International Research Journal of Environment Sciences________________________________ ISSN 2319–1414Vol. 2(2), 6-14, February (2013) Int. Res. J. Environment Sci. International Science Congress Association 6 Developing a Pilot Scale Angular Horizontal Subsurface Flow Constructed Wetland for Treatment of Sewage through Phytoremediation with Colocasia esculenta Chavan B.L. and Dhulap V.P. Department of Environmental Science, School of Earth Sciences, Solapur University, Solapur, Maharashtra, INDIA Available online at: www.isca.in Received 30th December 2012, revised 13th January 2013, accepted 30th January 2013 AbstractPhytoremediation is the technique based on the use of plants to remediate sites contaminated with organic and inorganic pollutants. This technology is rapidly growing as is helpful to growing industries. Colocasia esculenta is a tropical plant grown primarily for its edible corm and the root vegetables. It has many names like Taro and Eddoe. It is a wide spread emergent aquatic plant, generally grows near bogs, streams, river pools and many shallow aquatic bodies. This plant is useful for wastewater treatment by its plant-root–rhizome system. In the present study, Colocasia esculenta is used for the treatment of sewage to test its pollutant absorption capacity. The studies aim at developing and assessing sewage treatment efficiency through a Angular Horizontal Subsurface Flow Constructed wetland pilot scale plant for treatment of sewage for sewage treatment process of Solapur city to recycle and reuse. The treated and untreated samples of sewage with different dilutions viz. 10%, 20%, 30%, 40%, 50%, 60%,70%, 80%, 90% and 100% were tested and compared with a blank (without Colocasia esculenta) as a control. The results reveal that the average reduction in EC was by 23.68%, TSS by 46.15%, TDS by 50.08%, TS by 49.34%, BOD by 54.30%, COD by 58.69%, NO by 59.48%, PO by 46.99% and SO by 39.32% against treatment of sewage in the control bed in which EC was reduced by 11.62%, TSS by 27.90%, TDS by 32.66%, TS by 29.94%, BOD by 31.26%, COD by 39.81%, NO by 23.93, PO by 20.89 and SO by 16.48% respectively. The soil samples were analyzed at before use and after use in the constructed wetland as bedding media. Considerable reduction in pollutants using Colocasia esculenta plant bed was noticed against the bed treatment without Colocasia esculenta plant. It is concluded that Colocasia esculenta is capable for the treatment of sewage. Keywords: Phytoremediation, Angular Horizontal Subsurface Flow, constructed wetlands, sewage treatment, Horizontal Subsurface flow, Colocasia esculent. Introduction Today, water availability is a problem all over the world in terms of both quantity and quality. This problem is getting worsened as the world population and industrialization is increasing and climate change is affecting water resources, mainly in water stressed developing countries. Wastewater discharges are causing eutrophication and water borne diseases. The situation is getting worse with rapid urbanization where adequate sanitation and wastewater treatment facilities are lacking. The treatment of wastewater using Constructed Wetland (CW) is one of the suitable treatment systems, used in many parts of the world. This system seems to have the potential to be one of the sustainable solutions in treating and then discharging the huge quantity of wastewater and getting access to safer drinking water. Constructed wetlands (CWs) are treatment systems have been designed to accomplish natural processes with wetland substrates, vegetation and the associated microbial assemblages to help in treating wastewaters and take advantage of the processes that occur in natural wetlands within the more controlled environment1, 2. The Constructed Wetlands (CWs) are designed to mimic natural wetlands with much high degree of treatment for pollution control. Despite recognizing CW as an alternative for conventional wastewater treatment, little has been done in developing countries. Conventional (e.g. biological) and advanced wastewater treatment technologies like activated sludge followed by membrane filtration or chemical treatment are used in many countries for wastewater