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Zhang T, Li K, Liu X. DBP-FP change of biofilm in drinking water distribution system induced by sequential UV and chlorine disinfection: Effect of UV dose and influencing mechanism. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 338:122716. [PMID: 37832779 DOI: 10.1016/j.envpol.2023.122716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 09/27/2023] [Accepted: 10/07/2023] [Indexed: 10/15/2023]
Abstract
The issue of biofilm-related disinfection byproducts (DBPs) in drinking water distribution system (DWDS) has garnered significant attention. This study sought to examine the changes in biofilm-originated halogenated DBP formation potential (biofilm DBP-FP) in simulated continuous-flow DWDSs subjected to sequential UV and chlorine disinfection (UV-Cl2) treatments with varying UV doses and to propose the underlying mechanism. The formation potential of trihalomethanes (THMs), haloacetic acids (HAAs), and the total organic halogen (TOX, X = Cl and Br) produced by biofilm were measured. Results showed that the biofilm TOCl-FP was at a minimum with a UV dose of 80 mJ/cm2, corresponding to the lowest amounts of protein and polysaccharides in the extracellular polymeric substances (EPS). Sphingobium, Methylobacterium, and Sphingomonas played a crucial role in protein and polysaccharide biosynthesis. Bacterial community composition characterization together with metabolic function analysis indicated that dominant bacteria varied and metabolic function shifted due to UV-Cl2 disinfection, with Alphaproteobacteria increasing in relative abundance and Bacteroidia showing the opposite trend with increasing UV doses. Correlation analysis suggested that the UV-Cl2 disinfection process led to changes in the water matrix, including organics, inorganics, bacteria, and components that provide environmental pressure for the biofilm. These changes ultimately influenced the properties of the biofilm EPS, which had a direct impact on biofilm DBP-FP.
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Affiliation(s)
- Tuqiao Zhang
- Zhejiang Key Laboratory of Drinking Water Safety and Distribution Technology, Zhejiang University, Hangzhou, 310058, PR China
| | - Kexin Li
- Zhejiang Key Laboratory of Drinking Water Safety and Distribution Technology, Zhejiang University, Hangzhou, 310058, PR China
| | - Xiaowei Liu
- Zhejiang Key Laboratory of Drinking Water Safety and Distribution Technology, Zhejiang University, Hangzhou, 310058, PR China; Ocean College, Zhejiang University, Hangzhou, 310058, PR China.
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Wang Y, Xu H, Yao H, Liu B, Ding M, Lin T, Mo T, Gao L, Zhang L. Insights into the role of prechlorination in algae-laden raw water distribution process: Algal organic matter and microcystin-LR release, extracellular polymeric substances (EPS) aggregation, and pipeline biofilm communities. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130306. [PMID: 36345065 DOI: 10.1016/j.jhazmat.2022.130306] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 10/25/2022] [Accepted: 10/30/2022] [Indexed: 06/16/2023]
Abstract
Prechlorination routinely applied for the treatment of algae-laden raw water has received extensive attention due to its influence on water quality and aquatic microbes. In this study, prechlorination experiments with different doses were conducted in sets of model raw water distribution systems. With the elevated dose of chlorine and prolonged hydraulic retention time (HRT), the ratio of intact algal cells decreased, and the stability of water enhanced. Dissolved organic carbon (DOC) and nitrogen (DON) increased when chlorine dose elevated from 0 to 0.5 mg/L but decreased with elevations from 0.5 to 2.0 mg/L, while UV254 showed a monotonically increasing tendency. DOC, DON and extracellular microcystin-LR increase initially and decrease thereafter with the prolonged HRT. Notably, the effects of prechlorination on extracellular polymeric substances aggregation behavior on pipe walls and microbial community composition was revealed, providing more profound understanding of the community dynamics in this engineered system. This study helped optimize strategies to improve the stability and efficiency of pretreatment of algae-laden water.
