Reinforcement of Magnetotactic Bacteria in Refractory Pollutants Removal, Methane Yield and Enzyme Activities in Anaerobic Membrane Bioreactor for Organic Sulfur Pesticides Wastewater Treatment

Abstract

This study is focused on removing refractory pollutants (mancozeb and ethylenethiourea) and heavy metals of organic sulfur pesticides wastewater by coupling magnetotactic bacteria (MTB) and anaerobic membrane bioreactor (AnMBR) at flow rates 0.9×10-3 m3/d, 1.1×10-3 m3/d, 1.5×10-3 m3/d and 2.2×10-3 m3/d. Results demonstrated that MTB-AnMBR (R2) maximum effluent mancozeb (Mz) concentration was reduced by 55.3% compared with the traditional AnMBR with non-MTB (R1). The average ethylenethiourea (ETU) removals of R2 and R1 were 73.01 ± 2.54% and 48.82 ± 6.17%, respectively. Mn2+ average removal of R2 was 73.65 ± 8.41% (54.00 ± 10.60% of R1) and Zn2+ maximum removal achieved 99.03% (75.69% of R1). Protease, α-glucosidase, dehydrogenase (DHA), acetate kinase (ACK) and coenzyme F420 activity of R2/R1 was 205.4%, 130.5%, 419.6%, 169.6% and 128.8%. COD removal of R2 was 2.1% higher than R1. Additionally, R2 produced more 544 mL/d biogas than R1 (3425 mL/d), specific methane yield (SMY) and specific methane activity (SMA) of R2 were 15.5% and 13.2% higher than those of R1. Finally, the relationships between refractory pollutants concentration, enzyme activity, COD removal and methanogenesis were determined, and the mechanism by which MTB enhance AnMBR was analysed.

Keywords: Magnetotactic bacteria (MTB), Anaerobic membrane bioreactor (AnMBR), Organic sulfur pesticides wastewater, Refractory pollutants, Enzyme activities