Monitoring dynamics of microbial communities in algae cultures grown at different scales for the bioprocessing of food waste within the context of a Circular Economy.
Supervisor: Alison Smith Payam Mehrshahi (Univ. Cambridge)
In recent years circular economy models have attracted interest as a potential solution for different environmental challenges. In the context of food waste remediation, the use of microorganisms is routinely employed in such circular systems. Microalgae are photosynthetic microbes that can simultaneously produce biomass than can be used for feed supplements, as well as assimilating nutrients (N, P, C) from different substrates, including organic waste. By combining microalgal cultivation with the degradation of anaerobically digested fruit and vegetable waste, a gap in a microbial centric waste remediation process can be filled. Even though use of microalgae at a small scale has shown promise, scaling up microalgae cultures for industrial application still faces important challenges. In this study, both the treatment of anaerobic digestates (AD) and the monitoring of microbial contaminants in Chlorella vulgaris cultures are addressed. In a laboratory environment, the conditions for the growth of the algae in AD were standardized and it was found that the selected algal species had an optimal growth rate at a 1%-2.75% concentration of AD. Secondly, a methodology was devised for analysis by flow cytometry (FC) of microbial growth dynamics in cultures grown in different environmental conditions. This methodology was then applied to monitor the microbial populations dynamics in cultures grown at different scales (400mL – 10L) inside the Algal Innovation Centre (AIC) pilot facility of the University of Cambridge. These observations coupled with physiochemical parameter testing of the cultures, enabled quantitative determination of microbial activity (cellular and metabolic) within cultures. Altogether, these insights enable the improvement of microalgal culturing techniques for treatment of AD waste within a circular economy system.