Improving the bioenergy production from wheat straw with alkaline pretreatment

A pretreatment process for wheat straw using potassium hydroxide (KOH) and recycled black liquor as a treatment reagent was developed and the minimum fresh chemical and water requirement were determined. Black liquor recycling in the pretreatment process resulted in a 75% reduction in fresh water use and 25% in KOH use, when compared to no recycling. It was found that after five batches of treatment, the concentrations of reducing sugar, chemical oxygen demand (COD), and K+ in black liquor, reached stable levels. During the pretreatment with black liquor recycling, 32-35% lignin was reduced in wheat straw. The pretreated straw showed reducing sugar yield of 336-366 mg g(-1) [total solid (TS)] and methane yield of 290-303 mg g(-1) [volatile solid (VS)] when subjected to enzymatic hydrolysis and anaerobic digestion, respectively. (C) 2015 IAgrE. Published by Elsevier Ltd. All rights reserved.