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Trash or treasure? Putting coal combustion waste to work.

Tenenbaum DJ - Environ. Health Perspect. (2009)

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Approximately 33% of the gypsum that was used to make U.S. wallboard in 2008 was FGD gypsum, says Michael Gardner, executive director of the Gypsum Association, a trade group, who adds, “Only cutbacks in construction due to the recession have prevented the use of even more FGD gypsum. ” The heat of coal combustion eliminates compounds such as dioxins and polycyclic aromatic hydrocarbons that could form during combustion, according to “PAHs and Dioxins Not Present in Fly Ash at Levels of Concern,” a presentation by Lisa Bradley and colleagues at the 2009 World of Coal Ash meeting, a biennial conference organized by the ACAA and the University of Kentucky Center for Applied Energy Research... Can they leach from construction materials as well? For safety purposes, LifeTime Composites tests fly ash before using it in its LifeTime Lumber product. “We do not want to run the risk of having a product that exceeds limits [for heavy metals] in our system,” says Mahler. “Our process encapsulates the ash [in polyurethane] to the point where no heavy metals are released in any way to humans, pets, or plants. ” At the 2007 World of Coal Ash meeting Liu reported on a test simulation of heavy rain at a construction site where Greenest Bricks were stored. “We compared the water sample to the EPA standard for drinking water, and every item—lead, selenium, and so on—was 10, 100, or 1,000 times less than the standard,” he says... Senior and colleagues published in the July 2009 issue of the Air & Waste Management Association’s EM magazine. “The wide variation in mercury loss (2 to 55%) from seven FGD gypsum samples [taken from five plants] was attributed to the different conditions under which each gypsum sample was generated,” the authors wrote. “Any remaining mercury in the finished FGD-wallboard could be released during use or subsequent disposal or recycling of the wallboard. ” The authors noted that research is under way at the EPA to evaluate the fate of mercury and other metals through each stage of wallboard’s life cycle... Heavy metals tend to stay put in conventional concrete, says Kosmatka, who cites a 2007 PCA-financed study of concrete that passed the EPA’s toxicity characteristic leaching procedure (TCLP) test despite containing cement carrying up to 0.1% lead, cadmium, and chromium... The study, titled Comparison of Mortar Leaching Methods, concluded that cement containing less than 500 mg/kg of these elements would even be usable in drinking water systems... Harold Walker, an associate professor of civil and environmental engineering at The Ohio State University, measured the release of airborne mercury while concrete containing fly ash cured for 28 days. “Less than 0.022% of the total quantity of mercury present from all mercury sources in the concrete was released during the curing process,” Walker and colleagues wrote in volume 23, issue 4 (2009) of Energy and Fuels, “and therefore, nearly all of the mercury was retained in the concrete. ” The authors noted that the addition of powdered activated carbon appeared to play an important role in reducing the total amount of mercury released... They also pointed out that their calculations did not address the potential release of mercury if the concrete were eventually crushed and landfilled... The degree of heavy metal leaching from highway applications “depends on the chemical character of the ash, the hydrologic setting, and whether the surface will be concrete or asphalt,” Benson says. “In almost all cases, the heavy metals get bound up with minerals after they move out of the CCW layer [and into soil or subsoil]. ” The EPA requirement that many electric generators remove mercury from their chimney emissions poses twin challenges for fly ash recycling... First, depending on the mercury removal technique used, the amount of mercury in the fly ash rises by up to 184 times, according to tests reported by Amy Dahl of Frontier GeoSciences at the 2008 MEGA Symposium, a meeting sponsored by the EPA, the Department of Energy, the Electric Power Research Institute, and the Air & Waste Management Association... Evans, a former EPA official who has testified before Congress in favor of some types of CCW recycling, favors a middle-ground option: designating the waste as hazardous when it is disposed but not when recycled into certain products, including cement and wallboard... Recycling can attenuate the overall greenhouse impact and the hazards associated with ash storage, but millions of tons of CCW are now put to “beneficial uses” that, absent adequate monitoring, raise environmental questions... Increased recycling may reduce more questionable forms of “beneficial use” along with the risks and environmental costs of waste disposal... Pounds takes another view: “The coal will be consumed to produce power regardless of the end use or designation of the [CCW]—and the challenge of replacing coal power with cleaner alternatives will remain urgent... The alternative—to simply landfill fly ash and to not take the significant environmental benefits from substituting fly ash for cement and other applications—would be irresponsible. ” Evans makes a similar point. “The increased disposal costs brought by national minimum standards for coal ash landfills and closure of unsafe coal ash impoundments will greatly increase the incentive for power plants to recycle, not dispose of the wastes,” she says. “Federal regulations that require greater scrutiny and monitoring of beneficial reuse applications will go a long way toward promoting safe recycling and eliminating the reuses that pose serious threats to health and the environment. ”

