Potassium ferrate combined with ultrafiltration for treating secondary effluent: Efficient removal of antibiotic resistance genes and membrane fouling alleviation

Boxuan Yang; Qinxue Wen; Zhiqiang Chen; Yingcai Tang

doi:10.1016/j.watres.2022.118374

Potassium ferrate combined with ultrafiltration for treating secondary effluent: Efficient removal of antibiotic resistance genes and membrane fouling alleviation

Water Res. 2022 Jun 15:217:118374. doi: 10.1016/j.watres.2022.118374. Epub 2022 Mar 31.

Authors

Boxuan Yang¹, Qinxue Wen¹, Zhiqiang Chen², Yingcai Tang¹

Affiliations

¹ State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China.
² State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China. Electronic address: czqhit@hit.edu.cn.

PMID: 35398806
DOI: 10.1016/j.watres.2022.118374

Abstract

Antibiotic resistance genes (ARGs) are considered as emerging environmental contaminants, which should be controlled by wastewater treatment plants to prevent their discharge into the environment. However, conventional treatment techniques generally fail to successfully reduce ARGs, and the release of cell-free ARGs was underestimated. In this study, potassium ferrate (Fe(VI)) pretreatment combined with ultrafiltration (UF) process was developed to remove both cell-associated and cell-free ARGs in real secondary effluent, compared to ferric chloride (Fe(III)) and poly-aluminum chloride (PACl) pretreatment processes. It was found that total ARGs especially cell-free ARGs were effectively removed by Fe(VI) oxidation. However, due to the poor settleability of the negatively charged particles formed by Fe(VI) in the secondary effluent, the removal of cell-associated ARGs was less compared to Fe(III) and PACl pretreatments. The combination of Fe(VI) and UF removed the most ARGs (3.26 - 5.01 logs) due to the efficient removal of cell-free ARGs by Fe(VI) (> 2.15 logs) and co-interception of both cell-associated ARGs and Fe(VI) formed particles of the UF. High-throughput sequencing revealed that Fe(VI) decreased the viability and relative abundances of the potential ARGs hosts. Fe(VI)-UF exhibited the best performance on humic-like fluorescent organic matters removal, as well as the least phytotoxicity in the effluent. Moreover, membrane fouling was remarkably alleviated by Fe(VI) pretreatment because (1) Fe(VI) removed macromolecules such as protein-like and polysaccharide-like substances which would block the membrane pores, (2) Fe(VI) improved the hydrophilicity of foulants and reduced the hydrophobic adsorption between foulants and membrane. In short, Fe(VI)-UF is a promising technology to efficiently remove ARGs (especially cell-free ARGs) and alleviate UF membrane fouling in wastewater reclamation.

Keywords: Antibiotic resistance genes (ARGs); Coagulation; Potassium ferrate; Ultrafiltration; Wastewater reclamation.

MeSH terms

Anti-Bacterial Agents / pharmacology
Drug Resistance, Microbial / genetics
Ferric Compounds
Iron Compounds
Membranes, Artificial
Potassium Compounds
Ultrafiltration* / methods
Water Purification* / methods

Substances

Anti-Bacterial Agents
Ferric Compounds
Iron Compounds
Membranes, Artificial
Potassium Compounds
potassium ferrate