NEWS FOCUS
EPA To Evaluate New Technologies For Cleaning Up Hazardous Waste Incineration and pyrolysis, fixation in unleachable matrices, and destruction by microorganisms will be demonstrated on Superfund wastes to help future users choose among alternative methods Stephen C. Stinson, C&EN New York
Government agencies and waste treatment companies have begun an ambitious program to rate costs and performances of new technologies to destroy or detoxify hazardous industrial wastes at sites around the country. Data reaped from this program will help future users choose among these technologies for full-scale, final destruction or neutralization of wastes on site. Congress ordered this evaluation program as part of the Comprehensive Environmental Response, Compensation & Liability Act of 1986, the law that reauthorized Superfund. The Environmental Protection Agency must choose and evaluate at least 10 such technologies each fiscal year. Although late passage of the law last year will prevent EPA from completing 10 evaluations in the current fiscal year, the agency will have several projects well under way, as well as a slate of 10 ready to go in fiscal 1988. This year's projects will include incineration and pyrolysis, fixation in unleachable matrices, and destruction by microorganisms. To qualify for the program, the technologies must already have passed pilot-plant tests. But current information about them is still insufficient to let users choose them with confidence for actual sites. In most cases, developer firms will pay full costs of transporting equipment to sites and operating it there. The most desirable technologies are those that can be used on site to destroy wastes and rebury detoxified soil and debris. EPA will pay for gathering data about costs and efficiencies and will publish reports about each evaluation. Demonstration sites are among those the agency considers especially dangerous to the public—the so-called Superfund sites. EPA has matched the capabilities of the technologies with the types of wastes and problems at each site. In the past, Superfund sites have been cleaned up by hauling away toxic wastes for incineration, land-
Plasma torch of Westinghouse Plasma Systems'pyrolysis unit atomizes liquid hazardous wastes May 25, 1987 C&EN
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Heavy contamination with pentachlorophenol and creosote on 2-acre site (left) of wood-treating company is reduced sharply after plowing and seeding with Detox Industries'microorganisms
filling, or simply depositing at another location. Congress has set a time limit on landfilling, however, because land available for landfills is now very limited. And transferring toxic wastes to another location only moves the problem without providing a final solution. As final solutions, some experts believe, incineration or pyrolysis is best for organic wastes. Moreover, several thermal destruction methods also incorporate toxic inorganic wastes into a slag. To the extent that the physical state of the slag and the chemical interactions within it render toxic inorganics completely unleachable, such materials may be safely buried at the site. Only long-term testing and observation of such slags at the site will reveal whether the leach-
Conveyor feeds contaminated soils, solids, or sludge to Westinghouse electricpyrolyzer 8
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ing problem finally has been solved. As for pyrolysis, such processes convert organic wastes into complex mixtures of other organic compounds. Some of these compounds may be carcinogenic or even more toxic than the originals. However, some of the newer pyrolysis technologies combust pyrolysis products completely to carbon dioxide, water, and harmless metal salts recovered from scrubbing stack gases. The advantage of such methods is that the volume of material to be incinerated at the end is kept to a minimum. However, problems could arise if potentially dangerous pyrolysis products are not completely destroyed. Immobilization of toxic wastes in cement or glassy materials seems best suited to inorganics. But some inventors of encapsulating processes have found ways to render even volatile solvents such as acetone unleachable or nonvolatile in matrices. As with other potential technologies, only a long period of time will tell whether this stabilizing solidification method solves or only postpones problems of toxic organic wastes. A major disadvantage of encapsulation is that the volume of the waste is increased because cement or glassy matrix is added to it. Some developers, however, may succeed in reducing the added encapsulant to a minimum. Another alternative technology for organic toxic wastes, microbial degradation, is an attractive solution because it can be thorough and requires less energy than some other methods. Such processes can take months, however. And microorganisms carefully engineered to detoxify target compounds like polychlorinated biphenyls (PCBs) or dibenzodioxins ("dioxins") in the laboratory may fail to do so in the complex environment of a contaminated site. However, some investigators have selected and bred naturally occurring microorganisms that destroy most organic wastes without being inhibited or killed by some of them. Also, it may be possible to design processes that separate microbiological reactions such
