November/December 1991
As landfill space disappears and tipping fees escalate in many parts of the country, the search intensifies for cost-effective recycling options for auto shredder residue.
By Kent Kiser
Kent Kiser is associate editor of Scrap Processing and Recycling.
Not too long ago, auto shredder operators could easily and inexpensively dispose of their auto shredder residue (ASR)--or fluff--in their local landfill and forget about it. In just a few years, however, the situation has changed. Landfill space is vanishing, particularly in the northeastern United States, Europe, and Japan. Also, tipping fees are skyrocketing, averaging $50 to $60 per ton in the Northeast, with a few locations charging as much as $100 per ton. In addition, states and federal agencies have heightened concern about the potentially hazardous nature of fluff and its environmental effects when disposed in a landfill.
Faced with this difficult scenario, shredder operators-particularly those in North America-have stepped up their efforts to find recycling options for the more than 3 million tons of ASR they generate per year, while also trying to keep up with the changing regulatory and legislative climate.
The Regulatory Obstacle Course
As if the landfill crunch weren't enough, the Environmental Protection Agency (EPA) scared the industry in September 1990 by implementing its Toxicity Characteristic Leaching Procedure (TCLP), which replaced the Extraction Procedure Toxicity test as the method for determining if a waste is hazardous due to toxicity. The TCLP threatened shredder operators by being potentially more aggressive in leaching certain metals such as lead and cadmium, which may be found in shredder fluff.
If a company's ASR filled the TCLP, the firm would be considered a "hazardous waste generator" and would have to abide by a litany of regulations. For example, the company would have to notify the EPA and get an identification number assigned to its processing site, or face fines up to $25,000 per day. If the facility stored, treated, or disposed of the fluff on-site, the operator would also have to obtain a permit from the EPA. If the material were hauled off-site, the firm could use only authorized hazardous waste transporters registered with the EPA. Furthermore, all shipments would have to be packaged and labeled in accordance with Department of Transportation regulations and would have to be accompanied by a Uniform Hazardous Waste Manifest. Finally, the material could only be sent to a disposal facility permitted, licensed, or authorized by the EPA or the state to accept hazardous waste. In essence, the TCLP has threatened to thrust shredder operators into the world of hazardous waste disposal and send their disposal costs through the roof, making auto recycling less profitable, even unprofitable.
Fortunately, most U.S. shredding companies have been able to avoid this noose by vigilantly monitoring the materials they process, implementing what the Institute of Scrap Recycling Industries (ISRI) (Washington, D.C.) calls “source-control measures." By inspecting for and removing multiple mufflers, batteries, gas tanks, cable ends, and waste from inbound scrap, shredder operators have been able to easily and consistently pass the TCLP. "If you can control your shredder feed on the input side, then in all probability your ASR will be OK," says Jay Zimmern, general manager of Prolerized Schiabo-Neu Co. (Jersey City, N.J.) and chairman of ReMA's shredders committee. By passing the TCLP test, he notes, most companies have been able to continue disposing their fluff in sanitary landfills.
Other not-so-bad news: The EPA, in its study titled "PCB, Lead, and Cadmium Levels in Shredder Waste Materials," found that only some--not all--shredding operations may generate fluff contaminated by these toxins above regulatory levels. "The potential risk depends on the constituent makeup of the fluff and the characteristics of the sites at which the fluff is generated or disposed, " the EPA noted in a memorandum. The agency acknowledged that due to the limited number of shredder sites sampled (seven) and the limited number of samples taken at each site, the study serves only as a preliminary assessment of potential contamination and the results “may not necessarily be representative of the shredder recycling industry as a whole."
Pending further study, the EPA recognized that "shredding operations that are well-managed and conducted in an environmentally sound manner provide valuable environmental benefits" and recommended that enforcement be focused only on shredding companies that pose "significant environmental problems." These efforts will likely focus on shredders located on or near environmentally sensitive areas, such as floodplains or aquifers, and on operations that have not adequately addressed issues related to blowing fluff, worker protection, and runoff. In the long run, the EPA may address the issue through the reauthorization of the Resource Conservation and Recovery Act or amend its regulations on polychlorinated biphenyls (PCBs) to authorize alternative disposal methods for fluff.
