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Phytoremediation of municipal wastewater by using aquatic plants.


More than 70 % of the surface water is polluted by industrial and sewage effluents generated in cities. Aanthropogenic activities releasing untreated sewage water is the major one which contains high molecular weight compounds such as sugars, fats, oils, proteins obtained from domestic and industrial wastes and can causes bad odour, colour, taste and algal growth [11]. Phytoremediation is one of the best solutions for removing pollutants from the sewage and making it suitable for reuse. Macrophytes-based wastewater treatment systems have several potential advantages compared with conventional treatment systems and can act as biofilters in the wastewater treatment technologies [12].

The conventional wastewater treatment process is inconvenient in the form of its operation and also very costly due to its maintenance. Therefore, efforts are made for the use of natural process, which can be used as an eco-friendly and effective source for treatment. Root zone is a bioremediation process that uses various types of plants to remove, transfer, stabilize and destroy contaminants in the wastewater. Plants can extract heavy metals, natural aromatic and hydrocarbon compounds and man-made chemicals such as pesticides, herbicides, fungicides and antibiotics. This approach is a promising clean up technology, which is both low-tech and low cost and reduces remedial cost, restore habitat and clean up contamination [16].

The use of macrophytes such as Pistia and Eichhornia for phytoremediaion of wastewater polluted by organic and inorganic pollutants was investigated by Elumalai et al., [8] and Fonkou et al., [9]. Similarly the capacity of vascular aquatic plants to assimilate nutrients from polluted waters is well recognized viz, duckweed and Azolla offer potential alternatives for treating sewage. The use of Azolla, an aquatic fern with high growth rate and productivity, seems to be very promising to improve treated urban wastewater quality. The biosorption and bioadsorvent of N[O.sub.3.sup.-2], P[O.sub.4.sup.-2] and S[O.sub.4.sup.-2] from sewage water using Azolla is well proven fact [14]. Azolla has been used extensively and effectively for green manure in rice field. Interest in the use of this plant as a biological filter for the renovation of wastewater has increased nowadays [18]. Duckweed (Lemna minor) is a floating aquatic macrophyte, which occur worldwide on the surface of nutrient rich fresh and brackish water. It is used in water quality improvement, to monitor heavy metals, removal of nutrients, soluble salts, organic matter and suspended solids by accumulating these compounds selectively. It has some unique physiological properties (small size, rapid growth between pH 5 and 9 and vegetative propagation), which make it an ideal system for phytoremediation [13]. The aquatic macrophytes work most efficiently when wastewater is diluted in different ratios because the pollutants are also diluted, which become suitable for growth and survival of these plants. The diluted wastewater is making favourable conditions for phytoremediation.

Several researchers have worked on phytoremediation of municipal wastewater using various aquatic plants. However the success of implementing this technology is depending on selection of appropriate and most efficient plant species. The functioning of selected plant system depends on type of contaminants in the wastewater and growth of the plants used. Present study was focused to find out efficient and better functioning plant species for phytoremediation of sewage water at different levels of dilution and the testing was done to know the highly suitable plant species for wastewater treatment.


Wastewater sample (about 120 litters) was collected from sewage treatment plants of Pune Municipal Corporation located at Bopodi during the year 2012-13 and brought to the laboratory in plastic containers for conducting the experiment. The aquatic plants selected for phytoremediation viz Azolla pinnata and Lemna minor were collected freshly from natural pond at Horticulture Research Station Ganesh Khind, Pune, and brought to the laboratory in plastic bags along with water. These plants were cleaned properly to remove dirt and dust under tap water and stabilized in laboratory conditions for 2-3 days to normalise their growth.

Factorial arrangement with randomized complete block design with three replications was used to conduct the experiment at Department of Environmental Science, University of Pune, India. Treatments included P0: no plant, P1: Azolla pinnata and P2: Lemna minor and ratios of wastewater: distilled water were R0: 100 % wastewater, R1:75 % wastewater + 25 % distilled water, R2: 50 % wastewater + 50 % distilled water and R3: 25 % wastewater + 75 % distilled water. The wastewater after dilution with distilled water in the proportion as mentioned above was poured into rounded, transparent plastic trough (18x20x20cm) having surface area 254 [cm.sup.2]. The capacity of each plastic trough was about 5 litters. Selected plants, 5 g each of Azolla pinnata and Lemna minor were inoculated separately in above containers as per the experimental design. The laboratory conditions were maintained uniform throughout the experimental period (30 days).

