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The removal of heavy metals from municipal wastewaters by lime-magnesium coagulation MacLean, Byard H. 1977

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THE REMOVAL OF HEAVY METALS FROM M U N I C I P A L WASTEWATERS BY LIME-MAGNESIUM  COAGULATION  by  BYARD H. B.A.Sc,  MACLEAN  U n i v e r s i t y of B r i t i s h Columbia,  A Thesis  Submitted i n P a r t i a l  The R e q u i r e m e n t s f o r Master  F u l f i l l m e n t of  the Degree  of A p p l i e d  of  Science  in  The F a c u l t y o f G r a d u a t e Department of C i v i l  We a c c e p t t h i s  thesis  to the r e q u i r e d  Studies  Engineering  as  conforming  standard  THE U N I V E R S I T Y OF B R I T I S H COLUMBIA •' J u n e . 1977 @  B y a r d H. M a c L e a n ,  1971  1977  In presenting this thesis in partial  fulfilment o f the requirements f o r  an advanced degree at the University of B r i t i s h C o l u m b i a , I agree  that  the Library shall make it freely available for r e f e r e n c e and s t u d y . I further agree that permission for extensive copying o f t h i s  thesis  for scholarly purposes may be granted by the Head of my Department o r by his representatives.  It  is understood that copying o r p u b l i c a t i o n  o f this thesis for financial gain shall not be allowed without my written permission.  The University of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5  i  ABSTRACT  The e v i d e n c e o f h e a v y m e t a l b u i l d up i n t h e environment near  sewage t r e a t m e n t p l a n t o u t f a l l s a r o u n d  w i t h the g e n e r a l l y held theory that secondary i n t h i s area, leads that  is  treatment i s  not  required  t o t h e c o n c l u s i o n t h a t a t r e a t m e n t method i s  this  study,  required  j a r t e s t s were performed t o e v a l u a t e the  m e t a l removal e f f i c i e n c y of F i v e heavy m e t a l s  (Cr  3"j_  concentrations  combination. effluent  Vancouver,coupled  p r i m a r i l y aimed a t heavy m e t a l r e m o v a l . In  initial  aquatic  , Cu  of  the lime-magnesium c o a g u l a t i o n  heavy  process.  2*4* 2"f" 2H~ 21 , Pb , Ni a n d Zn ) were a l l t e s t e d at  . 5 , 2.5  and 5 . 0 mg/1  i n d i v i d u a l l y and  in  The e x p e r i m e n t s w e r e p e r f o r m e d o n p r e c h l o r i n a t e d p r i m a r y  a n d r a w sewage a t t h e n a t u r a l a l k a l i n i t y l e v e l s  ( 1 2 0 - 1 3 0 mg/1  C a C O - ) , and some w o r k was done a t e l e v a t e d a l k a l i n i t y ( 1 9 0 - 2 0 0 m g / 1 ) . The n e e d f o r f i l t r a t i o n Results  of  i n the process  the study  was a l s o  i n d i c a t e d t h a t the heavy m e t a l removal  e f f i c i e n c y was e n h a n c e d b y t h e p r e s e n c e o f Mg f o r a l l of  the heavy m e t a l s  researched.  except n i c k e l .  2+  at a g i v e n l i m e dosage  A comparison  indicated that 2+  i n t e r m e d i a t e l i m e t r e a t m e n t ( 2 2 0 mg/1)  c o u p l e d w i t h 33 mg/1 Mg  be a m o r e a t t r a c t i v e p r o c e s s  straight  (400  mg/1).  than j u s t  high  might  lime treatment  as  ii  TABLE OF  CONTENTS Page  1.  INTRODUCTION  1  2.  HISTORY OF THE HEAVY METAL PROBLEM  4  2.1  Toxicity  4  2.2  Heavy M e t a l C o n c e n t r a t i o n s i n the Urban Environment  6  2.3  Heavy M e t a l Removal P r o c e s s e s  8  2.3.1  Biological  8  2.3.2  Carbon A d s o r p t i o n  10  2.3.3  Lime C o a g u l a t i o n  12  3.  MAGNESIUM  4.  RESEARCH RATIONALE 4.1  4.2  5.  SOLUBILITY  H i s t o r y of the Lime-Magnesium Process Renovation  16  21 f o r Water  A p p l i c a t i o n of the Lime-Magnesium Process to Vancouver Watewaters  EXPERIMENTAL  METHODS AND MATERIALS  21  21  23  5.1  S e l e c t i o n of E f f l u e n t  23  5.2  Sampling Procedure  23  5.3  Sample S t o r a g e  23  5.4  Chemical Preparations  24  5.4.1  Heavy M e t a l S p i k e S o l u t i o n s  24  5.4.2  A.A.  24  5.4.3  Lime  5.4.4  Magnesium I o n  5.4.5  Sodium B i c a r b o n a t e  Standards  24 - 25 25  i i i  5.5  5.6 6.  A n a l y t i c a l Techniques  25  5.5.1  Alkalinity  25  5.5.2  Heavy Metal A n a l y s i s  25  5.5.3  pH  26  Lime-Magnesium Coagulation Test Procedure  26  RESULTS AND DISCUSSION 6.1  The Removal E f f i c i e n c y of I n d i v i d u a l Heavy Metals from Prechlorinated Primary Effluent (PPE) - U n f i l t e r e d Results  6.2  28  6.1.1  Chromium  28  6.1.2  Copper  32  6.1.3  Lead  36  6.1.4  Nickel  36  6.1.5  Zinc  36  6.1.6  Summary  43  The Removal E f f i c i e n c y of I n d i v i d u a l Heavy Metals from PPE - F i l t e r e d vs U n f i l t e r e d Results  6.3  The Removal E f f i c i e n c y of Mixed Metals from PPE F i l t e r e d vs U n f i l t e r e d Results  6.4  6.5 7.  48  48  The Removal E f f i c i e n c y of Mixed Metals from Raw Sewage - F i l t e r e d vs U n f i l t e r e d Results  56  The Effect of A l k a l i n i t y on Heavy Metal Removal  56  CONCLUSIONS  65 2+  7.1  The Effectiveness  of Mg  at various pH's  65  7.1.1  General  65  7.1.2  I n d i v i d u a l Metals i n PPE  65  7.1.3  Mixed Metals i n PPE  65  7.1.4  Mixed Metals i n Raw Sewage  65  iv  7.2  Residual Metals  i n the S e t t l e d Supernatant  7.3  The E f f e c t o f A l k a l i n i t y on H e a v y M e t a l R e m o v a l  65 66  2+ 7.4  The P o t e n t i a l o f Mg  for Full  Scale Treatment  66  BIBLIOGRAPHY  67  APPENDIX A - T e s t P r o c e d u r e Development  69  APPENDIX B - C o m p a r i s o n  81  vs  of High Lime Treatment (H.L.) 2+ 2+ I n t e r m e d i a t e Lime/Mg Treatment (I.L./Mg ).  1. CHAPTER  1  INTRODUCTION  T h e r e has been an i n c r e a s i n g c o n c e r n i n r e c e n t y e a r s problems  a s s o c i a t e d w i t h heavy m e t a l b u i l d - u p  aquatic environment. governments  levels  of  of the lower F r a s e r  f o u n d BOD v a l u e s > 90%  in  l e d most r e s e a r c h e r s  municipal wastewaters  t h e s e p r o b l e m s h a s moved many  River  standards.  system conducted by  Benedict  o f _< 1 mg/1 a n d 2 - 4 mg/1 a n d d i s s o l v e d  oxygen  is  This  information, coupled with r i v e r flow data,  to conclude that secondary  treatment of  Vancouver  not h i g h l y c o s t - e f f e c t i v e .  The p r e c i p i t a t i o n o f h e a v y m e t a l s b y l i m e c o a g u l a t i o n i s documented p r o c e s s involves This  a s COD,  (11).  SS  herein is  Cr  insitu  during  and c o l o u r to e s t a b l i s h  (8).  The m a i n o b j e c t i v e o f  lime  the research  The s p e c i f i c o b j e c t i v e s a r e a s  (Appendix  the  , Cu  2+  , Ni  2+  process  follows: lime-magnesium  A).  , Pb  2+  a n d Zn  2+ ) at various  p r e c h l o r i n a t e d p r i m a r y e f f l u e n t (PPE)  initial  (Section  (i.e.  concentrations  in  7.1).  i n the process  (Section  well  reported  To e v a l u a t e t h e r e m o v a l e f f i c i e n c y o f i n d i v i d u a l h e a v y m e t a l s 3+  process,  coagulation.  the heavy m e t a l removal e f f i c i e n c y of t h i s  To d e v e l o p a m e t h o d t o e v a l u a t e h e a v y m e t a l r e m o v a l b y  process 2)  ion  well  h a s b e e n shown t o be e f f e c t i v e f o r t h e r e m o v a l o f cadmium a s  f o r Vancouver m u n i c i p a l sewage. 1)  a  A s l i g h t m o d i f i c a t i o n , the lime-magnesium  the p r e c i p i t a t i o n o f magnesium  process  the  a n d > 80% o f s a t u r a t i o n f o r t h e M a i n Arm a n d N o r t h A r m /  M i d d l e Arm r e s p e c t i v e l y . has  the  from c u l t u r a l sources  to b r i n g i n s t r i c t e r p o l l u t i o n c o n t r o l  A study e t a l . (5)  The r e a l i z a t i o n o f  over  3)  To e v a l u a t e t h e n e e d f o r f i l t r a t i o n  7.2).  4)  To e v a l u a t e t h e r e m o v a l e f f i c i e n c y o f m i x e d m e t a l s i n PPE and  compare  these removals w i t h the i n d i v i d u a l metal data  (Section  7.3).  5) To c o m p a r e t h e r e m o v a l e f f i c i e n c y f r o m PPE t o t h a t f r o m r a w sewa; (Section 6)  7.4).  To e v a l u a t e t h e e f f e c t o f a l k a l i n i t y on t h e r e m o v a l e f f i c i e n c y  (Section  7.5). The e x p e r i m e n t a t i o n p r o g r a m i s  summarized  i n Table  1.  TABLE  1  EXPERIMENTATION PROGRAM Lead PPE  Copper PPE  Chromium PPE  Test Conditions  Nickel PPE  Zinc PPE  _ PPE  z RS  pH 1 0 . 0 Alk: natural  X  X  X  X  X  : x  X  pH 1 0 . 7 0 Alk: natural  X  X  X  X  X  X  X  pH 1 1 . 4 0 Alk: natural  X  X  X  X  X  X  X  pH 1 0 . 7 0 A l k : 1 8 0 - 2 0 0 mg/1 a s CaCO-  X  X  X  X  X  X  X  Notes:  1)  I n d i v i d u a l m e t a l runs were a l l performed s t a r t i n g w i t h t h e f o l l o w i n g i n i t i a l c o n c e n t r a t i o n s - .5 mg/1, 2.5 mg/1, 5.0 mg/1.  2) M g  2 +  dosage: 0, 8,  17,  33 and 50 mg/1.  3) PPE - p r e c h l o r i n a t e d p r i m a r y 4)  RS -  raw  effluent.  sewage.  5) N a t u r a l a l k a l i n i t y : 1 2 0 - 1 3 0 mg/1 6)  metal  as  CaCO-.  E i n d i c a t e s a combination of a l l f i v e m e t a l s each w i t h i n i t i a l .5 mg/1.  concentration  of  4. CHAPTER 2 HISTORY OF THE HEAVY METAL PROBLEM 2.1 T o x i c i t y The major areas of concern w i t h respect to the heavy metal problem i n the aquatic environment i s that of t o x i c i t y to b i o l o g i c a l organisms at low concentrations.  The b u i l d - u p of heavy metals i n Vancouver s t r e e t  sediments and i n the r i v e r sediments near Vancouver sewage treatment plant o u t f a l l s has become an area of i n c r e a s i n g concern ( 4 , 5 , 1 2 , 1 3 ) . The factors that contribute to the problem of t o x i c i t y of heavy metals are as f o l l o w s : 1) being elements, heavy metals do not degrade and hence tend to b u i l d up i n the environment (stream sediments). 2) some heavy metals are susceptible to food chain concentration. 3) most heavy metals are t o x i c to l i v i n g organisms i n f a i r l y low concentrations. The t o x i c i t i e s of the f i v e heavy metals used i n t h i s study (Cr,  Cu, Pb, N i , Zn) are summarized i n the following paragraphs. a) Chromium.  The USPHS Drinking Water Standard (19) for hexavalent  chromium i s .05 mg/1, although i t does not appear to have any, p h y s i o l o g i c a l effects on humans and i s not retained i n the body.  S i m i l a r l y , hexavalant  and t r i v a l e n t chromium have no s i g n i f i c a n t effect on animals at dosages of the order of 25 mg/1 (19).  F i s h are r e l a t i v e l y t o l e r a n t of chromium s a l t s , but  lower forms of aquatic l i f e are extremely s e n s i t i v e .  McKee and Wolf (19)  conclude that concentrations above 1.0 mg/1 for f i s h and .05 mg/1 for other aquatic l i f e w i l l have t o x i c e f f e c t s .  The concentration of r a d i o a c t i v e chromium  by algae has been found to be i n the range of 100 to 500 times (19) that present i n the water.  5.  b) poisoning copper  Copper.  among human b e i n g s h a s  industries  colored green". this  is  McKee a n d W o l f  range of  state  enough copper  The USPHS D r i n k i n g  Water  indicates  through  .1 mg/1  a r e a of  of  copper  toxicity  t o be w i t h t h e l o w e r b i o l o g i c a l f o r m s .  to a q u a t i c organisms v a r i e s  that  .05 mg/1  copper  f r e s h w a t e r and  concentrations.  factors  of  1000  to  Lead i s  human b e i n g s o r o t h e r  not  animals  considered  and i s  Water  authorities  agree  is  t h a t v5 mg/1  for animals.  to f i s h l i f e  T h e USPHS h a s  not a great  caused  to  in  copper of  and w i t h (19)  phys-  indicate  beneficial  c o n c e n t r a t e copper  Standard  as  poison  has  by  l o w as  not  set  a drinking  (19).  water  Nickel is  Concentrations  toxic  (19).  Due  to  .05 mg/1.  as  Most  lead i n a potable.,  .1 mg/1 h a v e  been  (19).  standard  n i c k e l appears  for  of  s o u r c e s as w e l l  been set a t limit  i n soft water  to both.  believed  to be  for nickel.  t o f i s h and o t h e r a q u a t i c  of n i c k e l s a l t s  i n t h e 10-15  very  Although  t o be q u i t e i n j u r i o u s  a 50 p e r c e n t r e d u c t i o n i n t h e b a e g e r i a l i o x y g e n c u t i l i z a t i o n  synthetic-sewage  and  on a w i d e  to the n u t r i t i o n  The t o x i c i t y o f n i c k e l t o man i s  d e a l of d a t a e x i s t s ,  mg/1  mg/1  be  beneficial  and Wolf  f o o d and a i r  a maximum s a f e  especially  even at low c o n c e n t r a t i o n s . about.1.0  to  The t o x i c i t y  sea water are  essential  through  Lead c o n c e n t r a t i o n s  d) N i c k e l . low.  for  McKee  a cummulative  l e a d may e n t e r . t h e b o d y  t h e USPHS D r i n k i n g  deleterious  the water.  