Grit Removal Application

Borrisoleigh Waste Water Treatment Works, Borrisoleigh, County Tipperary

Customer: South Tipperary County Council

System type:  1-off SKE GRT 200

System description: Grit Trap

Removal standard: 95% of grit 0.2mm and larger

System operation: Rotating paddle and air blower to elevate grit

Installed:  2008

Flow rate: Maximum supported 120 l/s



This waste water works is situated outside the Tipperary town of Borrisoleigh. The screened effluent enters the upper chamber via a tangential inlet. A rotating paddle creates a vortex effect, and all grit, sand and small stones fall to the sump in the base of the unit. Air is blown through a pipe to the base of the airlift system. As the air rises through the central discharge pipe, it carries grit laden liquid to a grit classifier for dewatering and discharge to a skip.

The system uses an air blower and a particular design of electro valves to ‘liquefy’ the grit and raise it through the hollow concentric shaft in the centre of the system. This is a simple and effective system, and it can be mounted, as in this case, in a cast concrete tank in the ground, or alternatively it can be used above ground in a fabricated metal tank.