Greenhouse Canada

Low-cost water purification technique

May 15, 2018  By Greenhouse Canada

Huaxiu Chen

Researchers at the University of Buffalo have come up with a water purification technique for areas with limited access to clean water – and they’re looking to apply the same technology to greenhouses.

Initially designed as a low-cost solution to clean water, the technology used carbon-dipped paper propped into an upside-down “V” shape. The two bottom ends of the paper soak up the water, while the dark carbon coating absorbs the sun’s energy to heat up and evaporate the water. Any salt, bacteria or dirt is left behind, and the clean water vapour is cooled and collected.
According to lead researcher and associate professor of electrical engineering at the University of Buffalo, Qiaoqiang Gan, some of the solar energy is lost as waste heat during a normal evaporation process. But their system changes all of that.

“Our system has a way of drawing heat in from the surrounding environment, allowing us to achieve near-perfect efficiency,” says Gan.


How? Together with Dr. Haomin Song, PhD candidate Youhai Liu and other colleagues, Gan and his research team found that by keeping the purification system at a lower temperature than its surroundings, they could get higher amounts of vapour generated. The heat from the surrounding environment adds to the vapourization process, replacing the solar energy lost through waste heat. The sloping “V” shape helps avoid direct contact with the sun, helping cool the system.

Gan, Song and others have since launched Sunny Clean Water, a start-up company that is looking to incorporate this new technology into a solar still, improving the efficiency of this age-old device.

“With a solar still the size of a mini fridge, we estimate that we can generate 10 to 20 liters of clean water every single day,” says Song.

For every square meter illuminated by the sun, the team has been able to evaporate 2.2 L of water per hour.

The company is now looking to test this technology in greenhouse environments, where recycling water and moisture could prove both useful and cost-effective. As the patent is currently under way, Gan could not comment on technical specifics at this point.

He is, however, looking to collaborate with greenhouse operators in Ontario. Interested? Contact


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