Research of synergistic effect of magnetic powder and biosurfactant in pollutants removal and membrane fouling alleviation

Abstract

This study constructed a rhamnolipid-magnetic membrane reactor (RL-MMBR) coupled system to investigate the effects of RL and magnetic powder on membrane fouling alleviation and wastewater treatment efficiency. The optimal concentration was determined by comparing the effects of different concentrations of RL and magnetic powder as well as single and mixed injection on the operation performance. The effects of RL and magnetic powder on pollutant degradation and membrane fouling were investigated at the optimum concentration (300 mg/L RL + 120 mg/L Fe3O4). It was found that the time for TMP to reach 30 kpa in RL-MMBR was 7 days longer than that in CMBR. In the RL-MMBR, the concentration of SMP declined from 13.22 mg/L to 6.75 mg/L and the concentration of LB-EPS decreased from 14.37 mg/L to 7.95 mg/L, and their concentration in RL-MMBR was gradually lower than that in CMBR. But the concentration of TB-EPS in RL-MMBR was always greater than that of CMBR. The sludge particle size in RL-MMBR was gradually larger than that in CMBR. The overall COD removal rate of RL-MMBR (95 %-98 %) was better than that of CMBR (91 %-95 %). The synergistic effect increased the species abundance and diversity of microorganisms in the sludge mixture, but reduced the enrichment of microorganisms on the membrane, especially reduced the adhesion of high-viscosity microorganism Proteobacteria to the membrane. The RL-MMBR coupled system improved the degradation efficiency and alleviated the membrane fouling. In addition, the direct dosing of the agent increased the convenience of operation, the recycling of the magnetic powder reduced the operating cost, and the reaction had no secondary pollution. This provided new ideas and theoretical guidance for solving membrane fouling problems in MBR treatment of domestic sewage.