Treatment of Pesticide-Laden Wastewater by ... - ACS Publications

8 Treatment of Pesticide-Laden Wastewater by Recirculation Through Activated Carbon 1

EDMUND A. KOBYLINSKI , WILLIAM H. DENNIS,JR.,and ALAN B. ROSENCRANCE

Downloaded by UNIV LAVAL on July 11, 2016 | http://pubs.acs.org Publication Date: August 15, 1984 | doi: 10.1021/bk-1984-0259.ch008

U.S. Army Medical Bioengineering, Research and Development Laboratory, Ft. Detrick, Frederick, MD 21701

The Carbolator 35B, a recirculatory carbon filtration system, successfully treated pesticide wastes in both pilot-scale and field tests. In pilot-scale tests, the system was challenged with 400 gallons of water containing 20, 60 and 100 mg/L of each of seven pesticides (baygon, dimethoate, diazinon, ronnel, malathion, dursban, and 2,4-D). The pesticide waste was pumped through the Carbolator and returned to the waste holding tank. The tank contents were analyzed by gas chromatography and thin layer chromatography. A TLC method was developed to perform pesticide analysis in the f i e l d . A simple laboratory recirculating system using 4 l i t e r s of waste was also built to simulate the Carbolator system. A mathematical model was developed to predict the disappearance of the pesticides from the waste holding tank.

Background In the 19th century, various carbons were studied f o r t h e i r ability to d e c o l o r i z e s o l u t i o n s and adsorb compounds from gases and vapors. Commercial a p p l i c a t i o n s o f a c t i v a t e d carbon began e a r l y i n the 20th century. S o l u t i o n s c o n t a i n i n g phenols, a c e t i c a c i d , h e r b i c i d e s , dyes, chlorophenols, cyanide and chromium have been s u c c e s s f u l l y t r e a t e d by carbon adsorption ( 1 . A c t i v a t e d carbon i s s p e c i a l l y t r e a t e d to give a high adsorpt i o n c a p a c i t y . The adsorption c a p a c i t y i s dependent upon surface area. Most of the a v a i l a b l e surface area l i e s w i t h i n the i n t e r n a l pores o f the carbon. One gram o f carbon can have a surface area from 500-1500 m . Concentration gradients between the i n t e r n a l 2

1

Current address: Atlantic Research Corporation, 5390 Cherokee Avenue, Alexandria, VA 22312 This chapter not subject to U.S. copyright. Published 1984, American Chemical Society

Krueger and Seiber; Treatment and Disposal of Pesticide Wastes ACS Symposium Series; American Chemical Society: Washington, DC, 1984.


