Performance and microbial characteristics of anaerobic/anoxic/aerobic (A2O)-biofilm system for electroplating wastewater treatment: a pilot scale study

Abstract

A pilot scale study was conducted to explore the performance and microbial characteristics of anaerobic/anoxic/aerobic (A2O)-biofilm system in electroplating wastewater treatment. The results showed that the A2O-biofilm system had a good removal performance for organics, nitrogen and phosphorus in electroplating wastewater, and the average concentrations of chemical oxygen demand, total phosphorus, and total nitrogen reached 28, 0.27, and 10 mg/L. High throughput sequencing showed that electroplating wastewater resulted in the microbial richness and diversity significantly decreased. Proteobacteria and Bacteroides were the dominant phyla in the biofilm process, while the abundance of Chloroflexi and Planctomycetes demonstrated a significant increase in the middle and later stages of biofilm formative process. At the genus level, Nitrosospira, Zoogloea and Haliangium were the dominant genera, among which Nitrosospira significantly increased. Aerobic chemoheterotrophy was always in the lead position which was a main metabolic function. What's more, aerobic nitrite oxidation, nitrification, aerobic chemoheterotrophy and mark iron oxidation were significantly higher in the late stage than those in the early stage.