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Development of a Low-Cost Constructed Wetlands Experiment

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Conference

2022 ASEE Annual Conference & Exposition

Location

Minneapolis, MN

Publication Date

August 23, 2022

Start Date

June 26, 2022

End Date

June 29, 2022

Conference Session

Environmental Engineering Division Technical Session 1

Page Count

9

Permanent URL

https://peer.asee.org/40380

Download Count

91

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Paper Authors

biography

Cara Poor University of Portland

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Dr. Poor teaches many of the integral undergraduate civil engineering courses at University of Portland, including fluids, environmental engineering, and capstone design. Dr. Poor is a licensed professional engineer with ongoing research in green infrastructure design, water quality, watershed management, and engineering education. She is currently developing new curricula for hydraulics, fluids, and environmental engineering labs, and conducting research on methods to improve conceptual understanding and critical thinking skills.

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biography

Kyla Burrill

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Kyla Burrill graduated from University of Portland in 2020 with a B.S. in mechanical engineering. She now works at HDR Inc. as a Transmission Line Engineer.

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Mason Jarvis

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Mason Jarvis is a 2021 graduate of the University of Portland now working as a dam safety engineer.

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Abstract

Constructed wetlands are becoming a common water treatment method, but most traditional environmental engineering classes do not cover natural treatment systems such as constructed wetlands. Traditional environmental engineering lab classes include biochemical oxygen demand (BOD), jar tests, alkalinity and hardness, etc. but lack any type of natural treatment component. To successfully design these systems, students need a strong conceptual understanding of the removal processes in constructed wetlands. Small, desktop constructed wetlands modules were created that fit on lab tables and allow students to work in groups of 3 or 4. Five modules were built for $625. The new constructed wetlands modules were used in an Environmental Engineering Lab with 25 students. Students analyzed influent and effluent samples for nitrate, ammonia, and phosphate from the constructed wetlands modules to evaluate different soil mixtures and residence times. Soil mixtures and residence times were selected based on recent published studies. A pre- and post-test was given to the students to evaluate how the lab improved their conceptual understanding and enthusiasm for the lab. The pre-test consisted of constructed wetlands conceptual questions, and the post-test included the same constructed wetlands conceptual questions in addition to questions that allowed students to rate the effectiveness of the lab. The students had an average gain of 0.18, and 76% of the students improved scores as a result of the lab. The students thought the lab improved their understanding of removal processes in constructed wetlands, and that the lab helped them visualize these processes.

Using commonly available materials, a low-cost constructed wetlands lab was created that improved student understanding of constructed wetlands and created enthusiasm for natural treatment systems. Students conducted tests that are similar to recent published studies in this area, and were exposed to common nutrient analysis techniques. Next steps include making the experiment more open-ended. Because there is no standard soil mixture for constructed wetlands, the best soil mixture for optimum removal is still unclear. Each group could develop their own soil mixtures using soil components provided by the instructor and the class could then evaluate the winning soil mixture based on optimum removal. Groups could also explore different plant types, and whether plant choice impacts removal. This lab provides an opportunity for students to learn about research and how design standards are created for natural systems, and can be easily modified depending on the research questions.

Poor, C., & Burrill, K., & Jarvis, M. (2022, August), Development of a Low-Cost Constructed Wetlands Experiment Paper presented at 2022 ASEE Annual Conference & Exposition, Minneapolis, MN. https://peer.asee.org/40380

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