Electrokinetic-assisted membrane photobioreactor (EK-MPBR) for municipal wastewater treatment

Abstract

Membrane technology and phycoremediation, which utilizes algae for nutrient removal, are two major emerging technologies for wastewater treatment. Membrane photobioreactors (MPBRs) integrate these technologies and provide promising technology to render wastewater for reuse in the industrial or agricultural domains. One of the main current limitations of this technology is membrane fouling, and developing a proper technique to address this issue in MPBRs has remained a gap in this sector. With the major aim of alleviating membrane fouling in MPBRs, this study modified the design of the current MPBRs to utilize an electric field. Using graphite sheet as anode and stainless steel mesh as simultaneous membrane support and a cathode on each side of the membrane module was developed to ameliorate membrane performance. This novel design helps to repel biomass from the membrane surface with the charge introduced by a low voltage direct current (DC) electric field. The membrane performance of the electrokinetic-assisted MPBR (EK-MPBR) as well as the biological performance of this recently developed technology, have been investigated. Synthetic municipal wastewater was treated by an EK-MPBR and ran in parallel with a control MPBR for 49 days, where EK-MPBR demonstrated significant improvement in terms of membrane fouling inhibition with 50% less fouling frequency. Considerable enhancement in phosphorus (P) removal was another advantage of the EK-MPBR compared to the control MPBR with the EK-MPBR having 56% better P removal. Involved electrokinetic phenomena such as electrophoresis, electroosmosis, and electrochemical reactions contributed to the performance of EK-MPBRs in terms of cell size reduction, dewaterability, and bacterial growth and agglomeration inhibition, respectively, leading to change in algal morphology. [...]