Assessing Different Inoculum Treatments for Improved Production of Hydrogen through Dark Fermentation

Saleh Al-Haddad (), Cynthia Kusin Okoro-Shekwaga, Louise Fletcher, Andrew Ross and Miller Alonso Camargo-Valero ()
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Saleh Al-Haddad: BioResource Systems Research Group, School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK
Cynthia Kusin Okoro-Shekwaga: BioResource Systems Research Group, School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK
Louise Fletcher: BioResource Systems Research Group, School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK
Andrew Ross: School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, UK
Miller Alonso Camargo-Valero: BioResource Systems Research Group, School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK

Energies, 2023, vol. 16, issue 3, 1-15

Abstract: Hydrogen gas (H 2 ) is an energy carrier that does not generate carbon dioxide emissions during combustion, but several processes in use for its production demand high energy inputs associated with fossil fuels and greenhouse emissions. Biological processes, such as dark fermentation (DF), have the potential to remove the dependency on fossil fuels in H 2 production. DF is a process that encourages fermentative bacteria to ferment organic substrates to produce H 2 as a truly clean energy carrier, but its success depends on removing the presence of competing H 2− consuming microorganisms in the inoculum consortia. This paper addresses a strategy to enhance H 2 production from different types of substrates by testing inoculum pre-treatment processes to inactivate H 2− consuming bacteria, including acid-shock (pH 3), basic-shock (pH 10) and heat-shock (115 °C) methods. Digestate from anaerobic digesters processing sewage sludge was used to produce pre-treated inocula, which were subsequently tested in a batch bio-H 2 potential (BHP) test using glucose as a substrate. The results show that heat-shock pre-treatment was the best method, reporting a H 2 yield of 191.8 mL-H 2 /gVS added (the untreated inoculum reported 170.91 mL-H 2 /gVS added). Glucose conversion data show a high concentration of butyric acid in both treated and untreated inocula during BHP tests, which indicate that the butyrate pathway for H 2 production was dominant; shifting this to the formate route could further enhance net H 2 production. A standardised inoculum-conditioning method can help to consistently assess the biohydrogen potential of suitable feedstock for DF and maximise H 2 yields.

Keywords: biohydrogen production; clean energy carrier; dark fermentation; inoculum pre-treatment (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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