Performance and microbial metabolic mechanism of imidacloprid removal in a microbial electrolysis cell-integrated adsorption biological coupling system.

Coke used as a filler to treat imidacloprid (IMI) wastewater by both adsorption biological coupling and microbial electrolysis cells (MEC)-adsorption biological coupling technologies, the removal efficiencies on pollutions in wastewater containing IMI were investigated, and the key functional genes related to IMI degradation pathways were also revealed. Results showed that the removal rates of COD, ammonia nitrogen, TP, and IMI under the adsorption biological coupling treatment and MEC-adsorption biological coupling treatment were 94.61-95.54%, 93.37-95.79%, 73.69-83.80%, and 100%, respectively. MEC increased the relative abundance of Proteobacteria by 9.01% and transformed the dominant bacteria from Lysobacter and Reyranella to Brevundimonas and Aquincola. Moreover, MEC up-regulated the abundance of the coding genes PK (9.30%), narG (2.26%), pstS (3.63%), and phnD (1.32%), and converted the IMI degradation products to smaller molecular weight C6H8N2 and C6H6ClNO. This study provided an important reference information for efficient treatment of IMI wastewater using the MEC-adsorption biological coupling technology.

Effects of PFOA on the physicochemical properties of anaerobic granular sludge: Performance evaluation, microbial community and metagenomic analysis.

The impact of perfluorooctanoic acid (PFOA) on the anaerobic granular sludge was evaluated through a sequential batch experiment. Results showed that PFOA inhibited the chemical oxygen demand (COD) removal rate of the sludge and the dosage of 100 mg/L PFOA was more obvious. However, this negative effect would gradually weaken with the adaptation of microorganisms. For the 50 mg/L PFOA experimental group, the proteins content in the extracellular polymeric substances (EPS) of the anaerobic granular sludge increased from 1.53 mg/g to 3.65 mg/g. Meanwhile, PFOA inhibited the 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride (INT) activity of the anaerobic granular sludge. Furthermore, 100 mg/L PFOA reduced the relative abundance of Proteobacteria by 5.99% and Longilinea by 1.11%. 100 mg/L PFOA mainly restricted COD removal by affecting the glycolysis process, with the abundances of glucokinase and pyruvate kinase reduced by 8% and 28.1%, respectively. Compared with the control group, the relative abundance of the methyl-coenzyme M reductase alpha subunit increased by 84%, respectively, under 100 mg/L PFOA.