Forming hazardous wastes

Adhesion requires the use of a variety of compounds that may be safe, hazardous, flammable, or form hazardous waste. Table 13.5 provides a partial list of some of the more commonly used chemicals. There has been extensive collaboration between the industry and the governmental environmental protection agencies to reduce all emissions. For instance, the Design for Environment (DfE) program in the Environmental Protection Agency s (EPA) Office of Pollution Prevention and Toxics has been a voluntary partnership with the industry to develop and distribute pollution prevention and environmental and human health risks on alternative chemicals, processes, and products. The DfE approach uses cleaner technologies... 

Transportation and Disposal. Only highly alkaline forms of soluble sihcates are regulated by the U.S. Department of Transportation (DOT) as hazardous materials for transportation. When discarded, these ate classified as hazardous waste under the Resource Conservation and Recovery Act (RCRA). Typical members of this class are sodium sihcate solutions having sihca-to-alkah ratios of less than 1.6 and sodium sihcate powders with ratios of less than 1.0. In the recommended treatment and disposal method, the soluble sihcates are neutralized with aqueous acid (6 Af or equivalent), and the resulting sihca gel is disposed of according to local, state, and federal regulations. The neutral hquid, a salt solution, can be flushed iato sewer systems (86). 

Dissolved Air Flotation. Dissolved air flotation (DAF) is used to separate suspended soflds and oil and grease from aqueous streams and to concentrate or thicken sludges. Air bubbles carry or float these materials to the surface where they can be removed. The air bubbles are formed by pressurizing either the influent wastewater or a portion of the effluent in the presence of air. When the pressurized stream enters the flotation tank which is at atmospheric pressure, the dissolved air comes out of solution as tiny, microscopic bubbles. Dissolved air flotation is used in many wastewater treatment systems, but in the United States it is perhaps best known with respect to hazardous waste because it is associated with the Hsted waste, K048, DAF flotation soflds from petroleum refining wastewaters. Of course, the process itself is not what is hazardous, but the materials it helps to remove from refining wastewaters. 

The only components in a coating powder which might cause the waste to be classified as hazardous are certain heavy-metal pigments sometimes used as colorants. Lead- (qv) and cadmium-based pigments (qv) are seldom used, however, and other potentially hazardous elements such as barium, nickel, and chromium are usually in the form of highly insoluble materials that seldom cause of the spent powder to be characterized as a hazardous waste (86). 

Toxic or hazardous wastes can be disposed of in fluidized beds by either chemical capture or complete destruction. In the former case, bed material, such as limestone, will reacl with hahdes, sulfides, metals, etc., to form stable compounds which can be landfilled. Contact times of up to 5 or 10 s at 1200 K (900°C) to 1300 K (1000°C) assure complete destruction of most compounds. 

Hazardous Wastes When hazardous wastes are generated, special containers are usually provided, and trained personnel (OSHA 1910.120 required such workers to have HAZWOPER training) are responsible (or should be) for the handling of these wastes. Hazardous wastes include solids, sludges, and hquids hence, container requirements vary with the form of waste. 

For PM applications, wet scrubbers generate waste in the form of a slurry or wet sludge. This creates the need for both wastewater treatment and solid waste disposal. Initially, the slurry is treated to separate the solid waste from the water. The treated water can then be reused or discharged. Once the water is removed, the remaining waste will be in the form of a solid or sludge. If the solid waste is inert and nontoxic, it can generally be landfilled. Hazardous wastes will have more stringent procedures for disposal. In some cases, the solid waste may have value and can be sold or recycled. 

Enter one of the following codes to identify the type of treatment or disposal method used by the off-site location for the chemical being reported. You should use more than one line for a single location when the toxic chemical is subject to different disposal methods the same location code may be used more than once. You may have this information in your copy of EPA Form SO, Item S of the Annual/Biennial Hazardous Waste Treatment, Storage, and Disposal Report (RCRA). Applicable codes for Part III, Section 6(c) are as follows ... 

