Study of pre-denitrification submerged membrane bioreactor for domestic wastewater treatment

Abstract

This study revealed that membrane fouling rate increased with increasing soluble microbial products (SMP) and extracellular polymeric substances (EPS) concentrations, in which both SMP and EPS concentrations increased with decreasing MCRT. Accumulation of carbohydrates rather than proteins in the mixed liquor supernatant was found to decrease with increasing MCRT. Image analysis of the fouled membrane showed that biofilm formation was the possible cause of membrane fouling. It was also found that high aeration rate of 10 L air/min was able to minimize membrane fouling as compared to the lower aeration rate of 5 and 2.5 L air/min. However at an aeration rate of 10 L air/min, the high DO concentration present in the recycle mixed liquor deteriorated the TN removal efficiency when operating at a recycle ratio of more than 3. A lower aeration rate of 5 L air/min saw an improvement in TN removal efficiency; 63, 80, 84 and 89% for R of 1, 3, 5 and 10, respectively. Further decrease in aeration rate to 2.5 L air/min did not show any significant improvement in the TN removal efficiency.