Bioremediation of carbendazim and thiamethoxam in domestic greywater using a bioaugmented microbial consortium

Abstract

The safe and effective removal of pesticides remaining in environmental media such as greywater is important because of their potential hazard. In this study, the feasibility of a bioremediation approach has been studied against two pesticides (i.e., carbendazim and thiamethoxam) based on three microbial formulations: (1) a fungus culture, (2) an isolated microbial consortium, and (3) an augmented microbial consortium with fungus. The toxicity of the two pesticides in ground water was assessed in terms of the attenuation factor index and the environmental potential risk indicator for pesticides. The concentrations of each pesticide in greywater matrix were measured using an automated isotope dilution solid phase extraction-liquid chromatography-tandem mass spectrometry. The efficiency of bioaugmented microbial consortium, when assessed for carbendazim and thiamethoxam in terms of the extent of degradation over 10 days, was 94.4 and 93.6%, respectively. Two types of toxicity indicators (i.e., environmental potential risk indicator for pesticides (EPRIP) and attenuation factor index (AFI)) were computed to assess the environmental relevancy of taget pesticides in surface and ground waters. Accordingly, their values for carbendazim (EPRIP of 42.1 and AFI of 1003.4) were higher than those of thiamethoxam (EPRIP of 6.4 and AFI of 1001.2). The bacterial culture augmented with fungus Aspergillus versicolor is thus found to be a promising tool to enhance the removal efficiency of the toxic pesticides present in biosystems. It is expected that this study will help promote the research associated with bioaugmentation for diverse microbial species (e.g., Pseudomonas, Klebsiella species, and Bacillus subtilis) with fungus for enhanced biodegradation processes.