Review: mercury in waste incineration

The paper investigates the sources of mercury (Hg) in municipal/industrial waste and the consequences of the presence of this pollutant for the incineration of this waste. About 1990 the average mercury concentration of the feed stream to incinerators was about 4 mg kg(-1). The concentration decreased considerably during the last decade thanks to a considerable reduction of the application of mercury and to the introduction of effective battery return systems. Presently the mercury concentration in municipal SOLID waste is approximately 2 mg kg(-1). During incineration mercury passes practically for 100% in the flue gas. The techniques for mercury removal from flue gases are discussed at the hand of practical examples. It is concluded that there are a number of processes which guarantee mercury concentrations of <50 microg Nm(-3) in the clean gas, the present emission limit concentration. All mercury control processes produce a new solid or liquid waste stream that contains the mercury removed from the flue gas. This stream has to be disposed of as hazardous waste in a qualified landfill. The flue gas from waste incinerators undergoes very rapid dispersion and dilution after leaving the incinerator stack. It follows that the maximum mercury concentration in the ambient air will remain at least five to six orders of magnitude below the lowest MAC value (=Maximum Admissible Concentration in work spaces) and that public health will not be threatened.