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Color removal from kraft mill effluents by a coagulation-flotation process Wood, Arnaldo Hugo 1974

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COLOR REMOVAL FROM KRAFT HILL EFFLUENTS BY A COAGULATION-FLOTATION PROCESS by ARNALDO HUGO WOOD B.A.Sc.,  Universidad  de O r i e n t e ,  1963  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER APPLIED  in  the  SCIENCE  Department of  CHEMICAL  We  accept  required  this  thesis  ENGINEERING  as c o n f o r m i n g  to the  standard  THE UNIVERSITY OF BRITISH COLUMBIA September,  197 * 1  In  presenting  an  advanced  the I  Library  further  for  degree shall  agree  scholarly  by  his  of  this  written  this  thesis  in  at  University  the  make  that  it  purposes  for  may  be  It  financial  of  of  Columbia,  British  available for  by  the  understood  gain  of  CHEMICAL  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8. Canada  shall  SEPTEMBER  I 97^  the  Head  be  requirements  reference copying  that  not  ENGINEERING  Columbia  for  extensive  granted  is  fulfilment  permission.  Department  Date  freely  permission  representatives. thesis  partial  of  agree  and  of my  I  this  or  allowed  without  that  study. thesis  Department  copying  for  or  publication my  A B S T R A C T  evaluated  The  technique  for  the  effluents.  The  colloidal  of  removal  process  chromophores  coagulation-flotation of  was  tation  agent.  and  carried  the  range  100-200 to  obtained  were  at  pH of  in  expressing  be  developed.  the  in  during  several  effect  of  c e l l .  of  surfactant  and  An  factors.  100  ppm  removed  process  of  was  the  behaviour  The  The  best  the  on  Variables  the such  color as  be  •  were the  reliable had  and  to  mill  content  of  the  i n i t i a l waste  sequences;  time,  over  shown  results  pHs  kraft  solids  premixing  i i  was  f 1oa.tabrl i t y  different  and  pH  from  approach  a c i d i f i c a t i o n - a l k a l i z a t i o n  storage  of  designed  Since  to  f l o -  were  effects  not  the  the  and  concentrations  a)  of  of  coagulant  another  at  mill  experiments  proven  embraced:  solution  a  surfactant.  result,  kraft  surfactant  interaction  two  studies  b)  as  flotation  from  been  coagulation  cationic  batch  aqueous  concentrations;  upon  of  these  color  bodies  bromide)  sets  and  3.6  Other surfactant  a  a  investigated.  between  percentage  effluent.  in  3.6-5.6  ppm  exist  Several  out  based  using  (didodecyldimethylammoniurn  color  has  of  s t i r r e r  c)  the the  speed,  air  flow rate,  and  temperature  sparger  were b r i e f l y  Laboratory and  size,  stage  The  results  in  b a t c h and  inspected.  scale continuous  r u n a t t h e optimum b a t c h  premixing  i n t r o d u c t i o n of the s u r f a c t a n t  t u r n e d out  conditions.  t o be  essential  were c o m p a r a b l e t o t h o s e hence the p o s s i b i l i t y  coagulation-flotation  e q u i p m e n t was  p r o c e s s was  i ii  The  assembled  presence  f o r the  of a  process.  previously obtained  of developing establ ished.  a  continuous  TABLE OF CONTENTS  Page ABSTRACT  i i  L I S T OF TABLES  v i i  L I S T OF FIGURES  viii  ACKNOWLEDGEMENTS  x  INTRODUCTION  1 .  