Comparison of pretreatment methods for the enhancement of fermentable sugar production from kitchen waste

The effect of different chemicals (H2SO4, NaOH and H2O2) pretreatments at various concentrations and microwave-assisted chemical (NaOH, H2SO4 + NaOH and H2SO4 + NaOH + H2O2) pretreatments on conversion of lignocelluloses in kitchen waste for maximum glucose yield were comparatively investigated. Overall, pretreatment by dilute H2SO4 (2%) achieved the highest glucose yield of 39.43 g/L with glucose recovery of 98.86%. Alkali pretreatment using NaOH at different concentration shows no significant effect on the glucose generation (0.61–1.13 g/L) when NaOH concentration was increased. However, the combination of alkali pretreatment with microwave treatment resulted in a drastic increase of glucose yield in kitchen waste sample. Meanwhile, H2O2 pretreatment seems to have little effect on the glucose yield (1.53–3.05 /L) when the concentration of H2O2 was increased. But when this oxidizing agent was added to H2SO4 and NaOH -microwave treatment, it increases the glucose yield from 10.36 to 13.31 g/L. With respect to glucose recovery, all microwave-assisted chemical pretreatment achieved the value of more than 90% glucose recovery.