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Date of Award

2020

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Environmental Engineering (PhD)

Administrative Home Department

Department of Civil and Environmental Engineering

Advisor 1

Brian Barkdoll

Committee Member 1

Robert M. Handler

Committee Member 2

Michael R. Gretz

Committee Member 3

David R. Shonnard

Abstract

Project decisions are currently decided primarily on initial costs, and neglect environmental and social aspects. In this study a new optimization algorithm has been developed based on the three-legged stool of sustainability, namely technical, environmental, and socioeconomic aspects. The new algorithm, entitled the Sustainability-Based Optimization Algorithm (SBOA) will minimize the average of normalized values of life-cycle costs, environmental impacts, and social objections subject to the constraint that all options will be acceptable. The optimal combinations of input variable values are found by optimization. The algorithm is demonstrated on algal biofuel production. The results show the minimum objective function occurs at the combination of input variables that minimizes each component of sustainability, namely CO2-reduction, environmental, and economic aspects. The advantage of this algorithm is that by considering all active and effective indicators together the most sustainably-robust result is found. The new algorithm is potentially applicable for various types of projects involved in resilient infrastructure.

Algal biofuels are of growing interest in the quest to reduce carbon emissions in the atmosphere but the sensitivity of the fuel production to various factors is not well understood. Therefore, the effects of temperature, light intensity, carbon concentration, aeration rate, pH, and time on the CO2 biofixation rate of Chlorella Vulgaris were investigated using experimental, and Genetic Programming (GP) modeling techniques. Chlorella Vulgaris was cultivated in a laboratory photobioreactor on a BG-11 medium. The developed GP model was used to optimize the CO2 biofixation based on the studied variables and produce a predictive equation. By using statistical measurements and error analysis, the predictive equation was shown to agree with the experimentally obtained values.

Project decisions are currently decided primarily on the environmental and techno-economic aspects, while social aspects are rarely considered. However, to ensure developing a sustainable technology, the social component must be considered too. Social sustainability is important because the perceptions of stakeholders can influence policies and regulations. Moreover, the evaluation of the effects of algal fuels in resource availability, human health risks, and land-use is critical to establish the necessary strategies to guide this alternative into a sustainable pathway.

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