Comparison of acid and alkaline pretreatment methods for the bioethanol production from kitchen waste

Abstract

This study was aimed at optimizing the effect of thermochemical pretreatment methods used independently or in combination to maximize the production of fermentable soluble sugars from kitchen waste. The waste was treated with hydrochloric acid (HCl) and sodium hydroxide (NaOH) solutions (in 0–5% concentrations) to convert organic material into fermentable sugars at elevated temperatures. The acid and alkaline pretreatments were compared in terms of the percentages of glucose recovery and the yields of total soluble sugars. According to our results, the glucose percentage and indirectly the glucose concentration were increased by acid or alkaline pretreatment. HCl and NaOH pretreatment at increasing temperatures increased the glucose yield from kitchen waste in comparison with untreated organic material. Our results showed that chemical pretreatment of kitchen waste, using both 1% HCl for 90 min (at 60 °C) and 3% NaOH for 90 min (at 30 °C), increased the soluble sugar concentrations by 95% and 35%, respectively, in comparison with untreated kitchen waste.