Taking the bite out of asbestos toxins.
Asbestos was once called the "magic mineral" for its excellent fire and chemical resistant properties. It is these properties which have resisted attempts by scientists to develop a cost-effective method to detoxify asbestos. Through new adaptations of well-known technologies of asbestos abatement, the conversion of asbestos into a completely asbestos-free material is now possible.
The making of asbestos-free, glass-like aggregate from asbestos-containing waste material (ACWM) through the use of a variety of thermal conversion processes has been demonstrated and verified by the Environmental Protection Agency. A small number of companies are now classified by the EPA as recycling facilities and are using this thermal conversion process of asbestos to produce saleable byproducts and eliminate any waste streams.
Asbestos naturally contains the key elements necessary to make glass. When exposed to temperatures over 2,000 [degrees] F, its needle-like structure breaks down to form a nonhazardous gas. As a result, the liability of future exposures related to landfill contamination are completely eliminated.
Vitrification has recently emerged as one of the most popular methods of converting asbestos fibers into glass. This process is a modification of present glassmaking technology and utilizes very high temperatures to melt and detoxify the asbestos fibers. Vitrification permanently alters both the physical and chemical structure of asbestos, converting it into a glass-like aggregate. This process, like most other thermal conversion systems, utilizes glass technology combined with innovative waste processing devices to detoxify asbestos-containing waste material into asbestos-free material.
As alternative to the thermal conversion methods, several asbestos fixation or encapsulation techniques have also been attempted. These methods involve binding the asbestos fibers with portland cement, epoxy, or other acid, thermal and/or pressure systems to create a nonfriable matrix. The resultant material, although less bulky, is significantly heavier and may still have to be disposed of. Care must be taken to avoid the erosion or abrasion of the material to prevent future exposure to the asbestos fibers bound in the matrix. In the final analysis, this encapsulated material still contains all the original asbestos and all the waste liability.
Several new asbestos abatement processes utilize technologies proven in research and pilot plants. The more comprehensive technologies usually include an innovative marriage of existing glassmaking, hazardous waste management and air pollution control technologies. These processes must be intrinsically reliable and designed with a systems safety approach.
The thermal conversion processing area must be specially designed for maximum cleanliness and environmental safety. Such a facility will receive ACWM in large, sealed roll-off containers. The material will be automatically and safely conveyed through an isolated charging system with the storage bags unopened. The area in which asbestos waste is unloaded and stored is maintained under subatmospheric air pressure, as is the thermal processor.
State-of-the-art technology and system safety analysis must be employed at all times to make these thermal processes intrinsically safe and reliable. All operations must be supervised by carefully selected and properly trained employees in accordance with stringent operating procedures. Glass byproducts must be subjected to rigorous internal quality assurance protocols and periodically tested via independent certified consultants to insure that the process is complete.
Air Pollution Control
Air pollution control (APC) systems typically feature dual secondary stage filtration, which includes a high efficiency particulate air (HEPA) filter array downstream of the fabric filters. This ensures a very high capture rate of particulates within the area undergoing conversion. If the system is designed to EPA-defined best available control technology (BACT), their will be virtually no significant particle emissions and such a system may not even need an exhaust stack. It is desirable to have all the sludge and gatherings from the APC returned to the thermal processor to be transformed into aggregate so that there is no waste discharge from the plant.
Asbestos Exposure Control
The phase transformation process must be engineered to prevent any hazardous emissions during processing. The feed mechanisms must be carefully designed to prevent employee exposure to asbestos during the automated loading of the furnace. There is no pretreatment, shredding, sorting, or opening of the bags or containers in any part of the process.
Containerized asbestos waste must be completely controlled from the time the facility receives the ACWM to the time an asbestos-free aggregate is produced. All loads of ACWM must be fully inspected to assure National Emission Standards for Hazardous Air Pollutants (NESHAP) and Department of Transportation conformance. Transporter licenses and certificates of insurance must be components of a facilities standard operations procedure and that procedure should be designed to parallel the high standards and recordkeeping required in pharmaceutical manufacturing.
Environmental technicians should perform all the necessary quality assurance tests and monitor the execution of all safety procedures on a round-the-clock basis. All interior and exterior air monitoring should be conducted under the supervision of a certified industrial hygienist (CIH). In addition, professional independent air monitoring should be conducted periodically to validate the results of all internal quality assurance procedures.
The conversion of ACWM in the vitrification unit is virtually immediate. Once quality assurance testing and documentation have been completed on an individual load of waste material, a certificate of detoxification, or similar document, should be issued by the detoxification facility giving proof of the complete absence of asbestos in the glass-like aggregate products. The building owner's future waste liability would then be virtually eliminated.
The EPA has worked diligently to evaluate these new asbestos detoxification technologies and develop stringent protocols assuring the efficiency and environmental safety of any asbestos detoxification facility. In January 1989, the final revisions to the NESHAP were published. The previous NESHAP standard allowed protocols of only solid waste landfills for asbestos-containing waste material disposal. These revised standards now allow the EPA regional administrator to approve permits for facilities that detoxify asbestos-containing waste.
Asbestos-containing waste material is highly variable in nature and may contain widely varying proportions of asbestos and other abatement and demolition debris. It is, therefore, essential that any detoxification process be capable of safely processing, in an intrinsically reliable manner, all ACWM into 100 percent asbestos-free material. The EPA has mandated strict permit standards to assure the safety of the operations and the surrounding environment of all licensed facilities. The key element in the issuance of a permit to any such facility is validation that their process is reliable. These licensed facilities must also provide a method of independent certified laboratory validation of the 100 percent conversion of all ACWM processed.
Compliance with the NESHAP is required for all licensed facilities. Stringent procedures and protocols must be submitted by parties seeking to construct and operate a detoxification facility to federal, state, and local regulatory agencies in order to assure full conformance to all regulatory requirements prior to issue of a permit.
There must be a chain-of-custody record identifying the building owner and operator. That record should include all other responsible entities involved in the asbestos abatement project such as the generator of the waste and the licensed transporter who carts the material to the detoxification facility. The contractors must provide the name, address and telephone number of the laboratory or consultant who will inspect the ACWM handling practices during abatement and transportation. Each individual ACWM load must be tracked and typically handled on a first-in first-out basis.
Specialty insurance markets have responded very favorably to the potential implementation of these new detoxification technologies. As a result of state-of-the-art engineering and rigorous quality assurance programs, comprehensive insurance coverage for such detoxification facilities can be placed through specialty markets. A number of providers of asbestos related liability coverage have indicated their early support of these technologies and anticipate providing appropriate limits of pollution legal liability coverage.
To date, no asbestos detoxification technologies have been successful on a commercial basis. However, there is reason to believe that more ACWM detoxification technologies will be available early in 1990. And with these new technologies there is the expectation that asbestos waste liability exposures will soon disappear forever.
PHOTO : Schematic drawing of an asbestos detoxification unit used for the thermal conversion of
PHOTO : asbestos fibers into a nontoxic glass-like aggregate.
Lawrence G. Wylie is president of Omega Phase Transformations, Inc. in Narberth, PA.
|Printer friendly Cite/link Email Feedback|
|Author:||Wylie, Lawrence G.|
|Date:||Aug 1, 1989|
|Previous Article:||Technology meets new environmental challenges.|
|Next Article:||Asbestos abatement begins with comprehensive safety procedures.|