Metals incinerator residues

Misleading also is the idea that vinyl should be harmed from incinerators because it contains heavy-metal additives. This is an evolving issue. Most vinyl products do not contain heavy metals and vinyl is a small fraction in feed to incinerators. Reformulation to replace heavy metals is in progress but some use is likely to continue. Banning vinyl from incinerators does not eliminate this problem. Rather, regulations should specify that incinerator residues (ash) be disposed of appropriately. 

Disposal of solid wastes is a significant problem for the petrochemical industry. Waste solids include water treatment sludge, ashes, fly ash and incinerator residue, plastics, ferrous and nonferrous metals, catalysts, organic chemicals, inorganic chemicals, filter cakes, and viscous solids. 

Inorganic contaminants cannot be destroyed by incineration. Residual ash with elevated levels of heavy metals must be stabilized prior to disposal. 

A similar calculation for the riverine inputs (Ligure 3) yields the following results Pb = 14, Zn = 5, Cd = 40, Cr = 7.5, Cu = 6, Ni = 8. With the exception of Pb and Cd, the increases for Zn-Cr-Cu-Ni are similar. Smelting wastes and coal fly ash releases are the common sources of these four metals. Gasoline residues are an obvious source of the Pb increases and urban refuse incineration is a major source of the Cd increase (Nriagu and Pacyna, 1988). 

The finer soil fraction contains adsorbed organics, small metallic particles, and bound ionic metals. This fraction may be treated further to remove the contaminants, or it may be incinerated or landfilled. The "clean" coarse fraction may contain some residual metallic fragments. With metal contamination, both the fine and coarse soil fractions may be leached with an acid solution to remove the metals. 

Dissolution. Plutonium is solubilized in nitric acid solutions at Rocky Flats. The feed material consists of oxide, metal and glass, dissolution heels, incinerator ash and sand, slag, and crucible from reduction operations. The residues are contacted with 12M HNO3 containing CaF2 or HF to hasten dissolution. Following dissolution, aluminum nitrate is added to these solutions to complex the excess fluoride ion. 

Lab packs Laboratories commonly generate small volumes of many different listed hazardous wastes. Rather than manage all these wastes separately, labs often consolidate these small containers into lab packs. Trying to meet the individual treatment standards for every waste contained in a lab pack would be impractical. To ease the compliance burden, U.S. EPA established an ATS for lab packs that allows the whole lab pack to be incinerated, followed by treatment for any metal in the residues. Treatment using this alternative standard satisfies the LDR requirements for all individual wastes in the lab pack. 

There is some uncertainty about the potential presence of metal in the TCE-contaminated soil of Area 2. If metal concentrations of concern are present, only Alternatives 2 and 5 would protect against direct contact and further groundwater contamination through a cap and incineration, respectively. Incineration of metal-contaminated soil may result in a hazardous waste residue, which would have to be disposed of in a hazardous waste landfill. Alternatives 3 and 4 rely on vapor extraction and would not lower risks from metal to human health or the environment. 

Incineration reduces the volume of hazardous waste by converting solids and liquids to ash. Land disposal of ash, as opposed to untreated hazardous waste, is therefore both safer and more efficient. Incineration, however, will not destroy inorganic compounds, such as metals, present in hazardous waste. Residue ash from incinerators is subject to applicable RCRA standards and may need to be treated for metals or other nonorganic constituents prior to land disposal. 

Staging empty metal drums containing residual flammables too close to a waste disposal incinerator, fired process heater or other ignition source. 

The same modern incinerators equipped with scmbbers, bag-filters, electro-precipitators, secondary combustion chambers, stacks, etc., are equally efficient for disposal of hazardous PCBs, dioxin, USEPA priority pollutants, and so on, if they are properly designed, installed, and managed. Incineration technology is definitely feasible, and should not be overlooked. The only residues left in the incinerators are small amount of ashes containing metals. The metal-containing ashes may be solidified and then disposed of on a landfill site. 

Unfortunately, the secondary residues (BA, FA, FC) of conventional MSW incinerators usually contain high metal concentrations as a consequence, they cannot be re-used as secondary raw materials. Air pollution control (APC) residues, which represent a mixture of FA and FC, must be treated prior to landfilling in order to reduce the leachability of heavy metals (ABB-EAWAG-EMPA-KEZO 1990 EKESA 1992 BUWAL 1998). Ideally, heavy metal concentrations could be made sufficiently low, so that MSW residues could be used without problems. In many European countries, leachability is the criterion by which a material might be selected for re-use. 

Although the role of crystalline phases in the leachability of HT materials is unclear and must be examined from case to case, the identified silicates and oxides are overall more resistant to corrosion than silicate glass and residues of incineration (Scholze 1991). Thus, a clear assessment of the durability of HT materials as a function of crystalline components must take into account the combined effects of their enrichment or depletion in trace metals, their individual leachability, the increase (but sometimes decrease) in overall reactivity due to local heterogeneities and increased Sspec (Jacquet-Francillon et al. 1982 Bickford Jantzen 1984 Jantzen Plodinec 1984 Scholze 1991 Adams 1992 Sproull et al. 1994 Sterpenich 1998). 

Three detailed studies are reviewed here that examine the precise nature of the chemical stabilization of metals in MSW incineration bottom ash (Crannell et al. 2000), scrubber residue (Eighmy et al. 1997), and vitrification dust (Eighmy et al. 1999). 

Injurious Metals.—These may be derived either from the vessels in which the products are prepared or stored or from mineral colours added to some extent they may be detected in the ash. For a more complete investigation, especially of metals which may be eliminated during the incineration as volatile compounds, use is made of one of the known methods for the destruction of organic substances, e.g., treatment with hydrochloric acid and potassium chlorate, the residue being examined by the ordinary methods of qualitative analysis. 

Detection of Heavy Metals.—200 c.c. of the vinegar, made alkaline with sodium carbonate and containing a little nitre, are evaporated, the residue incinerated and the ash examined by the ordinary analytical methods. 

Metals, especially copper, zinc and lead, may be found in spirits in small quantities derived from the distillation apparatus or the storage vessels. They are detected and determined by evaporating a sufficient quantity of the liquid, incinerating the residue and treating the ash by the ordinary methods of qualitative and quantitative analysis. 

Ash.—The dry residue from the determination of the water is incinerated and the ash weighed. If this exceeds 1%, adulteration with mineral matter is probable, this being confirmed by qualitative analysis of the ash. Such analysis is useful in any case to detect the presence of heavy metals (especially iron), which may be introduced during the manufacturing processes and are harmful in the dyeing. The ash of alizarin consists normally of sodium or calcium salts. 

Soils may also become contaminated with industrial pollutants or with agricultural chemicals. For example, fields located close to industrial plants such as incinerators or metal smelters can gradually accumulate residues of combustion products and other chemicals from the fall-out from smoke plumes. Organo-chlorine pesticides, which are now largely banned, can persist in soils for many years and nitrates used in fertilisers can accumulate in soils which, under certain growth conditions, can result in high levels in certain crops. 

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