When it comes to waste collection, perhaps the biggest challenge is what to do with it. Add to that ongoing regulatory pressure, landfill closures, and longer hauls, and the cost of getting rid of waste continues to mount. Yet the hope for economy–and meeting mandated recovery levels–rests with MRF and transfer station operations.

By Joseph Lynn Tilton

One example of a successful waste collection operation is the Blue Bag program used by 750,000 Chicago, IL, households. "Residents of homes of four units or less are asked to put all recyclable materials in Blue Bags," explains John Kelly, a plant manager for Waste Management Inc., which operates four material recovery facilities (MRFs) for the city. "Plastics and aluminum cans are put in one bag, paper and fiber products in another Blue Bag, and all yardwaste in a third bag. It's a single stream, in a sense, because collection vehicles can pick up all solid waste in just one stop."

Kelly reports that this, along with pulling unbagged recyclables, makes possible a 25% diversion into the recycling stream. Screened material is utilized to help treat contaminated soils through a bioreaction process.

But it takes space to economically handle all this waste. Kelly's site is a 175,000-ft.² facility where 1,650 tpd are dumped on the tipping floor by 260 collection vehicles. "The waste is pushed into piles with a Caterpillar 980G front-end loader and then loaded onto two conveyors that move it into the processing stream for manual and mechanical sorting," he explains.

This plant employs roughly 170 in two shifts. Workers manually sort bulky materials, such as carpets, large pieces of steel, and wood. Then Blue Bag yardwaste and Blue Bag paper and plastic are pulled and sent to bunkers, where they're baled with HRB Harris balers and sold on the commodity market.

"The rest of the stream is sent through McLanahan rotating trommels, where everything between 2 and 9 inches is sorted out, including aluminum and ferrous material," describes Kelly. "The 9-inch-and-under material then goes through the Eriez system, which mechanically sorts material using screens, magnets, eddy currents, et cetera. What's left after that is end waste, which is transferred to the landfill."

Three maintenance crews of three to four work around the clock to keep downtime at a minimum. "When you're dealing with garbage, there are so many variables, plus safety is a constant concern. That's why we have daily meetings as well as signs and electronic boards," Kelly points out.

West Coast Operations

The Harris Amfab TP5000 is a 125-tph transfer station compactor.

Noting that the trend is toward single-streaming curbside collection, Sean Austin, sales manager for Bulk Handling systems in Eugene, OR, comments, "When you start saving money on the collection side, you have to invest on the MRF or transfer side. Five tons per hour is the limit for most nonmechanical separation, yet some MRFs get 40 to 50 tons per hour at their peak times. So automation is needed, and that investment in equipment can range anywhere from $50,000 to $2 million or so."

When it comes to deciding which pieces to add, Austin recommends looking at the maintenance history of the machine. "Look at how much time on a daily basis is needed for cleaning the machine. Thoroughly evaluate the quality of the components. Waste is abusive, so you want a machine that is well-built and rugged with heavy-duty bearings, heavy-duty motors, et cetera."

An operator also needs to understand the major components of his particular wastestream. "Commercial loads with 30% to 40% large cardboard and the rest in paper can be mechanically separated relatively easily because of the big disparity in size. If a load is all office paper, it's hard to gain efficiencies with mechanical separation because the elements of the load are the same size and shape."

Austin recommends including a conveyor that presorts material. "Large materials, such as pallets, should be removed before going into the conveyor, and you also want to remove plastic film and strapping because they tend to wrap around machinery parts and take longer to remove during the cleaning phase. Nylon stockings are tough on everything."

Kim Jaker, president and owner of H. West Equipment in Orange, CA, comments that longer hauling distances and scheduled landfill closures will become as real to Californians as rolling blackouts. "Here, recycling at transfer stations is critical. The size of transfer facilities must grow to accommodate further recycling.

"If you're just transferring solid waste, then a 20,000—square foot tipping floor can handle 1,000 tons per day. But it takes 60,000 to 80,000 square feet of floor space to handle 200 tons of recyclable material per day. You've got to make room for the equipment needed to recycle. You must have areas large enough to store materials in order to have an efficient run. For example, a wood processing area includes a wood shredder or hogger, but you shouldn't turn it on until you have 30 to 40 tons of material to run. The shredder can handle that in just a couple hours. So storage and tipping space is essential."