indicate that plankton  from water,  supply  is  in  5000.  c) Lead.  the f a c t that  Studies  studies  s i g n i f i c a n t l y with species of  for  1.0  concern w i t h respect  i c a l and c h e m i c a l c h a r a c t e r i s t i c s .02 mg/1  their skin  Toxicological  (19).  copper  copper  e v e n among p e o p l e  i r r i g a t i o n water appears  The m a j o r  that  "Chronic  S t a n d a r d s recommend  taste considerations.  commercial crops  that  never been proved,  who h a v e a b s o r b e d  primarily for  (19)  mg/1 from  to  plants  life range  at  6. e) animals,  Zinc.  Z i n c h a s no known p h y s i o l o g i c a l e f f e c t s u p o n man o r  except at high  c o n c e n t r a t i o n s , a n d t h e USPHS D r i n k i n g W a t e r  Standard  o f 5 mg/1 was s e t due m a i n l y t o t a s t e t h r e s h o l d c o n s i d e r a t i o n s .  It  toward f i s h and a q u a t i c organisms  lacking  calcium hardness,  exhibits its  concentrations of  z i n c f r o m 0.1  appears toxic  to have s y n e r g i s t i c  that z i n c , e s p e c i a l l y i n water  greatest t o 1.0  t o x i c i t y (19) .  In  zinc.  100,000  From t h e above d i s c u s s i o n  c o n c l u s i o n can be drawn -  i n a l l p r o b a b i l i t y , one o f s y n e r g i s m  The u s e s o f  Centre survey  determined i n samples  i n measureable In  Seattle  is  shown s e p a r a t e l y  to Vancouver.  since  street surfaces.  coast  As w o u l d b e e x p e c t e d , t h e h i g h e s t  also  amounts  is  in  the  a Westwater  data for  shown i n T a b l e 2.  t h i s west  i n t h e i n d u s t r i a l and c o m m e r c i a l a r e a s  e t a l . (13)  and i t  the c o n c e n t r a t i o n s of eleven t r a c e metals  The d a t a i s  the  antagonism.  s t u d i e d a r e numerous  c o l l e c t e d from Vancouver  i n the United S t a t e s .  e f f e c t on  Environment  from the c i t y of Vancouver.  (13)  to  the o v e r a l l e f f e c t  compared t o E n v i r o n m e n t a l P r o t e c t i o n Agency' ( E . P . A . )  cities  of  i n the Urban  that they are present  combined sewer d i s c h a r g e s Research  r a t h e r than  the f i v e heavy m e t a l s  therefore not s u r p r i s i n g  quite  o f h e a v y m e t a l t o x i c i t y one m a j o r  a l l f i v e m e t a l s e x h i b i t an i n j u r i o u s  2.2 Heavy M e t a l C o n c e n t r a t i o n s  Copper  (19).  a q u a t i c e n v i r o n m e n t and i n c o m b i n a t i o n w i t h one a n o t h e r  is  Zinc i s  t o s h e l l f i s h a n d i t h a s b e e n shown t h a t t h e y h a v e b e e n a b l e  '  was  water,  mg/1 h a v e b e e n r e p o r t e d t o x i c .  e f f e c t on t h e t o x i c i t y o f  c o n c e n t r a t e Zn-65 by a f a c t o r o f  is,  soft  is  c i t y has  This  were data  several  The d a t a  for  a similar climate  degree of m e t a l c o n t a m i n a t i o n  for a l l three sets  of data.  Hall  c o n c l u d e d t h a t l e a d c o n t a m i n a t i o n was n o t o n l y a f u n c t i o n  l a n d use b u t a l s o  of  traffic  A s t u d y by Tanner  volume.  e t a l . (25)  on t h e c h a r a c t e r i s t i c s o f  Vancouver  Table 2:  Average Trace Metal Concentrations i n Street Surface Contaminants from 8 U.S. C i t i e s (from H a l l et a l .  Study Area  Land Use  (13))  Number of Stations  Ag  Cd  Co  Cr  Cu  87  208  780  18,200  Fe  Ni  Mn  62  44  220  1,243  296  Hg  b  Pb  Zn  Vancouver, B.C.  Industrial  8  0.6  1.5  (Brunette River Basin)  Commercial  6  0.7  2.4  9 5  141'  212  20,400  117  34  232  1,415  702  Residential  8  0.5  1.2  6 3  140  133  18,500  40  46  195  710  404  Green Space  4•  0.3  1.2  8 9  144  117  16,850  22  27  226  100  246  32. 2  163  347 .  18,590  62  35  216  867  415  20  490  1,100  480  -  Overall  Seattle, Washington  United S t a t e s (8 c i t i e s )  '  26  0.5  1.6  Industrial  1  -  1.4  239  110  27,000  Commercial  2  1.9  206  136  37,000  -  40.  435  4,000  445  Residential  4  Overall  1.6  244  76  36,500  -  37  455  2,450  497  7  -  1.5  247  97  35,000  -  35 •  454  2,700  480  Industrial  38  -  4.1  279  120  28,000  37  590  1,600  360  Commercial  19  5.1  226  170  24,000  -  52  400  3,600  520  Residential  22  189  91  21,000  -  26  370  1,600  380  Overall  79  209  120  24,000  -  34  440  2,000  400  0  b  3.1 3.8  -  concentrations as mg/kg dry weight of sediment „ Hg concentrations as ug/kg dry weight of sediment  c  P i t t and Amy  (1973)  8. wastewaters  c o n c l u d e d t h a t the m a j o r i t y o f the sewers c o n t a i n s u f f i c i e n t  contaminants  to be t o x i c to f i s h .  o r g a n i c contaminant  The r e s e a r c h e r s measured heavy m e t a l and  c o n c e n t r a t i o n s and i n d i r e c t l y c o n c l u d e d t h a t the heavy  m e t a l s were p a r t i a l l y r e s p o n s i b l e f o r the  toxicity.  Due to the t o x i c e f f e c t o f heavy m e t a l s on t h e a q u a t i c an a r e a o f prime c o n c e r n has been the b u i l d - u p o f heavy m e t a l i n the F r a s e r R i v e r s e d i m e n t s , ment p l a n t s .  environment,  concentrations  e s p e c i a l l y a t the o u t f a l l s o f sewage  A comparison o f the heavy m e t a l c o n c e n t r a t i o n s  o f the Iona I s l a n d sewage treatment p l a n t to c o n c e n t r a t i o n s  i n the  treatsediments  at four other  locations  i s p r e s e n t e d i n T a b l e 3. There i s no b u i l d - u p of heavy m e t a l s a t t h e L u l u I s l a n d sewage t r e a t m e n t p l a n t o u t f a l l due to the h i g h v e l o c i t y o f t h e r i v e r a t t h i s p o i n t and a l s o due to the f a c t t h a t the p l a n t has o n l y been o p e r a t i o n a l for three years.  Around the Iona I s l a n d sewage t r e a t m e n t p l a n t o u t f a l l t h e r e  appears t o be i n c r e a s e s  i n heavy m e t a l c o n c e n t r a t i o n s  i n the sediments  1.25 t o 20 t i m e s the n a t u r a l background c o n c e n t r a t i o n s .  from  G r i e v e and F l e t c h e r  (12) i n a s t u d y concerned w i t h heavy m e t a l c o n c e n t r a t i o n s as a f u n c t i o n o f sediment g r a i n s i z e on the F r a s e r R i v e r D e l t a a l s o found i n c r e a s e s l e a d and z i n c a t the o u t f a l l o f the Iona I s l a n d Sewage Treatment  i n copper,  Plant.  2 . 3 Heavy M e t a l Removal P r o c e s s e s A t the p r e s e n t time t h e r e are a number o f d i f f e r e n t heavy m e t a l removal p r o c e s s e s i)  The t h r e e most f a m i l i a r p r o c e s s e s  removal d u r i n g b i o l o g i c a l  ii)  treatment  carbon a d s o r p t i o n  iii)  lime coagulation.  2.3.1 Biological It  being researched.  Treatment  i s g e n e r a l l y f e l t t h a t the removal of heavy m e t a l s d u r i n g  b i o l o g i c a l t r e a t m e n t can proceed by e i t h e r o f t h r e e mechanisms:  are:  TABLE 3 A comparison o f t h e heavy m e t a l c o n c e n t r a t i o n s i n t h e I o n a Dyke sediments t o those i n f o u r o t h e r l o c a t i o n s around Vancouver.  C iiGhriomium  Location  Copper  Lead  Nickel  Zinc 170  200  183  55  157  Lulu Is^S.T.P. Outfall"  18  21  34  4  25  (3)  Roberts  Bank  -  274  39  4  60  (4)  Woodward I s . ( M a i n Arm)  -  39  62  6  50  N o r t h Arm o f Fraser River  -  34  40  16  72  Average of 2,3,4,5  18  30  44  8  52  llx  6x  1.25x  20x  3.25x  (1)  Iona  (2)  (5)  (6)  Dyke  I n c r e a s e i n I o n a Dyke Concentrations over 6  Concentrations  i n mg/Kg  of  sediments.  High v e l o c i t y of r i v e r at this point does not allow sedimentation.  10. i)  P r e c i p i t a t i o n of metal hydroxides  entrapment i n the b i o l o g i c a l ii)  or carbonates w i t h  floe.  Some f o r m o f s o r p t i o n b y t h e o r g a n i c  iii)  subsequent  Biological cell  solids.  uptake.  The r e m o v a l e f f i c i e n c y f o r h e a v y m e t a l s b y b i o l o g i c a l w a s t e ment h a s b e e n s t u d i e d b y s e v e r a l r e s e a r c h e r s is  p r e s e n t e d i n T a b l e 4.  unpredictable.  This  treatment p l a n t s  is  The r e m o v a l e f f i c i e n c y a p p e a r s  of  their  to be  s t u d i e d by B a r t h e t a l . (7)  somewhat  o v e r a 14 d a y s a m p l i n g  16-73%,  chromium, c o p p e r , n i c k e l and z i n c B a r t h e t a l . (6)  8-78%  and 53-85%  plant  studies  period.  for  respectively.  s t u d i e d the e f f e c t s of c o p p e r , chromium, n i c k e l  and z i n c , i n d i v i d u a l l y and i n c o m b i n a t i o n , on a c t i v a t e d s l u d g e Pilot  results  b e s t shown b y c o m p a r i n g t h e t h r e e d i f f e r e n t s e w a g e  T h e y f o u n d r e m o v a l r a n g e s o f 37 t o 8 2 % , hexavalent  a n d a summary  treat-  treatment.  i n d i c a t e d t h a t a t o t a l heavy m e t a l c o n c e n t r a t i o n of  10 mg/1 e i t h e r s i n g l y  or i n combination, would reduce the o v e r a l l p l a n t  e f f i c i e n c y b y a b o u t 5%.  T h e y f u r t h e r c o n c l u d e d t h a t n i t r i f i c a t i o n was  i n h i b i t e d b y h e a v y m e t a l s a n d t h a t t h e r e was no a c c l i m a t i o n o f  the n i t r i f y i n g  organisms to the m e t a l s . From t h e p r e v i o u s  discussion  two c o n c l u s i o n s  can be drawn  concerning  heavy m e t a l removal d u r i n g b i o l o g i c a l t r e a t m e n t . i) be designed  The r e m o v a l e f f i c i e n c y i s i n t o the  ii)  u n p r e d i c t a b l e and t h e r e f o r e  cannot  system.  High m e t a l c o n c e n t r a t i o n s appear  to  have adverse  e f f e c t s on  the  treatment e f f i c i e n c y .  2.3.2  Carbon  Adsorption  C a r b o n a d s o r p t i o n has b e e n u s e d as a p o l i s h i n g refractory organics remove.  In  the past  step  t o remove  that conventional b i o l o g i c a l treatment processes few y e a r s  r e s e a r c h has been c a r r i e d out  to apply  the  fail this  to  TABLE  4  Heavy M e t a l Removal  during  B i o l o g i c a l Waste T r e a t m e n t 1  •  -  - •  % Remo v a l Cr  Cu  50-70 . 5ppm*  -  Researcher Jenkin et a l .  (2)  McDermott e t a l .  Moore'et  Barth  al.  -:•  (2)  (7)  -  60-80 10-l60ppm* 95-74 2.5-20ppm*  30  50-79 .4-25ppm*  >99 .05ppm*  (2)  Zn  Ni  -  -  —  a)  40  16  12  58  b)  82  73  78  85  c)  37  23  8  53  d)  80 t  a)  Grand R a p i d s , M i c h i g a n  b)  Richmond, I n d i a n a  c)  Rockford, I l l i n o i s  d)  Bryon, Ohio  ^initial  14 d a y  14 d a y 13 d a y  (50 l b . s l u g  c o n c e n t r a t i o n range  sample  sample sample dose)  12.  process  to heavy m e t a l r e m o v a l . Westvaco  carbon process Although salts  (22)  r e p o r t e d m e r c u r y l e v e l s < 50 ppb when a n a c t i v a t e d  was a p p l i e d t o . a . c a u s t i c w a s t e s t r e a m f r o m a p u l p  the mercury.was  and o r g a n i c  forms)  present  i n s e v e r a l forms  t h e r e m o v a l was  cluded that carbon adsorption.might.be trace metals for i)  the f o l l o w i n g  Carbon i s  still  mill.  (metallic droplets,  quite high.  Smith  inorgan  (22)  a t t r a c t i v e f o r the removal of  con-  other  reasons:  an e f f e c t i v e r e m o v a l agent  even a t v e r y  low  solution  concentrations; ii) carbon.has  The r e m o v a l a c t i o n i s  a capacity f o r the metal i n several d i f f e r e n t iii)  C a r b o n c a n b e r e g e n e r a t e d and  Linstedt obtained removals  et a l . of  (8)  97.1%,  forms.  plant  9 8 . 8 % , 96.96%?arid'4" 3,.?2%:for s i l v e r , The mechanism of  this  than the a d s o r p t i o n of  the m e t a l s as i n o r g a n i c  inorganic  removal  compounds  ions.  The O r a n g e C o u n t y W a t e r D i s t r i c t o p e r a t e d a p i l o t of  studies  cadmium,  <  s p e c u l a t e d t o be c a u s e d by t h e a d s o r p t i o n o f m e t a l o r g a n i c  rather  the  reused.  i n carbon adsorption p i l o t  chromium and s e l e n i u m r e s p e c t i v e l y . was  r e l a t i v e l y non-specific, that i s ,  plant  consisting  l i m e c o a g u l a t i o n , ammonia s t r i p p i n g a n d a c t i v a t e d c a r b o n a d s o r p t i o n  remove heavy m e t a l s f r o m s e c o n d a r y obtained average  removals  of  treated e f f l u e n t (3).  