Nano chitosan to sludge ratio modulates fouling mitigation in electric field-assisted membrane bioreactors

Abstract

Membrane fouling poses a significant challenge in applying membrane bioreactors (MBRs), despite advantages of the MBRs, such as superior effluent quality, energy efficiency, and compact design for wastewater treatment. This study explores the relationship between nano chitosan-sludge ratios and fouling control, presenting innovative solutions to this issue. The laboratory-scale aerobic electric field-assisted MBR (E-MBR) consisted of four electrodes (two pairs of stainless steel plates) submerged in the mixed liquor of a flat membrane bioreactor were used. Various chitosan-sludge ratios (0, 0.2, 0.3, and 0.4 g/L) were tested with a solid retention time (SRT) of 25 days and a hydraulic retention time (HRT) of 6 h. Long-term experiments revealed that a nano chitosan dosage of 0.3 g/L (E-MBR0.3) was the optimal configuration, achieving an impressive 100 % membrane recovery ratio after 62 days of operation. This approach successfully eliminated pore blockages caused by small sludge particles, decreased the concentrations of proteins and humic acids, and improved effluent quality. E-MBR0.3 enhanced the performance index by 79 % compared to the control MBR while displaying minimal fouling and a favorable sludge particle size distribution. The results underline the economic and operational advantages of reduced cleaning frequency and maintenance, paving the way for cost-effective and sustainable wastewater treatment. By leveraging the synergistic effects of electric fields and appropriate nano chitosan concentration, this study establishes a new benchmark for advancing MBR technology, offering robust solutions to address water scarcity and environmental challenges.