In this study, the fate of sodium hypochlorite (NaClO) and detached membrane foulants and their impacts on the thermodynamic properties of raw sludge were investigated in a membrane bioreactor (MBR). It was found that about 20.3% of the total NaClO was potentially released into the bulk sludge, which significantly altered the raw sludge surface properties, such as a reduction in the number of surface electron donor components (γ−) and an increase in surface hydrophobicity. After exposure to NaClO, the treated sludge had a higher adhesive and cohesive propensity compared to the raw sludge. Based on the extended Derjaguin-Landau-Verwey- Overbeek (XDLVO) theory and the batch filtration test results, the detached foulants potentially aggregated with the treated sludge and form the reconstructed sludge. The reconstructed sludge had a high protein (PN) level in the extracellular polymeric substances (EPS), with a higher membrane fouling potential compared with the raw sludge.
- Extracellular polymeric substances
- In-situ cleaning
- Interactions energy
- Membrane bioreactor
- Membrane foulants