ENVIRONMENTAL POLLUTION
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2024
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IF 7.6
Xuanxuan Xian,Chen Luo,Gang Lian,Xin Yu,Liang Zhu
Pre-chlorination is usually applied to facilitate coagulation process when treating cyanobacteria-laden source waters. However, the responses of cyanobacteria after chlorination were varied in different growth phases, hence how these differences affect the coagulation is not clear. In this study, Microcystis aeruginosa ( M. aeruginosa ) in late lag and exponential phases were selected for comparing the remove effect of cyanobacterial coagulation after varied doses (0, 0.5, 1.0 and 2.0 mg/L) of pre-chlorination. Results showed that the M. aeruginosa in late lag phase held higher removal efficiencies (48–86%) than those in exponential phase (1–60%). Lower pH and buoyancy, higher Zeta potential and hydrophobicity were beneficial to its coagulation. The application of 0.5–2.0 mg/L pre-chlorination in late lag phase did not promote its coagulation, mainly due to the impediment by released hydrophilic humus. In contrast, the remove efficiency increased about 40% with the addition of 2.0 mg/L chlorine and 15 mg/L polyaluminum chloride (PACl) in exponential phase. The increased macromolecular organic matters, Zeta potential and decreased buoyancy made for this promotion. In addition, the removal of extracellular organic matters, aromatics and microcystin was not that productive after coagulation in exponential phase, but both of chlorination and coagulation could reduce microcystin in late lag phase. The findings suggest that optimizing the application methods of pre-chlorine and coagulant according to the growth phases is necessary for cyanobacterial control.
研究领域:
环境科学
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水处理工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
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2022
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IF 10.753
Ruya Chen,Xin Huang,Guiwei Li,Ying Yu,Baoyou Shi
Granular activated carbon (GAC) adsorption is one of the best available technologies for removing perfluoroalkyl substances (PFASs) from drinking water . However, GAC processes in full-scale drinking water treatment plants frequently encounter unstable, even negative removal efficiency on PFASs due to the lack of understanding between the GAC characteristics and the PFASs polluted water quality conditions. In this study, the scenarios of raw water pre-chlorination and emergency contamination by multiple PFASs were simulated to evaluate the PFASs control performance by in-service GAC with different properties and ages. The results showed that the adsorption of a relatively longer-chain PFAS by the in-service GAC can be achieved by replacing the pre-adsorbed natural organic matter (NOM). The increased lower molecular weight NOM after pre-chlorination could compete with PFASs for adsorption sites and exacerbate the pore blockage, thus significantly weakening the PFASs removal ability of in-service GAC. When multiple PFASs entered the water by emergency contamination, the PFASs with stronger hydrophobicity could replace the PFASs with less hydrophobicity that had previously been adsorbed on GAC. GAC with a higher proportion of micropores had a lower risk of PFASs leakage facing the water quality changes.
研究领域:
环境科学
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水处理工程
✓ 已验证
DOI
高影响因子
WATER RESEARCH
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2019
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IF 7.913
Tian-Yang Zhang,Bin Xu,Shijie Yao,Yaru Hu,Kuangfei Lin,Hui Ye,Changzheng Cui
Pre-chlorination and UV disinfection are two common processes in drinking water treatment plants. Sulfamethoxazole (SMX), an antibiotic widely detected in source water, was selected as a precursor to study the conversion of chlorine/nitrogen species and DBP formation in pre-chlorination/post-UV process. The combined chlorine (mainly organic chloramines) produced in pre-chlorination of SMX can self-degrade and release free chlorine back again as pre-chlorination time goes on. With free chlorine dose increasing, the self-degradation rate of combined chlorine increased obviously. But the combined chlorine stopped self-degrading and remained stable around 1 mg-Cl 2 /L after adding 0.30 mM chlorine for 30 min. Post-UV treatment after pre-chlorination can enhance the degradation and achieve a complete removal of combined chlorine (including organic chloramines). Deamination occurred during pre-chlorination/post-UV process and deamination amount (-NH 2 ) per SMX concentration was 0.19 M/M. Radicals in this process had no obvious influence on chlorine/nitrogen species conversion. Direct chlorination of SMX had the lowest DBP formation potentials while the application of pre-chlorination and UV enhanced them. Compared with UV treatment only, dichloroacetonitrile formation potential of SMX reduced by 1.58 × 10 −3 mol/mol-SMX (17.37 μg/l) after pre-chlorination/post-UV treatment. During pre-chlorination/post-UV/final-chlorination treatment of SMX, Br − and natural organic matter can enhance DBP formation and toxicity-weighted values. Acid conditions showed a very high DBP risk, while alkaline conditions could cut this risk obviously, especially for the toxicity-weighted values of these DBPs.
研究领域:
环境科学
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水处理工程
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公共卫生
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
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2022
·
IF 10.753
Mengze Geng,Xin Huang,Baoyou Shi,Jianwei Yu,Chunmiao Wang,Yuning Du,Yili Wang
Swampy/septic odor caused by thioethers has become the main taste and odor (T&O) problem in drinking water of China. Improving its removal performance by commonly traditional water treatment process is significant. In our study, we have found that pre-oxidation could modify the background dissolved organic matter (DOM) properties and thus improve the coagulation performance of thioethers , increasing the coagulation removal rates by 1.5–3 times. Particularly, after pre-ozonation only protein-like substances remained, and thioethers removal was 1.5 times higher than that after pre-chlorination (only coagulation not including oxidation). Compared with humic acid (HA), the thioethers compounds removal efficiencies under bovine serum albumin (BSA) as background DOM was increased by 0.3–3 times. Through Freundlich model analysis, the binding strength of BSA (K F = 20.712, at 298 K) to dimethyl disulfide (DMDS) was enhanced by 60 % compared to HA (K F = 12.778, at 298 K). According to thermodynamic parameters, the binding effect between HA/BSA and thioethers compounds was mainly van der Waals forces and hydrogen bond . BSA with more amino structure and oxygen groups was more easily to adsorb DMDS through hydrogen bond and thus achieved better coagulation performance. Therefore, pre-ozonation combined with coagulation was suggested to be more suitable for thioethers compounds control.
研究领域:
环境科学
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水处理
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化学工程
✓ 已验证
DOI
PubMed
高影响因子
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