Dynamic analysis of the membrane fouling process in a submerged membrane bioreactor

Dynamic analysis of the fouling process is very important for effective control of membrane fouling. Under different sludge concentrations and fluxes, the changes of transmembrane pressure, combined with changes of the appearances of the fouled membrane surface were investigated, to dynamically analyze membrane fouling process of a submerged membrane bioreactor. It was found that soluble organic substances were adsorbed on the membrane surface at the early stage of membrane fouling, then the sludge particles deposited on it. Soluble organic foulants contributed little but sludge particles deposited on the membrane surface resulted in a rapid increase of the transmembrane pressure. The higher the sludge concentration and the flux were, the easier it was for the sludge particles to deposit on the membrane surface. The sludge cake layer was reversibly removed through extended aeration without effluent, reduced sludge concentration or prolonged cease time of membrane filtration. Traditional membrane fouling models were applied to analyze the membrane fouling processes, which was consistent with the results of SEM.