Study On The Process Design Of The Second Stage Project Of A Sewage Treatment Plant In South China

A sewage treatment plant in the south is located next to the exit of the central flood discharge channel and is mainly responsible for sewage treatment and collection in the urban area.The main treatment process of the first phase of the sewage treatment plant is the C ASS process,and the sewage is discharged into the Xijiang River after being treated.In this project,the treatment process of the second phase of a sewage treatment plant is taken as the research object.In the first phase,the suspended substance,phosphorus,nitrogen in the tail water cannot stably reach the local standard of Guangdong Province,the“Water Pollutant Emission Limit”(DB44/26—2001)at the time of first-grade standards and C lass A requirements of the first-grade standard of the Urban Wastewater Treatment Plant Pollutant Emission Standard(GB18918—2002),and the urgent need to expand the scale of the sewage treatment,the water quality of the first phase of the sewage treatment plant was analyzed.Problems,research and design of the second-phase project design scale,design influent water quality,design water quality indicators,and nitrogen and phosphorus removal treatment process,coagulation sedimentation process,filtration process,disinfection process,sludge treatment process,deodorization process,etc.Conduct technical and economic analysis and propose a reasonable process upgrade and reconstruction program.The main results are as follows:1.According to the special drainage plan,the amount of wastewater in the sewage treatment plant will reach 50,000 m~3/d in the near future.Therefore,the designed wastewater volume of the second phase of the sewage treatment plant will be set to30,000 m~3/d,that is,the scale of expansion.It has a capacity of 30,000 m~3/d(the first phase of the project to treat the wastewater of 20,000 m~3/d).After the expansion,the total scale will reach 5,000 m~3/d.2.Through comprehensive comparison and selection of multiple processes,the utilization and matching of the original facilit ies and equipme nt will be considered.The selection of high-density clarifiers,filter cloth filters,ultraviolet filters,belt-type integrated filter presses,and biological deodorization are the preferred methods.Coagulation and sedimentation process,filtration process,disinfection process,sludge treatment process and deodorization process.3.Fully consider the problem of staged convergence,make effective use of existing facilit ies and equipment,minimize duplication of investment,and comprehensively refer to the characteristics of the process,the effects of treatment,the operation and management,the impact on the operation of the existing sewage treatment plant in the construction process,the total project investment,and operating costs O ther factors,such as the C ASS process and the improved C ASS process,were compared and selected.Finally,the improved CASS process was selected as the second stage nitrogen and phosphorus removal treatment process.The main flow of the second stage sewage treatment process is determined as:grit chamber+modified C ASS front section(new)+modified C ASS pool sequence lot(current CASS pool reconstruction)+high-density clear bubble+filter cloth filter+disinfection tank.4.After the second phase of the sewage treatment plant was upgraded and put into operation,the quality of the effluent water is stable to meet the C lass I standard in the second period of the local standard“Water Pollutant Emission Limit”(DB44/26—2001)and C lass A of the C lass I Standard of“the Urban Pollutant Discharge Standard for Pollutants”(GB18918—2002),and good sewage treatment.