The p i l o t  9 5 % , ? ' 7 0 % ? C 3 0 % d a n d : 7 8 % _ f o r hexava-lent.;.--  to  plant -  chromium, c o p p e r , l e a d and z i n c r e s p e c t i v e l y . It pilot  plant  s h o u l d be n o t e d t h a t i n b o t h o f studies  the p r e v i o u s l y  c a r b o n a d s o r p t i o n was u s e d a s a p o l i s h i n g  g r o s s m e t a l r e m o v a l was p e r f o r m e d b y c o a g u l a t i o n and 2.3.3  Lime  mentioned step a f t e r  filtration.  Coagulation The p r e c i p i t a t i o n o f m e t a l h y d r o x i d e s  is  dependent upon the  the  13.  c o n c e n t r a t i o n o f t h e m e t a l i o n i n s o l u t i o n a n d t h e pH o f following  the s o l u t i o n .  The  e q u a t i o n i n d i c a t e s the interdependancy of pH, m e t a l c o n c e n t r a t i o n  and m e t a l s o l u b i l i t y ; a s pH i n c r e a s e s  the s o l u b i l i t y of  the metal  hydroxide  decreases.  r  M  +  n  i roH~i  n =  [M(OH) J  sp  n  T a b l e 5, t a k e n f r o m B r o u z e s some h e a v y m e t a l o x i d e s  or h y d r o x i d e s .  (10),  lists  t h e s o l u b i l i t y products of  T h e o r e t i c a l l y , of  the metals  studied,  3+ Cr  s h o u l d y i e l d t h e b e s t r e m o v a l when p r e c i p i t a t e d w i t h l i m e a l o n e and 2+  removals  o f Cu  2+ , Pb  2+ and Zn  S e c t i o n 7 t h i s was t h e  the  s h o u l d be a b o u t  t h e same.  As w i l l  be seen  case.  T a b l e 6, r e p r o d u c e d f r o m A r g o a n d C u l p  (11)  gives  the r e s u l t s  of  l i m e c o a g u l a t i o n t r e a t m e n t o f a number o f d i f f e r e n t t y p e s o f m u n i c i p a l and domestic wastes.  It  lime coagulation - i s  appears  that for  the m a j o r i t y of  reasonably e f f e c t i v e .  the metals  tested  in  TABLE Solubility  5  P r o d u c t s of C a t i o n i c  M e t a l Oxides or  Heavy  Hydroxides  Compound  Ksp  SnO  1 x  Au(OH)Ti(OH)  8.5  x  10  - 6 1  10  - 4 5  1 x  lO"  Fe(OH).  6 x  10  Cr(OH)-  1 x  10  HgO  3 x  10"  3 x  10  3  Cu(OH).  4 0  - 3 8  2 6  -19  Zn  4.5 x  10~  Fe(OH)-  1.8  x  10  - 1 5  1.6  x  10  - 1 5  2 x  10  - 1 4  Pb-0(OH) Cd(OH) Mn(OH)  2  2  2 x 10  -13 J  BiOOH  3 x  10  BaSO. 4  1 x  lO"  BaC0 Ag 0 2  3  1.6  x  2 x  1 7  - 1 1  10~ 10  1  9  - 8  0  15. TABLE 6:  LIME COAGULATION AND RECARBONATION  Concentration Before Treatment mg/1  Metal  Concentration A f t e r Treatment mg/1  Antimony''" Arsenic Barium  1  1  M..3(sol)  Bismuth  1  .  Trace  11  .90  11  <10  11 11  0.00075  >11  94.5  >11  11  (+6)  0.056  0.050  Chromium  (+3)  7.400  2.7  •8.7  0.79  8.7  15.700 7  Gold  1  8  86  0.05  9.5  93  302  Trace  9.1  99+  <.001(sol) 13  2.4  17  0.1  2.0 Lead  1  Manganese  11 9.1  1.2  3  10.8  99+  10.5  40  <.0001(sol)  11  90+  <0.1  10.8  96  2.0  l.l  10.5  45  9.5  95  1  3  0.05 Oxide s o l u b l e  Molybdenum  Trace  Nickel  90+ 82  2.3  21.0 Mercury  99.9+  7  1  Iron  -v50  0.0137 Chromium  Copper  Percent Removal  11  2  0.0002(sol)  Cadmium  Final pH  <10 8.2  M0  160  0.08  8.7  99.9+  5  0.5  8  90  5  0.5  9.5  90  100  1.5  10.0  Selenium  0.0123  0.0103  >H  Silver  0.0546  0.0164  >11  1 Telurium Titanium  1  4 4  Uranium"*  , 97  (<0.001?)  11  (?90+)  (<0.001?)  11  (?90+)  ?  Zinc  99 16.2  ? .007(sol)  11  90+  1.  The p o t e n t i a l removal of these metals was estimated from s o l u b i l i t y data.  2.  Barium and lead r e d u c t i o n s and s o l u b i l i t i e s are based upon the carbonate.  3.  These data were from experiments using i r o n and manganese i n the organic form.  4.  Titanium and Telurium s o l u b i l i t y and s t a b i l i t y data made the p o t e n t i a l r e d u c t i o n estimates unsure.  5.  Uranium forms complexes w i t h carbonate i o n .  Q u a n t i t a t i v e data were  u n a v a i l a b l e to allow determination of t h i s e f f e c t . 6.  Temperature:  Ambient 20-25°C.  16.  CHAPTER 3 MAGNESIUM S O L U B I L I T Y Stumm a n d M o r g a n ( 2 1 ) points  o f v i e w : 1)  a system which i s  i n e q u i l i b r i u m w i t h CO-(g). (they considered only H.CO-  was  s t u d i e d t h e s y s t e m o f M g - C O . - H - O f r o m two  t r e a t e d as  2)  open t o t h e atmosphere  a system which i s  and i s  closed to the  t h e s o l i d phase and t h e s o l u t i o n p h a s e ,  therefore  atmosphere  that  is,  a non-volatile acid). 2+  A predominant i n Figure  diagram f o r log(Mg  1 f o r the open Mg-CO.-H-O s y s t e m .  corresponding specie over  t o t h a t of the atmosphere  to  (Mg^CO^) ^(OH) 3H 0(s) ) i f 2  2  ) = 0 and - 3  is  presented  At a p a r t i a l pressure  (log P  the e n t i r e c o a g u l a t i o n range  hydromagnesite respect  species  _  of 10.0  = -3.5)  the  of  CG^  predominant  t o 11.4 would be  t h e s y s t e m was a t e q u i l i b r i u m w i t h  C0 . 2  2+ A s o l u b i l i t y diagram system i s soluble  shown i n F i g u r e  2.  (-log(Mg In  this  ) vs  pH)  f o r the closed  case b r u c i t e (Mg(OH) ) 2  s p e c i e under  p r o b a b l y Mg(OH)^ f o r t h e f o l l o w i n g 1)  Mg^(CO ) (OH) .3H 0) 3  -2 The CO^ there i s  3  source  usually  2  is  least  2  and c a r b o n a t e s  of m u l t i v a l e n t  g e n e r a l l y l i m i t e d to the i n i t i a l  that the r e a c t i o n r a t e f o r Mg(0H)  O t h e r magnesium  carbonates  2  2  will  forms w i l l  is  most  b e u s e d up i n i t i a l l y  i n s u f f i c i e n t time to convert C0 (g)  test r e a c t i o n time, Mg(0H) ide.  2  reasons:  The a l k a l i n i t y i n t h e w a s t e w a t e r w i l l  hydromagnesite  Assuming  the  the c o a g u l a t i o n c o n d i t i o n s  p r e c i p i t a t e l i m e a s CaCO^ a n d t o p r e c i p i t a t e h y d r o x i d e  because  2  a b o v e pH 9 . The p r e d o m i n a n t  present.  is  Mg-C0 ~H 0  2  is  not slower  (e.g. cations  alkalinity -2 t o CO^ .  than the  p r e d o m i n a t e due t o t h e a b u n d a n c e be p r e s e n t b u t i n l e s s e r  to  amounts.  jar of  hydrox-  17.  FIGURE I PREDOMINANCE DIAGRAM FOR Log(Mg 0 A N D - 3 (STUMM AND  )=  M O R G A N , 1 9 7 0 ).  1- M g C 0 - 3 H 0 3  -2H  2  2- Mg (C0 ) JOH)2-3H 0 4  3  3"Mg(0H)  3  2  2  -4H  o  '  1  5  1  7  1  1  9  II  PH  1  13  ^  FIGURE 2 SOLUBILITY DIAGRAM. R§jR MAGNESIUM IN WATER AT ATMOSPHERIC CONDITIONSTOTAL G E M M A T E = IO' M. 3  (STUMM AND. MORGAN , 1970)  19.  2) (e.g.  S  The a f f i n i t y o f n a t u r a l a q u a t i c l i g a n d s  and P O ^ ) 3  might  f o r m more s t a b l e f o r m s  p r e c i p i t a t i o n pH t h e s e o t h e r s p e c i e s concentrations  t h a n OH  Larson and N o u v e l  (27)  o f magnesium  as  will  (16)  usually  be p r e s e n t  used s o l u b i l i t y product  t o show t h e i n f l u e n c e o f shown i n F i g u r e  3.  would be i n c r e a s e d w i t h i n c r e a s i n g  That  i n Figure is  to say  CO^  2  the  i n much  lower  predominate.  constants  From t h e work of L a n g l i e r  alkalinity.  At  and  of  Travers  t e m p e r a t u r e a n d pH o n t h e  that the s o l u b i l i t y curves  slightly with increasing  t h a n OH  than MgCOH^.  and t h e r e f o r e t h e M g C O H ^ w i l l  et a l .  been e s t a b l i s h e d  other  solubility  (15)  it  3 w o u l d move  up  that the  has  solubility  alkalinity. 2+  I n p r a c t i c e , t h e amount set of  conditions  1) T h e s y s t e m i s  This not at  The f o r m a t i o n o f  comes a b o u t  s o l u b l e hydroxo  the o v e r a l l . m e t a l s o l u b i l i t y .  expressed  by the f o l l o w i n g e q u a t i o n : M = [M ] + E [M(OH) ] t 2 n 2 +  (ML ) ^ P P Z  s o l u t i o n under a  several  higher  than  reasons.  complexes  (e.g.  The m e t a l s o l u b i l i t y  MgOH ) +  (M ) £  will  c a n be  Z _ n  The p r e s e n c e which w i l l  for  is  given  equilibrium.  increase  3)  in.aqueous  ( i . e . p H , t e m p e r a t u r e , a l k a l i n i t y , TDS)  that p r e d i c t e d from theory.  2)  o f Mg  of  foreign ligands  further increase  (L ^)  the metal  will  form s o l u b l e  solubility.  complexes  MAGNESIUM  S O L U B I L I T Y ( a s p a r t s p e r million C a C 0 ) 3  B A S E D ON T H E S O L U B I L I T Y OF T R A V E R S AND pH V A R I A T I O N H  +  PRODUCT CONSTANTS  NOUVEL.( 1929)  WITH  TEMP. DUE TO C H A N G E S  ACTIVITY  F I G U R E 3 T E M P E R A T U R E I N F L U E N C E ON MAGNESIUM SOLUBILITY. (LARSON  ET  A L , 1959)  ( 16)  IN  21.  CHAPTER 4 RESEARCH RATIONALE 4.1  History  of  the Lime-Magnesium  The u s e o f m a g n e s i u m e s t a b l i s h e d as colloidal  a successful  and suspended  l i m e , w o u l d remove o r g a n i c (8)  Renovation  i o n , p r e c i p i t a t e d i n s i t u as M g C O H ) ^ has  coagulant  for  the removal of  (26)  demonstrated  Thompson ( 9 )  l i m e a n d MgCO^ a s  r e l e a s e d i n any s i g n i f i c a n t R u s h (21)  amounts  showed  They  g r e a t l y enhanced by  also  found  on c a r b o n a t i o n  removal mechanism i s  It and suspended to high  secondary solids In  probably  not  to r e s o l u b l i z e the magnes-  effluents  and  low  than  3-5  a gelatinous  n a t u r e and  the  some c o m b i n a t i o n o f a d s o r p t i o n , p r e c i p i t a t i o n , entrapment.  the lime-magnesium  process  to Vancouver  b e e n f a i r l y w e l l d o c u m e n t e d by H a l l e t a l .  solids  dissolved  and  using  t h a t a c o m b i n a t i o n o f low magnesium  p r e c i p i t a t e has  2  f l o c c u l a t i o n and  has  Black  alone.  The h y d r a t e d M g ( O H )  4.2 A p p l i c a t i o n of  solids  t h a t cadmium was  lime could achieve a b e t t e r d e c o l o u r i z a t i o n of K r a f t m i l l  complexation,  Black  suspended  compared w i t h l i m e a l o n e .  showed t h a t c a d m i u m r e m o v a l was  t i m e s a s much l i m e  dissolved,  c o l o u r and t u r b i d i t y f r o m n a t u r a l w a t e r s .  in conjunction with lime.  i u m a s MgCO^.  been  t h a t MgCO^, p r e c i p i t a t e d w i t h  f o u n d a n i n c r e a s e d r e m o v a l e f f i c i e n c y f o r COD,  and c o l o u r when u s i n g  magnesium  f o r Water  material.  Thompson e t a l .  et a l .  Process  i n Vancouver's  oxygen l e v e l s  is  (15)  that  BOD  s e w a g e a r e n o t o f p r i m e c o n c e r n due  i n the F r a s e r  treatment of wastewater  wastewaters  designed  River.  As was p r e v i o u s l y  p r i m a r i l y f o r BOD a n d  primarily discussed,  suspended  r e m o v a l , w i t h the u n p r e d i c t a b l e s i d e b e n e f i t of heavy m e t a l r e m o v a l .  the Vancouver  a r e a a more p r a c t i c a l p r o c e s s  m i g h t b e one a i m e d a t p r e d i c t a b l e  h e a v y m e t a l r e m o v a l , w i t h t h e s i d e b e n e f i t o f BOD a n d s u s p e n d e d  solids  removal.  22.  I t was  felt  t h a t r e s e a r c h was w a r r a n t e d t o s e e i f  could achieve t h i s  c o a g u l a t i o n because (<  there is  5, mg/1  process  end.  A l i m e - m a g n e s i u m c o a g u l a t i o n was  waters  a c o a g u l a t i o n type  of  (5)  chosen over j u s t a s t r a i g h t  t h e low n a t u r a l magnesium  ).  already a source  In  levels  i n the  a r e a s where t h e n a t u r a l magnesium  o f Mg  2+  lime  surrounding l e v e l s are  and t h e r e f o r e an enhancement  in  high,  removal  2+ efficiency i t was  felt  c a u s e d b y a f u r t h e r Mg  a d d i t i o n would not be e x p e c t e d .  t h a t f o r low magnesium w a t e r s  magnesium m i g h t p r o v e  significant.  s u c h as  i n Vancouver,  However,  the e f f e c t  of  23.  CHAPTER 5 EXPERIMENTAL.METHODS • AND MATERIALS 5.1  S e l e c t i o n of  Effluent  The m a j o r i t y o f primary series  effluent  (PPE)  t h e r e s e a r c h was  from the Annacis  o f e x p e r i m e n t s was  c a r r i e d out u s i n g  prechlorinated  I s l a n d Sewage T r e a t m e n t P l a n t .  a l s o done on raw sewage  (RS)  f r o m t h e same p l a n t  i n order  t o compare t h e r e m o v a l e f f i c i e n c i e s of t h e two w a s t e  Effluent  from the Annacis  this plant  I s l a n d sewage t r e a t m e n t p l a n t was  contributes a large  a r e a number  of  5;2  Procedure  Sampling  flow into  i n d u s t r i a l waste  the Fraser  streams  River  tied into i t s  streams.  chosen  estuary  sewer  plastic  end o f  b u c k e t on a r o p e .  