Synergistic degradation on aromatic cyclic organics of coal pyrolysis wastewater by lignite activated coke-active sludge process

In current study, the degradation of aromatic cyclic organics (ACOs) of coal pyrolysis wastewater (CPW) by lignite activated coke-active sludge (LAC-AS) process was investigated through the insight into synergistic effect of LAC and microbial community. As a contrast, the study on single AS process revealed that high phenols (>200 mg·L⁻¹) exerted irreversible toxicity by eliminating biomass. Meanwhile, quinoline and naphthalene exhibited joint inhibition with phenols on bio-community. Absence of functional genus and insufficient interspecific cooperation caused interrupted biological reaction, leading to degenerated ecosystem and vicious circle. However, LAC-AS performed synergistic degradation of ACOs, leading to developed ecosystems and benign substance metabolisms. Specifically, LAC alleviated toxicity on suspended AS by ACOs adsorption, and the facultative bacteria enriched by LAC exerted synergistic degradation in biochemical processes. Firstly, the bacteria on biofilm facilitated direct interspecies electron transfer for ring-cleavage reaction, and electroactive bacteria (Cloacibacterium, Hydrogenophaga and Stenotrophomonas) were critical for the process. Secondly, suspended AS further degraded ring-cleavage products, achieving the interspecific cooperation with biofilm. The synergistic nitrogen metabolism by different paths also contributed to the benign metabolic circulation.