Flushable: A Subjective Term

Grinding technology reduces tough solids in California

Each day, the Northline Lift Station in Laguna Woods, Calif., transports sewage generated by 33,000 domestic users to The El Toro Water District Water Recycling Plant. The wastewater treatment facility serves five cities and is one of the oldest water recycling plants in Orange County. The district has successfully kept pace with the water demands of a growing population through an innovative combination of process technologies and enhancements that promote conservation and recycling.

For years, three pumps installed at the Northline station easily handled an average flow of 2.5 million gal per day, and could even manage the heavy flow from an occasional El Nino deluge. The crew had to deal with the usual assortment of rags and other debris, but maintenance generally consisted of deragging the pumps every three months.

“Then in 2007, we saw a real change,” recalled Bruce Walczyk, pump station foreman. “Flushable wipes came on the market. Although they were advertised as being safe to flush, these products did not degrade before they got to the sewer pumps.”

The wipes tended to bind and clump together, creating huge balls that became tangled in the pumping equipment. The pumps needed to be cleared manually. Screw tools were used to reach in, loosen up and pull out the packed debris, a hazardous and time-consuming task.

“The situation worsened as the wipes became more and more popular,” Walczyk said. “Eventually, it was taking two men four hours each, three times a week, to derag the clogged pumps. They often would be out at midnight on Sunday fixing a jam.”

It became apparent that a unit to pre-shred the debris before it reached the pumps was desperately needed. Dale Gruel of Dudek Consulting Engineers, Encinitas, Calif., recommended grinding technology to alleviate the problem. After evaluating several units, the pump station crew chose a Franklin Miller Super Shredder SS1200 In-line Disintegrator . Space was an important consideration and the company was the only one that made a unit with a short lay length that would fit into the site.

The Super Shredder SS1200 was installed next to the inlet flow at the suction side of the pump. The debris was sucked in, shredded and then easily passed through to the treatment plant. This placement avoided the potential for clogs and blockages of the pumps further down the line.

“The unit has so many great features,” Walczyk said. “Recently, a couple of pieces of metal got into it. The Super Shredder reversed and unclogged itself and we were able to pull the metal right out.”

“Since its installation, the Super Shredder has run flawlessly, saving us countless labor hours. We’re now inspecting the pumps for only a few hours once a month,” Walczyk added.

The Super Shredder easily reduces tough solids directly in sludge or raw sewage lines. The unit combines unsurpassed grinding capabilities with streamlined, easy-to-maintain features. Its innovative design provides a high level of open area to fluid flow, making the Super Shredder ideal for applications requiring a heavy-duty size reduction processor that can handle high flows with minimal headloss.

The Super Shredder features a patented spherical shredding mechanism that cuts and shears tough sewage solids into fine bits. The hard-faced stainless steel cutters offer unsurpassed wear resistance. Because of the spherical rotor design, the unit has far fewer moving parts and requires much less maintenance than units with banks of cutter disks. With two easily replaceable one-piece cutters, maintenance is convenient and down time is minimal. Included with the Super Shredder is an S-250 auto-reversing control system that senses jam conditions and automatically reverses.

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