treatment. However, considering their costs, contaminant removal efficiencies and operational skills required for advanced wastewater treatments, natural treatment systems might be more sustainable and appropriate for developing countries. These natural wastewater treatment systems are used to improve treatment efficiencies by using natural processes. These natural processes of treatment include physical, chemical and biological mechanisms and require less energy, reduce the use of chemicals and have a small carbon footprint in comparison with conventional systems. In terms of contaminant removal efficiency, cost reduction and simplicity, CWs are more suitable. Among the different types of CWs, Horizontal Sub-surface Flow Constructed Wetlands (HSSFCWs) are most widely used and became International Research Journal of Environment Vol. 2(2), 6-14, February (2013) International Science Congress Association low- impact alternatives to more conventional wastewater treatment processes. In a typical HSSFCW, wast ewater is maintained at a constant depth and flows horizontally below the surface of the bed has been proven to be efficient in removing pollutants, organic matter6,7,8 and pathogens . In HSSFCWs, organic matter is decomposed by both aerobic and anaer obic processes, but an insufficient supply of oxygen in this system greatly reduces the performance of aerobic biological oxidation nitrification is the main limiting factor for N removal due to low oxygen availability11,12. Artificial aer ation would favor aerobic organic matter oxidation and nitrification in HSSFCW main operational problem in CW is progressive clogging of the porous support and growth media, which diminishes the hydraulic performance, and consequently affects the pol removal efficiency and life span of the system The growth of biofilm and microbial activity may depend on oxygen availability in the CW and thus may affect the solid removal efficiency and clogging. The exact mechanisms of granular medium clogging are still unclear. It is believed that accumulation of organic and inorganic solids, growth of biofilm, chemical precipitation and deposition, plant debris and swelling of soil colloids are the main causes of clogging collection of micro- organisms surrounded by slime they secrete. Biofilms are mainly comprised of b acteria, fungi, algae and micro- invertebrates. In subsurface flow constructed wetlands (SSFCWs), biofilm (growth of micro- organisms) in substratum pores is regarded as an important factor of causing clogging Study area map shows Research work carried Environment Sciences_______________ _________________________ International Science Congress Association impact alternatives to more conventional wastewater ewater is maintained at a constant depth and flows horizontally below the surface of the bed . It has been proven to be efficient in removing pollutants, organic . In HSSFCWs, organic matter is obic processes, but an insufficient supply of oxygen in this system greatly reduces the performance of aerobic biological oxidation 5,8,10. Moreover, nitrification is the main limiting factor for N removal due to low ation would favor aerobic organic matter oxidation and nitrification in HSSFCW . The main operational problem in CW is progressive clogging of the porous support and growth media, which diminishes the hydraulic performance, and consequently affects the pol lutant removal efficiency and life span of the system 8,10,12,14,15. and microbial activity may depend on oxygen availability in the CW and thus may affect the solid removal efficiency and clogging. The exact mechanisms of granular medium clogging are still unclear. It is believed that solids, growth of biofilm, chemical precipitation and deposition, plant debris and swelling of soil colloids are the main causes of clogging 16. Biofilm is a organisms surrounded by slime they secrete. acteria, fungi, algae and invertebrates. In subsurface flow constructed wetlands organisms) in substratum pores is regarded as an important factor of causing clogging 17. Phytoremediation is the use of plants to reme contamination by the uptake of contaminated water by plants. The phytoremediation technology is uses certain aquatic plants to clean up the water