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.