Study On The Detection And Influencing Factors Of Haloacetic Acid Disinfection By Products In Drinking Water Of H City

PurposeChlorination disinfection was the most common and effective disinfection method used in most small and medium-sized water plants in China.It can effectively kill pathogenic microorganisms in water and prevent the occurrence and spread of waterborne infectious diseases.However,in the process of disinfection,chlorine agent can react with organic substances in water to produce disinfection by-products harmful to human healthy.In this study,the disinfection by-products of haloacetic acid,which have great carcinogenic risk to human beings,were selected as the research object.By establishing the detection and analysis method of HAAs in drinking water,the haloacetic acid in the treated water and the terminal tap water in H city was regularly monitored,so as to understand the concentration and distribution of haloacetic acid in drinking water in H city.Combined with the results of routine water quality investigation,the influencing factors of haloacetic acid formation in treated water and terminal tap water were discussed.MethodIn this study,from March to November,2022,the treated water and terminal tap water were taken as the research objects in different districts in H city.and the haloacetic acid in the treated water and the terminal tap water were detected and analyzed by using the established high performance liquid chromatography-mass spectrometry series method.Mann-Whitney U test or Kruskal-Wallis H test were used to compare the concentration levels of haloacetic acid compounds in treated water and terminal tap water in different seasons and different sampling points.Spearman correlation test and multiple linear regression analysis were used to explore the influence of different water quality indexes in treated water and terminal tap water on the formation of haloacetic acid.Results1.In this study,by optimizing the conditions of chromatography and mass spectrometry,a high performance liquid chromatography-mass spectrometry（HPLC-MS）tandem method was established for the rapid and sensitive detection of 9haloacetic acids in drinking water.The Waters ACQUITY UPLC HSS T3 column was selected as chromatographic column,and 0.05%acetic acid water and methanol were used as mobile phase.The results indicated that the retention time of nine haloacetic acids was between 2.51 and 4.12 min.Nine haloacetic acids had good linearity in their respective determination ranges,and the standard correlation coefficients were all greater than 0.999.The detection limit and quantitative limit were 0.058～0.53μg·L^-1and 0.17～1.59μg·L^-1,respectively.The recovery rate of the sample was within 93.40%～117.52%,with the precision down to 10%.2.A total of 96 samples of raw water and treated water were collected in this survey,and five kinds of HAAs were mainly detected in the water,namely DCAA,TCAA,BCAA,MBAA and BDCAA,among which DCAA and TCAA were the main compounds.The total HAAs concentration in the treated water was 14.92～21.58μg·L^-1in different seasons,and the total HAAs concentration in winter was less than that in summer and autumn（P<0.05）.The concentrations of total HAAs,DCAA and BCAA in the treated water were higher than those in the raw water（all P<0.05）,and the total HAAs concentrations in the raw water and the treated water were 5.729μg·L^-1and 19.607μg·L^-1.The correlation linear regression analysis between the water quality index and the concentration of HAAs showed that the formation of HAAs was positively correlated with the concentration of COD_Mn（r=0.560,P<0.001）and negatively correlated with the concentration of ammonia nitrogen（r=-0.599,P<0.001）.3.In different districts of H city,50 monitoring points for the terminal tap water were set up respectively,and 300 water samples were collected.The concentration of HAAs in the terminal tap water of different districts ranged from 5.68μg·L^-1to 15.38μg·L^-1,and the total concentration of HAAs in the terminal tap water in LH area and XY area was higher than that in ML area（P<0.05）.The results indicated that the concentration of HAAs in the terminal tap water was higher in wet season than in dry season（P<0.05）.The linear regression analysis of the water quality index at the terminal tap water and the concentration of HAAs indicate that the formation of HAAs was significantly positively correlated with residual chlorine and iron ions（r=0.707,P<0.05;r=-0.530,P<0.05）,which was negatively correlated with p H value（r=-0.309,P<0.05）.ConclusionsBy establishing a high performance liquid chromatography-tandem mass spectrometry tandem method that can be simply,quickly and sensitively detected nine haloacetate in drinking water.Different concentrations of HAAs were detected in the treated water and terminal tap water among which DCAA and TCAA were the main ones.Different seasons can affect the concentration level of HAAs in the treated water and the terminal tap water.Different urban locations can affect the concentration change of HAAs in the terminal tap water.Different water quality indexes can affect the formation of HAAs in different degrees,among which the main factors affecting the formation of HAAs in the treated water are COD_Mnand ammonia nitrogen,and the main factors affecting the formation of HAAs in the terminal tap water were residual chlorine,iron ions and p H value.