Role of pressure retarded osmosis (PRO) in the mega ton water project
AbstractReverse osmosis (RO) membranes have been widely applied to seawater desalination and wastewater reclamation, and many large RO plants >100,000 m3/d) have been constructed since 2000. Energy efficiency is indispensable for large plants, especially for future mega ton scale seawater reverse osmosis (SWRO) plant (1,000,000 m3/d) In order to reduce energy demand in RO operation, high efficient low pressure RO membrane, energy recovery device (ERD) and pressure retarded osmosis (PRO) which would recover power from salinity gradient between freshwater and concentrated brine were studied in the "Mega ton Water System" project. A PRO hollow fiber membrane module was newly developed, and a practical continuous operation has been examined at a prototype plant for one year. The maximum 13.5 W/m2 of membrane power density using 10 inch module was established at our prototype PRO plant. As the results of the plant cost estimation and the financial impacts on the energy saving operation at the mega ton scale.