Gel-fouling on the microfiltration membrane for wastewater reclamation and its suppression by using electric fields: from the viewpoints of spatiotemporal and force analysis.

Microfiltration membrane technology holds promising applications in addressing contemporary water resources and environmental challenges for wastewater treatment, but membrane fouling remains a pivotal bottleneck hindering its advancement, especially that it is still unclear for the formation of gel-fouling on the membrane surface, from its characteristics to development process. Applying electric field onto the microfiltration membrane filtration to control membrane fouling has the advantages of safety, green and easy-manipulation. This study explored the gel-fouling characteristics of typical foulants such as sodium alginate (SA), bovine serum albumin (BSA), humic acid (HA) filtered by polyvinylidene fluoride (PVDF) microfiltration membrane, and its dynamic development. Hermia model was introduced to simulate and quantify the membrane flux, and it was observed that SA resulted in the most severe gel-fouling. Gel-fouling could be formed with the start of filtration, lasted for a period of time, and then to produce a dense fouling layer on the membrane surface. It is then suggested that the fouling control time should be synchronized with the start of filtration. Effects of different factors on the electric field control for gel-fouling were investigated, and the applied electric field in the same direction with permeation was better than that under the opposite one. When filtering 30 mg/L SA solution under an electric field, gel-fouling can be well controlled. Force analysis showed that enhanced electrophoretic force was effective in alleviating membrane fouling. The obtained results would advance the understanding of the gel-fouling mechanisms in microfiltration technology for wastewater treatment, particularly focusing on its spatiotemporal development. Moreover, by leveraging electric fields to regulate fouling, this strategy offers a scientific foundation and technical backbone for membrane separation that strived for low energy consumption and high operational efficiency.