k V A - b U U / Z - Iti-TLY4
December 1976 *
Environmental Protection Technology Series
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RESEARCH REPORTING SERIES Research reports of the Office of Research and Development, U.S. Environmental Agency, have been grouped into five series. These five broad were established to facilitate further development and application of ntal technology. Elimination of traditional grouping was consciously
Environmental Pro
instrumentation;' equipm sources of pollution. This uired for the control and
D WASTE
RESEARCH STAFF
200 S.W. 35 Street Cowallis, Or. 97330
(503)757-4691
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This document is available to the public through the National Technical Information Service, Springfield, Virginia 22161.
EPA 600/ 2 - 7 6-2 94 December 1976
TREATMENT OF EFFLUENT WATERS FROM VEGETABLE OIL REFINING
Donald F. G i l l , Jr. James C. I e l a s e Archer Daniels Midland Co. Decatur, I l l i n o i s 62525
i Grant 12060 FDK
Project Officer C l i f f o r d Risley, Jr.
U. S
. Environmental P r o t e c t i o n Agency Region V Chicago, I l l i n o i s 60606
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY OFFICE OF RESEARCH AND DEVELOPMENT U.S. ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OHIO 45268
DISCLAIMER This r e p o r t has been reviewed by t h e I n d u s t r i a l Environmental Research Laboratory, U.S. Environmental P r o t e c t i o n Agency, and approved f o r pub1 i c a t i o n . Approval does n o t s i g n i f y t h a t t h e contents n e c e s s a r i l y r e f l e c t t h e views and p o l i c i e s o f t h e U.S. Environmental P r o t e c t i o n Agency, n o r does mention o f t r a d e names o r commercial products c o n s t i t u t e endorsement o r recommendation f o r use.
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I
FOREWORD
When energy and material resources a r e extracted, processed, converted, and used, the related pollutional impacts on our environment and even on our health often require that new and increasingly more e f f i c i e n t pol 1u t i o n control methods be used. The Industrial Environmental Research Laboratory - Cincinnati (IERL-Ci ) a s s i s t s i n developing and demonstrating new and improved methodologies that will meet these needs both e f f i c i e n t l y and economically. This report, entitled "Treatment of Effluent Waters from Vegetable O i 1 Refining," presents the development o f a chemical pretreatment method.
Waste management personnel can u t i l i z e the results t o reduce the BOD load up to 71%. The Industrial Pollution Control Division and the project officer can be contacted for further information on the subject.
David G. Stephan Director Industrial Environmental Research Laboratory Cincinnati
iii
ABSTRACT W i t h overloaded municipal f a c i l i t i e s and increasingly r e s t r i c t i v e Federal water qual i ty regulations , i t has become necessary t o r e s t r i c t industrial wasteloads. Vegetable o i l refineries generate a h i g h BOD loading along w i t h a h i g h f a t loading, which makes treatment difficu t. Original loadings w i t h only surface skimning as treatment generated 0.0135 kg BOD5 per kg o i l processed. After the grant period, the load was 0.0019 kg per kg processed f o r a reduction of 86%.
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Major wastewater sources and processes are defined and described. Refinery washwater from the o i l water wash centrifuges was found to be the major contributor of BOD5 and f a t , w i t h barometric cooling tower blowdown and water from acidulation contributing smaller amounts t o the load. A calcium chloride pretreatment for the washwater which reduced the overall BOD5 load by 71% was developed. This was done by the addition of 0.25% by weight calcium chloride t o the washwater and pH adjustment t o between 5 and 6. Further research was done t o devise methods t o further reduce the wastewater loadings t o w i t h i n municipal limits. Dissolved a i r flotation was t r i e d without success. A consultant was retained t o invest i g a t e further chemical preatment. These studies along w i t h the recommended process for f e r r i c chloride and lime treatment are presented.
I t was f e l t by the grantee t h a t the wastewater loads could be reduced t o w i t h i n the municipal limits by making some process modifications, i n creasing production supervision, and i n s t a l l i n g a c l a r i f i e r t o control process upsets. This program resulted in a further reduction of 50% and brought the waste strength t o w i t h i n municipal limits.
Cost f o r the system installed i s $75,000 per year. Revenues from recovered by-products range from $20,000 per year to $180,000 per year , depending on the price of recovered material. This report was submitted i n fulfillment of Grant Number 12060 FDK by the Archer Daniels Midland Company, Decatur, I l l i n o i s , under the partial sponsorship of the U.S. Environmental Protection Agency. This report covers a period from March 1970 t o December 1973.