Chapter 1  BACKGROUND INFORMATION 1.1 1.2 1.3 1.4  1.5  4  The C o l o r B o d i e s i n K r a f t M i l l Effluents: A Potential Pollutant Removal o f C o l o r f r o m Mill Effluents Essentials Separation  4  Kraft  o f A d s o r p t i v e Bubble Techniques (22)  10 14  M i c e l l e F o r m a t i o n and C r i t i c a l M i c e l l e C o n c e n t r a t i o n i n Aqueous Solutions of Surfactants  17  A Word o f C a u t i o n C o n c e r n i n g t h e D e s i g n and A n a l y s i s o f F l o t a t i o n Experiments (46)  20  iv  Chapter 2  3  4  Page OBJECTIVES OF THIS WORK  22  2.1  Batch  23  2.2  Continuous  24 25  3.1  Batch  25  3.2  Continuous Studies  Studies  RESULTS AND DISCUSSION  4.2 4.3  4.4  4.5  5.2 5.3  31 36  S t u d i e s on t h e F l o a t a b i l i t y o f Pure S u r f a c t a n t  36  Studies Applied  44  o f the F l o t a t i o n Process t o K r a f t M i l l Waste  S t u d i e s on t h e I n f l u e n c e o f pH A d j u s t m e n t and Time E l a p s e d on t h e K r a f t M i l l Waste  61  S t u d i e s on t h e B e h a v i o r o f K r a f t M i l l Waste i n V a r i o u s A c i d i f i c a t i o n A l k a l i z a t i o n Sequences  66  Other V a r i a b l e s o f I n t e r e s t  72  CONCLUSIONS 5.1  6  Experiments  EXPERIMENTAL  4.1  5  Experiments  74  From t h e S t u d i e s on t h e F l o a t a b i l i t y of the S u r f a c t a n t  74  From t h e S t u d i e s Process  on t h e F l o t a t i o n 75  From t h e S t u d i e s  on t h e E f f l u e n t  Behavior  77  FURTHER WORK  79  REFERENCES  81  v  Appendices A  B  C  D  E  Page A n a l y s i s of Variance of the Designed Set of Batch Experiments Regression Analysis Applied D a t a O b t a i n e d a t pH 3.6 A n a l y t i c a l Techniques Cleaning Procedure  87 to the 108  and 127  F l o t a t i o n of K r a f t M i l l Effluent. Tabulated Batch Experimental Results  133  B i b l i o g r a p h i c Survey M e t h o d s f o r Removing Kraft Mill Effluents  136  vi  on P r o p o s e d C o l o r From  LIST OF TABLES  Tab! e 1'  2  3  4  5  Page T h e o r e t i c a l Estimations of Percentage of L i g h t T r a n s m i s s i o n a t V a r i o u s Depths o f Water w i t h V a r i o u s C o n c e n t r a t i o n s o f C o l o r , 580 mu  8  Schematic C l a s s i f i c a t i o n of the A d s o r p t i v e Bubble Separation Techniques  15  Experimental Experiments  27  R e s u l t s from the F a c t o r i a l  Experimental Results Obtained f o r Di d o d e c y l d i m e t h y l ammoni urn Bromi de a t pH 4.6 and 25°C  42  Continuous Experiment R e s u l t s Obtained a t pH 3.6, 100 ppm o f S u r f a c t a n t and V a r i o u s R e t e n t i o n Times  60  vi i  LIST OF FIGURES  Figure 1  2  3  Page Absorbance versus wavelength f o r v a r i o u s c o n c e n t r a t i o n s of f i r s t c a u s t i c e x t r a c tion stage e f f l u e n t Schematic diagram of the apparatus i n the batch experiments  7  used 28  Schematic diagram of the f l o t a t i o n a p p a r a t u s used i n the c o n t i n u o u s experiments .  32  4  Flotation  of s u r f a c t a n t i n water  37  5  Flotation  of s u r f a c t a n t i n water.  6  F l o t a t i o n of s u r f a c t a n t i n k r a f t mill effluent  7  8  9  10  . . . . . . . .  R a t i o of s o l i d s f l o a t e d to s u r f a c t a n t floated in kraft mill effluent F l o t a t i o n of s o l i d s mill effluent  from  F l o t a t i o n of s o l i d s mill effluent  from  C o l o r v e r s u s pH effluent  40  47  .  