The Pressure Retarded Osmosis (PRO) membrane is the key factor affecting the PRO performance (both water flux and power density). However, the most apparent drawback of the current membranes used for PRO is severe membrane deformation at high applied pressures which enhance the internal concentration polarization (ICP) and hence decrease the water flux and power density under PRO operation.
The optimal PRO membrane should incorporate the characteristics of both RO membranes and FO membranes. In this invention, a PRO membrane was fabricated based on the above principle. A hydrophilic tricot mesh fabric with strong mechanical strength and high porosity was embedded into the middle substrate layer to support the whole membrane. A selective thin rejection layer was formed on the top of the middle substrate layer.
To date, there is no commercial membrane specially designed for PRO application. The reported membranes used for PRO testing either have low performance or lack mechanical stability. This invention developed a robust thin film composite (TFC) membrane with reinforced mechanical strength and high power density specifically for PRO application.
The reinforced PRO membranes can be competitively used for producing osmotic power in PRO processes when operated under a variety of conditions especially at high applied pressures. These include the following,
• Osmotic power plant for producing electricity.
• Desalination industry for diluting the seawater and waste brine as well as harvesting the osmotic power from the waste brine.
• Hybrid single or dual PRO and RO system for reduced energy consumption and easy disposal of brine to the ocean through simple mixing and without capital intensive brine dispersal outfalls.