The Application Research Of Anaerobic-aerobic-contact Filtration Process To Treat Sugar Refining Wastewater

With the rapid development of the economy, the emission of industrial wastewaterhas been increasing year by year in China. Untreated or substandard wastewater whichis discharged into the river，it will inevitably lead to pollution of the water environmentand even the destruction of the ecological environment. Along with the vigorous growthof population and per capita GDP and the state encourages the development of the sugarindustry, our country’s production and consumption of sugar will grow rapidly, thus thesugar industry has a broad development prospects. The rapid development of sugarindustry will inevitably produce a lot of sugar wastewater, which has become one of theserious industrial pollution sources. Therefore, it is very important to treat sugarwastewater effectively.The sugar industry produces raw sugar, finished sugar and refined sugar with rawmaterials such as sugar-cane, sugar-beet and other crops. Sugar refining wastewater isgenerated by the process of raw sugar refining, and its characteristic (CODconcentration between220~8300mg/L, good biodegradability and low nitrogencontent.etc) is not same with ordinary sugar wastewater. So it has pratical value andtheoretical significance to master the water quality of sugar refining water andeffectively treat sugar refining wastewater.Currently, sugar wastewater treatment process is various, but the treatment processfor raw sugar refining wastewater from the process of raw sugar refining is uncommon.Based on the background, we are entrusted by the Shandong Rizhao MunicipalEnvironmental Protection Institute, according to the wastewater quality and quantityoffered by the Rizhao Lingyunhai Sugar Group Co, Ltd. of Shandong Province,combining with the project research result of Department of Science&Technology ofShandong province(J09LB14) and Qingdao Municipal Science and TechnologyCommission(12-1-4-4-(5)-jch) research results, finally, we selected the combinedprocess of “anaerobic-aerobic-contract filtration”. According to the wastewater offeredby the the Rizhao Lingyunhai Sugar Group Co, Ltd,research group carried out a series of work including treatment process design, on-site construction guidance, experimentaldebugging and operation and adjustment At last, the research projects passed theacceptance.In the combined process of “anaerobic-aerobic-contract filtration”, the anaerobicprocess use the circulation-added internal circulation reactor, the aerobic process use theefficient reactor with double aeration and double sludge-layer filtering, and the contractfilter process by silica sand filter. We explore the feasibility and stability of treatingapplications sugar refining wastewater by the operation of the combined process. Werecheck the main process parameters and streamline relation in the operation by monitorand analyze the quality of influent and effluent. After101days of experimentaldebugging, the effluent has met the relevant standards of reuse. The main conclusions asfollows:1. By taking sugar refining wastewater as the research object,“circulation-addedInternal Circulation-Efficient reactor with Double Aeration and Double Sludge-layerFiltering” realized the stable operation under the condition of low and impact load. Atlast, the effluent concentration of COD was between54~90mg/L, the average removalrate of COD could reach92%in average. The effluent concentration of ammonianitrogen was between1.3~2.8mg/L, and the average removal rate of could reach91%atlast.2. Under the condition of the big different between experimental water quality andquantity and the design specifications, the volume loading of circulation-added ICreactor could reach4.21kg COD/(m3d) relying on the flocculent sludge. And thevolume loading of reactor could reach8.75~9.57kgCOD/(m3d) in the case of impactload. At last, the effluent concentration of COD was200mg/L or so, the effluent ofconcentration VFA was between191~224mg/L, the average removal rate of COD couldreach about71%. The reactor had certain removal efficiency the ammonia nitrogen, andthe average removal rate could reach27%at stage of stable operation.3. The average removal rate of COD could reach36%in average when the effluentof “circulation-added Internal Circulation-Efficient reactor with Double Aeration andDouble Sludge-layer Filtering” flows into the silica sand filter, and the effluent concentration of COD mainly concentrated in43~60mg/L. If adding coagulant withsuitable quantity in the silica sand filter, the average removal rate of COD could beimproved to51%through contact filtration, and the effluent water which was clear,colour and transparency were lower, which has a good supportability for reuse. Both theeffluents can reach the regulations of “Water Pollutants integrated Emission Standard inShandong Province Peninsula Basin”.4. It shows that the combined process of “circulation-added Internal Circulation-Efficient reactor with Double Aeration and Double Sludge-layer Filtering-silica sandfilter” has good treatment effect for sugar refining wastewater. The effluent not onlyreached the regulations of “Water Pollutants integrated Emission Standard in ShandongProvince Peninsula Basin” and its amendment, but also met the needs of factory’sreclaimed water reuse. Meanwhile, the combined process runs stable, adjusts measuresto local conditions, and has lower operating costs and energy consumption.5. When the process adjusted for unilateral running, it has showed good removalefficiency: the effluent concentration of COD stabilizing at18~32mg/L, the removalrate of COD ranging from92~94%, and the effluent concentration of ammonia nitrogenstabilizing at0.14~1.2mg/L.