1. Influence of microbial communities on methane production in Anaerobic Digestion 17-Novermber-2010 Robert Ferguson

2. Project Summary To optimise AD by understanding the microbial ecology of the process. Research has shown that monitoring operational parameters is not sufficient to fully understand the process (Fernandez,1999). Molecular techniques will be used to analyse the microbial community. Project dates: March 2010 – Feb 2013

3. Objectives The AD process will be manipulated between stressed and optimal conditions to investigate: The factors affecting the community structure. The influence of community structure on performance. The possibility of controlling a shift community to improve the process. The optimisation of different feedstocks and co-digestion.

4. Manipulation Community structure Change in Community structure negative positive Process change Analysis of community and process Performance change Change in feed

5. Potential benefits Improved understanding and control of the AD process. Better utilisation of multiple waste sources, enabling flexibility in process control (meeting goals set by UK Government for exploitation of AD). Contribute to meeting UK and EU renewable energy and GHG emissions targets. AD optimisation will lead to improved return on technology investment via improved yields and stability.

6. Current knowledge Previous studies have concentrated on analysing performance parameters such as pH and methane production. When microbial analysis has been carried many studies have only characterised the species present and have not looked at structure and interactions. Often studies sack the replication of rigorous statistical analysis of the microbial community. However....

7. Current knowledge This has been shown in relation to increasing concentrations of VFA, pH, Hydrogen and ammonia and is a fairly universal reaction. Acetoclastic Hydrogenotrophic Stress

8. How will it be done Lab scale reactors Manipulated between stressed and optimal operation Characterisation of communities Use ecological parameters of stability to understand the influence of community structure on performance (Neubert MG, Caswell H. 1997). Microbial analysis Lipid analysis Molecular analysis Statistical analysis Multivariate analysis of community against process resilience analysis stressed optimal stressed optimal

9. Glycerol trials Ctrl 3%

10. Progress New medium scale AD rig. Literature review. Method development training. Preliminary experiments on an existing rig.

11. Future work Glycerol stress experiments on existing reactor. Glycerol stress experiments on new rig. Publishing of literature review. Use of different Co-digestion wastes. Analysis of communities.

12. Summary Monitoring operational parameters is not sufficient to understand the process. Molecular techniques will be used. Ecological parameters of stability will be used to understand the influence of community structure on performance. A new rig has been constructed for the work and preliminary trials are ongoing. Future work will consider varying waste streams for Co- digestion.

13. Acknowledgments Thank you to EPSRC and QUESTOR for supporting this research work

14. References Fernandez A, Huang S, Seston S, Xing J, Hickey R, Criddle C, Tiedje J. 1999. How stable is stable? Function versus community composition. APPLIED AND ENVIRONMENTAL MICROBIOLOGY 65(8):3697-3697. Neubert MG, Caswell H. 1997. Alternative to resilience for measuring the responses of ecological systems to perturbations. Ecology 78(3):653-665.