Formation Regularity And Precursor Of Disinfection By-products In Chlorination Of Simulated Swimming Pool Water

With the wide popularity of swimming,the water quality safety of swimming pool has been paid more and more attention.In order to kill the virus and microorganisms in the pool water,at present,chlorination disinfection is widely used in China to disinfect the swimming pool,however,in the disinfection process will produce chlorinated disinfection by-products(DBPs),which has a potential impact and threat on human health.Most domestic research on DBPs is based on drinking water and wastewater,although the health of swimming pools has been concerned by people,there are relatively few studies on DBPs in swimming pool water.The objective of present study is to used simulated swimming pool water as the test object to compare the potential of chlorinated DBPs in human body fluid analogues(BFA)and natural organic matter(NOM),which simulate the two main precursors of swimming pool water DBPs.At the same time,the chlorination test was carried out on each component of BFA to explore the potential of each precursor to form chlorinated DBPs,combined with the characteristics of swimming pool water,the formation trend of DBPs and the influence of various precursors on the formation of chlorinated DBPs in pool water were analyzed.On this basis to investigate the formation of disinfection by-products by simulated swimming pool water chlorination process under different conditions,evaluated factors included chlorination time,chlorine dosages,pH and reaction temperature,and analyze which conditions can effectively control the formation of DBPs.The results showed that during the chlorination,simulated swimming pool water could produce DBPs including dichloroacetic acid(DCAA),trichloroacetic acid(TCAA),chloroform(TCM),dichloroacetonitrile(DCAN),chloropicrin(TCNM)and 1,1,1-trichloroacetone(1,1,1-TCP).All three BFAs had high HAAs(DCAA and TCAA)formation potential,and the concentrations of HAAs(DCAA and TCAA)were significantly higher than that of THMs(TCM),BFA(J)had the highest formation amount of THMs and HAAs,the formation amount of DCAA produced by BFA(J)and BFA(B)was significantly higher than that of TCAA;BFAs components had different chlorination DBPs formation potential,the generation potential of HAAs and THMs in citric acid was much greater than that of the other components;The BFA had high generation potential for HAAs,while the NOM had high formation potential for THMs;The formation amount of THMs and HAAs increased and the increasing amount of HAAs was higher than THMs,when prolonged the chlorination time for BFA water samples and NOM water sample.The objective of present study is to investigate the formation of disinfection by-products by simulated swimming pool water chlorination process under different conditions.Evaluated factors included chlorination time,chlorine dosages,pH and reaction temperature.The results showed that the concentration of DCAA,TCAA and TCM increased constantly,the concentration of DCAN,TCNM and 1,1,1-TCP increased firstly and then decreased with the prolonged chlorination time.The concentration of DBPs increased significantly within 24 h of chlorination reaction,and became flat after 48 h;In response to increased dosage of chlorine,the concentration of DCAA,TCAA,TCM,TCNM and 1,1,1-TCP showed a tendency of increase,but the concentration of DC AN increased firstly and then decreased.The concentration of DBPs was lower when the chlorine dosage was controlled at 2 mg/L;With the pH increased from 6 to 8,the concentration of DCAA,TCAA,DCAN and 1,1,1-TCP initially increased and then decreased,and the concentration of TCM and TCNM increased gradually.When the pH was between 6 and 7,the formation of DBPs can be effectively controlled;With the increased of reaction temperature,the concentration of DCAA,TCAA,TCM and TCNM increased continuously,while the concentration of DCAN and 1,1,1-TCP decreased gradually.Overall,the chlorination conditions of the swimming pool water should be reasonably adjusted to effectively control the generation of DBPs and ensure the comfort level of the pool.In conclusion,the swimmer's behavior should be regulated,emphasizing the importance of taking a shower before swimming to minimizing the amount of metabolites that he body brings into the pool,the chlorination conditions of the swimming pool water should be reasonably adjusted to effectively control the generation of DBPs and ensure the comfort level of the pool.