Arisht S.N.Mahmod S.S.Abdul P.M.Indera Lutfi A.A.Takriff M.S.Lay C.H.Silvamany H.Sittijunda S.Jahim J.M.Mahidol University2023-06-182023-06-182022-11-01Journal of Environmental Management Vol.321 (2022)03014797https://repository.li.mahidol.ac.th/handle/20.500.14594/84669Biological hydrogen production using palm oil mill effluent (POME) as a carbon source through dark fermentation process has been suggested to be a promising bioenergy potential and enacts as alternative renewable energy source. Results have indicated that among various 1.5% (w/v) chemical pre-treatments (sodium hydroxide, NaOH; hydrochloric acid, HCl; sulphuric acid, H2SO4; phosphoric acid, H3PO4 and nitric acid, HNO3) on POME, using H3PO4 would generate maximum biohydrogen production of 0.193 mmol/L/h, which corresponded to a yield of 1.51 mol H2/mol TCconsumed with an initial total soluble carbohydrate concentration of 23.52 g/L. Among H3PO4 concentrations (1%–10%), the soluble carbohydrate content and the biohydrogen produced was highest and increased by 1.70-fold and 2.35-fold respectively at 2.5% (w/v), as compared to untreated POME. The batch fermentation maximum hydrogen production rate and yield of 0.208 mmol/L/h and 1.69 mol H2/mol TCconsumed were achieved at optimum pre-treatment conditions of pH 5.5 and thermophilic temperature (60 °C). This study suggests that chemical pre-treatment approaches manage to produce and improve the carbohydrate utilisation process further. Continuous fermentation in CSTR at the optimum conditions produce heightened 1.5-fold biohydrogen yield for 2.5% H3PO4 at 6 h HRT as compared to batch scale. Bacterial community via next-generation sequencing analysis at optimum HRT (6 h) revealed that Thermoanaerobacterium thermosaccharolyticum registered the highest relative frequency of 20.24%. At the class level, Clostridia, Bacilli, Bacteroidia, Thermoanaerobacteria, and Gammaproteobacteria were identified as the biohydrogen-producing bacteria in the continuous system. Insightful findings from this study suggest the substantial practical utility of dilute chemical pre-treatment in improving biohydrogen production.Environmental ScienceArticleSCOPUS10.1016/j.jenvman.2022.1158922-s2.0-851361003871095863035988402