Generation of Solid Wastes

Oxygen-blown gasification has a carbon conversion of 98 to 99.9+%, which is higher than that (90 to 95% carbon conversion) for the air-blown case. This leads to less generation of solid waste (ash or slag). 

If coal or oil is the fuel source, the FGD control technologies result in the generation of solid wastes. Wet lime/limestone scrubbers produce a slurry of ash, unreacted lime, calcium sulfate, and calcium sulfite. Dry scrubber systems produce a mixture of unreacted sorbent (e.g., lime, limestone, sodium carbonates, and calcium carbonates), sulfur salts, and fly ash. 

Functional Elements The activities associated with the management of solid wastes from the point of generation to final disposal have been grouped into the functional elements identified in Fig. 25-59. By considering each fundamental element separately, it is possible to (1) identify the fundamental element and (2) develop, when possible, quantifiable relationships for the purpose of making engineering comparisons, analyses, and evaluations. 

Sohd wastes, as noted previously, include all sohd or semisolid materials that are no longer considered of sufficient value to be retained in a given setting. The types and sources of solid wastes, the physical and chemical composition of sohd wastes, and typical solid-waste generation rates are considered in this subsection. 

Types of Solid Wastes The term solid wastes is aU-inchisive and encompasses all sources, types of classifications, compositions, and properties. As a basis for subsequent discussions, it will be helpful to define the various types of solid wastes that are generated. It is important to note that the definitions of solid-waste terms and the classifications vary greatly in prac tice and in literature. Consequently, the use of published data requires considerable care, judgment, and common sense. The following definitions are intended to serve as a guide. 

Quantities of Solid Wastes Representative data on the quantities of sohd wastes and factors affecting the generation rates are considered briefly in the following paragraphs. 

Manual Component Separation The manual separation of solid-waste components can be accomplished at the source where solid wastes are generated, at a transfer station, at a centralized processing station, or at the disposal site. Manual sorting at the source of generation is the most positive way to achieve the recoveiy and reuse of materials. The number and types of components salvaged or sorted (e.g., cardboard and high-quality paper, metals, and wood) depend on the location, the opportunities for recycling, and the resale market. There has been an evolution in the solid waste indus-tiy to combine manual and automatic separation techniques to reduce overall costs and produce a cleaner product, especially for recyclable materials. 

Can they provide a list of solid wastes generated from operations within the past year ... 

In the United States, the Resource Conservation and Recovery Act of 1976 (RCRA) is the major legislation covering the disposal of solid and hazardous wastes (2). This act provides a multifaceted approach to solving the problems associated with the generation of approximately 5 billion metric tons of solid waste each year in the United States. It places particular emphasis on the regulation of hazardous wastes. This law established the Office of Solid Waste within the Environmental Protection Agency and directed the agency to publish hazardous waste characteristics and criteria. 

Landfill disposal of certain categories of solid waste may result in gas generation, mainly methane, and a highly polluted leachate. The methane may be drawn off, to avoid a flammable hazard on- or off-site. The leachate is pumped off for treatment. 

NOTE - Petrochemical plants also generate significant amounts of solid wastes and sludges, some of which may be considered hazardous because of the presence of toxic organics and heavy metals. Spent caustic and other hazardous wastes may be generated in significant quantities examples are distillation residues associated with units handling acetaldehyde, acetonitrile, benzyl chloride, carbon tetrachloride, cumene, phthallic anhydride, nitrobenzene, methyl ethyl pyridine, toluene diisocyanate, trichloroethane, trichloroethylene, perchloro-ethylene, aniline, chlorobenzenes, dimethyl hydrazine, ethylene dibromide, toluenediamine, epichlorohydrin, ethyl chloride, ethylene dichloride, and vinyl chloride. 

Sources Assessment of Atmospheric Emissions from Petroleum Refining, Radian Corp., 1980 Petroleum Refining Hazardous Waste Generation, U.S. EPA, Office of Solid Waste, 1994. 

The Solid ira.ste Disposal Act was passed in 1965 to address Ute problem of wlitit to do with the increasing amounts of solid wastes being generated. It was designed to ... 

Coke byproduct wastes. Coke, used in the production of iron, is made by heating coal in high-temperature ovens. Throughout the production process many byproducts are created. The refinement of these coke byproducts generates several listed and characteristic wastestreams. However, to promote recycling of these wastes, U.S. EPA provided an exclusion from the definition of solid waste for certain coke byproduct wastes that are recycled into new products. 

Splash condenser dross residue. The treatment of steel production pollution control sludge generates a zinc-laden residue, called dross. This material, generated from a splash condenser in a high-temperature metal recovery process, is known as a splash condenser dross residue. Because this material contains 50 to 60% zinc, it is often reclaimed, reused, or processed as a valuable recyclable material. Facilities commonly handle this material as a valuable commodity by managing it in a way that is protective of human health and the environment, so U.S. EPA excluded this residue from the definition of solid waste. 

Mineral processing spent materials. Mineral processing generates spent materials that may exhibit hazardous waste characteristics. Common industry practice is to recycle these mineral processing wastes back into the processing operations to recover mineral value. U.S. EPA created a conditional exclusion from the definition of solid waste for these spent materials when recycled in the mineral processing industry, provided the materials are stored in certain types of units and are not accumulated speculatively. 

Degradation of solid waste materials in a landfill proceeds from aerobic to anaerobic decomposition very quickly, thereby generating gases that collect beneath the closure FML. Almost 98% of the gas produced is either carbon dioxide (CO2) or methane (CH4). Because C02 is heavier than air, it will move downward and be removed with the leachate. However, CH4, representing about 50% of the generated gas, is lighter than air and, therefore, will move upward and collect at the bottom of the facility s impermeable FML. If the gas is not removed, it will produce a buildup of pressure on the LML from beneath. 

---