Hybrid reactor for priority pollutant-trichloroethylene removal

The present study was initiated to explore the potential of a hybrid biolog ical reactor, combining trickling filter (TF) and activated sludge process (ASP), to treat wastewater containing trichloroethylene (TCE) at ambient te mperature at different hydraulic retention time (HRT). The biofilm acclimat ion was achieved in 55-60 days with gradual increase in TCE concentration f rom 1 mg/l to 100 mg/l with a parallel increase in the concentration of sub strate sodium acetate and other nutrients. COD and TCE concentration were t aken as prime parameters for monitoring the growth of biofilm. During accli mation COD removal varied beta een 54.6-97.5% while TCE was removed 72.6-99 .9%. HRT study was performed after acclimation. The removal efficiency incr eased with decreasing flow rate with maximum TCE removal (99.99%) at 6 l/d corresponding to an HRT of 28 h (TF 18 h+ASP 10 h). This was followed by a C:N:P ratio study. A ratio of 100:20:1 led to the sustenance of maximum TCE removal. h Maximum TCE removal (99.99%) was observed at a substrate: cosub strate ratio of 100:1. A pH of 7.4 +/- 0.2 was found to be optimum for degr adation. Finally, volatilization losses were estimated to be 18.5%. A mass balance gave an efficiency of 81.51% for biological removal of TCE. (C) 200 0 Elsevier Science Ltd. All rights reserved.