The maximum conversion to methane (ABmax) is an
important parameter for evaluating the anaerobic treatment
of any wastewater (Elmitwalli et al., 2001). Determination of
the ABmax is carried out in batch experiments either by
addition of inoculum or without. Inoculum addition represents
inaccurate method due to production of dissolved
organic matter and biogas from decay of the inoculum, while
experiment without inoculum addition suffers from a long
operational period. Elmitwalli et al. (2004) determined the
ABmax of the pre-treated (in septic tank) grey water with
inoculum addition at 30 1C. They found a high ABmax for the
pre-treated grey water (86%).