Treatment of coking wastewater by a novel full-scale microaerobic-anoxic-oxic (M/A/O) system: Performance and microbial community analysis.

Abstract

The aim of this study was to investigate the relationship between system removal performance and microbial community structure in a novel full-scale microaerobic-anoxic-oxic (M/A/O) system for coking wastewater (CWW) treatment. The results showed that 93% of chemical oxygen demand (COD) and 99% of NH4+-N removal efficiency were achieved via M/A/O process, meanwhile, main organic pollutants in CWW including phenolic compounds, heterocyclic compounds and polycyclic aromatic hydrocarbons were basically removed. Four dominant phyla of Proteobacteria, Firmicutes, Bacteroidetes and Nitrospirae were demonstrated distributed in the system and played significant roles in M/A/O biological treatment process. Major function of the microaerobic process was to partly remove the biodegradable substances such as phenols and hydrolyze the refractory contaminants such as N-heterocyclic compounds to improve the biological oxygen demand/chemical oxygen demand (BOD5/COD) ratio and release ammonia. This work illustrated the structure and function of microbial community in M/A/O system and provided a new choice for high-strength CWW treatment.