Production of volatile fatty acids from agro-food residues for ruminant feed inclusion using pilot-scale membrane bioreactor

The transition from laboratory scale production to industrial scale implementation is a critical step in introducing innovative technologies into the industry. Pilot-scale studies play a pivotal role in ensuring a smooth transition with minimal risks. This study investigates the scalability of a pilot-scale submerged membrane bioreactor (MBR) to produce volatile fatty acids (VFAs) as a sustainable alternative feed ingredient for ruminants. Building upon previous laboratory-scale research, this study aims to validate the scalability and replicability of the technology, ensuring that the results obtained at a smaller scale can be consistently achieved at a larger scale. Through the acidogenic fermentation of potato protein liquor (PPL) and apple pomace (AP) inoculated with rumen microorganisms, VFAs have been produced, and recovered over 105 days. Strategic adjustments to the organic loading rate (OLR, 2 gVS/L.day) achieved high and stable total VFAs concentration (above 10 g/L) with average VFAs yield of 0.47 gVFAs/gVS added by effectively inhibiting methanogenesis. The favorable characteristics of the VFAs effluent, including its pH, VFAs distribution (high acetic and caproic acids), and ammonium content (around 400 mg/L), suggest its potential as a sustainable feed ingredient for ruminants. Further research is necessary to explore the precise effects and optimal utilization of VFAs as a feed supplement, but this study presents a promising step towards sustainable VFAs production and its application in the livestock sector. • The scale up of VFAs production from co-digetion of AP and PPL was successfully conducted for 105 days. • Highest VFA concentration was found at OLR 2 gVS/L.day of AP ad PPL co-digestion. • TSS accumulation in the reactor controlled by increasing the HRT to 20 days. • The maximum VFA yield was obtained at OLR2 period (0.61 gVFA/gVS added ). • Pilot MBR shows great potential to be introduced in industrial animal feed manufacturing.