Study On Properties Of Integrated Membrane Process With MBR Effluent For Sewage Depth Reuse

The water consumption of thermal power plant is almost 40%of the country's industrial total water demand.However,the water resource in our country is scarce and water pollution has become more and more serious.Therefore,water reuse is an effective way to solve this problem.The most representative and advanced water depth reuse technology is integrated membrane process.Recently,secondary effluent of sewage treatment plant is more often used as raw water and there is still few application example of MBR effluent for depth reuse process.Due to the high-performance membrane separation,the separation efficiency is far better than traditional sedimentation tanks.Suspended solids and turbidity in MBR effluent is close to zero,bacteria and viruses have been substantially removed,which provide a good condition for depth reuse.However,the impact to reverse osmosis membrane of residual COD,NH₄⁺-N and other materials in biological treatment can not be ignored,and the research is based on the background and study for the reliability of the reuse system that use UF-RO integrated membrane process for water depth reuse with MBR effluent in Jinqiao thermal power plant.The study examined the reliability of ultrafiltration-reverse osmosis(UF-RO) integrated membrane process with MBR effluent for water depth reuse as well as the design applicability of the system.According to the MBR effluent water quality and characteristics of the operating system,we determined the status of the UF-RO system and the most reasonable process parameters,analyzed the process performance situation, adjusted and optimized the operation of the reuse process with a view to provide guidance to the actual production.The investigation focused on the system pollution of residual COD,NH₄⁺-N and other materials,determined and optimized the backwashing cycle of ultrafiltration and chemical cleaning cycle of reverse osmosis membrane.The result shows that the production water quality of UF as a pretreatment for reverse osmosis with MBR effluent is stable and isn't impacted with the raw water quality changes;UF-RO technology can effectively remove the suspended solids, colloids,organic compounds,ammonia nitrogen,salts and so on,and the quality of production water has a qualitative leap than the raw water and meets with the depth reuse requirement.When the trans-membrane pressure increases by 10%to 15%form the original membrane flex that they need to have a chemical cleaning.Based on the optimal cleaning method,the membrane flex of ultrafiltration and reverse osmosis are able to return to the initial flux of 98%and 96%.The entire trial proves the reliability of the MBR-UF-RO process for the deep reuse of reclaimed water and lays a foundation to achieve the goal of saving water.