In a project managed by the National Energy Technology Laboratory (NETL), GE Global Research has advanced a method to lower the energy requirement and cut the cost of recovering usable water from high-salinity brines. The new technology offers a way to turn a potential waste product into a usable source of water and minerals.

Water and energy are surprisingly interconnected: much water is needed to generate electricity, and much energy is needed to purify water. The lowest energy method of water purification is typically a membrane process, such as reverse osmosis; however, some wastewaters are not good candidates for this because of very high salt concentrations. Reverse osmosis also leaves behind a brine with very high salinity that must be disposed of properly.

In this project, GE aimed to reduce the amount of energy needed to recover water and salt from high-salinity brines. Rather than evaporating and condensing water, which is energy intensive, researchers sprayed brine in a stream of a cold refrigerant, freezing the brine droplets. Proper control of the freeze conditions allowed separation of ice crystals from salt crystals.

Examples of wastewaters that could be treated with this new freeze process are produced water from oil and gas extraction, brines from deep saline formations that may be used for CO2 storage, and power plant waste streams that have been reused and concentrated.

The trend in wastewater treatment is toward “zero liquid discharge,” in which all wastewater is purified and recycled, leaving zero discharge at the end of the treatment cycle. This is one method to meet this goal. The GE process has demonstrated 100 percent water recovery and a 58 percent reduction in the cost of water treatment compared to a thermal crystallizer.