At the Coal Face: Preventing Iron & Manganese Fouling of Brackish Water Reverse Osmosis Membranes

A containerized WTP using inside-out ultrafiltration as pretreatment to brackish water RO membranes with blending was built for treating mine influenced water prior to discharge to a local waterway. It was found that water quality changed and caused rapid fouling of the membranes due to oxidized iron and manganese that even very frequent CIPs could not maintain membrane performance. Trials were conducted with alkali addition to precipitate dissolved metals before UF, and acidification to retain dissolved metals in solution. The final solution usses citric acid to reduce pH below 4.5 and te plant now achieves original recoveries with acceptable cleaning frequencies.