Pollutants Removal Effect and Membrane Fouling Alleviating by an Improved Submerged Membrane Bioreactor for Domestic Wastewater Treatment

The effect of an improved membrane bioreactor (IMBR) on COD, NH₃-N and TN removal and membrane fouling alleviating was investigated through a comparative study with a traditional submerged membrane bioreactor (SMBR). The variations of trans-membrane pressure (TMP), concentration of mixed liquid suspend sludge (MLSS) and extracellular polymeric substance (EPS) was also conducted through the long-term operation. The results showed that the removal efficiency of COD and NH₃-N by the IMBR was similar with that of the SMBR in that both the effluent COD were less than 30 mg/L and the NH₃-N were less than 2 mg/L, while the removal efficiency of TN by IMBR was 75%, which was much better than that of SMBR. The MLSS and EPS concentration in SMBR were basically identical with that of IMBR´s biotic zone. They were increased with the operation time, but they were significantly decreased in IMBR´s membrane zone than that of SMBRs´. The IMBR was more capable of alleviating membrane fouling, and it had been cleaned only twice while the SMBR who had been cleaned 5 times during the period of about 90 days laboratory performance.