8 Developing Technology for Detoxification of Pesticides and Other Hazardous Materials CHARLES J. ROGERS U.S. Environmental Protection Agency, Cincinnati, O H 45268 ROBERT A L L E N U.S. Environmental Protection Agency, Philadelphia, PA 19106
Promising technologies are continuously being developed to reduce the impact o f toxic and hazardous materials (whether liquid, s e m i - l i q u i d , or solid) on the environment. Although i n the past excess materials have been disposed o f by the quickest, e a s i e s t , and most economical means available, a recent increase in the supply o f agricultural chemicals and, more importantly, an increase i n concern for the environment places new emphasis on treatments needed prior to disposal. Specialized techniques investigated by the U.S. Environmental Protection Agency (USEPA) for detoxification o f toxic and hazardous materials include wet oxidation, c h l o r i n o l y s i s , sulfonation, c a t a l y s i s , incineration, micro-wave plasma, encapsulation, and experimental disposal pits that prevent the loss o f unwanted material while allowing biodegradation. The last, a promising technique for treatment o f pesticides used by farmers and agricultural and commercial applicators, i s discussed i n this paper. Pit Disposal o f Excess Hazardous Materials. Ongoing work at Iowa State University includes development o f a simple technique for the disposal o f pesticides l e f t unused i n ground or aerial application operations. At present the safety and effectiveness o f the various disposal systems i n use by a p p l i cators have not been documented to the extent that USEPA can recommend this technique over others. Since 1967, Iowa State University has developed and used a simple p l a s t i c - l i n e d disposal p i t at the Agronomy and A g r i cultural Engineering Research Station near Ames. In 1973, a more sophisticated concrete-lined p i t was constructed at the Horticultural Research Station shown i n Figure 1. There had been no monitoring o f either p i t for effective degradation, possible loss by volatilization, or possible concentration o f hazardous pesticides. To obtain adequate data on the disposal p i t s , a USEPA grant was awarded October 1975 to Iowa State U n i v e r s i t y - - s p e c i f i c a l l y , to evaluate the 0-8412-0433-0/78/47-073-100$05.00/0 This chapter not subject to U.S. copyright. Published 1978 American Chemical Society
8.
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effectiveness of p i t s currently in use and to determine the factors and parameters for improving the technique. Some of the pesticides used at the Horticulture Station and deposited in the specialized p i t are shown in Table I. TABLE I CHEMICALS USED AT HORTICULTURE STATION Small amounts of leftover diluted materials were deposited. Insecticides Carbaryl 50% (sevin) Chlordane 50% Kelthane 35% Pyrethrum 20% Cythion 25% W.P.
Toxophene E.L. (6 lb/gal) Guthion 50% W.P. Lannate 90% Heptachlor 30.2% + Xylene 44%
Herbicides Dacthal 2,4-D Paraquat
Ami ben 23% W.P. Tenoran 50% W.P. Casoron Fungicides
Ben!ate Bravo 6F 54% Benlate Captan
Maneb Zineb Sulfur
The chemical and microbiological studies, although incomplete, have revealed that many of the pesticides disposed in the pits can s t i l l be detected. Tables II and III show pesticide concentrations i n ppm for the horticultural farm disposal p i t as sampled i n March and June of 1977. Microbiological studies also have shown that gram negative bacterial species thrive in the pits and a c t i v e l y degrade selected pesticides. To determine the chemical a l t e r a t i o n of pesticides in the horticultural disposal p i t , a mi ni p i t experiment i s being conducted as part of the larger project by personnel from the Departments of Agricultural Engineering, Agronomy, Bacteriology, Botany and Plant Pathology, Energy and Mineral Resource Research I n s t i t u t e , and Entomology at Iowa State University. The slides for the oral presentation (174th meeting of the American Chemical Society, Chicago, August 30, 1977) were taken April 27, 1977, when pretreatment samples were taken and p e s t i cides were added to the mi ni p i t s .
