Tips for Choosing a Wastewater Pump for Your Lift Station

June 30, 2020

Wastewater pumping is a crucial process performed at lift stations and wastewater treatment plants in Missouri and beyond. These pumps keep the entire station running; they must be capable of operating reliably at all hours of the day.

When lift stations need new wastewater pumps, there are a variety of factors they must take into consideration, including the flow and head, the installation orientation, any space constraints they have at their facility, the fluid type the pump will be dealing with and the solids they’re likely to encounter.

Here’s a quick overview of some of the types of wastewater pumps and impellers a lift station may select from:

  • Dry pit pumps: These pumps get installed next to sumps or wet wells, and allow the use of a centrifugal pump and motor. These pumps keep the pump out of the wastewater, which has the advantage of allowing technicians to diagnose pump problems during operation, as the pump is not covered in sewage. However, there is a greater possibility of flooding with a dry pit pump, and water getting into the dry pit could destroy the pump motors.
  • Submersible pumps: These pumps are used directly in the wastewater. They feature a sealed motor to protect the mechanical and electronic equipment, so there’s no need to create a separate dry well, which will save you money. Of course, access to the pumps is limited, because the pump itself is surrounded by sewage. The pump must be removed with a guide rail system before it can be inspected or serviced.
  • Self-priming pumps: This type of pump is located above ground, and used primarily for suction lift applications (such as lift stations). They work by extracting air from the suction side, then discharging it into the wet well. They are designed to pass solids, and will have a longer life than submersible pumps because they are located in a clean atmosphere and allow easier access for maintenance, similar to dry pit pumps.

The pumps listed above will also typically be fitted with one of these types of impellers:

  • Vortex impeller: This impeller is used in applications that have major issues with ragging, and is found in submersible or dry pit applications. They get installed in the top of the volute and away from the flow path. This impeller forms a whirlpool that carries solids and water through the pump and out the discharge area without any direct contact, cutting down the risk of clogging and wear and tear to the impeller.
  • Semi-open impeller: This type of non-clog impeller has a back shroud with only a couple vanes that is capable of passing solids of up to three inches using a three- or four-inch submersible pump. With fewer vanes, there are larger impeller openings to allow those solids to pass by. This is the standard impeller for all above-ground pumps.
  • Enclosed channel impeller: This type of impeller has a front and back shroud, which makes enclosed channels for the solids and wastewater to pass through. It is a highly efficient type of impeller.

For more information about the various types of pumps and impellers used in wastewater pumping in Missouri, reach out to the experts at Enviro-Line Co., Inc. today.

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