580 California St., Suite 400
San Francisco, CA, 94104
Key research themes
1. How do iron-based materials and redox catalysts mediate contaminant degradation through reductive and advanced oxidation processes?
This theme focuses on the application and mechanistic understanding of iron-containing materials and catalysts in facilitating reductive dechlorination and advanced oxidation reactions to degrade persistent chlorinated organic contaminants and other xenobiotics. Iron oxides, blast furnace dust, alloyed iron catalysts, and Pd-catalyzed Fenton reactions enhance contaminant transformation by accelerating electron transfer, improving hydroxyl radical generation, or serving as electron shuttles. The development of heterogeneous catalytic systems aims at improving degradation efficiency, reducing drawbacks like sludge formation, and enabling treatment under varied environmental conditions.
Key finding: Demonstrated that blast furnace dust (BFD), an iron oxide-rich steel industry by-product, effectively degrades chlorinated organic compounds (e.g., PCE, cis-DCE) and endocrine disrupting compounds with removal efficiencies... Read more
Key finding: Elucidated compound- and system-specific factors governing reductive transformations, including reductive dehalogenation of chlorinated ethenes and reduction of nitroaromatics by biotic and abiotic iron and sulfate-reducing... Read more
Key finding: Developed a novel accelerated catalytic Fenton (ACF) system coupling Pd-activated hydrogen to rapidly reduce Fe(III) back to Fe(II), enhancing hydroxyl radical production and contaminant degradation efficiency at trace... Read more
Key finding: Provided a comprehensive review highlighting that substitution of iron oxides with other transition metals enhances heterogeneous Fenton catalytic activity via redox pair conjugation and generation of oxygen vacancies,... Read more
Key finding: Reviewed how biochar's intrinsic redox-active moieties (quinones, phenolics) and associated metals contribute as electron donors, acceptors, or shuttles facilitating redox reactions including contaminant degradation and... Read more
2. What are the mechanistic and operational factors influencing the removal of emerging organic contaminants and micropollutants in wastewater treatment systems?
Research under this theme investigates the occurrence, transport, transformation, and removal efficiency of diverse emerging contaminants (ECs) including pharmaceuticals, endocrine disruptors, pesticides, and industrial chemicals in municipal wastewater treatment plants (WWTPs). It encompasses process design factors such as activated sludge retention times, conventional versus biofilm reactors, and advanced oxidation disinfection, with a focus on improving degradability and minimizing residual toxicity. This theme is critical for understanding and optimizing wastewater treatment to mitigate EC release into aquatic environments.
Key finding: Provided comprehensive longitudinal monitoring of 63 emerging contaminants across four WWTPs employing varied conventional treatment technologies, demonstrating limited removal of many ECs during activated sludge processes.... Read more
Key finding: Investigated eight WWTPs with various technologies (activated sludge, MBBR, MBR) assessing site-specific factors influencing removal efficiencies of contaminants of emerging concern (CECs). Key findings include negative... Read more
Key finding: Demonstrated the efficacy of a novel continuous-flow ozonation system in degrading a mixture of six representative micropollutants and sanitizing biologically contaminated municipal wastewater effluent. The system achieved... Read more
Key finding: Reviewed biological sludge reduction through degradation of endogenous decay products (inert solids) in activated sludge systems and membrane bioreactors, showing that longer solids retention times (SRTs) enable enhanced... Read more
3. How do plant-microbe interactions and phytotechnologies influence contaminant stabilization and microbial community dynamics in contaminated soils and mine wastes?
This research theme addresses the use of phytoremediation, especially actinorhizal alders and their symbiotic nitrogen-fixing bacteria (Frankia) and ectomycorrhizal fungi, for the stabilization and improvement of contaminated substrates with complex metal mixtures, such as gold mine waste rock. Studies focus on soil physicochemical amelioration, microbial community shifts, and metal immobilization without hyperaccumulation into biomass, providing sustainable in situ reclamation strategies.
Key finding: Demonstrated that inoculated alders (Alnus crispa and A. glutinosa) effectively phytostabilized metal-contaminated gold mine waste by neutralizing soil pH and reducing extractable metals by up to two-fold without metal... Read more