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Co-digestion of microalgae with potato processing waste and glycerol: Effect of glycerol addition on methane production and the microbial community

Lookup NU author(s): Dr Yanghanzi ZhangORCiD, Dr Gary Caldwell, Professor Phil BlytheORCiD, Dr Andrew Zealand, Dr Shuo LiORCiD, Simon Edwards, Dr Jin XingORCiD, Dr Paul Goodman, Dr Paul Whitworth, Dr Paul Sallis



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© The Royal Society of Chemistry.The production of methane-rich biogas from the anaerobic digestion (AD) of microalgae is limited by an unfavorable biomass carbon-to-nitrogen (C/N) ratio; however, this may be ameliorated using a co-digestion strategy with carbon-rich feedstocks. For reliable plant operation, and to improve the economics of the process, secure co-feedstock supply (ideally as a waste-stream) is important. To this end, this study investigated the feasibility of co-digesting microalgae (Chlorella vulgaris) with potato processing waste (potato discarded parts, PPWdp; potato peel, PPWp) and glycerol, while monitoring the response of the methanogenic community. In this semi-continuous study, glycerol (1 and 2% v/v) added to mixtures of C. vulgaris : PPWdp enhanced the specific methane yields the most, by 53-128%, whilst co-digestion with mixtures of C. vulgaris : PPWp enhanced the methane yields by 62-74%. The microbial communities diverged markedly over operational time, and to a lesser extent in response to glycerol addition. The acetoclast Methanosaeta was abundant in all treatments but was replaced by Methanosarcina in the potato peel with glycerol treatment due to volatile fatty acid (VFA) accumulation. Our findings demonstrate that the performance of microalgae co-digestion is substantially improved by the addition of glycerol as an additional co-feedstock. This should improve the economic case for anaerobically digesting microalgae as part of wastewater treatment processes and/or the terminal step of a microalgae biorefinery.

Publication metadata

Author(s): Zhang Y, Caldwell GS, Blythe PT, Zealand AM, Li S, Edwards S, Xing J, Goodman P, Whitworth P, Sallis PJ

Publication type: Article

Publication status: Published

Journal: RSC Advances

Year: 2020

Volume: 10

Issue: 61

Pages: 37391-37408

Online publication date: 09/10/2020

Acceptance date: 28/09/2020

Date deposited: 05/11/2020

ISSN (electronic): 2046-2069

Publisher: Royal Society of Chemistry


DOI: 10.1039/d0ra07840a


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