Removal of disinfection byproducts in forward osmosis for wastewater recycling

Forward osmosis (FO) is an emerging membrane technology for wastewater recycling. However, its performance in removing disinfection byproducts (DBPs), a critical aspect of wastewater recycling, has not been investigated. This study systematically investigated the rejection of sixteen neutral DBP that are relevant to wastewater recycling in two commercial FO membranes (Aquaporin and CTA). Clean Aquaporin membrane displayed higher rejection for all DBPs than clean CTA membrane. For N-nitrosodimethylamine (NDMA) and haloacetonitriles (HANs), the most prevalent and toxic DBPs in wastewater recycling, the rejection by Aquaporin was 31% and 48-76%, respectively. The rejection of DBPs in FO positively correlated with their size across different DBP groups but did not correlate with their hydrophobicity. Organic fouling by alginate and bovine serum albumin (BSA) decreased the rejection and transmembrane fluxes of most DBPs. The DBP transport and the influence of fouling were discussed using a solution-diffusion model incorporating size exclusion, the surface interaction between the membrane and DBPs, and DBP diffusion within the membrane. Lastly, the rejection of NDMA and HANs in FO membranes determined in this study was compared with that in reverse osmosis (RO) membranes reported in the literature.