CEAS Students Engineer Safer Irrigation Water with Solar Power

By:    Brandon Pytel
Date: May 8, 2018

Six CEAS students used their senior capstone project to design a solar-powered tank that treats brackish water for agricultural irrigation purposes.

Capstone team stands with prototype.

The team designed and modeled a fully functional prototype rooted in electro-dialysis and powered by solar energy.

model of desalination tanks on rural farm.

OMID plans to take the team's design to create a full-scale model.

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 Columbia, farmers usually only have access 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.

Columbian 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 Columbia, 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 (UC) set out to answer this question. The team, which consisted of three mechanical engineering students and three environmental engineering students in the College of Engineering and Applied Science (CEAS), worked with OMID, a non-profit 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,” said Zach Jones (mechanical engineering ’18).

Brackish water is not just a problem in Columbia; any area far enough from a water source may encounter saltier-than-usual water. As glaciers or snow on mountain tops 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 over upstream. This overuse of water, along with poor farming practices and sheer distance from a water’s source, can lead to highly saline brackish water.

Integrating three separate design projects from last year, the team designed and modeled a fully functional 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, these 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 Columbia.

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.

diagram of electrodialysis concept

Electro-dialysis separates the positive and negative ions in salt, desalinating brackish water.

“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, less saline 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 Columbia, 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 their 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.