126

T R E A T M E N T A N D D I S P O S A L O F PESTICIDE WASTES

pores of the carbon and the bulk l i q u i d provide the d r i v i n g force for the d i f f u s i o n of the contaminant i n t o the carbon pores which c o n t r o l s the o v e r a l l r a t e of contaminant removal. The bulk l i q u i d i s defined as that p o r t i o n of f l u i d f a r enough away from the p a r t i c l e surface to not have a c o n c e n t r a t i o n g r a d i e n t . The r a t e of d i f f u s i o n w i t h i n the pore i s set by the type of carbon, geometry of the pore and degree of a c t i v a t i o n . Once a type of carbon i s chosen, only the rate of d i f f u s i o n from the bulk l i q u i d to the l i q u i d boundary surrounding the carbon p r i o r to e n t e r i n g the pores can be c o n t r o l l e d . The l i q u i d boundary l a y e r i s defined as that s e c t i o n of l i q u i d that has a c o n c e n t r a t i o n g r a d i e n t . The thickness of the boundary l a y e r i s a f f e c t e d by turbulence and i s compressed during periods of h i g h turbulence. Several methods can be used to expose a l i q u i d waste to a c t i v a t e d carbon. The batch s l u r r y method i s the simplest. A c t i v a t e d carbon i s added to a batch volume of l i q u i d waste and i s allowed to stand q u i e s c e n t l y . In t h i s case, the boundary l a y e r s t r e t c h e s from the carbon surface at the bottom of the tank to the l i q u i d surface r e s u l t i n g i n a very slow d i f f u s i o n r a t e . The d i f f u s i o n r a t e can be g r e a t l y a c c e l e r a t e d by a g i t a t i o n . Mixing w i l l compress the boundary l a y e r and increase the c o n c e n t r a t i o n d r i v i n g f o r c e . The carbon can be separated by decanting the l i q u i d . This method r e q u i r e s a long h o l d i n g time but i s not manpower i n t e n s i v e . Downflow through packed columns i s another c o n t a c t i n g process. T h i s type of contact can handle high flow r a t e s but the waste stream cannot c o n t a i n large q u a n t i t i e s of suspended m a t e r i a l s . The suspended s o l i d s w i l l c l o g the column and induce a high pressure drop through the column. This process r e q u i r e s frequent backwashing. Upflow expanded bed carbon columns are a t h i r d c o n t a c t i n g process. The l i q u i d waste enters the bottom of the carbon column and expands the carbon bed. Higher suspended s o l i d s c o n c e n t r a t i o n s can be handled i n t h i s system because of the greater d i s t a n c e between p a r t i c l e s i n an expanded bed. Both the upflow and downflow carbon adsorption systems can be operated i n a once through mode or i n a r e c i r c u l a t i o n mode. In a once through mode, the carbon column e f f l u e n t must be cont i n u o u s l y monitored f o r breakthrough of the contaminant from the carbon bed. This r e q u i r e s considerable lab support. The monitoring requirements f o r a r e c i r c u l a t i o n system are c o n s i d e r a b l y l e s s than for a once through system because of the batch treatment aspects i n a r e c i r c u l a t i n g system. The r e c i r c u l a t i n g system w i l l make l e s s e f f i c i e n t use of the carbon charge. The carbon charge i n a r e c i r c u l a t o r y system cannot be allowed to become saturated because of the low c o n c e n t r a t i o n d r i v i n g force and a lack of a v a i l a b l e a d s o r p t i o n s i t e s w i l l tend to g r e a t l y increase the treatment time. In a once through system, the i n i t i a l s e c t i o n s or columns of carbon c o n t i n u a l l y see a high p e s t i c i d e c o n c e n t r a t i o n and can become saturated without h u r t i n g the o v e r a l l system e f f i c i e n c y . As each


8.

KOBYLINSKI ET AL.

Recirculation Through Activated Carbon

127

column i s s a t u r a t e d , i t can be removed from s e r v i c e . The next column i n the s e r i e s w i l l then become the f i r s t column. Replacement carbon columns would be placed at the end of the column s e r i e s . Each column i n a once through system can be run u n t i l saturated, thereby making complete use of the carbon charge.


Introduction The d i s p o s a l of p e s t i c i d e - l a d e n wastewater produced by small generators, which i n c l u d e commercial and government p e s t i c i d e a p p l i c a t o r s , i s a current problem. According to P u b l i c Law 89-272 (Resource Conservation and Recovery A c t ) , the r e s p o n s i b i l i t y f o r the proper d i s p o s a l of hazardous wastes l i e s with the waste generator. Good management of the q u a n t i t y of p e s t i c i d e s o l u t i o n s prepared w i l l r e s u l t i n small waste volumes, however, the bulk of the waste produced w i l l come from the c l e a n i n g of p e s t i c i d e a p p l i c a t i o n equipment and from the r e q u i r e d r i n s i n g of p e s t i c i d e c o n t a i n e r s , e s p e c i a l l y 55-gallon drums. Carbon a d s o r p t i o n o f f e r s a simple and inexpensive s o l u t i o n to clean-up of these waste pesticides. Recognizing the. p o t e n t i a l h e a l t h and p o l l u t i o n problems r e s u l t i n g from the o p e r a t i o n of a pest c o n t r o l f a c i l i t y , the U.S. Army T r a i n i n g and D o c t r i n e Command (TRADOC) designed and b u i l t a pest c o n t r o l f a c i l i t y at F t . E u s t i s , V i r g i n i a , to meet a l l c u r r e n t and a n t i c i p a t e d h e a l t h and environmental r e g u l a t i o n s regarding such f a c i l i t i e s . A common drainage system l i n k s the p e s t i c i d e mixing room, storage room and outdoor washdown area to a sump. The outdoor washdown area was designed i n such a way so as to minimize the amount of rainwater e n t e r i n g the drainage system. The l i q u i d waste c o l l e c t e d i n the sump i s pumped i n t o a storage tank f o r e i t h e r treatment or d i s p o s a l . P r i o r to c o n s t r u c t i o n of the F t . E u s t i s pest c o n t r o l f a c i l i t y , TRADOC requested the U.S. Army Medical B i o e n g i n e e r i n g Research and Development Laboratory (USAMBRDL) to i n v e s t i g a t e the f e a s i b i l i t y of using an a c t i v a t e d carbon f i l t r a t i o n / a b s o r p t i o n system to t r e a t the p e s t i c i d e - l a d e n wastewater. The f i n a l system design was t o : 1) not be manpower i n t e n s i v e ; 2) not r e q u i r e extensive a n a l y t i c a l monitoring, and 3) be compatible with both the types and q u a n t i t i e s of p e s t i c i d e wastes produced by a t y p i c a l pest c o n t r o l f a c i l t y . The i n i t i a l research was funded j o i n t l y by EPA and TRADOC. An inexpensive commercial carbon f i l t r a t i o n system (Carb o l a t o r ) was found to have c o n s i d e r a b l e p o t e n t i a l i n s o l v i n g the waste treatment problem at pest c o n t r o l f a c i l i t i e s . The C a r b o l a t o r operates by the r e c i r c u l a t i o n of wastewater through a bed of a c t i v a t e d carbon. M a t e r i a l s and Methods Synthetic

