The effect of physicochemical and enzymatic pretreatment on biohydrogen production by dark fermentation from Miscanthus giganteus

In this study, biohydrogen production from biomass was investigated using Miscanthus giganteus. The biomass were hydrolysed without using chemicals by autoclave at 121 and 135°C for 60 min. Chemical prehydrolysis were conducted by using weakly acidic 0.5 % and 1% sulfuric acid, weakly basic 0.5% and 1% NaOH chemical applications at 121 and 135°C for 60 min. The Viscoamyl Flow cellulose enzyme used for biological pretreatment after chemical pretreatment of biomass. In the pre-hydrolysis studies shows that, acidic and enzymatic hydrolysis combination was suitable for biomass hydrolysis. 27.43 g of reducing sugar was obtained under acidic 1 % H2SO4, 135°C degrees for 60 minutes and enzymatic pretreatment conditions. But 18.67 g of reducing sugar was obtained basic and enzymatic pretreatment conditions. Effect of pretreatment techniques on biohydrogen production was determined and 15.45 L biohydrogen was obtained from acidic pretreatment and 14.74 L biohydrogen was obtained from basic pretreatment of biomass. The effect of the initial pH on the biohydrogen production were determined at pH 6.5 and 5.5 and maksimum biohydrogen production was obtained at pH 5.5 as 17.16 L biohydrogen but biohydrogen production was decreased initial pH increase 6.5 maksimum biohydrogen production was obtained as 17.16 L at pH 6.5. In this study, 17.16 L biohydrogen was produced from 50 g reducing sugar hydrolysate at pH 5.5 and the ratio increased to 25.3L when increasing to 100g reducing sugar. But biohydrogen production yield was decreased increasing of the hydrolysate concentrations. The increasing in the sugar ratio was a suppressing effect on biohydrogen production for this reason yield of the biohydrogen was decreased. Miscanthus giganteus biomass is an important energy plant. It may be use for the production of biohydrogen and alternative renewable bioenergy products after the chemical, physical and biological pretreatment. Key words: Biohydrogen, Miscanthus giganteus, Dark fermentation, Enzymatic hydrolysis