Environmental Engineering Reference
In-Depth Information
11.4.6 Incineration
Incineration by rotary kiln has been used to treat hazardous materials including waste,
contaminated soils, and sediments. Other types of incineration include luidized bed, cir-
culating bed combustor, and infrared combustion. In the rotary kiln technique, heat is
supplied with a burner in a kiln, as shown in Figure 11.8, and the materials can be carbon-
ized when the contaminants are released by vaporization. Flue gas treatment is required
in this case. Temperatures for organic contaminants are in the range of 800°C to 1200°C
(USEPA, 1998). On-site mobile units or off-site treatment facilities are employed. In Japan,
this rotary kiln technique is also recommended as one of the treatment techniques for
sediments contaminated with dioxin. PCBs can also be treated. Costs can be high in the
range of $1000 to 1500/m
3
(FRTR, 2007).
There are soils contaminated with hydrocarbons in many industrial sites and oil rein-
eries. Thermal treatments are the most popular and versatile because they can be effec-
tively applied to a wide range of organic contaminants (Merino and Bucalá, 2007). At
different temperatures (150°C-800°C), results from Merino and Bucala (2007) showed that
at about 300°C the hexadecane can be removed almost completely from the soil matrix
(99.9% destruction removal eficiency, DRE) and that temperatures above this value do not
improve the removal eficiency noticeably. In Japan, treatment of excavated and dredged
materials is required for materials with dioxin levels higher than 3000 pg-TEQ/g. The rec-
ommended techniques are as follows:
• Melting (geo-melting technique) (>1200°C)
• Incineration (rotary kiln incinerator) (1100°C)
• Low-temperature thermal degradation (400°C-600°C)
• Chemical decomposition (350°C)
Dried excavated or
dredged materials
Gas
emissions
100°C
1100°C
Rotary kiln
Treated
materials
FIGURE 11.8
Rotary kiln treatment of contaminated soil or sediments.
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