Wastewater. Between 1977

and

1981,

samples of waste-


128

T R E A T M E N T A N D DISPOSAL O F PESTICIDE WASTES


waters generated at the pest c o n t r o l f a c i l i t i e s at F t . E u s t i s , Va. and F t . Knox, Ky. , were r e c e i v e d and analyzed to determine the composition of t y p i c a l wastes. In a d d i t i o n , contacts with pest c o n t r o l supervisors were made to determine the types and q u a n t i t i e s of p e s t i c i d e s employed at these s i t e s . From t h i s i n f o r m a t i o n , the types of p e s t i c i d e s that would be used i n the l a b o r a t o r y t e s t i n g of the C a r b o l a t o r system were s e t . P e s t i c i d e s chosen f o r the C a r b o l a t o r t e s t s were c h l o r o p y r i f o s (Dursban), 2,4-D-LVE (low volatile e s t e r ) , D i a z i n o n , Dimethoate (Cygon), Fenchlorphos (Ronnel), Malathion and Propoxur (Baygon). S t r u c t u r e s f o r these p e s t i c i d e s are presented i n F i g u r e 1. Gas Chromatography A n a l y s i s of Water f o r P e s t i c i d e s . A l l analyses for p e s t i c i d e s i n water were done by gas chromatography. Solvents used f o r e x t r a c t i o n were checked by gas chromatography f o r p u r i t y and i n t e r f e r e n c e s and a l l glassware used i n the e x t r a c t i o n was cleaned i n a chromic a c i d / s u l f u r i c a c i d mixture. Standards cons i s t e d of mixtures of v a r i o u s p e s t i c i d e s ( a c t u a l commercial formulations) suspended or d i s s o l v e d i n water. These aqueous standards were e x t r a c t e d i n the same manner as unknown s o l u t i o n s . The standard c o n c e n t r a t i o n s encompassed the c o n c e n t r a t i o n of unknowns to be determined. A standard curve normally c o n s i s t e d of a set of four p e s t i c i d e c o n c e n t r a t i o n s . Blanks were run and an i n t e r n a l standard (eicosane) was used. The i n t e r n a l standard concentration was kept constant f o r a l l analyses. The c o n d i t i o n s for GC a n a l y s i s were guided by the p e s t i c i d e s expected i n the water. For the more complex mixtures, such as those employed i n the s y n t h e t i c waste and those encountered i n the f i e l d , a 6 f t . , 3 percent SE-30 on GAS CHROM Q column s u f f i c e d . A t y p i c a l chromatogram of a complex p e s t i c i d e mixture i s shown i n F i g u r e 2. (2^) Figure 3 shows a flow chart that o u t l i n e s the p r o t o c o l f o r a n a l y s i s both of s y n t h e t i c wastewater and waters encountered i n f i e l d t e s t s at F t . E u s t i s , Va. A n a l y s i s of On-Site Wastewaters f o r P e s t i c i d e s by Thin-Layer Chromatography. A f i e l d method to i d e n t i f y q u a l i t a t i v e l y and semiq u a n t i t a t i v e l y the p e s t i c i d e c o n s t i t u e n t s of a p e s t i c i d e - l a d e n wastewater was developed. The f i e l d method was developed u s i n g t h i n - l a y e r chromatography (TLC). TLC gives a presumptive t e s t f o r the presence of s p e c i f i c p e s t i c i d e s and w i t h i n 30 minutes an estimate of t h e i r c o n c e n t r a t i o n s . TLC may a l s o r e v e a l the presence of unknown substances. The f i e l d a p p l i c a t i o n of t h i n - l a y e r chromatography r e q u i r e s a s k i l l e d chemist, but no expensive equipment. The f o l l o w i n g p r o t o c o l d e s c r i b e s the o n - s i t e use of TLC. Twice e x t r a c t a 200 mL a l i q u o t of the wastewater with 25 mL of CH2CI2 i n a 250 mL separatory funnel. Combine both CH2CI2 e x t r a c t s and add a few grams of anhydrous Na2S04 to absorb moisture. Pour a p o r t i o n of the CH2CI2 e x t r a c t i n t o a 20 mL g l a s s v i a l and allow the CH2CI2 to evaporate i n the open a i r . As the CH2CI2 evaporates, add more of the e x t r a c t u n t i l the e n t i r e CH2CI2 e x t r a c t has been


