Study And Application Of A Novel Dynamic Membrane Bio-Reactor

Water pollution problem is becoming highlighted at this stage in our country, which seriously affects the function of water body, aggravates the water shortage problem and hampers the development of the national economy. Therefore, in order to improve the water quality and develop the healthy and rapid economy, it is an urgent need to treat the domestic sewage and the industrial wastewater discharged to water body effectively and enhance the reuse of water resource. Specially, the development of efficient sewage treatment and reuse technology is important technical supportThrough the study on selection of coarse pore filter material, control of membrane fouling, and improvement of reactor configuration, a novel internal circulation dynamic membrane bioreactor was developed and used in the treatment of domestic sewage and bleaching liquor from straw-pulp processing.The results of coarse pore filter material selection showed that bolting-silk and single slip surface non-woven fabric were cheap, stable, and easy to be adhered by sludge. When the HRT was 6 h, the dynamic membrane could be formed within 90 minutes. The turbidity of effluent was less than 5 NTU. The average concentrations of COD, ammonia nitrogen, total nitrogen and total phosphorus in effluent were 25.6 mg/L, 1.5 mg/L, 27.5 mg/L and 2.9 mg/L, respectively.Online aeration backwashing in the inverse direction of effluent was carried out to control membrane fouling. The recovery of dynamic membrane was affected by backwashing aeration intensity and backwashing time. When the aeration intensity was 5.6 m~3/(m~2 h) and the backwashing time was 5 min, regeneration of dynamic membrane needed 45 minutes and the backwashing cycle could be stabilized around 15 hours.Internally circulating dynamic membrane bioreactor was designed to enhance the uniform of flow pattern and inhibit membrane fouling. The results showed that the flow pattern was more uniform, and the dead zone rate was only 0.2 %, which was less than that of 7.2 % in conventional dynamic membrane bioreactor. When the HRT was 6 h, the average removal rates of COD, ammonia nitrogen, total nitrogen and total phosphorus were 94.0 %,97.6 %, 49.2 % and 83.7 %, respectively. Meanwhile, the membrane fouling problem had been effectively delayed with the average backwashing cycle around 54.8 hours. The kinetic equation of domestic sewage was v = 2.655/(403.9 + S).Analysis of dynamic membrane structure and function showed that the biomass, dehydrogenase activity and oxygen consumption rate of the activated sludge were substantially higher than that of dynamic membrane. The removal of pollutant mainly relied on activated sludge in the reactor. Dynamic membrane can also remove part of pollutant through biodegradation. Dynamic membrane was mainly composed by filamentous fungi, bacteria, streptococcus and extracellular secretion.Dynamic membrane bioreactor combined with coagulation treatment process was applied in the treatment of bleaching liquor from straw-pulp process in paper making industry. The results showed that COD and chromaticity of the effluent were lower than 120 mg/L and 50, respectively. The effluent quality met the discharge requirement after 2010 of "discharge standard of paper making industry water pollutant in Shandong Province" (DB37/33 6-2003).