Integration of ferrate (VI) pretreatment and ceramic membrane reactor for membrane fouling mitigation in reclaimed water treatment

Ferrate (VI) is a unique and green chemical that can be utilized for oxidation, disinfection and coagulation simultaneously in a single unit without producing by-product. Herein, for the first time, we reported the integrated process of ferrate (VI) pretreatment coupled with ceramic membrane reactor for mitigating membrane fouling in natural reclaimed water treatment. Membrane fouling was effectively mitigated by ferrate pretreatment with the maximum trans-membrane pressure (TMP) reduction of 81.8% achieved at ferrate dosage of 0.15 mM. Moreover, the fouling mechanism changed from intermediate-standard blocking to cake-intermediate blocking with ferrate pretreatment and the contribution of cake layer fouling was significantly diminished with increase of ferrate dosage (<= 0.15 mM). Statistical analysis including redundancy analysis and clustering correlation analysis showed that chemical oxygen demand (COD), dissolved organic carbon (DOC) and polysaccharide were the most important positive factors to R-t with their correlation coefficients above 0.92 while SS and turbidity were the most important negative factors to R-t with their correlation coefficients below - 0.87. Long-term filtration experiments also confirmed the membrane fouling control performance by ferrate with the significant extension of the onset of membrane fouling.