The Study Of Micro-Polluted Water Purification Technology Design And Operation Under Low Temperature And Low Turbidity In A City

With the improvement of people's living standard,the requirement of drinking water has been transferred from water quantity to water quality.At present,the problem of organic pollution in drinking water is getting worse and worse.Some teratogenic and carcinogenic substances are easily produced in the traditional chlorination disinfection process,which affects the quality of city water.Therefore,it is imperative to develop new water purification technology.In December 2006,the National Drinking Water Hygiene Standard?GB5749-2006?was revised and issued by the Ministry of Health and the National Standardization Management Committee.In the new standard,the water quality index was increased from 35 items in GB5749-85 to 106 items,and 8 items were revised.The turbidity standard was increased from 3 NTU to 1 NTU.The revision of this standard not only guarantees the people's health interests,but also puts forward higher requirements for water supply enterprises.In view of the operation status of a waterworks in a city when dealing with low-temperature and low-turbidity raw water.Considering reducing the operation cost of the waterworks and ensuring the water quality to meet the standards,the process design and commissioning operation are optimized,most economical and most effective.The study aimed at the problems of micro-pollution of raw water,seasonal high incidence of algae,low temperature and low turbidity,odor and so on.According to the characteristics of low-temperature and low-turbidity water and starting from the analysis of water purification process,the study can guaranteed effluent water quality to meet the standard steadily through process optimization.In view of the limitations of ozone-activated carbon process on algae removal,permanganate pre-oxidation and high-density sedimentation tank process were used to make algae be killed and removed in the early stage,thus avoiding the restriction of algae on the O₃-BAC process.The microbial safety problems in the operation of water plants were studied.The microbial safety problems in ozone activated carbon process were solved by post-V sand filter,which could effectively avoid microbial leakage.At the same time,the combination process of high density sedimentation tank and ozone activated carbon process with V sand filter was selected by comparing the mainstream process schemes in strengthening coagulation,flocculation sedimentation,advanced treatment,filtration and disinfection and sludge treatment.Based on the conclusion of this study,a water purification plant with a recent 100000 m3 per day of low temperature,low turbidity and slightly polluted raw water in a city was planned and constructed.The operation effect of the water purification plant from June 2016 to March 2017 was investigated and analyzed.The results showed that the turbidity of raw water varies greatly,the other indicators except BOD5 meeted the surface water class II standard.During the operation period,the turbidity effect is obvious,the probability of effluent turbidity less than 1 NTU is 100%.The range of effluent turbidity of COD is 0.61-1.95 mg/L,and the removal rate is over 70%.The average ammonia nitrogen of effluent is 0.034 mg/L,and nitrite is 0.61-1.95 mg/L.The average nitrogen content was 0.004 mg/L,the average nitrate content was 3.6 mg/L.No bacteria,total coliforms and fecal coliforms were detected.All the indicators met the requirements of the Hygienic Standard for Drinking Water?GB5749-2006?.It showed that the process was safe and reliable,and it was a low temperature,low turbidity and slightly polluted water treatment technology that could be popularized.While investigating the treatment efficiency of the water purification plant,the economic analysis of the project was carried out,and the environmental impact of the water purification plant was evaluated with the corresponding environmental protection and energy saving measures,in order to achieve the best environmental,economic and social benefits.