Combination of coagulation and ion exchange for the reduction of UF fouling properties of a high DOC content surface water

The treatment of a high DOC content surface water (about 6 mg DOC/L) using anion exchange resins (MIEX® resin from Orica or IRA958® resin from Rohm and Haas) can remove up to 80% of DOC in less than 45 min. The combination of coagulation prior to or after resin treatment only slightly improves the removal of DOC (0.2–0.3 mg/L) but eliminates the high MW organic compounds (MW >20 kDa) attributed to biopolymers (proteins and polysaccharides) that were not removed using anion exchange resins alone and that were found to be responsible for reversible fouling of UF membranes (YM 100 UF membrane from Millipore with MW cut-off of 100 kDa). The combination of treatments then significantly improves the permeability of the UF membrane. Also, the combination of both treatments allows a reduction of the coagulant doses by a factor of 6 with no impact on the DOC removal and the filterability of produced waters.