What is Grit?
/Grit/ small loose particles of stone or sand, definition two, courage and resolve. For our talk we will stick with the first definition. One of the largest issues facing wastewater treatment facilities is how to move grit and choose the right grit pump.
Grit in the wastewater industry is often a mixture of rocks, gravel, glass and sand that is classified as 0.21 mm (0.008 in) (65 mesh) or greater, with specific gravity of greater than 2.65. In a pumping situation grit can cause a significant negative impact to centrifugal pumps.
Grit passes with ease. The arm of an adult can fit through a fully assembled EDDY Pump
Traditional Wastewater Pump Problems
Centrifugal pumps with a recessed impeller or any other configuration often have much difficulty pumping grit. They have been the standard choices in the past. That is until now, you discovered EDDY Pump.
The two main issues with old style pumps are clogging and the abrasiveness of the grit. Pumping large grit found in wastewater treatment facilities can often cause clogging for centrifugal pumps.
Why? Normally they have a close tolerance between the impeller and the volute. It is very costly to have a clog and creates a lot of downtime.
Next, the abrasives widdle the rotor down. In order to pump grit that is abrasive, a centrifugal pump will incur heavy wear and tear on the impeller. Based on the low and critical tolerance in a centrifugal pump, any wear will cause the pumps dynamics to be thrown off, reducing optimal efficiency. This in turn leads to an extreme loss in suction. The centrifugal pump then must be taken out of operation, rebalanced or replaced, which is very costly to the wastewater treatment plant (tax payers).
Wastewater plants often equip their grit pumps with comminutors and grinders in order to break up the material so that the centrifugal pumps can handle it. Once again, adding another layer to the process adds cost and intensifies the degree of maintenance involved.
A Better Grit Pump for Wastewater
EDDY Pump has a tested and multi decade proven solution.
Based on the EDDY Pump design which has a large and non-critical tolerance between the rotor and volute, it makes for the ideal grit pump. The EDDY Pump grit pump can pass an object without any issue that is 1-inch smaller than the intake of the pump.
Example, a 4-inch EDDY Grit Pump can handle a 3-inch solid without clogging or having any negative effect on the pump. Many pumps start clogging at half the diameter of solids. Another advantage of this extreme tolerance is that it is non-critical, plus reduced wear and tear because of less grit to rotor contact.
Finally, there is no need for comminutors, macerator or grinders with the EDDY Pump because it will pass all material without any issues.
Conclusion: Cost Reducing Grit Pump
The EDDY Pump has been utilized by the US Navy for over 20 years on almost all classes of Navy ships for grit, waste transfer and sewage pumping. The reason is that this pump design saves the Navy tens of millions of dollars every year in corrective action, overhaul, and downtime.
To see a Total Cost Analysis done by Lockheed Martin on the cost savings of 25 EDDY Pumps versus the leading centrifugal pump over 4 years, please click HERE to View the Analysis. Also see our resources section for white papers and more education.
Grit Pumps and Options for Wastewater Management