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Renewable energy - evaluation of low energy demand pre-treatments to optimise methane production from microalgae

Lookup NU author(s): Dr Yanghanzi ZhangORCiD, Dr Gary Caldwell, Dr Paul Sallis



This is the authors' accepted manuscript of an article that has been published in its final definitive form by Institution of Engineering and Technology, 2019.

For re-use rights please refer to the publisher's terms and conditions.


Anaerobic digestion (AD) of microalgae is a sustainable process to produce methane-rich biogas for bioenergy production. However, the rigid cell walls of microalgae protect them against attack from hydrolytic bacteria, and consequently prevent efficient biodegradability and lower methane production. In this study, the effects of low energy demand enzymatic and low-temperature thermo-alkaline pre-treatments on microalgae AD were investigated in batch biochemical methane potential (BMP) tests. The results found that methane yields were significantly enhanced by both pre-treatments. Methane yields were enhanced the most for the microalgae Chlorella vulgaris (by 22–162%) following enzymatic pre-treatment, whilst thermo-alkaline pre-treated C. vulgaris improved methane yields by 4–26%. In enzymatic pre-treatment, C. vulgaris pre-treated with enzymes mixtures showed higher methane yields compared to single enzymes. In low-temperature thermo-alkaline pre-treatment, the level of methane yield enhancement depended on alkaline dosage and pre-treatment temperature, but the high alkaline dosages were associated with limitations such as a prolonged lag phase in the digestion process. From an energy viewpoint, both pre-treatments showed positive energy balances for the majority of experimental conditions, and therefore both pre-treatments are considered to be energetically efficient methods to pre-treat microalgae for methane production via AD.

Publication metadata

Author(s): Zhang Y, Caldwell GS, Sallis PJ

Publication type: Article

Publication status: Published

Journal: IET Renewable Power Generation

Year: 2019

Volume: 13

Issue: 10

Pages: 1701-1710

Print publication date: 11/07/2019

Online publication date: 11/04/2019

Acceptance date: 09/04/2019

Date deposited: 12/04/2019

ISSN (print): 1752-1416

ISSN (electronic): 1752-1424

Publisher: Institution of Engineering and Technology


DOI: 10.1049/iet-rpg.2018.6080


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