and Integrated Pest Management - part - usaid

DE9IRUCtION OF PESTICIDE AND CIIEMICAL WASTES 42.5
TEST PROCEDURE
In the laboratory, chemical waste containing organic solvents and pesticides
is collected in special safety containers. Waste has to be in a liquid form for
combustion in the cement kiln. Solid waste is dissolved in kerosene while
concentrated liquid waste is diluted with kerosene. The mixture of waste and
kerosene is brought to the cement plant where ii is poured into the fuel storage
tank of the rotary kiln. The chemical waste is diluted with the oil in the storage
tank. From there it proceeds to the oil burner in the kiln where combustion
takes place. The advantages of dissolving/diluting the pesticide waste in the fuel
are that the concentrated pesticides are diluted considerably and the pesticide waste
is not incinerated all at once, but over a period of time.
RESULTS
According to the list of pesticides by Perkow (1983/85), which contains 486
active ingredients, 43 substances are not suitable for incineration by means of
rotary kiln, 18 substances are organic compounds, and 25 substances contain
metals. Chemical waste containing the following substances are not suitable for
combustion in the cement kiln:
* Heavy metals: Pb, Zn, Sn, Cr, Cu, Cd, Hg, TI
* Highly halogenated compounds
* Inorganic compounds
Examples:
Mercury compounds Phenyl mercury acetate, Phenyl mercury
chloride
Zinc compounds Propineb, Methylmetiram, Zineb, Ziram,
Mancozeb)
Tin compounds Azocyclotin, Cyhexatin, Fenbutatin oxide,
Fentin acetate, Fentin hydroxide
Compounds containing bromine Methyl bromide, Naled, Bromopropylate,
Dibromchlorpropanc, Ethylen dibromide
Inorganic compounds Potassium cyanide, Hydrocyanic acid,
Calcium cyanamide, Sodium-cyanide,
phosphine, Zinc phosphide, Thallous
sulfate.
Cement kilns can also be used for the destruction of pesticide waste and
chlorinated organic solvents. Chemical waste which needs after-treatment, and/or
which has to be stored in chemical waste depots are not suitable for incineration
in a rotary kiln. The same rule applies to compounds which can only be
incinerated when special safety precautions have been taken.
UTILITY OF TIlE ROTARY KILN
The conditions in the rotary kiln are similar to the conditions in a
turbulence reactor of an incinerator. The temperatures in such a reactor are
1500OC-1600 0 C and the residence time is 0.3 seconds.