All the physicochemical characteristics of wastewater samples (pre and post treatments) such as pH, EC, TDS, N[O.sub.3.sup.-2], P[O.sub.4.sup.-2] and S[O.sub.4.sup.-2] were determined by using standard methods (APHA, AWWA, WEF, 2005). The results were analyzed statistically by using MSTATC computer software and a comparison of recorded data was done on the basis of Duncan's multiple range tests at Alfa level 5%.



The pH range during phytoremediation plays a key role and favourable pH for the growth of plants varied according to species used for purification and dilution ratios. The results of present investigation indicated that aquatic plants, dilution of wastewater and combination of both (aquatic plants and diluted wastewater, 1:3) have caused significant reduction in pH value as compare to initial stage (Fig. 1 and Table 1). Slightly alkaline pH was reported by Elumalai et al., [8]. The results of present study are in agreement with above work. According to Azeez and Sabbar, [2] and Sengar et al., [15] release of CO2 during phytoremediation is positively correlated with change in pH.


The electrical conductivity at final stage was reduced when compared to initial stage in all treatments. Highest EC was recorded in absence of aquatic plants as compare to the presence of Azolla and Lemna (Fig. 2 A). The EC was higher in municipal wastewater without dilution with DW, while the lowest EC was observed with highest dilution ratio (1:3) (Fig. 2 B). In combination treatment of dilution with DW and aquatic plants EC value was reduced as compare to no dilution and no plants. The EC value goes on decreasing along with increasing dilution and use of plants. The lowest EC was in treatment (1:3) dilution with Lemna (32 [micro]mohs/cm) followed by Azolla (41 [micro]mohs/cm) (Table 1). The results clearly revealed reduction in EC in presence of plants as well as with dilution of sewage wastewater. The results of present investigation are inconformity with Chavan and Dhulap, [4]. They noted the reduction in EC by 32 to 80 % during sewage treatment using Cana indica, which is promising emergent macrophytes for sustainable used in wastewater treatment. The range of EC mostly depends on the concentration of various types of soluble salts in wastewater. The decrease in EC during phytoremediation indicated the heavy uptake of salts by both the plants used. Dipu et al., [6] and Dar et al., [5] recorded reduction in EC with dilution and in presence of Pistia and Eichhornia species respectively.


The total dissolved solids at final stage were decreased significantly in presence of Azolla and Lemna as compare to their initial stage (Fig. 3 A). The TDS was decreased by increasing dilution and the minimum value was in dilution treatment 1:3 (Fig. 3 B). The TDS value of municipal wastewater varied with interaction between plant species and dilution ratios. The lowest value (21.3 mg/[l.sup.-]) (1: 3) was observed in presence of Lemna and highest dilution it was followed by Azolla (26.7 mg/[l.sup.-]) (Table 1). Azeez and Sabbar, [2] reported very high reduction in TDS (48.9 %) in phytotreatment of wastewater with duckweed. They attributed the decrease in TDS to the capacity of plants to take some organic and inorganic ions. Results of present study corroborates with above findings. Dipu et al., [6] observed very high reduction in TDS for dairy effluents using some aquatic macrophytes. Chavan and Dhulap, [4] also reported 25 to 50 % reduction in TDS by using Cana indica. El-Kheir et al, [7] observed significant reduction in TDS, improving the quality of domestic wastewater by using Lemna. Decrease in TDS reflects improvement in quality of wastewater due to phytoremediation.