as dechlorination and complete oxidation into sequen tial steps. Two incineration technologies that EPA has select ed for demonstration in this year's Superfund innova tive technology evaluation (SITE) program are the circulating combustion bed system of Ogden Environ mental Services, San Diego, and the infrared incinera tor of Shirco Infrared Systems, Dallas. EPA has deter mined that the circulating combustion bed is suitable for treating the wastes at two California sites referred to as Stringfellow and McColl. The infrared incinera tor may be demonstrated at a site known as Rose Township in Michigan. EPA officials have not yet decided whether to use wastes from either or both the Stringfellow and McColl sites. In any case, wastes will be shipped to Ogden's pilot-plant combustor in La Jolla for test burns be cause Ogden has not yet completed mobile units that can be taken to the sites. The Stringfellow site is a canyon in the Arupa Mountains near Riverside (C&EN, May 27, 1985, page 11). It was used as a dump for industrial wastes from World War II until the early 1980s, when the pits there were capped. In addition to some five dozen organic compounds, a large amount of sulfuric acid, possibly from munitions production, was deposited at the site. Chemicals from the site have leached into the drinking water supplies of the nearby town of Glen Avon. Wells have been dug at the site to pump water up to an on-site treatment plant, which neutralizes the sulfuric acid with sodium hydroxide and purifies the water by passing it through charcoal. The McColl site, which borders both the Los Coy otes National Park and a golf course, is in Fullerton. Pits there were used to dump asphalt, tars, and drill ing muds from oil production and refining from 1942
until 1962. Some of the pits were covered with soil before 1960, when part of the golf course was built over them, and from 1968 to 1980, nearby land was developed for housing. In the 1970s, residents complained to state and fed eral authorities of odor and health problems. Pits containing drilling muds were capped in 1983. Today, three holes of the golf course are fenced off because tars have begun to seep up through the caps covering the pits there. Wastes from the Stringfellow and McColl sites seem ideal for demonstrating Ogden's circulating combus tion bed system. Injection of limestone might com pletely neutralize acidic gases from the sulfur content of McColl tars and the chlorinated organics and sulfu ric acid loading of Stringfellow wastes. In the combustor system, liquid, solid, and sludge wastes are fed into the bottom of a cyclone section of the unit, which agitates and sends them to the top of the combustion chamber. Wastes passing down the combustion tower meet a blast of air coming up. At the same time, powdered limestone is injected into the combustion chamber. The intense agitation produced by the combination of cyclone, air turbulence, and continuous recirculation back to the cyclone allows almost complete destruc tion of organics at temperatures as low as 1400 to 1600 °F. Residence times are two seconds for gases and as long as 30 minutes for solids. Gases pass through a heat exchanger, which recov ers heat to preheat combustion air. From there, gases are routed to a baghouse filter for removal of fly ash before being exhausted to the atmosphere. Detoxified solids are cooled after exit from the combustion chamber. Ogden spokesmen claim that because of the energy efficiency of low combustion temperatures and
College offers degrees in hazardous waste studies Responding to needs for trained peo ple in hazardous waste management, Findlay College in Findlay, Ohio, has established two- and four-year degree programs in hazardous waste studies. The two-year associate-in-arts degree prepares students for jobs as labora tory technicians or equipment opera tors at waste sites. The four-year B.S. degree, with options in physical or biological science, engineering, or accounting, prepares graduates for laboratory work, field supervisory as signments at waste sites, or graduate work in chemistry, biology, or engi neering. The 105-year-old liberal arts col lege founded the programs in partner ship with Ο. Η. Materials Corp., a local environmental services firm, which will
lend its laboratories and profession als for instruction. The company also will be one of several offering sum mer internships to students. Findlay will award 10 merit scholar ships of $1000 to new students. Other firms have set up more restricted schol arships, and college officials hope to secure support for all students in the programs. The associate degree curriculum lasts four semesters, along with one summer internship. Course work in cludes general and organic chemistry, introduction to hazardous wastes, tox icology, sampling techniques, physics, biology, geology, computer science, management, economics, and environ mental regulatory law. B.S. candidates will begin with the
same two years of course work. Courses in the last two years of the physical science option include quan titative, instrumental, and organic quali tative analysis; biochemistry; hydrolo gy; calculus; electronics; advanced toxi cology; and computer science. Students in the engineering option will take one year at Findlay beyond the basic two years, followed by two years in the engineering school of Washington University, St. Louis, or the University of Toledo. Additional courses at Findlay include advanced calculus, differential equations, and an alytical mechanics. Graduates will re ceive a B.S. degree in hazardous waste studies from Findlay and a B.S. de gree in engineering from Washington or Toledo.
