Performance and microbial community dynamics relationship within a step-feed anoxic/oxic/anoxic/oxic process (SF-A/O/A/O) for coking wastewater treatment

A step-feed anoxic/oxic/anoxic/oxic (SF-A/O/A/O) was developed and successfully applied to full-scale coking wastewater treatment. The performance and microbial community were evaluated and systematically compared with the anoxic/oxic/oxic (A/O/O) process. SF-A/OA/O process exhibited efficient removal of COD, NH4+-N, TN, phenols, and cyanide with corresponding average effluent concentrations of 317.9, 1.8, 46.2, 1.1, and 0.2 mg.L-1, respectively. In particular, the TN removal efficiency of A/O/O process was only 7.8%, with an effluent concentration of 300.6 mg.L-1. Furthermore, polycyclic aromatic hydrocarbons with high molecular weight were the dominant compounds in raw coking wastewater, which were degraded to a greater extent in SF-A/OA/O. The abundance in Thiobacillus, SM1A02, and Thauera could be the main reason why SF-A/O/A/O was superior to A/O/O in treating TN. The microbial community structure of SF-A/O/A/O was similar among stages in system (P >= 0.05, Welch's t-test) and was less affected by environmental factors, which may have been one of the important factors in the system's strong stability. (C) 2021 Published by Elsevier B.V.

Automated summary

The SF-A/OA/O process has demonstrated superior performance in full-scale coking wastewater treatment compared to the A/O/O process, showing efficient removal of COD, NH4+-N, TN, phenols, and cyanide. The abundance and structure of the microbial community may be key factors contributing to the strong stability of the SF-A/OA/O system.