Jaker continues, "The drive is for machines that can handle more material in less time. In the last couple years, for example, material screens have come into broader use. These screens elevate and turn materials, allowing glass, dirt, and fines to be sorted out. Balers and sorting lines are faster and can process 20 to 25 tons per hour versus just 10 to 12 tons per hour a decade ago. And with more remote hauls, the need is to bale and compact waste to maximize trailer loads." At the same time, higher production demands require redundancy and reserve capacity to minimize downtime. When selecting equipment, reliability, high efficiency, and service support are the key elements.

Sizing for Need

The high-speed HRB Centurion balers can handle 20 tph of OCC.

Part of economically meeting the challenge of moving material is sizing the operation to the task at hand. Steve Viny, president of Norton Environmental in Independence, OH, notes that a MRF they operate in Medina County, OH, averages 500 tpd, while another MRF in Flagstaff, AZ, is designed for 80 tons. "Both are single-stream MRFs, but Medina, which has a landfill more than 60 miles away, gets raw MSW, recyclables, compostables, and fuel fractions. Recovered materials account for 35% of the Medina wastestream, with fuel fractions accounting for another 25%."

Fuel fractions include residual paper, business paper, envelopes, film plastics, and paper products that might be too soiled for traditional recycling yet still have heat value. "We're selling those products as a component but are looking to process in-house by late summer," Viny points out.

The Flagstaff plant is designed to handle recyclables only, and there is little contamination, thanks to a local landfill. "But both plants have safety and redundancy designed into their systems," he notes. "The waste business knows no holidays, and thanks to a stout design and excess capacity at both sites, neither facility has had to shut down.

"The key element is knowing what to specify and recognizing that the best bid isn't necessarily the lowest bid. The cheapest price is met by doing it right the first time." Viny adds that both plants have baling and sorting systems, but the Medina plant uses a large trommel, while Flagstaff uses a star screen. "The trommel is used to liberate a fine fraction as well as a sand screen to liberate those material from the MSW. The star screen is designed to separate round objects from flat. The flat objects are conveyed to a second sorting room where we're able to grade paper. The round objects go to the beverage container line where we automatically separate steel and aluminum, then into a sorting area where we grade plastic."

He points out that the Medina plant employs 80 people per shift while Flagstaff has but a dozen for each of the two shifts. "The difference is Flag accepts only recyclables, so we can have a little more automation. In Medina we have to be ready for anything that could be rubbish."

Noting the ongoing movement to single-stream recycling, Viny, who has been in the industry 24 years, concludes, "There's always going to be trash. By handling recyclables and trash at the same time, you can minimize or even eliminate the extra costs brought on by recycling."

Both Air and Screen

MRF sorting system

"The items of technology key to mechanical sorting are screens that separate different types of fiber, and air that separates light and heavy materials as well as broken glass from dirt and debris," reports John Willis, vice president of sales and marketing for CP Manufacturing in National City, CA. "Single-stream curbside recycling is the biggest trend I see in the marketplace today. Because it's easier than the old method of using different containers for different products, some cities are getting up to 50% more recycled materials."

Regarding qualities essential to screens, Willis recommends looking at the type of job the screens do. "On the news screen, does it capture 95% of the news? Does it minimize non-ONP [old news print]—acceptable material? Can it run the volume it's rated for, such as 20 tons per hour?

"Then compare maintenance costs of the equipment with the competition. For example, how long will the discs wear before they need to be replaced, and what is the cost for replacement on a continuous basis?" Ditto for container separators, seeking those that have minimal cross-contamination, that give the highest-quality end product at the lowest cost.

Willis continues, "Also, you need to look for a system that provides the lowest possible residue content, a system that minimizes the amount of recyclable material that gets thrown out with the residue. For example, if broken glass in residue accounts for up to 5% of your incoming stream, look for a system that separates broken glass and returns it as mixed broken glass. On the container line, look for systems that require the least amount of manpower."

Vibration is another element that helps sort the wastestream. "An important attribute of vibratory equipment is its ability to perform secondary operations, such as separation and classification, while moving material," remarks Bill Guptail, sales manager for General Kinematics Corporation in Barrington, IL. "Finger screens are adept at sorting commingled materials, such as paper or light plastic, and are often built into vibrating conveyors or feeders. They are normally used to perform an initial separation of incoming mixed bulk materials."

