3.2. Chemical scheme
Pretreatment with acid causes biodegradation of organic substance
which will be easily converted to biogas by further degradation
through bacterial action. Lignocellulose substrate can also be degraded by using sodium hydroxide or calcium hydroxide. It is
beneficial for the formation of smaller molecular compounds. On
the other hand it degrades carbon which increases the formation
of carbon dioxide [43]. Biogas yield can be improved by combine
action of heat and alkaline [44]. The thermochemical pretreatment
with applied temperature of 147 °C and heating time of
25.3 min results in high methane production [45].