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CONTENTS
......................... iii Abstract,. . . . . . . . . . . . . . . . . . . . . . . . iv vi Figures . . . . . . . . . . . . . . . . . . . . . . . . . viii Tables.. . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgment . . . . . . . . . . . . . . . . . . . . . . X Introduction . . . . . . . . . . . . . . . . . . . . . . . 1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . 2 Recotnnendations . . . . . . . . . . . . . . . . . . . . . 4 Process D e s c r i p t i o n . . . . . . . . . . . . . . . . . . . 5 Wastewater Sources, Analysis, and Q u a n t i t i e s . . . . . . . 11 Primary Chemical Treatment . . . . . . . . . . . . . . . . 16 T r e a t a b i l i t y Studies and Design Basis . . . . . . . . . . 20 D e s c r i p t i o n and E v a l u a t i o n o f I n s t a l l e d Wastewater . . . . 48 Foreword
Management Faci 1it i e s
........................ Bibliography . . . . . . . . . . . . . . . . . . . . . . .
Appendices
V
68
77
FIGURES Number
Page Soybean p r e p a r a t i o n and o i l e x t r a c t i o n flow diagram ( t y p i c a l L i n c o l n & Decatur)
6
2
O i l r e f i n i n g f l o w diagram
7
3
Deodorization f l o w diagram
4
BOD and COD c o r r e l a t i o n f o r t o t a l West p l a n t eduent
1
.......... .............. ..............
.......................
12
5
Schematic o f major. wastewater sources
13
6
CaC12 water treatment f l o w sheet
19
7
Treatment f l o w diagram d u r i n g water survey
a
West p l a n t r e f i n e r y skimmer e f f l u e n t v a r i a b i l i t y o f 24 h r composite COD and f l o w s
33
West p l a n t r e f i n e r y t r e a t e d skimmer e f f l u e n t settling test results
37
9 10 11 12 13 14 15 16 -1-7 18
......
.............
................. Proposed treatment f a c i 1it y . . . . . . . . . . . . . . Decatur wastewater treatment f a c i l i t y . . . . . . . . . West p l a n t treatment f l o w diagram . . . . . . . . . . . Pounds BOD5 p e r pound o i l processed . . . . . . . . . . Pounds f a t p e r pound o i l processed . . . . . . . . . . C l a r i f i e r pH vs . day ADM Decatur . . . . . . . . . . . Temperature vs . day ADM c l a r i f i e r . Decatur. Illinois . . . . . . . . . . . . . . . . . . . . . . . C l a r i f i e r COD vs . day ADM Decatur . . . . . . . . . . . F a t v5 . day Decatur ADM c l a r i f i e r . . . . . . . . . . . vi
I
......... ...........
10
23
39 49 51 52 53 60
61 62 63
I
Number
Page
................ Walker skimmer . . . . . . . . . . . . . . . . . . . . Lincoln wastewater treatment f a c i l i t y . . . . . . . . Rex wastewater c l a r i f i e r
A- 1
A-2
c- 1 c-2
68
69 71
ADM Lincoln, Nebraska average mg/l f a t vs. month January 1971-March 1972
74
c-3
ADM Lincoln, Nebraska suspended s o l i d s vs. month January 1971-March 1972
75
c-4
ADM Lincoln, Nebraska average l b COD/day vs. month January 1971-March 1972
76
............... ............... ...............
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TABLES
Page
Number Characteristics of Refinery Wastewater Component Streams Grab Samples . . . .
14
2
Extraction Plant Loading
15
3
Laboratory Mashwater COD Reduction by Calcium Chloride Treatment and pH Adjustment
16
4
Wastewater BOD5 Before and After CaCl2 Treatment Installation: East Plant Discharge t o Municipal Sewer
17
1
........ ................
.........
......................... Laboratory COD Reduction w i t h Gas Flotation . . . . .
21
6
Chemical Flocculation Screening Test Results f o r West Refinery Skimmer Effluent
24
7
Chemical Flocculation Results of Samples of West Plant Refinery Skimmer Effluent
30
Laboratory S e t t l i n g Test Results of Refinery Skimmer Effluent
34
5
8 9 10
11 12
13 14 15 ..
16
............
...........
