**4.2 Factors affect biogas production**

Production of biogas involves a series of four complex biochemical processes (hydrolysis, acidogenesis, acetogenesis, and methanogenesis) depending upon different factors such as type of substrates, substrate particle size, temperature range, pH, carbon/nitrogen (C/N) ratio, and inoculums concentration [62, 96–99]. There are various factors affecting biogas production from anaerobic digestion. Some of the key factors have been elaborated in detail below.
