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Anaerobic co-digestion of microalgae Chlorella vulgaris and potato processing waste: Effect of mixing ratio, waste type and substrate to inoculum ratio

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

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Abstract

This investigation aimed to evaluate the feasibility of potato processing waste (PPW) as a co-substrate for Chlorella vulgaris in batch biochemical methane potential (BMP) tests. Three parameters were examined: C. vulgaris and PPW mixing ratios (100:0, 75:25, 50:50, 25:75 and 0:100), PPW type (potato discarded parts (PPW_dp) and potato peel (PPW_p)), and substrate to inoculum ratio (0.5 and 1.0 SIRs). The mixing ratio was a significant factor with higher methane yields obtained with 25:75 C. vulgaris: PPW. The type of PPW also affected methane yield, as C. vulgaris co-digested with PPW_dp increased methane yield by 22–47%, versus a 12–32% enhancement with PPW_p. Moreover, a SIR of 1.0 led to an accumulation of soluble COD, resulting in decreased methane yield relative to a SIR of 0.5. Overall, the current study showed that PPW are suitable feedstocks for co-digestion with microalgae, with the enhanced methane yields attributed to a balance C/N ratio. However, the extra nitrogen in the seed inoculum of the BMP test may have obscured the full benefits and hidden some synergistic effects. Therefore, the follow-up studies should be carried out in continuous anaerobic digesters to verify the full potential of PPW as co-digestion substrate for microalgae.

Publication metadata

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

Publication type: Article

Publication status: Published

Journal: Biochemical Engineering Journal

Year: 2019

Volume: 143

Pages: 91-100

Print publication date: 31/12/2018

Online publication date: 26/12/2018

Acceptance date: 25/12/2018

Date deposited: 03/01/2019

ISSN (print): 1369-703X

Publisher: Elsevier

URL: https://doi.org/10.1016/j.bej.2018.12.021

DOI: 10.1016/j.bej.2018.12.021

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