................... Sumnary of Investigative Results . . . . . . . . . . . Summary of Design Basis and Major U n i t Sizes . . . . . Sumnary of Major Equipment Sizes . . . . . . . . . . . Summary of Construction Costs . . . . . . . . . . . . Summary of Annual Estimated Costs . . . . . . . . . . West P l a n t Effluent Analysis . . . . . . . . . . . . . Decatur West Plant BOD5 and Fat Per Pound Oil Processed
.................... C l a r i f i e r COD Reduction . . . . . . . . . . . . . . . viii
35 40
41 45 46 54 56 58
Number
Page
............. .............
17
Decatur C l a r i f i e r Operation
18
Lagoon Operation COD (mg/l)
19
I n s t a l l a t i o n and Operation Costs f o r West Refinery Waste Treatment System
20 21 C-1
...
........... Sumnary o f Treatment Costs . . . . . . . . . . . . . NetCosts . . . . . . . . . . . . . . . . . . . . . . Analysis o f Discharge t o Municipal Sewer . . . . . .
..
ix
64 65 66 66
67 72
ACKNOWLEDGMENTS This study was conducted by t h e Archer Daniels Midland Company, Decatur, I l l i n o i s . The i n i t i a l treatment s t u d i e s were conducted by James I e l a s e under t h e d i r e c t i o n o f R. S. White. I n 1969, James I e l a s e took over d i r e c t i o n o f t h e study. The Roy F. Weston Company o f Chicago, I l l i n o i s , was r e t a i n e d t o i n v e s t i g a t e secondary chemical treatment and t o design a f e r r i c c h l o r i d e and l i m e treatment system. Arnold Johnson, r e f i n e r y p r o j e c t engineer, supervised c o n s t r u c t i o n of t h e c l a r i f i e r and treatment system. Donald G i l l developed t h e o p e r a t i o n procedures and process m o d i f i c a t i o n s a f t e r t h e system was i n s t a l l e d and prepared t h e f i n a l r e p o r t . James Curry a s s i s t e d w i t h t h e a n a l y t i c a l work throughout t h e g r a n t period.
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This r e p o r t was submitted i n f u l f i l l m e n t o f Grant No. 12060 FDK. C l i f f o r d R i s l e y , Jr. was t h e p r o j e c t o f f i c e r d u r i n g t h e g r a n t . David R i c k l e s was t h e a s s i s t a n t p r o j e c t o f f i c e r d u r i n g t h e research and c o n s t r u c t i o n phase. Ronald Eng was t h e a s s i s t a n t p r o j e c t o f f i c e r d u r i n g t h e p r e p a r a t i o n o f t h e f i n a l r e p o r t . He and James Scaief, research r e p r e s e n t a t i v e , C o r v a l l i s , Oregon, provided assistance i n t h e f i n a l r e p o r t preparation. Special r e c o g n i t i o n i s made o f t h e e f f o r t s o f Jack L. Witherow o f t h e Food and Wood Products Branch, C o r v a l l i s F i e l d S t a t i o n , IERL-Cincinnati. M r . George Rey, EPA s t a f f engineer, Washington Headquarters, provided t e c h n i c a l assistance i n t h e e a r l y stages o f the p r o j e c t .
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SECTION I
INTRODUCTION The Archer Daniels Midland Co. , Inc. , processes oilseeds, p r i m a r i l y soybeans. O i l i s s o l v e n t - e x t r a c t e d from t h e seeds and r e f i n e d a t t h r e e l o c a t i o n s - - t w o a t Decatur, I l l i n o i s , and one a t L i n c o l n , Nebraska. The r e f i n i n g of vegetable o i l s generates several wastewater streams t h a t have caused t h e p l a n t s t o exceed acceptable waste s t r e n g t h l i m i t s s e t by t h e i r r e s p e c t i v e municipal a u t h o r i t i e s . The o b j e c t o f t h i s p r o j e c t was t o analyze these waste streams and devise treatment methods by which t h e i r BOD5 and f a t s t r e n g t h c o u l d be reduced t o acceptable l e v e l s . The i n i t i a l problem was t o i d e n t i f y t h e waste streams and t o charact e r i z e t h e wastewater. The second problem was t o determine optimum t r e a t ment f o r each source and f i n a l l y t o implement t h e necessary equipment and procedures. The i n i t i a l i n v e s t i g a t i o n and design was done by ADM i n c o n j u n c t i o n w i t h a c o n s u l t i n g f i r m . These i n v e s t i g a t i o n s a r e described i n Sections V, V I , and V I I . Because o f s i g n i f i c a n t process m o d i f i c a t i o n s described i n Section V I I I , i t was determined t h a t some of t h e process recommendations would n o t be necessary. P r o v i s i o n s were made f o r t h e i r f u t u r e i n s t a l l a t i o n i f t h e y proved t o be necessary.
