Removal of 2,3,7,8-Tetrachlorodibenzo-p-dioxin from Waste Water

Chapter 22

Removal of 2,3,7,8-Tetrachlorodibenzo-p-dioxin from Waste Water and Well Water Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 28, 2018 | https://pubs.acs.org Publication Date: April 24, 1987 | doi: 10.1021/bk-1987-0338.ch022

Coagulation and Flocculation with Aluminum Salts Leland Marple, Dale Dei Rossi, and Lewis Throop Syntex Analytical and Environmental Research, Syntex (USA), Inc., 3401 Hillview Avenue, Palo Alto, CA 94303

At various times, water in a wastewater lagoon contained several parts per trillion 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin). A process was developed for the removal of trace amounts based on coagulation and flocculation with aluminum salts. On site treatment utilized a batch process in which suspended solids were coagulated with 1200 mg/1 aluminum sulfate. A polymer modified alum flocculation process was developed for the removal of dioxin from well water. The modification of the floc surface by the adsorption of an uncharged, high molecular weight polymer intensifies the adsorption of dioxin on the floc.

One o f t h e m a j o r p r o b l e m s i n v o l v e d i n t h e r e m e d i a t i o n o f t h e D i o x i n c o n t a m i n a t e d s u r f a c e impoundment ( l a g o o n ) d i s c u s s e d e a r l i e r ( 1 ) was the treatment o f the water t o i n s u r e complete removal o f any 2 , 3 , 7 , 8 - t e t r a c h l o r o d i b e n z o - p - d i o x i n ( D i o x i n ) t h a t may b e p r e s e n t . I n i t i a l l y , s u s p e n d e d m a t t e r was removed b y f i l t r a t i o n t h r o u g h g r o u n d c o r n c o b s , and r e s i d u a l o r g a n i c s were removed b y t r e a t m e n t w i t h a c t i v a t e d carbon. A l t h o u g h t h i s t r e a t m e n t was e f f e c t i v e , t h e p r o c e s s i n g time p e rb a t c h coupled w i t h groundwater seepage and p e r i o d s o f heavy r a i n f a l l prolonged t h e drainage o f t h e lagoon f o r over a year. The s e l e c t i v e r e m o v a l o f v e r y l o w l e v e l s o f d i o x i n f r o m l a r g e v o l u m e s o f p r o c e s s w a s t e w a t e r h a s become a c o n c e r n t o a number o f companies and m u n i c i p a l i t i e s . V e r y l i t t l e h a s b e e n r e p o r t e d o n how d i o x i n behaves i n c o n v e n t i o n a l w a t e r t r e a t m e n t p r o c e s s e s ( 2 - 3 ) . The work o f T h e b a u l t , Cases, and F i e s s i n g e r suggested t h a t alum f l o c c u l a t i o n would be m a r g i n a l l y e f f e c t i v e f o r t h e removal o f dioxin. Our n e e d t o remove up t o s e v e r a l p a r t s p e r t r i l l i o n d i o x i n from water i nt h elagoon prompted us t o e v a l u a t e f l o c c u l a t i o n as a f a s t e r a n d more c o s t e f f e c t i v e t r e a t m e n t f o r d i o x i n r e m o v a l .

0097-6156/87/0338-0286$06.00/0 © 1987 American Chemical Society

Exner; Solving Hazardous Waste Problems ACS Symposium Series; American Chemical Society: Washington, DC, 1987.

22.

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Removal of TCDD from Waste Water and Well Water 287

Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 28, 2018 | https://pubs.acs.org Publication Date: April 24, 1987 | doi: 10.1021/bk-1987-0338.ch022

