Metals waste sites

Electrokinetics. Electrokinetics is a tested technology that has been used for over half a century to dewater and stabilize soils, and has recently been investigated for in situ use at hazardous waste sites (23). Primarily used for metals removal, the technology utilizes an electrical field to generate a flow and concentration gradient in porous and semiporous soils. 

Groundwater is vulnerable to pollution by chemicals carried by rainwater, leaching from waste sites or from waste water carrying industrial or agricultural effluent. Treatment of drinking water may remove some, but not all, of these contaminants. Some polycarbonate or metal water pipes that are lined with epoxy resin lacquers may release bisphenol A. 

Lead has been identified in a variety of environmental media (air, surface water, groundwater, leachate, soil, sediment, fish and game animals) collected at 1,026 of the 1,467 current and former NPL hazardous waste sites (HazDat 1998). Lead is the most frequently found metal at hazardous waste sites (Reed et al. 1995). 

Besides the organic pollutants mentioned above, e-waste recycling activities are also releasing various heavy metals such as Hg, Cd, Cr, Cu, Ni, Pb, and Zn [14]. These e-waste-derived heavy metals pose extremely high risk to the environment and humans [67], especially at e-waste processing sites. Numerous previous studies suggested that most environmental matrices around e-waste sites, such as air, soil, sediment, and dust, have been severely contaminated by these heavy metals (Table 2) [71-75],... 

Surface dust from e-waste sites also contained enriched metals. Elevated mean concentrations of heavy metals, such as Pb (52,770 mg/kg), Cu (13,400 mg/kg), Zn (5,080 mg/kg), and Ni (605 mg/kg), were found in surface dust collected from e-waste recycling workshops in Guiyu (Table 2) [14]. The mean concentration of Pb (52,770 mg/kg) was 29 times higher than that in floor dust samples from printer circuit board component separation workshops in East Delhi, India. This may indicate that Pb pollution in e-waste sites of China was much more serious than... 

Combining data from stream sediment analyses with data on historic mining areas, the emission risks of old mine waste sites are evaluated systematically throughout Austria. Univariate and multivariate statistics serve to identify areas with naturally, or anthropogenically, elevated heavy metal concentrations (Fig. 4). Lead and zinc mineralization for... 

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. 

Brookhaven National Laboratory s (BNL s) biochemical recovery of radionuclides and heavy metals is a patented biochemical recovery process for the removal of metals and radionuclides from contaminated minerals, soil, and waste sites. In this process, citric acid, a naturally occurring organic complexing agent, is used to extract metals and radionuclides from solid wastes by the formation of water-soluble, metal-citrate complexes. The complex-rich extract is then subjected to microbiological biodegradation that removes most of the extracted heavy metals. 

The vendor claims that the CCBA process can be used on a variety of wastes, including sludges, sediments, and soils, contaminated with mixed organics and heavy-metal wastes. The process reduces the contaminated material to a nonleachable product composed of particles of sand to aggregate sizes. The treated wastes pass required leachability tests, and organic compounds are destroyed. The treated material can be disposed of on-site. 

In 1987, hazardous heavy metal wastes were produced in California at an annual rate of 140,000 ton/yr.1 Through April, 1989 the U.S. Environmental Protection Agency (EPA) had identified over 900 acutely dangerous hazardous waste disposal sites that required immediate cleanup through the Superfund program, and another 27,000 sites that may potentially qualify.2 Ultimately, the U.S. General Accounting Office believes that up to 425,000 waste sites will require cleanup in the next 50... 

Ceramic Bonding has embarked on a program to develop versatile equipment to aid metal fabricators in their efforts to eliminate hazardous waste generation. Because of the applicability of the CBI process to a variety of hazardous, heavy metal wastes, the CBI equipment is also a natural solution for site cleanup and municipal hazardous waste conversion. With this innovative technology, continued release of fugitive heavy metals into the environment can be halted. 

Silver is one of the basic elements that make up our planet. Silver is rare, but occurs naturally in the environment as a soft, "silver" colored metal. Because silver is an element, there are no man-made sources of silver. People make jewelry, silverware, electronic equipment, and dental fillings with silver in its metallic form. It also occurs in powdery white (silver nitrate and silver chloride) or dark-gray to black compounds (silver sulfide and silver oxide). Silver could be found at hazardous waste sites in the form of these compounds mixed with soil and/or water. Therefore, these silver compounds will be the main topic of this profile. Throughout the profile the various silver compounds will at times be referred to simply as silver. 

Exposure Levels in Humans. Silver has been detected in the blood, tissues, urine, and feces of humans. The only biological monitoring studies located consisted of small numbers of worker populations in chemical manufacturing industries. Studies that better characterize important sources of general population exposure and define populations with potentially high exposure, such as those located near hazardous waste sites, would be helpful. More specific information concerning the chemical from of silver present at hazardous waste sites would also be useful. These data would assist in developing a more accurate estimate of the potential for silver exposure from hazardous waste sites contaminated with the metal. 

Bitton, G., Campbell, M. and Koopman, B. (1992a) MetPAD A bioassay kit for the specific determination of heavy metal toxicity in sediments from hazardous waste sites, Environmental... 

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