Pretreatment Review for NF and LPRO Membranes: Literature Review and Case Studies

Selection of an appropriate pretreatment process for a nanofiltration (NF) or low-pressure reverse osmosis (LPRO) system is critical to optimizing recovery, water quality, and clean-in-place (CIP) requirements. Key pretreatment considerations include whether or not to remove dissolved Fe and Mn ahead of NF or LPRO, whether biofouling control is needed, the extent of filtration required, chemical dosing, and other factors. Common pretreatment processes include antiscalant addition, pH reduction, granular media filtration, membrane filtration, and preoxidation. This presentation will cover a brief literature review of current pretreatment strategies and case studies from a variety of utilities employing various approaches based on their source water characteristics.