Guptail notes that vibratory equipment can provide a range of motion from aggressive tossing to smooth, gentle motion. "The frequency and amplitude of the ‘live' deck can be adjusted to classify, screen, align, or turn material while it's being moved through a MRF."

He adds, "A de-stoner/classifier is often used at the front end of a MRF to automatically pick or sort ‘heavies,' such as stones, bricks, glass, and ferrous metals, from the wastestream. Fines can also be separated from recyclable materials by finger screens that are normally incorporated within the de-stoner/classifier."

Adapting the Operation

Trommels like this are a sorting mainstay.

It's not unusual for a MRF or transfer station operator to inherit the physical plant. "A major challenge, as I see it, to bidding on contracts with municipal operations is you often have to adapt the operation to that environment," points out Peter Hess, corporate business manger for John Deere's Construction and Forestry Division in Moline, IL. "In a well-run operation you can follow a soup can in and out of a MRF or transfer station in an hour or two. I've seen operations with upward of five to six city trucks dumping on the floor at the same time. Then a four-wheel-drive frontloader, such as John Deere's 644H or 744H, pushes that material into a pile with a 6- to 7-yard bucket or directly into a landfill haul truck. If the truck is below floor level, it's a matter of pushing over the edge or over a 2-foot wall into the truck. If above floor level, then the load has to be lifted into the truck, which has a longer cycle time."

Hess adds that larger MRF operations will have six to nine different sort stations. "Every location, every setup is different, depending again on building structure and experience of the operators. Large or small, safety and maintenance are two main concerns with heavy equipment. Make sure the backup alarm is operational and the flashing yellow light works. When working in a tight environment, be aware of the walls, the people, and the pillars around you at all times. Watch that the steps into the machine don't get twisted or broken, and fix them if they do. Choose equipment with as many ground-level service points as possible to keep service easy and safe."

Also make certain that the cooling system is kept clean and that all key areas are protected. "There are lots of dangers to machines in a tipping floor. You have to beware of everything from pallets to ladies' nylons. Without proper guarding, maintenance costs will skyrocket and machine life will decrease. Stuff that gets in and around the fittings and hoses will accelerate wear and damage," warns Hess.

The 304H Waste Handler has a 1.4-yd. bucket.

After warning about the concern of exceeding rollover protective system certification weight limits with the added guarding and solid rubber tires from some manufacturers, he also counsels, "Shift maintenance should include removing anything sticking in the tire and cleaning out the cooling system along with the other original equipment manufacturer—recommended daily maintenance points. Just 15 to 25 minutes a day is usually sufficient for preventive maintenance."

Fernando Pellegrino, processing manger for Canadian Waste Services, agrees. His company operates seven collection sites in the greater Toronto, ON, area. Five are transfer stations with four to five employees each, while the MRF that Pellegrino operates has 15 employees. "One of our largest customers is Ford in Oakville, and we strive for a 90% recovery rate of their dry mix of cardboard, wood, and plastics.

"We have two types of transfer stations. One is run by compactors, which load into closed-top trailers; the other is run by a wheel loader loading into open-top trailers. When we design a compactor trailer scenario, we make sure the compactor blade is kept at least 8 to 10 inches above the [live] floor. If we get the blade any closer, the floor wears out quickly."

Pellegrino reports that both Universal and Titan trailers can withstand the compaction operation yet are light enough to maximize net weight capacity. "This makes possible 33 to 34 tons of maximum payload in a 48-foot trailer with six axles. All trash takes a 300-kilometer [185-mile] trip, while recyclables are picked up by receivers who are as close as an hour's drive from the MRF."

Pellegrino says his company inherited most of its sites, some with low ceilings. One answer to tight spaces is to rely on pressure gauges on the trailer's suspension instead of scales. "With pressure gauges and an experienced loader-operator, 85% to 90% of the loads will be right on for maximum loads."

Light material is a challenge, which Canadian Waste Services meets by having Caterpillar 322 excavators, which run over the garbage to break it up right on the receiving floor. "Our operation in Hamilton increased the net payload of light materials by an average of 2.5 to 3 tons per load by use of a Caterpillar compactor with Caron wheels."

