Neighborly reactions
Undergraduates applied chemical reaction engineering principles to model the water reuse systems at the Center for Sustainable Landscapes at Phipps Conservatory and Botanical Gardens. The new collaboration exposes students to the complexity of real-world engineering.
Commonplace processes, like baking bread or purifying water, are made of complex chemical reactions occurring in reactors. Chemical engineering undergraduates learn to model reactions in various types of reactors through a new project in the Chemical Reaction Engineering course. Using the skills they developed in class, students collaborated with Carnegie Mellon University neighbors on their water sustainability processes.
Coty Jen, who teaches the course, envisioned the project to help third- and fourth-year students build lifelong knowledge in chemical engineering by connecting math equations and models to chemical reactors in a real-world context. Jen, associate professor of chemical engineering, and her course assistant, Gabe Mendez-Sanders (ChemE ‘24), spent fall 2024 establishing a collaboration with the Center for Sustainable Landscapes (CSL) at Phipps Conservatory and Botanical Gardens. The partnership produced 12 unique “Reacting with Nature” projects for students to model the CSL water reuse systems as chemical reactors.
The CSL is a “living museum” designed to bring attention to the intersection between built and natural environments. Its building treats all storm and sanitary water captured on-site through two water reuse systems.
The sanitary water reuse system starts with a constructed wetland, where plants absorb some of the pollutants in water from toilets and sinks. From there, the water goes through sand filtration and then ultraviolet (UV) filtration.
The CSL also has a system to collect rainwater from their roofs and from Phipps Conservatory. The rainwater goes through a constructed lagoon as well as UV filtration.
Jen and Mendez-Sanders, a Fifth Year Scholar in the Department of Chemical Engineering, share an interest in showing students environmental applications for chemical engineering to help them see the breadth of the field.
Twelve student teams investigated specific stages of the CSL water reuse systems. Before getting started, the class learned about challenges that the CSL faces implementing and continuously operating the system in the real world. “Many designs are built from gut instinct without detailed models or experimental data,” says Jen.
Elyse Wilkerson (far left) and her team present their analysis of using a waterfall to prevent harmful algal blooms in the lagoon.
The teams modeled parts of the water reuse systems to attempt to explain why problems are happening and to propose potential solutions. Their analyses are based on chemical reaction engineering principles. For example, Elyse Wilkerson’s team was tasked with using a waterfall to prevent the harmful algal blooms that form in the lagoon as nitrogen and phosphorus accumulate.
Several groups also explored the potential to scale up the CSL water reuse systems for larger institutions. Maerah Mahmood’s team worked on rescaling the stormwater lagoon for Carnegie Mellon University and then mitigating algal blooms at the larger scale.
When deciding which type of reactor to model, each team considered their input and output streams. “We weighed the pros and cons of the reactor types we discussed in class, to see how each would fit the system,” says Wilkerson. “What assumptions do we have to make in the real world about things like volume and mixing? What are the costs of those assumptions?”
Maerah Mahmood (center) and her team present their analysis of rescaling the stormwater lagoon.
In developing the project, Mendez-Sanders wanted to expose students to the complexity of real-world engineering. Touring the CSL reminded him of challenges he encountered during industry internships. “The original design is super awesome, and a lot of it isn’t currently operating the way they expected or hoped. That is what real engineering is like,” he says. Mendez-Sanders designed the project to help students learn how to navigate unexpected challenges and still get something functional.
“From when we started brainstorming ideas to our conclusion, our path had to change a lot,” says Mahmood. “Some things are infeasible in a real-life setting. With only a conceptual understanding, we might not have reached the same conclusion.”
The project culminated with a poster session at Phipps Conservatory’s Botany Hall, where students presented their model analysis to members of the CSL and the public. Jen and Mendez-Sanders wanted to give students the opportunity to present their technical work to people with different expertise.
“I am really impressed with the novel and innovative solutions that the groups have proposed to real problems,” says Mendez-Sanders.
The Department of Chemical Engineering would like to acknowledge Phipps Conservatory and the Center for Sustainable Landscapes for giving staff time and the use of Botany Hall for the poster session.
The poster session was partially supported by the PPG Chemical Engineering Undergraduate Professional Development Fund. The Department of Chemical Engineering would like to acknowledge the financial assistance from the PPG foundation with gratitude.