May 25, 1987 C&EN
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Analysis: the touchstone of waste cleanup In the cleanup of any hazardous waste site, rigorous analytical chemical methods and meticulous record keeping lie at the heart of the project. Major analytical instrument makers such as Hewlett-Packard, Varian Associates, and Perkin-Elmer consult regularly with their chemist customers about how to use their instruments to perform federally mandated test procedures and manage the resulting flood of information. As Sabina Slavin of Perkin-Elmer points out, organic compounds are analyzed by various types of chromatography, including ion-trap detection and headspace gas chromatography. Inorganic components require some form of atomic spectroscopy, such as atomic absorption (AA), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), or ICP-mass spectrometry (ICP-MS). Slavin, who is manager of product marketing and planning, notes that lab-
oratories specializing in environmental testing are most likely to make the $200,000 investment that ICP-MS requires. This is because the technique combines the very low detection limits of an AA-graphite furnace with the 20 to 40 element-per-minute speeds of ICP-AES. These features help lab management handle the heavy sample traffic characteristic of environmental testing laboratories. These labs, as well as drug firms, are also among the most numerous users of laboratory information management systems (LIMS), Slavin says. Again, the computer-aided management of samples, storage and retrieval of analytical procedures, and generation of reports is useful for heavy sample traffic. LIMS also meets requirements of the Environmental Protection Agency for careful record keeping. Slavin recalls a classic case of the utility of Perkin-Elmer's LIMS system
preheating of combustion air, auxiliary fuels such as propane are not needed beyond startup, provided that the energy value of the waste exceeds 2900 Btu per lb. EPA scientists are particularly interested in the completeness of combustion and the lack of a need to scrub stack gases. The Michigan Rose Township site, where the Shirco mobile infrared incinerator may be demonstrated, has been the subject of cleanup efforts by the state's Department of Natural Resources since 1979. The department includes a division involved with environmental protection in addition to a division for managing public lands and parks as well as one for running fish and game programs. Rose Township was used as an illegal dump site during the 1960s and 1970s. After the state appropriated money to begin cleanup work at the site in 1979, investigators fbund about 1500 drums on the surface and 3500 more buried underground. Though the drums and 1500 tons of contaminated soil have been removed, more contaminated soil remains. Besides many chlorinated solvents, the soil contains 980 ppm of PCBs and 1400 ppm of lead in the form of sludge from paint manufacture. EPA scientists will be interested in measuring both the efficiency of incineration of organics and the possible immobilization of lead by fixation to soil in nonleachable form. Though there is natural skepticism about whether the lead will be truly unleachable, the possibility of proving that it is sparks interest in the Shirco process as a final solution to the problems at the Rose Township site. 10
May 25, 1987C&EN
in cleanup of the September 1982 derailment of 43 railroad cars that spilled 7 million lb of chemicals near Livingston, La. The Illinois Central Gulf Railroad hired IT Corp., an environmental services firm, to clean the site. Peggy Stewart, then director of IT field analytical services, arrived with a mobile laboratory to survey the site. Over the next several months, Stewart's crew of 25 worked three shifts a day, seven days a week, to do thousands of analyses monthly on samples from soil and 33 test wells. Transmission of data from remote terminals to the Perkin-Elmer 3200 superminicomputer at IT's Knoxville, Tenn., laboratory aided in building a three-dimensional map of the site. The map guided IT workers in their efforts to contain contamination and remove 70,000 tons of contaminated soil, enabling the railroad line to reopen in November 1983.