Nitrates are commonly present in various forms in the wastewater and are important for plant growth. The nitrate content in presence of Azolla and Lemna was reduced by 66.3 and 73.5 % as compare control respectively (Fig. 4 A). The mean comparison of dilution effect showed lowest N[O.sub.3.sup.-2] (15.11 mg/[l.sup.-]) in 1:3 dilution of wastewater as compare to no dilution (98.44 mg/[l.sup.-]) (Fig. 4 B). The impact of dilution and plant species clearly indicated that N[O.sub.3.sup.-2] content was significantly lowered in presence of Azolla (3 mg/[l.sup.- ]) followed by Lemna (4 mg/[l.sup.-]) in (1: 3) ratio (Table 2). Azeez and Sabbar, [2] and El-Kheir et al., [7] reported the reduction of N[O.sub.3.sup.-2] in phytoremediation process by using Lemna. According to Chavan and Dhulap, [3] the range of reduction in nitrates varied with type of plant species used and they reported 42 to 70 % reduction in nitrate. The significant fall in nitrate was attributed to its uptake for growth and metabolisms of the plant system used. Vipat et al, [17] also reported the decreasing in N[O.sub.3.sup.-2] due to plant uptake and ions exchange.


Phosphate is a major pollutant in wastewater and responsible for eutrophication. High concentration of phosphate has negative effects on the structure of aquatic ecosystems [10]. Therefore it must be removed from wastewater during phytoremediation system before discharge into environment. The results of present investigation showed that phosphate content was decreased at final stage when compared with initial stage. The decreased was by 74 and 83 % with Azolla and Lemna as compare to control respectively (Fig. 5 A). The influence of dilution of municipal wastewater in different proportions indicated minimum phosphate content in the treatment 1:3 dilution (2 mg/[l.sup.-]) as compare to the treatment no dilution (9 mg/[l.sup.-]) (Fig. 5 B). The impact of combination treatment (dilution of wastewater along with Azolla/Lemna) showed that the minimum value was observed in the treatment 1:3 dilution and Lemna (0.3 mg/[l.sup.-]) followed by Azolla (0.7 mg/l) (Table 2). Many researchers such as Chavan and Dhulap, [3], Sengar et al., [15] and Tripathi and Upadhyay, [16] recorded very high reduction in P[O.sub.4.sup.-2] content in sewage water, dairy effluent and wastewater using different aquatic plants such as Panicum, Algal species and Lemna respectively.


Sulphate in very high concentration becomes the limiting factor for growth of plants and hence its removal is essential during phytoremediation so that the treated wastewater can be reused for agriculture purpose. The results of present study showed that S[O.sub.4.sup.-2] content was decreased at final stage as compare to initial stage. Sulphate content at final stage was maximum (37 mg/[l.sup.-]) in absence of plant species but it was highly reduced to minimum level (11 mg/[l.sup.-]) in presence of Lemna (Fig. 6 A). The mean comparison of ratios at final stage indicated decrease in S[O.sub.4.sup.-2] with increasing dilution of sewage wastewater with DW and the lowest S[O.sub.4.sup.-2] content was noted in 1:3 dilution ratios (Fig. 6 B). The interaction between plant species used and the dilution ratios (1:3) revealed that minimum SO4-2 content (1.3 mg/[l.sup.-]) was in presence of Lemna followed by Azolla (1.5 mg/[l.sup.-]) (Table 2). Chavan and Dhulap, [3] observed more than 50 % reduction in the level of S[O.sub.4.sup.-2] using the aquatic plant species Panicum. They noted that phytoremediation is most effective in highest dilution and the treated water may be used for agriculture. They further stated that locally adapted aquatic plants are more effective. Priya et al., [12] stated that wastewater treatment system using aquatic macrophytes like Lemna, Azolla, Pistia etc has proved to be an efficient mechanism for treating domestic as well as industrial wastewater.




Summary and conclusion:

Phytoremediation of municipal wastewater using aquatic macrophytes such as Azolla and Lemna has proved to be a very convenient, highly effective and mostly nature friendly technology. It is low cost and sustainable, protecting the environment from water pollution, which is very threatening to the survival of human beings. From the results of present investigation it can be concluded that Azolla and Lemna will serve the purpose of wastewater treatment in municipal areas which are easily manageable. Amongst both them Lemna was more efficient for reducing almost all the parameters studied in the state of dilution of wastewater (1: 3) as it is highly convenient for active growth of these plants, which enable them to function at optimum level for improving the quality of wastewater.


Article history:

Received 15 November 2013

Received in revised form 14

January 2014

Accepted 20 January 2014

Available online 25 February 2014


The authors express their sincere thanks to Head of Environmental Science Department, University of Pune, Pune-7 for providing the research facility to conduct this experiment and for giving inspiration, guidance as well as technical support.


