CHARACTERISTICS AND COSTS OF MF AND UF PLANTS

A questionnaire was sent to membrane filtration plants worldwide regar ding their capacities, operation, water quality, and costs. The total plant capacity of all utilities responding was 49 mgd (185,500 m(3)/d) . About 90 percent of the existing plants have design capacity <1 mgd (<3,800 m(3)/d). The largest plant is a 15-mgd (57,00-m(3)/d) ultrafil tration plant currently being commissioned in France. Source waters fo r the plants included both groundwater (35 percent) and surface water (65 percent) and were not necessarily limited to high-quality waters. Although influent total coliform concentrations ranged from 1 to >1,00 0/100 mL, none of the plants reported the presence of coliforms in the ir permeate. The current treatment unit cost for membrane filtration r anges from <$0.50/1,000 gal (<$0.13/m(3)) for plant capacities >5 mgd (>19,000 m(3)/d) to as high as $2.50/1,000 gal ($0.66/m(3)) for plant capacities of 0.01 mgd (38 m(3)/d). Capital and operation and maintena nce costs of membrane filtration are expected to continue to decline.