the primary  A sample of  about  because and  there  system.  P r e c h l o r i n a t e d p r i m a r y e f f l u e n t was o b t a i n e d b y s a m p l i n g overflow at the discharge  A  the  sedimentation basin using 10 I m p e r i a l  gallons  was  a  taken  e v e r y Monday m o r n i n g w h i c h was a d e q u a t e f o r t h e we.efc.'.s t e s t i n g . I n i t i a l l y , sa o n e l i t r e alkalinity was  titration.  changed  As  t o 10 I m p e r i a l g a l l o n s ,  t h i s was t h e m o s t In  These  convenient  to provide samples  taken for  the sample  s u f f i c i e n t sample  were t a k e n p r i o r  an  for  to the  size the  comminutors  location.  o r d e r t o e l i m i n a t e d i l u t i o n e f f e c t s c a u s e d by s t o r m w a t e r  no s a m p l i n g was d o n e w i t h i n 8 h o u r s o f t h e sewer catchment a r e a . p a r t of  r a w sewage was  the r e s e a r c h program p r o g r e s s e d ,  raw sewage e x p e r i m e n t a t i o n . as  sample of  This  p r e c a u t i o n was deemed n e c e s s a r y  t h e sewage c o l l e c t i o n s y s t e m  was a s s u m e d t o be p r e s e n t normal v a l u e of  if  1 2 0 - 1 3 0 mg/1  the c o m p l e t i o n of a r a i n storm  is  comprised of  the a l k a l i n i t y of as  CaC0„.  flows, within  because  combined sewers.  e i t h e r s a m p l e was b e l o w  a  large  Dilution the  24. 5.3  Sample  Storage All  samples were s t o r e d a t 3°C.  P r i o r to a coagulation t e s t  s a m p l e s w e r e warmed t o 20°C i n a 35°C i n c u b a t o r w h i c h u s u a l l y 1% 5.4  about  hours. Chemical  5.4.1  Preparations  Heavy M e t a l S p i k e In  of i n i t i a l of  took  the  Solutions  o r d e r to t e s t the heavy m e t a l removal e f f i c i e n c y over a  concentrations  the v a r i o u s  1000 m g / 1 .  (.5,  2.5  and 5.0  mg/1 M " ") a s e t o f s t o c k 11  solutions  1  heavy metals were prepared each h a v i n g  A volume of  range  a concentration of  200 m l was p r e p a r e d f o r e a c h m e t a l f r o m t h e  following  compounds: Heavy M e t a l Cr  3 +  Cu  2 +  Ni Zn The s t o c k  Compound CrCl .6H 0 3  2  2  CuS0,.5H„0 4 2 Ni(NO ) .6H 0  +  3  2  2  ZnS0..7H 0 4 2  2 +  o  s o l u t i o n c o n c e n t r a t i o n was n o t c h e c k e d , b u t f o r e a c h  a s p i k e d s e w a g e s a m p l e was  analysed  experiment  t o o b t a i n an e x a c t m e t a l i o n  concentra-  tion. 5.4.2  Atomic Absorption Standard  Solutions  The a t o m i c a b s o r p t i o n s t a n d a r d s o l u t i o n s diluting Fisher 5.4.3  C e r t i f i e d A.A.  standards  to the range  .05 mg/1  accurately  t o 5.0  mg/1.  Lime Dry reagent  method o f  grade C a ( 0 H )  lime addition.  lime addition i s  2  was  chosen f o r t h i s  study  as  Immediately p r i o r to usage the C a ( 0 H )  w e i g h e d a c c u r a t e l y on a S a r t o r i u s for  were prepared by  discussed  M o d e l 2442 b a l a n c e .  i n Appendix  A.  2  the p r e f e r r e d powder  S e l e c t i o n of  was  t h e method  25. 5.4.4  Magnesium i o n A 10  4  mg/1 Mg  2+  s o l u t i o n was  c a r e f u l l y p r e p a r e d f r o m MgSO .7H 0 4 ^ The e x a c t c o n c e n t r a t i o n was n o t o b t a i n e d b y a n a l y s i s b e c a u s e i t was f e l t t h a t the c h e m i c a l p u r i t y would be a c c u r a t e enough, used.  A c o n c e n t r a t i o n o f 10  4  mg/1 Mg  2+  was  considering  the s m a l l  volumes  s e l e c t e d to minimize d i l u t i o n of 2+  the c o a g u l a t i o n t e s t sample magnesium 5.4.5  Sodium  to i n c r e a s e  5.5  mg/1 a s  discussed  add  i n Appendix  CaCO^ s o l u t i o n o f NaHCO^ was p r e p a r e d and was  mg/1  Techniques  Alkalinity  described i n "Standard Methods" Heavy M e t a l  the p o t e n t i o m e t r i c t i t r a t i o n  (1).  o f h e a v y m e t a l c o n c e n t r a t i o n s was done f o l l o w i n g  atomic absorption procedures  d e s c r i b e d i n "Standard Methods"  the pretreatment procedure.  (1)  15 m i n u t e s was u s e d i n p l a c e o f  A digestion consisting  i n "Standard Methods" produced i d e n t i c a l Digestion I t was  of four i n order  (1).  t h e more t i m e c o n s u m i n g  Tests  comparing  of  technique  t h e two d i g e s t i o n  the  with  m l o f HNO^ a n d 1 m l o f HC1 t o a 50 m l s a m p l e a n d t h e n b o i l i n g f o r  different.  method  Analysis  Analysis  exception of  A.  used  tests.  A l k a l i n i t y was m e a s u r e d u s i n g  lh  The d e c i s i o n t o  t h e a l k a l i n i t y f r o m t h e n o r m a l 1 2 0 - 1 3 0 t o a p p r o x i m a t e l y 200  Analytical  5.5.2  ).  Bicarbonate 4  CaCO^ f o r c e r t a i n  5.5.1  mg/1 Mg  i n a n i o n i c f o r m r a t h e r t h a n a s MgCOH)^ i s  A 10  as  (1 m l = 1 6 . 7  the  adding about  described  procedures  results. procedures  f o r samples  found necessary  t o i n c r e a s e AA  c o n t a i n i n g l e a d were  to c o n c e n t r a t e the samples  sensitivity.  slightly  by a f a c t o r  26.  All  samples  Atomic Absorption  except z i n c were run on the J a r r a l l - A s h Model  Spectrophotomer.  5 0 0 due t o a v a i l a b i l i t y . 5.5.3  810  Z i n c w a s - r u n on t h e J a r r a l l - A s h M o d e l  T a b l e 7 summarizes  the A.A.  operating  parameters.  pH The pH was m e a s u r e d o n a n A c c u m e t M o d e l 810 pH m e t e r w h i c h was  s t a n d a r d i z e d d a i l y a t pH 1 0 . 5.6  Lime-magnesium  Coagulation Test  The d e v e l o p m e n t o f  Procedure  the t e s t procedure i s  d e t a i l e d i n Appendix  A.  TABLE 7 Instrument Operating  Metal  Lamp Current  Parameters  Nonabsorbing X  X-  Flame  Instrument  Cr  10 ma  3579  3520  reducing  Jarrall-Ash  Cu  7 ma  3247  N/A  slightly reducing  II  Pb  10 ma  2320  2316  oxidizing  II  Ni  8 ma  2170  2204  slightly reducing  2138  N/A  Zn  7.5  Misc.  ma  1)  Scale  2) F l a m e :  expansion  it  oxidizing  used i n a l l  J.A.  500  cases.  air/acetylene.  3)  Pb s a m p l e s  concentrated  4x  by.boiling.  4)  Background c o r r e c t i o n not r e q u i r e d  for  Cu a n d  Zn.  810  28. CHAPTER 6 RESULTS AND -DISCUSSION . 6 . 1 . The r e m o v a l e f f i c i e n c y o f - i n d i v i d u a l h e a v y m e t a l s f r o m P P E - U n f i l t e r e d Results 6.1.1  Chromium 3+ Figures  4 , 5 a n d 6 show t h e r e m o v a l o f C r  f r o m PPE w i t h  increasing  2+ pH and a t d i f f e r e n t Mg  dosages;  At a given lime dosage, increased. and about for  The drop  The a v e r a g e  t h e pH t e n d e d t o d r o p a s  i i i pH was a b o u t  .4 pH u n i t s  l i m e dosage i s 2+ t h e Mg  .1 pH u n i t s  a t the h i g h l i m e dosage  also  shown.  c o n c e n t r a t i o n was  a t the low l i m e dosage  (pH 1 1 4 ) .  T h i s was t h e  (pH  10)  case  a l l f i v e metals  studied. 2+ 3+ T h e e f f e c t o f Mg on Cr r e m o v a l was m o s t s i g n i f i c a n t a t t h e l o w 3+ 3+ 3+ est i n i t i a l Cr c o n c e n t r a t i o n ([Cr Ji). A t [Cr ] ^ = .5 mg/1 a r e m o v a l o f 2+ 75% was o b t a i n e d b y r a i s i n g t h e pH t o 1 0 . 0 4 . T h e a d d i t i o n a l 33 mg/1 o f Mg enhanced t h i s r e m o v a l t o 89%. b y f u r t h e r Mg  2+  The r e m o v a l was n o t s i g n i f i c a n t l y  a d d i t i o n a t t h i s pH.  A t pH 1 0 . 6 8  the Cr  e n h a n c e d f r o m 80 t o 9 1 % b y t h e a d d i t i o n o f 17 mg/1 o f Mg  3+ 2+  increased  r e m o v a l was and w i t h  only  2+  minor  i m p r o v e m e n t a t h i g h e r Mg dosages. A t pH 1 1 . 2 5 t h e a d d i t i o n o f 2+ 3+ 8 mg/lMg r e d u c e d t h e r e s i d u a l t o a p p r o x i m a t e l y .03 mg/1 C r . This could  o n l y be a p p r o x i m a t e d due t o a l a c k o f A . A . range. of  [Cr  F o r Mg 3+  additions  >_ 8 m g / l , k t h e C r  3+  residuals  About  pH's  the e f f e c t  At appears-to  17 mg/1 Mg  [Cr  3+  2+  enhanced t h e Cr  3+  concentration  at the higher  ] . w e r e a p p r o x i m a t e d a t t h i s same v a l u e . 3+ 2+ A t [Cr ] = 2 . 5 mg/1 t h e e f f e c t o f Mg i s most  pH 1 0 . 0 4 . higher  2+  s e n s i t i v i t y at t h i s  significant  levels  at  r e m o v a l f r o m 87 t o 94% a n d  diminishes.  ] ^ = 5 . 0 mg/1  t h e r e m o v a l i s v e r y h i g h a n d 8 mg/1  i n c r e a s e t h e r e m o v a l by about  i n c r e a s e i n r e m o v a l b y a Mg  2+  Mg  2% o v e r t h e e n t i r e pH r a n g e .  a d d i t i o n g r e a t e r t h a n 8 mg/1 d i d n o t  2+ An  occur  at  Cr  a> Q- 3 0  RESIDUALS(mg/l)  \  20  0 1 10.0  LIME D O S E (mg/1  FIGURE  3 +  10.50  10.68  11.25  50  .06  .04  ~.03  33  .06  .05  ~.03  17  .08  .05  -.03  8  .10  .06  -.03  0  . 14  .11  pH  II.0  LIME Mg  Cr  3  +  DOSAGE 2 +  .05  I. 5 0  415  236  PERCENT *  10.04  I  163  4  pH  REM0VAL FOR  [Cr  D O S A G E (mg / I)  Vs. pH 3 +  AND  ]. =0.50  mg/1  100 90 80  o  >  70  b  u or  60  A.  50  ® u  40  o  u.  °-  Cr *RESIDUALS(mg/l) 3  30 20  10 0  10.04  10.68  11.25  50  .10  .06  ~.03  33  . 15  . 10  ~.03  17  .15  . 1 1 ~.03  8  .26  . 13  0  .35  .19  1 10.0  LIME D0SE(mg/l)l  FIGURE  10.50  pH  163  5  LIME  3  +  REMOVAL  DOSAGE 2  +  D0SAGE  50  415  236  PERCENT Cr * Mg  II.0  1  Vs. p H A N D  F O R [Cr ].= 2.50 mg / I 3 +  (mg/1)  ~.03 .06  Cr * RESIDUALS (mq/I) 3  CL  30 M  20  10.04  10.68  50  . 14  . 1 1 -.03  33  . 18  .09  17  . 16  .1 1 - . 0 3  8  . 18  .1 1 - . 0 3  0  .30  .19  g  10 0  >^  1 10.0  LIME D0SE(mg/l)  FIGURE  10.50  pH 236  163  6  PERCENT Cr LIME * Mg  3  +  2  +  415  REMOVAL  DOSAGE DOSAGE  I 1.50  .0  Vs. pH  AND  F O R [Cr ].= 5.00mg / I 3 +  (mg/1)  11.25  ~.03  .07  32. because 6.1.2  a d d i t i o n a l Mg  2+  d i d not  f u r t h e r reduce  the r e s i d u a l a t a g i v e n  pH.  Copper Figures  increasing  7,  8 a n d 9 show t h e p e r c e n t Cu  pH a n d a t d i f f e r e n t Mg  removal appeared  2+  t o be s i g n i f i c a n t  dosages.  2+  r e m o v a l f r o m PPE  The e f f e c t  throughout  o f Mg  2+  with  o n Cu  t h e e n t i r e pH r a n g e  2+  tested. 2+  The d a t a i n d i c a t e d t h a t , a s is  required to achieve  removal i s  t h e pH i s  increased,  a lesser  t h e maximum p r a c t i c a l r e m o v a l .  amount  of  The maximum  the removal beyond which t h e r e i s o n l y minor 2+ ment w i t h i n c r e a s e d Mg dosages. A t pH 1 0 . 0 1 f o r a l l t h r e e i n i t i a l c o p p e r c o n c e n t r a t i o n s , still of  d e f i n e d as  improvement  22 t o 4 6 % ,  i n r e m o v a l up t o a t  least  33 mg/1 Mg  2+  33 t o 54% a n d 50 t o 69% w e r e o b t a i n e d f o r  .  practical improve-  there  Removal  initial  Mg  is  increases  copper  2+ concentrations  [Cu  ]  of  .5,  2.5,  5.0  mg/1 r e s p e c t i v e l y , a s a  consequence  2+ o f a Mg  a d d i t i o n of  33 mg/1.  These r e s u l t s  indicate that  the e f f e c t  of  2+ Mg  i s most s i g n i f i c a n t  at lower i n i t i a l  copper  concentrations.  This  c o n c l u s i o n i s f u r t h e r d e m o n s t r a t e d a t pH 1 0 . 5 6 w h e r e r e m o v a l i n c r e a s e s o f 2 1 . 5 t o 6 0 % , 54 t o 75% a n d 63 t o 82% w e r e o b t a i n e d i n o r d e r o f i n c r e a s i n g 2+ 2+ [Cu j ^ a s a c o n s e q u e n c e o f a d d i n g 33 mg/1 Mg . The maximum p r a c t i c a l r e m o v a l a t pH 1 0 . 5 6 i s a t 33 mg/1 Mg. The t r e n d o f i n c r e a s e d r e m o v a l w i t h increased metals  [Cu  2+  ]-at  constant  pH a n d Mg  2+  d o s a g e was  found t o be t r u e f o r  all  studied. A t pH 1 1 . 3 9  p r a c t i c a l removal. increases  2+  only  As  8 mg/1 Mg a p p e a r e d t o a c h i e v e t h e maximum 2+ t h e [Cu ] was i n c r e a s e d f r o m .5 t o 5 . 0 mg/1 r e m o v a l  o f 58 t o 7 0 . 5 % , 84 t o 92% a n d 88 t o 95% w e r e o b t a i n e d  respectively.  2+ Cu  r e s i d u a l a p p e a r e d t o r e a c h a minimum v a l u e o f  .14 -  .16  mg/1  2+ a t pH 1 1 . 3 9 appeared range  a n d Mg  dosage g r e a t e r  t o be i n d e p e n d e n t  studied.  t h a n 17 mg/1.  of the i n i t i a l  This constant  residual  copper c o n c e n t r a t i o n w i t h i n  the  10.0  LIME DOSE(mg/l)  FIGURE  10.50  168  7  pH  II.0  11.50  216  2 +  PERCENT Cu' LIME  DOSAGE  395  REMOVAL  Vs. pH  F O R [Cu ].= 0.50 mg / I 2 +  i  * Mg  2 +  AND  D O S A G E (mg/1 )  34.  1  100  r  90 80 o  70  o © or  60  >  +  CM o  5 a.  50  40 Cu'  RESIDUALS (mg/l)  30 20  10 0  10.01 10.56  11.39  50  1.04  .56  .14  33  1.08  .59  .14  17  1.15  . 