Effect of magnetic powder on membrane fouling mitigation and microbial community/composition in membrane bioreactors (MBRs) for municipal wastewater treatment

Abstract

This study aims to investigate the usefulness of magnetic powder addition in membrane bioreactors (MBRs) for membrane fouling mitigation and its effect on microbial community and composition. The comparison between the two MBRs (one with magnetic powder (MAS-MBR) and one without magnetic powder (C-MBR)) was carried out to treat synthetic municipal wastewater. Results showed that bioflocculation and adsorption of magnetic powder contributed only minimally to membrane fouling mitigation while the slower fouling rate might be ascribed to magnetic bio-effect. The macromolecules (larger than 500 kDa and 300-500 kDa) of soluble microbial product from the MAS-MBR were reduced by 24.06% and 11.11%, respectively. High-throughput sequencing demonstrated the most abundant genera of biofilm sludge indicated lower abundance in bulk sludge from the MAS-MBR compared to the C-MBR. It is possible that less membrane fouling is connected to reductions in large molecules and pioneer bacteria from bulk sludge.

Effects of a low-strength magnetic field on the characteristics of activated sludge for membrane fouling mitigation

“…The TMP in the M-MBR reached above 50 kPa until day 17 with an average fouling rate of TMP of 3.01 kPa d À1 , while the TMP in the M-MBR reached above 50 kPa until day 24 with an average fouling rate of TMP of 2.06 kPa d À1 . A similar result was reported by Liu et al5 The signicantly low fouling rate in the M-MBR indicates that integrating the magnetic eld unit into an MBR system is a promising method to alleviate the negative effects of membrane fouling, thereby prolonging the operation periods for MBRs.3.2 Zeta potential and particle sizes of mixed liquor colloid…”

“…Magnetic bio-effect is considered to be the main factor in mitigating membrane fouling when magnetic powder is added in membrane bioreactors (MBRs) for membrane fouling mitigation. 5 Wang et al 6 reported that magnetic powder improved the dehydrogenase activity, enhanced the biomass growth, and exhibited good performance in the mitigation of membrane fouling. Chen et al 7 found that there are a variety of microbial species in the reactor and that the membrane fouling rate can be decreased by adding magnetic particles to the MBR.…”

Membrane processes

“…Magnetic powder addition as a way to mitigate membrane fouling in MBRs was investigated by Liu, Liu, Li, et al (2018). Results showed that bioflocculation and adsorption of magnetic powder were only minimally effective at fouling mitigation, but the magnetic bio‐effect resulted in a slower fouling rate.…”

Systematic insight into the short-term and long-term effects of magnetic microparticles and nanoparticles on critical flux in membrane bioreactors

“…Considering the responsiveness of magnetic particles to the magnetic field, they can be easily separated, reactivated and reused, thus MAS process is cost-efficient. Recently, it also displayed great potential for mitigating membrane fouling in MBRs [8]. Wang et al [9] found that adding magnetic particle could effectively alleviate membrane fouling by encouraging microbes to produce less membrane foulants.…”

“…Wang et al [9] found that adding magnetic particle could effectively alleviate membrane fouling by encouraging microbes to produce less membrane foulants. Liu et al [8] found that magnetic bio-effect could significantly mitigate membrane fouling by reducing the amounts of macromolecules and pioneer bacteria from bulk sludge. Although MAS process has been extensively investigated for improving biomass growth and pollutants removal [10], the information on mitigating fouling in MBRs is still limited.…”