Hailed as a miracle mineral because of its superior fire resistance and tensile strength, asbestos was installed abundantly into our built environment for over 200 years. However, once it was established that this undeniably useful resource was a dangerous carcinogen, Australia and many other countries enacted strict regulations for handling asbestos and asbestos containing material (ACM). There regulations created an asbestos abatement industry worth billions of dollars worldwide annually, and which will continue to generate millions of ton of asbestos waste long into the future.
Corporations and insurance companies have paid out billions of dollars in asbestos claims and have increased their reserves by billions of dollars to cover present and future incalculable loses pertaining to asbestos lawsuits. Much of the cement board that permeates Australian residential, commercial, school, and government buildings is a prominent example of such a product.
The installation and presence of these building products has caused many construction trade workers – including plumbers, pipefitters, boilermakers, carpenters and installers – to contract mesothelioma and other asbestos related diseases. Besides the construction trades, the people who live and work in buildings containing asbestos are potentially exposed to toxic forms of asbestos. Consequently, the ACM mining, manufacturing and installation industries have created great liability issues for the producers, installers, end users and their associated insurance companies.
From 1950 to 1970, Australia was the highest per capita user of asbestos in the world, and vast numbers of domestic dwellings built before 1982 contained – or still contain – asbestos.
Whereas most countries banned the use of asbestos in building products by 1980, Australia’s relatively late bans are likely to lead to more asbestos related exposures and diseases many years into the future. Australia already has one of the world’s highest rates of mesothelioma deaths, as well as many other asbestos related cancers. There late bans will feed the asbestos abatement industry and the disposal of asbestos and ACMs, as well as contribute strongly to ongoing contraction of asbestos diseases.
In Tasmania, the Australian Workers Union has developed a plan to remove all the ACM by 2030, 17 years from now. But this raises difficult questions. Will all ACM on substrates be removed? Where will the ACM be stored (nothing that asbestos never really goes away, even when landfilled).
US laws make the owner or generator asbestos or ACM a “Potential Responsible Part”, who is responsible for the cradle-to-grave liability for asbestos stored in a landfill through perpetuity. This means that when the landfill fails and must be cleaned up, the Potential Responsible Party or Parties, become responsible to pay for clean-up. In Australia there is no such regulation, with taxpayers meeting much of the financial burden for clean-up.
Let us explore the disposal options presently available for asbestos and ACMs.
Landfilling
Eventually, all landfills will fail. Modern day landfills liners last around 30 years. What happens when the liners are punctured or deteriorate?
Although landfilling is the cheapest and most convenient disposal option for asbestos or ACM, it is not the most cost effective – in the long run someone will have to pay to re-abate the asbestos from the landfill before it pollutes the surrounding area.
So what happens to asbestos or ACM when it is landfilled? By regulation, asbestos and ACM must be wrapped in plastic or a double polythene bag. Every package of asbestos must be clearly marked with a proper shipping name, including UN number, packaging group number, hazchem code and class label. The polythene bags are loaded on to a bin or trailer and driven to the landfill. The vehicle carting the ACM to the landfill must display a placard that is placed at the front and rear of the vehicle stating “Miscellaneous Dangerous Goods”. Next, the polythene bags are dumped from the height of a trailer or container into the landfill. The dumped asbestos polythene bags must then be covered with 15 to 30 cm of non-asbestos covering pushed over by heavy construction equipment.
What are the possible consequences of this method of disposal? Bags can break, allowing asbestos fibers to become airborne and migrate to the water table. An example of problems encountered in Australia with landfilling asbestos is Wyong Council’s landfill at Shelly Beach, New South Wales. Because ACMs have surfaced above its cover due to erosion and weather conditions, it will cost $12 million to clean up the asbestos dumped into the landfill during the 1970s. Also, there is no way to tell how many people who live and work around Shelly Beach have been exposed to the surfaced asbestos.
Thermal Options
There are presently three thermal options to destroy and permanently rid asbestos from our environment: vitrification, plasma torch, and Asbestos Recycling, Inc.’s hearth oven.
