.

0[6] D. D. Yilmaz, H. Akbulut, Effect of Circulation on WastewaterTreatment by Lemna gibba and Lemna minor, Int. J. Phytorem. 2001, 13(10), 970–984.

0[7] S. Alvarado, M. Guédez, M. P. Lué-Merú, G. Nelson, A. Alvaro, C. J.Arroyo, Z. Gyula, Arsenic Removal from Waters by Bioremediationwith the Aquatic Plants Water Hyacinth (Eichhornia crassipes) andLesser Duckweed (Lemna minor), Bioresour. Technol. 2008, 99 (17), 8436–8440.

0[8] E. Awuah, M. Oppong-Peprah, H. J. Lubberding, H. J. Gijzen,Comparative Performance Studies of Water Lettuce (P. stratiotes),Duckweed, and Algal-based Stabilization Ponds Using Low-strength Sewage, J. Toxicol. Environ. Health, Part A 2004, 67 (20–22),1727–1739.

0[9] D. Koné, C. Seignez, C. Holliger, Natural wastewater treatment bywater lettuce (P. stratiotes) for irrigation water reuse in Burkina Faso,in 5th Int. IWA Specialist Group Conference on Waste Stabilisation Ponds:Pond Technology for the New Millennium, 2–5 April, Auckland, NewZealand 2002.

[10] T. Aoi, T. Hayashi, Nutrient Removal by Water Lettuce (Pistiastratiotes), Water. Sci. Technol. 1996, 34 (7–8), 407–412.

[11] S. M. Shirazi, J. Kuwano, H. Kazama, S. Wiwat, Z. Ismail, Response toSwelling and Permeability of Bentonite Using Saline Solution forNuclear Waste Disposal, Disaster Adv. 2011, 4 (1), 41–47.

[12] B. D. Tripathi, S. C. Shukla, Biological Treatment of Wastewater bySelected Aquatic Plants, Environ. Pollut. 1991, 69, 69–78.

[13] M. F. T. Baharuddin, Z. Ismail, S. Z. Othman, S. Taib, R. Hashim, Use ofTime-lapse Resistivity Tomography to Determine Freshwater LensMorphology, Measurement 2013, 46 (2), 964–975.

[14] S. M. Shirazi, M. A. Islam, Z. Ismail, M. Jameel, U. J. Alengaram, A.Mahrez, Arsenic Contamination of Aquifers: Detailed Investiga-tion on Irrigation and Potability, Sci. Res. Essays 2011, 6 (5), 1089–1100.

[15] Z. Ismail, K. Salim, Determination of Critical Factors in Implement-ing River Clean-up Projects: A Malaysian Case Study, Clean – Soil AirWater 2013, 41 (1), 16–23.

[16] S. M. Shirazi, Z. Ismail, S. Akib, Climatic Parameters and NetIrrigation Requirement of Crops, Int. J. Phys. Sci. 2011, 6 (1), 15–26.

[17] F. O. Agunbiade, B. I. Olu-Owolabi, K. O. Adebowale, Phytoremedia-tion Potential of Eichornia crassipes in Metal-contaminated CoastalWater, Bioresour. Technol. 2009, 100 (19), 4521–4526.

[18] J. Kumar, C. Balomajumder, P. Mondal, Application of Agro-BasedBiomasses for Zinc Removal fromWastewater – a Review, Clean – SoilAir Water 2011, 39 (7), 641–652.

[19] D. Sarkar, S. K. Das, P. Mukherjee, A. Bandyopadhyay, ProposedAdsorption–Diffusion Model for Characterizing Chromium(VI)Removal Using Dried Water Hyacinth Roots, Clean – Soil Air Water2010, 38 (8), 764–770.

[20] A. Valipour, V. K. Raman, P. Motallebi, Application of Shallow PondSystem Using Water Hyacinth for Domestic Wastewater Treatmentin the Presence of High Total Dissolved Solids (TDS) and Heavy MetalSalts, Environ. Eng. Manage. J. 2010, 9 (6), 853–860.

[21] A. S. el-Gendy, Modeling of Heavy Metals Removal from MunicipalLandfill Leachate Using Living Biomass of Water Hyacinth, Int. J.Phytorem. 2008, 10 (1), 14–30.

[22] V. C. Arief, K. Trilestari, J. Sunarso, N. Indraswati, S. Ismadji, RecentProgress on Biosorption of Heavy Metals from Liquids Using LowCost Biosorbents: Characterization, Biosorption Parameters andMechanism Studies, Clean – Soil Air Water 2008, 36 (12), 937–962.

