Mapping the phosphorus recovery benefits from centralized infrastructure in the food-energy-water nexus

Phosphorus (P) is a critical nutrient in maintaining security and resiliency in the Food-Energy-Water nexus. Inefficiencies in the current usage of P fertilizers has led to excessive mining of phosphate rock and loss of excess P to surface water bodies, contributing to eutrophication. The reduction, recovery, and reuse of P throughout the agricultural system can assist in generating a more effective circular P economy. In the United States (US), corn ethanol biorefineries are major intermediate agricultural processors of biofuels that can recover P as a renewable P (rP) fertilizer, calcium phytate. This recovery also results in reduction of P in biorefinery distillers grain feed, an animal feed co-product, and associated animal wastes. On a global scale, the transition of animal-fed soybean meal to a human-grade soy protein product, such as soy protein concentrate (SPC), can be used to replace P-intensive animal proteins. The overarching goal of this work was to model and map the potential benefits associated with P recovery at US corn ethanol biorefineries and a global adoption of SPC protein. The primary objectives include: (1) mapping generation potential of rP from biorefineries across the US as compared to rP potential from water resource recovery facilities (WRRFs); (2) modeling biorefinery distillers grains flows across the US and potential P reduction benefits from animals fed distillers grains with reduced P; (3) elucidating localized P recovery and reduction benefits from biorefineries on a watershed-level in the Midwest US and comparison to state nutrient loss reduction strategy goals; and (4) modeling and mapping global P reduction and rP recovery benefits of SPC protein production from animal-fed soybean meal, including replacement of animal-based proteins. The first three objectives focused exclusively on improving P circularity within existing agriculture in the US. The first analysis estimated that biorefineries in the US can generate twice the amount of rP fertilizer as WRRFs. Biorefineries were also found to be better co-located with P fertilizer utilization of nearby croplands than WRRFs. The second analysis estimated that most distillers grain feed was utilized in the same state it was produced, and that P reduction potential in wastes of animals fed reduced P distillers grains was nearly double that from human waste at WRRFs. Both analyses showed that biorefinery P recovery benefits were largely concentrated in the Midwest US, where most biorefineries are located. The final biorefinery analysis focused specifically on P recovery benefits in watersheds of six Upper Midwestern states, finding that sixty-six watersheds could realize localized P benefits from recovery. An estimated 79% of watersheds with a biorefinery were also found to be capable of generating greater P reductions from animal wastes at local concentrated animal feeding operations using reduced P distillers grains than could be reduced from WRRF waste. While traditional P regulations in the US focus on sources such as WRRFs for reductions, corn biorefineries were found to be capable of producing much larger local benefits for P circularity. To assess P benefits on a global scale, the last objective focused on diverting animal-fed soybean meal to SPC protein for human use, finding that complete replacement of animal with SPC protein could generate an estimated 90% reduction in total global P utilization required for animal protein production. Additionally, the recovery of rP during SPC processing could account for 17% of total P fertilizer utilization for global soybean production. Overall, this work showed the pivotal role biorefineries can play in improving P circularity in the US and their role in the Food-Energy-Water nexus, particularly in the Midwest region. Additionally, the continued growth in SPC protein products as an alternative protein source to animals was shown to have major global P utilization benefits that can provide greater resiliency in the food production system.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Environ Engr in Civil Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Ruffatto, Kenneth Joseph

Contributors dc:contributor

• Cusick, Roland D
• Guest, Jeremy S
• Margenot, Andrew J
• Muenich, Rebecca

• Phosphorus Recovery
• Biorefineries
• Soy Protein
• Watershed

Statement dc:rights

• Copyright 2024 Kenneth Ruffatto

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/124248

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F124248