| The purpose of this thesis was to provide data support for drinking water safety of zhejiang province and provide reference and basis for the relevant government decision-making, Through dynamic monitoring for varieties and contents of the typical source water chlorination disinfection by-products. To evaluation health risk assessment for different water source of drinking water on water quality and chlorinated disinfection by-products, applying the water environmental health risk assessment model. To determine the carcinogen risk and hazard index for human health from the harmful substances of chloridized disinfection by-products in drinking water and the main way to cause cancer risks and non cancer risks on the base of exposure ways and exposure dose analysis,MethodsAccording to water type of different regional, choose the finished water for the monitoring object, it used advanced treatment for five categories and worse five categories of water source from Tongxiang water group in Guoyuanqiao waterworks and the third waterworks of Haining Shikang water Co.,Ltd, or used conventional treatment for grade I and grade II of water source from Chun’an county water company and Deqing Zhonghuan water Co.,Ltd.Compare with the change of kind and content from chlorination disinfection by-products of source water of the different season,analyzed the influence factors of the formation of disinfection by-products chloride which included temperature, pH value, water quality,in order to understand species distribution and concentration of high and low from chlorination disinfection by-products of the finished water in different source water (the process of liquid chlorine disinfection).To evaluation health risk assessment for different water source of drinking water on water quality and chlorinated disinfection by-products.ResultsAccording to the Monitor, a phenomenon is source water pollution from organic solvent on Tongxiang and Haining.T he results show that bromide ion, ammonia nitrogen, total organic carbon concentration of source water affects chlorination disinfection by-products types and distribution. There was unobvious effect of pH and temperature on the effect of chlorination disinfection by-products.Water pollution situation:Haining finished water detected chlorobenzene, Tongxiang finished water detected methylene dichloride,1,2-dichloroethane, dimethoxymethane.The influence of THMs and HAAs from chlorine dosage, THMS increases with increasing residual chlorine concentration, it will not increase when reach a certain level. HAAs and other organisms oxidation reaction at the same time, explain HAAs precursor were higher than THMS precursor, its generation peak before THMS appear. The HAAs generation can achieve maximum when the ratio of TOC and residual chlorine between in1-2.The influence of water quality on DBPs:Experiments show that chlorinated vice product concentration decline and bromination vice product concentration increased when bromide ion concentration increased, chlorine and ammonia reaction formation chloramine (NH2Cl and NHCl2) and THMs decreases dramatically when ammonia existed more in water. THMs generation in steady state, the total amount of THMs than HAAs in normal circumstances.The content of THMs from finished water in Deqing and Chun’an were15.5μg/L-25.9μg/L and14.5μg/L-22.5μg/L respectively, but its content were9.30μg/L and6.3μg/L respectively on July7th,2012(the ammonia nitrogen of two finished water is less than0.1mg/L). THMs concentration greatly decreased and HAAs concentration increased significantly because the forest natural humus is flushed into the water in the wet season on July.THMS removal rate is70.5%when boil finished water0minute, THMS removal rate is96.4%when boil finished water1minute, the total content of DCAA、TCAA in boil finished water kept invariable basically.Conclusion1. By constrast,water resource in Tongxiang and Haining organic pollution to be seriously, although the two parts of the inferior water source with advanced treatment technology depth processing, the indicators of THMS and HAAs lower than the national standards, but higher than finished water indicators of Chun’an and Deqing. Its TACC carcinogenic risk value is2.32×10-5a-and2.37×10-5a-, results is very close to the standard of5.0×10-5a-, so the competent departments of the government of Haining and Tongxiang, should cause enough attention. Despite it had used advanced water treatment technology in Tongxiang and Haining, but there are certain limitations, environmental temperature and the concentration of pollutants had larger influence on the treatment effect of organic pollutants and ammonia nitrogen, however there are some unknown risks, So if you want to fundamentally solve the a series of problems from organic pollutants and ammonia nitrogen in water, the most effective way is to protect the source water.2. Due to the urban-rural water supply incorporate, water pipeline get long, increase for chlorine content, to make long distance pipeline residual chlorine not less than0.05mg/L, this will lead to increase residual chlorine of finished water, so it increased the concentration of the chlorination disinfection by-products. We suggest that the factory as far as possible to reduce the amount of chlorine. 3. In order to achieve the purpose of quick disinfection, invest a lot of bleaching powder, can generate large amount of disinfection by-products during the public emergency. This pollution should cause enough attention.4. The formation anomaly of THMs, HAAs can sensitive reflect the change of water quality in normal water treatment process conditions, Effects such as ammonia nitrogen content on them.5. The water is heated to boiling (100℃) after drinking is our country residents drinking water tradition, so the THMs cause health risks can be basically eliminated. HAAs carcinogenic risk far outweigh the THMs, and HAAs is non volatile organic compounds, so for the human cause risk of cancer of disinfection by-products chloride is mainly dichloroacetic acid, trichloroacetic acid. In addition, the ammonia nitrogen of finished water is on the high side seasonal in inferior water source due to the effect of environmental temperature for ammonia nitrogen treatment, they are certain dangerous to human health, This needs to be further studied.6. In recent years, Nitrosamines (include NDMA) it is a new type of chlorination disinfection by-products have been found in the finished water, in view of its stronger carcinogenicity, it has become the international research in the field of the frontier at present. The average concentration of dimethylnitrosamine (NDMA) is obviously higher than that of the free chlorine disinfection way, when water disinfection in the United States, Canada, Europe. Its and HOCl reaction formation chloramine (NH2C1, NHCl), when the water containing ammonia ion. Serious water pollution in this area, The ammonia nitrogen high value of source water is4.6mg/L, it often occurs, it is the factory water ammonia nitrogen content were higher than national drinking water hygiene standards, it high of3.6mg/L, because the cause of the risk is not clear, it will be further research. |
PDF Full Text Request