| With the rapid development of dairy industry in our country, dairy wastewater pollution problems are increasing. The dairy wastewater has large fluctuations of quality and quantity, the concentration of COD, BOD is high and it is well biodegradable. In this paper, the project for Harbin HuaYi food factory sewage treatment design has an important significance for the regional water environment protection in Harbin and the process achievement can provide references for other similar projects.Estimate the quality of domestic sewage according to "water supply and drainage design manual", take the real-time monitoring of wastewater to determine the influent water quality, and analyzes it’s characteristics, Determine the effluent water quality by the national sewage discharge standards and the requirements of the local government. To determine the best sewage treatment process from the influent and effluent water qulity of the sewage, technical and economic comparison. Design and calculate for each structure treatment process, and draw related processes. Monitoring of the effluent water quality, The effluent water reach the design requirements.Determine the design flow is 500m3/d. According to the wastewater quality monitoring date, Determine the indicators of the wastewater COD, BOD5, SS, animal fats and pH is 2500mg/L,1500mg/L,500mg/L,50mg/L and 6-9. Effluent water quality should reach "comprehensive pollutant emission standards "(GB8978-1996) three level standards. Combined with the actual situation of Harbin HuaYi food factory sewage treatment and the design requirements, Wastewater treatment is based on wastewater quality,design requirements and domestic application practices. Grid and regulation pool as pretreatment, anaerobic-aerobic combined treatment process as first and second level treatment, anaerobic treatment using hydrolysis acidification, aerobic treatment using biofilm process, determine biological contact oxidation as biofilm process by technical comparison between aerated biological filter aeration and biological contact oxidation. Considering the effect on aerobic treatment by tiny suspended solids which produced in hydrolysis acidification, using air flotation to remove the tiny suspended solids in the sewage on the premise that the costs of running after hydrolysis acidification. Combination of hydrolysis acidification-air flotation-biological contact oxidation process as ultimately determine process. For the sludge produced by high concentration of organic wastewater after biological treatment, Using gravity concentration after belt pressure filter, the sludge after pressure can use as raw materials for efficient biological fertilizer. Considering the long-term development, grid and regulation pool as pretreatment, choose circulating harrow rack cleaner, model:XQ-0.30×1.0, clearance:3mm, size:L×B×H=1.2m× 0.4m×1.0m; regulation pool, the residence time:4.5h, size:L×B×H=7.0m×4.5m ×3.5m. Hydrolysis acidification-air flotation-biological contact oxidation process as biochemical treatment, hydrolysis acidification pool, the residence time:5h, size:L× B×H=6.7m×4.5m×3.5m+2.3m×1.8m×3.5m; air flotation pool, size: (including platform and stairs) L×B×H=5.923m×2.68m×2.72m; biological contact oxidation pool of three level, the residence time:13.4h, size:L×B×H= 6.0m×5.0m×3.5m;Using concentration poor and belt pressure filter to deal with the sludge, sludge quantity every day:32m3/d, concentration poor size:L×B×H=3.0m×3.1m× 2.0m, the bucket volume:2.2m3; belt machine of concentrating and dewatering, model:ND-750, filter width:W=750mm. Harbin HuaYi food factory sewage treatment running stable, BOD5 of effluent:281mg/L, the rate of average removal: 81.3%; COD of effluent:469.1 mg/L, the rate of average removal:81.2%; SS of effluent:369.7mg/L, the rate of average removal:26.1%. Operation datas show that the removal efficiency of each pollutant is good, the water quality of the effluent can reach even better than the design standard and has resistance to impact high load capacity effluent.Combination of hydrolysis acidification-air flotation-biological contact oxidation process is suitable for the treatment of dairy wastewater, effluent water quality can meet "comprehensive pollutant emission standards "(GB8978-1996) three level standards. Effluent water quality of the sewage meet the design requirements. Each structure treatment process is reasonable, the construction project with a total investment of 2.5131 million and it can provide suggestions and references for other related projects which scale is small and water quality is similar. |
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