For the UASB reactor, it was assumed that 75% of the
measured biogas was methane (based on the biogas composition
in previous studies in the treatment of domestic wastewater
in the UASB reactor, Halalsheh, 2002; Mahmoud, 2002;
Elmitwalli et al., 2002b). The amount of dissolved methane in
the effluent was calculated according to Henry’s Law.
Calculating hydrolysis or methanogenesis based on influent
and removed COD aims at evaluating, respectively, overall
performance of the reactor and capacity of the biomass in the
reactor in anaerobic digestion of the wastewater, as explained
by Elmitwalli et al. (2002a). For calculating the SRTmax, it was