Membrane bioreactor assisted volatile fatty acids production from agro-industrial residues for ruminant feed application

Milad Parchami; Clarisse Uwineza; Onyinyechi H Ibeabuchi; Bengt-Ove Rustas; Mohammad J Taherzadeh; Amir Mahboubi

doi:10.1016/j.wasman.2023.07.032

Membrane bioreactor assisted volatile fatty acids production from agro-industrial residues for ruminant feed application

Waste Manag. 2023 Oct 1:170:62-74. doi: 10.1016/j.wasman.2023.07.032. Epub 2023 Aug 5.

Authors

Milad Parchami¹, Clarisse Uwineza¹, Onyinyechi H Ibeabuchi¹, Bengt-Ove Rustas², Mohammad J Taherzadeh¹, Amir Mahboubi³

Affiliations

¹ Swedish Centre for Resource Recovery, University of Borås, 501 90 Borås, Sweden.
² Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Box 7024, Uppsala, Sweden.
³ Swedish Centre for Resource Recovery, University of Borås, 501 90 Borås, Sweden. Electronic address: amir.mahboubi_soufiani@hb.se.

PMID: 37549528
DOI: 10.1016/j.wasman.2023.07.032

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 COD_VFAs/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 COD_VFAs /gVS_added) 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; Membrane bioreactor; Ruminant feed; Volatile fatty acids.