Grinding up pipe-clogging solids

Franklin Miller, Inc.

The Trenton Sewer Utility handles wastewater and sewage generated from the city of Trenton, N.J. The utility typically processes 12 mgd, which can quickly rise to 27 mgd during storm events. For the past ten years, the facility has relied on the powerful grinding capabilities of several strategically placed Super Shredder Disintegrators to ensure that operations run smoothly.

“We have a combined system, which is essentially more complicated," said Leigh Jones, plant superintendent. “We’re dealing with sewage from homes, businesses, and industries as well as enormous amounts of rocks, trash, grass, wood and other debris that wash in from the streets.”

A network of lift stations and gravity collection systems carries effluent into the central pumping station at the plant site where the material is distributed through the treatment processes. Concentrated sewage that has settled out as sludge is collected and sent downstream from the pumps, pulled through a Super Shredder and ground up. This step prevents the pumps from clogging. The sludge is sent to the primary digester and then transferred to a heat exchanger where hot water tubes treat it. Before entering the heat exchanger, the sludge passes through another Super Shredder , effectively preventing residual debris from clogging the tubes.

The utility has four of the disintegrators, but only two are in service at any given time. “Most plants have tandem shredding systems so if one unit goes out of service, you can switch to the other one,” Jones said. “Our spacing doesn’t allow for this configuration. The shredders were an add-on to the original design and there is no room to build in redundancy. The space saving Super Shredder meets our needs because we can use one shredder at a time. The unit in service can be easily pulled out for repairs and a spare slipped in. Fortunately, we don’t need to use the rebuild services very often, but when we do, we’ve been very pleased.”

“The units have saved us a lot of maintenance and downtime,” Jones said. “They’re well worth the investment.”

The in-line disintegrator 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 for 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 unit 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 Super Shredder has far fewer moving parts and requires much less maintenance than units with banks of cutter disks. The disintegrator’s replaceable one-piece cutters make maintenance convenient and down time minimal. Included with the disintegrator is a S-250 auto-reversing control system that senses jam conditions and automatically reverses.