Issue: 6/06

What is a pulper? Sometimes referred to as a grinder, shredder or even "a disposer on steroids,"

The Waste Xpress pulping unit from Insinkerator.

Disposers vs. Pulpers

While a garbage disposer can only process food articles with limited amounts of paper, most pulper manufacturers have developed systems with the capability to process disposable serving and packaging materials as well. This tends to yield significant volume reduction due to the high amount of void spaces in such items. This has allowed school districts such as the Broward County School System in Fort Lauderdale, FL, to experience significant savings for over 30 years.

The WastePro pulping unit from Hobart.
The advantages of the pulping system in comparison to the use of garbage disposals, commonly referred to simply as disposers, are relative to water consumption, loading of sanitary sewer systems and total waste processing. The operation of a disposer relies on finely macerating the solids and adding sufficient amounts of water to flush those solids through the sanitary sewer to the wastewater plant. This results both in high freshwater consumption and heavy solids loading at the wastewater treatment facility. In contrast, the pulping system typically produces a slurry containing larger, more coarsely cut solids that are more effectively captured in the extractor for disposal in the solid waste stream. Only a fraction of the water is let down the drain in the form of overflow, a process necessary for the system to dispose of excess liquids in the waste stream. While this discharge is heavily solids laden, these solids still represent a mere fraction of the solids processed. The majority of the liquid is recirculated back to the pulper. Finally, whereas the disposer is capable of handling only organic materials-typically the food waste and a small portion of paper-many pulper manufacturers have developed cutting systems capable of cutting other materials for total waste processing. These systems can process not only food waste but also all of the paper and the majority of the plastics and foams commonly used as packaging or as serving articles.

A close-coupled unit from Champion Industries.

Benefits of Pulpers

Users of pulping systems experience the benefits of volume reduction and material handling, as well as freedom from the tedious task of sorting their waste for disposal. The volume reductions possible using a pulping system can be as high as 10 to 1, and the entire waste stream can be fed into the system except for metals, glass and cloth. Reductions in trash hauling and labor costs are quickly realized, with a return on investment that is often less than two years.

The Somat SPC-75 pulper is installed here as a close-coupled unit where pulping and extraction units are combined into one machine.

Pulping Logistics

Pulping systems can be described as being either close coupled or remote. The close-coupled system is characterized by both the pulping and extracting units being integrally linked, essentially working as one machine. The material handling benefit from a pulping system is realized with the remote location of the extraction unit some distance from the pulping unit. These systems are commonly referred to as engineered systems due to the fact that they require more forethought than a standard close-coupled system. The machines are connected by piping and wiring lengths, and the pumping and piping systems must be properly suited for the distances involved. These systems can be simply one on one, involving a single pulper and a single extractor, or there can be a multitude of pulping units supplying a single extractor system. The benefit is a "hands-free"