Unveiling the impacts of salts on halotolerant bacteria during filtration: A new perspective on membrane biofouling formation in MBR treating high-saline organic wastewater

Haiyang Lin, Yucai Du, Mengchao Yu, Wenyue Zhang, Weiwei Cai*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

In recent decades, membrane bioreactor (MBR) has been prevalently employed to treat high-saline organic wastewater, where the halotolerant microorganisms should be intensively utilized. However, limited works were devoted to investigating the biofouling characteristics from the perspective of the relationship between halotolerant bacteria and salts. This work filled the knowledge gap by exploring the biofouling formation mechanisms affected by high salinity. The results showed that the amount of negative charge on halotolerant bacteria surface was significantly reduced by high content of NaCl, probably leading to the obvious cell agglomeration. Despite the normal proliferation, the halotolerant bacteria still produced substantial EPS triggered by high salinity. Compared with the case of control without salt addition, the enhanced biofouling development was observed under high-saline conditions, with the fouling mechanism dramatically transformed from cake filtration to intermediate blocking. It was inferred that the halotolerant bacteria initially adhered on membrane created an extra filter layer, which contributed to the subsequent NaCl retention, resulting in the simultaneous occurrences of pore blockage and cake layer formation because of NaCl deposition both on membrane pores as well as on biofilm layer. Under high-saline environment, remarkable salt crystallization occurred on the biofilm layer, with more protein secreted by the attached halotolerant bacteria. Consequently, the potential mechanisms for the enhanced biofouling formation influenced by high salinity were proposed, which should provide new insights and enlightenments on fouling control strategies for MBR operation when treating high-saline organic wastewater.

Original languageEnglish
Article number143258
JournalChemosphere
Volume364
DOIs
Publication statusPublished - Sept 2024

Keywords

  • Halotolerant bacteria
  • High salinity
  • Membrane biofouling
  • Membrane bioreactor

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Lin, H., Du, Y., Yu, M., Zhang, W., & Cai, W. (2024). Unveiling the impacts of salts on halotolerant bacteria during filtration: A new perspective on membrane biofouling formation in MBR treating high-saline organic wastewater. Chemosphere, 364, Article 143258. https://doi.org/10.1016/j.chemosphere.2024.143258