2.3 Chemical analyses
Effluent samples were taken from the reactor every 1-3 days under
different stages. The total solids (TS), volatile solids (VS) of the
substrates and effluent were measured with dry methods to a constant
weight at 105°C for 24 h in an electric heating air-blowing drier and at
600°C for 2 h in a muffle stove, respectively (Sluiter et al., 2005).
Total and soluble chemical oxygen demand (TCOD and SCOD), and ammonium
nitrogen were sampled every three days, and then measured with standard
methods (APHA 2005). Contents of C, H, O, N, S were measured through a
Macro Element Analyzer. The biogas (CH4 and
CO2) composition, volume, VFAs and pH were determined as
previously described (Mahdy et
al., 2019b). One-way analysis of variance (ANOVA, p<0.05) was applied to identify the statistical significance.