| Contaminated by the urban sewage,industrial wastewater and agricultural irrigation in the upstream,the Yangtze River in Jiangyin section is regarded as micropolluted surface water.The micro-contaminated?organic compounds and ammonia?exceed the standard of surface water?III?and the current water treatment plant conventional water treatment process is difficult to protect the water quality.In current study,we used the downstream Yangtze River in Jiangyin section as the raw water and investigated the quality variations of raw water and effluent of sand filter in recent three years to definite the characteristics of raw water.Thereafter,we investigated the performance of ozone-activated carbon process and carried out experiment to optimize the operation parameters of ozone oxidation and granular activated carbon?GAC?filter.Then,the optimized operation parameters of O3-GAC process was obtained accordingly in terms of the raw water characteristics of Yangtze River in Jiangyin section and improved the contaminates removal performance of O3-GAC treatment,which significantly contributed to protect people's livelihood and promote social and economic green sustainable development.In present study,through the comparing of the water quality variations of Yangtze River in Jiangyin section and sand filter in recent three years,the raw water could be referred as micropolluted surface water.The concentration of ammonia nitrogen and organic matter(CODMn)in the raw water was relatively high and changed significantly with seasons.Furthermore,the quality of raw water is going worse and worse yearly.Additionally,the conventional drinking water treatment exhibits a poor removal for the micro-contaminated?organic compounds and ammonia?and couldn't guarantee quality of distribution water.Therefore,further advanced water treatment process should be employed to improve the water quality of effluent.The optimization of ozone oxidation process indicated that due to one-stage addition of ozone,the optimized dosage of ozone was 2.5 mg/L and the corresponding removal of UV254?CODMnn and ammonia were 63.90±3.59%?43.56±2.38%and71.83±4.65%,respectively.For two-stage addition of ozone,the optimized dosage of ozone was 2.0 mg/L and the corresponding removal of UV254?CODMnn and ammonia were 73.65±3.56%?57.65±2.61%and 86.14±3.83%,respectively.It was shown that two-stage addition of ozone was more beneficial to improve the removal of contaminates and oxidation efficiency of ozone,as well as reduce the dosage of ozone.Additionally,the dosage ratio of 1:1 was more helpful to adjust the distribution of ozone in the ozone reactor evenly,decrease the self-decomposition of ozone and improve the oxidation efficiency of ozone when two-stage addition of ozone was employed.The different material and shape of activated carbon exhibit a significant influence on the adsorption performance of activated carbon.In the experiment,in comparison with the iodine value and methylene blue value among four kinds of activated carbon?coal crushed carbon,coal column carbon,coconut crushed carbon and coconut column carbon?,it coulde be found that the iodine value and methylene blue value of column carbon is lower than that of crushed carbon,while iodine value and methylene blue value of coconut GAC is higher than coal GAC.Besides,the Yangtze River in Jiangyin section was used as raw water and the adsorption rate and adsorption capacity of the four GAC mentioned above were investigated in terms of CODMn.The results showed that the adsorption capacity and adsorption capacity of coconut crushed carbon were the highest,and the adsorption capacity and the average adsorption rate?30 min?were 7.23mg/g and 0.054 mg/?L·min?,respectively,which indicated that coconut crushed carbon was most suitable for the characteristicsof Yangtze River water in Jiangyin section.In this study,the optimization of operation parameters in O3-GAC process was carried out using Yangtze River water in Jiangyin section as raw water.The results indicated that the optimized running circles was 20 minutes.The optimal removal rate of UV254,CODMn and ammonia were 34.97±3.70%?55.66±3.78%?89.88±2.81%and the corresponding average removal rates were 2.37×10-4cm-1·min-1?6.38×10-22 mg/?L·min??2.67×10-22 mg/?L·min?.When the carbon filter backwash cycle is too long,it would lead to serious aging of the biofilm,while when the carbon filter backwash cycle is too short,it would lead to serious microbial loss and seriously affect the biodegradation of carbon filter.The optimal backwashing circle of carbon filter was5-10 days?the optimal cycle is 7 days?.The corresponding best removal rates of UV254,CODMn and ammonia were 38.76±3.73%,55.23±3.27%and 91.73±4.81%,respectively.The quality of effluentmeets therequirements of national drinking water health standards?GB5749-2006?in China,which control to protect people's livelihood and promote social and economic harmony and sustainable development.The depth of water purification plant monomer structure design,application of experimental data obtained from the study,water purification plant in the middle of the upgrade process pump station,the pre-ozone exposure ponds,the main ozone exposure ponds,activated carbon filters as well as ozone generator between the parameters were selected so that it can remove the city's water pollutants meet the national standard requirements.The economic and environmental impacts of the project are also analyzed.The overall efficiency and economic analysis of the process design are analyzed,economic and reasonable,providing technical reference for water treatment plant engineering.The test parameters applied to the actual engineering,the water plant processing capacity of 600,000 tons/day,the calculation results show that the estimated total investment of renovation project was 415,877,000 yuan,after the completion of renovation project,the new unit processing costs 0.288 yuan/ton.The implementation of the project is expected to provide safeguards for the local safe water supply and bring about enormous economic benefits and social benefits. |
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