Institute for Sustainability

Improving anaerobic digestion

Improving Anaerobic Digestion

Using computer models to improve anaerobic digestion

This project led by Dr Matthew Wade, School of Civil Engineering and Geosciences, focused on understanding the complex interactions between microorganisms in anaerobic digestion to find ways to improve it in the UK. The relationships between different microorganisms in an anaerobic digester are important for producing biogas.

There can be up to 100 or even 1000 different species of microbes in a digester. Most models only account for two species while Matthew's model uses a maximum of five or six. He explains some of the findings and the importance of the research for industry and future energy production.

What was the focus of the research?

The research carried out within the EXPAND project was focused on modelling microbial communities using a mechanistic understanding of the interactions between two or more organisms in a process. The system investigated by researchers was a simplified version of the anaerobic digestion process.

This process has received renewed interest in recent years within the UK due to the increased awareness of conventional energy constraints, and the need to tap into the potential of renewable energy sources, such as low-cost biomass to energy conversion. The project modelled the role of three organisms in a microbial community.

Why is it important?

Anaerobic processes are now a more economically viable option thanks to increased investment in research by UK government. The UK is now the second largest anaerobic digestion utilising nation in Europe. The model of a complex environment is closer to what actually happens inside of an anaerobic digester.

The advantage of computer modelling is that you can test different kinds of organisms and how they act in the digester so you don’t have to wait months or years to grow organisms. Researchers also looked at how anaerobic digestion could break down chlorophenol, which is used in pesticides and herbicides and is listed as a priority pollutant by the USEPA known to harm human and animal health.

Who could benefit?

The research is helpful for synthetic biologists working at engineering artificial communities of a small number of species, and for operators of anaerobic digesters interested in the dynamics of a real world system.

What was found?

  • The addition of hydrogen and/or phenol to anaerobic digestion helps maintain a viable population of all organisms under a wider operating range than the passive process.
  • The research provided an understanding of microbial processes beyond the ‘two species model’ as it looked at the interactions between three different species of microorganisms in anaerobic digestion.
  • The work highlighted the ability to use rigorous mathematical analysis to understand emergent properties of microbial ecological interactions, such as an unstable limit cycle where populations fluctuate rather than reach a fixed-stable state over time.
  • Modelling used in the research could one day be used to control anaerobic digestion to maximise production of biogas in a sustainable way that inhibits failure.

Publication

This research is from the project 'Exploring the global dynamics of anaerobic digestion processes', funded through our Responsive Mode Funding call.

Cockle Park Farm Anaerobic Digester