Population growth and economic development are spurring increases in demand for new sources of energy and chemical precursors while simultaneously producing growing quantities of waste. Concurrently, there is growing agreement that waste streams should be viewed as valuable renewable resources rather than economic burdens. Current wastewater treatment operations are energy intensive, and ~3 % of electrical energy in the U.S. is used for wastewater treatment despite the fact that wastewater contains (1) organic materials possessing several times the energy needed for treatment, and (2) nutrients that can be used as a source to cultivate many times more organic biomass (e.g., through algae cultivation). When viewed in a biorefinery concept where the value of individual process streams is maximized, wastewater treatment provides an opportunity to produce energy and valuable chemicals while meeting treatment goals. Environmental engineers are uniquely positioned to play a central role in valorizing waste streams, developing new technologies that meet environmental quality goals while simultaneously recovering and producing energy, platform chemical feed stocks, and nutrients. The overall objective of the project is to advance hydrothermal catalytic technologies for converting waste-derived carboxylic acid/ester feed-stocks to hydrocarbon fuels. Development of economical technologies for valorizing waste streams has significant potential to transform waste treatment practices. Improved technologies for conversion of biomass-derived organics in water would also have broader impacts for the nascent lignocellulosic and algal biorefining industries, where feedstock dewatering/drying is a major hurdle to economic viability. This project will contribute to the training of at least two graduate students and will be used as a vehicle for recruiting and mentoring underrepresented minority undergraduate researchers. In addition, project participants will contribute to an environmental engineering and sustainability camp for high school girls that the I directs, at the University.
The proposed work supports larger collaborative efforts targeting development of integrated biological-catalytic pathways that are potentially transformative for valorization of municipal, agricultural, and industrial waste streams, including large quantities of organic wastes expected from proposed cellulosic biorefineries. Conversion of feedstocks in water is ideal because it eliminates the need for cost- and energy-prohibitive dewatering/drying steps. This study will be one of the first to focus on developing catalysts capable of sustained activity for both deoxygenation of waste-derived carboxylic acids/esters and in situ production of hydrogen to meet process needs. Proposed work will also improve understanding of the mechanisms responsible for catalyst deactivation and identify preventative and regeneration strategies for sustaining catalyst activity. A series of tasks were outlined to include examine catalysts with different combinations of lower-cost primary and secondary metals and to be compared for their dual functionality (acid/ester deoxygenation and in situ hydrogen generation). The most promising catalyst formulations will be extensively characterized, and their activity, longevity and deactivation mechanisms will be studied in detail under continuous-flow conditions in a packed bed reactor with both model compounds and waste-derived feedstock?s. Experimental results will be used as input for techno-economic and life cycle analyses to evaluate valorization potential and environmental sustainability.
