A systematic analysis of fouling evolution and irreversibility behaviors of MBR supernatant hydrophilic/hydrophobic fractions during microfiltration

摘要: Abstract Membrane fouling remains a challenge for membrane bioreactor (MBR) application to wastewater treatment. The hydrophilic/hydrophobic organics present in MBR sludge supernatant form an important part of foulant. Their effects on evolution and irreversibility were systematically investigated this study. organics, as fractionated into hydrophilic substances (HIS), hydrophobic acids (HOA), bases (HOB), neutrals (HON), subjected experiments using six microfiltration membranes covering the size range 0.1–0.45 µm with varied hydrophobicity. Modeling methods applied quantitatively characterize dynamic process consisting initial pore blocking subsequent gel layer stages. results demonstrated importance foulant concentration evolution: apparent rate same followed order HIS>HOA⪢HOB>HON, whereas became HOA>HIS normalization give intrinsic propensity (across stage) well specific resistance (for stage). Foulant–membrane interactions (i.e. adsorption exclusion) foulant–foulant interaction (polymer–metal–polymer complexation) identified key mechanisms at stage respectively, properties hydrophobicity, molecular carboxylic complexing groups closely involved interactions. Additionally, also factors affecting behaviors fractions, suggested by combined impact hydrophobicity propensity, decisive role irreversibility.