biogas yield from dierent co-substrates such as 30 goat manure:70 corn stalks, 70 goat manure:30 corn stalks, 30 Goat manure:70 rice straw and 50 Goat manure:50 rice straw (Zhang et al. 2013), while the highest methane yield was produced from food waste co-digested with cattle manure. Furthermore, the highest quality and quantity of bio-manure