White Paper: Reverse Osmosis Membranes For Wastewater Reclamation

Wastewater reclamation has become a viable alternative to supplement water supplies in water-short areas. In particular, membrane treatment has played an important role in purifying the water cost-effectively. Reverse osmosis membranes have been shown to significantly reduce total dissolved solids, heavy metals, organic pollutants, viruses, bacteria, and other dissolved contaminants. Experience from commercial membrane wastewater treatment plants has demonstrated that there are key design parameters which must be followed to prevent rapid membrane fouling, and thus reduce high system maintenance costs and significant downtime. In particular, current best practices include the use of ultrafiltration or microfiltraiton membranes to remove colloidal debris, maintain a chloramine residual to prevent biogrowth, select proper antiscalant chemicals limit RO recovery rates to prevent membrane scaling, and utilize membranes which minimize organic fouling. Select conventional polyamide and low fouling membranes have been used successfully at plants such as the West Basin Wastewater treatment plant in California or the Bedok and Kranji plants in Singapore. These large-scale plants provide the basis for even larger plants, and greater contribution to the water supply in needy regions.