Agriculture Reference
In-Depth Information
The advantages of thermal systems include (1) a potential for energy recov-
ery; (2) volume reduction of the contaminant; (3) detoxification as selected
molecules are reformulated; (4) basic scientific principles, engineering designs,
and technologies that are well understood from a wide range of other applica-
tions, including electric generation and municipal solid waste incineration; (5)
application to most organic contaminants, which comprise a large percentage
of the total contaminants generated worldwide; (6) the possibility to scale the
technologies to handle a single gallon per pound (liter per kilogram) of waste
or millions of gallon per pound (liter per kilogram) of waste: and (7) land areas
that are small compared to many other facilities (e.g., landfills). In all processes
involving thermal destruction, the ultimate products will include CO 2 , a known
greenhouse gas. Thus, even a successful design will contribute to global problems,
so the most preferable approach is to avoid the pollution in the first place.
Each system design must be customized to address the specific contaminants
under consideration, including the quantity of waste to be processed over the
planning period as well as the physical, chemical, and microbiological character-
istics of the waste over the planning period of the project. The space required
for the incinerator itself ranges from several square yards, to possibly the back
of a flatbed truck, to several acres used to sustain a regional incinerator system.
Laboratory testing and pilot studies matching a given waste to a given incinerator
must be conducted prior to the design, siting, and construction of each inciner-
ator. Generally, the same reaction applies to most thermal processes: gasification,
pyrolysis, hydrolysis, and combustion 14 :
C 20 H 32 O 10 + x 1 O 2 + x 2 H 2 O
y 1 C + y 2 CO 2 + y 3 CO + y 4 H 2
+ y 5 CH 4 + y 6 H 2 O + y 7 C n H m
The coefficients x and y balance the compounds on either side of the equa-
tion. The delta above the arrow indicates heating. In many thermal reactions,
C n H m includes the alkanes, C 2 H 2 ,C 2 H 4 ,C 2 H 6 ,C 3 H 8 ,C 4 H 10 ,andC 5 H 12 ,and
benzene, C 6 H 6 . Of all of the thermal processes, incineration is the most common
process for destroying organic contaminants in industrial wastes. Incineration is
simply the heating of wastes in the presence of oxygen to oxidize organic com-
pounds (both toxic and nontoxic). The principal incineration steps are shown in
Figure 3.6.
Applying Thermal Processes for Treatment
A word of warning when choosing incineration as the recommended technology:
The mere mention of “incineration” evokes controversy in communities, as there
Search WWH ::

Custom Search