Abstract

Volatile fatty acids (VFAs) supplementation in ruminants' diet as a source of energy and chemical precursors and their effect on animal's physiology and well-being has long been of scientific interest. Production of VFAs through anaerobic digestion of agro-industrial residues not only creates value but also presents an alternative sustainable approach for ruminant feed supplementation. Therefore, this study aimed to investigate the bioconversion of agro-industrial residues produced in large quantities such as apple pomace (AP), thin stillage (Ts), and potato protein liquor (PPL) to VFAs, fully complying to regulations set for ruminant feed supplement production. In this regard, batch acidogenic fermentation assays (pH 6-10) and semi-continuous immersed membrane bioreactor (iMBR) were applied. In batch assays, at pH 10 the co-digestion of Ts and PPL produced the highest VFAs concentration (14.2 g/L), indicating a yield of 0.85 g CODVFAs/g volatile solids (VS)added. The optimum batch condition was then applied in the iMBR for in situ fermentation and recovery of VFAs at different organic loading rates (OLR). With increasing the OLR to 3.7 gVS/L.day, the highest VFAs concentration of 28.6 g/L (1,2 g CODVFAs /gVSadded) was achieved. Successful long-term (114 days) membrane filtration was conducted in a media with a maximum of 40 g/L of total solids (TS), facing irreversible membrane fouling in the final stages. Acidogenic fermentation using an iMBR has the potential to play an important role in the future of feed additive provision through the biorefining of agro-industrial wastes via the carboxylate platform, given the role of VFAs production from organic residues.

Keywords

Agro-industrial residues; Anaerobic digestion; Volatile fatty acids; Ruminant feed; Membrane bioreactor

Published in

Waste Management
2023, Volume: 170, pages: 62-74

SLU Authors

• Rustas, Bengt-Ove

  • Department of Applied Animal Science and Welfare, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

End hunger, achieve food security and improved nutrition and promote sustainable agriculture
Ensure sustainable consumption and production patterns


UKÄ Subject classification

Animal and Dairy Science


Publication identifier

DOI: https://doi.org/10.1016/j.wasman.2023.07.032

Permanent link to this page (URI)

https://res.slu.se/id/publ/123461