A d e s c r i p t i o n o f equipment i n s t a l l e d and r e s u l t s obtained a r e cont a i n e d i n Section V I I I .
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SECTION I 1 CONCLUSIONS The wastewater survey done a f t e r t h e calcium c h l o r i d e system was i n s t a l l e d determined t h a t f o r a soybean processing f a c i l i t y , t h e r e f i n e r y produces approximately 90% of t h e wasteload and t h e e x t r a c t i o n p l a n t cont r i b u t e s o n l y about 10%. O f t h e r e f i n e r y wastewaters, t h e washwater i s the l a r g e s t source o f BOD5 and f a t . For a f a c i l i t y processing 385,500 kg (850,000 l b ) p e r day o f o i l , t h i s stream c o n t r i b u t e s 450 t o 22,700 kg (1000 t o 50,000 l b ) per day o f BOD5 and f a t i n t h e form o f water s o l u b l e soaps. Greasy c o o l i n g water can c o n t r i b u t e 340 kg (750 l b ) o f f a t and BODS. Acid water c o n t r i b u t e s approximately 30 kg (70 l b ) o f f a t and 1800 kg (4000 l b ) o f BOD5 p e r day. F l o o r washings and c a r washings can c o n t r i b u t e s i g n i f i c a n t and h i g h l y v a r i a b l e loadings. Any o f these sources can c o n t r i b u t e many times t h e normal l o a d i n g under c o n d i t i o n s where t h e process i s upset o r uncontrolled. Treatment o f t h e washwater w i t h 0.25% by weight calcium c h l o r i d e r e s u l t e d i n an o v e r a l l r e d u c t i o n o f 71% o f t h e BODS, from 0.0135 t o 0.0039 kg BOD5 per kg o i 1 processed. Process m o d i f i c a t i o n s , increased process c o n t r o l , and a c l a r i f i e r r e s u l t e d i n a f u r t h e r r e d u c t i o n i n t o t a l l o a d o f 50% o f b o t h t h e f a t and COD. A g r e a t e r r e d u c t i o n would have been obtained had t h e p l a n t n o t s t a r t e d t o r e f i n e corn o i l a t approximately t h e same time t h e c l a r i f i e r was s t a r t e d . I n s t a l l a t i o n o f t h e c l a r i f i e r i n L i n c o l n , where corn o i l i s n o t r e f i n e d , r e s u l t e d i n a r e d u c t i o n o f 65% o f t h e COD and f a t . The o v e r a l l r e d u c t i o n i n Decatur f o r b o t h t h e calcium c h l o r i d e and c l a r i f i e r was 86%, from 0.0135 kg BOD5 p e r kg o i l processed t o 0.0019 kg BOD5 per kg o i l processed. Laboratory s t u d i e s i n d i c a t e d t h a t secondary chemical treatment w i t h f e r r i c c h l o r i d e and l i m e would r e s u l t i n a r e d u c t i o n o f 85% o f t h e f a t and 65% o f t h e COD over t h e calcium c h l o r i d e treatment. This would be an o v e r a l l r e d u c t i o n o f 95% o f t h e f a t and 90% o f the COD. The calcium c h l o r i d e treatment system was i n s t a l l e d i n 1970 a t a c o s t Treatment c o s t based on 10 years s t r a i g h t l i n e d e p r e c i a t i o n i s of $25,000. $32,308 p e r year. The system removes approximately 1206 kg (2660 l b ) This i s a c o s t of 2.346 per day f a t and 3736 kg (8236 l b ) p e r day BOD per kg (1.066 p e r l b ) BOD5 and 7.286 p e r kg ( .34 per l b ) f a t removed.
3
.
