Anaerobic digesters are specialized vessels that hold microbial communities that decompose organic materials without oxygen present. There are many diverse applications for anaerobic digesters such as the treatment of biodegradable waste and sewer sludge. Specifically, anaerobic vessels that house methanogenic communities have great potential to break down and utilize paper manufacturing waste. In our lab, there are two anaerobic digesters that have been studied for the past two decades. The goal of this research was to design and implement new anaerobic digesters to improve the stability of the anaerobic microbial communities. To complete this task, I did research on methanogenic communities and compared our current anaerobic digesters. After this, there were two versions of the prototype digester created with improvements made to the waste and feeding port. I tested the integrity of the vessel by submerging it under water and then pumping it with nitrogen gas to ensure no oxygen was present. The vessel was then filled with 10 ml of acetate feed with resazurin color indicator which was incubated for 10 days. I concluded that the vessel was able to maintain an anaerobic environment and we ensured that no oxygen could contaminate the vessel by siliconing the tubes and ports. The final vessel included access ports to take samples and more security against oxygen seeping in. We then moved the microbial communities from the current anaerobic vessel to the new anaerobic vessels. Furthermore, we tested how fast the communities processed the acetate feed (which was given daily) and the types of microbial communities in the reactors. We found that the new digesters allow for easy sampling and that they process feed almost immediately. This research can be used to improve how anaerobic digestion is used in the treatment of paper manufacturing wastewater and testing the microbial communities in wastewater.

Wastewater pollution is a grave concern for public health worldwide, and the U.S. wastewater treatment system can be improved to extract pollutants to the highest level more adequately. One way to better extract pollution left after treatment is by using the metabolic capacity of microbiomes in the soil. This study tests microbiome pollution extraction potential by measuring functional gene abundance according to soil depth in poplar tree reactors irrigated with synthetic wastewater. I collected and extracted DNA from soil samples from 9 reactors at two different depths. I then performed ddPCR on the extracted DNA to quantify the nitrogen-cycling genes amoA, nifH, and nirK, at different depths. I also tested the 16S gene to quantify total soil microbiome biomass. Biomass and functional gene abundance did not vary by depth, but they did vary by season. Biomass additionally varied by treatment group. Study findings could guide the design of a wastewater facility to maximize pollution extraction.

Sustainable and effective wastewater treatment is a growing field that incorporates biological and environmentally friendly solutions to many stages in the wastewater treatment process. This study explored the tertiary treatment of wastewater through poplar tree bioreactors with a focus on nitrate and other nitrogen compounds. Synthetic secondary wastewater was made and fed to the bioreactors. The bioreactor effluent was then collected and analyzed. Previous work has shown significantly decreased levels of nitrate found in the poplar bioreactor effluent when compared to the control bioreactors. An important aspect of this bioreactor system is its ability to simultaneously produce biomass. To incentivize this project, the biomass produced can be sold to be synthesized into bioethanol. The latter portion of this study was a woody biomass analysis to compare the different growths between the treated and untreated poplar tree bioreactors. The trees were coppiced, processed, and dried at 60C for roughly seven days until there were little to no changes in the mass between hourly measurements. A leaf nutrient analysis of the treated and untreated trees was made to trace nitrogen pathways. Upon visual inspection, the treated trees appeared significantly larger and more developed. The result of the biomass analysis indicated that were was increased growth in the treated poplar bioreactors. Some of the treated trees had produced over five times the biomass of the untreated trees. The results of the leaf analysis showed greater carbon and nitrogen concentrations in the treated poplar leaves. Additionally, a higher percentage of nitrate was found in the leaf composition of the treated poplars. These results demonstrate that the treated bioreactors possessed an increased nitrogen uptake due to the increased presence of nitrate in the wastewater. There also appears to be a strong correlation between the treatment of the poplar tree bioreactors and their increased growth.