Effects of phosphate addition on the removal of disinfection by-product formation potentials by biological activated carbon filtration

Feifei Wang; Yulin Hu; Jiazheng Pan; Jie Zhou; Chiquan He; J A M H Hofman; Wenhai Chu; Jan Peter van der Hoek

doi:10.1016/j.scitotenv.2023.163534

Effects of phosphate addition on the removal of disinfection by-product formation potentials by biological activated carbon filtration

Sci Total Environ. 2023 Jul 15:882:163534. doi: 10.1016/j.scitotenv.2023.163534. Epub 2023 Apr 20.

Authors

Feifei Wang¹, Yulin Hu², Jiazheng Pan², Jie Zhou², Chiquan He², J A M H Hofman³, Wenhai Chu⁴, Jan Peter van der Hoek⁵

Affiliations

¹ School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China. Electronic address: feifeiwang@shu.edu.cn.
² School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China.
³ Water Innovation and Research Centre, Department of Chemical Engineering, University of Bath, Bath BA2 7AY, UK.
⁴ State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. Electronic address: 1world1water@tongji.edu.cn.
⁵ Department of Water Management, Delft University of Technology, Delft, 2628 CN, Netherlands; Research & Innovation Program, Waternet, Amsterdam, 1069 AC, Netherlands.

PMID: 37086988
DOI: 10.1016/j.scitotenv.2023.163534

Abstract

In drinking water treatment plants (DWTPs), the widely used biological activated carbon filters (BACFs), as the last barrier before disinfection, can remove dissolved organic matter (DOM) known as precursors of disinfection by-products (DBPs). Whether phosphate addition can improve water purification and DBP control of BACFs is still controversial. This study investigated short-term and long-term effects of phosphate addition on controlling DBP formation potentials (FPs) by BACFs via column and batch experiments. The BAC columns presented good water purification performance: they removed around 50 % DOM, nearly all fulvic acid-likes and humic acid-likes as well as 5 %-70 % chlor(am)innated THM₄, HAA₉ and HAN₄ FPs (except chloraminated THM₄ FPs)， which was mainly contributed by aerobic bacteria not anoxic bacteria. Phosphate addition within 7-14 days further improved removals of DOM, aromatic organics, fluorescence fractions in DOM as well as HAA₉ and HAN₄ FPs (especially TCAA FP and TCAN FP) to different extent. However, this improvement did not last longer, and removals of DOM, aromatic organics, two fluorescence fractions (soluble microbial byproduct-likes and humic acid-likes) and DBP FPs decreased despite long-term phosphate addition. Oxic and anoxic batch experiments showed that the positive response of water purification to short-term phosphate addition was also mainly attributed to aerobic bacteria and not to anoxic bacteria. For example, the former decreased DOM and DBP FPs, while the latter increased protein- and tryptophan-like substances as well as chloraminated THM₄ FPs. Phosphate addition resulted in EPS increase in anoxic reactors and decrease in oxic reactors. These results indicated that a high dissolved oxygen in BACFs may be helpful for water purification and DBP control. Overall, short-term phosphate addition into phosphorus-limited water is beneficial for BACFs to control DBPs while long-term addition has no effect. Therefore, an intermittent phosphate addition into BACFs is suggested to control DBPs in DWTPs.

Keywords: Anoxic condition; Chloramination; Chlorination; Disinfection by-products; Oxic condition; Phosphate.

MeSH terms

Charcoal
Disinfectants*
Disinfection / methods
Halogenation
Humic Substances
Phosphates
Water Pollutants, Chemical* / analysis
Water Purification* / methods

Substances

Charcoal
Phosphates
Humic Substances
Water Pollutants, Chemical
Disinfectants