The incinerator uses a wire mesh conveyor belt to move up to 100 tons per day of size-graded solids to the primary furnace. There, rows of electrically powered silicon carbide rods provide temperatures of 1850 °F. Incinerated solids roll off the belt into a container. Gases from the primary furnace go to a gas-fired or infrared-heated secondary furnace for virtually complete combustion at 2300 °F. A scrubbing system tailored to the nature of the expected stack gases removes acidic substances before the gases are vented to the atmosphere. As with all sites to be considered for the SITE program, EPA will meet with local citizen groups and government bodies to inform them about the demonstration and invite public comment and participation before it does any work at Rose Township. Educational efforts will be carried out by EPA's Region 5, headquartered in Chicago. Yet another mode of thermal destruction to be demonstrated in the SITE program is pyrolysis. Westinghouse Electric Corp., Madison, Pa., has developed an electric pyrolyzer that interests EPA scientists, though no site has been chosen for a demonstration. The pyrolyzer can be used to treat soils, solids, wastes, and sludges. The reaction chamber of the Westinghouse electric pyrolyzer is heated to 3000 °F by heating elements in the ceiling that are analogous to the broiling elements in a household electric oven. At these temperatures, organic components are atomized, while solids form a vitreous melt floating on top of any melted metal. Fine solids entrained in pyrolysis gases are captured
in a baghouse filter and recirculated to the reaction Two more technologies to be demonstrated in EPA's chamber. Scrubbing removes hydrogen chloride and SITE program involve immobilization of undestroyed sulfide from gases, which are then flared. Molten wastes by encapsulation. One such technology is that metal and slag are drawn off at separate taps and of Hazcon, Brookshire, Tex., and may be demonstrated allowed to solidify. at a site at Douglassville, Pa. The other immobilizaIt is possible that toxic metals and inorganic comtion technology was developed by Japan National pounds will be immobilized by entrapment in metal Railways and Sanwa Kizai Co. and licensed to Interand glass, thus making these solids more safely disnational Waste Technology, Wichita, Kan. Demonstraposable than otherwise. As always, careful testing and tion of that system may take place at a General Electric long-term observation will be needed to verify that Co. site in Hialeah, Fla. toxic substances are indeed immobilized. The Douglassville site is actually across the Schuylkill Meanwhile, the New York State Department of EnRiver from that city in Union Township. From 1941 v i r o n m e n t a l Conservation has b o u g h t a plasma on, a waste oil recycling company used it to dispose of pyrolyzer from a Canadian firm called Pyrolysis Syswastes by landfilling. The site received waste oil tems, and it plans to demonstrate this unit on wastes sludges, filter cakes from other processes, and drums at Love Canal. The equipment was built around a of waste oil. At present, the site contains 300,000 cu Westinghouse plasma torch. Pyrolysis Systems has since yd of soil contaminated with polynuclear aromatic formed a joint venture company called Westinghouse hydrocarbons, PCBs, lead, benzene, and trichloroPlasma Systems to produce more plasma pyrolyzers. ethylene. Wells drilled at Love Canal have been pumping Hazcon has developed proprietary additives that, accumulated underground water to be treated. Oils when added to cement, interact with organic and heavier than water have been separated from the inorganic components of industrial waste to render water and stored on site. It is these oils, containing them compatible with the cement. The company's 300 components including dioxins and many chlorimobile units will journey to whatever site is selected, nated organics, that will be destroyed in the plasma mix the cement, blend the wastes with the cement, pyrolyzer. cast the cement composite into blocks, and bury the blocks on site. Unlike the electric pyrolyzer, the plasma pyrolyzer is limited to destruction of liquid wastes. It uses 750 According to Hazcon s p o k e s m e n , two to t h r e e kW of electricity to produce an arc to ignite the plasparts of waste by volume may be blended with one ma. Methanol is used in the startup, and liquid waste part of cement, thus minimizing the amount of volis introduced 15 minutes later, when temperatures ume added. In a worst case, they say, the ratio is one have stabilized at 2200 °F. to