UC Students Engineer Safer Irrigation Water with Solar Power

Access to safe, high-quality irrigation water can make or break a farmer’s livelihood. But in certain rural areas, like the remote countryside of Colombia, farmers often have access only to brackish water, or water with a higher salinity than freshwater. Left untreated, this brackish water is too salty to use on crops or for cattle. 

Colombian farmers, therefore, must determine how to treat their water before they can use it for irrigation. This usually requires some form of energy. But in Colombia, where farmers must operate independently from an unreliable power grid, this is easier said than done.

So, how can these farmers use the water they have?

One senior design team at the University of Cincinnati set out to answer this question. The team, which consisted of three mechanical engineering students and three environmental engineering students in UC's College of Engineering and Applied Science, worked with OMID, a nonprofit organization that finds renewable energy solutions for rural farming communities.

“Being part of something that can have a global impact was a big point for all of us,” UC mechanical engineering graduate Zach Jones said.

Brackish water is not just a problem in Colombia; any area far enough from a water source may encounter saltier-than-usual water. As glaciers or snow on mountaintops melt, the water runs down a mountain as a stream or river, picking up mineral-rich sediment along the way. Additionally, farmers and other residents can use and recycle this water, increasing its salinity. Rural farmers at lower elevations may get water that has been used several times upstream. This overuse of water, along with poor farming practices and the great distance from a water’s source, can lead to highly saline brackish water.

Integrating three projects from last year, the team designed and modeled a prototype rooted in electro-dialysis and powered by solar energy. They chose this power source because of the remote nature of the farms. Without a reliable power grid, farms must generate their own power.

Electro-dialysis is also a great alternative to reverse osmosis, a common desalination technique, explained Adam Chalasinski (environmental engineering ’18). Reverse osmosis operates under similar principles as electro-dialysis but requires much more energy, which is unrealistic in rural Colombia.

In the team’s case, electro-dialysis operates using two parallel metal plates placed in a water tank. Once the sun rises, the solar panels provide power to the plates, releasing a measured electric charge.

“When salts are dissolved, they break into positive and negative ions,” said Jason Lorah (mechanical engineering ’18). “When you charge a plate, these different ions go in opposite directions. You’re left with two streams in your tank with a high density of salts and one middle stream with fresh water.”

In some tests, the team removed 99 percent of the salt from the water. 

Additionally, the team linked the tank and special sensors to a software application that users can access from a phone or computer. Since different crops require different water types, farmers can determine how much salt is in the water and adjust the tanks according to their needs.

The model the team created is also completely open source, meaning anyone can freely access the design, technology or software of the system and use it to solve similar water problems.

OMID has a partnership with an agriculture school in Colombia, which plans to use this prototype as the model for a full-scale design. Another organization will then manufacture this full-scale model for distribution. The team estimates that a full-scale tank that treats 2,000 gallons of water per day (a standard tank size in the region) would cost $17,000 to $18,000.

The team hopes its work establishes the foundation for safer irrigation water in the future. This means higher yields and increased productivity for farmers in rural areas. Using innovation and collaboration, the team has flushed unsafe brackish water down the drain.  

The senior design team consisted of Lisa Barkalow, Adam Chalasinski, Zach Jones, Jason Lorah, Zach Spangler and Alex Watzek.