Making Water shouldn't Waste Water
The Next Generation of Desalination can handle scaling while producing zero liquid discharge.
The objective of the Trevi forward osmosis process is to desalinate water at lower pressure and lower energy than a reverse osmosis system. In order to achieve a low energy system we take advantage of a concentration gradient to pull water across a selectively permeable membrane and ‘waste heat’ to separate the draw solution from the water. The Trevi FO System will perform optimally when used in conjunction with thermal energy sources such as solar ponds or solar concentrating systems because the technology development is focused on a system that is thermally driven rather than electrical.
Research
& Development
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Benefits
Green Chemistry
Draw solution lifetime is to be determined but is expected to be greater than 2 years. The draw solution is biodegradable and non-toxic in aquatic environments.
Zero Liquid Discharge
Affordable Water
Trevi FO system operates under very low pressure <60 psi, thereby reducing membrane fouling and the need for expensive piping.
The brine stream generated may be concentrated to either very low or very high recovery rates without a noticeable change in electrical energy consumption.
Sustainable Design
The process has the ability to desalinate ocean water at 1/8th the electrical energy of current RO systems (0.5 kWh/m3
Systems Process
Forward osmosis (FO) is an osmotic process that uses a semi-permeable membrane to effect separation of water from dissolved solutes.The driving force for this separation is an osmotic pressure gradient between a solution of high concentration, often referred to as a “draw” and a solution of lower concentration, referred to as the “feed”.
The seawater is pretreated by an ultrafiltration process, and pumped to the feed side of the FO membrane.
The Brine exits the FO membrane and is discharged through a pipe to a drain at atmospheric pressure.
Draw solution, diluted by the passage of water across the FO membrane, is heated by the heat exchangers prior to separation
The water is separated from the draw solution by a coalescer.
The osmotic pressure gradient is used to induce a net flow of water through the membrane into the draw, thus effectively concentrating the feed.
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The water is pumped to the polishing nanofilter and then to a holding tank for remineralization.
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Intellectual Property
Trevi currently holds a patent filed in 21 countries, as well as 5 provisional patents for this forward osmosis process.
Trevi’s contribution to the advancement of forward osmosis rests in the development of thermally responsive organic draw solution(s) and the energy recovery process associated with the system. Trevi is working closely with several membrane manufacturers to optimize the membrane design to account for the unique properties of the Trevi draw solution and may develop its own membrane to expedite the roll-out of the technology.