. The c l a r i f i e r was i n s t a l l e d i n 1971 a t a c o s t o f $96,000. Annual T o t a l treatment d e p r e c i a t i o n cost, based on 5.5% p e r year, i s $5,367. c o s t f o r t h e c l a r i f i e r i s $42,961 p e r year. The system removes approxi-
2
mately 778 kg (1716 l b ) per day BOD5 and 190 kg (420 l b ) per day f a t . This i s a c o s t of 61.954 per kg (28.14 per l b ) f a t and 15.154 per kg (6.874 per 1 b) BOD5 removed. The net c o s t f o r the treatment system i s 14.774 per kg (6.74 per l b ) f a t removed, 4.564 per kg (2.074 per l b ) BOD5 removed, and 364 per 1000 l i t e r ($1.36 per 1000 g a l ) water t r e a t e d . This c o s t i s o f f s e t by revenue from recovered o i l t h a t can be sold. The price of this o i l has v a r i e d over the g r a n t period from 8.84 t o 39.74 per kg (44 t o 184 per l b ) . This results i n a net treatment c o s t t h a t has v a r i e d from 254 per 1000 l i t e r (954 per 1000 g a l ) t o a gain of 514 per 1000 l i t e r ($1.93 per 1000 g a l ) . On a b a s i s of o i l processed, this i s ,0326 per kg (.0154 per 1b) o i l processed t o a gain of ,0634 per kg (.0284 per 1b) o i l processed. I n s t a l l a t i o n of the ferric c h l o r i d e and lime treatment system i s estimated t o c o s t $100,300 per y e a r compared t o $43,000 f o r the system i n s t a l l e d . The estimated f a t recovered would be approximately 324 kg (714 l b ) per day a t a c o s t of $275 per day, or 84.94 per kg (38.54 per l b ) f a t , w h i c h is 37% higher than the i n s t a l l e d treatment.
3
SECTION I11 RECOMMENDATIONS Further research should be done t o develop uses for and modifications of corn lecithin to reduce the wasteload from refining corn o i l . Additional study i s a l s o needed t o determine the e f f e c t the f e r r i c chloride and lime treatment system would have on the reduced waste load compared t o the load a t the time the secondary chemical treatment was done. A further major reduction i n BOD5 would result i n the development of a good treatment system for the acid liquor. This was not an important consideration d u r i n g this g r a n t period because a f t e r the development o f the calcium chloride treatment f o r wash water, the plant was well w i t h i n the BOD5 limit specified by the municipality.
4
b
SECTION IV PROCESS DESCRIPTION
This section describes a soybean extraction plant and refinery common t o Decatur and Lincoln. Additional corn germ extraction and refining in Decatur i s entirely analagous to the soybean process and w i l l n o t be described separately. Only those processes that generate significant waste products will be described i n detail. All processes operate 24 hours per day and 7 days per week, The plant in Decatur has the capacity for 120,000 bushels per day soybean extraction, and 200 tons per day of corn germ, and the capacity to refine 1 . 4 million lb per day of vegetable o i l . Figures 1 and 2 describe extraction and o i l refining respectively. SOYBEAN *PREPARATION AND EXTRACTION
The beans are i n i t i a l l y cleaned by mechanical screening. They are then cracked and cleaned by aspiration. This i s followed by heat conditioning in a steam tube drier. The cracks are flaked by flaking r o l l s and conveyed to an extractor, The o i l i s removed by continuous countercurrent hexane extraction. The f 1a kes a r e then conveyed t o the desol venti zer toaster where the v o l a t i l e solvent i s driven off by jacket and sparge steam. The vapors are condensed and the liquor pumped t o a gravity separator. The water insoluble hexane i s sent t o solvent storage and the water discharged to the sewer. The desolventized and toaster flakes a r e cooled, blended and loaded. The oil-hexane mixture i s pumped to d i s t i l l a t i o n where the solvent i s evaporated off and condensed. The o i l i s then pumped t o storage. The condensate water from t h i s process contains some entrained o i l and soluble protein b u t i s not a major source of BOD5 or f a t (See Section V ) . SOYBEAN OIL REFINING
