Screw Pumps for Sludge – How They Work and What You Should Look For

Screw pumps are designed to move liquids, solids, or liquid-solid combinations from one area to another. It’s a simplistic, yet effective, way to push liquids, sludge, grains, and other items along a chute or tube without clogging. Lakeside screw pumps operate at a constant speed, which lowers the chances of the machine needing maintenance or wearing out, making them a cost-effective piece of equipment. While these pumps can handle most everyone, one area where they’re very effective is pumping sludge.

Original Screw Pumps Go Back to Ancient Egypt

How do screw pumps work? One of the original uses of a screw pump was for agriculture and drainage. The screw pump set in water in a low-lying area and the top collection area sat in a higher area. As that screw twisted, water collected in the spiral tube and moved upwards to the collection area at the top. That brought water from a lower area like a river up a bank or slope to the garden beds or fields above.

The Egyptian Screw is believed to be the first screw pump and it was used to move water from the Nile River up the banks and to the villages and fields. While people know screw pumps as Archimedes screw pumps, evidence that Archimedes had any part of the invention is sparse. The pump was around for two centuries before Archimedes’ name is mentioned.

One of the first major uses of the Archimedes pump was in the 1600s when the Dutch used them to move water through dikes and canals. Windmills powered the screw pump bringing water from one section to another.

To understand how they work, imagine a long screw that’s sitting inside a straw. The bottom of that screw sits in a water-filled sink or basin. There’s a second bowl on the counter. The screw is turned at a steady speed. The threads of the screw are designed so that they hold liquid. As the screw turns, water collects in the threads of the screw and the upward movement of the screw pushes the water up the straw. The straw’s walls trap that water from escaping out of the bottom. Eventually, water propels to the top of the straw where it spills into the upper chamber.

What Factors You Should Weigh When Choosing a Screw Pump

A screw pump can move more than water. They can move oil and other viscous liquids like sludge. Sludge is a combination of fluids and solids that forms a thicker material like mud. Most sludge brought to water treatment plants comes from residential and business septic tanks where it’s pumped out and transported through trucks, but it can come from a variety of other sources. In an agricultural setting, screw pumps can move grains from a truck to a storage container. Sludge can also come from food and beverage plants like breweries, wineries, and dairy processors.

This is important when it comes to purchasing a screw pump. You need equipment that matches your intended use. Consider these factors when you’re buying a screw pump for sludge.

Open vs. Closed Screw Pumps

The screw pumps at Lakeside Equipment can be open or closed. This is important to understand as it can make a difference when you finalize your choice.

Open screw pumps sit in a trough that’s made of steel or concrete. The trough is open at the top, which exposes the spiral screw to the environment. The bearings are protected in a sealed sleeve or have a lubricating system that helps prevent wear whether they’re submerged or not. The trough needs to be at an angle of 22 to 40 degrees for the screw pump to work effectively. Given that incline, you do need a substantial amount of space when setting up this type of screw pump.

What are the advantages of an open screw pump? They can handle variable capacities without needing additional controls to manage the variation. They are efficient and don’t clog. There’s no need for pre-screening the sludge you get. Maintenance is low, and you don’t need a wet well to operate them.

What about enclosed screw pumps? There are two types: Type C or Type S. Both of these screw pumps are housed within a tube. A Type C is in a tube that can rotate. Type S’s tube is stationary. Type C is best if you need higher lifts than an open screw pump. It also requires less space as it can be installed to have a maximum incline of 45 degrees. Type S can pivot to keep up with changes in the pumping rate. It requires more space with an incline range of 22 to 40 degrees.

Benefits to enclosed screw pumps include higher efficiency with Type C. If the pump needs replacing, you can simply have the new pump dropped into place, which makes replacement much more affordable. With an open system, concrete and grout are needed. Enclosed screw pumps require no costly grouting or concrete work.

Flow Rate

How quickly do you need sludge moved? How thick is that sludge? Flow rates vary, and you need to make sure that the screw pump you choose can move the sludge as quickly as you need it moved. At the same time, look at the PSI and horsepower to make sure the system is going to work efficiently for you. We can help you with open screw pumps that move as little as 90 gallons a minute to as much as 55,000 gallons a minute. If you need an enclosed screw pump, the Type S is capable of 90 to 10,000 gallons per minute, and Type C handle 540 to 35,000 gallons per minute.


How much room do you have? If you’re in a tight space, not every screw pump will work. When space is limited, the inclination of that screw pump needs to work with the available square footage. Imagine you have a screw pump that If you have plenty of room for the screw pump’s installation, you will have more options.

The open screw pumps manufactured by Lakeside Equipment range in size from 12 inches in diameter all the way to 144 inches. Enclosed screw pumps are available in 12 to 60 inches (Type S) and 24 to 120 inches (Type C). When you talk to our engineers, we’ll help you understand the pros and cons of open vs. closed screw pumps and which best suits your needs.


You’re spending money on a new or replacement screw pump. You want a system that’s designed to last. You want to get your money’s worth and that means a system that’s not going to require a lot of maintenance and upkeep. The screw pumps at Lakeside are designed to reduce friction that damages the screw pump’s parts. Very little maintenance is required to keep the screw pumps working like new.

Lakeside Equipment’s customer service team and engineers are ready to help you design and purchase the right screw pumps for sludge. Our screw pumps are made in the USA and give you the flexibility of open or closed designs. If you’re looking to replace or upgrade your equipment or are installing a brand new system, give us a call. We have decades of expertise that ensures you get the best system for your money.