A new technology combining distillation with membrane filtration uses waste heat from industries to turn seawater into drinking water
Albert Jansen, membrane expert at the Netherland’s Organization for Applied Scientific Research (TNO), talks about his new seawater desalinisation technology, designed to meet the increasing demand for clean drinking water. The project is a part of the AQUAFIT4USE scheme, funded by EU.
How does the technology compare to other desalination technologies?
The old way of doing desalination is to distillate the saltwater. Nowadays, a technology called reversed osmosis is more widely used. This involves applying pressure to the saltwater and forcing it through a membrane that leaves behind the salt. Our technology, called Memstill, uses a process called membrane distillation, which is a mix between these two older technologies.
What brought you to develop this technology?
The conventional technologies for desalination require a lot of energy. This means that it’s still rather expensive to turn seawater into drinking water. So our main drive was to make a cheaper and more sustainable desalination process.
What makes this technology more sustainable than others?
The only energy source required for the process is waste heat; the heat that’s automatically generated by many industries during their production. We use temperature differences between the membranes and a condensor to evaporate water through membranes that leaves behind saltier water. The process only requires temperatures below 90 degrees. This makes it possible to use waste heat or solar panels for the desalination process.
What are the challenges encountered?
The big challenge is for the equipment suppliers to produce high quality membrane modules at low costs. The problem right now is that most membrane modules are better when we build them by hand than through industrial methods. Membranes used in the process of membrane distillation are fragile because they lack a support layer and have a large surface area. This makes them less suited for industrial production. The development of this production technology is ongoing and we are now testing the first promising results.
What is the next step in the research?
We finished testing the desalination process in our pilot plants in Singapore and Holland with very good results. Our calculations show that our technology is much cheaper to use than other state of the art technologies. Its price ranges between 30 to 140 eurocents per cubic meter desalinated drinking water, whereas other desalination technologies report costs ranging between 50 cents and 2 Euros. But so far all our testing is short term and I think the technology needs to prove itself for several years before we’ll see it in large scale drinking water production.
Now, we are also testing how our technology can be applied for the removal of wastewater from industries; a technique referred to as dewatering. The idea is that industries can turn wastewater into high-quality water at low temperatures. But we still need to do more testing and the challenge is, that different industries have different types of wastewater.
*) Photo credit by TNO
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