Pesticide destruction

In 1974, federally recommended procedures were published under authority of the 1972 amendments of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) that addressed pesticide disposal (2). These recommendations identified an incinerator operating at 1000°C (1832°F) with 2-s retention time in the combustion zone as acceptable for destruction of organic pesticides. Other incinerators, such as those for municipal solid waste capable of effecting complete pesticide destruction, are also acceptable. During this same time frame, i.e., from the early 1970s to date, a number of research and demonstration studies have been conducted involving pesticide incineration. Most of these concern either the identification of incinerator... 

In a similar study, Versar, Inc., in 1974-1975, demonstrated for EPA that DDT and 2,4,5-T formulations were destroyed in a municipal sewage sludge incinerator in Palo Alto, California (5). The pesticides were added to sludge (which contained 20% by weight of solids) to form a mixture that was 2 to 5% by weight in pesticides. Destruction efficiencies ranged from 99.95 to 99.99% for an average hearth temperature from 600 to 690°C and an afterburner temperature from 650 to 660°C. 

Since 1974, the USEPA has conducted many incineration tests for pesticide destruction. Most pesticides tested were capable of being destroyed to an efficiency of more than 99.99%. The only exception was Mirex, with 98-99% destruction. However, investigators felt that destruction could be improved to the 99.99% level with a somewhat more effective incinerator design. Incineration has become very controversial in recent years because of the potential to generate dioxin under high temperature conditions. 

Despite the use of 2.5 million tons of pesticide worldwide, approximately 35% of potential crop production is lost to pests. An additional 20% is lost to pests that attack the food post-harvest. Thus, nearly one-half of all potential world food supply is lost to pests despite human efforts to prevent this loss. Pesticides, in addition to saving about 10% of world food supply, cause serious environmental and public health problems. These problems include human pesticide poisonings fish and bird kills destruction of beneficial natural enemies pesticide resistance contamination of food and water with pesticide residues and inadvertent destruction of some crops. 

Some pesticides, especially when applied by aircraft, drift into adjacent agricultural lands where they may damage crops. This type of destruction is estimated to cost at least 900 million... 

The literature has numerous citations on both the prevention and destruction of nitrosamines. Techniques, such as the use of scavengers or selective reactions, may be applied to commercial pesticide products. 

Effectiveness of prevention vs destruction Effect on the pesticide product Introduction of other chemical l -products... 

Brief notes are added on phosphorofluoridates even though their destruction by microbial activity— though clearly possible—is limited by their toxicity to the requisite microorganisms. One of the motivations for their inclusion is the fact that the hydrolytic enzyme(s) responsible for defluorination—organophosphorus acid anhydrase (OPA)—is widespread, and is found in a number of bacteria (Landis and DeFrank 1990). The microbial hydrolysis of organophosphorus pesticides and cholinesterase inhibitors is accomplished by several distinct enzymes, which are collectively termed organophosphorus acid anhydrases (OPAs). These have been reviewed (DeFrank 1991), so that only a few additional comments are necessary. 

The growing concerns about the public health and environmental impacts of pesticides have led many in the general public and the government to question whether all the benefits of pesticides, such as the perfect red apple, are worth the associated costs of environmental pollution, human illness and loss of life, bird kills, and the destruction of other beneficial natural organisms. Indeed, some agriculturists have been viewed as primarily concerned with promoting commercial interests rather than protecting public health and the environment. 

The usual method for disposing of pesticides in the USSR was walling them into spent quarries and mine shafts. For example, more than 3000 tons of pesticides were walled into unfitted vertical boreholes in the Krasnodar Krai. The complete destruction of pesticides has become a large environmental problem, comparable in scale to the problem of destroying chemical weapons stocks. About 40,000 tons of unused pesticides (banned or too old to be used) had accumulated in the countries of the former Soviet Union, about half of which are located in Russia. 

The district will benefit the most from a method for destruction of this toxic material called "Mobile plasma complex for recycling of unfit and unidentified pesticides", which has been designed by the "Colorit" Institute of Dnepropetrovsk. However the mentioned method still has to be ecologically and sanitary-epidemiologically evaluated by experts. 

