Grantee Research Project Results
Final Report: Enrichment of Microbial Communities for Biogas Production in High-Solids Environments
EPA Grant Number: SU835688Title: Enrichment of Microbial Communities for Biogas Production in High-Solids Environments
Investigators: Simmons, Christopher W , VanderGheynst, Jean S , Claypool, Josh , Drechsler, Kelly , Reese, Morgan , Pace, Sara
Institution: University of California - Davis
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2014 through August 14, 2015
Project Amount: $14,473
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2014) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Air Quality , P3 Awards , Sustainable and Healthy Communities
Objective:
The objective of our research has sought to rectify this problem by enriching for a microbial community that increases biogas production at these elevated solids loadings using manure as asubstrate. To achieve this we sought to enrich for microorganisms that are capable of 1) surviving in high-solids conditions, 2) capable of breaking down recalcitrant organic matter, 3) and producing methane. To accomplish these goals, we selected microbial communities most adept at these tasks and then enriched for the most robust microorganisms. The community selected for breaking down recalcitrant organic matter was derived from compost and the community and the community for methane production was selected from dairy manure. From these two sources of inoculum, conditions were supplied to stress the microorganisms to select for the highest performing microorganisms at high-solids conditions.
Summary/Accomplishments (Outputs/Outcomes):
The enriched communities for high-solids anaerobic digestion have been developed and appear to be producing biogas at elevated rates as reported in literature (Abbasi et al). It was found that utilizing compost as a source of inoculum has increased the rate of methane production over that of the dairy manure. It has also been shown that the maximum rates of methane production in a 30% solids batch culture can match that of a 20% solids community. While activity was recorded up to 40% solids, the activity of the community was lower than the 30% solids community and work was continued with the 30% solids community. The desired rates for batch times have not yet been achieved and some hypothesis have come about to increase biogas production rates to decrease the length of time needed for each batch. It is not known what total biogas yield from the reactors will be achieved as batches have not run to completion, but biogas quality has stayed greater than 60% methane. DNA has been collected from the organisms present in the digesters and will be identified using genetic markers.
Preservation work while started is currently incomplete and will demand more rigorous testing. Initial findings have suggested that preserving methanogenic communities can be accomplished using all proposed methods. Currently one method for cryopreservation has been extremely successful at restoring high levels of methanogenic activity while the other cryoprotectant appears to have no effect over that of just freezing the culture. Our industrially-relevant method for preserving our community has been successful with reduced levels of methanogenic activity. Changes in the preservation protocol has been discussed and is undergoing testing currently. It has also been achieved to use as little only 10% inoculum upon starting a new digester.
Conclusions:
A high-solids community has been developed that can also be shelf-stored and reactivated upon rehydration with new substrate. It is anticipated that improvements in shelf-stability and gas production rates can be achieved upon further work. Additionally, DNA will be identified in the upcoming months to inform us with regards to what microorganisms are present in the digester and can survive under the stressed conditions.
Supplemental Keywords:
waste to energy, biodiversity, biogas, anaerobic digestion, microbial communitiesRelevant Websites:
Simmons Group Youtube Channel Exit
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.