Study On Treatment Of The Diosgenin Wastewater By Membrane Bio-reactor

Wastewater from diosgenin industry is hard to degrade due to its high concentration of organic matter, high content of SO42-, high chroma and so on. A large amount of wastewater above the standards is a serious threat to the safe of the receiving water quality.Along with the gradual increase of discharge standard of pollutants, the environmental issue has become a bottleneck restricting the development of turmeric industry.So far, few of diosgenin wastewater treatment by membrane bioreactor(MBR) have been reported. In this study, the integrated aerobic membrane bioreactor was used to deal with the anaerobic effluent of the diosgenin wastewater UASB treatment process, approached the start-up again of the biological treatment process after seeding due to seasonal turmeric diosgenin production, investigated the removal characteristics of pollutants in the saponin wastewater and optimum operating conditions in the MBR treatment system, and analyzed the scaling problem in the running process of the system, thus demonstrated the feasibility of the MBR treatment process and provided references for saponin wastewater treatment projects to meet the new standards.The experiment results show that: in the start-up stage, start-up again is faster than the first start-up, the removal rate of COD, ammonia nitrogen can reach more than 90% after running 10 days; Membrane in the treatment system can intercept organic matter, TP, but can not intercept ammonia nitrogen, nitrate nitrogen and nitrate nitrogen of the wastewater. In the stage of optimum operating parameters, the optimal HRT, temperature, sludge loading and volume loading is 48 h, 25~30℃, 0.3~0.6kgCOD·(kg MLSS·d)-1, 0.5~1.0kgCOD·(m3·d)-1 respectively; the removal rate of COD, ammonia nitrogen can reach more than 90%, 85% respectively, and effluent quality can meet The Discharge Standard of Water Pollutants for Sapogenin Industry(GB20425-2006) and The Discharge Standard of Yam Diosgenin Cleaner Production(DB61/T424-2008) under the optimal conditions; the removal rate of sulfide is over 99%, and effluent quality can comply with the Class A of Integrated Wastewater Discharge Standard(GB8978-1996)(≤1mg·L-1); the sludge concentration of the system is much higher than the traditional activated sludge process, but MLVSS/MLSS(25%~40%) is far lower than the traditional activated sludge process, and the sludge setting change is large. The MBR treatment system whose SV30 is between 95%~98% has poor sedimentation performance of sludge, but which has a little influence on effluent quality, because membrane can intercept mud and water.During the experiment, the reactor had obvious scaling phenomenon, the scale in the inlet pipes mainly is Ca CO3 and elemental sulfur, but for the most part inside the reactor is CaCO3. The flooding water of the reactor has a trend of scaling,and scales seriously. Calcium scale will contain microbes when high calcium content, so that reduce the treatment effect, and at the same time calcium scale increased the content of inorganic components in the sludge of the system. Calcium scale will be steady accumulation within the system due to the longer SRT in MBR, and eventually reduce the treatment effect and stability of the system.