3.3. Mechanical scheme
Substrate size also matter in biogas production. Smaller the size
of the substrate, higher will be the rate of bacterial activity and
hence rapid production of biogas. On the other hand larger sized
substrate also leads digester blockage [46]. Smaller substrate size
can be achieved by milling which will convert larger substrate to
smaller pieces. Mechanical pretreatment diminishes digestion
time by 23–59% mostly [43]. Ultrasonic pretreatment for 30 min increases methane production by 64% [46]