Metal Waste Generation

The first step in this process is undertaken in Section 4.0, in which the industries mentioned in Table 2-1 are examined, and the activities that produce wastes are identified. 

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As a result, there is heightened interest in preventing metal waste generation, in recycling the wastes once they are produced, and in developing treatment alternatives that reduce the amount of waste requiring disposal. 

Applications of this recovery and treatment method may provide alternative disposal options for other heavy metal wastes generated in the medical research industry. 

Table VIII. Heavy Metal Waste Generated for AA-Sized NiCd Batteries...

Each vehicle generates 500—800 pounds of residue. The aimual U.S. total is about 3.5 million tons or about 1.3% of the municipal soHd waste generated aimuaHy (3). The mixture is too complex to separate and recycle. Depending on the amount of glass, water, metal, and dirt present, the residue... 

The degree of availability of recyclable resources such as scrap and wastes is a widely varying parameter. By way of illustration, scrap can be classified as new scrap (or in-process scrap) and old scrap (or post-consumer scrap). The former, which constitutes the majority of scrap processed at present, is derived mainly from the wastes generated during metal production and fabrication, and can be reclaimed and recycled with relative ease. 

All metal finishing facilities have one thing in common—the generation of metal-containing hazardous waste from the production processes. Reducing the volume of waste generated can save money and at the same time decreases future liabilities. Typical wastes generated are as follows ... 

This section identifies areas for reducing waste generation. It also suggests techniques available to metal finishers for waste reduction and is intended to help metal finishing shop owners decide whether waste reduction is a possibility. 

CDHS, Hazardous Waste Generated by Metal Refinishing Facilities, Fact Sheet, California Department of Health Services, Toxic Substances Control Program, Alternative Technology Division, April 1990. 

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. 

Scrap metal comprises worn or extra bits and pieces of metal parts, such as scrap piping and wire, or worn metal items, such as scrap automobile parts and radiators. If scrap metal is reclaimed, it is a solid waste and is subject to hazardous waste regulation. Scrap metal is also regulated as a solid waste when used in a manner constituting disposal burned for energy recovery, used to produce a fuel, or contained in fuels or accumulated speculatively. This does not apply to processed scrap metal, which is excluded from hazardous waste generation entirely. 

Symmetrical and unsymmetrical benzoins have been rapidly oxidized to benzils in high yields using solid reagent systems, copper(II) sulfate-alumina [105] or Oxone-wet alumina [105, 106] under the influence of microwaves (Scheme 6.32). Conventionally, the oxidative transformation of a-hydroxy ketones to 1,2-diketones is accomplished by reagents such as nitric acid, Fehling s solution, thallium(III) nitrate (TTN), ytterbium(III) nitrate, ammonium chlorochromate-alumina and dayfen. In addition to the extended reaction time, most of these processes suffer from drawbacks such as the use of corrosive acids and toxic metals that generate undesirable waste products. 

A prototype system (100 kg waste per hour) which utilizes a nonrefractory metal vessel is under construction and was scheduled to begin operating in late 1983 (10). The unit is designed for transport to field sites for temporary waste destruction such as in cleanup of a hazardous waste site or continuous waste destruction at a waste generator s plant site. 

Trends in solid waste generation have changed in some important ways over the past four decades. As the table on pages 136-137 shows, the contribution to the total solid waste volume for most constituents stayed about the same between 1960 and 2000 (the last year for which data are available). The two exceptions are metals, whose share of the MSW had dropped from about 12 percent in 1960 to less than 6 percent in 2000, and plastics, which made up only 0.4 percent of all MSW in 1960 and now constitute nearly 11 percent of all such wastes. 

Fly ash Fly ash is an industrial solid waste generated in thermal power plants. Fly ash can be easily solidified after the heavy metals have been adsorbed. 

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