期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 692, 期 -, 页码 117-126出版社
ELSEVIER
DOI: 10.1016/j.scitotenv.2019.07.2017
关键词
Disinfection byproducts; Dechlorination; Developmental toxicity; Primary sewage effluent
资金
- Environment and Conservation Fund
- Woo Wheelock Green Fund [ECWW15EG07]
- Research Grants Council, University Grants Committee of Hong Kong, Theme-based Research Scheme [T21-711/16R]
- Collaborative Research Fund [C7044-14G]
- National Natural Science Foundation of China [51508335]
- Natural Science Foundation of Guangdong Province [2016A030310061]
- Shenzhen Science and Technology Project [JCYJ20170818091859147]
Chlorine-disinfected sewage effluents are typically dechlorinated by using NaHSO3, Na2SO3, or Na2S2O3, as chlorine residual could be harmful to aquatic organisms upon discharge of sewage effluents into receiving marine water. In this study, we systematically investigated the effects of dechlorination-related factors on the developmental toxicity of a chlorinated saline primary sewage effluent, via direct exposure of the embryos of a marine polychaete to the effluent. The results showed that dechlorination ratio (i.e., the ratio of the dosed amount to the requisite stoichiometric amount of a dechlorination agent) and mixing condition were critical factors affecting the toxicity of the effluent. The toxicity of the effluent under insufficient dechlorination conditions was mainly caused by residual chlorine. especially monochloramine. Although the three dechlorination agents generally performed similarly, dechlorination with Na2S2O3 required a more vigorous mixing condition than that with NaHSO3 or Na2SO3, as the relatively high density of Na2S2O3 might affect the mixing efficiency. Under insufficient mixing conditions, a prolonged dechlorination time was beneficial to achieving complete dechlorination and thus lowered the toxicity of the effluent. Moreover, because disinfection byproducts (DBPs) may have chronic effects on aquatic organisms, the developmental toxicity of the DBP mixtures in the chlorinated effluent in different dechlorination scenarios was also evaluated. The results indicated that increasing the dechlorination ratio reduced the developmental toxicity of the DBP mixture in the chlorinated saline sewage effluent, which might be ascribed to the decrease of the levels of overall brominated and iodinated DBPs: the dechlorination agent (NaHSO3 or Na2S2O3) might act as a nucleophile in the nucleophilic substitution and cause the substitution of bromine or iodine atoms in brominated and iodinated DBPs. The results from this study might aid in the design and operation of dechlorination facilities in sewage treatment plants. (C) 2019 Elsevier B.V. All rights reserved.
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