Increasing the efficiency of dry anaerobic digestion via anaerobic gut fungi bioaugmentation: an exploratory study
- Project lead
- Jolanda van Munster
- Institute
- SRUC
Summary
Around 700 million tonnes of rice straw is produced annually as a by-product of rice cultivation in Asia, and over 300 million tonnes is routinely burned in the open fields. The resulting release of high levels of pollutants and greenhouse gases negatively impacts both health of the local population and the environment. A promising alternative solution is to convert this agricultural waste to biogas (methane and carbon dioxide) via anaerobic digestion.
In this project, a new partnership will be formed between Scotland’s Rural College (SRUC) and Qube Renewables, that brings together experts in anaerobe fungal biology with developers of a novel, low-cost dry anaerobic digestion (AD) system for processing rice straw and other agricultural wastes. Together they will test feasibility and effectivity of applying anaerobic fungi in biogas production from rice straw. Findings from the project will enable optimisation of the developed anaerobic digestion system and accelerate implementation of the system to aid conversion of rice straw waste to biofuel.
Aims
Rice straw is an abundant agricultural waste product which has high potential for use as feedstock for anaerobic digestion. This project combines QUBE’s dryQUBE anaerobic digestors with SRUC’s expertise in anaerobic fungi that are efficient in plant fibre degradation, to test the use fungi to increase efficiency of biogas production in a novel type of anaerobic digester.
Outcomes
Initially basic parameters were established for the growth of two different species of anaerobic gut fungi, Caecomyces communis and Neocallimastix frontalis, on rice straw, exploring growth temperature, media composition and lignocellulose feedstock particle size and solid loadings. In vitro augmentation of bioreactor leachate with the anaerobic fungi demonstrated limited but positive effects of augmentation, but after scale-up to an experimental version of the dryQUBE system, fungal survival seemed to be limited, and beneficial effects of augmentation were not observed. This indicates that other strategies to enable fungal augmentation of the digestor may need to be explored.
Impact
The project has solidified the partnership between Qube Renewables and SRUC and will result in a scientific publication describing the obtained results. Further exploration of other methods for AGF augmentation in anaerobic digestion are planned.
Academic partner: Jolanda van Munster, SRUC
Industrial partner: Joanna Clayton, Qube Renewables Ltd
