Effect of pH, temperature and agitation on thermophilic biohydrogen production using immobilized cells on carbon composites (GAC-NiFe3O4)

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-04, Vol.485, p.149980, Article 149980
• Main Authors: Mohd Jamaludin, Nina Farhana, Engliman, Nurul Sakinah, Abdul Manaf, Shareena Fairuz, Idrus, Syazwani, Abdullah, Luqman Chuah, Jamali, Nur Syakina
• Format: Article
• Language: English
• Subjects: Dark fermentation; Granular activated carbon nanocomposites; Immobilized cell; Process parameter; Thermophilic biohydrogen production
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.149980

[Display omitted] •Agitation impacts biohydrogen production more than pH and temperature.•Agitation yielded the highest yield at 3.44 ± 0.54 mol H2/mol sugar.•Gompertz equation to estimate parameters related to biohydrogen production.•Holm-Bonferroni method to establish reliability and significance of results.•Thermoanaerobacterium emerged as the dominant genus in biohydrogen production. Carbon composites-immobilized cell was utilized to enhance biohydrogen production. The initial pH, temperature and agitation effect was studied using the one-factor-at-a-time (OFAT) method. The optimal initial pH obtained was at pH 6.0 with hydrogen yield (HY) of 2.66 ± 0.09 mol H2/mol sugar, correlating with Gompertz constant of Hm = 974.99 mL, Rm = 17.90 mL/h and λ = 1.70 h. At 60 °C, the highest HY was obtained at 2.75 ± 0.11 mol H2/mol sugar. These corresponded to the Gompertz constant of Hm = 934.58 mL, Rm = 18.78 mL/h and λ = 1.89 h. The optimal agitation obtained was at 120 rpm, attaining the highest HY of 3.44 ± 0.54 mol H2/mol sugar, corresponding to the Gompertz constant of Hm = 1054.86 mL, Rm = 24.37 mL/h and λ = 3.90 h. The rRNA sequencing result revealed that the predominant species in the study was Thermoanaerobacterium. This study provides critical insight into process control conditions on biohydrogen production.