Effect of size fractioned alginate-based transparent exopolymer particles on initial bacterial adhesion of forward osmosis membrane support layer

In the forward osmosis (FO) process, biofouling is well pronounced on the active side where wastewater and seawater are used as feed and draw solution, respectively. However, the biofouling tendencies within the support layer are not clear. Therefore, the objective of this study was to investigate the effect of TEP pre-conditioning on hydophobicity and initial bacterial attachment of FO membrane support layer. Two structurally distinct FO membranes from different manufacturers were pre­conditioned by soaking in artificial sea water filtrates containing size fractioned TEP. The conditioning solution pre-treated with a 0.4μm pore size filter, contributed to the highest bacterial adhesion rates during bacterial attachment testing in both steady state and cross-flow mode in a lab-scale FO system for both membrane types. CTA-ES support exhibited higher numbers of adhered bacteria when compared to PA-TFC support in a steady state. Conversely, in cross-flow lab-scale testing, a negative impact of fouling on PA-TFC was more apparent than the CTA-ES membrane. This was attributed to the higher porosity and surface roughness of the PA-TFC membrane. Overall, our findings reinforce the potential impact of hydrodynamics conditions and membrane properties on the fouling behavior of FO membrane support layer.