A s i t t u r n e d o u t , d i o x i n was r e a d i l y r e m o v e d b y a l u m f l o c c u l a t i n g i n t h e presence o f suspended o r g a n i c m a t t e r . The s u c c e s s f u l t r e a t m e n t o f l a g o o n w a t e r p r o m p t e d w o r k o n two r e l a t e d problems. F i r s t l y , we n e e d e d t o f i n d a way t o d e w a t e r t h e a s p h a l t u m l i k e l a g o o n s l u d g e , a n d s e c o n d l y , we n e e d e d t o f i n d a way t o t r e a t w e l l w a t e r , h a v i n g l i t t l e suspended s o l i d s , t o remove d i o x i n t h a t might be p r e s e n t . T h i s paper d e s c r i b e s o u r e x p e r i m e n t a l work on these problems and a p p l i c a t i o n o f o u r f i n d i n g s t o treatment a t t h e plant site. EXPERIMENTAL The amount o f a l u m i n u m n e e d e d t o p r o d u c e r a p i d f l o c c u l a t i o n o f l a g o o n w a t e r w i t h a s u s p e n d e d s o l i d s c o n t e n t o f a b o u t 3 2 0 0 ppm was d e t e r m i n e d b y 100 m l j a r t e s t s . A O.002 u C i s p i k e o f 14-C d i o x i n ( K o r I n c . ) was a d d e d t o t h e w a t e r a n d e q u i l i b r a t e d f o r 2 h o u r s before flocculation. Ammonium s u l f a t e , 5 0 0 ppm, w a s a d d e d t o i n c r e a s e t h e i o n i c s t r e n g t h and promote c o a g u l a t i o n . The b u f f e r c a p a c i t y o f t h e w a t e r was s u f f i c i e n t t o p r e c i p i t a t e t h e a l u m i n u m a d d e d , a n d t h e f i n a l pH o f t h e w a t e r was a b o u t 8. T h e a m o u n t o f d i o x i n s p i k e r e m a i n i n g i n s o l u t i o n was d e t e r m i n e d b y c e n t r i f u g i n g t h e s a m p l e , w i t h d r a w i n g a 50 m l a l i q u o t o f t h e c l e a r s u p e r n a t a n t a n d e x t r a c t i n g t h e d i o x i n w i t h hexane. T h e h e x a n e e x t r a c t was r e d u c e d i n volume i n a r o t a r y e v a p o r a t o r , then t r a n s f e r r e d t o a g l a s s s c i n t i l l a t i o n v i a l along w i t h 5 u l of n-tetradecane. The e x t r a c t was r e d u c e d t o n e a r d r y n e s s w i t h a s t r e a m o f n i t r o g e n , d i l u t e d w i t h s c i n t i l l a t i o n f l u i d , then counted i n a Packard T r i C a r b s c i n t i l l a t i o n counter. T h e f l o c c u l a t i o n p r o c e s s was s c a l e d u p t o t r e a t 2 0 , 0 0 0 g a l l o n s per batch. The s u p e r n a t a n t f r o m e a c h b a t c h was a n a l y z e d f o r d i o x i n , then t r e a t e d w i t h a c t i v a t e d carbon f o r removal o f r e s i d u a l o r g a n i c s The s e t t l e d f l o e w a s r e t u r n e d t o t h e l a g o o n f o r d e w a t e r i n g . The c o a g u l a t i o n o f l a g o o n s l u d g e b y l i m e was f o l l o w e d b y a simple j a rtest. A 40 g s a m p l e o f s l u d g e was m i x e d w i t h w a t e r t o b r i n g t h e v o l u m e t o 2 0 0 m l . I n c r e m e n t s o f O.10 g c a l c i u m o x i d e w e r e added and mixed w e l l . The m i x t u r e was a l l o w e d t o s e t t l e f o r 5 minutes a f t e r each a d d i t i o n , and t h e e x t e n t o f c o a g u l a t i o n e s t i m a t e d from t h e c l a r i t y o f t h e supernatant. The d e w a t e r i n g o f c o a g u l a t e d s l u d g e was d e m o n s t r a t e d b y b u i l d i n g a 4 i n c h b y 6 f o o t c o l u m n i n 12-6 i n . i n c r e m e n t s o v e r a p e r i o d o f 9 d a y s . The l i m e was a d d e d d i r e c t l y t o t h e s l u d g e and m i x e d b y i n v e r s i o n o f t h e c o n t a i n e r . The c o a g u l a t e d s l u d g e was r e t a i n e d b y a 2 i n c h b e d o f a c t i v a t e d c a r b o n h e l d i n place by a p e r f o r a t e d s t a i n l e s s s t e e l screen. Water d r a i n i n g f r o m t h e c o l u m n was p o o l e d u n t i l t h e l a s t a d d i t i o n was made, t h e n i t w a s c o l l e c t e d o n a d a i l y b a s i s . The r e m o v a l o f d i o x i n f r o m w a t e r b y m o d i f i e d a l u m f l o c c u l a t i o n w a s m o n i t o r e d b y t h e d i s a p p e a r a n c e o f a O.08 u C i s p i k e o f 3-H l a b e l e d d i o x i n ( o b t a i n e d f r o m A. P o l a n d , r e p u r i f i e d b y s i l i c a c o l u m n chromatography) i n j a r type experiments. A c o n v e n t i o n a l uncharged G a r r a t t - C a l l a h a n p o l y m e r #7882 was u s e d f o r f l o e m o d i f i c a t i o n . The l a b e l e d d i o x i n s p i k e , d i s s o l v e d i n hexane-methylene c h l o r i d e , 80:20, was i n t r o d u c e d i n t o 2 0 0 m l o f w a t e r i n s e v e r a l w a y s . T h e s p i k e was a d d e d d i r e c t l y t o t h e w a t e r , i t was a d d e d t o w a t e r c o n t a i n i n g t h e


