Publications

The purpose of this study is to develop regression models that describe the role of process conditions and feedstock chemical properties on carbonization product characteristics. Experimental data were collected and compiled from literature-reported carbonization studies and subsequently analyzed using two statistical approaches: multiple linear regression and regression trees. Results from these analyses indicate that both the multiple linear regression and regression tree models fit the product characteristics data well. The regression tree models provide valuable insight into parameter relationships. Relative weight analyses indicate that process conditions are more influential to the solid yields and liquid and gas-phase carbon contents, while feedstock properties are more influential on the hydrochar carbon content, energy content, and the normalized carbon content of the solid.

Although there are numerous studies suggesting hydrothermal carbonization is an environmentally advantageous process for transformation of wastes to value-added products, a systems level evaluation of the environmental impacts associated with hydrothermal carbonization and subsequent hydrochar combustion has not been conducted. The specific objectives of this work are to use a life cycle assessment approach to evaluate the environmental impacts associated with the HTC of food wastes and the subsequent combustion of the generated solid product (hydrochar) for energy production, and to understand how parameters and/or components associated with food waste carbonization and subsequent hydrochar combustion influence system environmental impact. Results from this analysis indicate that HTC process water emissions and hydrochar combustion most significantly influence system environmental impact, with a net negative GWP impact resulting for all evaluated substituted energy-sources except biomass. These results illustrate the importance of electricity production from hydrochar particularly when it is used to offset coal-based energy sources. HTC process water emissions result in a net impact to the environment, indicating a need for developing appropriate management strategies. Results from this analysis also highlight a need for additional exploration of liquid and gas-phase composition, a better understanding of how changes in carbonization conditions (e.g., reaction time and temperature) influence metal and nutrient fate, and the exploration of liquid-phase treatment.

16 ing imagination, intuition and deliberate choice”(CV Engineering 2014). There is a simple answer, then, to the question—we teach students to speak the language of engineering by providing instructional environments that inspire them to practice the art of arriving at a good solution. Just like a road trip for a family vacation, the fun is not in the destination, it is in the process of getting there. For this to happen, students need to be immersed in the process of engineering design, which requires both creativity and critical thought. Critical thinking can be described as a subset of three types of thinking: reasoning, making judgments and decisions, and problem solving (Willingham 2007). Research shows that critical thinking associated with engineering content can be facilitated through active learning (eg, Prince 2004), and it can be further stimulated and evaluated through the proposition of reflective questioning of …

This paper describes the Environments for Fostering Effective Critical Thinking (EFFECTs) pedagogical framework that has been developed and implemented across the civil and environmental engineering curriculum at the University of South Carolina. Thirteen unique EFFECTs have been created to date, impacting seven different courses. This instructional approach has been used in courses at all undergraduate levels, from first-year introduction courses to upper division elective courses. The cumulative application of EFFECTs facilitates the integration of technical and professional skills to meet programmatic student outcomes. This paper provides a map of the ABET and ASCE student outcomes that are addressed with EFFECTs, with appropriate examples from different EFFECTs modules. In terms of professional student outcomes, the EFFECTs framework is designed to enhance student communication skills, teamwork, and knowledge of contemporary issues. In addition to these three core outcomes, each EFFECT can incorporate other professional skills, depending on the nature and content of that particular EFFECT. The implementation of EFFECTs has reached a point where most, but not all, upper division students (seniors) have been exposed to the EFFECT approach at least once during their academic program. Survey results on student self-perceptions of professional skill development are reported in this paper. Based on those findings, teamwork is the highest rated outcome. Professional skill development was also found to improve significantly when students are exposed to EFFECTs in more than one course.

Hydrothermal carbonization (HTC) is a thermal conversion process that has been shown to be environmentally and energetically advantageous for the conversion of wet feedstocks. Supplemental moisture, usually in the form of pure water, is added during carbonization to achieve feedstock submersion. To improve process sustainability, it is important to consider alternative supplemental moisture sources. Liquid waste streams may be ideal alternative liquid source candidates. Experiments were conducted to systematically evaluate how changes in pH, ionic strength, and organic carbon content of the initial process water influences cellulose carbonization. Results from the experiments conducted evaluating the influence of process water quality on carbonization indicate that changes in initial water quality do influence time-dependent carbonization product composition and yields. These results also suggest that using municipal and industrial wastewaters, with the exception of streams with high CaCl2 concentrations, may impart little influence on final carbonization products/yields.