White Papers
Three Pressure Retarded Osmosis PRO Processes
Pressure retarded osmosis (PRO) can be implemented on a number of water types, using different technologies and achieving various power outcomes. This paper presents the three most practical options.
Boris Liberman, VP & CTO Membrane Technologies
The paper describes three options in detail:
Option 1 – Seawater with river water, driving force 25 bar, power output 5-10 watt/m2
Option 2 – SWRO brine with wastewater, driving force 50 bar, power output 10-20 watt/m2
Option 3 – Dead Sea or salt lake with river water, driving force 250 bar, power output 50-100 watt/m2
Each of the above options requires a different PRO technology.
Option 1 necessitates movement of huge water volumes with extremely low power losses. All water movement must be at seawater level. The pressure exchanger consumes 15 times less power than it does in RO technology. Pretreatment CAPEX and OPEX expenses are considerably less than those currently implemented by RO technology, while water quality has to be as good as that required from RO.
Option 2 is the most economical and ready to use. This option uses already filtrated and pressurized brine from an SWRO plant. The main obstacle to the implementation of this option is finding a wastewater source with no cost.
Option 3 implements natural exotic resources such as Dead Sea water with extremely high osmotic pressures. The PRO technology in this option requires membranes and pressure exchangers that are able to operate at extremely high pressures.
