**3.1 Mechanical treatment**

Major mechanical treatment includes chiping, grinding and milling to reduce the particle size which is responsible to increase surface area and increased surface area responsible for better interaction between substrate and enzyme [21, 35]. Physical treatment includes un-catalyzed steam explosion, hot water pretreatment and high energy radiations. By the process size reduces to 10–30 mm after chipping the biomass and finally after milling or grinding 0.2–2 mm size is attained.
