Collaborative Research: Liquid Fertilizer and Engineered Carbon from pH-Swing Hydrothermal Carbonization of Animal Manure for Sustainable Circular Bioeconomy

Over one billion tons of nutrient-rich animal waste are produced annually in the United States, yet only a small portion is utilized, primarily as fertilizer. This project addresses a challenge of modern agriculture related to the sustainable management of animal manure, which, if not properly managed, can significantly impact the environment, public health, and the economy.

The team seeks to implement a novel process to optimize nutrient recovery and produce engineered carbon materials from animal manure which not only repurposes animal manure but also enhances its value as an efficient fertilizer. The project aims to improve the efficiency of resource utilization and impact in the agricultural sector. If successful, this technology will substantially alleviate the environmental, health, and economic burden associated with nutrient release into water bodies.

It may also enable local farmers and others to develop new products, thereby increasing revenues and reducing environmental pollution and waste disposal costs. The project will also provide unique training opportunities for graduate and undergraduate students.

This project aims to develop a novel hydrothermal carbonization (HTC) technology that efficiently recovers nutrients from animal manures while also producing value-added engineered carbons. In this pH-swing HTC process, nitrogen and phosphorus will be depleted from solid animal manure to liquid fertilizer by controlling the feedwater pH. This will also produce carbon-rich and low-impurity hydrochar, which will be further converted into engineered carbon for environmental applications.

To achieve the goals of this project, the following three objectives will be pursued: 1) develop a novel pH-swing HTC technology to recover nutrients into liquid phase from wet animal manures; 2) analyze the effects of different modification methods on the physicochemical properties as well as potential applications of the hydrochar; and 3) evaluate economic viability and environmental sustainability of nutrient recovery and engineered carbon synthesis. A range of laboratory experiments and model simulations will be conducted to explore and understand the effects of pH-swing HTC processes and carbon-modification methods on the quality of liquid fertilizer and engineered carbon derived from animal manure.

Technoeconomic analysis and life cycle assessment will be conducted to assess the environmental and economic benefits of nutrient recovery and engineered carbon synthesis. The success of the project will offer new insight into the chemical reactions and physical transformations occurring during the HTC of animal wastes. It will also be a significant step towards scaling-up and commercialization of the pH-swing HTC technology for sustainable circular bioeconomy.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.