title: Experimental results from RO-PRO: a next generation system for low-energy desalination.
abstract: A pilot system was designed and constructed to evaluate reverse osmosis (RO) energy reduction that can be achieved using pressure-retarded osmosis (PRO). The RO-PRO experimental system is the first known system to utilize energy from a volume of water transferred from atmospheric pressure to elevated pressure across a semipermeable membrane to prepressurize RO feedwater. In other words, the system demonstrated that pressure could be exchanged between PRO and RO subsystems. Additionally, the first experimental power density data for a RO-PRO system is now available. Average experimental power densities for the RO-PRO system ranged from 1.1 to 2.3 W/m2. This is higher than previous river-to-sea PRO pilot systems (1.5 W/m2) and closer to the goal of 5 W/m2 that would make PRO an economically feasible technology. Furthermore, isolated PRO system testing was performed to evaluate PRO element performance with higher cross-flow velocities and power densities exceeding 8 W/m2 were achieved with a 28 g/L NaCl draw solution. From this empirical data, inferences for future system performance can be drawn that indicate future RO-PRO systems may reduce the specific energy requirements for desalination by ∼1 kWh/m3.
authors.affiliation: Environmental Resources Engineering Department, Humboldt State University , Arcata, California 95521, United States.
authors.forename: Andrea
authors.initials: A
authors.lastname: Achilli
authors.forename: Jeri L
authors.initials: JL
authors.lastname: Prante
authors.forename: Nathan T
authors.initials: NT
authors.lastname: Hancock
authors.forename: Eric B
authors.initials: EB
authors.lastname: Maxwell
authors.forename: Amy E
authors.initials: AE
authors.lastname: Childress
mesh_terms: D008567:Membranes, Artificial; D009994:Osmolar Concentration; D009995:Osmosis; D010865:Pilot Projects; D011312:Pressure; D054712:Salinity; D012965:Sodium Chloride / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D008567:Membranes, Artificial; D012965:Sodium Chloride