Novel strategy to enhance the biological treatment of coal chemical wastewater by nano-zero valent iron loaded fly ash-based activated carbon assisted activated sludge process

Abstract The study was to explore the performance of nanoscale zero valent iron loaded fly ash-based activated carbon (nZVI@FABAC) enhanced activated sludge (AS) process for the removal of toxic organic compounds in coal chemical wastewater (CCW). The results demonstrated that the removal efficiencies of COD and TPh in nZVI@FABAC/AS process reached about 83.96% and 85.17%, respectively, which were significantly increased compared with the single AS process. And the acute toxic units value of CCW was effectively reduced by 88.24% after nZVI@FBAC/AS process treatment. Microbial community analysis revealed that nZVI@FBAC might stimulate the AS system to enrich the various functional bacteria including phenol degrading bacteria (Comamonas and Acinetobacter), electroactive bacteria (Geobacter) and iron reduction bacteria (Geothrix), which provided various electron transfer pathways and facilitated the interspecies cooperation of different bacteria for improving degradation of toxic organic compounds in CCW. From the engineering, economic, environmental perspective, the nZVI@FBAC/AS process has a promising application for industrial wastewater treatment.