Upcycling anaerobic digestion streams into feed-grade protein for increased environmental sustainability

Hadis Marami, Sahar Khademi, Shahin Rafiee, Hossein Mobli, Morten Birkved, He Li, Irini Angelidaki and Benyamin Khoshnevisan

Renewable and Sustainable Energy Reviews, 2025, vol. 216, issue C

Abstract: Biogas plants have long been recognized as well-established systems for converting waste into energy and organic fertilizers. However, biogas plants are expected to go beyond their primary functions to enhance the sustainability gains from the circular bioeconomy. Carbon (CO2 and CH4) and nitrogen streams from anaerobic digestion (AD) facilities can be converted into higher-value products, such as microbial proteins (MPs). While two dominant pathways are known for MP production from AD streams, namely methane-oxidizing bacteria (MOB) and hydrogen-oxidizing bacteria (HOB), there is a lack of comprehensive research comparing these two pathways from an environmental sustainability viewpoint. Furthermore, the extent to which the environmental sustainability of MP production platforms depends on feedstock characteristics is yet to be scrutinized. To address the above-mentioned research questions, four biogas plants treating different types of biowaste were selected as case studies. Specifically, the effects of the C/N ratio in the input streams, biogas upgrading technologies (water scrubbing and biological biogas upgrading), and microbial platforms (HOB and MOB) were investigated. Environmental impacts were assessed using consequential life cycle assessment (CLCA), with Denmark as the spatial boundary and 2030 as the temporal boundary. Across all scenarios, the MOB pathway demonstrated superior environmental performance compared with the other pathways. Furthermore, the composition of the feedstock and quantity of biogas play key roles in the total environmental gains. Finally, the sources of uncertainty and opportunities for future improvements are identified to pave the way for land-independent feed-grade protein production using locally available biowastes.

Keywords: Anaerobic digestion; Microbial protein; Single cell protein; Circular economy; Sustainability; Methane-oxidizing bacteria; Hydrogen-oxidizing bacteria (search for similar items in EconPapers)
Date: 2025
References: Add references at CitEc
Citations:

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S1364032125003119
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:rensus:v:216:y:2025:i:c:s1364032125003119

Ordering information: This journal article can be ordered from
http://www.elsevier.com/wps/find/journaldescription.cws_home/600126/bibliographic
http://www.elsevier. ... 600126/bibliographic

DOI: 10.1016/j.rser.2025.115638

Access Statistics for this article

Renewable and Sustainable Energy Reviews is currently edited by L. Kazmerski

More articles in Renewable and Sustainable Energy Reviews from Elsevier
Bibliographic data for series maintained by Catherine Liu ().