Even though, CODcol removal varied as also found in other studies (e.g. Sayed and Fergala, 1995) in which the limited entrapment was reported to be due to sludge bed porosity and upflow causing lift-up of colloidal material, CODcol contributed only to minor amounts of the CODt. The results suggested that with synthetic BW single-phased UASB-septic tank may be sufficient for good COD and solid removals also at 10 1C, while with DPWW a two-phased system is needed to achieve similar removals at lower temperatures.