Effect of alkali, acid and thermal pretreatment techniques on biohydrogen production from organic fraction of municipal solid waste

With the rising need for sustainable energy solutions and efficient waste management, converting organic waste into biohydrogen offers a dual benefit. This study explores the potential of the Organic Fraction of Municipal Solid Waste for hydrogen production, applying thermal, acid, and alkali pretreatment techniques to enhance substrate digestibility. Prior to the application of these techniques, a heat-shock pretreatment was employed on the anaerobic inoculum to suppress hydrogen-consuming microbes and favour hydrogenogenic activity. Among the strategies tested, alkali (followed by acid and thermal) pretreatment resulted in significant improvement in substrate solubilization, with the highest sCOD and volatile solids reduction. In Biochemical Hydrogen Potential assays, it yielded a peak value of about 190 mL H₂/g VS, nearly six times higher than the untreated control. GC-TCD analysis revealed rapid hydrogen evolution within the first 24 hours, while VFA profiling indicated acetic acid dominance, a known precursor for hydrogen production. These findings suggest that alkaline pretreatment combined with inoculum conditioning is a promising route for maximising hydrogen yields.