The Grit King^® is an advanced hydrodynamic separator that augments gravitational forces to separate grit from water. The Grit King^® is an economical choice for new or existing municipal or industrial wastewater applications.

The Grit King^® system is comprised of the Grit King^® unit and a grit washing / classification unit. Valving, grit classifiers, grit pumps, dewatering decanters, and control systems are available to provide a comprehensive grit removal package.

Applications

• New wastewater treatment plants
• Treatment plant retrofits
• Grit removal for potable water
• Grit removal for industrial effluents

Advantages

• No moving parts
• No external power source
• Recovers clean grit
• Easily linked with new or existing plants
• Economical to own and operate
• Compact design
• Minimal headloss

Flow is introduced into the Grit King^® via a tangentially positioned inlet causing a rotational flow path around the dip plate. The flow spirals down the wall of the chamber as solids settle out by gravitational and rotational forces. (red arrow)

The grit collects in the grit pot as the center cone directs flow away from the base, up and around the center shaft into the inside of the dip plate. (blue arrow) The upward flow rotates at a slower velocity than the outer downward flow. The resulting "shear" zone scrubs out the finer particles.

The concentrated grit underflow is pumped or gravity fed to a grit classifier for dewatering from the bottom of the Grit King^®

Cutaway View of the Grit King^® Process

Q. How can you minimise the headloss through a Grit King^® separator?

We recommend that the inlet velocity is between 3.3 and 4.9 fps at peak design flow and it may be necessary to adjust the inlet pipe diameter to maintain this. The system headloss will vary accordingly and it will be in proportion to the square of the inlet velocity.

Q. How do you decide whether to use a gravity system or a pumped system?

In most cases it is obvious which system is to be used. However it will be necessary to carry out detailed hydraulic calculations to assess if a gravity system is appropriate. The headloss at the inlet to a Grit King^® is 6’ above the centerline of the inlet pipe at the design flow of 318 gpm and there is a free discharge at the inlet to a grit classifier.

Q. Can the Grit King^® be used for other applications other than at wastewater treatment plant headworks?

Yes. We would request that the client provide a grading curve and a specific gravity for the material to be separated and this would provide the information needed to size the unit. If the material is colloidal or very fine then vortex separation may not be appropriate.

Q. What is the smallest below ground internals only installation that a submersible pump will fit into?

We ensure that the minimum diameter of the grit pot is 35.4” so that a wet well submersible pump will fit. The diameter of the Grit King^® Separator with this grit pot size is 7 ft.

Q. What dictates the height and position of the anti siphon valve on the pump feed to the classifier?

There are two reasons for raising the feed pipe above top water level in the separator. Firstly, to control the flow and secondly, to prevent siphoning. A detailed hydraulic calculation is required to calculate the hydraulics and size the pump.

Q. What materials are used for the construction?

304 Stainless Steel or 316 are used although other materials could be considered.

Q. What are the effects of flows higher or lower than peak design flow on the performance of the separator?

The unit will accept higher or lower hydraulic flows than the peak design flow. However, if the flow is higher than the design flow - the headloss will increase and the performance reduce. If flows are very low then organics will settle out with the grit.

Q. Do you require access to the top of the Grit King^® Separator?

There are no moving parts at the top of the Separator and therefore access is not required for routine maintenance.

Q. Is the system able to operate on unscreened sewage?

We recommend that the Grit King is operated after screens as in our experience the influent at a sewage works can contain very large objects. Also, if we are operating with a pumped system, rag balling can create a problem. In special circumstances and depending on the specific circumstances we would consider installing upstream of screens but this would not be our preferred option.

Q. Does the system ever block?

It is important that the recommended control philosophy is followed and under these circumstances blockage problems are unlikely. If the control system is switched off for a prolonged period with flow continuing to run through the separator then grit will continue to be collected in the grit pot and could build up to a level where it would be difficult to mobilize again. It is therefore important to be able to isolate the separator when the process control is switched off.

Q. Water or air backwash within Grit King^® Separator? Which is preferable?

Either. The decision will depend on the availability and cost of water on site. Some sites have remote inlet works without a nearby water supply and in this case, an airset may be preferable to providing a new water supply.