The grit tank removes heavy inorganic materials such as sand, grit, egg shells, road pavement and glass from sewage flows.

The comminuted sewage flows through the inlet channel into the 12'x12'x12' grit tank where it is 'rolled over' several times during a detention period of approximately 5 minutes. The rolling action in the tank is produced by diffused air introduced at the bottom of the tank. A blower located in the grit storage building supplies the air. While sewage is in the tank, organic solids which have a low specific gravity will remain in suspension while heavier inorganic solids (grit) settle into the collection hopper. The gris is pumped out of the tank to the grit washer with an airlieft. The grit is then dewatered and loaded into a hopper for disposal. Degritted sewage overflows the tank's effluent weir and continues on to the primary clarifiers' division box.