Fermentative volatile fatty acid production and recovery from grass using a novel combination of solids separation, pervaporation, and electrodialysis technologies

A novel combination of solids screening, centrifugation, microfiltration, pervaporation, and electrodialysis were used for the targeted and exclusive recovery of volatile fatty acids (VFAs) from an 80 L bioreactor. The bioreactor was continually-fed with grass waste, containing 40 g L-1 total solids, over three, seven-day, hydraulic retention times. A VFA solution with a concentration up to 4,500 mg L-1 was recovered. VFA yields were also increased from 707 to 875 mg of VFA per gram of volatile solids by alleviating end-product inhibition. Both these accomplishments are significant step-changes in adding value to waste, and increased substrate utilisation rates will be attractive from a waste remediation perspective.

Automated summary

A novel combination of technologies was used to recover VFAs from a bioreactor, significantly increasing VFA yields and addressing end-product inhibition. These achievements represent important breakthroughs in adding value to waste and increasing substrate utilization rates.