Modifying thin-film composite forward osmosis membranes using various SiO₂ nanoparticles for aquaculture wastewater...

This paper describes the fabrication, modification, and evaluation of the performance of thin-film composite (TFC) forward osmosis (FO) membranes for lab-scale aquaculture wastewater recovery using various fumed silica (SiO₂) nanoparticles. The active polyamide (PA) layers of these membranes were novelly modified using different types of pretreated SiO₂ nanoparticles [virgin SiO₂, dried SiO₂, and 3-aminopropyltriethoxysilane (APTES)-modified SiO₂] and concentrations (0.05, 0,1, 0,2, and 0.4 wt%) to improve the membrane hydrophilicity with minimum particle agglomeration. Results show that the APTES-SiO₂ modified membrane had the highest water flux and selectivity, followed by the dried-SiO₂ modified membrane. The APTES coupling agent notably reduced the SiO₂ aggregation on the membrane surface and improved membrane hydrophilicity. Consequently, high permeate flux and an acceptable reverse solute flux were observed. The optimal SiO₂ concentration for PA modification was 0.1 wt% for all the nanoparticle types. The virgin and APTES-SiO₂ modified membranes were used for aquaculture wastewater recovery. The water recovery rate reached 47% in 84 h when using the APTES-SiO₂ modified membrane, while it reached only 26% in 108 h when using the virgin membrane. With a suitable design of the filtration apparatus and choice of draw solution (DS), the prepared novel TFC-FO membrane containing APTES-modified SiO₂ can be used for recycling aquaculture wastewater into the DS, which can then be reused for other purposes.