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[2] Azeez, N., M. and A.A. Sabbar., 2012. Efficiency of duckweed (Lemna minor L.) in phytotreatment of wastewater pollutions from basrah oil refinery. Journal of Applied Phtotechnology in Environmental Sanitation., 1(4): 163-172.

[3] Chavan, B., L. and V.P. Dhulap, 2012a. Sewage treatment with constructed wetland using Panicum maximum forage grass. Journal of Environ Sci and water Resources., 1(9): 223-230.

[4] Chavan, B.L. and V.P. Dhulap, 2012 b. Optimization of polluted concentration in sewage treatment using constructed wetland through pytoremediation. International Journal of Advanced Research in Engineering and Applied Science, 1(6).

[5] Dar, S.H.D., M. Kumawat, N. Singh and K.A. Wani, 2011. Sewage treatment potential of water hyacinth (Eichhornia crassipes). Research Journal of Environmental Science, 5(4): 377-385.

[6] Dipu, S., A. Anju, V. Kumar and S.G. Thanga, 2010. Pytoremediation of dairy effluent by constructed wetland technology using wetland macrophytes. Global Journal of Environmental Research, 4(2): 90-100.

[7] El-Kheir, W., A.G. Smail, F.A. El-Nour, T. Tawfik and D. Hammad, 2007. Assessment of the efficiency of duckweed (Lemna gibba) wastewater treatment. International Journal of Agric and Biology, 9(5): 681-687.

[8] Elumalai, S.K., R. Somasundaram, S. Sakthivel, V. Ramganesh Prakasam, 2013. Phytoremediation of metals by aquatic plants at natural wetlands in major lakes (Industrial city) hosur, krishnagiri district, India. International Journal of Science Innovations and Discoveries, 3(1): 135-145.

[9] Fonkou, T., P. Agendia, I. Kengne, A. Akoa and J. Nya, 2002. Potential of water lettuce (Pistia stratiotes) in domestic sewage treatment with macrophytic lagoon system in Cameroon. Proceedings of International Symposium on Environmental Pollution Control and Waste Management, pp: 709-714.

[10] Kadlec, R.H and S.D. Wallace, 2008. Treatment wetland, 2nd. CRC Press, Boca Raton, F.L.

[11] Metcalf, Eddy, 1991. Wastewater engineering. Treatment, disposal, reuse 3rd ed. McGraw-Hill Int. Ed. Singapore.

[12] Priya, A.K., Avishek, G. Pathak, 2012. Assessing the potentials of Lemna minor in the treatment of domestic wastewater at pilot scale. Environ Monit Assess, 184: 4301-4307.

[13] Radic, S.D., P. Stipanticev, I. Cvjrtko, L. Mikelic, M.M. Rajcic, S. Sirac, B.P. Kozlina, M. Pavlica, 2009. Ecotoxicological assessment of industrial effluent using ducweed (Lemna minor L.) as a test organism.

[14] Rakhshaee, R.M., M. Khosravi, T. Ganji, 2006. Kinetic modelling and thermodynamic study to remove Pb (II), Cd (II) and Zn (II). From aqueous solution using dead and living Azolla filiculoides. Journal of Hazardous Materials, B1 34: 120-129.

[15] Sengar, R.M., S.K. Singh and S. Singh, 2011. Application of phycoremediation technology in the treatment of sewage water to reduce pollution load. Indian. J.Sci. Res., 2(4): 33-39.

[16] Tripathi, B., D. and Alka, R. Upadhyay, 2003. Dairy effluent polishing by aquatic macrophytes. Water, Air, and Soil Pollution, 143: 377-385.

[17] Vipat, V., UR. Singh S.K. Billore, 2008. Efficiency of root zone technology for treatment of domestic wastewater: field scale study of a pilot project in Bhopal. (MP), India. Proc. Of Taal. The 12th World Lake Conf, 995-1003.

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(1) Hossein Azarpira, (2) Pejman Behdarvand & (1) Kondiram Dhumal, (1) Gorakh Pondhe

(1) Department of Environmental Sciences, University of Pune, Pune-07-India.

(2) Department of Agricultural and Natural Resources, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran.