contaminated with metals and organic contaminants. Plants are used to remove or degrade contaminants wit h an old process that occurs naturally in ecosystems as both inorganic and organic constituent’s cycle through these plants. It is an aesthetically pleasing mechanism that can reduce remedial costs, restore habitat and cleanup contamination rather than ent ombing it or transporting the problem to another site10,13,14,18,19. Several techniques can be applied to mitigate clogging, such as pre- treatment, wash back, partial or complete replacement of filter medium and using oxidizing agent like hydrogen peroxid 20,21,22,23 . Bioremediation processes can also be applied to reverse clogging when it is detected. This process includes the indigenous microbial activity to degrade these accumulated organic solids. It is considered to be one of the major factors of sub strate clogging. Among the micro protozoa and micro flagellates are the most important micro fauna groups in CW fed with effluent from wastewater treatment24 . The grazing protozoa may indirectly stimulate the rate of in situ bioreme diation by controlling bacterial clogging therefore improving permeability 25 development of pilot scale Angular Horizontal Subsurface Flow Constructed Wetland for Phytoremediation of Sewage using Colocasia esculenta with the same treatment mechanism. Figure-1 Study area map shows Research work carried _________________________ ______ ISSN 2319–1414 Int. Res. J. Environment Sci. 7 Phytoremediation is the use of plants to reme diate contamination by the uptake of contaminated water by plants. The phytoremediation technology is uses certain aquatic plants to clean up the water contaminated with metals and organic contaminants. Plants are used to remove or degrade h an old process that occurs naturally in ecosystems as both inorganic and organic constituent’s cycle through these plants. It is an aesthetically pleasing mechanism costs, restore habitat and cleanup ombing it or transporting the Several techniques can be applied to mitigate clogging, such as treatment, wash back, partial or complete replacement of filter medium and using oxidizing agent like hydrogen peroxid e . Bioremediation processes can also be applied to reverse clogging when it is detected. This process includes the indigenous microbial activity to degrade these accumulated organic solids. It is considered to be one of the major factors of strate clogging. Among the micro -invertebrates, ciliated protozoa and micro flagellates are the most important micro fauna groups in CW fed with effluent from wastewater . The grazing protozoa may indirectly stimulate the diation by controlling bacterial clogging 25 . This study is focused on development of pilot scale Angular Horizontal Subsurface Flow Constructed Wetland for Phytoremediation of Sewage using treatment mechanism. International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(2), 6-14, February (2013) Int. Res. J. Environment Sci. International Science Congress Association 8 Material and Methods Experimental site: Purification trials were tested and conducted at the field station of Environmental Science laboratory, located in the Solapur University, Solapur (MS) India (figure 1). Solapur city is the head quarter of Solapur district. It is situated on the south-east fringe of Maharashtra state and lies between 17o 10’ and 18 32’ north-latitude and 7442’ and 76 o 15’ east longitude. Solapur normally has a rain-fall of about 30 inches. However, in certain places, the rain-fall exceeds this figure. There are about 42 rainy days in a year. Even this scanty rain-fall is most unevenly distributed and uncertain leading to famine conditions now and then.Sample collection: For the treatment of sewage, the grab samples were collected from Shelgi nala (Pune naka) located near national highway no. 9 in Solapur city (figure-2 and 3). These samples were treated studies using Colocasia esculenta by phytoremediation (root zone) technique after their pre-treatment characterization. Figure-2 Shelgi Nala sewage disposal site Figure-3 Sewage sampling on site Treatment plant details: Colocasia esculenta is a tropical plant, whose many names such as Taro and Eddoe (figure- 