In August, ReMA submitted comments on the EPA's proposed rulemaking on the disposal of PCBs under Superfund, stressing that PCBs in shredder fluff are virtually immobile and, thus, are unlikely to leach in a landfill and pose a health threat. ReMA suggested developing management standards that would require the removal of PCB-containing capacitors from electrical products before such products are recycled and advocated the long-term goal of adopting a national Design for Recycling policy. In addition, the association said, the Superfund exemption that allows the landfilling of "small capacitors" should apply to fluff since most PCBs found in fluff come from pre-1979 small capacitors.
A Reprieve on the State Level?
Despite the challenges shredder operators are facing on the federal level, they are getting legislative relief in some states. For example, Texas passed a law that specifically permits the continued disposal of shredder fluff in municipal landfills, provided that the ASR contains no free liquids and has tested nonhazardous. The law also prohibits the sale of cars, white goods, or other products that have batteries, fuel tanks, or capacitors containing PCBs to a metal recycler unless the recycler has been informed of the presence of these components. Another Texas law exempts shredding operations from a rule that makes it a misdemeanor to mix used oil with solid waste destined for landfills.
Municipal landfill operators in Wisconsin are now permitted by law to use shredder fluff or foundry sand as a daily cover, provided that the shredder operator delivers the necessary quantity of fluff to the landfill daily or as specified, and that the landfill operator does not have a contract to use daily cover from another source.
In Tennessee, the councils of Nashville and Davidson counties passed an amendment that actually reduces landfill fees for wastes generated by recycling operations, including shredder fluff. And Virginia passed a law that would give permitting preference to new or expanding landfills if they agree to accept fluff and charge tipping fees for fluff that do not exceed those charged for municipal solid waste.
In California, the Department of Health Services passed an administrative rule that allows shredder operators to continue landfilling fluff provided it is treated, or encapsulated, with a polysilicate chemical to reduce the chance that it might leach hazardous constituents. These reprieves on the state level, however, have not deterred shredders from seeking long-term fluff recycling options.
Seeking Incineration Solutions
In the quest for ASR answers, researchers are finding that fluff can be its own worst enemy. The material is heterogeneous, including plastics, rubber, tramp metal, wood, wire, glass, carpet, oily fibers, and dirt--a mixture that precludes simple solutions. Also, the possible presence of potentially hazardous constituents such as lead, cadmium, PCBs, benzene, barium, zinc, and mercury can hinder or eliminate various recycling options.
One positive characteristic of ASR is its heating value, which has led many researchers to tout incineration as the answer. ASR has a heating value that ranges between 3,000 and 6,000 British thermal units (Btu) per pound, depending on the moisture and inorganic content. This value can be increased to 7,000 Btu or even 10,000 Btu through careful screening. Even then, fluff is not considered an ideal fuel because it is difficult to handle, high in ash, high in metals, and contains sulfur and chlorine, which form acids during combustion. But incineration is still attractive to many because it reportedly can generate usable energy from fluff, reduces fluff s volume up to 75 percent, and reduces its weight up to 50 percent. The major drawback of incineration, however, is that it is expensive.
For Ron Tabery, an engineer in Austin, Texas, the solution lies in a fluidized-bed incineration system coupled with energy recovery. The advantages of the fluidized-bed process, he says, are that it is insensitive to fuel quality; it controls emissions effectively; it offers high thermal efficiency using radiation, convection, and conduction; and it incinerates the combustibles while continuously removing the noncombustibles that sink to the bottom of the bed. The ash and emissions are said to be rendered environmentally benign by proprietary additives in the fluidized bed. The fly ash--the small, light particles--reportedly can be used as a cement extender, while the granular bottom ash can be used as an aggregate or in the cement and steel industries. "It could be that nothing will go to the landfill, which is the best of all scenarios," Tabery states.
