Rice University, Ph.D.
Waste Industries Scholarship Honoring Lonnie C. Poole Jr. 2019
Developing Novel Methods for Resource Recovery: The Future of Food Waste Management
An astounding 39.62 million tons of food waste is produced each year in the U.S., the vast majority of which goes to the landfill. Food waste is a vastly underutilized resource that contains large amounts of bioavailable nutrients and resources. Acid fermenters are microbially based platforms that can break down food waste into volatile fatty acids. Additional biological or chemical processes can turn these volatile fatty acids into many different organic chemicals. As such, volatile fatty acids are a potential chemical production platform to replace the petroleum and oil-based platform that is used to produce a wide range of products today. The conception of this platform was relatively recent, so there remains much to be understood about acid fermenters and appropriate valorization processes to pair them with. One of the goals of Zach’s research is to elucidate how different functional groups of microorganisms in acid fermenters break complex organic matter down into simple volatile fatty acids. This knowledge will help determine how the variability in the incoming organic waste stream affects the composition of the effluent stream. Additionally, a fundamental understanding of the interactions will give us greater control over the function of the microbial community. Greater control of microbial community function means greater control over the profile and concentration of volatile fatty acids in the effluent stream. Volatile fatty acid composition is extremely significant because it determines the effectiveness of the downstream valorization process. Another related and important objective of Zach’s graduate career is developing biologically-based valorization processes that can be paired with acid fermentation. Zach is currently working on a project to transform volatile fatty acids and the accompanying organic nitrogen into microbial protein for livestock feed. Nitrogen is also a large component of organic waste streams such as food waste. Current approaches to biological nitrogen removal from waste streams involves the transformation of organic nitrogen into nitrogen gas, which is then released to the atmosphere. Concurrently, massive amounts of energy are used to fix atmospheric nitrogen back into reactive nitrogen for fertilizer to grow crops for food and feed. Technologies like microbial protein grown from volatile fatty acids and the residual organic nitrogen in organic waste streams offers a solution that directly addresses this inefficiency.
Zach was born and raised in the suburbs outside of Seattle, Washington. In 2010, he entered the University of Washington (UW) to pursue his undergraduate degree. While at UW, he participated in the UW Biodiesel Cooperative, a student organization working to recycle the campus’s used cooking oil into biodiesel. Zach’s senior design project involved a life cycle analysis on unique solar cells made from earth abundant materials. In 2014, he graduated from UW with a B.S. in Chemical Engineering. After undergrad, Zach went to work for Stericycle as an environmental specialist. Stericycle embedded Zach at the Allen Institute where he managed all chemical, biological, and radioactive waste produced by the research facility. After working for Stericycle for a year he also began volunteering in the lab of Dr. Mari Winkler every day after work. For another year Zach worked in Dr. Winkler’s lab to characterize the growth kinetics of Ammonia Oxidizing Bacteria. In 2018 he began his Ph.D. in Environmental Engineering at Rice University. Zach works with his advisor, Dr. Lauren Stadler, on resource recovery from food waste using microorganisms. He specifically studies acid fermenters that process food waste into volatile fatty acids, as well as the ensuing processes to turn those volatile fatty acids into more valuable compounds. Zach is on track to graduate in 2022.