4).Taro is closely related to Xanthosoma and Caladium, plants commonly grown as ornamentals, and like them it is sometimes loosely called elephant ear. Taro was probably first native to the lowland wetlands of Malaysia (taloes). Estimates are that taro was in cultivation in wet tropical India before 5000 BC, presumably coming from Malaysia, and from India further transported westward to ancient Egypt, where it was described by Greek and Roman historians as an important crop. In India, it is known as "arbi" or "arvi". The selected plant Colocasia esculenta belongs to Kingdom–plantae, Order–Alismatales, Family- Araceae, Subfamily- Aroideae, Tribe- Colocasiodeae, Genus– Colocasia and species- C. esculenta as per (L) Schott. This plant is locally known as, ‘Alu’ in the state of Maharashtra. Rhizomes are of plant having different sizes and shapes. Leaves grows up to 40×24.8 cm, sprouts from rhizome, dark green above and light green beneath, triangular-ovate, sub-rounded and mucronate at apex, tip of the basal lobes rounded or sub-rounded. Petiole is of 0.8 -1.2 m in hight. Spathe is up to 25 cm long. Spadix is about 3/5 as long as the spathe, flowering parts up to 8 mm in diameter. Female portion at the fertile ovaries intermixed with sterile white ones26. Figure-4 Plant of Colocasia esculentaFigure-5 Experimental design of AHSSF-CW International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(2), 6-14, February (2013) Int. Res. J. Environment Sci. International Science Congress Association 9 Experimental Design and Methodological approach: Experimental procedures followed in present investigation were similar to those described elsewhere7,8, 10, 12. Colocasia esculenta is one of the prominent adaptive marshy plants in the Solapur region which was used for treatment of wastewater. It was transplanted in the designed wetland system in the Angular Horizontal Subsurface Flow process of constructed wetland (figure-5). Three sets of buckets with different sizes and dimensions were used in each experimental set up. The vertical buckets as holding tank (Inlet) were used to hold the wastewater. The water storing capacity of tank was 30 liters each. The rectangular tub with test plant bed was used as experimental test setup in each set for preparing root zone bed of size 62 cm length and height 35 cm having suitable outlet. The vertical pipe was placed above the tub in an inverted ‘T’ shape for equal distribution of wastewater which was connected with the rubber pipe to the inlet of holding tank in each set. The length of plastic pipe was 40 cm and the holes were provided at the interval of 5 cm and equal flow was adjusted manually through them. Plastic cans were used for the collection of treated water after flowing out from the root zone bed through the outlets. Inlet, Root zone tub and outlet were connected to each other with taps by tubes and plastic water pipes. Treated water samples were collected and analyzed in laboratory. The Angular Horizontal Subsurface Flow constructed wetland or root zone bed for each set was prepared as follows: Three layers were prepared with Pebbles, Sand and Garden soil. The big size pebbles accounting to 20 kg weight making bottom layer of 10 cm height followed by sharp and medium sized 15 kg sand were added to form a middle layer of 10 cm height and 6 kg small size and sieved soil forming upper layer of 10 cm height were used for construction of bed. The pebbles and sand materials were neatly washed with tap water and then arranged in different layers. Selective healthy, small, young, locally available grass saplings of Colocasia esculenta were transplanted which were arranged in rows & columns and covered by layer of small pebbles, sand and soil. The rectangular tub with plant bed was provided with 10slope with slight elevation at the bottom of backside of tub and kept in the slanting position. Inlet and outlet flow rates were adjusted by using bucket and timer. Inlet flow and outlet flow of wastewater were adjusted to maintain Hydraulic Retention Time (HRT) of 4 days (96 hrs). Initially, plants in bed were acclimatized for two weeks with suitable dilutions each time. As the time passed, the concentrations were increased such as 