Endosulfan I I
Endosulfan I
Hexachlorobenzene
Ramrod
Dacthal
Bravo
Guthion
Pesticide
2°
2°
2°
2°
Soil
2
H0
Soil
2
H0
Soil
H
Soil
H
Soil
H
Soil
H
Soil
2
H0
Sample Type
0.46 4583 0.30 411 11.5
2.8 309
0.14 3296 0.24 358 13.9
33.0
57.3 5.1
9.9
0.12 63.7
1.5 74
#1
0.15 19.6
*2 #5
0.22 548
3.8 3767
#7
4.0
6.2
0.13 0.50
29.6
65.7
0.29 104 0.15 66.7
0.16 123
57.7
0.25 202
46.2
1.7
3.4
0.12 3.5
4.7
11.2
0.15 74.8
7.8
11.6
0.20 19
2.9 124
#6
13.0
0.26 489
4.0 3064
0.26 0.28 64 1718
0.52 309
8.1 1784
#4
0.21 0.23 0.35 3548 32 2923
0.03 296
2.1 124
*3
PPM AT VARIOUS SAMPLING POINTS
Amount o f Pesticides In PPM at the H o r t i c u l t u r a l Farm Disposal P i t - March 1977
1.7
2.2
0.11 5.9
11.1
0.31 53
0.23 367
2.1 13
#8
H
Ramrod
Endosulfan II
Endosulfan I
Hexachlorobenzene
2° Soil
Soil
2
H0
2° Soil
H
2° Soil
H
2° Soil
H
Soil
2
H0
2° Soil
H
sample Type
Dacthal
Bravo
Guthion
Pesticide
11.3
0.20
26.6
0.51
25.0
0.11
6.5
0.07
6.9
.11
0.33 10.4
0.03 1.2
15.3
0.57
50 300
155 57
3.2
0.11
9.2
593
916
6.35 .45 1 3376
.28
0.25
96
29
38
118
0.07 7.0
.14
.64
#4
.20
.09 .19
.14
1.7
1.5 0.02 0.02
0.8
0.03
1.0
3.5 0.14
11.0
0.03
0.25
90
45
5.05
485
1.39
28
0.05
.72
.44
#8
0.11 20.0
151
280
30
92
#7
0.26
9-2
159
36
43
78
#6
0.04 4.2
0.17 27.4
32 163
14
67
191
#5
PPM AT VARIOUS SAMPLING POINTS #3
0.08
29
21
200
20
4
.85
.06
452
118
205
#1
*2
Amount of Pesticides i n PPM at the H o r t i c u l t u r a l Farm Disposal P i t - June 1977
DISPOSAL AND DECONTAMINATION OF PESTICIDES
Figure 1. Concrete-lined disposal pit
Figure 2. An overall view of the minipH area
ROGERS AND ALLEN
Figure 3.
Detoxification
of
Pesticides
Closer view of shed and polyvinyl chloride compressed air manifold
DISPOSAL AND DECONTAMINATION OF PESTICIDES
Figure 4. Adding water to a garbage can containing soil (15 kg) to make a total volume of 60 L
ROGERS AND ALLEN
Figure 5.
Figure 6.
Detoxification
of
Pesticides
Closeup of water level gage shown in previous slide
Electric motor and propeller stirrer used to mix soil, water, and pesticide(s) in each garbage can
DISPOSAL AND DECONTAMINATION OF PESTICIDES
Figure 7.
Addition of a wettable powder formulation of carbaryl (see Table II) to Minipit 3E
Figure 8.
Continuation of mixing prior to obtaining a sample for analysis
ROGERS AND ALLEN
Detoxification
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Pesticides
Figure 9. Obtaining samples for analysis: a 4-oz jar with a 2-hole rubber stopper (holes in a vertical position) is moved slowly from top to bottom twice in the process of taking a sample
Figure 10. Addition of emulsifiable concentrate formulation of Alachlor to Minipit 5G
DISPOSAL AND DECONTAMINATION OF PESTICIDES
Figure 11.
Obtaining sample for bacteriological analysis immediately after sampling for chemical analysis
Figure 12. Weather station within a few hundred feet of the minipit area. Weather information will be avaifoble for comparison of the analytical data.
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The mi ni pit experiment consists of f i f t y - s i x (56) t h i r t y (30) gallon polyethylene garbage cans p a r t i a l l y buried in the ground and arranged i n seven 8-can rows (Figure 2). Four rows contain herbicides (alachlor, atrazine, 2,4-D, and t r i f l u r a l i n ) , with one herbicide per row i n d i f f e r e n t amounts and concentrations. Two rows contain i n s e c t i c i d e s (carbaryl and parathion), one per row, again in d i f f e r e n t amounts and concentrations. The l a s t row contains mixtures of a l l six pesticides. The eight garbage cans per row a l t e r n a t e l y contain 300 gram, 0.5% (w/w) and 15 gram, 0.025% (w/w) pesticide samples. The 0.5% (w/w) concentration represents a reasonable, practical application concentration. The 0.025% (w/w) concentration approximates the d i l u t i o n one might obtain by r i n s i n g the tank on equipment used to apply the pesticide. Half of the cans contain 0.1% (w/v) peptone as a nutrient. The contents of half the cans (some with, some without nutrients) are aerated using a small compressor, a polyvinyl chloride manif o l d , and tygon tubing leading to each f r i t t e d glass aerator. The entire area i s protected by a wire fence and warning signs. Garbage can l i d s are kept i n place between sampling periods. Analyses and evaluations for both the minipits and large p i t will be completed by November 1978. It i s expected that the results will show whether a low-cost, improved p i t disposal system can be developed and recommended for wide-scale use i n the disposal of unwanted pesticides. Summary. The pesticide disposal p i t (macro) located at Iowa State University's horticulture station has been in use for seven years. Water and soil samples were analyzed during the 1976-77 growing season for chemical, biological and microbial a c t i v i t y and content. The major finding, as substantiated by chemical and microbiological data, i s that no build-up of pesticide residues in the p i t occurs. Sampling and analyzing of the p i t at various locations revealed that inhomogeneity of pesticide d i s t r i b u t i o n existed. Consequently, minipit experiments were designed to determine trends i n pesticide degradation, and the overall fate of pesticides disposed of in the p i t s . It i s expected that at the conclusion of 1978, s u f f i c i e n t data w i l l be available for f u l l - s c a l e demonstration of t h i s disposal technique. MARCH 23,
1978
