SEDIWASH: Grit Washer

DRYCAKE DGW grit washers offer a solution to removing, washing and dewatering grit and sand, in addition to protecting downstream mechanical equipment and improve the performance and reliability of drainage systems.

The Grit Washer consists of a shaft-less spiral screw conveyor and conical hopper. Effluent flows into the hopper where the grit and sand settles out. Settled grit is conveyed, washed and dewatered within the screw conveyor, then disposed of into a container

Operating Principle

Effluent contaminated with grit and organic matter discharges into the top of the hopper close to the periphery where a coerced, slow rotational movement is produced and aided by the central stirrer. This rotational movement together with sufficient retention for variations of particle settling velocities induce the grit and sand to spiral and settle by gravity to attain > 95 % removal of 0.20 – 0.25 mm (200 μm – 250 μm) size grit particles.

Maintained flow velocities prevent any suspended organic matter from settling with the mineral. Furthermore, wash water enters from the screw classifier into the bottom of the hopper and, aided by the central stirrer, the grit and sand particles abrade against each other scouring any attached organic matter from their surface. This scouring process is further enhanced by air agitation. Eventually, the grit is conveyed by the screw classifier, washed, dewatered and discharged into a container. Removal of organic matter > 97 % is attainable.

Suspended organic matter discharges from the classifier hopper at intermittent frequencies and can either be returned to the flow and onward to secondary treatment or back to the works inlet.

The option of continuous bagging systems are available to receive the grit and abate odour, the grit can then be sealed without any personal contact.

SEDIWASH Specifications
Flow Capacities Up to 22 l/s (80 m³/ h)
Fabrication: AISI: 304 or 316
Grit Removal Efficiency ≥ 95% grain size ≥ 200μm (0.2 mm)
Volatile organic reduction ≥ 97%
Organic content ≥ 3%
Dewatering efficiency 90% dry residue
Typical Applications
  • Municipal waste water treatment works
  • Small sewage treatment works
  • Industrial effluent discharges
  • Receiving Grit from Sewers or Gullies
  • Grit Recovery from Processing Plant
DGW: Grit Washer

Typical Arrangements:

Wastewater Treatment Works
Grit Recovery from Processing Plant
Grit Chamber

Product Information