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Affiliation(s)
- Yueting Wang
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Hang Xu
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Hao Yao
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Bonan Liu
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Mingmei Ding
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Tao Lin
- Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Tianpei Mo
- Hefei Industry Investment Group, Hefei 230071, PR China.
| | - Li Gao
- South East Water, PO Box 2268, Seaford, VIC 3198, Australia.
| | - Lei Zhang
- School of Civil Engineering & Architecture, Chuzhou University, Chuzhou 230090, PR China.
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Shi X, Clark GG, Huang C, Nguyen TH, Yuan B. Chlorine decay and disinfection by-products formation during chlorination of biofilms formed with simulated drinking water containing corrosion inhibitors. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 815:152763. [PMID: 34990663 DOI: 10.1016/j.scitotenv.2021.152763] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/21/2021] [Accepted: 12/25/2021] [Indexed: 06/14/2023]
Abstract
Corrosion inhibitors used to reduce pipe corrosion can alter the physical structure and biochemical components of the biofilm in premise plumbing systems. We studied the effects of corrosion inhibitors on chlorine decay and associated disinfection by-products (DBPs) formation by biofilms grown with simulated drinking water amended with silicate, phosphate, and the phosphate blends. Experiments were conducted with either intact biofilms or biofilm materials dispersed in solution during sonication (referred to as biomass). While there was no significant difference in chlorine decay among biomass from different biofilms, biomass from the phosphate blend biofilm showed the lowest trihalomethane (THMs) and haloacetic acids (HAAs) formation. The chlorine decay rate constants from the biofilm experiment were ranked as: phosphate blends > phosphate ≈ groundwater (GW) > silicate. The kinetics of chlorine decay and formation of DBPs were successfully described by pseudo-first-order kinetics. These fitting parameters were used to predict the DBPs formation in a realistic premise plumbing system. The results showed that biofilm-derived THMs and HAAs increased with increasing chlorine concentration, while THMs and HAAs first increased and then stabilized to a maximum with increasing biofilm total organic carbon (TOC) concentration. In general, the biofilms grown with phosphate-based corrosion inhibitors resulted in lower DBPs formation yield but higher bacterial release, which could potentially increase the risk of user exposure to opportunistic pathogens in drinking water. The silicate biofilms showed the largest yield coefficient of DBPs formation but had the least biomass and lower bacterial release.
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Affiliation(s)
- Xiaoyang Shi
- Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China
| | - Gemma G Clark
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Conghui Huang
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Thanh H Nguyen
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Baoling Yuan
- Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China.
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Study on the Control of Dichloroacetonitrile Generation by Two-Point Influent Activated Carbon-Quartz Sand Biofilter. MEMBRANES 2022; 12:membranes12020137. [PMID: 35207059 PMCID: PMC8877799 DOI: 10.3390/membranes12020137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 12/10/2022]
Abstract
Aiming at the problem of highly toxic Nitrogenous disinfection by-products (N-DBPs) produced by disinfection in the process of drinking water, two-point influent activated carbon-quartz sand biofilter, activated carbon-quartz sand biofilter, and quartz sand biofilter are selected. This study takes typical N-DBPs Dichloroacetonitrile (DCAN) as the research object and aromatic amino acid Tyrosine (Tyr), an important precursor of DCAN, as the model precursor. By measuring the changes of conventional pollutants in different biofilters, and the changes of Tyr, the output DCAN formation potential of the biofilters, this article investigates the control of DCAN generation of the two-point influent activated carbon-quartz sand biofilter. The results show that the average Tyr removal rate of the three biofilters during steady operation is 73%, 50%, and 20%, respectively, while the average effluent DCAN generation potential removal rate is 78%, 52%, and 23%, respectively. The two-point influent activated carbon-sand biofilter features the highest removal rate. The two-point water intake improves the hypoxia problem of the lower filter material of the activated carbon-quartz sand biofilter, and at the same time, the soluble microbial products produced by microbial metabolism can be reduced by an appropriate carbon sand ratio, which is better than traditional quartz sand filters and activated carbon-quartz sand biofilters in the performance of controlling the precursors of N-DBPs.
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