Exploring organic micropollutant biodegradation under dynamic substrate loading in rapid sand filters

Wang, J., Poursat, B. A.J., Feng, J., de Ridder, D., Zhang, C., van der Wal, A. and Sutton, N. B. (2022) Exploring organic micropollutant biodegradation under dynamic substrate loading in rapid sand filters. Water Research, 221, 118832. (doi: 10.1016/j.watres.2022.118832) (PMID:35949068)

Abstract

Microbial removal of trace organic micropollutants (OMPs) from drinking water sources remains challenging. Nitrifying and heterotrophic bacteria in rapid sand filters (RSFs) are capable of biodegrading OMPs while growing on ammonia and dissolved organic matter (DOM). The loading patterns of ammonia and DOM may therefore affect microbial activities as well as OMP biodegradation. So far, there is very limited information on the effect of substrate loading on OMP biodegradation at environmentally relevant concentrations (∼ 1 µg/L) in RSFs. We investigated the biodegradation rates of 16 OMPs at various substrate loading rates and/or empty bed contact times (EBCT). The presence of DOM improved the biodegradation of paracetamol (41.8%) by functioning as supplementary carbon source for the heterotrophic degrader, while hindering the biodegradation of 2,4-D, mecoprop and benzotriazole due to substrate competition. Lower loading ratios of DOM/benzotriazole benefited benzotriazole biodegradation by reducing substrate competition. Higher ammonia loading rates enhanced benzotriazole removal by stimulating nitrification-based co-metabolism. However, stimulating nitrification inhibited heterotrophic activity, which in turn inhibited the biodegradation of paracetamol, 2,4-D and mecoprop. A longer EBCT promoted metformin biodegradation as it is a slowly biodegradable compound, but suppressed the biodegradation of paracetamol and benzotriazole due to limited substrate supply. Therefore, the optimal substrate loading pattern is contingent on the type of OMP, which can be chosen based on the priority compounds in practice. The overall results contribute to understanding OMP biodegradation mechanisms at trace concentrations and offer a step towards enhancing microbial removal of OMPs from drinking water by optimally using RSFs.

• Item Type: Articles
• Additional Information: The authors are sincerely thankful to Evides Water Company N.V. and China Scholarship Council (CSC, File No. 201804910659) for financial support.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Poursat, Dr Baptiste

Creator Roles

Poursat, B.: Formal analysis, Supervision, Writing – review and editing

• Authors: Wang, J., Poursat, B. A.J., Feng, J., de Ridder, D., Zhang, C., van der Wal, A., and Sutton, N. B.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: Water Research
• Publisher: Elsevier
• ISSN: 0043-1354
• ISSN (Online): 1879-2448
• Published Online: 07 July 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Water Research 221: 118832
• Publisher Policy: Reproduced under a Creative Commons licence