The main shortcoming of human excreta is the low ratio C/N which about 6-10. It is lower than the ratio of C/N
that is expected on biogas production by 25-30. This means that the amount of nitrogen is greater than the amount of carbon, which resulted in a lot of ammonia formation from the decomposition process and further improves the
system pH becomes alkaline. To overcome this shortcoming, the addition of high C/N ratio raw material is needed
such as rice straw (C/N ratio 12.5-25), rice husk (C/N ratio 100-125), or corncob (C/N ratio 50) [12]. Other problem
in using human excreta to produce biogas is the E. coli content in the waste to be disposal into the environment.
However, Pramond and Michelle, 2011 [13] from their research showed that the percentage of survival colonies
decreases with the length of time of incubation, as shown in Fig. 4. They also found that At thermophilic
temperature, E. coli inactivation and biogas production were faster than that of at moderate and mesophilic
temperatures.