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Use of CCW in roadways1 EmbankmentTopsoil on roadside embankments can be amended with FGD materials if soil conditions permit. FGD materials can improve the condition of the soil, increase plant growth, and reduce runoff. Coal ash is suitable for embankment fill.2 Retaining wallRetaining walls hold back soil and rock and prevent the erosion of roadside slopes; they are often made of concrete or modular blocks. Fly ash can partially replace portland cement in concrete, making the concrete stronger and more durable. Portland cement also can contain FGD gypsum. Concrete aggregates can include bottom ash and recycled concrete, which may contain fly ash.3 Asphalt surfaceBoiler slag can replace virgin aggregate in the asphalt surface layer.4 Asphalt baseFly ash, bottom ash, and recycled concrete can be used as aggregate in the asphalt base layer.5 & 6 Granular base & sub-baseA variety of industrial materials can be used as granular base and sub-base, including bottom ash and recycled concrete. Fly ash also can be used as mineral filler in asphalt base, granular base, and sub-base.7 Subgrade (original soil)Fly ash can improve the structure and stability of the subgrade upon which the road will be built.8 Structural fillStructural fill supports and relieves pressure from retaining walls. Fly ash and recycled concrete can be used as backfill for retaining walls.9 Vegetated swaleVegetated swales provide drainage for roadways and help improve water quality. Recycled concrete can be used in place of traditional drainage materials, such as virgin sand or gravel.Adapted from U.S. EPA. Using recycled industrial materials in roadways. EPA-530-F-08-024. Washington, DC: U.S. Environmental Protection Agency; 2009: p. 2–3.
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f6-ehp-117-a490: Use of CCW in roadways1 EmbankmentTopsoil on roadside embankments can be amended with FGD materials if soil conditions permit. FGD materials can improve the condition of the soil, increase plant growth, and reduce runoff. Coal ash is suitable for embankment fill.2 Retaining wallRetaining walls hold back soil and rock and prevent the erosion of roadside slopes; they are often made of concrete or modular blocks. Fly ash can partially replace portland cement in concrete, making the concrete stronger and more durable. Portland cement also can contain FGD gypsum. Concrete aggregates can include bottom ash and recycled concrete, which may contain fly ash.3 Asphalt surfaceBoiler slag can replace virgin aggregate in the asphalt surface layer.4 Asphalt baseFly ash, bottom ash, and recycled concrete can be used as aggregate in the asphalt base layer.5 & 6 Granular base & sub-baseA variety of industrial materials can be used as granular base and sub-base, including bottom ash and recycled concrete. Fly ash also can be used as mineral filler in asphalt base, granular base, and sub-base.7 Subgrade (original soil)Fly ash can improve the structure and stability of the subgrade upon which the road will be built.8 Structural fillStructural fill supports and relieves pressure from retaining walls. Fly ash and recycled concrete can be used as backfill for retaining walls.9 Vegetated swaleVegetated swales provide drainage for roadways and help improve water quality. Recycled concrete can be used in place of traditional drainage materials, such as virgin sand or gravel.Adapted from U.S. EPA. Using recycled industrial materials in roadways. EPA-530-F-08-024. Washington, DC: U.S. Environmental Protection Agency; 2009: p. 2–3.


Trash or treasure? Putting coal combustion waste to work.

