Fouling control in ceramic nanofiltration membranes during municipal sewage treatment

• Published in: Separation and purification technology Vol. 237; p. 116373
• Main Authors: Kramer, F.C., Shang, R., Rietveld, L.C., Heijman, S.J.G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.04.2020
• Subjects: Ceramic nanofiltration; Forward flush; Fouling control; Municipal sewage; Reaction based precoat; Fouling control; Ceramic nanofiltration; Municipal sewage; Reaction based precoat; Forward flush
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2019.116373

•Alternative fouling control methods are required for application of sewage treatment using ceramic NF.•This paper introduces reaction based precoat as fouling control method for ceramic NF membranes.•Reaction based precoat method enables detachment of fouling layer from membrane surface.•The reaction based precoat method was compared with hydraulic backwash and forward flush.•Reaction based precoat method has potential for removal of fouling from ceramic NF treating sewage. Using ceramic nanofiltration membranes for treatment of municipal sewage is upcoming. However, the knowledge on fouling control methods for this application are very limited. The most commonly used fouling control method, chemical cleaning, has disadvantages. Chemical cleaning negatively impacts (i) the glass seal layer of tubular ceramic nanofiltration membranes and (ii) the environment, especially when using sodium hypochlorite for removal of organic fouling. Therefore, the use of chemical cleaning should be limited as much as possible. In this research, first, the well-known fouling control methods for polymeric micro- and ultrafiltration membranes, were studied on ceramic nanofiltration membranes: hydraulic backwash and forward flush. Second, a precoat method was combined with a chemical reaction to aid the detachment of the formed cake layer. In this method, a precoat layer was filtered atop of the membrane surface before the start of filtration. The precoat layer then acts as a barrier between the foulants and the membrane surface. After filtration, the precoat layer reacts with the cleaning reagent underneath the fouling layer to enable fast removal of fouling. Results showed that hydraulic backwash was not effective to be used for this type of membranes. Forward flush was able to maintain a higher flux but the relative production downtime was high. Reaction based precoat was most effective in maintaining a high flux and resulted in the highest net water production. Two reaction based precoat methods were tested of which the reaction of calcium carbonate with citric acid was more effective than a Fenton reaction.