8.

KOBYLINSKI ET AL.

COMMON


ALTERNATE

NAME

NAME

Chlorpyrlfos

Dursban

CHEMICAL

STRUCTURE

NAME

0,0-dlethy Ι-0-(3,5,βtrlchloro-2-pyrldyl)

(EtO)

2


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ieooctyleater

of

.

2,4-dichlorophenoxy- , acetic acid

V

CH CI~C C~CI | || £0-C. C-CI Η Ν S 0

/

0,0-dl*thy l-0-( 2-

N^

4-pyrlmldinyl)

-iso
I

O

ι

φ Ο Ν CO vO CO CM

ON

Ο

Ο Ο Ο Ο Ο

Ο

CO νΟ CM >d" rH rH CO CO

o

CM ON

O

VD CO rH

m o

II IO U

ω

>» rH rQ -H 4J (U CO • rH rH 0) 0J Ν

CCOO 4J CJ

•

S

o o o o o o CO vO CM v£> m rH CO CM

CO


KOBYLINSKI ET AL.



8.

Figure 5. C a r b o l a t o r p i l o t t e s t 2 p e s t i c i d e removal c u r v e s . Reproduced with permission from Ref. 2. Copyright 1983, Marcel Dekker, Inc.


137

138

T R E A T M E N T A N D D I S P O S A L O F PESTICIDE WASTES

Table I I .

E f f i c i e n c y Factors P i l o t Tests

I n i t i a l P e s t i c i d e Concentration, mg/L 20 60 100

Pesticide


(k) C a l c u l a t e d from Carbolator

Baygon Dimethoate Diazinon Ronnel Malathion Dursban 2,4-D (LVE)

0 0 0 0 0 0 0

83 69 53 64 61 62 56

0 0 0 0 0 0 0

Return

81 47 44 43 43 43 40

0 0 0 0 0 0 0

32 33 26 20 29 40 16

Flow

Stirrer

Figure 6.

Bench-scale carbon r e c i r c u l a t o r y system (3_).



8.

KOBYLINSKI ET AL.


139

i n t o a 5 L Erlenmeyer f l a s k c o n t a i n i n g 4 L o f tap water a t room temperature. While t h i s mixture i s being s t i r r e d , p l a c e the wetted carbon (100 g dry weight) i n t o the g l a s s column. P r i o r to use, the carbon was soaked i n water f o r 24 hours. Glass wool or a f r i t can be used to r e t a i n the carbon bed. Clean water (about 500 mL) i s passed upward through the carbon bed (back washing) t o remove carbon f i n e s . The water i s then drained from the carbon column and a connection i s made between the s t i r r e d r e s e r v o i r and the bottom of the carbon column through a p e r i s t a l t i c pump. A one-hole neoprene stopper i s placed i n the top o f the g l a s s column. A rubber hose c a r r y s the wastewater from the top o f the column back to the 5 L c o n t i n u o u s l y mixed f l a s k . The pump i s turned on and adjusted to the d e s i r e d flow, 300 mL/min. When the water has passed the top o f the carbon bed, the carbon column i s tapped to d i s l o d g e a i r pockets. When the water begins to s p i l l back i n t o the r e s e r v o i r , a timer i s s t a r t e d ; t h i s i s t . P r i o r to s t a r t i n g the pump, an a l i q u o t (3 mL) o f the t e s t water i s removed from the f l a s k . T h i s sample i s used to prepare a standard curve from which w i l l be d e r i v e d the conc e n t r a t i o n o f p e s t i c i d e s i n the r e s e r v o i r . At v a r i o u s times d u r i n g t h i s r e c i r c u l a t i o n , 1 mL, 5 mL, or 10 mL a l i q u o t s are removed from the r e s e r v o i r and placed i n t o screw cap ( t e f l o n - l i n e d caps) tubes c o n t a i n i n g 1 mL o f methylene c h l o r i d e (CH2CI2) that i s spiked with 20 ppm o f eicosane ( i n t e r n a l standard). The aqueous sample was e x t r a c t e d with the 1 mL o f CH2CI2 and t h i s e x t r a c t was analyzed by gas chromatography (FID). Table I I I presents the changes i n p e s t i c i d e c o n c e n t r a t i o n f o r a bench-scale t e s t run. The column was charged with 100 g of Calgon F-300 granular a c t i v a t e d carbon. The data are presented g r a p h i c a l l y i n F i g u r e 7. I t can be seen that 100 grams o f carbon was able to remove the p e s t i c i d e c o n c e n t r a t i o n s to l e s s than 1 mg/L f o r 2,4-D and to below d e t e c t i o n l i m i t s f o r the other s i x p e s t i c i d e s w i t h i n 8 hours under the given c o n d i t i o n s . Furthermore, both baygon and dimethoate c l o s e l y f o l l o w the theoret i c a l e x p o n e n t i a l curve i n d i c a t i n g that these substances must be absent i n the e f f l u e n t from the carbon column a f t e r one pass. Q

