Effects of feed solution chemistry on membrane scaling in fertilizer-drawn forward osmosis process for sustainable agricultural reuse

Scaling formation on the forward osmosis (FO) membrane surface is a critical problem in fertilizer-drawn forward osmosis (FDFO). In this study, the effect of feed solution chemistry on scaling formation in the FDFO process was investigated. The results revealed that the flux decline ratio (FDR) increased with the pH of the feed solution owing to the acceleration of reverse salt flux (RSF) diffusion. FDR decreased as the temperature of the feed solution increased. Higher temperatures in the feed solution hinder membrane scaling by interrupting the RSF from the draw to the feed solution. Calcium has higher reactivity than magnesium, and it has a higher potential for forming scales on the membrane surface than magnesium in the FDFO process. The flux was not fully recovered by physical cleaning, but 87 % of the water flux was recovered using chemical cleaning using an acid solution (HCl). This study provides information on membrane scaling in the FDFO process for wastewater treatment applications.