Formation and control of C- and N-DBPs during disinfection of filter backwash and sedimentation sludge water in drinking water treatment

WATER RESEARCH

卷:194

Article

Qian, Yunkun¹  Chen, Yanan¹  Hu, Yue¹  Hanigan, David²  Westerhoff, Paul³  An, Dong^1,4 

[1] Fudan Univ, Dept Environm Sci & Engn, Shanghai 200238, Peoples R China

[2] Arizona State Univ, Sch Sustainable Engn & Built Environm, Ira A Fulton Sch Engn, Tempe, AZ 85287 USA

[3] Univ Nevada, Dept Civil & Environm Engn, Reno, NV 89557 USA

[4] Shanghai Inst Pollut Control & Ecol Secur, Shanghai 200092, Peoples R China

关键词: disinfection byproducts;    Filter backwash water;    sedimentation sludge water;    Calculated toxicity;   

DOI  :  10.1016/j.watres.2021.116964

来源: Elsevier

【 摘 要 】

Drinking water treatment plants (DWTPs) produce filter backwash water (FBW) and sedimentation sludge water (SSW) that may be partially recycled to the head of DWTPs. The impacts of key disinfection conditions, water quality parameters (e.g., disinfection times, disinfectant types and doses, and pH values), and bromide concentration on controlling the formation of trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and haloacetamides (HAMs) during disinfection of FBW and SSW were investigated. Concentrations of most disinfection byproducts (DBPs) and associated calculated toxicity increased with extended chlorination for both FBW and SSW. During chlorination of both FBW and SSW, elevated chlorine doses significantly increased THM yields per unit dissolved organic carbon (DOC), but decreased HAN and HAM yields, with minimum effect on HAA yields. Chloramine disinfection effectively inhibited C-DBP formation but promoted N-DBPs yields, which increased with chloramine dose. Calculated toxicities after chloramination increased with chloramine dose, which was opposite to the trend found after free chlorine addition. An examination of pH effects demonstrated that C-DBPs were more readily generated at alkaline pH (pH= 8), while acidic conditions (pH = 6) favored N-DBP formation. Total DBP concentrations increased at higher pH levels, but calculated DBP toxicity deceased due to lower HAN and HAM concentrations. Addition of bromide markedly increased bromo-THM and bromo-HAN formation, which are more cytotoxic than chlorinated analogues, but had little impact on the formation of HAAs and HAMs. Bromide incorporation factors (BIFs) for THMs and HANs from both water samples all significantly increased as bromide concentrations increased. Overall, high bromide concentrations increased the calculated toxicity values in FBW and SSW after chlorination. Therefore, while currently challenging, technologies capable of removing bromide should be explored as part of a strategy towards controlling cumulative toxicity burden (i.e., hazard) while simultaneously lowering individual DBP concentrations (i.e., exposure) to manage DBP risks in drinking water. ? 2021 Elsevier Ltd. All rights reserved.

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