Simple and Combined Pretreatment of a Mixture of Forestry and Aromatic-Medicinal Plant Waste by Chemical, Physical and Enzymatic Methods

Abstract

Forestry waste (FW) extracted parts of medicinal-aromatic plant waste (EPW) and unused parts (UPW) are considered potential resources for energy recovery (their heating value of approximately 19 MJ/kg). In order to valorize lignocellulosic biomass, a pretreatment process is required to hydrolyze the recalcitrant lignocellulosic complex into fermentable simple sugars. The aim of this study is to determine the best method of pretreatment that takes into account treatment time, efficiency, and environmental friendliness. The mixture of FW, EPW, and UPW was treated by simple and combined treatment using different methods like acid sulfuric (Ac), steam explosion (SE), and enzymatic (E) (cellulase and hemicellulase). The results showed that the combined and simple Ac treatments are the most efficient compared with SE and E treatments in the hydrolysis of polysaccharide of cellulose with a rate respectively of 90,5% and 77,6% and hemicellulose with a rate respectively of 80,63% and 87,14%. In addition, both of the preceding methods release an important rate of total phenolic compounds. Combined treatment demands high time but is friendly(approximately 1 day), and Ac treatment is less time-consuming(about 25 min) but harmful to the environment and causes the corrosion of equipment. In conclusion, combined treatment can be the best method and the high time required can be reduced with the progress of the research.

Keywords

• pretreatment
• cellulose
• biomass
• lignocellulosic complex
• plant waste