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Building sewage treatment plants is to protect the water environment from pollution is one of the most important measures.In order to better protect the water environment, urban sewage treatment plant effluent discharge standards are more stringent,especially with the growing eutrophication,nitrogen and phosphorus removal has become a city sewage treatment plant process selection one of the main basis. Since the statepromulgated the"municipal wastewater treatment plant emission standards"(GB18918-2002),for a betterdesign of the requirements,so select a citysewage treatment processis morecomplex.The main subject for heavy chemical plant employees to carry out research,including water to detennine water quality analysis,treatment process selection and optimization of design parameters,the final completion of engineering design.Heavy chemical Fengzhen City Park sewage treatment plant influent,including sewage and Fluorine-based chemical and metallurgical industry of industrial wastewater,design flow is20,000m3/d.According to the EPA Fengzhen City displacement surveys and water quality monitoring data,design of the main indicators of water quality to determine the BOD5,COD,SS,NH3-N,TN,TPwere:200mg/L,500mg/L,300mg/L,20mg/L,25mg/L,2mg/L.Determined in accordance with the water function zoning Heihe perfonn"municipal wastewater treatment plant emission standards"(GB18918-2002)a Class B standard,the final treated water discharged into the Black River.Through technical and economic comparison,the final pre-treatment process is Mechanical pretreatment-acidification-A2/Obiological treatment-secondary settling tank-contact disinfection combined process;sludge using mechanical concentration,press dewatering process.As the actual situation of low winter temperature,optimal adjustment of the traditional design parameters.Finally,detailed analysis of the sewage treatment plant construction costs and processing costs.To A2/O process in detail as the core design process, summarize a set of design parameters with the reference value. The main structures of which the design of water acidification tank:20,000m3/d,effective volume:5000m3, residence time:6h, Size:50.0x20.Ox6.0(H)m, the effective depth:5.0m; A2/O pool as a biological in building a comprehensive pool type,composed of three parts, front-end anaerobic zone and anoxic zones using plug-flow structure, the use of rear section completely mixed aerobic zone structure, design of water:2.0m3/d, divided into two groups to run, stay time:24h (anaerobic3h, and oxygen section3h, aerobic segment18h),dimensions:72.0x60.0x5.7m(H), the effective depth:5.0m, effective volume:20000m3, sludge age:22d, pollution mud load:0.1kgBOD5/(kgMLSS·d), the volume load:0.30kgBOD5/m3·d, the mixture concentration:3000mg/L,gas-water ratio:12:1, sludge return ratio:50to100%. Finally, the sewage treatment plant construction costs and processing costs for detailed analysis.Sewage treatment plant is stable, run data show that the BOD5,COD has better removal.The average effluent COD concentration in the58mg/L,the average removal rate of88.4%;BOD5 average of14.2mg/L,the average removal rate of92.9%;two indicators to achieve"urban sewage treatment plant emission standards"(GB18918-2002),a class B standard,and with high shock load capacity.In nitrogen and phosphorus removal,the influent NH3-N is20mg/L,effluent NH3-N is5.55mg/l,NH3-N removal rate of72%;average influent TP2.0mg/L, the effluent TP average of0.9mg/l,TP removal rate of55%.Effluent N,P index has reached a Class B standards.To A2/O process at the core of the mechanical prc-treatment-acidification-A2/O biological treatment-secondary settling tank-contact disinfection combined process for waste water treatment chemical industry park, the adjustment of process parameters is successful. Effluent target to meet the design requirements.
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