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

Industrial waste as novel conductive mediator was applied for wastewater treatment as a novel strategy for both waste recycling and sustainable development of wastewater treatment. In this study, nanoscale zero valent iron-loaded fly ash-based activated carbon (nZVI@FABAC) was prepared and applied to enhancing activated sludge (AS) process for coal chemical wastewater (CCW) treatment. The results demonstrated that the removal efficiencies of COD and total phenols (TPh) in nZVI@FABAC/AS process reached about 83.96 and 85.17%, which increased 52.51 and 31.52% compared with the single AS process, respectively. And the acute toxic unit value of CCW was reduced by 88.24% after nZVI@FABAC/AS process treatment. The various functional bacteria including phenol-degrading bacteria (Comamonas and Acinetobacter), electroactive bacteria (Geobacter), and iron reduction bacteria (Geothrix) were enriched in the nZVI@FABAC/AS process, which provided various electron transfer pathways to improve the degradation of toxic organics in CCW. Accordingly, nZVI@FABAC/AS process provided a promising and sustainable way for industrial wastewater treatment.

Keywords: Biotoxicity; Conductive mediator; Enhanced biological treatment; Industrial wastewater; Microbial community.