Study On Safety Disinfection For Building Domestic Hot Water

There are different levels of water pollution in the hot water system of the hot water, which caused the quality of water safety problems.In these problems, the safety of the biological problem may cause a direct threat to the human body. Therefore, we need to find a safe, economic and efficient disinfection technology to protect the security of hot water in our daily life and provide theoretical support.In this paper, the research object to the construction of hot water. We done a city water research and analyzed the laws of domestic hot water pollution and its influencing factors. We also examined the laws of chlorine and chlorine dioxide attenuation and the factor of disinfection byproducts generation. Meanwhile, we examined the safety of chemical disinfectants of domestic hot water. We studied the sodium hypochlorite, chlorine dioxide and silver ions in hot water systems for inactivation of microorganisms in hot water, and investigated the disinfection`s capability.The investigation of domestic hot water pollution showed that the residence time of domestic hot water is too long to make some of the indicators can not reach the "drinking water health standards"(GB5749-2006) requirements. The living water through the water heating system,becomes domestic hot water, which lead to the increases of chloroform, conductivity, turbidity, and bacteria, meanwhile it cause the reduce of chlorine and other issues, and then, the security of domestic hot water is under the risk.Attenuation of disinfectant and the impact of by-products study shows that elevated CODMn content can accelerated chlorine and chlorine dioxide decay rate, and it can promote the generation of chloroform and chlorite. It was no significantly effect of pH on chlorine dioxide and chlorine decay on, but the increase of pH will promote the production of chloroform and chlorite. To ensure biosafety premise of hot water, reducing the concentration of chlorine and chlorine dioxide, CODMn concentration and pH, can effectively reduce the generation amount of chloroform and chlorite.The result of Chlorine and chlorine dioxide disinfection indicate that chlorine and chlorine dioxide play a significant role in killing microorganisms in hot water. when 40?, the dosing of chlorine ?0.5mg/L can cause excessive chloroform. Adding <0.5mg/L of chlorine in hot water has likely to result in the case of non-compliance chlorine, and the safety of biosafety may under risks. So, the chlorine disinfection in the domestic hot water is not ideal. Compared with chlorine, chlorine dioxide has less investment and less time and with strong advantages. Chlorine dioxide concentration in the 0.3mg/L or less in the test without causing excessive chlorite phenomenon. Compared with chlorine, chlorine dioxide is more suitable for disinfecting water systems.The results of silver ion disinfection show that 0.051mg/L of silver ion in hot water circulation system which had significant effect on bacteria, heterotrophic bacteria and escherichia coli, and the water quality is qualified after 80 min disinfection. With the increase of temperature and concentration of silver ions, the rate of silver ions on microbial inactivation showed significant improvement trend. In the range of 0~240h disinfection time,although the concentration of silver ions by 0.10 mg/L reduced to 0.04mg/L,but the total number of bacteria always remain below the 150cfu/mL, escherichia coli has been below the 5cfu/100 m L, we can perorate that silver ion has excellent persistent disinfection ability.