Development of ecofriendly hybrid model for wastewater treatment
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Date
2018-08
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Present study envisaged about the phytoremediation of domestic wastewater using floating raft based ecofriendly hybrid model at GBPUA&T, Pantnagar campus premises. Domestic wastewater used in this experiment was slightly alkaline in nature with average pH value of 7.3 with the EC of 624.1 μS/cm. The average concentration of TS, TSS and TDS were found to be 767.62, 527.12 and 244.5 ppm, respectively. BOD and COD of wastewater were 64.75 and 277.25 ppm, respectively. Major nutrients i.e., nitrate nitrogen, ammonical nitrogen, total nitrogen, phosphate and potassium were 11.44, 12.73, 25.73, 11.03 and 11.5 ppm, respectively. While sodium was 25.67 ppm. Among different parameters TSS, BOD, COD, phosphate and nitrate nitrogen were found beyond their discharge permissible limits as per the EPA Rules 1986. Both Canna and Pistia were examined first at lab level experiment to standardize the system for phytoremediation of domestic wastewater in floating rafts and constructed wetland as well as validated the system at laboratory scale before field level study. Where both plants were showed good efficiency to remove various pollutants from the wastewater, moreover in the present experiment Canna plant was more superior as compared to Pistia. Among various models developed for wastewater treatment the hybrid system-1 (HS-1) which was combined with two floating raft tanks such as floating raft tank-I planted with Canna and floating raft tank-II planted with Water lily was found the most efficient and ecofriendly in nature for maximum reduction of various pollutants from the wastewater. After 48 h HRTs the remaining concentration of pollutants such as pH, EC, K, Na, TS, TDS, TSS, BOD, COD, PO4 -1, NH4 +-N, NO3 --N and TN were 7.1, 490, 3, 6, 262, 180, 82, 14, 80, 2.1, 3.18, 3.36 and 8.35 ppm, respectively with their percentage reduction by 5.33, 20.98, 71.43, 77.25, 66.00, 65.19, 67.65, 78.71, 71.56, 79.06, 76.84, 73.08 and 71.79 %, respectively. After this treatment those parameters were beyond their discharge permissible limits were reduced within the permissible limits. The trend of biomass production by Canna and Pistia was inversely proportional as the concentration of cadmium, chromium and lead was increased from 5 to 150 ppm. When the concentration of these heavy metals was beyond the 100 ppm both the plants died due to phytotoxicity. Maximum concentration of Cd, Cr and Pb such as 58.69, 35.61 and 67.77 ppm, respectively were found in root of Canna and 10.13, 6.22 and 15.74, respectively in shoot of Canna which were higher as compared to these metals concentration in the root and shoot of Pistia.
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