COST MODEL FOR LOW-PRESSURE MEMBRANE FILTRATION

A model for capital and operating costs of low-pressure membrane filtration is presented. The model is used to explore the impact of variables describing system operation and membrane characteristics on treatment costs as well as to compare the cost of treating raw waters of different qualities using nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF). The cost of UF or MF to remove particles from raw waters of moderate to high turbidity and concentrations of dissolved organic carbon (DOC) is calculated to be approximately twice that required to treat low-turbidity streams or ground waters. At small design capacities (2,000 m3/hr), UF and MF are calculated to be competitive or less expensive processes for liquid-solid separation in potable water treatment when compared with conventional filtration. MF and UF costs calculated tor small facilities (almost-equal-to 20 m3/hr) treating low-turbidity waters are comparable. For larger design capacities, UF may be less costly than MF. Treatment applications requiring significant removal of DOC and/or divalent ions may warrant the higher costs calculated for NF.