The results demonstrated that the CODss followed by CODcol
represented the major part of the grey water CODt. In the domestic wastewater and black water, the major part of
CODt is CODss followed by CODdis (Levine et al., 1985; Gaillard,
2002). The particulate (suspended+colloidal) COD represented
about 80% of grey water CODt, while it corresponded to
65–75% of domestic wastewater CODt (Wang, 1994). The
higher content of particulate in the grey water is due to the
increase of the CODcol percentage (30–35% of CODt), while it is
25–30% in the domestic wastewater CODt (Elmitwalli et al.,
2002b). The relatively high percentage of the CODcol in the
grey water might be due to the presence of surfactants and
lipids in the wastewater. The percentage of CODss was almost
similar in both grey water and domestic wastewater (40–50%
of CODt), while the percentage of CODdis was higher in
domestic wastewater (25–35%), as compared to grey water
(18–20%).