Study on anaerobic/aerobic membrane bioreactor treatment for domestic wastewater.

A 69-day experimental study was conducted to investigate the treatment process of municipal wastewater using submerged membrane bioreactor technology. The results show that the average removal rate of COD and BOD5 were over 90%. The removal rate of NH3-N was 99% and the concentration of effluent NH3-N was below 0.5mg/L; because of the high DO value in the denitration sect, the denitrobacteria was restrained and the effluent TN value was high, but the removal rate of TN can also reach 80%; the removal of TP was due to sample sludge and microorganism growth. The viscosity of sludge was not increasing with the sludge concentration, it was stabilized at 2.1 mPa·s.The sludge settling ratio (SV30) and sludge volume index (SVI) were increased because soluble microbial products (SMP) and extracellular polymers (ECP) accumulated in the reactor during the course of the experiment, mixed liquor volatile suspended solids (MLVSS) and mixed liquor suspended solids (MLSS) fell slightly. The average diameter of sludge decreased in the course of the experiment, the diameter range was from 49.58 μm to 24.96 μm during the 69-day operation, and there was no trace of contamination membrane, illustrating that the PVDF flat sheet membrane manufactured by TORAY, Japan, had the ability to resist contamination.