Biodegradation of 1,1,2,2-tetrachloroethane in Upflow Anaerobic Sludge Blanket (UASB) reactor

Abstract

This study examines the performance of bench-scale Upflow Anaerobic Sludge Blanket (UASB) reactor in treating simulated wastewaters containing 1,1,2,2-tetrachloroethane (TeCA). Reactors R1 (control) and R2 (containing TeCA) were operated at Hydraulic Retention Times (HRTs) of 36, 30, 24, 18 and 12 h. The removal of TeCA decreased from 99.85% to 98.40% as the HRT was lowered down from 36 to 12 h. The maximum TeCA dechlorination rate and the half velocity coefficient were 0.2 d −1 and 18.58 mg TeCA/l, respectively. The Organic Loading Rate (OLR) was varied from 1.5 to 3.1 kg/m 3/d to yield various substrate:co-substrate ratios and the overall removal of TeCA throughout this study was more than 99%. The average effluent TeCA concentration at optimum HRT (24 h) and substrate:co-substrate ratio (100:1) was less than 0.1 mg/l. The granules within the reactor were 0.1–3.2 mm in size with a heterogeneous bacterial population.