US Patent 10258926 Hybridization of humidification-dehumidification and pressure-retarded osmosis

A carrier gas and a combined feed liquid are directed through a humidifier, where water vaporizes from the combined feed liquid into the carrier gas, and through a dehumidifier, where the combined feed liquid cools the carrier gas to condense water from the carrier gas. At least a portion of the concentrated brine stream from the humidifier is directed through a pressure-retarded osmosis unit, while an initial feed solution is directed, in counter-flow, through the osmosis unit. Water from the initial feed solution flows through a membrane in the osmosis chamber into the concentrated brine stream to dilute and increase the volumetric flow rate of the brine stream. The diluted brine stream is extracted from the osmosis chamber and depressurized to produce power, while the concentrated initial feed solution is combined with the depressurized, diluted brine stream to form the combined feed liquid.