New Technology Helps Treatment Plants Deal Efficiently With Wipes and Other Tough Solids

Wipes Ready technology brings a new approach to wastewater grinders and helps treatment plants deal with a persistent and growing problem.
New Technology Helps Treatment Plants Deal Efficiently With Wipes and Other Tough Solids
The cutter reduces wipes and other inorganic solids to small particles.

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No one in clean-water operations needs to be told that wipes are a problem. Utilities try to educate residents to keep wipes out of their toilets. Wipes manufacturers are working to make their products more flushable.

In the meantime, though, wipes continue to get into collections and treatment systems, where they can clog pumps and cause expensive maintenance problems. That calls for mechanical solutions, most notably sewage grinders.

JWC Environmental, a longtime grinder manufacturer, has developed a technology to help utilities deal with wipes effectively. The company’s Wipes Ready technology, available for its Muffin Monster and Channel Monster grinders, received a 2017 Innovative Technology Award from the Water Environment Federation.

Available in new grinders and for retrofits in the field, the technology was recognized for its 17-tooth cutter with serrated edges, a design that cuts wipes and other material in two dimensions, producing a controlled particle that does not reweave into pump-clogging rag balls. The design also includes features to maximize the capture of wipes and feed the material into the grinder.

Rob Sabol, director of research and development, and Kevin Bates, director of marketing and product management, talked about the technology in an interview with Treatment Plant Operator.

TPO: What was the driving force behind the development of this technology?

Sabol: The aim was to reduce the inorganic solids in wastewater and protect pumps and downstream equipment. Many wipes by design are very resilient, and they are tough to grind. Customers told us they were having problems with these wipes getting into pumps and causing shutdowns. The material had evolved beyond the capability of existing technology; we had to do something different to break those wipes down.

TPO: How would you describe your approach to the problem?

Sabol: First, we looked at the nature of the cloth and did a lot of research and testing of the different kinds of wipes — how they were designed, how they were held together, and how to break them down. We quickly learned that not all wipes are created equal. One thing we found was that if you cut the wipes into strips, the resulting material would twine itself with hair, grease and other debris in the waste stream and form rag balls. We saw a need to break wipes down into a geometry that’s less susceptible to rag ball formation.

TPO: What kind of geometry is that?

Sabol: We wanted to create pieces small enough not to twine with other materials but also large enough not to pass through screens at the treatment plant headworks. Our goal was a confetti cut: particles about a 1/2- to 3/4-inch square.

TPO: How is that accomplished in the cutting mechanism?

Sabol: Two-shafted grinders are very good at cutting in one dimension, in strips. We had to find a way to cut in two dimensions. The breakthrough was the serrations on the cutters. If you look at a roll of Scotch tape, you drag the tape across a serrated blade. The serrations weaken the material so that it breaks when stretched or pulled. So, the Wipes Ready cutters have serrated teeth that perforate the wipes. And then the differential speeds of the two shafts create a tearing action. That breaks the material into roughly square pieces.

TPO: How does the technology enable the optimum capture of wipes for cutting?

Sabol: We took a two-pronged approach. While developing the Wipes Ready cutter, we looked at how we could enhance the side rail to not only allow water to pass through, but also promote material entry to the cutter. On the Muffin Monster, we have Delta-P side rails with a delta shape, creating a pressure gradient that directs the water flow toward the cutter, so we can get very high volumes of water to pass through and still get great capture efficiency. On the Channel Monster, we can increase the flow even more by replacing the Delta-P side rails with a rotating perforated drum filter. The 1/2-inch hole spacing we use is key to capturing solids and delivering them to the grinder for breakdown while also preventing the stapling of hair and other materials on the outside of the drum and preventing the buildup of grease.

TPO: Does this technology include any other design innovations?

Sabol: Yes. Optimum Cut Control gearing works with the Wipes Ready cutter. Through testing, we determined the gear ratios in the two counterrotating shafts that create the tearing action to achieve the optimum particle size reduction. We also optimized the clean-out of the cutting chamber to enable processing of material through the system as quickly as possible.

TPO: What are the relative shares of new Wipes Ready installations versus retrofits?

Bates: We’re seeing interest equally across customers who already have our equipment and those who need a new grinder in the collections system. As sewage has changed, existing customers have been able to upgrade their systems. Wipes have been growing at 5 to 6 percent a year since 2000, so people who never had problems before are starting to have problems.

TPO: Can you describe the experience of a specific customer who uses this technology?

Sabol: The Rancho Santa Margarita Water District in California had four pumps protected by two-shafted grinding equipment. They were de-ragging the pumps about every two weeks. In 2014, we changed their Channel Monster grinders to the Wipes Ready design with perforated drums and Wipes Ready cutters. They went from de-ragging every two weeks to zero.
Bates: They also realized about $80,000 a year in electricity savings because they no longer have rags in their pumps reducing efficiency. Early adopters like this agency really helped prove out the technology.

TPO: How would you assess the effect of this technology on the industry?

Sabol: It’s a terrible job to unclog a sewage pump. Nobody wants to do it, and the safety aspects of it for the workers are significant. JWC Environmental didn’t ignore the problem. We didn’t go out and try to solve it in a closet. We partnered with people. We talked to customers about their needs and developed a product that deals with the problem successfully. Making that kind of impact on the industry from the company’s and my own perspective is really satisfying.


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