| This study focused on the optimization of the enzymatic hydrolysis of three feedstocks: crop residues, poultry manure, and sewage sludge. The crop residues investigated include corn stalk and bagasse, they were pre-treated with KOH prior to enzymatic hydrolysis. At 40°C, with an enzyme loading of 800 units/g substrate, the glucose yields from enzymatic hydrolysis of corn stalk and bagasse were 65.4 +/- 2.3% and 51.1 +/- 2.3%, respectively. The enzymatic hydrolysis of corn stalk was further optimized by using wet substrate, which was ground before KOH treatment, and by adding half of the enzyme dosage at the beginning and half in the middle of the hydrolysis instead of adding the entire dosage at the beginning.; For poultry manure, the highest glucose conversion was achieved when it was treated with KOH and then dried and ground prior to enzymatic hydrolysis. At 40°C, enzyme loading 400 units/g substrate, the conversion was 27.6 +/- 1.2%. Under the same optimum conditions as crop residues, 31.1 +/- 2.7% of wet raw sludge was converted to glucose, and it was increased to 54.2 +/- 4.0% when HCl and KOH pre-treatments were employed.; An integrated ethanol production process was proposed and cost analysis was performed for each feedstock. The operational cost to produce one litre of ethanol was estimated to be {dollar}4.97, {dollar}5.26 and {dollar}4.27 for corn stalk, poultry manure, and raw sludge respectively. |