70  .16  8  1.30  .93  .20  0  1.35  1.09  .38  _L_L  1 10.0  10.50  pH LIME D0SE(mg/l)|  FIGURE  168  8  I 1.50  11.0  216  PERCENT Cu LIME  2 +  DOSAGE  395  REMOVAL FOR [Cu  Vs.pH 2 +  ]  =2.50mg/l i  * Mg  2  +  DOSAGE  (mg/I  )  AND  10.0  10.50  . 0  I  1.50  pH LIME DOSE(mg/l)  FIGURE  68  9  216  PERCENT Cu LI M E * Mg  2  +  2 +  395  RE MOVAL  Vs.pH  AND  DOSAGE  FOR [Cu *]." 5.00'mg/I  DOSAGE  (mg/1 )  2  i  6.1.3  Lead Figures  10,  a n d a t d i f f e r e n t Mg 2+  2+  11 and 12 show p e r c e n t Pb additions.1  A s was  2+  removal w i t h increasing  t h e c a s e w i t h Cu  2+ , the e f f e c t  pH  of  2+  Mg  o n Pb  r e m o v a l i s most  significant  at  t h e l o w pH r a n g e .  A t pH  9.86  2+ t h e Pb  r e m o v a l was  increased-from.about  40% t o a b o u t  75% b y t h e  addition  2+ o f 33 mg/1 Mg . T h i s i n c r e a s e i n r e m o v a l a p p e a r e d t o be i n d e p e n d e n t o f 2+ 2+ i n i t i a l Pb c o n c e n t r a t i o n ([Pb ]/) over the range s t u d i e d . 2+ A t pH 1 0 . 5 6 t h e a d d i t i o n o f b e t w e e n 1 7 - 3 3 mg/1 Mg increased the 2+ 2& Pb r e m o v a l b y a b o u t 8% a n d . t h i s a p p e a r e d t o be i n d e p e n d e n t o f [Pb " ] . . A t pH 1 1 . 1 8 and 5 . 0  t h e e f f e c t o f Mg  mg/1, t h e a d d i t i o n o f  8 mg/1  2+  was m i n i m a l .  increased  At  [Pb  2+  ]^ =  t h e removal by about  2.5 2%.  At  2+ [Pb  ] ^ = .5 mg/1  t h e d a t a was i n c o n s i s t e n t  t o sample c o n t a m i n a t i o n .  The r e s i d u a l s  8 mg/1 w e r e t h e same a t pH 1 0 . 5 6 ment w i t h a l l o t h e r r e s u l t s initial 6.1.4  and m a y ' i n f a c t be i n e r r o r 2+  o b t a i n e d f o r Mg  and 1 1 . 1 8 . ((Figure  o b t a i n e d f o r any o f  dosages of  10).  This  is  in  the f i v e metals at  0  due and  disagreeany  concentration.•  Nickel  2+ F i g u r e s 1 3 , 14 a n d 15 show t h e r e m o v a l o f N i f r o m PPE w i t h 2+ 2+ i n c r e a s i n g pH a n d a t d i f f e r e n t Mg dosages. The r e m o v a l o f N i 'inoEeSsed with increasing  pH b u t i t was h a r d l y  a f f e c t e d a t a l l by t h e a d d i t i o n  of  2+ Mg  .  The o n l y  treatment of this  case  of  any  s i g n i f i c a n c e was f o r t h e h i g h pH 2+ t h e sample w i t h an i n i t i a l N i c o n c e n t r a t i o n o f v5 mg/1. In  t h e r e m o v a l was i n c r e a s e d f r o m 45 t o 57% w i t h t h e a d d i t i o n o f  o r m o r e o f Mg  «pl I .  r e m o v a l i s most 6.1.5  r e m o v a l enhancement  A s was  t h e c a s e w i t h Cu  significant  2~t* , the e f f e c t  at low i n i t i a l N i  2+  o f Mg  2H  -  on  Ni  8  mg/1  21  concentrations.  Zinc Figures  16,  17 a n d 18 show t h e r e m o v a l o f Z n  2+  with increasing  pH  a o a> °-  40 Pb  30  2 +  RESIDUALS(mg/l )  M g * * \  20 IQ 0  J  9.86 10.56  50  • 1 1  .07  .025  33  . 14  .08  .05  17  . 15  .09  .03  8  . 19  .09  .09  0  .2 9  .  10.50  II.0  II. 5 0  pM LIME D0SE(mg/l)|  FIGURE  II  1 10.0  144  228  327  10 P E R C E N T P b * R E M O V A L  Vs. pH  8  LIME « Mg  2 +  DOSAGE DOSAGE  AND  FOR [Pb ].= 0.50mg/l 2 +  (mg/1)  11.18  .10  Pb  Q)  a.  2 +  RESIDUALS(mg/l)  30  9.86  20  50 33  10  17 0  J  L  11.18  .15  .13  .14  .16  . 51 —  .65  8  0  10.56  .20  —  . 28  1.65  —  11  10.0  10.50  II. 0  11.50  pH LIME D0SE(mg/l)  FIGURE  144  II  228  PERCENT Pb L I M E * Mg  2  2 +  DOSAGE +  DOSAGE  327  REMOVAL  Vs. pH  FOR [Pb ].= 2 +  (mg/1)  AND  2.50mg/|  —  .19 .21  0)  o.  Pb  30  2 +  M g  20  RESIDUALS(mg/l)  2  \  >  50  0  10.0  10.50  9.86  10.56  11.18  .12  .09  .15  . 1 1  —  33  1.20  17  1.30  8  1.50  .33  .13  0  2.93  .64  .21  1.0  —  11.50  pH LIME D0SE(mg/l)  FIGURE  144  12  228  PERCENT Pb LIME * Mg  2  +  2 +  327  REMOVAL  DOSAGE  FOR [Pb  D0SAGE  (mg/1)  Vs. pH 2 +  ].  s  AND  5.00mg/l  —  TT  100 90 80 o o E o, cr.  +  (VI -  •z  0)  70  I-  60 50 40  o  CD * o.  30 Ni*  20 10  RESIDUALS(mg/l) 9.97  10.54  11.40  .61  .58  .29  8  .61  . 58  .28  0  .63  .61  .37  50  0  10.0  10.  50  1.0  .50  pH LIME D0SE(mg/l)  FIGURE  131  13  9 3  PERCENT Ni  2  +  39  REMOVAL  LIME  DOSAGE  * Mg  D O S A G E (mg / I)  2 +  FOR [Ni  Vs. pH 2 +  2  AND  ] = 0.50mg/1 '  41.  10.0  10.50  1.0  50  pH LIME DOSE(mg/l)  FIGURE  31  14  I9 3  PERCENT N i LIME  392  +  REMOVAL  DOSAGE  FOR [Ni  2  Vs. pH 2 +  AND  ] = 2.50mg/l i  * Mg  2  +  D O S A G E (mg/1 )  + A B N O R M A L L Y HIGH pH  VALUE(I0.92)  TT  TT  100  90 80 > 70 o E a> 6 0 or ~_  5 o  50  4  0  i_  a.  Ni  30  2  RESIDUALS(mg/l)  +  10.54  9.97 20 1.0 0  11.40  50  1.75  1.25  33  1.75  1.40  17  1.75  1.30  8  1.65  1.50  . 18  0  1.75  1.40  .28  11 50  10.50  10.0  pH LIME D0SE(mg/l)  F I G U R E 15  I 9 3  13  39  2+  P E R C E N T NT' REMOVAL LIME  DOSAGE  * Mg  D O S A G E (mg/ I)  2 +  Vs. pH  FOR [Ni ].= 2 +  2  AND  5.00mg/l  . 14 —  '  —  43.  and a t d i f f e r e n t Mg  2+  dosages.  The r e m o v a l o£ Z n • b y t h e a d d i t i o n o f Mg was m o s t  2+  2+  was s i m i l a r t o C u  A t pH 1 0 . 0 7  r e m o v a l d u e t o t h e a d d i t i o n o f 50 mg/1 o f Mg  mg/,1  the i n c r e a s e s  i n t h a t i t was  o v e r t h e e n t i r e r a n g e o f pH t e s t e d , b u t  s i g n i f i c a n t i n - t h e l o w pH r a n g e .  the 5 metals t e s t e d .  2+  For i n i t i a l  Zn  2+  2+  were the l a r g e s t  c o n c e n t r a t i o n [Zn  2+  ]  of  in any.of  o f , .5, >2a5dand" 5 . 0 r  f r o m 40 t o  and f r o m 18 t o 77 r e s p e c t i v e l y .  A t t h i s pH t h e c o n s t a n t Mg  show no i n d i c a t i o n o f  a t h i g h Mg  2+  the a f f e c t  the increases  i r i p e r c e n t r e m o v a l w e r e f r o m 20 t o 6 2 ,  converging  affected  2+  dosage  concentrations.  86.5 curves  This  2+ i n d i c a t e s t h a t d o s a g e s g r e a t e r t h a n 50 mg/1 Mg t o r e a c h t h e maximum p r a c t i c a l  might be r e q u i r e d i n  order  removal. 2+  A t pH 1 0 . 5 9  t h e maximum p r a c t i c a l  d o s a g e i n t h e 3 3 - 5 0 mg/1 r a n g e . points  for the three i n i t i a l  r e m o v a l was o b t a i n e d w i t h a Mg.  The i n c r e a s e a v e r a g e d  13;5  percentage  concentrations.  2+ t h e maximum p r a c t i c a l r e m o v a l f o r [ Z n ] . o f 2 . 5 and 2+ 5 . 0 mg/1 w a s o b t a i n e d w i t h a Mg d o s a g e o f 8 mg/1. The i n c r e a s e a v e r a g e d 2+ 9.0 p e r c e n t a g e p o i n t s . The r e s i d u a l s o b t a i n e d f o r [ Z n ] ^ =-.5 mg/1 a t pH 1 1 . 3 6 w e r e a p p r o x i m a t e l y .04 m g / 1 : Due t o a l a c k o f A . A . s e n s i t i v i t y no ?+2+ A t pH 1 1 . 3 6  significant 6.1.6  i m p r o v e m e n t was n b t i c e a B l e y b y h i f e h e d a d d i i t i d i o n f o M g M g .  Summary The d e g r e e t o w h i c h t h e a d d i t i o n o f m a g n e s i u m  ions  r e m o v a l o f t e s t e d h e a v y m e t a l s h a s b e e n shown t o b e d e p e n d e n t following: pH.pH.  .  species  improves upon.the  o f m e t a l i o n ; c o n c e n t r a t i o n o f imetfala i o n ; and  To p r o v i d e some i d e a o f t h e w o r t h o f m a g n e s i u m  reactions  a d d i t i o n , Table 8  2+ summarizes  t h e Mg .  the  a d d i t i o n s . r e q u i r e d t o o b t a i n t h e maximum  removal f o r each d i f f e r e n t set of experimental c o n d i t i o n s .  practical  10.0  LIME DOSE(mg/l)  F I G U R E 16  10.50  140  212  P E R C E N T  Zn  2  +  LIME DOSAGE * Mg  50  pH  2  +  DOSAGE  395  REMOVAL FOR [ Z n  2 +  •  (mg/1)  Vs. pH  AND  ] = 0.50mg/I i  10.0  LIME DOSE(mg/l)  F I G U R E 17  10.50  pH  140  1.0  212  P E R C E N T Zn  2  +  2  +  DOSAGE  11.  50  395  R E M O V A L Vs. pH  L I M E DOSAGE FOR [Zn * Mg  I  2 +  (mg/1)  ].=  AND  2.50mg/I  10.0  10.50  II.0  .  50  pH LIME DOSE(mg/l)  F I G U R E 18  140  212  PERCENT  Zn  * Mg  2 +  REMOVAL  2 +  LI M E D O S A G E  395  Vs. pH  AND  FOR [Zn *]. = 5.00mg/ I  DO S A G E  2  (mg/1)  TABLE 8 E f f e c t i v e Mg Dosages f o r t h e F i v e Heavy M e t a l s under D i f f e r e n t C o n d i t i o n s o f [M ] . a n d pH  5.0  .5  2.5  5.0  17  <8  +  33  33  33  8-17  <8  +  33  33  33  .  <8  +  8  8  8  .  .5  2.5  10.0  33  10.6  17  11.4  8  Initial  Concentration  Zinc  Nickel  Lead  Copper  Chromium  2.5  5.0  8  0  0  >50  38  8  8  8  33  8  8  0  0  8  .5  2.5  5.0  .5  ^33  ^33  33  17  17 8-17  .5  2.5  5.0  >50  50  pH .  +  8  +  m i n i m a l improvement  ( o n l y p r a c t i c a l where optimum r e m o v a l  required)  17-33  17-3.  8  8  48. 6.2  The r e m o v a l e f f i c i e n c y o f Unfiltered  i n PPE - F i l t e r e d v s  Results  A comparison of  the removal e f f i c i e n c i e s obtained w i t h  and u n f i l t e r e d s e t t l e d f i n a l These t a b l e s  i n d i v i d u a l metals  effluent is  shown i n T a b l e s  i n d i c a t e that the removal e f f i c i e n c y i s  to 2 percent w i t h the a d d i t i o n of a f i l t r a t i o n  step  9,  filtered  10 a n d  11.  o n l y improved about (#2 Whatman  1  filter 2+  paper)  i n the process.  The o n l y e x c e p t i o n a p p e a r s  t o be t h a t o f Zn  i m p r o v e m e n t c a u s e d b y f i l t r a t i o n was a b o u t 8 p e r c e n t a g e p o i n t s 4.4  a t pH 1 0 . 6  6.3  The r e m o v a l e f f i c i e n c y o f m i x e d m e t a l s Filtered  a n d 5.4  a t pH  11.4. f r o m PPE - U n f i l t e r e d a n d  Results  to approximately  tested. results  Unfortunately,  the  .50 mg/1 M 2+ t h e Pb  n +  w i t h each of  was u n d e r s p i k e d  the f i v e metals  to  .125 mg/1 s o  c o u l d n o t be c o m p a r e d t o t h e i n d i v i d u a l m e t a l The r e s u l t s  of  The  a t pH 1 0 ,  A s e t o f e x p e r i m e n t s was p e r f o r m e d on e f f l u e n t t h a t h a d spiked  .  of  a r e shown i n T a b l e s  these  performed.  The  results comparisons  Of t h e 12 c o m p a r i s o n s s h o w n , t h e o n l y 2+ 2+ t h r e e t h a t d i d n o t c o m p a r e v e r y w e l l a r e Zn a t pH 10 a n d N i a t pH 1 0 . 6  and 11.4.  12,  previously  runs.  t h e s e e x p e r i m e n t s were compared t o t h e  .50 mg/1 i n d i v i d u a l m e t a l r u n s p r e v i o u s l y  been  The r e a s o n  to the s l i g h t  13 a n d 1 4 .  f o r these d i f f e r e n c e s i s  differences in i n i t i a l  unknown b u t i t may b e r e l a t e d  concentrations  of t h e i n d i v i d u a l and  mixed heavy m e t a l e x p e r i m e n t s . T a b l e 15 g i v e s a c o m p a r i s o n o f metals  the percentage removals  f r o m f i l t e r e d and u n f i l t e r e d samples  w i t h mixed heavy m e t a l s i n PPE. there appears  to be o n l y minor  A s was  f o r the experiments  of  heavy  performed  the case w i t h the i n d i v i d u a l metals,  i m p r o v e m e n t i n r e m o v a l due t o  filtration.  49.  TABLE 9 P e r c e n t R e m o v a l s f o r F i l t e r e d and U n f i l t e r e d S a m p l e s o f I n d i v i d u a l Heavy M e t a l s i n P r e c h l o r i n a t e d P r i m a r y E f f l u e n t a t I n i t i a l C o n c e n t r a t i o n = .5-mg/1. pH Mg Dose  Chromium (mg/1)  Filtered  Copper  Unfiltered  F  10.0 Nickel  Unf  F  Unf  Zinc  Lead  F  Unf  F  Unf  0  75  75  22  6  6  31  20  50  44  8.33  84  82  28  9  9  51  47  62  63  16.66  -  86  44  -  -  56  47  71  71  33.33  89  89  46  -  -  67  56  73  74  50.0  89  89  54  9  9  69  62  78  78  67  78  78  75  82  82  81  83  83  84  84  pH  10.6  -  80  37  33  13.4  9  8.33  -  89  48  44  13.4  13.4  16.66  -  91  52  50  -  -  33.33  -  91  60  60  -  -  50.0  -  93  62  60  13.4  pH If*  nta min ate  0  81  13.4  S3  83  86  87  o  11.4  0  >95  >95  60  56  42  45  89  90  83  80  8.33  >95  >95  73  71  55  58  93  91  93  83  16.66  >95  >95  -  -  -  -  93  92  95  94  33.33  >95  >95  73  73  -  -  92  91  95  93  50.0  >95  >95  75  73  55  57  -  -  95  95  50. TABLE  10  P e r c e n t Removals f o r F i l t e r e d and U n f i l t e r e d Samples of I n d i v i d u a l Heavy M e t a l s i n P r e c h l o r i n a t e d P r i m a r y E f f l u e n t a t I n i t i a l C o n c e n t r a t i o n =.2.5 mg/1  Mg Dose (mg/1)  Copper  Chromium Filtered  10.0  Unfiltered  F  Unf  F  Unf  0  88  87  33  33  39  44  8.33  91  90  47  43  42  39  16.66  95  94  52  50  -  -  33.33  93  94  60  53  -  -  50.0  95  96  61  55  -  42  pH  Lead.  