Pulper Proposition

When planning his $400,000 redesign of BryanLGH Medical Center’s dishroom, Dean Young, director of nutrition and dining services for the Lincoln, Neb., facility made sure kitchen designers worked his existing pulper into the design. “It was only seven years old at the time and we keep it in top condition,” he says. “There was no way we were giving it up; it’ll last another 10 years, easily.” With the pulper, Young’s kitchen gets by with two additional 45-lb. garbage cans for glass, metal, and a rare few other items that can’t go into the pulper.

Pulpers, with 5-hp, 7.5-hp, and even 10-hp grind motors, shred all kinds of trash, including food waste, cartons, Styrofoam, plastic, light aluminum cans, and paper. The process adds water to the mix to create a slurry in the grind chamber. The wet, shredded waste travels to a liquid extractor consisting of a rotating auger that pushes the wet pulp up and out through a discharge chute.

The action presses most of the water out through a perforated screen encasing the auger. Most units operate using about 2 gpm to 3 gpm of fresh water because they recirculate the water that’s extracted back to the grind chamber. Since less water is sent down the drain, sewer costs also are lowered. The end result is a semi-dry pulp that drops into a trash bin.

Suppliers report pulpers will reduce the volume of your trash 70 percent to 85 percent. If your operation generates a lot of garbage, you’re lacking space to store garbage, you’re a high-disposables user, or your trash hauling costs or garbage fines are just too high, a pulper could be worth a look.

If you’re considering a pulper, first ask the manufacturer to work out a solid ROI. Most have calculation methods that take into account all kinds of variables including your garbage volume (this is the biggest factor) and mix, your trash hauling costs, water and sewer costs, what you pay for labor (analyzing time spent handling garbage), cost of can liners, cost of any fines cited for leaking or vermin-infested dumpsters, and more. The ROI is really the case-maker for any pulper purchase.

Close-Coupled Or Remote?

Pulpers’ two stages are either designed in a close-coupled configuration, with the grind chamber and liquid extractor together in the scrapping area, or the two are separated, with the grind chamber by scrapping and the extraction unit in a remote location, preferably near (or better yet, dispensing into) an industrial dumpster.

In a remote system, ground-up slurry (from one or several grind chambers) is pumped through pipes to that remotely located extractor. Traditional pulper models usually can accommodate a capacity of 900 lbs./hr. of garbage and go up as high as 1,250 lbs./hr. in a close-coupled unit, or up to 3,000 lbs./hr. in a remote system.

Heavy-duty pulpers are not small machines, so if space is at a premium, most makers offer those remote systems—but the cost of installation goes up substantially at that point. While most close-coupled systems will start around $35,000 to $40,000, some elaborately engineered remote systems can cost more than $100,000. But well-done remote systems that discard pulp directly into a dumpster can truly minimize garbage handling in your operation. You’ll still need to separately handle glass, metal, No. 10 cans, jar and bottle tops, and seafood shells. Mussels and clams, for instance, can grind to sand, which is hard on a pulper. Some manufacturers discourage plastic wrap and gloves, but not all.

One change in the engineering design of most pulpers has moved the grinding mechanism off the bottom of the grind chamber to the side wall. The grind chamber directs waste, including notoriously light Styrofoam (with its tendency to float) right into the grinding teeth. It’s not a very recent change, but you’ll find pulper operation is fairly simple, and design changes are rare.

Best Practices

Pulpers require little in the way of maintenance, but what little there is, is <I>critical<I>. A good, thorough cleaning once a day is absolutely mandatory; without it, the pulper will smell. Many models have hot water-flushing nozzles and automatic cleaning cycles to rinse the perforated screens around the extractor auger. Options include deodorizing units that dispense chemicals to help keep odors down, but nothing beats cleaning the unit per the manufacturer’s instructions. You should always let the unit run a little while longer after the load goes through, and cardboard, while not required, reportedly helps absorb odors, too.

Another must: make sure to order some sort of magnetic capture device to keep metal utensils out of the grind chamber. The manufacturers will recommend good options.

Kicking The Tires

While we don’t have the space to compare model to model from the seven pulper manufacturers who offer traditional units today (see sidebar), we can suggest questions to ask if a pulper is in your budget. First, you should know that, unlike many categories of equipment, pulpers come in very limited lines. At most, a company might offer 3 models, which differ by size or horsepower; most makers only produce one model of this dishroom workhorse.

