Question

Study case about asbestos pollution and treatment by encapsulation please mention study region and everything .

Answer 1

Asbestos Pollution

Asbestos is the generic term given to several types of mineral fibers naturally occurring in 2 types of rock-forming minerals (serpentines and amphiboles). It is found in the form of long, fine fibers. There are extensive deposits in Russia, China, and South Africa. Asbestos' heat resistant and insulating properties have led to widespread use in pipe coverings, furnace insulation, brake linings, building insulation, fireproof clothing manufacture, cement, inert filler media, and many other applications.

Where does it come from?

Asbestos fibers may become liberated into the air via mining, milling, and processing of asbestos-containing products. Dumping of asbestos-containing wastes also contributes. In addition, releases occur as a result of maintenance work on asbestos-containing structures and equipment. Building demolition continues to be a major source.

How might it affect the environment?

Effects vary depending on the exact variety of asbestos in question. Generally speaking, scientific evidence suggests asbestos is a carcinogen and a cause of various bronchial conditions. It appears that asbestos does not tend to bind to the solids normally found in natural water systems; however, some materials (notably trace metals and organic compounds) have a tendency to bind to asbestos minerals. Asbestos is highly resistant to degradation via rotting, burning, chemical exposure, so it is very persistent in the environment.

Asbestos mainly affects the lungs and the membrane that surrounds the lungs and is a known human carcinogen by the inhalation route. There has been little convincing evidence of the carcinogenicity of ingested asbestos. Breathing high levels of asbestos fibers for a long time may result in scar-like tissue in the lungs resulting in a disease called asbestosis, usually found in workers exposed to asbestos, but not in the general public. The ability of asbestos to cause lung disease is because the fibers, once deposited in the deepest parts of the lung, remain in place for many years and may never be removed from the body. Effects vary depending on the variety of asbestos. The burden of asbestos-related disease continues to rise due to the long latency periods. No safe threshold for asbestos has been set by the WHO. In 1987, the International Agency for Research on Cancer classified asbestos as Group 1 compound, i.e. carcinogenic to humans (IARC, 1987). In 1998, the European Commission Scientific Committee on Toxicity, Ecotoxicity and the Environment (CSTEE) concluded that chrysotile is a proven carcinogen. In 2005, an independent risk assessment was undertaken in the European Community, which confirmed that all forms of inhaled asbestos can cause lung cancer, mesothelioma, and asbestosis and that there is no threshold level of exposure.

Treatment

Mechanochemical Treatment

Numerous industrial and experimental facilities have been set up, particularly in the last ten years, as a result of studies and researches on treating asbestos-containing waste (ACW) to stabilize it and to enable its reuse. Some of the stabilization processes reduce the hazards of ACW by imprisoning in a cement or resinoid matrix. Other processes modify the fibrous structure of asbestos and transform it into an inert substance. One such inactivation process is mechanochemical transformation. This new technology is extremely interesting both economically and industrially, especially in view of the European Directive 1999/3/CE of 24/4/99, which provides for the obligatory treatment of all types of waste material before its disposal.

Thermal Decomposition

Given the known carcinogenic effects, its wide occupational exposures and widespread use in the past, asbestos is considered a general health hazard and a priority treatment for pollution prevention. In this context, asbestos can be entirely transformed into a mixture of non-hazardous silicate phases throughout a thermal treatment at 1000–1250°C and to a silicate glass at T>1250°C. These products may be recycled for the production of traditional ceramics. In this paper we describe the recycle of thermally treated asbestos-containing materials as a raw material for glass ceramics and traditional ceramics. A significant improvement of the technological properties of porcelainized stoneware, obtained by high sintering of unglazed ceramic bodies, is accomplished by the addition of 5 wt% of asbestos-based glass-ceramic

Chemical Treatment

This study investigates the problems of degrading or otherwise altering through treatment with simple chemical reagents the fibers of chrysotile, the most common asbestos variety. The experiments conducted were aimed, on the one hand, at destroying the fibrous morphology by the chemical breakdown and, on the other, at nucleating and growing crystals (specifically anhydrite, CaSO₄) on fibers thus changing their dimensions. Degeneration runs contained mixtures of asbestos with different solution strengths of HCl, Na₂CO₃, and CO₂-saturated water. Of these, only the HCl runs showed appreciable fiber breakdown. The second sequence proved more successful in that anhydrite crystals were readily grown upon asbestos fibers. The applicability of experimental results to environmental control is considered.

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