Zinc  Nickel F  Con tamin;ated  pH  Unf  F  Unf  40  45  34  58  78  _  73  81  74  73  85  -  85  88  80  10.6  -  -  0  93  93  55  54  57  58  75  70  8.33  95  95  63  60  62  63  89  78  89  87  16.66  96  96  71  70  -  -  90  85  92  -  33.33  96  96  77  75  -  -  91  89  95  -  50.0  97  97  77  76  58  -  92  91  94  94  pH  11.4  0  97  97  85  84  87  94  93  84  95  92  8.33  99  99  92  92  94  87  96  82  96  93  16.66  99  99  93  93  -  -  96  86  97  -  33.33  99  99  94  94  -  -  93  86  50.0  99  99  94  94  95  96  94  87  -. 98  94 95  51. TABLE  11  P e r c e n t Removals f o r F i l t e r e d and U n f i l t e r e d Samples o f I n d i v i d u a l Heavy M e t a l s i n P r e c h l o r i n a t e d P r i m a r y E f f l u e n t a t I n i t i a l C o n c e n t r a t i o n =5.0 mg/1 pH 10.0 Mg Dose (mg/1)  Copper  Chromium  Lead  Zinc  Nickel  F  Unf  F  Unf  60  '31  18  42  63  63  40  18  70  66  60  60  57  48  74  72  69  60  60  70  64  76  75  72  60  60  81  77  -  Filtered  Unfiltered  F  Unf  F  0  95  94  56  50  56  8.33  97  97  62  60  16.66  97  97  68  33.33  97  97  50.0  98  97  Unf  pH 10.6  0  97  96  66  63  68  68  85  79  90  87  8.33  98  98  74  73  67  66  89  85  94  94  16.66  98  98  78  75  71  71  94  89  96  -  33.33  99  98  83  82  71  68  -  92  98  97  50.0  98  98  84  83  74  72  75  94  98  98  pH 11.4  0  99  99  89  88  95  95  8.33  99  99  95  95  97  97  16.66  99  99  96  96  -  -  33.33  99  99  97  97  -  -  50.0  99  99  -  97  97  97  89 OJ 4-1  •H a  o o  96  98  98  98  93  -  99  99  98  99  99  98  97  TABLE 12 Comparison of t h e I n d i v i d u a l M e t a l Removals t o t h e Combined R e m o v a l s a t pH 1 0 . 0 ( A p p r o x . )  « g  2  +  Dose (mg/1) 0  Residual  Comb  Ind  Comb  Ind  Comb  Combination Ind  Individual  Zinc  Nickel  Copper  Chromium  Metal  Removal  Res  Rem  Res  Rem  Res  Rem  Res  Rem  Res  Rem  Res  Rem  Res  Rem  75.0  .14  73.1  .42  22  .38  34.5  .63  6.0  .47  16.1  .36  20  .26  51.9  .14  8.33  .10  82.1  .09  82.7  .39  28  .34  41.4  .61  9.0  .47  16.1  .24  46.7  .20  63.0  16.66  .08  85.7  .09  82.7  .30  44  .34  41.4  -  -  .47  16.1  .24  46.7  .18  66.7  33.33  .06  89.3  .07  86.5  .29  46  .32  44.8  -  -  .47  16.1  .20  55.6  .10  81.5  50.0  .06  89.3  .07  86.5  .25  54  .34  41.4  .61  9.0  .47  16.1  .17  62.2  .12  77.8  Initial Cone.  .56  A v g pH  .54  .52  10.04  9. 94  10.01  .67  .58  9 .94  9 . 97  .45  .56 9 .94  10 07  .54 9. 94  TABLE  13  Comparison of the I n d i v i d u a l M e t a l Removals M e t a l R e m o v a l s a t pH 1 0 . 6 0 (Approx.)  „, 2+ Mg Dose (mg/1)  Chromium  Residual  Removal  Combined  Zinc  Nickel  Copper  C o m b i n a t i o n Ind  Individual  to the  Ind  Comb  Ind  Comb  Comb  Res  Rem  Res  Rem  Res  Rem  Res  Rem  Res  Rem  Res  Rem  Res  Rem  0  .11  80.4  .04  92.7  .35  33  .26  56.1  .61  9  .49  15.5  .16  66.7  .19  61.4  8.33  .06  89.3  .05  90.9  .29  44  .24  60  .58  13.4  .46  20.7  .12  75  .10  80  16.66  .05  91.1  <.03  >95  .26  50  .23  61.7  -  -  .40  31  .09  81  .08  84  33.33  .05  91.1  <.03  >95  .21  60  .25  58.3  -  -  .40  31  .09  81  .09  82  50.0  .04  92.8  <.03  >95  .21  60  .23  61.7  .58  13.4  .38  34.5  .08  83.3  .07  86  Initial Cone.  .56  A v g pH  .55 10.68  .52 10 .56  10 56  .60 10 .56  .67 10 .54  .58 10 56  .49 10.59  .50 10.56  TABLE 14 Comparison of t h e I n d i v i d u a l M e t a l Removals M e t a l R e m o v a l s a t pH 1 1 . 4 ( A p p r o x . )  Chromium M  g  to t h e Combined  Copper  Nickel  Zinc  2 +  Dose (mg/1)  Individual Residual  C o m b i n a t i o n Ind Removal.  Comb  Ind  Comb  Ind  Res  Rem  Res  Rem  Res  Rem  Res  Rem  Res  Rem  Comb  Res  Rem  Res  Rem  !  0  -.05  91  <.02  >96  .23  56  .20  66.7  .37  44.7  .30  48.3  .045  90  .045  91  8.33  ^.03  >95  <.02  >96  -  -  .19  68.3  .28  58.2  .32  44.8  .040  9 1 . 1 .045  91  16.66  ^.03  >95  <.02  >96  .15  71  .175  70.8  -  -  .27  53.4  .0.35 9 2 . 2  33.33  ^.03  >95  <.02  >96  .14  73  .17  71.7  -  -  .28  51.7  .040  50.0  ^.03  >95  <.02  >96  .14  73  .165  72.5  .29  56.7  .32  44.8  -  Initial Cone. A v g pH  .52  .55 1 1 . 25  .52 11.13  .60 11.39  11.13  .67 11 .40  .58  .045  91  9 1 . 1 .045  91  -  .45 11.13  1 1 . 36  .040  92  .50 11.13  55. TABLE 15 P e r c e n t Removals f o r F i l t e r e d and U n f i l t e r e d Samples of C o m b i n a t i o n s o f Heavy M e t a l s i n P r e c h l o r i n a t e d Primary Effluent pH 1 0 . 0 Mg  Dose (mg/D  Zinc  Unf  F  Unf  16.1  16.1  -  -  41.4  17.9  16.1  -  -  34.5  41.4  17.9  16.1  -  -  86.5  41.4  44.8  -  16.1  -  -  86.5  -  41.4  -  -  -  -  Unf  Filtered  Unfiltered  F  75  73.1  31.0  34.5  8.33  82.7  82.7  37.9  16.66  84.6  82.7  33.33  88.5  50.0  88.5  0  Nickel  Copper  Chromium  2 +  F  pH 1 0 . 6 0  -  92.7  54.7  56.1  31  15.5  80.0  61.4  31  20.7  81.4  80.0  8.33  >94.5  90.9  58.3  60.0  16.66  >94.5  94.5  60.0  61.7 36.2  31.0  36.0  84.0  33.33  >94.5  94.5  58.3  59.0  37.9  31.0  82.0  82.0  50.0  >94.5  94.5  55.0  61.7  37.9  34.5  32.0  86.0  pH 1 1 . 4 0  >96.3  >96.3  64.2  66.7  46.6  48.3  -  -  8.33  >96.3  >96.3  65.0  68.3  46.6  44.8  -  -  16.66  >96.3  >96.3  -  70.8  53.4  53.4  -  -  33.33  >96.3  >96.3  68.3  71.1  53.4  51.7  -  -  50.0  >96.3  >96.3  70.0  72.5  44.8 j 44.8  -  56.  6.4  T h e r e m o v a l e f f i c i e n c y o f m i x e d m e t a l s f r o m Raw Sewage - U n f i l t e r e d a n d Filtered  Results  A s e t o f e x p e r i m e n t s w e r e p e r f o r m e d o n r a w sewage t h a t h a d spiked to approximately The r e s u l t s results  of  .50 mg/1 M ^ w i t h  Comparisons  a r e shown i n T a b l e s 1 6 ,  r e s u l t s w e r e o b t a i n e d f o r Pb The c o m p a r i s o n s (Tables  17 a n d 18)  i n 8 out of  the f i v e heavy  metals.  t h e s e e x p e r i m e n t s were t h e n compared t o t h e m i x e d m e t a l  performed on PPE.  efficiencies  each of  been  2+  for  of  the r e s i d u a l s  17 a n d 1 8 .  , t h e i n d i v i d u a l Pb  The two s e t s  removal  S i n c e no m i x e d m e t a l P P E 2+  r e s u l t s were  t h e e x p e r i m e n t s d o n e a t pH 1 0 . 6  i n d i c a t e t h a t t h e two s e t s  t h e 10 c a s e s .  and t h e  of r e s u l t s  are  substituted.  and  11.4  comparable  of d a t a t h a t were not  comparable  2+ were i n c o n s i s t e n t T a b l e 18 - Z n  2 +  i n opposite direction.  a t pH  ( T a b l e 17 - Pb  a t pH 1 0 . 6  and  11.4).  The c o m p a r i s o n o f  t h e e x p e r i m e n t s d o n e a t pH 1000  i n d i c a t e s a s u b s t a n t i a l improvement 2+  (Table  i n m e t a l r e m o v a l when u s i n g  16)  raw  sewage.  A l l metals except N i  showed a n i n c r e a s e i n r e m o v a l e f f i c i e n c y .  sewage s a m p l e u s e d f o r  t h e pH 10 e x p e r i m e n t was a d i f f e r e n t s a m p l e t h a n  used f o r sample).  t h e pH 1 0 . 6  and 11.4  experiments  that  The pH 10 r a w sewage may h a v e b e e n c h e m i c a l l y d i f f e r e n t , a l t h o u g h  T a b l e 19 c o m p a r e s  The s m a l l i n c r e a s e i n r e m o v a l e f f i c i e n c y  a p p r o x i m a t e l y as found f o r mixed samples  The E f f e c t of A l k a l i n i t y on Heavy M e t a l A set of  abnormal.  t h e u n f i l t e r e d and f i l t e r e d r e m o v a l e f f i c i e n c i e s  t h e raw sewage e x p e r i m e n t s .  caused by f i l t r a t i o n i s 6.5  raw  ( w h i c h w e r e b o t h d o n e o n t h e same  t h e r e a c t i o n pH and r e q u i r e d l i m e d o s a g e w e r e n o t  for  The  of  PPE.(1-2%).  Removal  e x p e r i m e n t s was p e r f o r m e d t o d e t e r m i n e t h e e f f e c t s  i n c r e a s e d a l k a l i n i t y on t h e r e m o v a l o f h e a v y m e t a l s f r o m P P E .  It  was  of felt  TABLE 16  Comparison of the Removal E f f i c i e n c i e s of C o m b i n a t i o n s of M e t a l s i n P r e c h l o r i n a t e d P r i m a r y E f f l u e n t (PPE) and Raw Sewage (RS) a t pH  Chromium Mg Dose (mg/1)  PPE  RS  Res.idual Removal  Lead  Copper PPE  Res  Rem  RS  Res  Nickel  Individual  Rem  Res  Rem  Res  59.8  RS  RS  Rem  Res  Rem  Res  Rem  Res  1.15  43.6  .28  36.9  .47  L6.1  .43  L7.3  .26  -  .75  63.2  -  .47  L6.1  -  .04  93.1  .38  34.5  .19  8.33  .09  82.7  -  -  .34  41.4  -  16.66  .09  82.7  .04  93.1  .34  41.4  .18  71.4  .60  70.6  .28 i 16.9  -  -  33.33  .07  86.5  .03  94.8  .32  44.8  .165 7 3 . 8  .54  73.5  .24  88.8  -  -  50.0  .07  86.5  .03  94.8  .34  41.4  .17  73.0  .45  '77.9  .20  30.7  .47  ' A v g pH  9.94  9.92  PPE  Res  73.1  .58  •  Rem  . 14  152  Zinc  PPE  0  Initial Cone.  10.0.  -  16.1  RS Rem  Res  Rem  51.9  .08  82.4  .20  53.0  -  .18  56.7  .07  84.6  L8.3  .10  81.5  .07  84.6  • .45 L3.5  .12  77.8  .07  84.6  -  • 43 L7.3 42.5  .58  .63  2. 04  2.14  56  52  .54  9. 94  9. 92  9.88  9.92  9 . 94  9 . 92  9. 94  I n d i v i d u a l Lead d a t a used i n p l a c e of Lead r e s u l t s were c o n c e n t r a t e d 4x.  c o m b i n a t i o n PPE L e a d  data.  -  .46  9 92  TABLE 17 Comparison of the Removal E f f i c i e n c i e s of Combinations of Metals i n Prechlorinated Primary Effluent (PPE) and Raw Sewage (RS) at pH 10.60.  Mg Dose  |  Residual Removal  (mg/1)  Res  Rem  Res  .02  96.6 .26  Rem  Res  Rem  56.1  .30 62.9  .45  77.9  Rem  Res  PPE  RS  Individual  RS  PPE  RS  PPE  2 +  Nickel  Lead  Copper  Chromium  Zinc RS  PP E  •  ii  RS  Rem  Res  Rem  .18 92.1 .49  15.5  .47  9.6  .19 61.4  Res  Rem  Res  i  Res  Rem  Res  Rem  .11  76. 6  0  .04  92.7  8.33  .05  90.9  c.02 >96.6 .24  60  .28 64.5  .37  81.8  .14 93.9 .46  20.7  .47  9.6  .10  80  .10  78. 7  16.66  < .03  >95  = .02 >96.6 .23  61.7  .29 63.3  .35  82.8  .14 93.9 .40  31  .47  9.6  .08  84  -  -  33.33  <.03  >95  = .02 >96.6 .25  58.3  .27 65.8  .33 83.8  .12 94.7  31  .43 17. 3  .09  82  .095 79.8  50.0  <.03  >95  = .02 >96.6 .23  61.7  .25 68.4  .28 86.3  .16 93.C .38  34.5  .45 13.5  .07  86  .08  1  Initial Cone. Avg pH  .40  i  .55 10. 56  ._  57  .60  .79  2. 04  2 .28  .58  .52  .50  .47  10 .67  10 .56  10. 67  10. 56  10 .67  10. 56  10. 67  10. 56  10. 67  •  " i n d i v i d u a l Lead data used i n place of combination PPE Lead data. Lead r e s u l t s concentrated 4x.  83  oo  TABLE  18  Comparison of the Removal E f f i c i e n c i e s of Combinations of M e t a l s i n P r e c h l o r i n a t e d P r i m a r y E f f l u e n t (PPE) and Raw Sewage (RS) a t pH  Chromium Mg Dose (mg/1)  PPE  2 +  RS  R e s i d u a l Removal  Lead  Copper PPE  Res  Rem  Res  RS Rem  11.40.  Nickel  Individual  RS  PPE  Zinc RS  Res  Rem  Res  Rem  Res  Rem  Res  Rem  Res  .20 6 6 . 7  .21  73.4  .40  80.4  .195  91.4  .30  48.3  .35  .19  .195 75.3  .35  82.8  .16  93  .32  93  • Rem  PPE  RS Rem  Res  Rem  3 2 . 7 .045  91  .08  83  44.8  .30 4 2 . 3 .045  91  .07  85.1  .27  53.4  .25  5 1 . 9 .045  91  .07  85.1  Res  0  <.02  >96  <.02  >96  8.33  <.02  >96  <.02  *>96  16.66  <.02  >96  <.02  >96  .175 7 0 . 8  .18  77.2  .13  93.6  .16  33.33  <.02  >96  <.02  >96  .17  71.7  .21  73.4  .15  92.6  .085  96.3  .28  51.7  .30  4 2 . 3 .045  91  .09  80.9  50.0  <.02  >96  <.02  >96  .165 7 2 . 5  .16  79.7  .10  95.1  .085  96.3  .32  44.8  .30 4 2 . 3 .040  92  .07  85.1  Initial Cone.  .55  A v g pH  11.13  .57 1 1 . 16  68.3  .60 11 .13  .79 11 16  2. 04  2 . 28  1 1 . 18  1 1 . 16  I n d i v i d u a l Lead d a t a used i n p l a c e of Lead r e s u l t s c o n c e n t r a t e d 4x.  C  >8  1 1 . 13  c o m b i n a t i o n PPE L e a d  data  .52  .50  .47  1 1 . 16  1 1 . 13  11 .16  T A B L E 19 E e r c e n t "Removals f o r F i l t e r e d and U n f i l t e r e d S a m p l e s o f C o m b i n a t i o n s o f H e a v y M e t a l s i n Raw Sewage pH 1 0 . 0 2+ Mg Dose (mg/D  Chromium  M  0 8.33  Copper  Filtered  Unfiltered  93.1  93.1  -  -  Nickel  Unf  F  68.3 69.8  -  -  F  Zinc'  Unf  F  13.5 17.3  JO.2  82.4  -  -  -  -  Unf  16.66  93.1  93.1  69.8 71.4  17.3 17.3  30.2  84.6  33.33  94.8  94.8  74.6 73.8  1 3 . 5 1 8 . 31  30.2  84.6  50.0  94.8  94.8  -  73.0  17.3 13.5  -  84.6  pH 1 0 . 6 96.6  96.6  65.8 62.9  13.5  9.6  30.9  76.6  8.33  ^96.6  >96.6  70.9 64.5  17.3  9.6  78.7  78.7  16.66  >96.6  >96.6  70.9 63.3  17.3  9.6  30.9  -  33.33  >96.6  >96.6  70.9 65.8  17.3 17.3  78.7  79.8  50.0  >96.6  >96.6  68.4 68.4  17.3 13.5  79.8  83.0  0  P  H  11.4  0  >96.6  >96.6  71.5 73.4  46.1 32.7  75.5  83.0  8.33  >96.6  >96.6  75.9 75.3  49.0 42.3  80.9  85.1  16.66  >96.6  >96.6  79.7  77.2  59.6 51.9  SI.9  85.1  33.33  >96.6  >96.6  81  78,4  5 1 . 9 42'. 3  81.9  80.9  50.0  >96.6  >96.6  78.5 79.7  50  81.9  85.1  42.3  61.  