Tenenbaum DJ - Environ. Health Perspect. (2009)

Use of CCW in roadways1 EmbankmentTopsoil on roadside embankments can be amended with FGD materials if soil conditions permit. FGD materials can improve the condition of the soil, increase plant growth, and reduce runoff. Coal ash is suitable for embankment fill.2 Retaining wallRetaining walls hold back soil and rock and prevent the erosion of roadside slopes; they are often made of concrete or modular blocks. Fly ash can partially replace portland cement in concrete, making the concrete stronger and more durable. Portland cement also can contain FGD gypsum. Concrete aggregates can include bottom ash and recycled concrete, which may contain fly ash.3 Asphalt surfaceBoiler slag can replace virgin aggregate in the asphalt surface layer.4 Asphalt baseFly ash, bottom ash, and recycled concrete can be used as aggregate in the asphalt base layer.5 & 6 Granular base & sub-baseA variety of industrial materials can be used as granular base and sub-base, including bottom ash and recycled concrete. Fly ash also can be used as mineral filler in asphalt base, granular base, and sub-base.7 Subgrade (original soil)Fly ash can improve the structure and stability of the subgrade upon which the road will be built.8 Structural fillStructural fill supports and relieves pressure from retaining walls. Fly ash and recycled concrete can be used as backfill for retaining walls.9 Vegetated swaleVegetated swales provide drainage for roadways and help improve water quality. Recycled concrete can be used in place of traditional drainage materials, such as virgin sand or gravel.Adapted from U.S. EPA. Using recycled industrial materials in roadways. EPA-530-F-08-024. Washington, DC: U.S. Environmental Protection Agency; 2009: p. 2–3.
© Copyright Policy - public-domain
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC2801204&req=5

f6-ehp-117-a490: Use of CCW in roadways1 EmbankmentTopsoil on roadside embankments can be amended with FGD materials if soil conditions permit. FGD materials can improve the condition of the soil, increase plant growth, and reduce runoff. Coal ash is suitable for embankment fill.2 Retaining wallRetaining walls hold back soil and rock and prevent the erosion of roadside slopes; they are often made of concrete or modular blocks. Fly ash can partially replace portland cement in concrete, making the concrete stronger and more durable. Portland cement also can contain FGD gypsum. Concrete aggregates can include bottom ash and recycled concrete, which may contain fly ash.3 Asphalt surfaceBoiler slag can replace virgin aggregate in the asphalt surface layer.4 Asphalt baseFly ash, bottom ash, and recycled concrete can be used as aggregate in the asphalt base layer.5 & 6 Granular base & sub-baseA variety of industrial materials can be used as granular base and sub-base, including bottom ash and recycled concrete. Fly ash also can be used as mineral filler in asphalt base, granular base, and sub-base.7 Subgrade (original soil)Fly ash can improve the structure and stability of the subgrade upon which the road will be built.8 Structural fillStructural fill supports and relieves pressure from retaining walls. Fly ash and recycled concrete can be used as backfill for retaining walls.9 Vegetated swaleVegetated swales provide drainage for roadways and help improve water quality. Recycled concrete can be used in place of traditional drainage materials, such as virgin sand or gravel.Adapted from U.S. EPA. Using recycled industrial materials in roadways. EPA-530-F-08-024. Washington, DC: U.S. Environmental Protection Agency; 2009: p. 2–3.

