"You get the rope, the diapers, wipes. They have a tendency to plug things up, and that becomes a real problem," said Aaron Eichhorst, a wastewater treatment operator at NEW Water. "A wastewater treatment plant is designed to treat biological waste, not garbage." (Green Bay Press Gazette, September 29, 2014)
While those in the wastewater treatment field are aware of this growing problem, many people are not. In June, we published It's a Toilet, NOT a Trash Can explaining the impact of wet wipes and other non-flushable materials (ragging) on treatment plant systems and what operators can do to help prevent costly problems. Today, we'll expand on the topic and discuss four specific technologies we've been recommending to our customers for tackling ragging.
A number of our municipal customers have had success with these pumps. Before installing the ABS Effex submersibles they would have constant clogging issues. Once they tried the ABS, they never went back, in fact, many of them replaced other pumps in their plant with the ABS Effex.
These pumps are engineered to handle tough wastewater conditions with their IE3 Premium- Efficiency motor and blockage resistant impellers. The Contrablock Plus impeller (available in single-vane and multi-vane models) technology allows for the passage of 3" solids through the impeller. The vast majority of fibrous material is passed through the pump using the impeller vane rather than relying on the cutting action provided by the impeller's bottom-plate interface.
The Sulzer-ABS XFP submersible sewage pump is designed for both wet and dry pit applications, and is recommended for pumping sewage containing solids and fibrous material. They are ideal for commercial, industrial, and municipal applications.
This pump was specifically designed to address ragging issues. This pump's unique stationary and rotating blade design reduces the size of solids, so they will pass through the pump without clogging it.
We love that you don't have to purchase an entirely new pump to cut back on the clogs, the cutter blades can be retrofitted onto existing Cornell pumps without changing external dimensions.
This list wouldn't be complete without mentioning Gorman Rupp Self Primers. Gorman Rupp pumps have been our go-to solution for many years due to their long history of solids handling experience and ease of maintenance and installation.
These pumps have a two-vane, semi open impeller that allows solids to pass through without incident.
These pumps, when properly cared for, can provide many, many years of trouble-free service. Being above ground makes them easy to maintain as well, versus the submersible pumps.
As a last line of defense at the wastewater treatment plant, screens can be implemented to prevent clogging in pumps at the plant.
Coarse screens remove rags, sticks, large solids, and other debris ranging from .25 to 6 inches with bars or rods. Fine screens (static wedgewire, step, and rotary drum screens) use wire cloth, wedgewire elements, or perforated plates to remove smaller particles that could cause maintenance problems down the line. The openings range from .06 to .25 inches.
Check out Screening at a Glance: An Introduction to Wastewater Screens for more information about wastewater screens.
Ragging has been a serious problem for a long time, and though more awareness is being raised for the cause, the problems continue to trouble wastewater operators. There's not a lot you can control when it comes to rags, but you can control the equipment you choose to combat it.
Please note: There is not a "one size fits all" solution for ragging and clogged pumps. Each situation must be evaluated to determine the most appropriate plan of action.
If you have a pump that's constantly causing you headaches because of ragging or clogs, simply ask us about it or consider our free Bad Actor Pump Assessment below! Our team of Water & Wastewater Engineers are standing by to help businesses and municipalities in Wisconsin and upper Michigan.