Influence of Diel Cycling, Nitrate, and Salinity on Ammonium Removal in Open Water Treatment Wetlands

* Honorable Mention *

PROJECT NUMBER: 37

AUTHOR: Julia Siegmund, Civil and Environmental Engineering | MENTOR: Jonathan (Josh) Sharp, Civil and Environmental Engineering

ABSTRACT

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Shallow open water wetlands are a unique type of engineered wetland that remove nutrients from impaired waters through microbial processes within a benthic and photosynthetic biomat. While past research has focused on nitrate attenuation in demonstration scale open water wetlands, the potential for these systems to remove ammonium remains unknown. This study used laboratory scale biomat flow through experiments to investigate how photosynthesis, salinity, and simulated mixing of nitrate and ammonium impaired waters influence ammonium removal processes within the photosynthetic biomat. We hypothesized that diel cycling is necessary for maximum ammonium removal by wetland biomat and that a mixed influent would enhance removal, decreasing salinity inhibitions. Results indicate that the biomat was able to remove ammonium through biological processes and physical sorption. Surprisingly, biomat in dark conditions performed as well as biomat in diel cycling conditions, opposing our first hypothesis. Significantly increased sorption was observed in biomat under dark conditions. Biomat with mixed influent removed significantly more ammonium, and biomat with saline influent removed significantly less ammonium, confirming our remaining hypotheses. Open water wetlands have demonstrated effective removal of ammonium in a laboratory setting, with improved removal from a mixed influent showing the potential to reduce inhibitions by salinity.

VISUAL PRESENTATION

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AUTHOR BIOGRAPHY

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Julia is a senior in the Civil and Environmental Engineering Department, graduating in May 2020 with a B.S. in Environmental Engineering and a minor in Biology. She has been working as an undergraduate research fellow in the Geo-Environmental Microbiology Lab in Dr. Josh Sharp’s group for 2.5 years, working closely with PhD candidates Michael Vega and Laura Leonard. She has worked on projects investigating the feasibility of using open water wetlands to treat impaired waters and understanding nitrogen removal processes in wetlands, as well as understanding the impact of bark beetle infestations and climate change on soil microbial communities in Rocky Mountain forests. Julia will begin working as a water resources EIT after graduation, and hopes to pursue graduate research in hydrology and/or ecology in the future.

Sponsored by Phillips 66