View Article: PubMed Central - PubMed

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

Approximately 33% of the gypsum that was used to make U.S. wallboard in 2008 was FGD gypsum, says Michael Gardner, executive director of the Gypsum Association, a trade group, who adds, “Only cutbacks in construction due to the recession have prevented the use of even more FGD gypsum. ” The heat of coal combustion eliminates compounds such as dioxins and polycyclic aromatic hydrocarbons that could form during combustion, according to “PAHs and Dioxins Not Present in Fly Ash at Levels of Concern,” a presentation by Lisa Bradley and colleagues at the 2009 World of Coal Ash meeting, a biennial conference organized by the ACAA and the University of Kentucky Center for Applied Energy Research... Can they leach from construction materials as well? For safety purposes, LifeTime Composites tests fly ash before using it in its LifeTime Lumber product. “We do not want to run the risk of having a product that exceeds limits [for heavy metals] in our system,” says Mahler. “Our process encapsulates the ash [in polyurethane] to the point where no heavy metals are released in any way to humans, pets, or plants. ” At the 2007 World of Coal Ash meeting Liu reported on a test simulation of heavy rain at a construction site where Greenest Bricks were stored. “We compared the water sample to the EPA standard for drinking water, and every item—lead, selenium, and so on—was 10, 100, or 1,000 times less than the standard,” he says... Senior and colleagues published in the July 2009 issue of the Air & Waste Management Association’s EM magazine. “The wide variation in mercury loss (2 to 55%) from seven FGD gypsum samples [taken from five plants] was attributed to the different conditions under which each gypsum sample was generated,” the authors wrote. “Any remaining mercury in the finished FGD-wallboard could be released during use or subsequent disposal or recycling of the wallboard. ” The authors noted that research is under way at the EPA to evaluate the fate of mercury and other metals through each stage of wallboard’s life cycle... Heavy metals tend to stay put in conventional concrete, says Kosmatka, who cites a 2007 PCA-financed study of concrete that passed the EPA’s toxicity characteristic leaching procedure (TCLP) test despite containing cement carrying up to 0.1% lead, cadmium, and chromium... The study, titled Comparison of Mortar Leaching Methods, concluded that cement containing less than 500 mg/kg of these elements would even be usable in drinking water systems... Harold Walker, an associate professor of civil and environmental engineering at The Ohio State University, measured the release of airborne mercury while concrete containing fly ash cured for 28 days. “Less than 0.022% of the total quantity of mercury present from all mercury sources in the concrete was released during the curing process,” Walker and colleagues wrote in volume 23, issue 4 (2009) of Energy and Fuels, “and therefore, nearly all of the mercury was retained in the concrete. ” The authors noted that the addition of powdered activated carbon appeared to play an important role in reducing the total amount of mercury released... They also pointed out that their calculations did not address the potential release of mercury if the concrete were eventually crushed and landfilled... The degree of heavy metal leaching from highway applications “depends on the chemical character of the ash, the hydrologic setting, and whether the surface will be concrete or asphalt,” Benson says. “In almost all cases, the heavy metals get bound up with minerals after they move out of the CCW layer [and into soil or subsoil]. ” The EPA requirement that many electric generators remove mercury from their chimney emissions poses twin challenges for fly ash recycling... First, depending on the mercury removal technique used, the amount of mercury in the fly ash rises by up to 184 times, according to tests reported by Amy Dahl of Frontier GeoSciences at the 2008 MEGA Symposium, a meeting sponsored by the EPA, the Department of Energy, the Electric Power Research Institute, and the Air & Waste Management Association... Evans, a former EPA official who has testified before Congress in favor of some types of CCW recycling, favors a middle-ground option: designating the waste as hazardous when it is disposed but not when recycled into certain products, including cement and wallboard... Recycling can attenuate the overall greenhouse impact and the hazards associated with ash storage, but millions of tons of CCW are now put to “beneficial uses” that, absent adequate monitoring, raise environmental questions... Increased recycling may reduce more questionable forms of “beneficial use” along with the risks and environmental costs of waste disposal... Pounds takes another view: “The coal will be consumed to produce power regardless of the end use or designation of the [CCW]—and the challenge of replacing coal power with cleaner alternatives will remain urgent... The alternative—to simply landfill fly ash and to not take the significant environmental benefits from substituting fly ash for cement and other applications—would be irresponsible. ” Evans makes a similar point. “The increased disposal costs brought by national minimum standards for coal ash landfills and closure of unsafe coal ash impoundments will greatly increase the incentive for power plants to recycle, not dispose of the wastes,” she says. “Federal regulations that require greater scrutiny and monitoring of beneficial reuse applications will go a long way toward promoting safe recycling and eliminating the reuses that pose serious threats to health and the environment. ”

Show MeSH
Related in: MedlinePlus