Full-scale evaluation of reversed A2/O process for removal of multiple pollutants in sewage

Abstract

This study evaluated the removal of multiple pollutants, i.e., polybrominated diphenyl ethers (PBDEs), novel halogenated flame retardants (HFRs), sulfonamide antibiotics (SAs), and heavy metals (HMs), by a full-scale reversed A2/O process in a sewage treatment plant (STP) in Guangzhou, China. The reversed A2/O process demonstrated high removal efficiencies (REs) for total PBDEs (60.5% ± 4.3%), novel HFRs (98.4% ± 2.8%) and HMs (70.1% ± 1.2%), and a relatively low RE for SAs (25.0% ± 2.3%). BDE 209, the dominant PBDE congener, showed a high residual concentration (13.41 ± 5.18 ng/L) in the suspended particulate matter (SPM) of treated effluents. Some novel HFRs, dechlorane plus (DP) and decabromodiphenyl ethane (DBDPE), were detected in the SPM of the raw sewage (7.50 ± 4.14 ng/L and 11.52 ± 11.65 ng/L, respectively). The removal of SAs was mainly through biodegradation in the activated sludge bioreactors (ASBs). Of the HMs, Mn and Ni exhibited the lowest REs (47.5% ± 2.2% and 35.0% ± 2.6%, respectively), while Cr and Cu showed the highest removal (REs > 80%). In terms of treatment units in the reversed A2/O process, ASBs showed the highest RE (27.8%) for the multiple pollutants. The information can aid in our understanding of removal properties of STPs on various pollutants and evaluating the ecological/health risks of STPs as point pollutant sources