Abstract: A vortex grit trap comprising a generally vertically extending tank of circular cross-section including a separation zone having an inlet and an outlet for liquid flow to and from the tank, and in which liquid is circulated about a longitudinal axis of the tank, and, a grit collection zone positioned beneath the separation zone in use, the trap being characterized by a generally circular tank divider centered on the vertical longitudinal axis of the tank and extending transverse thereto, the divider defining a notional boundary between the separation and collection zones of the tank and being of smaller diameter than the adjacent region of the tank so as to define with the adjacent tank wall an annulus through which grit passes from the separation zone to the collection zone in use, and, means for generating a cloud of gas bubbles migrating in use upwardly through substantially the whole of said annulus whereby substantially all grit passing from the separation zone into the collection zone passes through the

Abstract: A washing apparatus for washing solid fractions such as screenings or grit derived from a sewage treatment plant and contaminated with fecal material, such as fecal solids, includes a tank (11/111) for receiving aqueous liquid and the contaminated solid fractions, and mechanisms (23, 26, 126) for generating turbulence of the aqueous liquid in the tank to break-down the fecal contaminants. The method of washing screenings includes adding aqueous liquid and screenings contaminated with fecal material to a tank, subjecting the liquid containing contaminated screenings to turbulence to break down the fecal material and adding further liquid alone or containing screenings to the tank such that screenings and aqueous liquid containing finely divided fecal material flow from the tank over a weir or the like for dewatering and compaction of the screenings.