include degraded compounds i.e. pro

include degraded compounds i.e. protein 12.5% weight dry base, cellulose 31% weight dry base, starch 12.5%
weight dry base, and hemicellulose 12% weight dry base [15], and the minimum retention time in biogas production
approximately of 10-15 days [16]. By using Equation 1-6, there are obtained the rate of cow manure to be fed to
digester as much as 534919.4 gram per day (534.9194 kg per day) and the digester volume of 16.7162 m3 when the
safety factor is 0.25 or 25%. Due to the conversion factor used in the previous research about 60% [1], it is obtained
the solid fertilizer from the digester sludge approximately of 64917.82 gram per day or 64.9178 kg per day.
Based on the manure production from a typical 1,400 pound (700 kg) foreign milk cow as much as 112 pound (56
kg) [15], the amount of cow to produce the said manure is 9.5521 or it is needed at least 10 cow to generate the
electricity power. However, in case in Indonesia that the cow is smaller and the manure produced is less, more cow
have to be maintained to generate the amount of power. For example, if one cow only producing 10-30 kg manure a
day, the minimum amount of cow needed will be 18-54. Amount of manure needed, amount of cow to produce the
manure, and digester volume resulted from the calculation can be seen in Table 1.