The combination of KMnO4 oxidation and polymeric flocculation for the mitigation of membrane fouling in a membrane bioreactor

Abstract

KMnO4 oxidation combined with polyelectrolyte (K530CF) flocculation was investigated to mitigate membrane fouling in a membrane bioreactor. The optimum dosages of chemical additives in order to enhance the removal of soluble microbial products (SMPs) were determined. This method was able to reduce the concentration of COD in the effluent to 57.1% and 51.1% lower than those in the experiments in the absence of chemical flocculants and in the presence of polyelectrolyte, respectively. NH3-N removal was improved by combining KMnO4 and K530CF. When KMnO4 was used along with polyelectrolyte, the zeta potential was neutralized to a greater extent which resulted in an improvement in the flocculation process which subsequently increased the size of the flocs. It was also observed that the SMP of the mixed liquor decreased through entrapment into formed flocs and adsorption by manganese dioxide particles. Increase of the particle size and reduction of the SMP compounds together lead to the reduction of the cake layer resistance. When compared to the experiments in the absence of chemical additives and with polyelectrolyte, KMnO4 in conjunction with polyelectrolyte increased the membrane operating time by about 4 and 2.7 times, respectively. These findings confirmed that KMnO4 along with polyelectrolyte significantly reduced membrane fouling.