Analysis and Fate of Surfactants in the Aquatic Environment Sample Preparation for Trace Element Analysis Non-destructive Microanalysis of Cultural Heritage Materials Chromatographic-mass spectrometric food analysis for trace determination of pesticide residues... 

This selective toxicity of the larvae s weapon suggests practical applications. Western subterranean termites are economically significant pests, considered to be the most destructive of all California termites. A pesticide directed specifically against them and harmless to other creatures would be environmentally friendly and extremely useful. Exterminators could rid a house of termites without endangering the residents or destroying beneficial insects. The chemical nature of this toxin is still unknown. We can only wonder what substance can rapidly paralyze one kind of termite and leave other insects unscathed. 

While much of this work has addressed the destruction of pesticides as such, most current activity is concerned with the more general problem of hazardous waste incineration. The following discussion summarizes some of the key studies that have dealt specifically with the incineration of pesticides and pesticide wastes, as well as hazardous waste incineration in general. 

A two-step laboratory thermal-decomposition analytical system involving vaporization and thermal destruction was developed in 1975 by the University of Dayton Research Institute for EPA (6). Vaporization of pure pesticide occurred at 200 to 300°C and was followed by decomposition in a quartz tube at temperatures exceeding 900 C. The destruction efficiencies for DDT, Kepone, and mirex exceeded 99.99% at 2-s residence time and greater than 900 C. 

In 1974 Midwest Research Institute operated a pilot-scale multiple chamber incinerator to evaluate for EPA the operational variables for pesticide incineration (8). The system included a. pilot-scale incinerator, a three-stage scrubber system, and a scrubber water treatment system. Nine pesticides (aldrin, atrazine, captan, DDT, malathion, mirex, picloram, toxaphene, and zineb) in 15 liquid and solid formulations were studied. Destruction efficiencies generally exceeded 99.99% over a range of temperatures and retention times ( 950 to 1100°C, 1.2 to 6 s, and 80 to 160% excess air). This study also documented the generation of measurable quantities of cyanide in the incinerator off-gas during the incineration of organonitrogen pesticides. 

TRW Systems, Inc., conducted a laboratory-scale incineration study for the U.S. Army from 1973 to 1975 (9). Eleven individual pesticide formulations and three mixed pesticide formulations containing six different active ingredients (chlordane, 2,4-D, DDT, dieldrin, lindane, and 2,4,5-T) were incinerated in a liquid injection incinerator. The experimental apparatus consisted of a fuel atomizer, combustion chamber, afterburner, quench chamber, and scrubber unit. Destruction efficiencies exceeded 99.99% for a minimum 0.4-s residence time at temperatures above 1000°C with 45 to 60% excess air. 

Molten salt is a technique that has been considered for the destruction of pesticides and other hazardous wastes for several years. In a recent study by Rockwell International for EPA (1 ), the destruction of solid hexachlorobenzene (HCB) and liquid chlordane exceeded 99.99% in a molten sodium carbonate bath at 900 to 1000°C with a residence time of 0.75 s. For the pilot-scale tests, the concentration of HCB and chlordane in the spent melt was < 1 ppm. The HCl concentration in the off-gas was < 100 ppm. 

Duvall, D. W. Rubey, W. A. "Laboratory Evaluation of High Temperature Destruction of Kepone and Related Pesticides," EPA-600/2-76-299, 1976. 

The pesticide industry generates many concentrated wastes that are considered hazardous wastes. These wastes must be detoxified, pretreated, or disposed of safely in approved facilities. Incineration is a common waste destruction method. Deep well injection is a common disposal method. Other technologies such as wet air oxidation, solvent extraction, molten-salt combustion, and microwave plasma destmction have been investigated for pesticide waste applications. 

Incineration is an estabhshed process for virtually complete destruction of organic compounds. It can oxidize solid, liquid, or gaseous combustible wastes to carbon dioxide, water, and ash. In the pesticide industry, thermal incinerators are used to destroy wastes containing compounds such as hydrocarbons (e.g., toluene), chlorinated hydrocarbons (e.g., carbon tetrachloride). 

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