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Julia Ann Funk

Clemson University, PhD
EREF Scholar 2022

Anaerobic Degradation of Organic Fraction Municipal Solid Waste (OFMSW) with Fats, Oils, and Grease Waste (FOG) to Generate High Valued Volatile Fatty Acids

Project Description:
Redefining waste as a resource is paramount to solid waste management in the face of growing populations, limited land space, and high greenhouse gas (GHG) emissions. The questions to be answered are: Which wastes can be effectively utilized and what potential resources generated? Promising research demonstrates the feasibility of transforming the organic fraction of municipal solid waste (OFMSW) into a renewable energy source using anaerobic digestion (AD). This process provides an avenue for energy recovery in the form of biomethane production. However, the high concentrations of other gases such as carbon dioxide and hydrogen sulfide make purification to line ready natural gas costly and often inaccessible. Also, due to the heterogenous nature of OFMSW, the application of AD can be challenging, and the methane yields are not always sufficient to make the recovery of energy cost efficient. Therefore, flaring is often used to burn off biogas, escalating GHG emissions.

There is the potential for even greater resource production in shifting from methane generation to even higher valued intermediate metabolites involved in AD such as volatile fatty acids (VFAs) like propionate and butyrate which are traditionally derived from crude oil. Propionate and butyrate demand reached 470 kilotons and 105 kilotons in 2020, respectively. Conversion from influent organics to VFAs involve a series of biological reactions, hydrolysis, fermentation, and acidogenesis, which are carried out by a diverse network of microorganisms.

Producing VFAs would require manipulation of these reactions to boost substrate hydrolysis, enhance acidification, and suppress VFA consumption to methane. Lipid rich wastes, like fats, oils, and grease (FOG), are most ideal for this treatment due to high carbon content. FOG waste is generated primarily from cooking and food processing. Low concentrations can be sent to wastewater treatment plants and introduced during anaerobic digestion, but the remaining waste is sent to already crowded landfills. Lack of centralized treatment for high volumes makes it an easily attainable waste. However, the complex structure of FOG makes it difficult to biodegrade, requiring initial pretreatment processes to increase solubilization and consequent acidification.

This research proposes mixing FOG with OFMSW to mitigate potentially inhibitory effects and eliminate the need for pretreatment, generating a highly profitable resource. Exploration of optimal environmental conditions, process parameters, and microbial community dynamics to better generate VFAs from OFMSW and FOG as an alternative to petroleum-based sources will aid in producing a high valued resource from an abundant waste stream.

Julia Ann Funk began her education at Clemson University, graduating with a B.S. degree in Environmental Engineering in 2020. She continued for her MS in Environmental Engineering, graduating in 2021 . She is now pursuing a doctorate degree in Environmental Engineering and Science focusing on waste recovery at Clemson University and is expected to graduate in 2024. Julia Ann’s specific interest in solid waste management was ignited during her senior year of college while traveling to Havana, Cuba with a service organization to install membrane filters in homes without access to potable water. One of the villages she walked through actually had a surface water source but due to lack of waste collection and wastewater treatment, it was contaminated with trash, human, and animal waste. Julia Ann was able to see what a community looks like without access to necessities of life. This trip and project are what inspired her to continue her education in Environmental Engineering and revealed how having a passion for people can and will always be at the core of her career. These experiences have fueled her doctoral research, focusing on recovering resources from waste as a means of meeting needs of individuals and communities along with the growing need to protect and preserve our environment via sustainable management strategies.