SOLVING HAZARDOUS WASTE PROBLEMS

288


m o d i f y i n g p o l y m e r , a n d i t was e v a p o r a t e d a s a f i l m o n t h e i n s i d e o f the beaker used t o h o l d t h e water sample p r i o r t o f l o c c u l a t i o n . A f t e r t h e a l u m was a d d e d , t h e w a t e r was f l a s h m i x e d f o r two m i n u t e s , then s t i r r e d s l o w l y f o r 5 minutes w h i l e t h e f l o e formed. The f l o e was a l l o w e d t o s e t t l e f o r 15 m i n u t e s , t h e n t h e s u p e r n a t a n t w a s a n a l y z e d f o r d i o x i n b y w i t h d r a w i n g a 50 m l a l i q u o t , e x t r a c t i n g t h e d i o x i n w i t h hexane, a n dw o r k i n g up t h e e x t r a c t a s d e s c r i b e d above.

RESULTS/DISCUSSION The r e m o v a l o f 14-C d i o x i n f r o m l a g o o n w a t e r b y f l o c c u l a t i o n v a r y i n g amounts o f aluminum f o l l o w e d b y c e n t r i f u g a t i o n i s i l l u s t r a t e d i n Table I .

Table

I.

with

R e m o v a l o f 14-C D i o x i n s p i k e f r o m L a g o o n W a t e r b y F l o c c u l a t i o n w i t h Aluminum S a l t s