[23] S. Chattopadhyay, R. L. Fimmen, B. J. Yates, V. Lal, P. Randall,Phytoremediation of Mercury- and Methyl Mercury-contaminatedSediments by Water Hyacinth (Eichhornia crassipes), Int. J. Phytorem.2012, 14 (2), 142–161.

[24] S. Govindaswamy, D. A. Schupp, S. A. Rock, Batch and ContinuousRemoval of Arsenic Using Hyacinth Roots, Int. J. Phytorem. 2011, 13 (6),513–527.

[25] H. Xia, X. Ma, Phytoremediation of Ethion by Water Hyacinth(Eichhornia crassipes) fromWater, Bioresour. Technol. 2006, 97 (8), 1050–1054.

[26] P. Prasertsup, N. Ariyakanon, Removal of Chlorpyrifos by WaterLettuce (Pistia stratiotes L.) and Duckweed (Lemna minor L.), Int. J.Phytorem. 2011, 13 (4), 383–395.

[27] N. Nesic, L. Jovanovic, Potential Use of Water Hyacinth (E. crassipes)forWastewater Treatment in Serbia, J. Wastewater Treat. 1996, 13, 1–8.

[28] C. O. Akinbile, M. S. Yusoff, Assessing Water Hyacinth (Eichhorniacrassipes) and Lettuce (Pistia stratiotes) Effectiveness in AquacultureWastewater Treatment, Int. J. Phytorem. 2012, 14 (3), 201–211.

10 Z. Ismail et al.


[29] O. M. Hermosilloa, S. Sarquisa, Design Considerations for WasteWater Treatment with Water Hyacinth E. crassipes, Environ. Technol.1990, 11 (7), 669–674.

[30] L. Wang, H. Gan, F. Wang, X. Sun, Q. Zhu, Characteristic Analysisof Plants for the Removal of Nutrients from a ConstructedWetland Using Reclaimed Water, Clean – Soil Air Water 2010, 38(1), 35–43.

[31] V. Dellarossa, J. Céspedes, C. Zaror, Eichhornia crassipes – BasedTertiary Treatment of Kraft Pulp Mill Effluents in Chilean CentralRegion, Acta Hydrobiol. 2001, 443, 187–191.

[32] R. Dinges, Water Hyacinth Culture for Wastewater Treatment, Report,Texas Department of Health Resources, Austin, TX 1976.

[33] Z. Ismail, A. M. Bedderi, Potential of Water Hyacinth as Heavy MetalRemoval Agent from Refinery Effluents, J. Water Air Soil Pollut. 2009,199, 57–65.

[34] K. K. Moorhead, K. R. Reddy, D. A. Graetz, Water HyacinthProductivity and Detritus Accumulation, Acta Hydrobiol. 1988, 157,179–185.

[35] R. G. Wetzel, Limnology, 2nd Ed., Saunders College, Philadelphia1983, 858pp.

[36] G. Urbanc-Ber�ci�c, A. Gaberš�cik, The Influence of Temperature andLight Intensity on Activity of Water Hyacinth (Eichhornia crassipes(Mart.) Solms.), Aquat. Bot. 1989, 35, 403–408.

[37] R. Van Der Weert, G. E. Kamerling, Evapotranspiration of WaterHyacinth (Eichhornia crassipes), J. Hydrol. 1974, 22, 201–212.

[38] K. R. Reddy, M. Agami, J. C. Tucker, Influence of Nitrogen SupplyRates on Growth and Nutrient Storage byWater Hyacinth (Eichhorniacrassipes) Plants, Aquat. Bot. 1989, 36, 33–43.

[39] K. R. Reddy, M. Agami, J. C. Tucker, Influence of Phosphorus onGrowth and Nutrient Storage by Water Hyacinth (Eichhornia crassipes(Mart.) Solms) Plants, Aquat. Bot. 1990, 37, 355–356.

[40] B. Gopal, Water Hyacinth, Elsevier, Amsterdam 1987, 471 pp.

[41] Government of Malaysia. Environmental Quality Act 1974 (Sewage andIndustrial Effluents Regulations 1978), Department of Environment,Malaysia 1974.

[42] G. K. Reid, R. D. Wood, Ecology of Inland Waters and Estuaries, 2nd Ed.,D. Van Nostrand Company, New York 1976, 485pp.

[43] H. J. Fallowfield, N. J. Cromar, L. M. Evison, Coliform Die-off RateConstants in a High Rate Algal Pond and the Effect of Operationaland Environmental Variables, Water Sci. Technol. 1996, 34 (11), 141–147.

[44] A. Poi de Neiff, J. J. Neiff, O. Orfeo, R. Carignan, QuantitativeImportance of Particulate Matter Retention by the Roots ofEichhornia crassipes in the Paraná Floodplain, Aquat. Bot. 1994, 47,213–223.

