UA5 C3 Liquid and Solid Emissions Obj 3.docx

Ash, in its various forms, is either waste or a re-usable, marketable product. The ultimate use of ash depends on its composition. This includes: Trace element concentrations of copper, lead, cadmium, arsenic, mercury, or others. Organic compounds such as dioxins, furans, and polycyclic aromatic hy...

Ash, in its various forms, is either waste or a re-usable, marketable product. The ultimate use of ash depends on its composition. This includes: Trace element concentrations of copper, lead, cadmium, arsenic, mercury, or others. Organic compounds such as dioxins, furans, and polycyclic aromatic hydrocarbons (PAHs). Waste ash may be disposed of in a dry state in landfills, or as a wet slurry in surface impoundments. A surface impoundment is simply a pond or lagoon built to store waste materials. Both landfills and surface impoundments must be built according to environmental regulations. They must be constructed in a manner to prevent contaminants from leaching into the groundwater. This is usually achieved by lining the impoundment with a low-permeability material such as heavy plastic or clay. Ash has many uses as a marketable product. Re-using ash is preferable to landfill disposal or containment methods. Below are some uses for fly ash. As an additive to Portland cement in the concrete industry As structural fill in road construction As soil amendment and fertilizer in agriculture d) Stucco Bottom ash particles are larger in size than fly ash. Bottom ash can be used as filler material in embankments, aggregate for road bases, and for traction control in snowy or icy environments. Coal-derived slag can be used as blasting grit for surface preparation and as a filler in asphalt. Flue gas desulfurization processes that remove sulfur compounds from flue gas also create marketable byproducts. Like ash, these byproducts may be sold or treated as waste. This is dependent on the process that produced the byproducts, the market value, and end user product specifications. The saleable products of the regenerable FGD process include elemental sulfur, sulfuric acid, and gypsum. Unfortunately, regenerable FGD is more costly to install and is therefore less common. For this reason, most FGD byproducts are diverted to waste disposal. FGD byproducts can be disposed either wet or dry. Again, surface impoundments or landfills are used. Dry landfill disposal is generally preferred because of its smaller volume and more options for reclamation.