Biodegradation of ethylthionocarbamates by a mixed culture of iron-reducing bacteria enriched from tailings dam sediments

Abstract

Ethylthionocarbamates (ETC), which is the most widely used as collectors in the flotation of sulfide, is known to cause serious pollution to soil and groundwater. The potential biodegradation of ETC was evaluated by applying a mixed culture of iron-reducing bacteria (IRB) enriched from tailings dam sediments. The results showed that ETC can be degraded by IRB coupled to Fe(III) reduction, both of which can be increased in the presence of anthraquinone-2,6-disulfonate (AQDS). Moreover, Fe(III)-EDTA was found to be a more favorable terminal electron acceptor compared to α-Fe2O3, e.g., within 30 d, 72% of ETC was degraded when α-Fe2O3+AQDS was applied, while it is 82.67% when Fe(III)-EDTA+AQDS is added. The dynamic models indicated that the kETC degradation was decreased in the order of Fe(III)-EDTA+AQDS>α-Fe2O3+AQDS>Fe(III)-EDTA>α-Fe2O3, with the corresponding maximum biodegradation rates being 2.6, 2.45, 2.4 and 2.0 mg/(L.d), respectively, and positive parallel correlations could be observed between kFe(III) and kETC. These findings demonstrate that IRB has a good application prospect in flotation wastewater.