Date of Defense

4-19-2022

Date of Graduation

4-2022

Department

Biological Sciences

First Advisor

Silvia Rossbach

Second Advisor

Chris Jackson

Third Advisor

Aurora Mokris

Abstract

Pre-consumer food waste, hay, and woodchips were composted using two different methods of static composting: forced aeration (FA) and natural aeration (NA). The composting process was performed during the winter and summer for 106 and 124 days, respectively. The composting process for both winter and summer processes did not reach the temperature above the 40°C threshold of the thermophilic stage in composting. The microbial communities present during different timepoints (start, peak, and final) along the composting process were analyzed with DNA sequencing techniques and visualized using QIIME 2, an open-source bioinformatics platform. The microbial communities of the winter and summer compost had higher abundances of Firmicutes at the start but lessened throughout the remainder of the composting process. The opposite trend was seen in Alphaproteobacteria and Bacteriodia for both winter and summer composting processes. The final timepoints in the summer compost showed higher species richness when compared to the winter compost. However, the higher species richness may have negatively affected the phytotoxicity levels of the mature summer compost. The phytotoxicity data showed lower germination rates and fresh/dry weights for the summer compost at statistically significant levels irrespective of the treatment (FA or NA). A weighted Unifrac plot showed that the winter final samples were more similar to the peak samples for the winter and summer compost rather than to the summer final samples meaning that the winter compost might not have been fully matured by the end of the compost process. The overall conclusions that were drawn from this study were that the thermophilic stage of the composting process is an important intermediate needed to produce a good mature compost product regardless of season; the forced aeration compost method produced better compost in the winter trials, but there isn’t sufficient evidence to suggest that it is a better method given the data in this study; and that the microbial communities play a significant role in creating a good compost product.

Access Setting

Honors Thesis-Open Access

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