Membrane fouling of hybrid submerged membrane bioreactor (hMBR) in treating municipal wastewater

A hybrid submerged membrane bioreactor (hMBR) with porous polyvinylchloride carriers was used to treat the municipal wastewater, and a parallel MBR (pMBR) without the porous polyvinylchloride carriers was run as a contrast. The results of the chemical oxygen demand and nitrogen removal demonstrated that the hMBR process was more efficient than pMBR. Membrane fouling was analyzed by variations of trans-membrane pressure. It is believed that the carriers served to scrub the membrane and adsorb extracellular polymeric substance of the biofilm, therefore, extending the operation time of the hMBR membrane fouling. The analysis of molecular-based methods showed that the two MBRs had the same kinds of gene express forms, but the pMBR had more total bacteria than the hMBR to form biofilm on the membrane, which suggested that more serious membrane fouling in the pMBR than in the hMBR.