assumed that the effluent VS was a part of the influent VS
with a residence time equal to the HRT, while for calculating
the SRTmin, it was assumed that the effluent VS had the same
SRTas the excess sludge. Due to the presence of channels and
dead zones in the sludge bed of the anaerobic reactor, the
actual SRT in the UASB is between SRTmax and SRTmin.