Forward Osmosis and Membrane Distillation desalination process
Thermal desalination is a complicated process to master efficiently and at low cost. In particular in the Gulf region where seawater is particularly concentrated, thermal desalination requires a large amount of heating iterations, thus a large plant and high costs.
DESOLINATION develops an efficient thermal desalination system using several processes:
- A waste heat recovery at tunable temperature
- Innovative membranes for Forward Osmosis
- A tuned draw solution to extract water from seawater
- Coupling of Forward Osmosis and Membrane Distillation
- Extraction of relevant minerals from the rejected brine
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The adaptive coupling will be used to de-risk the coupling process and make sure that all the steps of the heat recovery process are understood before proceeding with the direct coupling of both CSP and desalination.
Smart control systems are thus used in the water storage tank to gather data on temperatures and pressures after each type of cycle and test the most appropriate responses on the heat exchangers and fluids.
After the indirect coupling of CSP and desalination, both processes will be directly linked, removing the smart heat control system and merging the heat exchangers between the power cycle and the draw solution.
The desalination cycle itself is two-fold:
1. Forward osmosis:
Seawater is extracted from the sea, water is driven through the membrane by the draw solution and the remaining minerals (brine) are rejected. During DESOLINATION, brine is treated to revalorise its minerals.
- Membrane distillation:
Using the recovered heat, water is separated from the draw solution and goes through the membrane to be collected as freshwater while the draw solution circles back to the beginning of the loop.
To optimise both processes, the draw solution is tuned to serve several purposes: efficiently attracting water from the sea water, efficiently using the heat recovered from the CSP power cycle and easily being separated from water at the membrane distillation step.