Understanding microbial community dynamics in food waste anaerobic digestion

Anaerobic digestion (AD) uses complex microbial communities to recover resources from organic waste in the form of biogas and a nitrogen digestate. Biogas can be burned in a combined heat and power engine to produce heat for local use and "green" electricity that can be exported to the grid. This project will consider how microbial communities alter during the AD of food waste in commercial systems, where key considerations are generating a consistently high level of conversion of waste to high quality biogas. Samples will be collected from D&F Solutions facilities, with consideration of biological and technical replication and, process differences between operations at different sites. The project may also consider the dynamics of digester start-up following vessel cleaning.

Initial work will consider historical data from D&F sites, looking for correlations between feedstock composition and biogas production. The work will also compare at least two different methods for the absolute quantification of 16S rRNA amplicon metagenomics as a way of tracking microbial community compositional changes. Other methods that may be applied to gaining more insight into the detailed responses of the microbial communities to feedstock and process changes might include shotgun metagenomics and metabolomics.

Variables that might be considered as a way of understanding whether these AD processes can be enhanced will include waste stream composition, feeding regimes and additions of process enhancers such as trace elements. Where testable hypotheses are generated from data collection and analysis, these may be tested using lab-based AD systems to infer how these changes might impact on process scale operations.