July 27, 2021
CEE Capstone: Aquaponics for Center of Life
“When I found out that we were doing this project for a community in Pittsburgh, I was ecstatic. The purpose behind our work really fueled us,” CEE student Valentina Ortiz de Zárate (BS '21) says of this year’s senior design project, which involved partnering with Center of Life, an organization dedicated to revitalizing the Hazelwood neighborhood of Pittsburgh.
For the fall senior capstone course, CEE students were tasked with designing a prototype of an aquaponics food production system and an energy-efficient facility to house it. “In an aquaponics system, fish and plants work together,” explains Joseph Iacobellis (BS '21). “As the fish live and excrete waste, the plants grow by absorbing nutrients from that waste.” Center of Life hopes to use these prototypes to create a facility to host educational events for schools and community members as well as produce food they could sell at a farmer’s market for revenue.
Each group working on the senior project focused on different subsystems of the facility, including the aquaponics system, structural design, and electrical design. Additionally, an automation group designed a plan to monitor factors like water quality and temperature and inform facility managers about the plant and fish health.
“Including sensing and automation is exciting because that is the future of infrastructure,” says Sarah Christian, the course instructor. “Students were able to see how those information systems interact with the other systems they’re dealing with in a way that requires domain knowledge in civil and environmental engineering as well as an understanding of computing.”
Unifying every group’s design, of course, required much coordination and collaboration. “I was someone who thought to build on the fly and plan as we go, but that wouldn't have been possible,” says Iacobellis. “There were so many steps to be taken into account and communications that needed to happen to make sure that the things we were doing would work correctly with the other groups.”
After the students submitted their designs in the fall, another group of seniors continued the work in the spring, creating a functioning aquaponics prototype with a fish tank and two plant growing areas. To clean the waste from the fish, the dirty water is moved first to a separator tank and then a biofilter, which transforms the waste into fertilizer. After the plants use the fertilizer as nourishment, the clean water is returned to the fish tank to restart the cycle.
At first, the prototype featured only Deep Water Culture (DWC) beds, where rafts of leafy greens float in a tank of nutrient-rich water. After selecting this growing method for its ease of use, the students realized that the client preferred to prioritize maximizing production. As a result, they added a second growing method: Nutrient Film Technique (NFT) channels, in which nutrient-rich water travels through horizontal PVC pipes. As plants grow on and through the pipes, their roots are exposed to the water inside.
“What's cool about NFT channels is you can layer them. We have one layer, but that could be stacked vertically to maximize vertical space,” explains Ortiz de Zárate. “Having to think about a client and incorporate their feedback guided our design to a more innovative direction.”
The design also reflects the organization’s educational goals by allowing visitors to walk around each area, learning about the process in a logical order.
For Ortiz de Zárate, this work was an opportunity to not only explore her environmental engineering interests but also areas outside her focus. “The project was a great combination of the disciplines within Civil Engineering,” she says. “As I worked on the aquaponics system and water flow calculations, the structural civil engineers were designing and constructing the support systems for the DWC bed. We had to work very closely, so I learned a lot about what they were doing and they learned a lot about my expertise.”
Beyond the technical knowledge gained, the students also walked away with stronger project management and communication skills and a readiness to handle the unknown and unexpected. “Nobody that we were directly working with had all the information,” reflects Iacobellis. “We had to reach out to our client and to suppliers and contractors for quotes and advice. It was a lot of learning on the fly, a lot of improvisation and a lot of communication. It helped myself and other students go outside our comfort zone, and everyone valued that.”