The refining o f vegetable o i l may employ a combination of several processes, depending on the product desired. These processes include degumming, caustic refining, subsequent washing , vacuum drying , bleaching , hardening, p o s t bleaching, f i l t r a t i o n and deodorization. Degumming Approximately 2% water i s added t o the o i l to hydrate the gums (phosphatides). On hydration these gums become o i l insoluble and a r e separated from the o i l in a centrifuge. The gums are then dried t o produce lecithin. This step can be bypassed; however, i t decreases the amount of soapstock produced i n caustic refining and i n the case of soybean o i l , produces a Val uabl e by-product. 5
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Caustic R e f i n i n g Soybean o i l i s p r i m a r i l y t r i g l y c e r i d e w i t h approximately 0.5% t o 1 .O% f r e e f a t t y acids. The o b j e c t o f c a u s t i c r e f i n i n g i s t o c o n v e r t t h e f r e e f a t t y a c i d s t o water s o l u b l e soaps and then t o remove them by c e n t r i f u g a t i o n . A 12% sodium hydroxide water s o l u t i o n i s mixed w i t h t h e o i l . The water soap s o l u t i o n and o i l i s then separated i n a c e n t r i f u g e . The chemical equation f o r t h i s reaction i s :
0
+ NaOH
R-&
\OH The water soap s o l u t i o n ( c a l l e d soapstock) i s pumped t o a c i d u l a t i o n where s u l f u r i c a c i d i s added on a batch b a s i s t o c o n v e r t t h e soaps t o f a t t y acids. The f a t t y a c i d s a r e i n s o l u b l e i n water and f l o a t t o t h e surface. The m i n e r a l s a l t s and any water s o l u b l e m a t e r i a l remains i n t h e water l a y e r . The water l a y e r i s n e u t r a l i z e d and discharged t o t h e waste treatment f a c i l i t i e s . The chemical equation f o r t h i s r e a c t i o n i s :
+ H2S04
2 R-< -Na+ Water Wash
The o i l from c a u s t i c r e f i n i n g contains t r a c e amounts o f soaps and sodium hydroxide. Condensate water i s added t o t h e o i l and a g i t a t e d t o remove t h i s r e s i d u a l m a t e r i a l . The o i l and water from t h i s process i s a weak (1% t o 3%) soap s o l u t i o n w i t h a r e l a t i v e l y h i g h pH. Vacuum D r y i n g The o i l from water washing contains t r a c e amounts o f water t h a t can b l i n d t h e f i l t e r s i n subsequent f i l t r a t i o n operations. I n vacuum d r y i n g t h e o i l i s heated under a vacuum o f 28" Hg t o remove t h i s t r a c e moisture. There i s no s i g n i f i c a n t waste stream from t h i s process. B1eachi n g Trace amounts o f c o l o r bodies a r e removed by a b s o r p t i o n onto a c t i v a t e d bleaching c l a y . The c l a y and o i l a r e s l u r r i e d and heated under vacuum. The c l a y i s then removed i n pressure f i l t e r s and disposed o f i n t h e municipal landfill. Hardening Hardening i s employed t o r a i s e t h e m e l t i n g p o i n t o f t h e o i l f o r use i n s h o r t e n i n g o r margarine manufacture. T h i s i s done by t h e a d d i t i o n o f hydrogen to--unsaturated o i l molecules over a n i c k e l c a t a l y s t . The c a t a l y s t i s
8
blended with the oil and heated. The hydrogen gas is then bubbled through the mixture. The degree of hardening is determined by the temperature, pressure and quantity o f hydrogen gas added to the reaction. The catalyst is filtered out of the oil after the reaction is complete. No significant wastewater is generated by hydrogenation. Deodori za ti on The purpose o f deodorization is to remove volatile impurities that might cause flavors and odors. This is done by steam distillation at temperatures of 425°F to 475°F and 3 mm Hg absolute pressure. The high temperatures are obtained with a dowtherm boiler heating system. The vapors are pulled off through the vacuum system. (See Figure 3) A recycle deodorizer distillate scrubber remeves the bulk of the organic material from the vapor (99%+). Excess distillate is pumped to storage and sold as a valuable by-product. Deodorizer distillate is a valuable source o f a-tocopherol (Vitamin E). The remaining vapors, primarily steam, are condensed in the water scrubber along with any remaining organic material and drain to the greasy cool ing tower hot we1 1.
