CAREER: Moving beyond descriptive genomic studies - Applying theoretical ecology principles to predictably intensify anaerobic co-digestion processes

Microbial communities work together to process nutrients and organic matter in engineered and natural systems. It is difficult to predict how complex microbial communities will behave based on only what species are known to be present, because most prevalent microbes often change over time and from location to location, even as the community behavior stays the same. This work will develop a quantitative standard to describe the state of the microbial community for assessing bioreactor system performance. The research team will also create environmental engineering focused cartoons as part of an outreach effort. The cartoons will target underrepresented preteens and teens to increase scientific literacy and expand future participation in environmental engineering.<br/><br/>The overall research objective of this research is to apply the theoretical ecology principles to quantify the fundamental processes that drive microbial community architecture, functionality, and fluidity. The system of interest in this work will be anaerobic digesters during periods of stability, upset, and recovery. This research will test the hypothesis that strategic changes to the operational parameters of biotreatment systems can shape their microbial communities into predictable compositions that achieve the desired functional improvement. Three research objectives will be used to test this hypothesis. First, the dynamic microbiome structures and individual microbial interactions that occur in full-scale anaerobic bioreactors operated under non-co-digesting and co-digesting conditions will be quantified utilizing sequence data collected from full-scale facilities bi-monthly over a two-year period. Normal operational range benchmarks (NORBs) will be created to identify the natural variability that would be expected under stable operating conditions. Second, the NORBs for operational parameters including organic loading rates, volatile solids destruction, biogas and methane productivity, resistance, and resiliency for these same facilities will be quantified. Advanced statistical tools will be used to identify which operational parameters have the largest impact on microbiome structures observed in the first research objective. Finally, laboratory-scale anaerobic digesters will be used to determine the effectiveness of using changes in operational parameters to shape the microbiome structure for maximizing biogas productivity, resistance, and/or resiliency. The results of this work address the greatest weaknesses of the tremendous amount of sequence data generated in these systems; namely that it is largely descriptive in nature with limited utility for designing systems and predicting future performance. The educational and outreach phase of this work will identify the effectiveness of using sequential cartoons to increase the comprehension and retention of complex environmental issues in K-12 students with the goal of lowering barriers to participation in the field of environmental engineering.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.