Enhanced anaerobic degradation of thiobencarb using a horizontal-flow anaerobic immobilized biomass bioreactor.

Abstract

Thiobencarb is a herbicide globally used in the agricultural sector, and its extensive application leads to severe environmental pollution. In this study, the thiobencarb supplementation caused a significant shift in the bacterial community in the sediment slurry. An analysis of the degradation metabolites of microorganisms from the sediment indicated that deschlorothiobencarb, S-4-chlorobenzyl ethylthiocarbamate, 4-chlorobenzyl mercaptan, 4-chlorobenzyl alcohol, 4-chlorobenzoic acid and chlorobenzene were the main intermediates. The degradation rates were significantly enhanced using a horizontal-flow anaerobic reactor with immobilized cells in polyurethane foam. The degradation rates at 2.6, 12.9 and 25.6 mg L-1 concentrations by suspended microorganisms from the sediment in the mineral medium supplemented with glucose were 0.085 ± 0.000, 0.383 ± 0.010 and 0.500 ± 0.045 mg day-1, respectively. The corresponding data for degradation in the reactor were 2.54 ± 0.03, 11.69 ± 0.72 and 18.58 ± 1.83 mg day-1 at the sixth operation period. Moreover, COD removal efficiencies were >90% achieved in the reactor. The proposed method facilitates degradation using a horizontal-flow anaerobic immobilized biomass bioreactor. Moreover, this study reveals the degradation of metabolites of thiobencarb under anaerobic conditions.