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Comparison of sewage plant processes 1. Sewage plant construction scale categories (measured in sewage treatment capacity, unit: 10,000 m3/d) Category I: 50 ~ 100, Category II: 20～50, Category III: 10～20, Category IV: 5～10, Category V: 1～5. 2. Sewage treatment level primary treatment (including enhanced primary treatment): Treatment process based on precipitation ； secondary processing: Treatment technology based on biological treatment ； Depth processing: Further removes contaminants that secondary treatment cannot completely remove. 3. The construction content of the sewage plant includes production facilities for sewage treatment and sludge treatment, auxiliary production supporting facilities, production management and living facilities. Production facilities include: ①, primary treatment sewage plant: Primary sewage treatment and sludge treatment facilities. Primary sewage treatment generally includes slag removal, sewage lifting, grit settling, sedimentation, disinfection and effluent discharge facilities. When strengthening the primary treatment, facilities such as pharmaceutical dosing can be added. Sludge treatment generally includes facilities such as sludge storage and lifting, sludge thickening, sludge anaerobic digestion systems, sludge dewatering and sludge disposal. ②, secondary treatment sewage plant: Including sewage secondary treatment and sludge treatment facilities. Secondary sewage treatment can include all or part of the items listed in primary sewage treatment and biological treatment system facilities according to the characteristics of the process. The content of sludge treatment can be the same as that of the primary sewage plant. The stabilization of sludge can be treated by methods such as anaerobic digestion, aerobic digestion and composting. ③. The advanced sewage treatment plant should be optimized and combined by the following unit technologies.: Flocculation, precipitation (clarification), filtration, activated carbon adsorption, ion exchange, reverse osmosis, electrodialysis, ammonia stripping, ozone oxidation, disinfection, etc. 4. Selection of sewage treatment technology The biological treatment technology for secondary treatment of urban sewage can be divided into two categories: activated sludge method and biofilm method. The activated sludge process mainly includes the following processes: Traditional biological treatment ； Pre-anoxic zone (biological selector) ordinary aeration biological treatment ； Anoxic and aerobic denitrification biological treatment ； Anaerobic and aerobic phosphorus removal biological treatment ； Anaerobic, anoxic and aerobic biological treatment for nitrogen and phosphorus removal ； Sequential batch (SBR) biological treatment ； Oxidation ditch biological treatment ； AB method biological treatment. Biofilm methods mainly include biological filters and biological contact oxidation methods. The selection of sewage treatment technology should be based on the quality and quantity of sewage, the environmental function requirements and categories of receiving water bodies, and combined with the actual local conditions, and should be determined after technical and economic comparisons. Priority should be given to mature treatment processes with low energy consumption, low operating costs, low investment, small footprint, and convenient operation and management. In order to make the selected sewage treatment process meet the actual requirements of sewage water quality and treatment level, small tests can be conducted before the construction of the sewage plant to determine the relevant process parameters. 5. The determination of sewage treatment levels and discharge standards should be based on factors such as sewage water quality, total pollutant control standards of receiving water bodies, categories and use functions of water bodies, and based on environmental impact assessment and technical and economic comparisons. The appropriate sewage treatment level can be selected according to different requirements for the degree of sewage treatment. When the removal rates of suspended solids and five-day biochemical oxygen demand are required to reach 40% to 55% and 20% to 30% respectively, primary sewage treatment can be used ； When the removal rate of suspended solids and five-day biochemical oxygen demand is required to be not less than 65%, secondary sewage treatment can be used ； When the removal rate of pollutants is between the primary treatment and secondary treatment of sewage, a comprehensive technical and economic comparison should be made, and enhanced primary treatment by adding chemicals can be used. ； When the requirements for phosphorus removal are high and biological phosphorus removal cannot meet the requirements, chemical phosphorus removal can be supplemented. ； When the effluent from the sewage plant is reused, appropriate depth treatment should be carried out according to the purpose of use. The effluent from the sewage plant is not allowed to be discharged into the Class I and Class II waters specified in the "Surface Water Environmental Quality Standard" (GHZB1-1999) and the Class I sea areas specified in the "Sea Water Quality Standard" (GB3097). The water quality of the effluent from the sewage plant that is discharged into Class III waters (except for designated protected areas and swimming areas) stipulated in the "Surface Water Environmental Quality Standard" (GHZB1-1999) and the Class II sea areas stipulated in the "Sea Water Quality Standard" (GB3097) shall comply with the provisions of the first-level discharge standards in the "Integrated Wastewater Discharge Standard" (GB8978-96). The water quality of sewage plant effluent discharged into Class IV and V waters specified in the "Surface Water Environmental Quality Standard" (GHZB1-1999) and into Class III sea areas specified in the "Sea Water Quality Standard" (GB3097) shall comply with the provisions of the secondary discharge standards in the "Integrated Wastewater Discharge Standard" (GB8978-96). The total amount of pollutants discharged from the effluent of the sewage plant must be less than the total amount of pollutants control standards determined by the environmental planning or environmental impact assessment of the water body. For waters discharged into closed and semi-enclosed waters that are now eutrophic or have the threat of eutrophication, a secondary sewage treatment process with phosphorus and denitrification functions should be selected. 6. Sewage plant sludge disposal Sludge generated from sewage treatment should be properly treated and disposed of. The sludge treatment process should be determined based on comprehensive considerations such as sludge volume, sludge properties, final disposal method, and impact on the natural environment. Conventional treatment processes should be concentration, digestion, and dehydration. The disposal method of sludge should be combined with local conditions and comprehensively determined on the basis of technical and economic analysis. Methods such as disposal with municipal garbage, sanitary landfill, incineration, and use as fertilizer for agriculture or greening can be used. The sludge disposed of should comply with the requirements. * * Current relevant standards. This post was last edited by hesonchang214 on 2009-4-5 11:31 ]