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

Abstract

Abstract Thiobencarb is an 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 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 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 d–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 d–1 at the sixth operation period. Moreover, COD removal efficiencies were more than 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.