The grit separator consists of a shafted screw, fitted inside a semi-circular trough, which is angled at 25 degrees and has a settling chamber fixed to it. The trough or body is constructed of stainless steel and fitted with protective 3cr12 liner bars as well as the required fixtures for a motor, gearbox and support legs. The screw is driven using a motor-gearbox set, located at the top end of the trough. The separator has two grit inlet pipes and one water return pipe. The outlet chute is located at the top end of the separator, where it discharges dry grit into the waste container system. The separator is fed with a high grit content from the grit pump or airlift system. The grit settles out and after a pre-set time the grit separator screw starts, facilitating the removal of the settled grit from the hopper and discharging it into a waste container system. The return water will flow from the grit separator, directly into the start of the grit chamber, during the pumping cycle. The screw center shaft and flights are manufactured in 3CR12 and the separator body is constructed from 304 stainless steel. The bottom support bearing for the screw is positioned outside the classifier for easy maintenance.
One of the most common degritting systems is the vortex tank or chamber system, a circular continuous flow-through vortex grit settling chamber. This chamber is sized according to peak wet weather conditions. The chamber consists of an upper separation section where, because of reduced flow velocity in the tank, the grit will settle into a lower chamber. The settled grit in the lower chamber is then removed by an airlift pump, self-priming pump or submersible grit pump. The grit is further pumped into a grit classifier where washing and water separation is carried out.
The airlift pump, mounted above the grit chamber uses a dedicated blower air, compressed air, and wash water injection to move the grit slurry through the pipeline and into a grit classifier for further processing.
The Self-priming grit pumps, mounted above grit chamber, has a hardened recessed impeller that operates periodically extracting grit from the lower chamber. The pumped grit slurry is fed through the pipeline and into a grit classier for further processing.
Submersible grit pumps, mounted in the lower grit chamber, have a submersible tungsten coated body and impeller which operates periodically, extracting grit from the lower chamber. The pumped grit slurry is fed through a flexible pipeline to the top of the chamber for easy removal of the pump via lift davit.