All thermal processes require high heat and high energy to destroy asbestos, because they need to run at 1500 to 2000 °C to glassify the asbestos. The asbestos is fed into the thermal unit for a required residence time. Following this, the end product must be cooled before testing. If no asbestos is detected by transmission electron microscopy, the end product can be recycled or sent to a non-regulated landfill. If asbestos is detected, then the whole previously treated batch must be put back through the thermal unit.
The high temperatures require substantial electricity at high cost, along with high maintenance costs on the refractory – the inner brick lining of furnace, which over time cracks and wears out due to the high temperature required to destroy the asbestos – which causes approximately 25 to 30% down time. Furthermore, the thermal unit must have an extensive and efficient scrubber system that prevents the escape of potentially harmful byproducts (e.g. furans, dioxins and nitrogen oxides).
Chemical Options
There are several chemical options for the permanent disposal for asbestos.
Soaking chrysotile asbestos in sulfuric acid for an extended period of time destroys the chrysotile, but is slow in its destruction reaction time. Once the reaction is complete, the acid is neutralized with a base, such as lime or baking soda.
W.R. Grace, Inc. developed an in situ non-thermal chemical process to destroy asbestos containing spray-on fireproofing containing chrysotile. The spray-on fireproofing (trade name Monokote) was developed and sold by Grace when asbestos was still permitted in building materials. When asbestos was banned, Grace developed an in situ chemical asbestos destruction process that destroyed only chrysotile. The process requires full negative air containment with four air changes per hour, but not high electrical use. Ultimately, Grace encountered two problems: 1) for a building with hundreds or thousands of square feet of sprayed-on fireproofing, it was difficult and costly to prove that all the asbestos was destroyed; 2) the process did not fall under the relevant US Federal Environmental Protection Agency (EPA) regulation; therefore Grace could not secure EPA approval for the process. (The aforementioned thermal options are EPA approved, because they do fall under the relevant regulation).
The ABCOV® Method of asbestos destruction is a non-thermal; EPA approved mixing process that chemically and physically destroys all forms of asbestos in all ACM. The process is performed under negative air containment and employs size reduction of the ACM and high speed dispersion mixing with ABCOV® chemicals, which are contained in a mild acidic solution.
The asbestos destruction is able to best tested, using polarized light microscopy, as the asbestos is being destroyed, allowing no asbestos to leave the process equipment until completely inert.
The process requires the negative air containment to have six air changes per hour. There is minimal electrical usage and a negative air scrubber system that includes an activated carbon filter and a high-efficiency particulate air filter that will provide six air changes per hour (as opposed to the four air changes per hour that is required for a typical asbestos abatement project performed under negative air containment.
Innovative waste treatment technologies are the future of the waste industry – not only for asbestos, but for all hazardous wastes that cannot be recycled.
Australian bans on asbestos:
1967 - crocidolite (blue asbestos) - considered the most dangerous of the asbestos minerals.
1989 - amosite (brown asbestos) - banned from building products (and from other products in 2003).
2003 - chrysotile (white asbestos).
2004 - the remaining asbestos minerals, tremolite, actinolite and anthophyllite.
Sources: Asbestos Disease Awareness Organization; Australian Council of Trade Unions
Further reading
- www.asbestos.com
- Asbestos Disease Awareness Organization (www.asbestosdiseaseawareness.org)
- United States Federal Environmental Protection Agency (www.epa.gov)
- Australian Industrial Waste Resource Guidelines: Asbestos Transport and Disposal (http://bit.ly/12EwRvY)
References
- NSW Government: Cabinet Office 2004. Report of the special commission of inquiry into the medical research and compensation foundation. ‘Asbestos and James Hardie’, Annexure J., p.117.
- National Occupational Health & Safety Commission 2005. Code of Practice for the Safe Removal of Asbestos 2nd Edition [NOHSC:2002 (2005)].
Disclaimer: Tony Nocito works for ABCOV®; Description of proprietary technologies does not imply endorsement by Remediation Australasia.
We would like to thank Australian Remediation Industry Cluster for giving us this great opportunity to publish our content in their quarterly magazine "Remediation Australasia." Remediation Australasia, Issue 13.
No comments:
Post a Comment