| Trihalomethanes and haloacetic acids are the most common and most concerned disinfection by-products.Based on the inherent characteristics of the quality of Xijiang water in drinking water sources in Zhongshan City,this paper studies the formation characteristics and influencing factors of disinfection by-products,and conducts risk assessment of disinfection by-products.Finally,a pilot test is conducted.It provides data foundation and scientific guidance for the disinfection of alternative liquid chlorine in drinking water sodium hypochlorite in Zhongshan City,in order to improve the water quality of tap water in Zhongshan City,reduce the production of disinfection by-products,especially the salt water production period,and ensure people's drinking water safety.The generational cancer risk R of the water source disinfection by-products was 2.40×10-6 ~3.85×10-6,and the cancer risk was greater than the risk threshold 1.0×10-6 recommended by the US Environmental Protection Agency.Big hidden dangers.Among them,the lifetime cancer risk of haloacetic acid is 91.56% ~ 93.93% of the total lifetime cancer risk,which is an important part of the lifetime cancer risk.The lifetime carcinogenic risk and the non-carcinogenicity of each source water exposed by the skin route are 3.737×10-8 ~6.9×10-8,7.99×10-9 ~1.23×10-8,respectively,which are far lower than the recommended by USEPA.The risk threshold is 1.0×10-6.Among them,the lifetime non-carcinogenic risk of dichloroacetic acid is an important part of the lifetime non-carcinogenic risk.Through the laboratory test,the formation characteristics and influencing factors of the generation potential of disinfection by-products of drinking water sources in Zhongshan City were studied.The study found that the initial p H value of the water sample,the amount of available chlorine,the reaction time,the ammonia nitrogen concentration,and the bromide ion concentration have a significant effect on the amount of disinfection by-products.The initial p H value of the water sample is in the range of 5~9 and the effective chlorine dosage is 1~10mg/L.The amount of disinfection by-products increases with the increase of the effective chlorine dosage.Total trihalomethane and total haloacetic acid And the total disinfection by-products increased significantly.When the effective chlorine dosage is ?5mg/L,the total disinfection by-product is linear with the initial p H value of the water sample,and when the effective chlorine dosage is ?5mg/L,the percentage of trihalomethane increases with the p H value.It rises and is a major component of disinfection by-products.The amount of trihalomethanes increases with the increase of p H value.The haloacetic acid decreases with the increase of p H,and the total amount of disinfection by-products increases with the increase of p H value.Under the condition of the initial p H value of the water sample,the various disinfection by-products increased significantly with the increase of reaction time(3h~24h).With the increase of ammonia nitrogen concentration,the production of various trihalomethanes decreased,the total trihalomethanes and total disinfection by-products also decreased,and the amount of bromochloroacetic acid and dibromoacetic acid produced did not change much.The addition of ammonia nitrogen can effectively reduce the amount of disinfection by-products.At the initial p H=7.0 of the water sample,chloroform and monobromodichloromethane decreased with increasing bromide ion concentration,dibromochloromethane first increased and then decreased,bromoform,trihalomethane and total Disinfection by-products increase rapidly as the concentration of bromide ions increases.At different ammonium nitrogen concentration bromide ion concentrations,the initial p H of the water sample = 5.0 relative to the initial p H = 7.0,the disinfection by-products decreased significantly.It is recommended that the initial p H value of the water sample be adjusted to 5~7 before the disinfection,the effective chlorine dosage is controlled below 5mg/L,the disinfection time should be shortened as much as possible,and the appropriate amount of ammonia nitrogen should be added,and the bromide ion content in the water can be reduced.Through the pilot study,the removal effect of ammonia nitrogen,CODMn,UV254 and TOC in the effluent was investigated.It was determined that the optimal dosage of ozone was 1.5 mg/L and the adsorption time of activated carbon was 10.18 min.The dosage of ozone increased from 0.50 mg/L to 2.0 mg/L.The total removal rate of ammonia nitrogen from ozone-activated carbon treatment increased from 34.41% to 48.28%,but the removal rate after ozone dosage ?1.0 mg/L.The best is not obvious.When the dosage of ozone was 1.5mg/L,the ozone-activated carbon treatment process increased the removal rate of CODMn by 21.21%,the activated carbon effluent UV254 was 0.007cm-1,and the TOC was 1.42mg/L.The removal rate reached 54.49%,and the removal rate increased by 16.35% compared to the conventional process effluent.Under the optimal deep treatment process conditions,the pilot plant has a good removal effect on conventional water quality indicators.Turbidity,ammonia nitrogen,CODMn,UV254,TOC,etc.are lower than the sanitary standards for drinking water.In addition,the ozone-activated carbon advanced treatment process has a good removal effect on the disinfection by-product precursor.After sand filtration,THMFP was 35.66 ug/L,activated carbon effluent was 25.69 ug/L,the cumulative removal rate increased from 64.25% to 73.24%,and the removal rate increased by 8.99%.The effect was not obvious.The total HAAFP of raw water is 34.15 ug/L,the final effluent is 10.72 ug/L,the overall removal rate is 68.60%,which is 22.35% compared with 46.25% of the filtrated effluent,and the cumulative removal rate of total DBPFP is 72.07%.The effluent increased by 13.51%. |
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