摘要
Chlorination,the most widely used disinfection process for water treatment,is unfortunately always accompanied with the formation of hazardous disinfection byproducts(DBPs).Various organic matter species,like natural organic matter(NOM)and amino acids,can serve as precursors of DBPs during chlorination but it is not clear what types of organic matter have higher potential risks.Although regulation of DBPs such as trihalomethanes has received much attention,further investigation of the DBPs driving toxicity is required.This study aimed to identify the important precursors of chlorination by measuring DBP formation from NOM and amino acids,and to determine the main DBPs driving toxicity using a theoretical toxicity evaluation of contributions to the cytotoxicity index(CTI)and genotoxicity index(GTI).The results showed that NOM mainly formed carbonaceous DBPs(CDBPs),such as trichloromethane,while amino acids mainly formed nitrogenous DBPs(N-DBPs),such as dichloroacetonitrile(DCAN).Among the DBPs,DCAN had the largest contribution to the toxicity index and might be the main driver of toxicity.Among the precursors,aspartic acid and asparagine gave the highest DCAN concentration(200 g/L)and the highest CTI and GTI.Therefore,aspartic acid and asparagine are important precursors for toxicity and their concentrations should be reduced as much as possible before chlorination to minimize the formation of DBPs.During chlorination of NOM,tryptophan,and asparagine solutions with different chlorine doses and reaction times,changes in the CTI and GTI were consistent with changes in the DCAN concentration.
基金
the National Natural Science Foundation of China(Grant No.51678332 and 51738005)
the Shenzhen Science,Technology and Innovation Commission(Grant No.JCYJ20170818091859147)
the special support program for high-level personnel recruitment in Guangdong Province(Grant No.2016TQ03Z384)
the Development and Reform Commission of Shenzhen Municipality.
