Estimation of Chlorinated Aliphatics Critical Loading Rates for Anaerobic Wastewater Treatments

Abstract

Anaerobic reactors have considerable potential of biotransforming priority pollutantsfrom industrial wastewaters. With proper acclimation, selected chlorinated aliphatics were transformed simultaneously with acetic acid or propionic acid at significant rates. Based on fate model estimation. Biotransformation, accounted for from 67% to 99% of the total removal, was the major mechanism of chlorinated aliphatics removal; while volatilization, ranged from 0.2% to 33% of removal, was the secondary one for reactors supplied with either HPr or HAc. The critical loading rate was defined as the loading rate of a specific chlorinated aliphatic which resulted in reduction of the primary substrate utilization to 50%. The chlorinated aliphatics critical loading rates for the microbes metabolizing HPr were from 0.4 to 24 mg/g cell-day, while those rates for the microbes metabolizing HAc ranged from 0.1 to 21 mg/g cell-day. On the other hand, anaerobic microorganisms biotransformed chlorinated aliphatic alkenes at a higher rate than those of alkanes. Under the critical loading, an anaerobic wastewater treatment process could stably and simultaneously biotransform primary substrate along with chlorinated aliphatics.