9
L
t
0
L 0
-3
0 Q) 0
10
~
I
SECTION V
WASTEWATER SOURCES, ANALYSIS, AND QUANTITIES
A l l analyses except COD were conducted according t o t h e t e s t procedures given i n Standard Methods = A n a l y s i s o f Water and Wastewater, 1 2 t h E d i t i o n . The t e s t procedure f o r COD i s given i n Appendix C. This m o d i f i e d procedure was used because o f t h e s h o r t e r r e f l u x time and because i t i s more c l o s e l y r e l a t e d t o BOD5 than t h e standard method. This m o d i f i e d COD w i l l be denoted by q u o t a t i o n marks. F i g u r e 4 compares t h e COD a n a l y s i s t o t h e BOD5 a n a l y s i s . Flows and wastewater a n a l y s i s f o r each wastewater source a r e presented i n F i g u r e 5. The condensate water i s generated i n h e a t i n g c o i l s and j a c k e t steam throughout t h e r e f i n e r y . I t i s g e n e r a l l y hot, c l e a n water and most o f i t i s being r e c y c l e d as washwater i n t h e r e f i n i n g step. Washwater generated i n t h e o i l washing step i s h i g h i n BOD and f a t p r i m a r i l y because of d i s s o l v e d soaps. The stream w i l l c o n t r i b u t e 1000 t o 5000 l b p e r day o f f a t o r BOD5 t o t h e sewer load. I f t h e o i l i s n o t degumned b e f o r e c a u s t i c r e f i n i n g , some water s o l u b l e phosphatides w i l l be removed i n t h i s step and w i l l cause higher loads. This i s g e n e r a l l y t h e case when corn o i l i s being processed. F l o o r washings a r e h i g h l y v a r i a b l e f o r obvious reasons. I t i s charact e r i z e d by h i g h temperature and h i g h pH because o f the washing equipment and soaps. Greasy c o o l i n g water can be a major source o f BOD5 depending on t h e o p e r a t i o n o f t h e deodorizer scrubber and atmospheric c o n d i t i o n s . (See d e o d o r i z a t i o n d e s c r i p t i o n Section I V ) Any organic m a t e r i a l t h a t passes through t h e scrubber becomes e m u l s i f i e d i n t h e greasy water i n t h e vacuum system. The greasy c o o l i n g tower d i s s i p a t e s t h e heat o f condensation o f t h e steam p r i m a r i l y by evaporation o f t h e greasy water. I n c o l d weather t h e water loses more heat by convection which decreases t h e amount o f evaporation necessary. When t h e amount o f water e n t e r i n g t h e tower v i a steam condensation i s g r e a t e r than t h e wind d r i f t p l u s evaporation, i t becomes necessary t o blow down t h e tower t o t h e sewer. The organic m a t e r i a l i n t h e water i s p r i m a r i l y s h o r t chain f r e e f a t t y acids. T y p i c a l COD values range up t o 3000 mg per l i t e r . For an o v e r f l o w o f 30,000 g a l p e r day, 750 l b o f COD would be discharged t o the sewer based on 3000 mg p e r l i t e r o f Pat.
11
5 -
I
--&&-
BOD5 = 35 + 1.01 "COD" 95% CONFIDENCE LIMITS
5000
4000
IC)
n 0
2000
1000
0 -
0
1000
2000 "
Figure 4.
3000
4000
COD" mg /I
BOD and COD correlation for total West plant effluent.
--
12
1
I
CONDENSATE WATER FL0W:O-100,000 GPD,. CONT. WASTEWATER CHARACTERISTICS: H1G.H TEMP ( APROX. 200' F); LOW BOD.
I I
I
1
I
I
L I
WASH WATER FLOW' 20,000-30,000 GPD, CONT WASTEWATER CHARACTER ISTlCS: HIGH TEMP. FREE AND EMULSIFIED OILS. BOD' 30,000 mg/l.
'I
1 1
FLOOR WASHING
I
I . GREASY COOUNG TOWER OVERFLOW I
FLOW: 0- 30,000 GPD W E WATE R CHARACT ERISTICS: TEMP 80~1OO0F, BOD 500-3000
500-3000mg/l.
pH 5-6
I
I
I S N K - C A R WASlilNG FI OW; 3,000- 10,000 GPD, INTERMITTENT DAY SHIFT ONLY WASTEWATER CHARACTERISTlCS: HIGH TEMP(APR0X. ISO'F); BOD ~00-60,000mg/l.
I I
' II I
I
I
I
+
ONLY. WASTEWATER CHARACTERISTICS: HIGH TEMP, VARIABLE BOD, FREE AND EMULSIFIED OILS.
I
I I
I I '
2
I I
II
FI OW;
10,000-30,000 GPD, INTERMITTENT WASTEWATER CHARACTE RlSTlCSl HIGH TEMP ( 1500-160°F) BOD 25,00030,060ma/l. FAT3006a)mg/l.~
r
EXTRACTION PLANT FLOW: 150,000 GPD, CONTINUOUS WASTEWATER CHARACTERISTICS: HIGH TEMP (APROX. 18OOF) LOW 800 (APROX. 200-500mg/l).
