Date of Graduation

12-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Chemical Engineering

Advisor/Mentor

Greg Thoma

Committee Member

Lauren Greenlee

Second Committee Member

Jennie Popp

Third Committee Member

Marty Matlock

Fourth Committee Member

Jamie Hestekin

Keywords

eutrophication, life cycle assessment, nutrient recovery, struvite, wastewater treatment

Abstract

As the supply of phosphorus decreases, nutrient recovery in municipal wastewater treatment has become an important area of research. Recovery methods for phosphorus-containing fertilizers, such as struvite, and other products are currently being developed and assessed for their efficiency and economic feasibility. Potential environmental impacts from nutrient recovery are also being assessed as design for the environment is important, especially with regards to the eutrophying potential of phosphorus in phosphorus-limited freshwater aquatic systems. Life cycle assessment (LCA) is a tool that can be used to estimate potential environmental impacts of a product or service focusing on its entire life cycle. This research applies LCA to determine potential environmental benefits, as well as unforeseen burdens, that could be realized from implementation of nutrient recovery at the treatment facility scale and national scale. First, this dissertation provides an LCA of a novel electrochemical struvite precipitation method using a sacrificial Mg anode at the facility scale, the first analysis to do so (Chapter 2). Second, spatially explicit eutrophication potential from wastewater treatment discharge in the U.S. including potential changes from nutrient recovery are modeled (Chapter 3). Additionally, the work presents a new model in which eutrophication potential is disaggregated to determine whether phosphorus loading is local or resulting from upstream phosphorus emissions. In addition to expanding the body of knowledge in the realm of phosphorus recovery, these two studies also employ LCA methods that are growing areas of research: prospective and spatially explicit LCA. As emerging nutrient recovery technologies evolve, employing these developing fields of LCA can help guide decisionmakers in developing strategies to not only conserve phosphorus through nutrient recovery, but also to effectively mitigate eutrophication potential where point-sources of phosphorus are significant.

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