A1C1

3

Alum

4 4 ppm A l 87 87 100 130

99.8 99.7 99.7 99.6

89 ppm A l 89

98.5 99.5

(u) unmeasured a s c o a g u l a t i o n was i n c o m p l e t e

The r e m o v a l was c a l c u l a t e d f r o m t h e c o u n t s r e m a i n i n g i n s o l u t i o n compared t o t h e counts added t o t h e system. Although there i s very l i t t l e i n f o r m a t i o n i n the l i t e r a t u r e on removal o f c h l o r i n a t e d o r g a n i c s b y alum o r l i m e f l o c c u l a t i o n , o u rr e s u l t s a r e c o n s i s t e n t with available data. F o r example, S a l e h , L e e a n d W o l f ( 4 ) removed a b o u t 9 5 % o f c o m b i n e d DDT i s o m e r s f r o m a n a c t i v a t e d s l u d g e e f f l u e n t u p o n c o a g u l a t i o n / f l o c c u l a t i o n w i t h a 2 3 ppm/165ppm l i m e / a l u m mixture. One w o u l d e x p e c t a g r e a t e r a d s o r p t i o n o f d i o x i n c o m p a r e d t o DDT, o w i n g t o t h e l o w e r w a t e r s o l u b i l i t y o f d i o x i n . Scale-up o f the treatment process proceeded smoothly. Table I I summarizes the l e v e l s o f d i o x i n found i n the supernatant f o r batches processed a t the plant s i t e . While l o wl e v e l s o f other s o l u b l e o r g a n i c s , such as mixed x y l e n e s , ethylbenzene and toluene, are a l s o adsorbed by the f l o e , data are not a v a i l a b l e f o r t h e i r removal a t the s i t e . Since the major d i f f e r e n c e , i n p r i n c i p l e , between water i n t h e l a g o o n a n d t h e s l u d g e i n t h e b o t t o m was t h e p e p t i z e d s o l i d s c o n t e n t , c o a g u l a t i o n appeared t o be t h e l o g i c a l r o u t e f o r sludge dewatering. T h i s was d e m o n s t r a t e d b y s u s p e n d i n g a sample i n w a t e r , and t i t r a t i n g s u s p e n s i o n w i t h alum u n t i l t h e s o l i d s c o a g u l a t e d . S i n c e c o a g u l a t i o n w i t h l i m e i s g e n e r a l l y more c o s t e f f e c t i v e t h a n a l u m , we d e t e r m i n e d t h e a m o u n t n e e d e d b y a s i m p l e j a r t e s t . A l t h o u g h t h e c o a g u l a t i o n a p p e a r e d t o b e c o m p l e t e a t 1 % l i m e , we allowed f o r v a r i a t i o n i n sludge composition by u s i n g a 25% excess


22.

MARPLE ET AL.

Removal of TCDD from Waste Water and Well Water


T a b l e I I . Removal o f D i o x i n Flocculation

from Lagoon Water a t P l a n t

Batch #

Influent

021-R-l 021-R-2 022 022 023 024 025 026 027 028-1

3.1

*undetermined, but

ppt

S i t e by

Alum

Effluent O.35

* *

ppt O.17 O.20 O.21 O.17 O.16 O.27 O.93 O.70 O.42

f r o m t h e same s o u r c e a s

021-R-l

f o r the p r e p a r a t i o n o f a d e w a t e r i n g t e s t column. The t o t a l w e i g h t o f t h e t r e a t e d s l u d g e p u t i n t h e c o l u m n was 2 2 . 8 9 K g . Water d r a i n e d f r o m t h e c o l u m n o v e r t h e c o u r s e o f s l u d g e a d d i t i o n a m o u n t e d t o 7.00 Kg, r e p r e s e n t i n g 98% o f the water u l t i m a t e l y d r a i n e d from the bed. D i o x i n c o u l d n o t be d e t e c t e d i n t h e p o o l e d w a t e r s a m p l e , n o r c o u l d i t b e d e t e c t e d (< O.6 p p t ) i n w a t e r s u b s e q u e n t l y d r a i n e d f r o m t h e sludge bunker at the p l a n t s i t e . We d i d n o t e x p e c t t h a t t h e r e m o v a l o f d i o x i n f r o m w e l l and r u n o f f w a t e r by alum c o a g u l a t i o n and f l o c c u l a t i o n w o u l d be e f f e c t i v e , a s t h e r e i s l i t t l e o r no s u s p e n d e d o r g a n i c p h a s e t o a c t as a c a r r i e r f o r d i o x i n . T h i s p r o b l e m was s o l v e d b y a d d i n g a h i g h m o l e c u l a r w e i g h t p o l y m e r t h a t w o u l d b e a d s o r b e d t o a n d c a r r i e d down w i t h the f l o e . P a r t i t i o n o f d i o x i n i n t o t h e p o l y m e r i s so f a v o r e d t h a t p a r t s p e r m i l l i o n l e v e l s o f p o l y m e r s h o u l d remove most o f t h e dioxin. The r e s u l t s o f j a r t e s t s t o f i n d t h e o p t i m u m l e v e l o f p o l y m e r , a t a f i x e d 100 ppm l e v e l o f a l u m i n u m a r e g i v e n i n T a b l e I I I .

Table I I I .

