Any clean-water plant operator knows the challenges posed by wipes and other nondispersible items coming in through the collections system.

These solids can clog lift station centrifugal pumps, as well as check valves and screens, driving up costs for maintenance, repair and operations. While screening systems remove much of this debris, they cannot keep all harmful materials from reaching treatment plant pumps. Therefore, many facilities resort to grinders, shredders and choppers.

Now pump manufacturer Gorman-Rupp is offering the Eradicator solids management system for its Super T Series self-priming centrifugal pumps. The technology, offered as original equipment and as an upgrade to pumps already in the field, helps to reduce clogging by efficiently passing stringy materials through the pump.

Vince Baldasare, sales manager for engineered systems, and Jeff Hannan, product manager for centrifugal pumps, talked about the technologies in an interview with Treatment Plant Operator.

How do the Super T Series pumps fit into the wastewater collections system?

Baldasare: The pumps are available in discharge sizes from 3 to 10 inches and deliver flows up to 3,400 gpm. Pumps 4 inches and larger are engineered to allow up to 3-inch-diameter spherical solids to pass through. Pumpout vanes on the two-vane impeller shroud reduce foreign material buildup behind the impeller and reduce pressure on the seal and bearings.

What market need drove the development of the Eradicator system?

Baldasare: In talking with industry experts, we learned that running wipes through a chopper pump is not necessarily a good thing, because they can re-form into balls later on in the system. Engineers told us they wanted those wipes to pass through as whole as possible so that they could get caught in the screens at the headworks of the treatment plant. For us, it was easier to come up with a technology to adapt our Super T Series pumps than to develop a whole new pump or a whole new rotating assembly. The Eradicator system doesn’t chop or shred; it lets the wipes go through and continue down the force main.

What sorts of materials have tended to cause trouble for centrifugal pumps?

Hannan: As the wipes break down, they get into strands and fibers. That is what starts to congregate at the eye of the impeller and block up the pump. It balls up, and once that starts, it accumulates almost exponentially. The Eradicator is designed to dislodge the material from congregating at the eye and move it through the pump.

What does the system consist of?

Hannan: It has three components. There is a back cover on the suction side. There’s a wear plate that has a tooth and also has notches and grooves cut into it, as opposed to a smooth surface in the typical design. Then we have a lightweight inspection cover that the user can easily pull off if something were to get lodged inside or if they want to check clearances. It gives access right to the eye of the impeller without having to remove the cover plate.

How does this design prevent pump clogging?

Hannan: The flow enters the pump through the suction side and drops down into the eye of the impeller, which centrifugally throws the water to the outside of the casing; it discharges through the top of the pump. As stringy material catches on the leading edges of the impeller vanes, the notches and grooves in the wear plate pull at it to dislodge it. Meanwhile the tooth has a fairly close clearance to the leading edge of vanes. When the impeller vanes pass by the tooth, anything that has collected on the leading edges gets pushed off and moved on through the system. In every rotation there are two wipes, because there are two impeller vanes.

Has demand for this technology increased recently?

Baldasare: Yes. With what we call the new sewage, everybody is flushing wipes. Now because of COVID-19, that has increased. With all the concern about cleanliness, people are using wipes more than ever, and sewer systems are even more laden with them than before. With our upgrade kit, we can easily adapt the Eradicator to 10- and 15-year-old Super T Series pumps already installed in lift stations. Someone who starts to have clogging issues who did not have them before can purchase an upgrade kit.

What is involved in retrofitting a pump?

Hannan: They basically just remove the back-cover assembly and bolt in the new one with the inspection cover and the redesigned wear plate. They can be up and running in a few minutes.

In what kinds of facilities has this product been deployed?

Hannan: About 3,600 of these pumps and upgrade kits have been installed in this country and around the world. Besides municipal lift stations and wastewater treatment plants, they are in use in poultry, pork and beef processing plants; wineries that have to deal with skins, seeds and stems from the grapes; and other industrial applications.