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

The effect of different chemicals (H
₂
SO
₄
, NaOH and H
₂
O
₂
) pretreatments at various concentrations and microwave-assisted chemical (NaOH, H
₂
SO
₄
+ NaOH and H
₂
SO
₄
+ NaOH + H
₂
O
₂
) pretreatments on conversion of lignocelluloses in kitchen waste for maximum glucose yield were comparatively investigated. Overall, pretreatment by dilute H
₂
SO
₄
(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, H
₂
O
₂
pretreatment seems to have little effect on the glucose yield (1.53-3.05 /L) when the concentration of H
₂
O
₂
was increased. But when this oxidizing agent was added to H
₂
SO
₄
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.