Metal emissions, heavy, from incineration

Particulate Matter and Heavy Metal Emissions from Incinerators... 

The presence of heavy metals in the atmospheric particulate matter in Antarctica can be attributed to different sources, both natural and anthropogenic. Some authors state that almost all natural sources of heavy metals in Antarctica are generally situated in the southern hemisphere (4, 14, 15). The natural sources are normally volcanic activities, erosive processes, continental dusts, marine spray from the ocean, low-temperature biological processes, etc. (7, 10, 16-18). Important local human sources of heavy metal emissions into the Antarctic atmosphere are presumed to be the Antarctic stations and their activities, especially all kinds of transport, power plants, waste burning (incinerators), etc. (10, 12, 15, 19). 

In the scenario for the controlled landfill site the treatment of effluent from the site by sewage treatment and the incineration of the sludge are taken into account. An additional scenario is made for an uncontrolled landfill site, assuming DEHP emissions. However, in an uncontrolled landfill site not only DEHP will emit from the site but also other toxic releases like heavy metals. So the results presented for the uncontrolled landfill site are an underestimation. For a more realistic assessment of impacts related to the uncontrolled landfill of PVC, additional estimates are necessary for the emissions of (toxic) releases. As a consequence, the impact assessment score for human and aquatic ecotoxicity for the uncontrolled landfill site will increase. The relative contribution of DEHP to these scores will decrease because also other emissions which are in the present assumptions are now lacking, like heavy metals, will contribute to the score. 

Mercury is one of a number of toxic heavy metals that occur in trace amounts in fossil fuels, particularly coal, and are also present in waste materials. During the combustion of fuels or wastes in power plants and utility boilers, these metals can be released to the atmosphere unless remedial action is taken. Emissions from municipal waste incinerators can substantially add to the environmental audit of heavy metals, since domestic and industrial waste often contains many sources of heavy metals. Mercury vapor is particularly difficult to capture from combustion gas streams due to its volatility. Some processes under study for the removal of mercury from flue gas streams are based upon the injection of finely ground activated carbon. The efficiency of mercury sorption depends upon the mercury speciation and the gas temperature. The capture of elemental mercury can be enhanced by impregnating the activated carbon with sulfur, with the formation of less volatile mercuric sulfide [37] this technique has been applied to the removal of mercury from natural gas streams. One of the principal difficulties in removing Hg from flue gas streams is that the extent of adsorption is very low at the temperatures typically encountered, and it is often impractical to consider cooling these large volumes of gas. 

Normally, incinerator exhausts are monitored for temperature, CO, NO and O2. Data covering the entire spectrum of emissions are often collected only for short periods of time. More emission information is needed, especially for dioxins and furans, heavy metals, and PM. Limited research is underway for the development of reliable and rugged technologies that will provide the real time, continuous monitoring of the entire spectrum of emissions from incinera-tors. However, their routine use in incinerators as continuous emissions monitors is not practised yet. 

PVC has been under attack from environmental groups on a variety of grounds for a number of years. Because PVC contains chlorine, it may lead to the formation of chlorinated dioxins if it is disposed by incineration. While evidence suggests that the presence or absence of PVC is not very significant in dioxin emissions from well-controlled incineration, less important than combustion conditions, there is reason for concern about its presence in poorly controlled incineration systems. PVC has also been attacked because of concerns related to the carcinogenicity of its vinyl chloride monomer. Increasingly, lead and cadmium stabilizers used in some PVC resins are being restricted or banned, due to concerns about toxic effects of these heavy metals. 

The US rules from their EPA identify medical waste incineration as the third largest known source to the enviromnent of highly toxic dioxin, a known carcinogen thathas been linked to immune system disorders. Incineration is also responsible for about 10 percent of mercury emissions to the environment. Other pollutants from incineration include furans, acid gases, heavy metals and particulates. Given that alternatives to incineration are available, a complete phase-out of medical waste incineration is appropriate. ... 

Incineration of plastic waste either alone or as part of municipal waste is often pereeived by the public to be an environmentally unsound process because of the production of residual ash containing heavy metals and the possibility of dioxin formation from chlorine-containing waste. Like DDT, dioxins are persistent and accumulate in fatty tissue, but unlike DDT some of the many dioxins that could be produced by incineration are highly toxic to humans. Although experts agree that waste can be incinerated safely, at high temperature, without any dioxin emission, it is the potential risk that is the cause for concern to the general public. 

---