Study On Disinfection By-products Produced By Reaction Of Chloramine And Anthracite

As a widely used pre-oxidant and disinfectant,chloramine has been studied in depth to produce halogenated disinfection by-products and nitrosamine-based disinfection by-products with natural organic matter in water.However,anthracite,as a commonly used filter material for drinking water treatment,has similar components to natural macromolecular organics such as humic acid.Humic acid and chloramine-containing water will react to produce disinfection by-products(DBPs),but whether anthracite coal also has the risk of generating DBPs has been ignored by people.Therefore,the purpose of this study is to investigate the regularity of halogenated disinfection by-products and nitrosamine disinfection by-products produced by chloramine and anthracite filter materials,and to reveal the risks of anthracite as filter materials.Therefore,the purpose of this study is to investigate the regularity of halogenated disinfection by-products and nitrosamine disinfection by-products produced by chloramine and anthracite filter materials,and to reveal the risks of anthracite as filter materials.This study explored the effects of variables such as p H,chloramine concentration,anthracite quality,and reaction time on the formation of halogenated DBPs and nitrosamine DBPs from chloramine and anthracite.The reaction of anthracite leaching solution with chloramines to generate DBPs and the formation of DBPs from chloramines and anthracite filter media in the actual water body also were investigated.Finally,the dynamic filtration experiment and backwash experiment were carried out to study the rule of DBPs generated by chloramine and anthracite in the actual water treatment process.The study found that p H has a similar significant effect on the production of halogenated DBPs and nitrosamine DBPs from chloramine and anthracite,and the generation of both DBPs is significantly higher under alkaline conditions;The increase of chloramine concentration will promote the generation of halogenated DBPs,while the generation of most nitrosamines DBPs will increase first and then decrease.When the concentration of chloramine is 10 mg/L,the generation reaches the maximum,and when the concentration of chloramine reaches 15 mg/L,the generation tends to be stable.Due to the smaller adsorption area of low-quality anthracite,the generation of two kinds of DBPs is higher when the quality of anthracite is lower.Studying the effect of reaction time on the amount of nitrosamines DBPs found that a large amount of nitrosamines DBPs were generated within 1 hour of the reaction,and the amount of production did not increase significantly within 8 hours,and after 5 days of reaction,the production ofvarious nitrosamine DBPs increased and tended to be stable;The reaction of anthracite leach solution with chloramine to produce nitrosamine DBPs was investigated.It was found that the leach solution will also react with chloramine to produce a large number of nitrosamine DBPs.And because there is no adsorption of anthracite in the leaching solution,the concentration of NDMA generated by the reaction of the leaching solution with chloramine is higher than the concentration of NDMA generated by the direct reaction of anthracite with chloramine.According to the study of DBPs generated by chloramine and anthracite in the actual water background,it is found that the amount of DBPs generated in the actual water background is significantly increased,so the risk of anthracite as a filter material to generate disinfection by-products in the actual water treatment process is greater than that in the experimental study.Finally,simulating the dynamic filtration and backwashing process in the actual water treatment,and detecting the generation of halogenated DBPs and nitrosamine DBPs,it was found that most of the generation of halogenated DBPs and nitrosamine DBPs decreased first and then increased with the increase of filtration time in the dynamic filtration experiment,and the generation was the smallest on the 7th day of reaction,and reached a stable 13 days after reaction.However,after backwashing,the amount of halogenated DBPs did not have obvious change,but the amount of nitrosamine DBPs decreased significantly,with a maximum reduction of 59.7%.