t h a t s u c h a d d i t i o n c o u l d be b e n e f i c i a l t o t h e m e t a l r e m o v a l p r o c e s s there i s  because  s t o i c h i o m e t r i c a l l y i n s u f f i c i e n t a l k a l i n i t y to p r e c i p i t a t e a l l  the  2+ Ca ratio  as  CaCO^ f o r  the three average  of a l k a l i n i t y to l i m e i s  averaged  l i m e dosages were: The e x p e r i m e n t s  performed at  1:1  lime dosages. whereas  1 : 1 . 6 , 1:2.4  The  the r a t i o s and  stoichiometric for  duplicated w i t h the a l k a l i n i t y spiked  three  1:4.2.  on t h e i n d i v i d u a l h e a v y m e t a l s  t h e n a t u r a l PPE a l k a l i n i t y o f  the  1 2 0 - 1 3 0 mg/1  to l e v e l s  of  ([M as  n +  ]  =2.5  CaCO^,  The e x p e r i m e n t s w e r e p e r f o r m e d a t t h e i n t e r m e d i a t e  dosage r a t h e r  than the h i g h l i m e dosage because 2+  (+90%) a t t h e h i g h l i m e d o s a g e ( e x c e p t N i be d i f f i c u l t The r e s u l t s There  to d i s t i n g u i s h of  the experiments  does n o t appear  at l e a s t  significant  t o b e any  )  t h a t i t was  i n removal  a r e p l o t t e d on F i g u r e s  up t o t h e i n t e r m e d i a t e l i m e d o s a g e .  felt  19,  sodium  lime  t h e r e m o v a l s w e r e so  differences  significant  were  1 8 0 - 2 0 0 mg/1 u s i n g  bicarbonate.  mg/1,  that  it  high  would  efficiency.  20 a n d  d i f f e r e n c e i n removal  21. efficiency*  62.  100 0  oF 90  p H = 10.7  80 o > o  6 *  #  70  o  Alka Unity  = 1 9 8 mg  /I  Alkalinity  = 120 mg/ I  60  5 0  40  30  8  17  33  Mg 2 + D o s a g e  50  (mg / I )  F I G U R E 19 P E R C E N T C r R E M O V A L V s . M g D O S A G E FOR D I F F E R E N T A L K A LI N I T I E S . 3 +  2 +  63.  FIGURE 20 P E R C E N T Z n FOR  2 +  R E M O V A L Vs. M g D O S A G E  DIFFERENT  2 +  A L K A LI Nl T l E S .  64.  F I G U R E 21 P E R C E N T C u R E M O V A L Vs. M g D O S A G E FOR D I F F E R E N T A L K A L I N I T I E S 2 +  2 +  65. CHAPTER 7 CONCLUSIONS 7.1  The E f f e c t i v e n e s s  7.1.1  o f Mg  2+  at Various  pH's  General 2+ a)  The e f f e c t o f Mg  on t h e r e m o v a l o f h e a v y m e t a l s  is  most  s i g n i f i c a n t when u s e d i n c o n j u n c t i o n w i t h l o w l i m e t r e a t m e n t (pH 1 0 . 0 ) . b ) The g r e a t e s t r e m o v a l s w e r e f o u n d a t h i g h l i m e t r e a t m e n t (pH At t h i s • 7.1.2  pH t h e e f f e c t o f Mg  Individual;Metals  in  2+  was  significant  f o r Cu  11.4)  2+ 2+ • and Zn only.  PPE  2+ 2+ T h e e f f e c t o f Mg was m o s t s i g n i f i c a n t f o r Z n w i t h major 2+ 2+ i n f l u e n c e o n Cu a n d Pb removal also being noted. a)  b)  to i t s  T h e r e was v e r y g o o d r e m o v a l f o r C r -30 low s o l u b i l i t y product (ksp = 1 0 ). c) The r e m o v a l o f N i  2+  3+  i n the absence  was p o o r a n d t h e e f f e c t o f Mg  2+  2+  o f Mg  due  was  insignificant. 7.1.3  Mixed Metals a)  in  PPE  The r e m o v a l o f m e t a l s d o e s n o t a p p e a r  presence of other metal ions  t o be a f f e c t e d b y  i n s o l u t i o n a t t h e same i n i t i a l  The r e m o v a l e f f i c i e n c y o f e a c h m e t a l i n t h e m i x t u r e was removal e f f i c i e n c y of 7.1.4  Mixed Metals a)  7.2  Residual a)  concentration.  comparable  to  the  itself.  i n Raw Sewage  The r e m o v a l o f m i x e d m e t a l s  t h a t from PPE. 10-15% to get  t h a t m e t a l when t r e a t e d b y  the  There was, however,  f r o m raw sewage was c o m p a r a b l e  an i n c r e a s e  i n r e q u i r e d l i m e dosage  to of  t o t h e same r e a c t i o n p H . Metals  i n the S e t t l e d  F i l t r a t i o n of  Supernatant  the supernatant  increased the removal e f f i c i e n c y  66.  b y o n l y 1-2 b) beakers  percentage Since  points.  the supernatant  process.  need f o r f i l t r a t i o n i n t h i s  a)  There i s  2+  simulate the  Removal so as  to  not  the i n t e r m e d i a t e pH.  The e f f e c t o f a l k a l i n i t y a t t h e h i g h pH c o u l d n o t b e  The P o t e n t i a l o f Mg a)  do n o t  required to e s t a b l i s h  s u f f i c i e n t a l k a l i n i t y i n the wastewater  due t o a l a c k o f a n a l y t i c a l  from  process.  i n h i b i t h e a v y m e t a l r e m o v a l up t o a t l e a s t b)  these removals  F u r t h e r work i s  The E f f e c t o f A l k a l i n i t y o n H e a v y M e t a l  7.4  were c a r e f u l l y p i p e t t e d  t h a t h a d b e e n s e t t l e d f o r 30 m i n u t e s ,  an a c t u a l f l o w t h r o u g h  7.3  samples  researched  sensitivity.  for Full  A rough comparison  Scale  of high  Treatment l i m e treatment vs  intermediate lime  2+ plus is  Mg  treatment i s  p r e s e n t e d i n A p p e n d i x B.  r e q u i r e d , the comparison  indicates  Although  further  research  t h a t the combined t r e a t m e n t might  be  cheaper. b)  This  type of process  i.  For the r e d u c t i o n of heavy m e t a l c o n c e n t r a t i o n s  waste streams ii.  prior  Incorporation  might be a p p l i c a b l e i n the f o l l o w i n g  to t h e i r d i l u t i o n i n municipal  w i t h i n the primary  of  industrial  sewers;  treatment process.  r e m o v a l and r a p i d m i x i n g m i g h t be a c h i e v e d s i m u l t a n e o u s l y , that the only major a d d i t i o n s w o u l d be f l o c c u l a t i o n and  to a primary  recarbonation.  areas:  treatment flow  Grit so stream  67.  BIBLIOGRAPHY  1.  APHA, AWWA, WPCF. " S t a n d a r d M e t h o d s Wastewater", 1 4 t h E d i t i o n (1976).  f o r t h e E x a m i n a t i o n o f Water and  2.  A r g o , D.G. and C u l p , G . L . "Heavy M e t a l Removal i n Wastewater Treatment P r o c e s s e s : P a r t I", W a t e r a n d Sewage W o r k s , V o l . 1 1 9 : 2 , p . 6 2 , ( A u g u s t 1972)  3.  A r g o , D.G. and C u l p , G . L . "Heavy M e t a l Removal i n Wastewater Treatment P r o c e s s e s : P a r t I I " , W a t e r a n d Sewage W o r k s , V o l . 1 1 9 : 2 , p . 1 2 8 , (September 1972).  4.  B.C. R e s e a r c h . "Water Q u a l i t y S t u d i e s i n t h e Lower F r a s e r R i v e r " , P r e p a r e d f o r t h e G r e a t e r V a n c o u v e r Sewerage and D r a i n a g e D i s t r i c t , (May 1 9 7 3 ) .  5.  B e n e d i c t , A . H . H a l l , K . J . and Koch, F.A. "A P r e l i m i n a r y Water Q u a l i t y Survey o f t h e Lower F r a s e r R i v e r S y s t e m " , Westwater R e s e a r c h C e n t r e , U n i v e r s i t y o f B r i t i s h C o l u m b i a , T e c h n i c a l Report No. 2, ( A p r i l 1973).  6.  B a r t h , . E . F . a n d o t h e r s . "Summary R e p o r t o n t h e E f f e c t s o f H e a v y M e t a l s o n t h e B i o l o g i c a l T r e a t m e n t . P r o c e s s e s " , Journ. WPCF, V o l . 3 7 , p. 90 (1965).  7.  B a r t h , E . F . and o t h e r s . " F i e l d Survey o f F o u r M u n i c i p a l Wastewater T r e a t m e n t P l a n t s R e c e i v i n g M e t a l l i c W a s t e s " , Journ. WPCF, V o l . 3 7 , p. 1 1 0 1 ( 1 9 6 5 ) .  8.  B l a c k , A . P . , DuBose, A . T . and Vogh, R.P. " P h y s i c a l - C h e m i c a l Treatment of M u n i c i p a l Wastes by R e c y c l e d Magnesium C a r b o n a t e " , EPA-660/2-74-055 (June 1 9 7 4 ) .  9.  B l a c k , A . P L and Thompson, C G . " P l a n t S c a l e S t u d i e s o f t h e Magnesium C a r b o n a t e W a t e r T r e a t m e n t P r o c e s s " , E P A - 6 6 0 / 2 - 7 5 - 0 0 6 (May 1 9 7 5 ) .  10.  Brouzes, R . J . P . "The Use o f Lime i n t h e Treatment of M u n i c i p a l w a t e r s " , Research Report No. 2 1 , Environment Canada.  Waste-  11.  C u l p , R.L. and C u l p , G . L . "Advanced Wastewater T r e a t m e n t " , Van N o s t r a n d R e i n h o l d Company ( 1 9 7 1 ) .  12.  G r i e v e , D. a n d F l e t c h e r , K. " T r a c e M e t a l s i n F r a s e r D e l t a G e o l o g i c a l Survey o f Canada, P r o j e c t 740062.  13.  H a l l , K . J . , Y e s a k i , J . and Chan, J . " T r a c e M e t a l s and C h l o r i n a t e d Hydrocarbons i n t h e Sediments o f a M e t r o p o l i t a n Watershed", Westwater Research Centre, U n i v e r s i t y of B r i t i s h Columbia, T e c h n i c a l Report No. 10 (May 1 9 7 6 ) .  Sediments",  68.  14.  H a l l , K . J . A s s i s t a n t P r o f e s s o r , Department of C i v i l E n g i n e e r i n g , U n i v e r s i t y o f B r i t i s h C o l u m b i a , P e r s o n a l C o m m u n i c a t i o n (December  1976).  15.  L a n g i e r , W.F. " E f f e c t s o f . T e m p e r a t u r e o n t h e pH o f N a t u r a l J . AWWA, V o l . 3 8 , p . 179 ( F e b r u a r y 1 9 4 6 ) .  Waters",  16.  L a r s o n , T . E . , L a n e , R.W. a n d N e f f , C . H . " S t a b i l i z a t i o n o f i n H y d r o x i d e i n t h e S o l i d s C o n t a c t P r o c e s s " , J ; AWWA, 5 1 : (December 1 9 5 9 ) .  17.  Lecompte, A.R. "Water R e c l a m a t i o n by Excess Lime Treatment of T a p p i , V o l . 4 9 , No. 1 2 , p. 1 2 1 - 1 2 4 ( D e c e m b e r 1966).  18.  L i n d s t e d t , JWPCF, V o l . 4 3 , p.  19.  M c K e e , M . E . a n d W o l f , H.W. " W a t e r Q u a l i t y C r i t e r i a " , S e c o n d E d i t i o n , P u b l i c a t i o n 3-A, C a l i f o r n i a S t a t e Water R e s o u r c e s C o n t r o l B o a r d .  20.  R i a z , M. " R e m o v a l o f H e a v y M e t a l s U s i n g G r a n u l a r C o a l " , M . A . S c . D i s s e r t a t i o n , U n i v e r s i t y of B r i t i s h Columbia (August, 1974).  21.  Rush, R . J . "Magnesium-Lime P r o c e s s f o r D e c o l o u r i z a t i o n of K r a f t M i l l E f f l u e n t s " , M.A.Sc. D i s s e r t a t i o n , U n i v e r s i t y of B r i t i s h Columbia ( A p r i l , 1976).  22.  S a b a d e l l , J . E . ( E d i t o r ) . " T r a c e s of Heavy M e t a l s i n P r o c e s s e s and M o n i t o r i n g " , E P A - 9 0 2 / 9 - 7 4 - 0 0 1 , p. 5 7 .  23.  S a r t o r , J . D . and B o y l , G.B. " W a t e r P o l l u t i o n A s p e c t s o f S t r e e t C o n t a m i n a n t s " , E . P . T e c h n o l o g y S e r i e s , E P A - R 2 - 7 0 - 0 8 1 (November  24.  Stumm, W. a n d M o r g a n , N . Y . , N.Y. (1970).  25.  T a n n e r , G . , T r a s o l i n i , G . and N e m e t h , L. " A S t u d y o n W a s t e w a t e r C h a r a c t e r i s t i c s o f G r e a t e r V a n c o u v e r Sewage T r e a t m e n t P l a n t s a n d M a j o r S e w e r s " , R e p o r t EPS 5 - P R - 7 3 - 1 1 (December 1 9 7 3 ) .  26.  Thompson, C . G . , S i n g l e y , J . E . and B l a c k , A . P . "Magnesium C a r b o n a t e R e c y c l e d C o a g u l a n t " , J o u r n . AWWA P a r t I, p . 1 1 - 1 9 ( J a n u a r y 1 9 7 2 ) .  27.  T r a v e r s , A. and N o u v e l . "On t h e S o l u b i l i t y o f Magnesium H i g h T e m p e r a t u r e s " , C o m p t . Rend ( F r . ) 1 8 8 : 499 (1929).  Magnesium 1551  Effluent",  1507.  J . J . "Aquatic Chemistry",  Water-Removal  Surface 1972).  Wiley-Interscience,  Hydroxide  A  at  69.  APPENDIX A TEST PROCEDURE.DEVELOPMENT 1.  Introduction Due to the l i m i t e d amount of work that has been done using the  lime-magnesium process,a test procedure had to be f i r s t developed that would give reproducible r e s u l t s .  The t e s t procedure developed by Rush (21)  for colour removal from k r a f t m i l l effluents was used as a base from which a s a t i s f a c t o r y procedure was developed. An o u t l i n e of the t e s t procedure development i s presented i n the following s e c t i o n to give some i n s i g h t i n t o the p r a c t i c a l problems that may concern future 2.  researchers.  Development of the Jar Test Procedure The main factors that were expected to affect trace metal removal  included i ) time (of r a p i d mixing, f l o c c u l a t i o n and s e t t l i n g ) i i ) mixing speed i i i ) pH s t a b i l i z a t i o n i v ) the a l k a l i n i t y of the sewage 2+ v) tthe dosage and method of Mg  addition  v i ) 'the dosage and method of lime a d d i t i o n I n i t i a l j a r t e s t s were c a r r i e d out on 600 ml samples of PPE to see i ) the effect of the a l k a l i n i t y of the sewage on pH s t a b i l i s a t i o n , i i ) i f the rapid mix times recommended by Rush (21) would be s a t i s f a c t o r y for heavy metal removal ( i t was f e l t that pH s t a b i l i z a t i o n was'important i n that i t i n d i c a t e d the p r a c t i c a l completion of the p r e c i p i t a t i o n reactions and thus the completion of the rapid mix time). follows:  The i n i t i a l j a r tesit's were done as  70.  