Research Seminars @ Illinois

Thermochemical Technologies as a Global Platform for Wastewater Residual Solids Management, Resource Recovery, and Emerging Contaminant Mitigation

Advisor: Professor Jeremy S. Guest

Abstract

Wastewater treatment is essential for protecting public and environmental health, yet the

management of wastewater residual solids (WWRS) remains energy-intensive, carbon-emitting,

and largely oriented toward stabilization and disposal rather than resource recovery. WWRS

concentrate organic carbon, nutrients, and anthropogenic contaminants removed during treatment,

making them a critical interface between wastewater infrastructure, climate impacts, and

environmental pollution. This dissertation investigates thermochemical technologies, particularly

hydrothermal liquefaction (HTL), as a system-level strategy for transforming WWRS management

toward decarbonization, resource recovery, and emerging contaminant mitigation.

The research develops an integrated quantitative framework to evaluate thermochemical pathways

across technical, economic, and environmental dimensions. First, a system-level modeling

platform was established to simulate HTL-based systems and link process performance with

sustainability outcomes through techno-economic analysis and life cycle assessment. The

framework identifies how biochemical composition and facility scale influence management cost

and greenhouse gas emissions. Second, the framework was applied to water resource recovery

facilities across the contiguous United States to identify deployment opportunities for HTL-based

WWRS management, integrating facility characteristics, regional economic and environmental

parameters, and infrastructure linkages such as oil refineries and fertilizer markets. Results show

that hundreds of facilities could simultaneously achieve cost savings and greenhouse gas

reductions, while hub-based deployment strategies could substantially expand participation by

aggregating solids from smaller facilities. Finally, a broader set of thermochemical technologies

was evaluated for emerging contaminant mitigation at the global scale. Literature evidence shows

that WWRS are highly concentrated and globally significant reservoirs of emerging contaminants

and that thermochemical technologies can achieve high destruction efficiencies. Country-level

sustainability results indicate lower greenhouse gas emissions but potentially higher costs in

certain regions relative to conventional practices.

Together, this work reframes WWRS management as a system-integration challenge linking

wastewater infrastructure with climate mitigation, circular resource transitions, and environmental

contaminant control. The findings provide quantitative guidance for the design and deployment of

thermochemical platforms capable of advancing sustainable wastewater solids management at

facility, national, and global scales.