Surface treatments waste disposal

The dry powder process has several additional advantages over the wet process. For example, much less waste of enamel occurs because the dry over-spray is airborne and recycled in a closed system. No-pidde ground coats have broadened the apphcation of both wet-process and dry-process systems. These enamels are appHed over cleaned-only metal. Thus the problems of disposing of pickling acid wastes containing iron sulfates and nickel wastes are eliminated (see Metal surface treatments) (7). 

One technique used in a number of facilities that utilize molten salt for metal surface treatment prior to pickling is to take advantage of the alkaline values generated in the molten salt bath in treating other wastes generated in the plant. When the bath is determined to be spent, it is in many instances manifested, hauled off-site, and land disposed. One technique is to take the solidified spent molten salt (molten salt is sold at ambient temperatures) and circulate acidic wastes generated in the facility over the material prior to entry into the waste treatment system. This in effect neutralizes the acid wastes and eliminates the requirements of manifesting and land disposal. 

This series of prohibitions restricts how wastes subject to LDR requirements are handled. The most visible aspect of the LDR program is the disposal prohibition, which includes treatment standards, variances, alternative treatment standards (ATSs), and notification requirements. Land disposal means placement in or on the land, except in a corrective action unit, and includes, but is not limited to, placement in a landfill, surface impoundment, waste pile, injection well, land treatment facility, salt dome formation, salt bed formation, underground mine or cave, or placement in a concrete vault, or bunker intended for disposal purposes. The other two components work in tandem with the disposal prohibition to guide the regulated community in proper hazardous waste management. The dilution prohibition ensures that wastes are properly treated, and the storage prohibition ensures that waste will not be stored indefinitely to avoid treatment. 

Figure 20.2 shows the surface equipment used in a typical subsurface waste-disposal system. Detailed discussion of surface treatment methods can be found in Warner and Lehr.6 The individual elements are listed in the following ... 

Uchida, T., Itoh, I. Harada, K. 1996. Immobilization of heavy metals contained in incinerator fly ash by application of soluble phosphate - treatment and disposal cost reduction by combined use of high specific surface area lime . Waste Management, 16, 475-481. 

Currently, there is much variability in the United States in establishing treatment standards for PAHs in soil and groundwater. For example, Land Disposal Restrictions (LDR) govern the placement of materials destined for any land disposal including landfill, surface impoundments, waste pits, injection wells, land treatment facilities, salt domes, underground mines or caves, and vaults or bunkers. Accordingly, treatment standards for all listed and characteristic hazardous wastes destined for land disposal have been defined (U.S. EPA, 1991) These values thus represent one potential set of treatment standards for PAHs. However, for PAHs,... 

A number of dispositions could be acceptable for high-hazard chemical waste, including destruction (e.g., incineration), treatment to reduce the hazard to levels that would be acceptable for near-surface disposal, or disposal using a technology considerably more isolating than a near-surface facility. At the present time, there are no planned alternatives to near-surface facilities for disposal of high-hazard chemical wastes in the United States.16 However, there do not appear... 

In view of the necessity for getting waste disposal under control coupled with the limited fossil raw material resources, biodegradable polymer and in particular polymers from renewable resources will gain importance in the future. In the most sensitive application area, food contact materials and articles, it is possible initially to use these materials in very limited amounts. The easy decomposition of these packaging materials is in opposition with the inertness needed to protect packaged food. These polymers are particularly sensitive to moisture. By finishing operations such as surface treatments, one could improve the inertness of these polymers. However, the degradability would be diminished by such processes. 

Etching solutions can be purchased from a number of sources. They include Fluoro Etch by Acton Corp. and Tetra-Etch by W. L. Gore Associates. Some companies, such as Acton Corp., provide surface treatment service. Operational safety and waste disposal are two issues concerning parties that deal with etching solutions. 

Acid-containing wastes are produced in many industries. Thus, in leaching of minerals, in regeneration of cation exchangers, and in metal surface treatment, only a part of the acid is utilized (due to the reduced activity at the lower acid concentration). The acids plus salts comprising aqueous solutions formed in these operations as well as in others (e.g., zinc electrowinning) are neutralized in most cases and disposed of. Efficient separation and recovery of the acid values is more beneficial, as it would save on acid and base consumption, reduce discharge of solution or solids, and enable recovery of other valuable components (e.g., metal values) from the deacidified solutions. 

During the 1970s and the early 1980s, toxic chemicals and other hazardous wastes were treated by land disposal or by incineration. The Hazardous and Solid Waste Amendments (HSWA) of 1984 to the Resource Conservation and Recovery Act (RCRA) severely restricted disposal of wastes in untreated landfills, surface impoundments, and land treatment units. Additionally, negative public opinion was focused on the disproportionate risk borne by those living near incinerators and other hazardous waste treatment and disposal facilities. Environmental laws passed in the 1970s clearly articulated public and congressional dissatisfaction with early site remedies that wholly consisted of containment, off-site disposal, and incineration. 

Laser marking is an ink-free process which produces a permanent rub-fast, solvent resistant, scratch proof mark with no waste, and is free of flammable or volatile solvents and then-subsequent disposal. These permanent markings cannot be removed without damaging the product, which is ideal for safety concerns. The laser marking process does not require any form of surface treatment, in fact, a film of water on the product will have no effect on the marking process. Since the mark is etched into the plastic product, there is no problem of adhesion, even on polyethylene and polypropylene. 

Several waste disposal options used to date include direct landfilling, storage in surface impoundments, physical/chemical/biological treatment, chemical stabilization, and thermal destruction. The landfilling, storage, and mass-bum incineration are the options of the past, so that we can only expect to see an increase... 

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