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Fate of NaClO and membrane foulants during in-situ cleaning of membrane bioreactors: Combined effect on thermodynamic properties of sludge
- Zhang, Haifeng, Sun, Ming, Song, Lianfa, Guo, Jingbo, Zhang, Lanhe
- Biochemical engineering journal 2019 v.147 pp. 146-152
- cleaning, filtration, fouling, hydrophobicity, membrane bioreactors, polymers, sludge, sodium hypochlorite, thermodynamics
- 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.