Image via MIT
Water, a natural resource often taken for granted is barely in reach for two billion people around the world. Startlingly, UNICEF estimates that half the world’s population will struggle with this problem in just three years.
One way to generate supply is by drawing from oceans, which cover 70% of Earth. Clean drinking water can be obtained by filtering seawater in a process called desalination. As reported by the , water-scarce communities in the Middle East and California turn to this approach.
On paper, desalination sounds ideal; after all, there seems to be more than enough water to go around. However, desalination systems require regular maintenance due to a buildup of salt from the seawater—and the equipment gets damaged, or fouled, if its parts aren’t cleaned or replaced frequently. Naturally, this upkeep demands significant costs and resources.
But desalination doesn’t have to be expensive or labor-intensive, as a team of researchers from MIT and Shanghai Jiao Tong University has found. They have devised an affordable solar-powered instrument that practically eliminates salt buildup, ensuring that maintenance or replacements are kept at a minimum.
The best part? The equipment is built with cheap, almost everyday materials, driving its cost down to only US$4. The accessibility of its materials also means that households all over the world can potentially enjoy abundant drinking water.
It’s the wick in typical desalination devices that’s prone to salt buildup—so the scientists removed it altogether. In its place is a floating, multi-layered model that separates salt from water.
As detailed in the Nature Communications scientific journal, the equipment relies on a natural phenomenon called convection, where hot fluids rise to the top and cool fluids sink.
The device tested on deionized water (left) VS saltwater (right). The water has been colored in food dye to illustrate flow. Image via MIT
At the base is a layer with tiny holes that draws water to the top, which features a dark, sunlight-absorbing material. The sun warms, and evaporates, the water at the surface, which is then collected on a condensed surface. The leftover salt flows to the bottom via the holes.
The scientists observed no fouling of the apparatus after using it for a week.
For now, the idea remains a proof of concept, but the team foresees it evolving into a scalable solution to bring pure freshwater to the masses, particularly in areas where water isn’t as accessible.
“I think a real opportunity is the developing world,” explains Evelyn Wang, an MIT mechanical engineer and the study’s co-author. “I think that is where there’s the most probable impact near-term, because of the simplicity of the design.”
Peng Wang, a professor at Saudi Arabia’s King Abdullah University of Science and Technology who was not involved in the project, lauds the effort. “This is a new strategy toward solving the salt accumulation problem in solar evaporation. This elegant design will inspire new innovations in the design of advanced solar evaporators,“ Wang describes in MIT’s news release.
“The strategy is very promising due to its high energy efficiency, operation durability, and low cost, which contributes to low-cost and passive water desalination to produce fresh water from various source water with high salinity.”
[via
http://www.designtaxi.com/news/417787/4-Desalination-Innovation-Could-Bring-Drinking-Water-To-Scarce-Communities/
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