Influence of pre-treatment combinations on RO membrane fouling

• Different combinations of pretreatment for RO used in remote area were assessed to reduce organic fouling.
• Two types of waste water were used in the experiments.
• TOC reduction was assessed for each barrier and pretreatment combination.
• The RO performance was assessed based on flux decline till the overall recovery about 70%.
• Ozone + Ceramic membrane + BAC in all combinations gave a best protect to RO membrane.

Pretreatment before reverse osmosis systems in water reuse plants is necessary to prevent rapid fouling. The secondary effluent can at times contain a high suspended solids load with a high proportion of colloidal material, organic compounds and bacteria. Such constituents can cause irreversible fouling of downstream RO systems if not successfully removed during pretreatment. To minimise RO membrane organic fouling, a pretreatment combination including advanced oxidation (ozonation), ceramic MF and biological activated carbon (BAC) was assessed. It was found that fouling formed by the feed wastewater pretreated by the combination of ozonation + ceramic MF and BAC can be easily removed by deionised water flushing, in comparison with MF, BAC, or ozone + MF.