What else should you look at? Check out the grinding mechanism, both the material of the cutters and the grind method. Grinders in the chamber are cast iron, hardened steel, or a carbide-tipped alloy, depending on the make. Manufacturers will espouse cutting blades or grinding plates—and it’s worthwhile to ask the manufacturer why it recommends one type of metal and processing action over another.

What is the cleaning process, realistically? “I don’t care what you hear about the simplicity of cleaning a pulper,” Young says. “You have to commit to the process and follow cleaning instructions to a T—it can take up to half an hour to do it right.” If your staff won’t do it, you might want to think twice about a pulper, he adds.

Finally, ask manufacturers for references. Find other healthcare facilities that are using pulpers to get an accurate picture of the benefits and responsibilities of the equipment.

Smaller Options

A crop of smaller waste handling options are on the market, which run in a price range from $16,000 to about $30,000. All three combine traditional <I>disposers<I> connected to liquid-extracting, auger/chute setups. They either fit under the dish table and take up no extra space in the kitchen, or they fit in about a quarter of the space of a full-size pulper.  

At first look, they’re a lower-cost, smaller-footprint, and lighter-duty alternative to a traditional pulper. These units are ideal if you’re a smaller operation or you’re in a municipality that bans regular disposer use. Each model can take a mix of food, paper and plastic, although not nearly to the extent of a full-size pulper. They excel on all-organic waste.

What’s really compelling about them is that they could prove an ideal option if your administration is pushing Green initiatives. Here’s why: by limiting what goes in the unit to organic waste, including food waste and truly compostable disposables (not all that claim to be are), you could develop a quick, convenient method of compostable capture.

The process will substantially reduce your waste volume (and the labor associated with getting rid of trash) and divert organic waste from the landfill—and that’s the prize. While composting infrastructure is still in its infancy, outlets accepting compost ingredients are growing rapidly in number (see www.findacomposter.com ).

GreenSpark Energy’s Liquid Waste Extractor (LWE) comprises a 2-hp (1.5kW) disposer, pump, and press that takes up about a quarter of the space of a traditional large pulper, but processes up to 500 lbs./hr. The auger on this unit spins at 1,500 rpm to achieve a centrifugally-powered liquid extraction, according to the company. The auger wheels are tipped with brushes to achieve continuous screen cleaning during operation and an automatic cleaning cycle kicks in as soon the machine is switched off. An optional spray hose further helps you keep the unit clean. A modular version of the LWE let’s you grind waste at the scrap table and pump/pipe the ground waste to a remotely located extractor.

InSinkErator’s Waste Xpress includes a 2-hp or 3-hp disposer and a water-flow control valve to use 3 gpm or 5 gpm. Kitchen waste, consisting mostly of food (the unit can handle up to 50 percent of nonfood items such as straws, jelly packs, Styrofoam, napkins, etc.) is ground into small particles in the disposer’s grind chamber. Ground waste travels to the dewatering unit where the waste is compressed, sending liquids down the drain and dispensing the solids through the chute into a 10-gal. trash can. With a twist of two turn-screws, the auger can be taken apart and put through a dishmachine for a thorough, 10-min. cleaning. Waste Xpress can process up to 700 lbs./hr.

Somat’s MP4, introduced at the NRA Show in 2010, combines its existing Hydra-Extractor with its own 5-hp Somat B-5 disposer, but it can connect to disposers made by other manufacturers, as well. That means it can retrofit if you’re already using a disposer. The MP4 has a ½ hp drive motor. Most of the water pressed through the auger screen is recirculated to the disposer. Somat designed the auger screen with smaller-than-usual hole sizes to achieve a quality gray water with fewer particulates. The MP4 processes up to 700 lbs./hr.

Whether yours is a large or small operation, pulpers and minipulpers can make quick work of garbage disposal and can reduce the chore of an unpleasant job right along with the volume of garbage your operation creates.

Pulper Manufacturers


Champion Industries

GreenSpark Energy Solutions (Disposer/Extractor)

Hobart Corp.

Insinger Machine Co.

InSinkErator (Disposer/Extractor)


National Conveyor Corp.

Somat Company (Pulpers & Disposer/Extractor)


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