Reductive dechlorination of 1, 2-dichloroethane using anaerobic sequencing batch reactor (ASBR)

Abstract

The objective of this research was to study the dechlorination of 1,2-dichloroethane (1,2-DCA) in a synthetic wastewater with lab-scale anaerobic sequencing batch (ASBR) reactors. Anaerobic sludge was used as a biocatalyst. Sodium acetate and dextrose served as the main methanogenic substrate. Experimental studies were conducted at wide-range of volumetric (0.25-1.25 g COD/L.d) and specific (0.0362-0.181 g COD/ g VSS.d) loading rates and influent wastewater CODs (500-2500 mg/L). During 266 days of reactor operation, the mixed culture degraded 1,2 dichloroethane at concentrations of up to 50 mg/L, with an HRT of 48 hrs. No chlorinated intermediates or residues were found. 1,2-DCA degradation resulted in ethene and ethane formation. Acetate was the most effective electron donor for dechlorination, although, dextrose was also effective, but to a lesser extent. The mixed culture degraded 1,2 Dichloroethane in the temperature range of 28+/-4 degrees C, with the pH range of 7.25 to 7.95. The 1,2-DCA removal rates achieved, and the safe nature of the end products, signify the anaerobic sequencing batch (ASBR) reactor technology for practical decontamination of waters containing such types of organochlorines. The COD removal efficiencies were in the range of 95 to 98% depending on volumetric and specific loading rates applied.