Fast-Tracking Waste Reduction
By: Mike Sherer
To see a variety of disposers, pulpers and compactors, click here for the Waste Management Gallery.
As a kid, when your parents told you to take out the trash you probably threw it all into a big can and put it out at the curb, or tied it up in bags and took it to the dump. Now environmental concerns, economics and logistics make taking out the trash much more challenging.
Environmentally, trash is taking on greater significance as landfills close, regulations grow stricter concerning what you can and can't throw away, municipalities with aging sewer systems ban disposer use, and more localities emphasize or require recycling.
Economically, getting rid of what you don't want is increasingly expensive. Haulage and tipping fees are more costly as room in landfills grows scarcer and haulers' fuel costs rise.
Since your operations and the localities they're in aren't all the same, waste handling logistics can create headaches in some places and be a breeze in others. That means there's usually no cookie-cutter solution for waste management in all your stores.
Enough of the bad news. The good news is there are lots of options out there, and if you take a look at your operations and the unique waste management environment in the areas where they're located, you can put together waste handling plans that meet your needs, fit your operational philosophy and save you money.
What's Going Out?
The first step toward a sensible waste management program is figuring out what kind of trash you generate. You actually might be surprised by what ends up in your trash. Ideally, everything that comes in the back door of your restaurant would leave through the front door in the satisfied bellies of your customers.
Waste, however, occurs all through the "manufacturing" process of making food. First, there's the packaging the food arrives in. Next, there's food waste as raw products are prepped. In full-service restaurants, uneaten food comes back to the kitchen and has to go somewhere. In QSRs there's packaging for the food that you serve and food waste that customers toss on their way out.
Your waste stream obviously depends on your operation, customer volume, location and other factors. Full-service restaurants, for example, are likely to have more food waste; QSRs are likely to have more solid refuse like disposables.
Once you get a handle on what kind of waste you generate you can begin thinking about what to do with it. Recycling, for example, is a great way to help the environment and lower your waste handling costs. While it doesn't reduce the amount of trash you generate, recycling definitely reduces the amount of waste that goes straight into the Dumpster, reducing your tipping fees. Since most people are already familiar with the concept of separating paper, plastic, glass and metal for recycling, employee training is often minimal if you put out well-marked receptacles.
Composting is another way to reduce the amount of waste going directly into the trash while helping the environment at the same time. The San Francisco Marriott, for example, diverts more than 750,000 lbs. of compostable material a year to the city's composting program. The hotel's goal is 1 million lbs. a year. In some areas, noncommercial facilities such as universities and hospitals are setting up their own composting programs if the community doesn't offer one.
In terms of equipment, your options include disposers. Mounted below a sink, a garbage disposer grinds up food waste and flushes it into the sewer system with water. See our "Disposers Take On Food Waste" story below for details on technology and related issues.
Even if you use disposers, you still have to deal with the nonfood waste you generate. Read our story "Pulp Your Way To Less Waste" for info on pulpers, which can handle a variety of nonfood waste except glass and metal.
Finally, trash compactors are a way to greatly reduce your volume of trash that goes to the Dumpster and thus reduce tipping fees. We review compactors in "Make Mine Compact." So read on.
Disposers Take On Food Waste
We're all familiar with how a disposer works. Food wasteincluding some bones, depending on the size of the modelis pushed through the throat of the unit and into a grind chamber. There it is mixed with water to create slurry that gets sent down the drain.
While it's a straightforward, effective approach to waste reduction, disposer use has generated some questions over time, all of which suppliers have responded to with product updates and studies.
For example, traditionally disposers have been designed to take on only food waste. But on the product improvement side, at least one maker now offers disposers that can accept up to 50% volume of disposables as long as they're mixed in with food waste.
Occasionally someone will question water usage with disposers, and suppliers have that one covered, too. Most makers incorporate solenoid switches in their control packages that turn water on and off automatically whenever the disposer switch is turned on or off. This ensures that water isn't being used when the disposer isn't running.
In addition, one maker has a water-saving control that uses a load sensor in the grind chamber to determine whether the disposer has a full load of food waste. The system sends water into the grind chamber at about 1 gpm when it doesn't have a load, then opens a 7-gpm valve when it senses a load, increasing the flow to 8 gpm until all the food waste is flushed down the drain.
Disposer Bans: What's The Issue?
On the regulatory front, you may also have heard about a growing number of communities deciding to ban disposers due to aging sewer systems. Many municipalities now claim that the slurry produced by disposers is helping clog sewers and create overflows.
However, recent studies have shown that disposers are one of the most environmentally friendly means of food waste disposal and the least costly to municipalities compared to landfilling, composting or incinerating. A University of Wisconsin study in particular showed the cost to process the food waste in water treatment facilities is only a small fraction of the cost to handle it in other ways.
And in an interesting twist, some communities are now lifting disposer bans. In Raleigh, N.C., for example, the city council recently reversed a disposer ban that had been in effect only three weeks after learning that grease, debris, structural damage, tree roots and heavy rain were the top five contributors to sewer overflows there, not previously suspected food waste from disposers.
Sizing It Up
Commercial disposers are rated from ½-hp light-duty models all the way up to 10-hp monsters with hearty appetites. Horsepower, though, is only one way to determine what size you need.
Typically, manufacturers and consultants recommend disposer size based on number of meals served and the application. A disposer used in the dish room of a restaurant serving 300 to 500 meals a day should have about 1½ hp. A store serving 500 to 1,000 meals should have a 2-hp disposer; 1,000 to 2,000 meals calls for a 3-hp model; and so on. Disposers in salad prep areas could be lighter duty, ranging from ½ hp to 1½ hp, for example.
