2.3 Analytical methods
The samples taken were analyzed for total solids
(TS), volatile solids (VS), and chemical oxygen demand
(COD) using the Standard Method [4]. Ammonia nitrogen
(NH3-N) content was examined using the
spectrophotometer (HACH, DR/2500). The composition
of methane in the biogas produced was analyzed using a
gas chromatography equipped with a thermal conductivity
detector (TCD). The column used was a HP Molesieve
30m × 0.53mm × 0.05mm capillary column. The injector
oven and detector temperatures were set at 150o
C, 60o
C
and 200°C, respectively. Argon served as the carrier gas
while nitrogen was used as the makeup gas.