Organic fouling in pressure retarded osmosis: Experiments, mechanisms and implications

► Organic fouling in pressure retarded osmosis (PRO) was systematically investigated. ► PRO fouling was more severe at higher water flux (Jv). ► Reverse solute diffusion (Js) played an important role in enhancing PRO fouling. ► PRO fouling was more severe at increased draw solution concentration due to higher Jv and Js. ► Increased pressure affected PRO fouling by the competing effects of decreased Jv and increased Js.