Throughput is another consideration, and the size of a disposer's throat and rotor or turntable have as great an effect here as horsepower. A larger throat means you can push more waste down at a time. A larger turntable means the disposer will grind a larger amount at a time.
Most manufacturers build their models with a single throat size. Typical of many machines is a 6½" or 6 5/8" throat to fit a 7" sink drain. At least one supplier builds disposer with a larger throat size of about 8¼" . Another offers disposers in two throat sizes, 4½" and 7" .
The bigger the rotor, the more waste it can handle at one time. Several suppliers build models around a single turntable size of about 8" , which is usually adequate for most operations. A couple of makers offer units with turntables ranging in size up to 15" , but the largest of these is designed to handle huge volume in institutional settings. However, some high-volume operations like hotels may benefit from models with larger-than-normal rotors.
Costs range from about $1,200 for light-duty prep-area units to $9,000 or more for heavy-duty models.
Pulp Your Way To Less Waste
Pulpers are two-stage machines that first grind all kinds of trash, except metal and glass, with water in a slurry chamber, then press most of the water out, leaving a semi-dry pulp. Suppliers claim the machines can reduce the volume of trash from 70% to 85%, and smaller models usually start at a capacity of 900 lbs./ hr.
Typically, grinders in the slurry chamber are tough stainless or tungsten alloy cutting blades or plates. Grind motors typically start at about 5 hp and go up from there. They can be mounted vertically or horizontally.
Dewatering is accomplished by pushing the ground-up trash through a cylindrical stainless screen with an auger. The water is forced through the screen and the auger pushes the pulp out a chute at the end of the cylinder. Auger motors are typically rated around 2 hp and up depending on the size of the machine. Again, both vertically mounted and horizontally mounted models are available, giving you some flexibility when it comes to space.
These aren't small machines, so if space is a problem, most makers offer remote systems. The slurry chamber and grinder are placed under the scrapping sink or trough as usual, but the slurry is piped to a remote dewatering device that you can place wherever you have more room, like in a garbage room off the loading dock.
Saving Water Through Recirculation
While you might think grinding up all that trash, especially nonfood items like disposables, requires vast quantities of water, pulpers actually can use less water than disposers. Most operate at about only 2 gpm because they recirculate the water that's pressed out of the trash. Since less water is sent down the drain, sewer costs also are lower.
You can put the pulp in the trash. However, if you purchase compostable disposables and train employees properly, you could send all the pulp from the machine to a composter and recycle almost everything else in the kitchen.
Pulpers require little in the way of maintenance. Simple cleaning once a day is usually all they need. Many models have flushing nozzles that automatically clean the mesh screens in the dewatering machine. Options include deodorizing units that dispense chemicals to help keep odors down.
The two concerns with pulpers are size and cost. At about $35,000, they're too expensive and too big for many restaurants, although a three-story chain restaurant in New York bought one when it found itself storing trash in a third-story walk-in to reduce odors in between garbage pickups. In general, though, high-volume hotels, cafeterias, casinos and similar operations will benefit most from what pulpers have to offer.
One manufacturer has tried to bridge the gap between disposers and pulpers by designing a smaller dewatering unit that can be mounted under a counter next to a heavy-duty disposer. Designed primarily for food waste, it will take up to 50% disposables and is available in two models rated at capacities of 500 lbs./hr. and 700 lbs./hr.
Make Mine Compact
The other way to reduce the volume of food and nonfood waste is to compact it. Trash compactors can reduce the volume of your trash by 50% up to a ratio of 25 to 1, depending on the type of trash. If your garbage consists of a high volume of food waste, compaction rates will be lower than if you're compacting trash that consists of a lot of air, such as cups and disposables.
Compactors come in a range of sizes for use both indoors and outdoors, so you can easily find one that meets your needs, and there are two types. One type uses a compaction plate to flatten trash inside a container. Smaller units may use an electrically operated screw to drive the compaction plate, while larger units typically use a hydraulic piston.
The other type of compactor uses an auger to compress trash as it forces it through a tube into a collection area.
Compacting Indoors Or Out
Indoor compactors can be placed in either the front of the house or the kitchen. Small units designed much like typical waste receptacles in fast food stores can sit in the dining area. They have sensors that automatically open the trash chute door when a customer gets near. Compaction cycles are automatic and as short as 12 secs. so customers don't have to wait.
These units can handle about 50 lbs. of waste, reducing the volume of most front-of-the-house waste by about 90%, say suppliers. Trash is compacted into heavy-duty plastic liners, preventing leaks of any liquids like soda or water. The liners are petroleum-based, not compostable like some can liners, so they're not as environmentally friendly. They're also more expensive than typical trash can liners, but you'll use fewer of them, and savings in tipping fees will far outweigh the added cost.
Operators say the units also save labor and waste handling costs because the units don't have to be emptied as often and the compacted trash requires smaller Dumpsters and fewer pickups. A Burger King in Bloomington, Minn., that installed one of the first units ever built says it reduced costs to $242 from $900 a month, saving nearly $95,000 in its first 12 years of use. Typical payback for these units is about 14 to 18 months.
Back-of-the-house indoor units are somewhat larger, with capacities of about 300 gals. up to 1,000 gals. of loose trash. They use plastic liners to prevent leaks, and they compact trash into wheeled bins to transport to a Dumpster.
Outdoor compactors come in a huge range of sizes. Smaller units typically hold from 4 cubic yards of compacted trash on up. Many of these smaller units are self-contained, meaning the trash is compacted directly into a trash container that your hauler can simply lift and empty. Many include features like a compaction plate that positions itself partway into the bin after a cycle, creating a seal that prevents odors and infestation by vermin and bugs.
To see a variety of disposers, pulpers and compactors, click here for the Waste Management Gallery.