Immersed ozonation of agro-wastes as an effective pretreatment method in bioethanol production

Lignocellulosic-based ethanol is a viable alternative to corn-based ethanol. However, the use of such feedstock is more complex than the use of sugar or starch due to the necessity for a pretreatment stage. Here we tested three pretreatment processes of oat straw: (1) submerged ozonation in water, (2) low temperature (40 °C) diluted sulphuric acid (DSA) and (3) room temperature diluted sulphuric acid/ozone mixture (SOM). A unique water/ozone reactor was designed and constructed to demonstrate the pretreatment processes. Results showed best lignin removal by the submerged ozonation pretreatment and consequently the highest sugar and ethanol yields. Despite the non-conventional low temperature, DSA pretreatment results had showed slight lower yields then ozonation, with degradation of hemicellulose to xylose, while SOM pretreatment showed the poorest results. DSA pretreatment would probably show industrial feasibility when pentoses fermenting abilities will be added.