Recovery and enhanced yields of volatile fatty acids from a grass fermentation via in-situ solids separation and electrodialysis

An industrially applicable methodology utilising a novel combination of filtration and electrochemical separation technologies was successfully used to recover, and enhance the production of, volatile fatty acids from an 82.5 L bioreactor, continually fed with grass at 5% total solids. Volatile fatty acid yields were increased from 287 to 404 mg_vfa g_vs⁻¹ and concentrated up to 4800 mg L⁻¹ in a solution suitable for downstream conversion to platform chemicals. This work also shows that there is considerable headroom to increase further volatile fatty acid recovery rates and yields by increasing the capacity of the recovery methodology. The novel methodology developed herein could help to address some of the environmental and economic concerns that have led to the need to diversify the ways in which grass is used as a resource, and represents an alternative to petrochemicals as a carbon source for platform chemical production.