and Integrated Pest Management - part - usaid

426 PSTICIDE' MANAGIFMIENT AND 1IM INSOUTHEAST ASIA
Table 1. Comparison of different regulations for combustions.
Standard
regulations
Mi
Tempemrature
Mi.
Air-supply
Mi
residence
time
EPA (United
States Environmental
Protecdon
A cncvofair
I 100 C
with air
supply
TA-Luft, 1983
West Germany
(Regulations
for the purity
1200 0 C
Commercial
Incinerator/
turbulence
reactor
1500 0 C -
1600 0 C
11% with air
supply
Rotary
kiln of
a cement
plant
1850 0 C
30%
1 sec. 0.3 sec. 0.3 sec +1 h
According to air purity regulations (TA-Luft of 1974 of West Germany and
the amendment of 1983), the requirements for the incineration of substances
which contain PCB (Polychlorinated Biphenyls) are the following: minimum
temperature 12001C at a residence time of 0.3 seconds, minimum air supply
11%. A comparison of the regulations and criteria for combustion of pesticides
is given in Table 1.
Polychlorinated Dibenzodioxins (PCDD) and related compounds are not
formed due to the high temperature of 1850 0 C in a rotary kiln. Dioxins and the
related compounds are split up into harmless fragments. The notorious 2,3,7,8-
TCDD (Tetrachlordibenzodioxin) and its 22 isomers are known as the "Sevesopoison"
(Appendix I). They and the related Polychlorinated Dibenzofurans
(PCDF) are highly poisonous substances These products are formed during a
radical reaction, when hydrocarbons are incompletely decomposed in the presence
of substances which contain chlorine at temperatures between 6001C and 800 0 C.
These are the conditions in normal refuse incinerators. Dioxins have been found
in the exhaust gas of such incinerators ( Appendix II).
The group of PCDD can be decomposed completely by high temperatures.
At temperatures over I100oC and a residence time of 0.1 second, an annihilation
of >99.9999% has been found (Kennedy et al. 1978).
Impurities such as chlorophenols are found in the herbicides 2,4,5-T; 2,4-Dester,
acid, amine, and in pentachlorophenole (PCP) and in many preparations
such as wood preservatives. Under unfavorable conditions dioxins can be formed
during combustion.
Other combustion studies included a US Air Force study (Hutzinger et al.
1982), in which a mixture of herbicides known as Agent-Orange was burnt with
a minimum access of 30% air, and at combustion-wall temperature of 1400 0 C.