Applicability Most hazardous waste slurried in water can be mixed directly with cement, and the suspended solids will be incorporated into the rigid matrices of the hardened concrete. This process is especially effective for waste with high levels of toxic metals since at the pH of the cement mixture, most multivalent cations are converted into insoluble hydroxides or carbonates. Metal ions also may be incorporated into the crystalline structure of the cement minerals that form. Materials in the waste (such as sulfides, asbestos, latex and solid plastic wastes) may actually increase the strength and stability of the waste concrete. It is also effective for high-volume, low-toxic, radioactive wastes. 

Maintains information about hazardous waste generators, transporters, disposal facilities, materials shipped, and how they have been shipped. Assists with Uniform Hazardous Waste Manifest document required by RCRA. Generates records and letters. Requires 200K memory plus IK memory for each record and a printer that can penetrate a six-part form. 

Handling hazardous ehemieals has beeome part of most people s everyday living. Just eonsider gasoline, and how most people fill their own tanks. In the manufaeturing arena, ehemieals are eommonplaee. On hazardous waste sites there are a variety of unknown ehemieal substanees and other hazards that may take the form of a solid, liquid, or gas. The eflfeets of exposure to toxie ehemieals may either be immediate (e.g., aeid burns) or delayed (e.g., lung damage from inhaling asbestos). There are four routes of ehemieal exposure that exist ... 

The audit/inspeetion form that you should use ean be developed from the safety plan. A qualified person should examine the safety plan and eome up with a eheeklist that should serve as an audit/inspeetion form. Allowanees should be made to inelude items not speeifieally noted in the safety plan but that may be observed during field walk-throughs. Certain highly pertinent seetions of what OSHA uses when performing a eomplianee inspeetion of hazardous waste sites is ineluded in Appendix D. This inspeetion/audit form eovers many of the basies and ean be used a general guide. 

The effectiveness of incineration has most commonly been estimated from the heating value of the fuel, a parameter that has little to do with the rate or mechanism of destraction. Alternative ways to assess the effectiveness of incineration destraction of various constituents of a hazardous waste stream have been proposed, such as assessment methods based on the kinetics of thermal decomposition of the constituents or on the susceptibility of individual constituents to free-radical attack. Laboratory studies of waste incineration have demonstrated that no single ranking procedure is appropriate for all incinerator conditions. For example, acceptably low levels of some test compounds, such as methylene chloride, have proved difficult to achieve because these compounds are formed in the flame from other chemical species. 

A large fraction of the hazardous waste generated in industry is in the form of dilute aqueous solutions. The special challenges of separation in highly dilute solutions may be met by the development of new, possibly liquid-filled, membranes by processes involving selective concentration of toxic chemicals on the surfaces of particles or by the use of reversed micelles. 

In establishing treatment standards, U.S. EPA applied the BDAT methodology to the typical forms of waste generated by industry. Some forms of hazardous waste are unique and were not taken into account by the BDAT process when treatment standards were established. As a result, U.S. EPA created a number of broad ATSs for special types of waste.2... 

U.S. EPA defines boilers as enclosed devices that use controlled flame combustion to recover and export energy in the form of steam, heated fluid, or heated gases. A boiler comprises two main parts, the combustion chamber used to heat the hazardous waste and the tubes or pipes that hold the... 

Hydrogen chloride and chlorine gases form when chlorinated organic compounds in hazardous wastes are burned. If uncontrolled, this chlorine can become a human health risk and is a large component in the formation of acid rain. U.S. EPA has developed different requirements to control the emissions of chlorine from the different classes of combustion units. 

Used oil distillation bottoms. When used oil is recycled, residues (called distillation bottoms) form at the bottom of the recycling unit. To promote the recycling of used oil and the beneficial reuse of waste materials, U.S. EPA excluded these residues from the definition of hazardous waste when the bottoms are used as ingredients in asphalt paving and roofing materials. 

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