Page 108 - Materials Chemistry, Second Edition

CAT3525_C04.qxd 1/27/2005 11:12 AM Page 79
Characterization of Solid Waste 79

TABLE 4.14
Cadmium (tons) in Products in MSW, 1970–2000

Products 1970 1986 2000 Percentage
Household
batteries 53 930 2,035 Increasing
Plastics 342 502 380 Variable; decreas-
ing after 1986
Consumer
electronics 571 161 67 Decreasing
Appliances 107 88 57 Decreasing
Pigments 79 70 93 Variable
Glass and
ceramics 32 29 37 Variable
All others 12 8 11 Variable
Total 1196 1788 2684
Source: U.S. EPA, 2000b. With permission.

TABLE 4.15
Discards of Mercury (tons) in Products in MSW, 1970 to 2000
a
Product 1970 1980 1989 2000
Household batteries 310.8 429.5 621.2 98.5
Electric lighting 19.1 24.3 26.7 40.9
Paint residues 30.2 26.7 18.2 0.5
Fever thermometers 12.2 25.7 16.3 16.8
Thermostats 5.3 7.0 11.2 10.3
Pigments 32.3 23.0 10.0 1.5
Dental uses 9.3 7.1 4.0 2.3
Special paper coating 0.1 1.2 1.0 0.0
Mercury light switches 0.4 0.4 0.4 1.9
Film pack batteries 2.1 2.6 0.0 0.0
Total Discards 421.8 547.5 709.0 172.7
a Discards before recovery.
Source: U.S. EPA, 1992. With permission.

waste stream (e.g., solvents, nickel–cadmium household batteries) will potentially improve
leachate properties and prevent groundwater contamination. Secondly, composition must be
known for evaluating alternative MSW processing and recovery options. For example, if the
organic fraction of MSW is to be composted or is to be used as feedstock for the production of
other biological conversion products, information on the major elements (e.g., ultimate analysis)
that comprise the waste is important. Information will be required on trace element composition
in the waste as well; for example, even modest concentrations of cadmium, arsenic, or lead may
be detrimental to efficient composting or biogas production. Finally, the feasibility of MSW com-
bustion is directly affected by chemical composition. Wastes can be considered a combination of
semi-moist combustible and noncombustible materials. If solid wastes are to be used as a fuel,
some important properties to determine include ultimate analysis, proximate analysis, energy
content, and particle size distribution.