Mercury-containing waste solids

Nuclear Fuel Services, Inc. (NFS), developed the commercially available DeHg process for the low-temperature treatment of mercury-contaminated hazardous and mixed wastes. The technology uses a proprietary amalgamation process to convert mercury into a nonhazardous solid. The technology is now offered by Advanced Recovery Systems, Inc. The developer claims the technology can be used on sludges, hazardous and mixed wastes, and mercury-contaminated wastes containing tritium. 

In 1984 the Hazardous and Solid Waste Amendments to the Resource and Conservation Act of 1976 (RCRA) were passed prohibiting the land disposal of certain hazardous wastes. Among these amendments is the "California List" distinguishing hazardous wastes now banned from landfilling such as liquid wastes containing greater than 20 mg/1 mercury. This waste is subject to the treatment requirements for heavy metals which are metal recovery or solidification (40 CFR 268.7 (a) and 268.7 (b)). ... 

Primary copper processing results in air emissions, process wastes, and other solid-phase wastes. Particulate matter and sulfur dioxide are the principal air contaminants emitted by primary copper smelters. Copper and iron oxides are the primary constituents of the particulate matter, but other oxides, such as arsenic, antimony, cadmium, lead, mercury, and zinc, may also be present, with metallic sulfates and sulfuric acid mist. Single-stage electrostatic precipitators are widely used in the primary copper industry to control these particulate emissions. Sulfur oxides contained in the off-gases are collected, filtered, and made into sulfuric acid. 

Shredded circuit boards. Circuit boards are metal boards that hold computer chips, thermostats, batteries, and other electronic components. Circuit boards can be found in computers, televisions, radios, and other electronic equipment. When this equipment is thrown away, these boards can be removed and recycled. Whole circuit boards meet the definition of scrap metal, and are therefore exempt from hazardous waste regulation when recycled. On the other hand, some recycling processes involve shredding the board. Such shredded boards do not meet the exclusion for recycled scrap metal. In order to facilitate the recycling of such materials, U.S. EPA excluded recycled shredded circuit boards from the definition of solid waste, provided that they are stored in containers sufficient to prevent release to the environment, and are free of potentially dangerous components, such as mercury switches, mercury relays, nickel-cadmium batteries, and lithium batteries. 

Inorganic solid wastes, particularly those containing toxic metals and toxic metal compounds, used Raney nickel, manganese dioxide, etc. should be placed in glass bottles or lined fiber drums, sealed, properly labeled, and arrangements made for disposal in a secure landfill. Used mercury is particularly pernicious and small amounts should first be amalgamated with zinc or combined with excess sulfur to solidify the material. 

Sulfur- and nitrogen-containing compounds will produce their corresponding oxides and should not be incinerated without considering their effects on air quality. Halogenated hydrocarbons not only may affect air quality but also may corrode the incinerator. Also, organo-metallic compounds containing cadmium, mercury, and so on, are not recommended for incineration because of the potential for air and solid waste contamination. 

Toxic wastes, collected from different multimedia environments, can harm living systems. The contaminants in these wastes can be organic or inorganic [1, 2]. Organic contaminants (like PCB, Dioxin, see the chapter on Forensic Investigation of Leachates from Recycled Solid Wastes ) actually consist of harmless atoms arranged into noxious molecules. The inorganic contaminants contain toxic elements, such as lead, mercury, arsenic, and cadmium [ 16,17,41 ]. 

Approximately 80% of the mercury released from human activities is elemental mercury released to the air, primarily from fossil fuel combustion, mining, and smelting, and from solid waste incineration. About 15% of the total is released to the soil from fertilizers, fungicides, and municipal solid waste (for example, from waste that contains discarded batteries, electrical switches, or thermometers). An additional 5% is released from industrial wastewater to water in the environment. 

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