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100% of sewage through plant treatment. These samples were treated using Colocasia esculenta by Phytoremediation technique and other set as control (without plant) also analyzed after their pre-treatment characterization (figure-6). (A)(B)Figure-6 Treatment of sewage through plant set of (A) Colocasia esculenta and (B) set of Control in AHSSF-CWTest samples before and after treatment were analyzed in both sets (Plant bed and control bed) for selective parameters like pH, EC, TSS, TDS, TS, COD, BOD, NO, PO4 and SO using standard method27, 28. Soils used in before and after treatment in both beds of CWs were analyzed. Finally, pollution reduction efficiency and treatment efficiency of the test plant were calculated. Results and Discussion The treatment efficiency of the Angular Horizontal Subsurface Constructed Wetland unit was examined by wastewater quality parameters such as pH, EC,TSS,TDS,TS,BOD,COD, Nitrate, Phosphate and Sulphate respectively, in the inlet and outlet of wastewater at HRT of 4 (96 hrs) days. The treated and untreated samples of sewage with different dilutions viz. 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100% were tested and International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(2), 6-14, February (2013) Int. Res. J. Environment Sci. International Science Congress Association 10 compared with a reference set as control (without Colocasia esculenta). The results in the set of Colocasia esculenta reveal that the maximum pollution reduction efficiency was observed in 70% sewage concentration. The characteristics of the wastewater collected from inflow and outflow of both sets of CWs are presented in the table 1 and table 3. The pollution reduction efficiencies of both CW are shown in the table 2, 4 and figure-7 and figure-8. The soil used as bed media was collected from nursery and its characteristics are studied before use as media for treatment and after treatment. The bed media is for supporting in plant Colocasia esculenta in bed CW and of in Control bed (table 5). Table-1 Sewage treatment performance (Before and after treatment) in the Angular Horizontal Subsurface Flow Constructed Wetland using Colocasia esculenta after 4 days (96 hrs) HRTs. ‘B’ means Before Treatment and ‘A’ means After Treatment. Table-2 Percentage reduction in various parameters using Colocasia esculenta after the sewage treatment Sewage Concentrations (%) E.C. in % TSS in % TDS in % TS in % BOD in % COD in % NO3 in % PO4 in % SO4 in % 10 7.84 9.73 22.38 20.39 21.30 24.86 24.07 19.44 17.85 20 9.25 9.86 29.24 25.61 24.48 29.25 28.33 22.26 20.51 30 12.93 10.82 33.50 29.66 27.57 33.88 35.78 27.02 26.41 40 15.44 21.55 37.15 34.58 30.70 37.33 39.14 32.86 30.30 50 17.82 29.65 41.05 39.30 34.36 41.31 45.30 36.34 34.61 60 20.30 37.28 44.88 43.43 40.52 47.22 54.64 39.56 36.90 70 23.68 46.15 50.08 49.34 54.30 58.69 59.48 46.99 39.32 80 22.15 38.96 42.45 41.75 53.92 56.44 53.55 44.97 37.23 90 19.69 34.58 41.96 40.43 49.69 56.21 48.41 40.29 34.02 100 19.39 23.97 41.32 37.44 48.66 56.07 46.49 36.29 27.10 Table-3 Sewage treatment performance (Before and after treatment) in the Control (Without Colocasia esculentaafter 4 days (96 hrs) HRTs Concentration %pH EC (µMohs/ Cm) TSS (mg /L) TDS (mg /L) TS (mg /L) BOD (mg /L) COD (mg /L) NO(mg /L) PO(mg /L) SO(mg /L) B A B A B A B A B A B A B A B A B A B A 10 7.91 7.62 1.02 0.96 113 106 603 472 716 578 4.60 3.68 14.8 11.36 5.4 4.6 3.60 3.12 28.0 24.7 20 7.68 7.58 1.08 0.99 152 137 660 473 812 610 5.80 4.44 17.4 12.65 6.0 4.9 5.12 4.34 39.0 33.12 30 7.52 7.48 1.16 1.03 157 137 770 529 927 666 6.60 4.86 19.3 12.86 9.5 7.2 8.66 6.87 53.0 42.0 40 7.47 7.42 1.23 1.09 167 140 845 569 1012 709 7.10 4.88 21.8 12.92 11.7 8.9 9.86 7.08 66.0 55.12 50 7.18 7.20 1.29 1.14 172 124 950 672 1122 796 8.07 6.32 24.4 15.76 13.2 10.4 12.41 10.56 78.0 68.0 60 6.09 7.12 1.33 1.19 236 174 998 702 1234 876 9.50 7.56 27.7 18.56 17.0 13.6 14.66 12.78 84.0 74.0 70 6.81 7.14 1.52 1.36 260 198 1122 790 1382 988 13.07 10.56 36.9 25.12 19.6 15.8 16.83 14.08 89.0 79.46 80 6.87 7.21 1.67 1.50 308 266 1220 910 1528 1176 21.04 17.56 41.6 29.46 21.4 18.2 17.92 15.96 94.0 84.12 90 6.76 7.27 1.98 1.79 347 300 1320 