Coupling in-situ ozonation with ferric chloride addition for ceramic ultrafiltration membrane fouling mitigation in wastewater treatment: Quantitative fouling analysis

Membrane fouling is still a critical problem restricting membrane applications in wastewater treatment. Herein, for the first time, the single and synergistic effects of in-situ ozonation and ferric chloride addition on membrane filterability of mixed liquor and ceramic ultrafiltration (UF) membrane fouling in wastewater treatment were quantitatively investigated by statistical analysis including factor analysis, redundancy analysis and canonical correlation analysis. The filterability score of mixed liquor had very strong positive linear correlation with total membrane fouling resistance. Both the membrane filterability of mixed liquor and the ceramic membrane fouling mitigation performance followed the order: in-situ ozonation (10 mg/L)/ferric chloride addition (45 mg/L) > ferric chloride addition (45 mg/L) > in-situ ozonation (10 mg/L) > control. Specifically, ferric chloride addition (45 mg/L) contributed to 45.8% of membrane fouling mitigation as a result of 52.2% of improvement of membrane filtration environment. In-situ ozonation (10 mg/L) contributed to 26.6% of membrane fouling mitigation as a result of 28.6% of improvement of membrane filtration environment. The combination of in-situ ozonation (10 mg/L) and ferric chloride (45 mg/L) further contributed to 26.6% of the mitigation of iron-related membrane fouling. O3 in the case coupling in-situ ozonation with ferric chloride addition reduced the accumulation of Fe and mixed liquor suspended solid (MLSS) on the membrane surface and mitigated membrane fouling in comparison to the case with only ferric chloride addition. Our results demonstrated that the combination of in-situ ozonation and Fe dosing with ceramic membrane filtration in wastewater treatment could achieve the synergistic effect in terms of the improvement of membrane filterability of mixed liquor and mitigation of membrane fouling.