Oregon State University, Ph.D.
Evergreen Surety Bond Scholar 2019
Anaerobic Co-digestion of Organic Solid Waste for Increased Methane Production
Ashley’s work focuses on improving a process that is already occurring at wastewater treatment plants across the country. This process is called anaerobic digestion and basically serves as the final step in wastewater treatment. The anaerobic digester is where all of the sludge and solids are sent and are broken down by microorganisms in the absence of oxygen. This process naturally produces methane gas, which can be used to produce electricity, but most treatment plants flare the gas onsite because not enough is made to capture it and use it. In order to increase gas production and make the recapture of methane for electricity production more economically viable, the anaerobic digesters are fed another carbon source, typically a food waste. Ashley works specifically on fats, oils, and greases (FOG) which are collected from restaurant grease traps. Anaerobic digesters are fairly sensitive to process changes, so Ashley is looking at how to optimize the system by altering the microbial community that exists in a digester. She is doing this by stressing the system and overfeeding it so that, ideally, the weaker microbes, or those that are not attuned to dealing with fats, die out and those that are better at handling fats make up a larger portion of the population. She monitors both reactor performance parameters such as gas production, methane composition, pH, and solids content while also sequencing DNA extracted from the sludge to observe how the microbial has shifted throughout an experiment. These results can be used to help operators better adapt their systems to the digestion of fats, oils, and greases and will hopefully allow for existing system to increase their loading rates allowing for more food waste to be diverted from landfills in the future.
Ashley Berninghaus is a 4th year Ph.D. student in the School of Chemical, Biological, and Environmental Engineering at Oregon State University where her work is centered on biologically based renewable energy and water treatment systems. She earned a B.S. in both Chemical and Biological Engineering at Montana State University in 2015 and plans to finish her Ph.D. in Environmental Engineering in September of 2021. Ashley’s interest in renewable energy and water treatment began when she started undergraduate research focused on algal biofuels grown on wastewater. This led her to anaerobic digestion of waste algal biomass as a way to complete the life cycle of algal biofuels. After graduating, she was an intern at the National Renewable Energy Lab where her work focused on catalytic upgrading of pyrolysis products, an abiotic method of biofuel production. At Oregon State, Ashley has worked extensively on the anaerobic co-digestion of fats, oils, and greases in order to optimize the process and increase the methane production potential of these systems. She specifically focuses on how controlled upset events can help to shift the microbial community in a favorable way.