Operating costs can be offset by recovering the energy generated and either using it to power the process or using the heat energy in another on-site industrial process, Tabery says, noting that the system's main economic benefits are in cost avoidance--reduced disposal costs and saved electricity expenses.
To reduce the capital costs of such a system, Tabery suggests establishing a large, regional operation to serve several shredders. The proximity of each shredder to the site is a concern, however, and Tabery wonders how easy it would be to promote cooperation between competing shredders. Permitting is another "Achilles' heel," he says, adding, "It can be done, but it will probably take a Year in permit preparation and negotiations with regulatory agencies." Perhaps the biggest hurdle, however, is persuading shredders to gamble on the technology. "It's a chicken-and-egg problem for fluidized-bed combustion," he explains. "There's nobody out there doing it with car fluff, and shredder operators are apprehensive about new technology, even if it is demonstrably better."
Midwest Associates (Cleveland) has taken a different tack. It has developed Skygas, a heat-based conversion process that reportedly converts up to 10 tons of ASR per hour into hydrogen and carbon monoxide gas, leaving minimal residue. The Skygas electrokinetic process is fed ASR mixed with moist sludge and other wastes, if available. Three carbon electrodes expose the mixture to 10,000-F heat, which gasifies the nonmetallic particles, the company says. The resulting "dirty gas" is sent to a second reactor to be cleaned. Carbon dioxide is reduced to carbon monoxide and tars are eliminated in a modified water-gas reaction. Carbon is added to the process at this stage in the form of coke and/or shredded tires.
The process runs on electricity, and the gas Produced reportedly can power turbines or diesel motors that produce electricity for the process, reducing the system's operating costs. The process produces six times more energy than it uses, Midwest says, and the residue can be vitrified for disposal or used as road aggregate.
The system operates at a cost of about $50 per ton, the company states, with equipment costs running approximately $3 million for the primary and secondary reactors and gas-cleaning equipment.
Addressing the Problem by Its Parts
Thomas Byro, ReMA director of special projects, is confident that half the solution lies in using the inorganic fluff elements, or "fines," in cement. The fines, which account for half the weight and 20 percent of the volume of shredder fluff, contain glass, sand, and oxidized metal, Byro says, and both silica sand--a component of glass--and oxidized iron are essential raw materials in the manufacture of cement.
Byro says that ball mills at a cement plant could crush the inorganics into a very fine material, which could be mixed with coal dust and blown into a cement kiln. The process would reduce the weight and volume of shredder fluff, provide an alternative to landfilling the inorganics, and enable cement makers to reduce their purchases of silica sand, hematite ore, and mill scale, he says. "Screening out the fines and inorganics is a tremendously wise first step,” says Tabery. Removing that material improves the heat value of the organics and reduces their potential toxicity level and the end weight of the ash, he says.
The Metal Scrap Research Foundation, an independent organization sponsored by ISRI, has hired Construction Technology Laboratories Inc. (Skokie, El.) to test Byro's proposal. Fluff fines will be substituted for sand and iron ore in making portland cement "clinker," the base material for cement. One-inch blocks will be made, and their setting time and strength will be checked. A TCLP test will also likely be conducted on the blocks. Meanwhile, TXI, a cement maker, and Chaparral Steel Co., both in Midlothian, Texas, are gearing up to conduct full-scale tests of the concept.
As for the organic portion of the fluff, Byro suggests pelletizing it with scrap paper, pulverized wooden pallets, or even corn cobs to make it bum better. The pellets, which would have a high heat value and a low sulfur content, could be sold to waste-to-energy plants, he says.
