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.