Corresponding Author: Hossein Azarpira, Department of Environmental Sciences, University of Pune, Pune-07-India

Table 1: Interaction effect of plant species and ratios on
pH, EC and TDS of wastewater during phytoremediation

Treatment   pH                EC ([micro]mohs/cm)
            Initial   Final   Initial    Final

P0R0        7.4 a     7.3 a   3555.0 a   3549.0 a
P0R1        7.5 a     7.4 a   2682.0 b   2632.0 b
P0R2        7.4 a     7.2 a   1793.0 c   1768.0 cd
P0R3        7.3 a     7.2 a   881.3 d    866.7 e
P1R0        7.5 a     7.1 a   2355.0 a   1938.0 c
P1R1        7.5 a     7.0 a   2682.0 b   537.7 f
P1R2        7.4 a     7.0 a   1793.0 c   176.0 g
P1R3        7.2 a     7.1 a   881.3 d    41.0 g
P2R0        7.3 a     7.2 a   3555.0 a   1592.0 d
P2R1        7.4 a     7.3 a   2682.0 b   472.0 f
P2R2        7.4 a     7.2 a   1793.0 c   121.3 g
P2R3        7.3 a     7.2 a   881.3 d    32.0 g

Treatment   TDS (mg/[l.sup.-])
            Initial    Final

P0R0        2355.0 a   2325.0 a
P0R1        1805.0 b   1789.0 b
P0R2        1153.0 c   1135.0 d
P0R3         592.0 d    569.0 e
P1R0        2355.0 a   1317.0 c
P1R1        1805.0 b    358.3 f
P1R2        1153.0 c    113.0 g
P1R3         592.0 d     27.0 h
P2R0        2355.0 a   1109.0 d
P2R1        1805.0 b    325.0 f
P2R2        1153.0 c     85.3 g
P2R3         592.0 d     21.3 h

Means with different letters are significantly
different at P = 0.05, using Duncan's
Multiple Range Test.

Table 2: Interaction effect of plant species and ratios on
N[O.sub.3.sup.-2], P[O.sub.4.sup.-2] and S[O.sub.4.sup.-2]
content of wastewater during phytoremediation

Treatment   N[O.sub.3.sup.-2] content (mg/[l.sup.-])
            Initial    Final

P0R0        153.3 a   143.3 a
P0R1        118.0 b   116.3 b
P0R2         76.0 c   70.7 d
P0R3         43.0 d   38.3 e
P1R0        153.3 a   80.0 c
P1R1        118.0 b   35.0 e
P1R2         76.0 c    6.7 g
P1R3         43.0 d    3.0 g
P2R0        153.3 a   71.0 d
P2R1        118.0 b   19.0 f
P2R2         76.0 c    4.0 g
P2R3         43.0 d    4.0 g

Treatment   P[O.sub.4.sup.-2] content (mg/[l.sup.-])
            Initial    Final

P0R0        16.0 a    14.7 a
P0R1        11.3 b    10.3 b
P0R2        10.0 b     9.0 c
P0R3         7.0 c     5.0 e
P1R0        16.0 a     7.3 d
P1R1        11.3 b     2.7 f
P1R2        10.0 b     1.0 gh
P1R3         7.0 c     0.7 hi
P2R0        16.0 a     5.0 e
P2R1        11.3 b     1.3 g
P2R2        10.0 b     1.0 gh
P2R3         7.0 c     0.3 i

Treatment   S[O.sub.4.sup.-2] content (mg/[l.sup.-])
            Initial   Final

P0R0        64.7 a    59.7 a
P0R1        44.3 b    42.0 b
P0R2        36.7 b    32.7 c
P0R3        17.7 d    13.0 f
P1R0        65.3 a    29.7 d
P1R1        44.3 b    15.0 e
P1R2        36.7 c     3.7 h
P1R3        17.7 d     1.5 i
P2R0        64.7 a    29.3 d
P2R1        44.3 b     9.3 g
P2R2        36.7 c     3.0 h
P2R3        17.7 d     1.3 i

Means with different letters are significantly
different at P = 0.05, using Duncan's
Multiple Range Test.
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Article Details
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Author:Azarpira, Hossein; Behdarvand, Pejman; Dhumal, Kondiram; Pondhe, Gorakh
Publication:Advances in Environmental Biology
Article Type:Report
Geographic Code:7IRAN
Date:Dec 1, 2013
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