The organics could also be pyrolyzed to produce coal dust, a heavy oil, and a fuel gas, Byro believes. The dust could possibly be used in activated carbon products such as water filters, he notes, while the heavy oil could be sold to the lampblack industry or combined with the gas generated to power a turbine that generates electricity for on-site use. Microwave pyrolysis appears to be promising, Byro asserts, particularly if the iron-rich fluff fines can be separated beforehand, as in the cement making concept. Although microwaves can vaporize iron, the process is said to require prohibitive amounts of energy. If the iron elements are removed, Byro says, microwaves can reduce the organic portion of the fluff to a usable carbon char and oil.
Argonne National Laboratory (Argonne, Ill.) has also advanced a partial solution, which focuses on selectively dissolving and recovering the thermoplastics in ASR. Argonne's process reportedly reduces the fluff mass by 50 percent and its volume by 70 percent, while recovering clean polyurethane foam, a polypropylene and polyethylene mixture, a polyvinyl chloride and acrylonitrile-butadiene-styrene mixture, and iron oxides. The residual material remaining after the plastics have been extracted has a low chlorine content and could be made into solid fuel pellets, Argonne researchers claim.
Several issues remain to be addressed, however, including the processing costs, market value of the recovered plastics, and the hazardous content of the process streams. Several industry sources assert that this process would face serious permitting problems because it uses solvents that are considered "bad actors" by the EPA. Argonne says that 95 percent of the solvents can be extracted from the fluff before the pelletizing or disposal stage, but sources say that the residual 5 percent could render the fluff hazardous or less attractive as a fuel source.
A Government Solution?
Few shredder operators believe that any of the current proposed solutions will be a panacea for the entire problem, suggesting that perhaps the answer lies in a combination of processes. Still, shredding companies arc understandably reticent about investing in methods that are unproven in the field, Zimmern says. But time is running out, at least for firms in areas with vanishing landfill space. Shredder operators also realize that the volume of fluff, which now accounts for about 20 percent of a car's scrap weight, is likely to increase in the 1990s as automakers "lightweight" their new cars by replacing metal parts with plastics.
"I'm very concerned about the future of our industry," Zimmern says. “There may have to be a government solution, or recycling could come to a halt." Government must ask whether the advantages of recovering more than 14 million tons of metal from scrapped cars, white goods, and other steel products outweighs the disadvantages Of disposing of approximately 3 million tons of fluff. Or, as Zimmern says, "Is it better to dispose of 100 percent or 20 percent?"
Just how long will the industry have to wait for a solution? No one knows, but Zimmern says, "It could happen tomorrow." Then he adds, "It could happen in 10 years.”
An International Perspective
The shredder fluff crisis knows no international boundaries. Several European carmakers, in particular, have recognized the problem and taken steps to resolve it, forming joint ventures with other manufacturers.
German automaker Mercedes-Benz and Austrian steelmaker Voest-Alpine-Stahl AG are developing a natural-gas-fired steel smelter that would melt baled car hulks, making shredding unnecessary. In the proposed process, all fluids would be drained, engines would be removed and shredded separately from the body, and all batteries, catalytic converters, and copper-containing wires, motors, and cables would be dismantled. Then, all recyclable plastic parts would be removed.
The remaining hulk, including the tires and some plastics, would be baled and fed into the smelter. The plastics and other organics would reportedly combust and provide energy for the process, any heavy metals would enter the baghouse dust, and other residual materials would enter the slag, which could be used by the construction industry, the firms claim.
Unfortunately, it will be at least a year until a pilot plant is completed, and a production-capacity smelter would cost approximately $45 million, the companies say.
French automaker Peugeot has established a car recycling pilot plant in St. Pierre de Chandieu in cooperation with two other French firms--one a scrap processor, the other a cement producer. After cars are dismantled and shredded, the fluff is sent through several additional processing steps, including suctioning, magnetism/antimagnetism, and screening, to clean the material. The fluff is then treated to produce pellets that can reportedly be used as fuel for cement kilns or as a raw material in asphalt. At the end of the two-year pilot project, the firms will decide whether to implement the process on a larger scale. •
As landfill space disappears and tipping fees escalate in many parts of the country, the search intensifies for cost-effective recycling options for auto shredder residue.