A fluid’s thickness and flowability dictate the type of pump you need.
For sludge removal, including sewage sludge removal, a solids handling pump, aka a trash pump, can often — but not always — do the job. When it can’t, a sludge pump probably can.
Some people use the terms “trash pump” and sludge pump” interchangeably, but these pumps are not the same. Knowing when to use a sludge pump is critical to successful sludge pumping.
What is a sludge pump?
A sludge pump is a heavy-duty hydraulic or electric pump designed to move thick fluids with a high solids content, such as sewage sludge. Sludge pumps have the horsepower and the impeller design and size to create the high degree of suction needed to move solids through a system.
A sludge pump also has a stirring capability for removing settled solids from the bottom of a tank, pit or other container.
Sludge pumps, which are typically submersible, are used for many applications across a host of industries, including these:
- Municipal wastewater plants: Desludging clarifiers and sludge thickening basins and removing grit from the bottom of tanks
- Refineries and chemical plants: Cleaning out treatment process tanks and long-term storage tanks
- Agricultural operations: Desludging ponds and pits used in wastewater systems
What is a solids handling pump?
A standard solids handling pump, aka trash pump, is a diesel or electric pump that can move liquids that contain solids up to 3 inches in diameter, depending on the pump, with a solids concentration of 3% to 5%. These pumps are available in a wide range of sizes and pumping powers.
Solids handling pumps come in submersible and above-ground models. Your pump vendor can provide guidance on which type of pumps is best for your location and application. With an above-ground pump, you’ll likely need vacuum assist to maintain the necessary flow.
Solids handling pump applications include:
- Construction companies: Dewatering construction sites and excavations that contain dirt- or sediment-laden water
- Municipalities: Moving fluids in sewer and stormwater bypass systems
- Industrial plants: Draining containment areas around storage tanks
How to choose the right type of pump for sludge removal
A solids handling pump will be sufficient for sludge removal as long as the fluid can move easily through the pipe. If the sludge is thicker, you’ll need a true sludge pump. Even a larger solids handling pump may rag up when used to move sewage.
A rough rule of thumb: Use a sludge pump when the fluid contains solids at a concentration of 6% to 7%. You’ll also need a sludge pump to remove settled solids and semisolids.
The importance of professional input and installation
It’s not always easy to know which pump you need. Choosing a solids handling pump when the material requires a sludge pump can lead to clogs and failures. Moving sludge that is too thick even for a sludge pump will likely tear the pump.
An experienced pump vendor can help you assess the fluid you need to move and guide you in choosing a pump that will meet your requirements.
Professional installation is also important. United Rentals will set up and install sludge pumps for optimum performance. Adjusting them after setup to increase the flow and get the job done faster very commonly results in pump failure, which leads to project delays.