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Frontiers of Environmental Science & Engineering

ISSN 2095-2201

ISSN 2095-221X(Online)

CN 10-1013/X

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Front. Environ. Sci. Eng.    2020, Vol. 14 Issue (3) : 39    https://doi.org/10.1007/s11783-020-1214-4
RESEARCH ARTICLE
Comparative genotoxicity of water processed by three drinking water treatment plants with different water treatment procedures
Ting Zhang, Heze Liu, Yiyuan Zhang, Wenjun Sun(), Xiuwei Ao
School of Environment, Tsinghua University, Beijing 100084, China
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Abstract

• Genotoxicity of substances is unknown in the water after treatment processes.

• Genotoxicity decreased by activated carbon treatment but increased by chlorination.

• Halogenated hydrocarbons and aromatic compounds contribute to genotoxicity.

• Genotoxicity was assessed by umu test; acute and chronic toxicity by ECOSAR.

• Inconsistent results confirmed that genotoxicity cannot be assessed by ECOSAR.

Advanced water treatment is commonly used to remove micropollutants such as pesticides, endocrine disrupting chemicals, and disinfection byproducts in modern drinking water treatment plants. However, little attention has been paid to the changes in the genotoxicity of substances remaining in the water following the different water treatment processes. In this study, samples were collected from three drinking water treatment plants with different treatment processes. The treated water from each process was analyzed and compared for genotoxicity and the formation of organic compounds. The genotoxicity was evaluated by an umu test, and the acute and chronic toxicity was analyzed through Ecological Structure- Activity Relationship (ECOSAR). The results of the umu test indicated that biological activated carbon reduced the genotoxicity by 38%, 77%, and 46% in the three drinking water treatment plants, respectively, while chlorination increased the genotoxicity. Gas chromatograph-mass spectrometry analysis revealed that halogenated hydrocarbons and aromatic compounds were major contributors to genotoxicity. The results of ECOSAR were not consistent with those of the umu test. Therefore, we conclude that genotoxicity cannot be determined using ECOSAR .

Keywords Drinking water      Treatment process      Genotoxicity      Umu test      Ecological Structure-Activity Relationship     
Corresponding Author(s): Wenjun Sun   
Issue Date: 25 February 2020
 Cite this article:   
Ting Zhang,Heze Liu,Yiyuan Zhang, et al. Comparative genotoxicity of water processed by three drinking water treatment plants with different water treatment procedures[J]. Front. Environ. Sci. Eng., 2020, 14(3): 39.
 URL:  
https://academic.hep.com.cn/fese/EN/10.1007/s11783-020-1214-4
https://academic.hep.com.cn/fese/EN/Y2020/V14/I3/39
Fig.1  The water treatment schemes of three drinking water treatment plants (DWTPs) and sampling positions in: (a) DWTP A; (b) DWTP B; and (c) DWTP C.
DWTPs pH Turbidity (NTU) CODMn (mg/L) UV254 (cm?1)
DWTP A 7.4–7.8 0.4–0.02 1.5–0.01 0.02
DWTP B 7.3–7.7 20–0.05 3.0–0.03 0.19
DWTP C 7.1–7.3 27–0.05 5.5–0.02 0.17
Tab.1  Water quality parameters of raw water from three drinking water treatment plants (DWTPs)
Fig.2  Dose-effect curve of positive control 4-NQO.
Fig.3  Dose-effect curve of samples.
Fig.4  The variation of genotoxicity in each unit of three DWTPs: (a) DWTP A; (b) DWTP B; and (c) DWTP C. BAC, biological activated carbon. Error bar represents standard deviation (n = 3).
Treatment process Characteristic DWTP A DWTP B DWTP C
Conventional treatment Coagulant FeCl3 Al3SO4 Poly aluminum chloride (PAC)
Coagulant Dosage (mg/L) 80 34 /
Coagulation time (h) 1.1 5.4 0.5
The variation of genotoxicity after activated process 25%/32% −35% 24%
O3 Ozone dosage (mg/L) 2 1.3 2
Contact time (h) 0.1 0.42 0.25
The variation of genotoxicity after ozonation process 63% −2% 144%
BAC* Contact time (min) 9 54 14
The variation of genotoxicity after activated process −39% −77% −46%
Disinfect Disinfector Chlorine Chlorine Chlorine
Dosage (mg/L) 2 2.3 2.0
The variation of genotoxicity after activated process 218% 88% 46%
Tab.2  Comparison of the effects of water treatment processes from three DWTPs on the genotoxicity of substances in the effluents
Water DWTP A (spring) DWTP A (summer) DWTP B DWTP C
Raw water 5.4 ´ 107 5.8 ´ 107 3.4 ´ 106 4.0 ´ 106
Finished water 2.1 ´ 106 2.4 ´ 106 2.1 ´ 106 9.8 ´ 106
Tab.3  Carcinogenic risk of drinking water from three DWTPs (ng 4-NQO/L)
Fig.5  Variation in genotoxicity by Toxicity Estimation Software Tool (TEST) software in each unit of DWTP C. BAC, biological activated carbon. Error bar represents standard deviation (n = 3).
Fig.6  Variation in toxicity determined by ECOSAR software in each unit of DWTP C. The results can be classified as very toxic (<1 mg/L), toxic (1–10 mg/L), harmful (10–100 mg/L), and not harmful (>100 mg/L) based on the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) (UN, 2011). BAC, biological activated carbon.
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