Microalgal biofouling formation on tubular cellulose-ester membranes during dewatering by forward osmosis

Abstract

This work assesses the biofouling formation of a microalgal consortium, cultivated in wastewater, on dialysis tubular membranes with no supporting layer, in both batch and continuous FO dewatering modes. The biological adhesion strength was compared with the predictions from the Baier and Vogler biocompatibility theories, employing critical surface tension (${\gamma }_c$) and water adhesion tension (τ⁰), respectively, as measurable parameters of surface wettability. The results indicate that most of the tested membranes presented amphiphilic surface characteristics (τ⁰=22 to 45 mJ.m⁻², θ_W ≈ 65˚) with a minimal biological adhesion tendency, which is compatible with the Vogler criteria. However, the membrane exposed the longest time to the microalgal culture presented more hydrophobic characteristics and poor wettability. The existing thermodynamic models succeeded in predicting cell-cell and cell-surface interactions as a competitive phenomenon. Nevertheless, the XDLVO model was used to determine changes in the cell-to-surface attraction dynamics. This assessment of microalgal foulant-membrane interfacial interactions helps to enhance understanding of the fouling mechanisms present on a novel FO membrane surface.

Keywords:

• Microalgal biofouling
• forward osmosis
• thermodynamic approach
• XDLVO theory

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that might influence the work reported in this paper.

Additional information

Funding

This research was supported by the UAL18-BIO-A016-B1 grant from Feder-Andalucía 2014-2020, the biofouling project RTI2018-101891-B-100, and the Biotechnology of Marine Microalgal Research group, BIO-173. The lead author received support from an Iranian government scholarship.