[45] K. K. Moorhead, D. A. Graetz, K. R. Reddy, Water Hyacinth Growth inAnaerobic Digester Effluents, Biol. Wastes 1990, 34, 91–99.

[46] R. G.Wetzel, G. E. Likens, Limnological Analyses, 3rd Ed., Springer, NewYork 2000, 429pp.

[47] R. Dinges, Upgrading Stabilization Pond Effluent byWater HyacinthCulture, J. Water Pollut. Control Fed. 1978, 833–845.

[48] S. Nakai, M. Hosomi, M. Okada, A. Murakami, Control of AlgalGrowth by Macrophytes and Macrophyte-extracted Bioactive Com-pounds, Water Sci. Technol. 1996, 34 (7–8), 227–235.

[49] T. Watanuki, T. Kaise, H. Mineo, Inhibition of Anabaena Cylindrical(Cyanophyceae) Growth by Extracts of Water Weeds Using the PaperDisc-agar Method, Jpn. J. Water Treat. Biol. 1990, 26 (1), 1–5.

[50] G. Aliotta, P. Monaco, G. Pinto, A. Pollio, L. Previtera, PotentialAllelochemicals from Pistia stratiotes L., J. Chem. Ecol. 1991, 17 (11),2223–2234.

[51] K. Saito, M. Matsumoto, T. Sekine, I. Murakoshi, InhibitorySubstances from Myriophyllum brasilience on Growth of Blue-greenAlgae, J. Nat. Prod. 1989, 52 (6), 1221–1226.

[52] R. Dinges, Aquatic Vegetation and Water Pollution Control: PublicHealth Implications, Am. J. Public Health 1978, 68 (12), 1202–1205.

[53] S. Sebastian, K. V. K. Nair, Total Removal of Coliforms and E. coli fromDomestic Sewage by High Rate Pond Mass Culture of Scenedesmusobliquus, Environ. Pollut. 1984, 34, 197–206.

[54] D. D. Mara, H. W. Pearson, J. I. Oragui, H. Arridge, S. A. Silva,Development of a new approach to waste stabilization pond design,in Tropical Public Health Engineering (TPHE) Research Monographs No. 5,Civil Engineering Department, University of Leeds, Leeds, UK 2001.

[55] C. R. Picard, L. H. Fraser, D. Steer, The Interacting Effects ofTemperature and Plant Community Type on Nutrient Removal inWetland Microcosms, Bioresour. Technol. 2005, 96 (9), 1039–1047.

[56] T. Suppadit, Nutrient Removal of Effluent from Quail Farm throughCultivation ofWolffia arrhiza, Bioresour. Technol. 2011, 102 (16), 7388–7392.

[57] P. S. Lau, N. Y. F. Tam, Y. S. Wong, Effect of Algal Density on NutrientRemoval from Primary Settled Wastewater, Environ. Pollut. 1995, 89,59–66.

[58] J. J. McCarthy, W. R. Taylor, J. L. Taft, Nitrogenous Nutrition of thePlankton in the Chesapeake Bay, I. Nutrient Availability andPhytoplankton Preferences, Limnol. Oceanogr. 1977, 22 (6), 996–1011.

[59] S. Z. Othman, MSc Thesis, University of Malaya, Kuala Lumpur 2008.

[60] R. D. Sooknah, A. C. Wilkie, Nutrient Removal by Floating AquaticMacrophytes Cultured in Anaerobically Digested Flushed DairyManure Wastewater, Ecol. Eng. 2004, 22, 27–42.

[61] M. W. Jayaweera, J. C. Kasturiarachchi, Removal of Nitrogen andPhosphorus from Industrial Wastewaters by PhytoremediationUsing Water Hyacinth (Eichhornia crassipes (Mart.) Solms), WaterSci. Technol. 2004, 50, 217–225.

[62] K. R. Reddy, K. L. Campbell, D. A. Graetz, K. M. Portier, Use ofBiological Filters for Treating Agricultural Drainage Effluents, J.Environ. Qual. 1982, 11, 591–595.

[63] A. Malik, Environmental Challenge vis à vis Opportunity: The Case ofWater Hyacinth, Environ. Int. 2007, 33, 122–138.

[64] Y. Xie, D. Yu, The Significance of Lateral Roots in Phosphorus (P)Acquisition of Water Hyacinth (Eichhornia crassipes), Aquat. Bot. 2003,75, 311–321.

[65] C. S. Tucker, T. A. DeBusk, Seasonal Variation in the Nitrate Contentof Water Hyacinth (Eichhornia crassipes (Mart) Solms), Aquat. Bot. 1983,15, 419–422.



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