Degree Type

Dissertation

Date of Award

2019

Degree Name

Doctor of Philosophy

Department

Agricultural and Biosystems Engineering

Major

Agricultural and Biosystems Engineering

First Advisor

Kurt A. Rosentrater

Abstract

The increasing amount of food waste (FW) is one of the most challenging problems around the world. The remarkable amount of FW produced is driven by various factors such as population growth, modernization, safety policy, culture, lifestyle, and human behavior. FW commonly will end up in the landfills and create more problems to the environment, ecosystem, human health, and economy. This organic waste is easy to decompose and emits greenhouse gases which will increase the global warming effect. Additionally, leachate from the landfill has the potential to contaminate nearby groundwater systems. It is important to divert FW from landfills and find a better option such as utilizing it to produce other value-added products. Depending on the FW composition, this waste has the potential to be used in fermentation technology and to be converted into ethanol as a primary product. Ethanol has a demand in different industries such as transportation fuel, cosmetic, pharmaceutical, and food. Additionally, waste from the fermentation process can be used as fertilizer in both liquid and solid form as it has a market value. In particular, solid waste stream can be burnt and converted into energy through combined heat and power (CHP) processes.

In this study, the main focus was to make a comparative assessment of the economic and environmental impact of FW fermentation on three value-added products: ethanol, liquid fertilizer, and bio-compost or energy. SuperPro Designer V9.0 simulation software was used to model the FW fermentation plant with commercial scale. Techno-economic analysis (TEA) and life cycle assessment (LCA) were used to determine the impact of this process.

A TEA study was conducted on five scenarios: (a) FW fermentation process with hydrolysis enzymes and 2-step distillation system, (b) FW fermentation process without enzymes and 2-step distillation system, (c) FW fermentation process without enzymes and 1-step distillation system (d) FW fermentation process without enzymes and membrane distillation, and (e) combined heat process (CHP) integrated with FW fermentation process. Discounted cash flow analysis was used to estimate the minimum selling ethanol (MSE) price when a net present value (NPV) is equal to zero, and the internal rate of return (IRR) is 10%. Results from this analysis showed that the lowest MSE was $1.88 per gallon for the scenario (e) which reveals integrated with CHP to be the most economical process compared to the other scenarios in this study.

An LCA was conducted to compare the environmental impact of FW fermentation process to landfilling method. The LCA scope was to evaluate the global warming potential (GWP) from each process. As expected, FW fermentation had the lowest environmental impact in comparison to the landfilling method. From the results, fermentation with membrane separation process had the least GWP impact given by 164.1 kg CO2-eq/1 Mg of FW compared to the other process depending upon assumptions.

Overall, this study has found the FW fermentation process to be a practical and sustainable way to manage FW rather than sending it to the landfills. This is an excellent opportunity to convert waste into cost-effective value-added products while minimizing the environmental burden.

Copyright Owner

Noor Intan Shafinas Muhammad

Language

en

File Format

application/pdf

File Size

150 pages

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