.-
I
I
13
Tank c a r washings vary from one t o f o u r cars per day. The e f f l u e n t i s characterized by h i g h temperature, 160"F, and a v a r i a b l e amount o f emuls i f i e d o i l . The BOD5 can be anywhere from 2000 t o 60,000 mg per l i t e r . (Table 1) The n e u t r a l i z e d a c i d u l a t i o n water f l o w and COD i s h i g h l y v a r i a b l e depending upon the amount o f f l u s h water being used on t h e c e n t r i f u g e s and whether o r n o t t h e o i l i s being degummed p r i o r t o t h e r e f i n i n g . The phosphatides which would be removed i n degumming g r e a t l y increase t h e s t r e n g t h o f t h e a c i d u l a t i o n water due t o t h e i r water s o l u b i l i t y . Fresh water can increase t h e moisture content of t h e soap from 50% t o 95%. While t h i s does n o t a f f e c t the t o t a l BOD5 load, i t does reduce t h e residence time i n treatment f a c i l i t i e s and reduces t h e processing time which i s necessary t o g e t good o i l separation. While t h e BOD5 i s very h i g h (25,000 mg per l i t e r ) f o r t h i s stream, t h e f a t i s r e l a t i v e l y low (300 - 500 mg per l i t e r ) . This i s t h e o n l y waste stream from the r e f i n e r y t h a t i s n o t composed p r i m a r i l y o f hexane s o l u b l e m a t e r i a l . A t y p i c a l day would y i e l d loadings o f 4000 l b p e r day BOD and 70 l b o f f a t based on 20,000 g a l a t a 25,000 mg per l i t e r BOD5 and 400 mg per l i t e r f a t . The e x t r a c t i o n p l a n t wastewater c o n s i s t s o f condensate described i n t h e process section. A t 150,000 g a l per day and 300 mg per l i t e r BOD, t h i s stream c o n t r i b u t e s o n l y 375 l b per day of BOD. The temperature i s h i g h (180°F) and t h e pH i s near n e u t r a l (6 - 8). Flows were estimated from process design requirements. (Table 2)
TABLE 1
.
CHARACTERISTICS OF REFINERY WASTEWATER COMPONENT STREAMS GRAB SAMPLES Sampl ing
Wastewater C h a r a c t e r i s t i c s pH Temp. ( O F )
Source
Date
T i me
Aci dul a t i on Tank
9-09-69
4 p.m.
26650
5.6
1150-1 60
Ac idul a t i on Tank
9-1 1-69
--
29220
4.6
150-1 60
Acidulation Tank ( S e t t l e d Sample)
9-1 1-69
9:30 a.m.
24760
5.0
150-1 60
Tank Car Washing (Crude Oil)
9-11-69
2 - 6 p.m. (Composite)
60400
6.0
150-1 60
Tank Car Washing (Hydrogenated)
9-11-69
(Composite)
4655
6.1
150-160
14
TABLE 1.
CHARACTERISTICS OF REFINERY WASTEWATER COMPONENT STREAMS GRAB SAMPLES (Continued) Sampl ing
Source Tank Car Wash ing (Hydrogenated)
Date
Time
9-16-69
(Composite)
TABLE 2.
Samp 1e Date
Wastewater C h a r a c t e r i s t i c s COD (mg/l) pH Temp. (OF)
2100
6.7
EXTRACTION PLANT LOADING
(ms/il)
Estimated Flow (GPD)
9-24-69
325
150,000
9-26-69
496
150,000
9-30-69
370
150,000
10-01 -69
360
150,000
10-02-69
370
150,000
Average
384
150,000
BOD
E x t r a c t i o n P1a n t
15
150-160
SECTION V I PRIMARY CHEMICAL TREATMENT The i n i t i a l o b j e c t i v e was t o determine by l a b o r a t o r y experimentation whether a chemical pretreatment o f any waste water stream was f e a s i b l e . Several chemicals, i n c l u d i n g polymers, p o l y e l e c t r o l y t e s , sodium c h l o r i d e and c a l c i u m c h l o r i d e were used. Calcium c h l o r i d e was found t o be t h e most economical and e f f i c i e n t coagulant a t dosages o f approximately 0.25% by weight. The equation f o r t h i s r e a c t i o n i s : 2 R-
