| With the rapid development of Chinese city and the improvement of economic situation of people,which stimulate the requirements for the environment protection.However,the ways of water pollution are becoming more and more complicated.Non-point source pollution is the main reason for the formation of black-odor river water bodies in China.Research shows that the issue of black-odor river caused by non-point source pollution should be attentioned.By the end of 2016,the ratio of black-odor river in China is reported to reach the level of as high as 75%.Eliminating black-odor river water bodies become one of Chinese important national issue.It is great significance to find a cheap and effective method to control black-odor river water bodies.The external circulation technology shows the advantages of convenience and adaptability to local conditions for disposing the black-odor river water bodies produced by runoff pollution or domestic sewage.Supported by the National Science and Technology Major Project for the Control and Treatment of Water Pollution from the Ministry of Science and Technology of China under Grant No(2011ZX07301-003),pilot-scale study of external circulation treatment technology was conducted.Based on the feasibility analysis of river data analysis and pilot test design in Suzhou City,the river water in the Guandu garden of Suzhou City was selected as the raw water for the pilot test study of the water treatment of the black-odor river,and the technology was adopted with the nitrogen and phosphorus removal technology.Cycling treatment technology is used to dispose the water bodies in the inland river of Guandu garden with mild black smelly water.The construction of related structures is carried out.After the completion,long time monitor is conducted to investigate the effect.The device consists of two units to achieve a good treatment effects.The submersible pump is used to bring the Guandu garden river water into the inner of the external circulation processing equipment.After filtration,aeration,and nitrogen and phosphorus removal by the filler,finally returns to the river course.Results showed:(1)According to the data analysis and research on the water bodies of various rivers in Suzhou City,the monitoring data of 28 monitoring sections in 2016 were analyzed by using single factor and cluster analysis methods.The results showed that the black smelly of rivers in Suzhou City were greatly improved.However,there are some rivers still belong to the mild black-odor water that need appropriate treatment measures to renovate them.(2)From September 2016 to March 2017,the black-odor water bodies in the river of Suzhou City were disposed with external circulation treatment facilities.The results showed that the effluent concentration of COD,TN,NH3-N,TP decreased to 21.65 mg/L,4.75 mg/L,1.35 mg/L,0.23 mg/L,respectively,all of the other water quality indexes reached the class IV standard of“Surface Water Quality Standards"(GB 3838—2002)except TN.The treatment facilities showed strong anti-shock load and can be recovered in a relatively short period of time.(3)The analysis of relevant data showed that the removal of nitrogen in the inland river water of Guandu garden that entered the external circulation processing equipment mainly depends on the nitrification and denitrification of microorganisms inside the filler,and the removal of phosphorus was mainly depended on the releasing of phosphorus in the denitrification and dephosphorization tank.After then,the phosphorus was absorbed in the aeration tank,finally the function of removing phosphorus was achieved.(4)The change of hydraulic retention time had an influence on the treatment effect of the external circulation treatment equipment.The hydraulic retention time of the equipment was maintained between 0.81?1.78h,which could effectively remove the main pollutants in mild black-odor water.Hydraulic residence time could be adjusted according to the treatment standards to achieve the required treatment standards.The reduction of hydraulic retention time will have a certain effect,but the external circulation equipment had a strong Anti-shock load capacity,can reduce the influent water quality pollution in the case of low temperature,high load,and the final effluent can reach surface water class IV water standards.(5)Comparing the comprehensive experimental results,material costs and other aspects,the external circulation treatment technology showed a good treatment effect on the black-odor river water bodies caused by non-point source pollution,is friendly to the surrounding environment.It also has high availability,and broad application prospects. |
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