Effect of Carbon Source on PCE Dehalogenation

A laboratory study using the upflow anaerobic sludge blanket reactor for treating highstrength wastewater containing tetrachloroethene (PCE) was carried out to study the effect of carbon source, recycle, and shock loading on dehalogenation of PCE and process performance. The PCE was dehalogenated to trichloroethylene, cis-1,2dichloroethylene, vinyl chloride, and ethylene. During the study on the effect of carbon source, the PCE and COD removal up to 97% and biogas production of 0.518-0.47 m3/kg CODrem with methane content up to 66% were achieved under steady-state operating conditions. An increase in the influent COD from 2,000 to 4,000 mg/L did not show any improvement in the PCE removal. Recycling of effluent at 50% showed the decrease in COD removal and increase in the effluent concentration of dichloroethylene and vinyl chlorides. Around 1-3.5% of influent PCE stripping to biogas was observed. It was observed that methanol has the stimulatory effect on the dehalogenation of PCE. A shock loading study showed that the upflow anaerobic sludge blanket reactor could assimilate 1.5-2 times the original PCE concentration (50 mg/L) without much effect on the process performance.