R e m o v a l o f 3-H D i o x i n S p i k e M o d i f i e d Alum F l o c c u l a t i o n

f r o m Tap

Water by

Polymer

C o n e . P o l y m e r , #7882

% D i o x i n Removed a t 100 ppm A l

12.3 18.5 18.5 24.6 24.6 30.8

86.1 92.8 89.0 68.0 73.8 84.6


289

SOLVING HAZARDOUS WASTE PROBLEMS

290

I f one assumes t h a t t h ep a r t i t i o n o f d i o x i n between polymer a n d water i se q u i v a l e n t t o t h ep a r t i t i o n between o c t a n o l and water, t h e amount o f d i o x i n i n s o l u t i o n s h o u l d d r o p b y a t l e a s t 9 4 % . T h e p e n a l t y f o r t h i s process i s an a d d i t i o n a l s o l i d s waste l o a d i n g o f a b o u t 2.5 p o u n d p e r 1 0 0 0 g a l . t r e a t e d w a t e r . The e f f e c t o f i n t r o d u c i n g d i o x i n i n t o t h e s y s t e m b y d i f f e r e n t routes i s given i n TableIV.


T a b l e I V . Summary o f D i o x i n R e m o v a l s b y M o d i f i e d A l u m Method

Solid Dioxin

% Initial Spike Dissolved

% Soluble S p i k e Removed

Flocculations Polymer/Al R a t i o ppm

65

85 25

18/100 0/100

D i o x i n t o Water w i t h Polymer

30

86 93

12/100 18/100

D i o x i n t o Water

60

89 90 75

18/100 18/80 18/80

Residue

The v a r i o u s r o u t e s w e r e u s e d t o a v o i d a r t i f a c t s a r i s i n g f r o m a d s o r p t i o n a t s u r f a c e s i nt h e e q u i l i b r a t i n g system. I ti s clear f r o m t h e s e d a t a t h a t t h e r e m o v a l o f d i o x i n b y a 1 2 - 1 8 ppm p o l y m e r m o d i f i e d alum f l o e was v e r y c l o s e t o 90%. V e r i f i c a t i o n o f t h e r e m o v a l o f d i o x i n b y t h e f l o e was o b t a i n e d b y r e c o v e r i n g t h e f l o e and m e a s u r i n g t h e t r i t i u m a c t i v i t y . T h i s was needed i n o r d e r t o r u l e o u t t h ep o s s i b i l i t y t h a t t h epolymer m e r e l y enhanced t h e l o s s to t h e system. A s i t t u r n e d o u t , t h e amount o f d i o x i n t h a t was t r a p p e d b y t h e f l o e was g r e a t e r t h a n t h a t c a l c u l a t e d from t h e d e c r e a s e i n s o l u b l e d i o x i n i n s o l u t i o n , s o some o f t h e d i o x i n o r i g i n a l l y l o s t t o t h e s y s t e m was r e c o v e r e d b y t h e f l o e . Consequently, s c a l e up o f t h i s p r o c e s s a t t h ep l a n t s i t e h a s t h e p o t e n t i a l o f b e i n g more e f f i c i e n t a t r e m o v i n g d i o x i n f r o m w a t e r t h a n we p r e d i c t f r o m l a b o r a t o r y e x p e r i m e n t s .

LITERATURE CITED

(1)

Forrester, R.F., Marple, L.W. Carson Jr., C.P., in "Solving Hazardous Waste Problems: Dioxins," Exner, J.H., Ed.; ACS Symposium Series No.______, American Chemical Society,

Washington,

D.C. 1987, P.______. (2) (3) (4)

Robeck, C.G., Dostal, K.A., Cohen, J.M., Dreissel, J.F., J. Am. Water Wks. Ass. 1965, 57, 181-199. Thebault, P., Cases, J.M., Fiessinger, F., Water Research 1982, 15, 183-189. Saleh, F.Y., Lee, G.F., Wolf, H.W., Water Research 1982, 16, 479-488.

RECEIVED November 25, 1986


Removal of 2,3,7,8-Tetrachlorodibenzo-p-dioxin from Waste Water

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