996 1667 1296 36.04 31.32 92.8 78.56 24.6 21.2 18.81 16.96 97.0 88.12 100 6.79 7.22 2.63 2.38 392 341 1360 1045 1752 1386 42.0 36.45 118 102 26.8 23.4 21.60 19.84 107.0 99.86 Concentration %pH EC (µMohs/cm) TSS (mg /L) TDS (mg /L) TS (mg /L) BOD (mg /L) COD (mg /L) NO(mg /L) PO(mg /L) SO(mg /L) B A B A B A B A B A B A B A B A B A B A 10 7.91 7.8 1.02 0.94 113 102 603 468 716 570 4.60 3.62 14.8 11.12 5.4 4.1 3.60 2.90 28.0 23.0 20 7.68 7.5 1.08 0.98 152 137 660 467 812 604 5.80 4.38 17.4 12.31 6.0 4.3 5.12 3.98 39.0 31.0 30 7.52 7.4 1.16 1.01 157 140 770 512 927 652 6.60 4.78 19.3 12.76 9.5 6.1 8.66 6.32 53.0 39.0 40 7.47 7.3 1.23 1.04 167 131 845 531 1012 662 7.10 4.92 21.8 13.66 11.7 7.12 9.86 6.86 66.0 46.0 50 7.18 7.2 1.29 1.09 172 121 950 560 1122 681 8.07 5.71 24.4 14.32 13.2 7.22 12.41 7.90 78.0 51.0 60 6.09 7.1 1.33 1.06 236 148 998 550 1234 698 9.50 5.65 27.7 14.62 17.0 7.71 14.66 8.86 84.0 53.0 70 6.81 7.14 1.52 1.16 260 140 1122 560 1382 700 13.07 6.26 36.9 15.24 19.6 7.94 16.83 8.92 89.0 54.0 80 6.87 7.17 1.67 1.30 308 188 1220 702 1528 890 21.04 9.86 41.6 18.12 21.4 9.94 17.92 9.86 94.0 59.0 90 6.76 7.23 1.98 1.59 347 227 1320 766 1667 993 36.04 18.31 92.8 40.63 24.6 12.69 18.81 11.23 97.0 64.0 100 6.79 7.26 2.63 2.12 392 298 1360 798 1752 1096 42.0 21.56 118 51.83 26.8 14.34 21.60 13.76 107.0 78.0 International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(2), 6-14, February (2013) Int. Res. J. Environment Sci. International Science Congress Association 11 Table-4 Percentage reduction in various parameters in the Control Bed (Without plant) after the sewage treatment Sewage Concentrations (%) E.C. in % TSS in % TDS in % TS in % BOD in % COD in % NO3 in % PO4 in % SO4 in % 10 5.88 6.19 21.72 19.27 20.00 23.24 14.81 13.33 11.78 20 8.33 9.86 28.33 24.87 23.44 27.29 18.33 15.23 15.07 30 11.20 12.73 31.29 28.15 26.36 33.36 24.21 20.66 20.75 40 11.38 16.16 32.66 29.94 31.26 39.81 23.93 20.89 16.48 50 11.62 27.90 29.26 29.05 21.68 35.40 21.02 14.90 12.82 60 10.52 26.27 29.65 29.01 20.42 32.99 20.00 12.82 11.90 70 10.52 23.84 29.59 28.50 19.20 31.92 19.38 12.06 10.71 80 10.17 13.63 25.40 23.03 16.53 29.18 14.95 10.93 10.51 90 9.59 13.54 24.54 22.25 13.09 15.34 13.82 09.83 09.15 100 9.50 13.01 23.16 20.89 13.21 13.55 12.68 09.35 06.67 Table-5 Analysis of soil used in the treatment set up before and after treatment of different beds. Sr. No. Parameters Nursery Soil Before treatment Colocasia esculenta (After treatment) Control bed Or Without plant (After treatment) 1 Nitrate (Kg/Hectare) 264 270 96 2 Phosphorous (Kg/Hectare) 7 12 11 3 Potassium (Kg/Hectare) 531 439 454 4 Calcium (Meq) 1.62 1.63 1.60 5 Magnesium (Meq) 0.48 0.47 0.51 6 Sodium (Meq) 0.35 0.73 0.71 7 pH 7.90 7.70 7.80 8 Salinity (Total Soluble Salts) 0.84 1.32 1.00 9 Free Lime (%) 2.64 2.34 3.33 10 Density of Soil (g /cm 3 ) 1.09 1.31 1.16 11 Organic Carbon (%) 0.44 0.45 0.16  \n \n  \r\n\n   \nReduction in various parameters using Colocasia esculenta \r     \r    Figure-7 Reduction in various parameters using Colocasia esculenta International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(2), 6-14, February (2013) Int. Res. J. Environment Sci. International Science Congress Association 12  \n \n  \r\n\n   \n \n\n \n\n\n \n\n \n\n\n  \r     \r    Figure-8 Reduction Efficiency of various parameters in the Control Bed (Without plant). The colour and odour were removed and hence treated samples were observed clear and odorless. The average wastewater pH values obtained in the plant bed for the inlet and outlet of Angular- HSSF- CW were 6.79 to 7.26 and in the control bed 6.79 to 7.22 respectively. This increase of pH value may be due to formation of some acidic components in the bioremediation process. In our earlier study, a similar trend in pH value was observed at same rate of HRT14. Other authors also have reported the decreasing trend in pH in the lake water by using various aquatic macrophytes29, 30, 31 and also noticed the average colour removal from pulp and paper mill wastewater through HSSF-CW. It was by 97% and the change in pH at decreasing mode while some of them reported the change in pH in decreasing mode in his field scale study of domestic wastewater using Phragmites