i)  A 600 m l s a m p l e o f P P E was l i m e d t o t h e p H r a n g e  by a p r e d e t e r m i n e d s l u g ii)  to  11.3  dose.  The pH was m o n i t o r e d  iii)  10.8  A r a p i d mix  (100  continuously.  rpm) was m a i n t a i n e d u n t i l t h e pH h a d  stabilized. iv) until  The s a m p l e s  an a d e q u a t e v)  was  were then a l l o w e d to f l o c c u l a t e a t 15-20  f l o e formed from a v i s u a l  The s a m p l e s  p o i n t of  w e r e t h e n s e t t l e d (0 rpm)  rpm  view.  and the s e t t l i n g  time  measured. The p r o c e d u r e  o u t l i n e d a b o v e was r e p e a t e d f o r s a m p l e s  spiked  to  2+ a n a l k a l i n i t y o f 200 mg/1  as  The pH s t a b i l i z a t i o n c u r v e s conclusions  of  this  series  CaCO^ a n d f o r Mg  d o s a g e s f r o m 0 t o 50  a r e p l o t t e d on F i g u r e of  tests  a r e as  22,  23 a n d 2 4 .  mg/1.  The  follows:  2+ i ) A t t h e n o r m a l a l k a l i n i t y o f t h e P P E , a n i n c r e a s e i n Mg d o e s n o t a p p e a r t o a f f e c t t h e pH s t a b i l i z a t i o n t i m e ( s e e F i g u r e 2 2 ) . ii) increases  At the elevated a l k a l i n i t y ,  t h e pH s t a b i l i z a t i o n t i m e ( s e e  an  increase  Figures  23 and  i n Mg  2+  dosage  dosage  24).  2+ iii) increase  Increased  a l k a l i n i t y a t a c o n s t a n t Mg  dosage does  not  t h e pH s t a b i l i z a t i o n t i m e ( s e e F i g u r e s 22 a n d 2 3 ) . i v ) A r a p i d m i x t i m e o f 15 m i n u t e s w o u l d s t a b i l i z e t h e pH  under  2+ all  conditions  (192 mg/1  as v)  point of  e x c e p t t h e c a s e o f h i g h Mg  ( 5 0 mg/1)  and h i g h  alkalinity  CaC0 ). 3  A f l o c c u l a t i o n t i m e o f 3 m i n u t e s was  adequate  from a  visual  view. vi)  The s a m p l e  The n e x t s e r i e s l a t i o n time.  It  was  felt  s e t t l e d i n 10-15 of  minutes.  t e s t s were performed  that although  to e s t a b l i s h  the f l o c c u -  t h e pH h a d s t a b i l i z e d a f t e r 15  minutes  0  5  10  15  20  Time (minutes ) i-  FIGURE22 pH Vs. T I M E F O R P P E AT N A T U R A L ALKALINITY(I30mg/I  CaC0 ). 3  1  12  No  Rapid x 10  Mg 2+  Mix  x — x  F l o e c u la t i o n  A — A  Settling  10  15  20  Ti m e ( m i n u t e s )  F I G U R E 2 3 pH Vs. T I M E F O R P P E A T E L E V A T E D A L K A L I N I T Y ( 2 0 0 m g / l  CaC0 ) 3  T  T  T 35mg/IMg  Time ( minutes )  FIGURE 24  pH Vs. T I M E  FOR P P E AT E L E V A T E D A L K A L I N I T Y * 192mg/1 as C a C 0 ) . 3  •74.  other  t r a c e m e t a l r e m o v a l mechanisms  ( i . e . entrapment,  complexation)  may  2+ require further reaction time.  To t e s t  this  theory, a s e r i e s  o f Zn  removal  t e s t s were performed i n which the o v e r a l l r e a c t i o n time ( r a p i d mix flocculation) arbitrarily  w e r e v a r i e d b e t w e e n 15 a n d 60 m i n u t e s .  chosen  as  the heavy m e t a l f o r the t e s t s .  Z i n c a t 5.0  plus mg/1  The t e s t was  was  performed  2+  a t t h e m i d d l e o f t h e pH r a n g e ( 1 0 . 6 ) a n d Mg d o s a g e o f 17 mg/1 was c h o s e n from p r e v i o u s t e s t work. The r e s u l t s o f t h e t e s t s a r e p l o t t e d i n F i g u r e 2 5 . 2+ The minimum t i m e r e q u i r e d t o r e d u c e t h e Zn a p p e a r e d t o b e 25 m i n u t e s . f l o c c u l a t i o n t i m e was  t h e r e f o r e adopted f o r a l l f u t u r e t e s t  p o i n t o f v i e w w i t h i n 15 m i n u t e s  15-20  minute  work.  s e t t l i n g was c o m p l e t e d f r o m a  therefore a s e t t l i n g time of  the i n i t i a l  t e s t w o r k a r a p i d m i x t i m e o f 100  a n d due t o t h e l o n g pH s t a b i l i z a t i o n t i m e s  of  range  visual  30 m i n u t e s  was  chosen.  In  that this  t o i t s minimum  A 15 m i n u t e r a p i d m i x t i m e a n d a 10  As p r e v i o u s l y m e n t i o n e d ,  arbitrarily  residual  speed w o u l d be s u i t a b l e  ± 5 rpm was  t h a t were d i s c o v e r e d  for future testing.  i t was  A flocculation  rpm was a d o p t e d on t h e r e c o m m e n d a t i o n o f R u s h ( 2 1 ) .  used felt speed  Settling  was  done a t 0 rpm. 3.  D o s a g e a n d M e t h o d o f Mg The g e n e r a l l y  ionic  form so  A series  2+  accepted theory  t h a t magnesium must be added i n  t h a t i t p r e c i p i t a t e s " i n s i t u " f o r o p t i m u m r e m o v a l was  o f e x p e r i m e n t s were performed u s i n g  o f MgSO^.7H 0 and M g ( 0 H ) . 2  removal i s rather  Addition  The r e s u l t s  2  o b t a i n e d when t h e c o a g u l a t i o n  t h a n l i m e and  l i m e and magnesium  a r e shown i n T a b l e 2 0 .  is  performed using  tested.  i n the The  its  form  best 2+  l i m e and Mg  Mg(0H) .  The m a g n e s i u m  2  was  4 t h e r e f o r e a d d e d i n t h e f o r m o f a 10 mg/1  Mg  2+  75.  0.6  [Zn  2 +  ] = 5 mg/1 i  [Mg  2 +  ] = 17 mg/1  LIME  = 2l6mg/l  Ul)  o> pH * " l b . 6  0.5  c o  SETTLING TIME = 30min  A—  o  +-  •c CP o co o  +  Zn  CM  0.4  o •3  <n CD  -  0.3  1 15 Overall  30 Reaction  45 T i m e (minutes)  60  F I G U R E 2 5 R E S I D U A L Z n C 0 N C E N T R A T I 0 N Vs. O V E R A L L REACTION TIME (RAPID MIX+FL0CCULATI0N ) 2 +  T A B L E 20  A c o m p a r i s o n o f Heavy M e t a l . R e m o v a l s L i m e a n d Mg(OH) and L i m e and Mg  % Removal Trace  Metal  Lime  Only  Using  (Unfiltered  L i m e and M g ( 0 H )  2  Data)  Limedand  Cr  92.7  95.6  96.6  Cu  54  57.1  70  Ni  56  56.3  57  Zn  79  86.2  90  Initial  Conditions  I n i t i a l m e t a l c o n c e n t r a t i o n 2.6 Lime Dosage  186 mg/1  2+ Mg  Dosage  17  mg/1  (average)  mg/1  (ap.prox)  Mg  2+  s o l u t i o n o f MgSO^.TH^O.  On t h e r e c o m m e n d a t i o n s  o f . R u s h . C21),  t h e Mg  a d d i t i o n was g i v e n a 1 m i n u t e r a p i d m i x t i m e i n o r d e r t o a c h i e v e prior 4.  to the lime a d d i t i o n .  Dosage and Method o f Initially,  slurry  the Lime A d d i t i o n  t h e l i m e a d d i t i o n was made u s i n g  of h i g h p u r i t y reagent grade Ca(0H)  was r e p l a c e d b y a d r y r e a g e n t Ca(QR)^  3 seconds  due t o s l u r r y  addition.  to s t i r  percent This  settling,  With the dry  Lime-Magnesium  the t e s t beaker f o r  about  Coagulation Test  Sequence  procedure t h a t would produce comparable r e s u l t s  coagulation  f o r the removal of  d i f f e r e n t heavy metals from m u n i c i p a l wastewater.  1)  the  surface.  The p r e l i m i n a r y t e s t w o r k was c a r r i e d o u t t o d e v e l o p a  consisted of  and  reagent  w i t h a glass rod immediately a f t e r the a d d i t i o n to prevent  Ca(0H)2 f r o m f l o a t i n g on t h e 5.  g r a d e Ca(OH)  a d d i t i o n i t was n e c e s s a r y  a 10 w e i g h t  i n d i s t i l l e d water.  2  p r o c e d u r e gave p o o r r e p r o d u c i b i l i t y , p r e s u m a b l y  grade  dispersal,  five  The d e t a i l e d t e s t  procedure  the f o l l o w i n g procedure: E v e r y Monday m o r n i n g d u r i n g  obtained from Annacis  t h e t e s t p e r i o d , a s a m p l e o f PPE  I s l a n d Sewage T r e a t m e n t P l a n t a n d s t o r e d i n t h e  was  3°C  incubator. 2) F o r e a c h r u n a s e t o f 1 l i t r e beakers  using  a 1 litre  7 -  600 m l s a m p l e s  graduated c y l i n d e r .  were measured out The s a m p l e s w e r e  warmed t o 20-21°C b y p l a c i n g them i n t h e 35°C i n c u b a t o r f o r a b o u t 1% 3)  The s a m p l e s w e r e t h e n s p i k e d t o t h e r e q u i r e d i n i t i a l  concentrations using 4)  the heavy m e t a l s p i k e  s p i k e d w i t h the a l k a l i n i t y s p i k e  solution.  then hours.  metal  solutions.  F o r r u n s done a t e l e v a t e d a l k a l i n i t y , t h e s a m p l e s  were  into  then  ion  78.  5) One of the samples was - set aside for i n i t i a l metal ion concent r a t i o n (s)  analysis. 6) One:of the samples was then used to calculate the lime dosage.  The sample was mixed at 100 rpm on a Phipps and Bird Laboratory s t i r r e r and the pH was constantly monitored to 10.0,  10.7 or 11.4.  The CaCOH^ r e q u i r e -  ment was calculated and f i v e doses were measured out. 7) The f i v e remaining samples were s t i r r e d on the laboratory s t i r r e r at 100 rpm for 1 minute to disperse the metal ion and the a l k a l i n i t y spike. 8) With the s t i r r e r off, the following additions of the Mg  2+  solution were pipetted into the samples: 0.5 ml, 1 ml, 2 ml and 3 ml.  These  2+ additions corresponded to 0, 8, 17, 33 and 50 mg/1 Mg  respectively.  9) The samples were s t i r r e d for 1 minute at 100 rpm and then the CaCOH^ addition was made. 10) The samples were then given a 15 minute rapid mix, a 10 minute f l o c c u l a t i o n and a 30 minute s e t t l e as previously discussed. 11) Since the f i n a l pH measurement and supernatant sampling took about 10 minutes, they were begun after 25 minutes s e t t l i n g . For a l l runs 2+ except those using Pb , two 50 ml samples were pipetted f-romreach beaker. To reduce contamination problems, the supernatant samples were taken i n order 2+ of decreasing Mg dosage.  2+ For the Pb runs, two 100 ml samples were  required as i t was necessary to concentrate them four times by b o i l i n g . 12) One of the two supernatant samples was f i l t e r e d through #2 Whatman f i l t e r paper. 13) The metal analysis was then performed by Atomic Absorption Spectroscopy as described i n Section 5.2.2. 14) The heavy metal percent removals were then calculated using  79.  the following formula: P ^ i  -  *  100  15) A completed data sheet i s shown i n Figure 26.  80.  O b j e c t : ' Cu @ 5 . 0 m g / 1 ; pH  R u n #:  Eloc  1  Cu  Date:  20 J u l y  Lime Dosage: pH  Mg  I n i t i a l wt  -  1.0376  1  10.70  0  F i n a l wt  .9094  2  10.70  8  Addition  .1282  3  10.65  17  4  10.60  33  5  10.54  Start:  Remarks: Cu  50  2 +  spike  S a m p l e #12  1:14  A-A A n a l y s i s : Sample  ABS  1976  2 +  test:  Beaker  - 2.9  ml  - Acids only i n d i s t i l l e d water 2+  (810) Cone  Removal  1 2 3 4 5  f  1.85 1.35 1.25 "...90 .85  63 73 75 82 83  1 2 3 4 5  unf  1.70 1.30 1.10 .85 .80  66 74 78 83 84  #6 #12  10.7  S a m p l e #6  - Initial  Cu  Alkalinity  - 120-130  mg/1  5.0 ^0  F i g u r e 26:  Comple  d Data  Sheet  81.  APPENDIX B COMPARISON OF E F F E C T I V E N E S S AND COSTS OF HIGH L I M E TREATMENT ( H . L . ) INTERMEDIATE L I M E / M g  2 +  TREATMENT  vs (I.L./Mg  2 +  )  Basis: .(1)  Comparison 2.5 mg/1  b a s e d on a 10 mgd p l a n t w i t h w a s t e w a t e r  of  Cr  3+  , Cu  2+  , Pb  2+  and Zn  2+  .  containing  N i c k e l has been  eliminated  2+ becauxe  I.L./Mg  process  for  (2)  this  Supernatants  of  would not be c o n s i d e r e d  a possible  treatment  metal. the f o l l o w i n g q u a l i t y w o u l d be o b t a i n e d  c h e m i c a l dosages shown. for municipal  as  The A - A  type wastewaters H.L.  treatment  (400 mg/1  a n d B-B  i n B.C.  2  Pollution Control  the objectives  h a v e b e e n shown f o r  I.L./Mg  Ca(0H) )  for  2+  treatment  comparison. A-A  B-B  220 mg/1 Ca(OH) 33 mg/1 M g 2 +  Cr  3 +  .06  .10  .1  .3  Cu  2 +  .38  .59  .2  .5  .21  .14  .05  .10  .26  .19  .5  Pb r,  Zn  (3)  2+  A s s u m e 90% Mg l i m e due  (4)  Assume it will  2+  to heavy m e t a l  that i f  and r e c y c l e  recovery  for  of the  contamination.  filtration  be r e q u i r e d  (Rush) and z e r o r e c y c l e  5.0  is required  both processes.  (and  this  i s very  l i k e l y ) , that  Treatment  Comparison: ^~~~~^~-£rocess  H.L.  I.L./Mg  2 +  Parameters R e a c t i o n pH  11.4  Sludge Volume (minus i m p u r i t i e s )  400 mg/1  Chlorination requirement  possibly not  Chemical c o s t s * (per day)  $1200  (lime)  10.6  223 mg/1  yes  $675 ( l i m e ) $100 ( M g ) $775 Z +  Costs not estimated  a) for b) for  excess r e c a r b o n a t i o n costs H1L. t r e a t m e n t . excess sludge handling costs H.L. t r e a t m e n t . 2+  Miscellaneous  sludge s e t t l i n g f o r may b e a p r o b l e m  Dow C h e m i c a l - M g C l Domtar  + =  2  @ $8.20/cwt  I.L./Mg  (bulk)  - L i m e @ $ 6 2 . 5 0 / t o n (22 t o n l o t s )  The above c o m p a r i s o n i n d i c a t e s t h a t I.L./Mg  treatment might  be b e c h e a p e r when t r e a t i n g i d e n t i c a l w a s t e s t r e a m s t o s i m i l a r quality.  supernatant  

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