one. Temperatures eventually reach 27,000 °F, atomizing Hazcon representatives say that volatile solvents the liquid. The pyrolysis products are 40% hydrogen, such as acetone are nonleachable, that blocks made 25% carbon monoxide, 15% nitrogen, and 10% water, from these solvents are capable of being deposited in together with chlorine and low-molecular-weight hya landfill, and that they have a compressive strength drocarbons such as methane and ethane. Chlorine of more than 1200 psi. Even petroleum refining separeacts with hydrogen to generate hydrogen chloride, which is scrubbed from pyrolysis gases with sodium hydroxide. Scrubbed pyrolysis gases are burned in a flare. The heat from the pyrolysis gases can be recovered for such purposes as steam generation. Heat recovery is practical only for stationary, permanent installations, however, and will not be attempted with the demonstration of the mobile unit at Love Canal. EPA's Region 2, headquartered in New York City, is expected to help with educational efforts at Love Canal to inform local citizen groups and government bodies about the demonstration of the plasma pyrolyzer. However, spokesmen for the state agency note that it is the lead agency in the program, and that it has conducted community relations at Love CaPCB-contaminated waste oil in tank is treated with Detox Industries' nal for many years. microorganisms in adjacent fermentation tank May 25, 1987 C&EN
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Hazcon Inc.'s mobile equipment (left) mixes toxic waste with cement and makes it into blocks. Dark form (above) is used for casting, white block has stood outside for one year rator sludge can be immobilized in cement blocks with compressive strengths of 100 psi. Hazcon has observed blocks of immobilized waste outdoors for a year. It has seen no evidence of cracking, weathering, or leaching. EPA scientists will be interested in seeing whether the blocks at the demonstration site are unleachable over the long term. The immobilization technology of International Waste Technologies to be demonstrated at the Hialeah site also involves proprietary chemicals that are either injected into contaminated soil in situ or blended with the soil in a cement mixer. For every pound of soil to be immobilized, 0.15 lb of dry chemicals is slurried with water. The additives polymerize to bind toxic substances to the soil, rendering them nonleachable. The chemi-
Hazcon technician mixes cement with proprietary additives and toxic waste and casts a block of it 12
May 25, 1987 C&EN
cals also dechlorinate organics. Treated soil takes one to four weeks to set. The Douglassville project cannot be started until EPA's Region 3, headquartered in Philadelphia, undertakes public educational efforts. The Hialeah site was a General Electric repair shop that accepted transformers and capacitors containing PCB dielectric fluids. PCBs contaminated 15,000 sq ft of soil to an average depth of 17 ft. In-situ injection will be used to apply the chemicals to be used there. As with the other demonstrations, the project cannot be carried out until successful public educational programs are completed by EPA's Region 4, based in Atlanta. The microbiological technology to be demonstrated in EPA's SITE program is that of Detox Industries, Sugar Land, Tex. The location of the demonstration may be the now-abandoned site of United Creosoting Co., Conroe, Tex. Ground there is contaminated with pentachlorophenol and creosote used in treatment of wood from 1946 to 1972. Beginning in 1977, the land was redeveloped for housing and commercial property. Now 13,000 people live within 2 miles of the site, and local businesses operate facilities there. Detox Industries has selected and bred a bank of 200 naturally occurring, nonpathogenic, soil microorganisms for particular waste-destroying capabilities. For unoccupied flat land that is contaminated at only shallow depths, Detox injects the microorganisms with nutrients into the ground. In builtup areas and in narrow areas of deep contamination, Detox excavates soil, slurries it with water in a tank, adds microorganisms and nutrients, and agitates the tank. Detox also has used the tank process to destroy waste oil together with the PCBs it contained. Both processes require a few months for total destruction of organic compounds. The company proposes a demonstration of tank fermentation at United Creosoting. Community relations people at EPA's Region 6, headquartered in Dallas, will inform local citizen groups and government bodies about the demonstration and ask for public comment. D