karka32. The maximum EC reduced was by 23.68%, TSS were reduced by 46.15%, TDS were reduced by 50.08%, TS were reduced by 49.34%, BOD was reduced by 54.30%, and COD was reduced by 58.69%. The COD removal is believed to occur rapidly through settling and entrapment of particulate organic matter in the void spaces of the substrate33. The substrate is the main supporting material for plants and microbial growth. Fine gravel promotes higher growth of plants and therefore increases the quantity of contaminant removal34. The microorganisms attached to the root zone of the plants play a very important role in the degradation of organic matter. They play crucial role in the conversion of organic carbon to carbon dioxide. In this process, the oxygen is supplied by the roots of the plants35. Soluble organic matter may also be removed by number of separation processes including absorption and adsorption. The degree of sorption and its rate are dependent on the characteristics of both organic and the solid surface36. The maximum NO was reduced by 59.48%, PO was reduced by 46.99% and SO was reduced by 39.32% respectively in present study. These pollutants were reduced due to reed bed of Colocasia esculenta. In addition to this, phyto-volatilization is also an important phenomenon for the removal of pollutants from the CW. Some wetland plants also take up pollutants directly through the root transport system and transfer them to the atmosphere via their transpiration system 37, 38, 39..In the reference or control set (without plant), the maximum pollution reduction efficiency was observed at 40% and 50% sewage concentration. The maximum EC reduced was by 11.62%, TSS were reduced by 27.90%, TDS were reduced by 29.65%, TS were reduced by 29.94%, BOD was reduced by 31.26%, COD was reduced by 39.81%, NO was reduced by 24.21%, PO was reduced by 20.89% and SO was reduced by 20.75% respectively. These pollutants were reduced in the reference set due to trickling process and biofilm of aerobic and anaerobic microorganism. The difference in the efficiency of each parameter in both sets indicates that the use of Colocasia esculenta is helpful for better treatment of sewage at almost all concentrations studied as compared to reference set. As a result, the treatment efficiency is higher at 70% concentration of sewage, in experimental test set with Colocasia esculenta over the reference or control set without Colocasia esculenta. The results obtained by the analysis of soil indicate that the concentration of macro and micro nutrients were maximum in treated sets over the control bed (without plant) than nursery soil of before treatment and Colocasia esculenta treated bed of CW. This increase of nutrients levels in the soil was due to continuous addition of concentration of sewage for the pollution reduction efficiency study. Conclusion Angular Horizontal Subsurface Flow Constructed wetland through phytoremediation is an effective green technology for International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(2), 6-14, February (2013) Int. Res. J. Environment Sci. International Science Congress Association 13 the treatment of sewage. The proper selection of locally adaptive aquatic plant is more trust worthy and insured technology for better treatment of sewage in local environment. The difference in the efficiency of each parameter in both sets indicated that the use of Colocasia esculenta is helpful for better treatment of sewage at almost all concentrations as compared to reference or control set of CW. The pollution reduction efficiency is higher up to 70% dilution factor in experimental test set with Colocasia esculenta than the reference or control set (without plant). It is concluded that Colocasia esculenta is capable and suitable plant for the treatment of city sewage. This plant is a mostly adaptive in western region of India. It has considerable capacity of pollution reduction and generating treated water which is useful for some common uses like gardening, washing, irrigation and general uses like toilet flushing, cooling, floor washing and cleaning applications in both, households and industries. References 1.Oluseyi E. 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