But what about frozen loads? "The landfill operates a rod, which goes into the garbage, opens like an arrow tip, then is yanked out, pulling out a core of material. Then the [live] floor can do its work. We also spray calcium chloride inside the trailer before we load. Even though we avoid overnight storage in trailers, when it gets cold, a load will freeze in a 300-kilometer trip. It's part of life; we have to learn to work with frozen loads."

More Realities

What doesn't freeze, though, is the price for recyclables. Looking back over 16 years in the industry, Jim Jagou, vice president of sales for Harris Waste Management Group Inc. of Peachtree City, GA, comments, "Commodity prices are all over the map. I've seen corrugated as high as $200 per ton and as low as $5. Facilities that are profitable are making their money on the incoming waste through tipping fees and other charges for receiving material. They process, sort, package, and get it out to sell for a little extra."

As a baler manufacturer, Jagou notes that several elements play in the decision for buying a baler. "One concern is budget. The second is what products the operation is processing, and the third is what type of package is needed to satisfy the market. Today's balers are extremely versatile and can package almost anything you have to reduce in size to be able to transport and store. While glass is not baleable, paper, plastic, and metal generally can be baled in one form or another."

Balers are ideal for saving storage space. Jagou states that a bale measuring 45 x 30 x 60 in. will weigh around 1,100 lb. and can be equivalent to 30-40 yd. of loose material. "Every year balers get easier and easier to operate. Maintenance gets less and less because manufacturers are continuously finding new materials, new methods. This is a dynamic business with new developments in hydraulics and increased automation, and now–thanks to electronic technology–a baler is almost operator-free. Today's balers also give a lot of reporting functions, helping a user track the cost per bale, with power used, wire used, number of bales, and number of tons going right into his database."

Compactors are another essential element for economical waste management. Mitch Covington, marketing director for Marathon Equipment Company in Vernon, AL, observes, "In the past, compacting was done directly in the trailer, with as much as 40 tons of force during compaction. It took heavy-duty steel trailers to keep the material in place during compaction. Now, with the need for lighter trailers for high-net loads, the strategy is to compact the material before it's inserted into the trailer."

Covington points out that his firm's TS2000 extruder/compactor can handle 500 tpd and extrudes a log to a preset length, with 45 ft. typical. "Larger machines make a series of blocks, which are extruded one block at a time into the waiting trailer." Because of the abusive environment, durability is a major consideration.

Mobility is also important. "Contracts vary from one to five years, so if the contractor should lose the bid, he must be able to move his machine to another location," Covington says. Another concern is cleanliness of operation. "When a full trailer breaks away from the compactor, as much as 2 to 3 yards of garbage spills on the floor. Most operations don't clean up after every load, so by the end of day or week, there's a mess from repeated spills. With a good system, the compactor's ram pushes the load far enough in the trailer where breakaway spillage is minimum. In fact, the rear door can be closed before there's any spillage. This keeps the place cleaner and the municipal customers happier."

When You're Tight on Space

VersaHandlers can be used for moving paper and loading into a conveyor.

It's not uncommon for a MRF or transfer station to be tight on space. Martin Miller, VersaHandler product representative for Bobcat Company in Fargo, ND, says his machine is classified as a telescopic handler and a telescopic tool carrier. It can be fitted with buckets, grapples, sweepers, or augers. He points out that a MRF could use the machine for moving paper and loading into a conveyor. It can also be utilized in yardwaste operations, turning or loading mulch. "There's no tail swing with our 518 VersaHandler, and it can turn in a radius as small as 147 inches."

Also working with MRF operations is Myron Holzwarth of Wildcat Manufacturing in Freeman, SD. "Sizing of MRF operations is all over the board, from 1-acre to 80-plus-acre sites. Wildcat has over 30 models of compost turners and trommel screens to choose from, allowing us to tailor systems to a specific need.

"Successful MRF or transfer station operations that have composting as part of the operation tend to have compost turners and trommel screens. The two allow for a higher-quality finished product, something people will want to buy because there are no rocks, plastic, or twigs in the finished compost. Compost is here to stay because more and more cities are turning yardwaste into compost," Holzwarth concludes.

Therefore, by working together, contractors and manufacturers mitigate the solid waste challenge that is common to each and every community.

Joseph Lynn Tilton is a frequent contributor to MSW Management.