E f f i c i e n c y f a c t o r s f o r the bench s c a l e t e s t s have been c a l c u l a t e d and are presented i n Table IV. The k v a l u e s i n Table IV are g e n e r a l l y higher than the values presented i n Table I I f o r the p i l o t t e s t at 100 mg/L o f each p e s t i c i d e . The bench-scale and p i l o t - s c a l e systems were loaded as f o l l o w s : 1) the q/v r a t i o s were 0.016 min"l f o r the p i l o t t e s t s and 0.075 min~l f o r the bench-scale t e s t s and 2) the r a t i o o f carbon to g a l l o n s of waste (which r e l a t e s to the mass o f p e s t i c i d e s at a given e q u i v a l e n t c o n c e n t r a t i o n ) was 0.208 l b . c a r b o n / g a l l o n o f water f o r the bench-scale t e s t s and 0.1125 l b . carbon/ g a l l o n o f waste f o r the p i l o t t e s t s . The f l u i d v e l o c i t y through the open column c r o s s - s e c t i o n a l area i s 19.7 cm/min f o r the bench-scale t e s t s and 8.3 cm/min f o r the p i l o t t e s t s . T h i s shows that the system l o a d i n g has a l a r g e e f f e c t on the removal e f f i c i e n c y . I f the bench-scale and p i l o t - s c a l e system were operated under the same loading c o n d i t i o n s , then the e f f i c i e n c y f a c t o r s would be comparable to the a c t u a l C a r b o l a t o r system.


T R E A T M E N T A N D DISPOSAL O F PESTICIDE

or»»r>»vom
-σ Ο > r Ο

Ό 53

α

>

m -Ζ Η

H m

I

KOBYLINSKI ET AL.



8.

Figure 10. P e s t i c i d e removal curves f o r the September 1981 carbolator f i e l d test ( 2 j .


149


150

TREATMENT A N D DISPOSAL OF PESTICIDE WASTES

Table V I I I .

E f f i c i e n c y Factors C a l c u l a t e d f o r the September 1981 C a r b o l a t o r F i e l d Test Pesticide Dimethoate Malathion Baygon Diazinon Dursban 2,4-D LVE g V

= =

k 0..41 3..47 0,.50 0,.40 0,.29 0,.29

5.82 gpm 410 g a l l o n s


8.

KOBYLINSKIETAL.


151

Literature Cited 1. 2.


3.

DeRenzo, D.J., "Unit Operations for Treatment of Hazardous Industrial Wastes," Noyes Data Corporation, 1978. Dennis, W.J. J r . and Kobylinski, E.A., J. Environ. Sci. Health, 1983, B18(3), 317-331. Dennis, William Η . , Jr.; Wade, Clarence W.R.; Kobylinski, Edmund Α . , and Rosencrance, Alan B., "Treatment of PesticideLaden Wastewaters from Army Pest Control F a c i l i t i e s by Activated Carbon F i l t r a t i o n Using the Carbolator Treatment System," Technical Report 8203, U.S. Army Medical Bioengineering Research and Development Laboratory, Frederick, MD., August 1983.

RECEIVED February 13, 1984


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