2.5. Analytical procedures
Biogas production rate, methane concentration, and slurry samples were taken every 24 h prior the regular
feedings. The gas production rate was measured by water displacement method described by Parajuli13. The biogas
concentration were measured by gas analyzer GA-m Binder Combimass® by taking 3 L of gas sampling volume
directly from the digesters. Slurry samples were taken at 600 mL from the effluent of the fermentation and stored in
an air-tight container with temperature set to 4 °C prior the analysis.
Total solids (TS) and Volatile solids (VS) of substrates and slurry samples were measured according to the
standard methods provided by US Environmental Protection Agency (EPA)14. Samples of CD and CH, each in