Nonwovens Bioreactor For Domestic Wastewater Treatment

In recent years, membrane bioreactor (MBR) has been widely used in wastewater treatment to achieve higher effluent quality, which is often difficult to be effectively met by conventional activated sludge process. The advantages of MBR are a high mixed liquid suspended solids (MLSS) concentration, producing higher rate of removal of biological oxygen demand (BOD) and chemical oxygen demand (COD), a lower excess sludge production and the production of treated water can be reused. Membrane bioreactor has been developing for several decades and always broadening its application fields, and has attracted more and more attention. Capital costs of the membrane bioreactor process are substantially influenced by the membrane cost, which has restricted the practical application of the membrane bioreactor in large scale. Nowadays in the world, membrane filtration module is in the situation of high performance with high price and low price with poor performance. A new type submerged membrane bioreactor with the nonwovens as the filtration module was designed for solving this problem. The nonwovens is produced in domestic corporation, it is of the advantage of low price which is only 1/30 compared with the market price of the conventional hollow membrane.The paper investigated the treatment performance of simulated domestic wastewater with nonwovens bioreactor, almost all effluent water quality can meet the national criterion of reclamation water except that bacteria is needed to be disinfected. The results showed that SS could be removed completely; the effluent COD, BOD₅ and NH₄⁺-N were less than 20 mg·L^-1, 10 mg·L^-1, and 1.5 mg·L^-1, respectively.In order to optimize the designing parameters of nonwovens bioreactor, for its wide application in wastewater treatment, the factor that affects the effluent treatment efficiency and the factor that affects the stable operation of nonwovens bioreactor were analyzed in this paper. The performance of synthetic domestic wastewater treatment was evaluated in the nonwovens bioreactor with different pore diameter nonwovens as filtration material at same operating conditions. The optimal designing parameters are shown as following:(1) For nonwovens bioreactor with gravity outflow, the critical pressure was about 30cm water head drop and the critical flux was about 10L/m²Â·h. The appropriate aeration intensity of 3μm nonwovens bioreactor at the activated sludge concentration of 4000 mg/L was 1.0 m³/h.(2) For nonwovens bioreactor with pump suction operation, HRT was more than 5.4h, 6h was recommended, MLVSS concentration in nonwovens bioreactor should be kept at 9000...