48  kraft 49 kraft 49  for total  mill 56  vi i i  Figure 11  12  13  14  15  16  17  Page E f f e c t o f s t o r a g e t i m e and pH on s o l i d s content of kraft m i l l effluent  62  E f f e c t o f s t o r a g e t i m e and pH on color of kraft mill effluent  63  E f f e c t o f s t o r a g e on a b s o r b a n c e ( a t pH 7.6) o f u n t r e a t e d w a s t e  64  C o l o r removal from k r a f t m i l l e f f l u e n t as a f u n c t i o n o f amount o f s u r f a c t a n t added and pH  67  Behaviour of k r a f t m i l l e f f l u e n t i n t h e s e q u e n c e acidification«alkalization* acidification  69  Behaviour of k r a f t m i l l e f f l u e n t i n the sequence a l k a l i z a t i o n - a c i d i f i c a t i o n • alkalization«acidification  70  A c i d i f i c a t i o n of kraft caustic e x t r a c t i o n e f f l u e n t w i t h 98% HaSO.,  71  ix  ACKNOWLEDGEMENTS  The  author  for  h i s support  for  remaining  failed. of  Pinder. Leja  Julien  Many  from  the  shown  by o t h e r  members  work  Engineering  Engineering  from  the Faculty  appreciated  performed  were  of  regarding  this  to Dr.  held  with  Dr.  and Dr.  Forestry.  i s the assistance  by t h e s t a f f  else  the Faculty  Department of  Branion  everybody  particularly  discussions  M.  and e s p e c i a l l y  Department  acknowledged,  valuable  Demaerschalk  research, when  the Mineral  Highly  i n this  :  Dr. Richard  at times  Chemical  i s sincerely  to thank  friend  The i n t e r e s t  project  Jan  and advice  a true  the U.B.C.  K.L.  wishes  '  of t h e workshop  offered of  and  t h e same  department. The students dull  author  f o r their  helpful  concern  are also  to his fellow  suggestions  graduate  received  during  sharing  due t o E n g . Don H e r s c h m i l l e r  and cooperation  Finally, for  most  indebted  hours. Thanks  his  feels  with  during  gratitude  me e v e r y  step  the experimental  i s expressed of  x  the  way.  t o my w i f e ,  f o r  work. Miriam  I N T R O D U C T I O N  In into  r e c e n t y e a r s the c o l o r of e f f l u e n t s d i s c h a r g e d  receiving  mental  waters  problem.  has  emerged as an  In a d d i t i o n  to the a e s t h e t i c  been s u g g e s t e d t h a t t h e c o l o r may  be p a r t l y  responsible  biological  marine  of  p h y t o p l a n k t o n i c organisms  communities  pollutants  is inhibited  effluents  in kraft mill  e x t r a c t i v e s , and It  (1) because  the b y - p r o d u c t s of the p u l p i n g  The  i s believed  lignin ture  and  (2).  effluent  into  these waters of the  the  by t h e  structure  development reduced  sunlight.  K r a f t pulp m i l l of  introduced  a s p e c t s , i t has  f o r the d e t e r i o r a t i o n  of  p e n e t r a t i o n of  important environ-  lignin  and  waste  are complex m i x t u r e s  and  bleaching processes.  water are p r i m a r i l y  cellulose  degradation products.  t h a t the c o l o r e d m a t e r i a l s  lignin  orginate  f r a g m e n t s w h i c h have a q u i n o n e  T h e s e compounds i m p a r t a brown c o l o r  c a u s i n g the r e c e i v i n g  waters  wood  to t u r n  from  type  struc-  to the  the c o l o r  of  dark t e a . Present treatment processes f o r kraft m i l l are  primarily  devoted  to the removal  1  o f BOD.  wastes  These p r o c e s s e s  2  such not  as t h e a c t i v a t e d  sludge process  have much e f f e c t on c o l o r , p r o b a b l y  associated with l i g n i n microbiological  waters.  for color  A variety removal  carbonate  filtration,  or activated  liquid-liquid  lime treatment  process  l a g o o n s do  because c o l o r i s  m a t e r i a l s which  These i n c l u d e t r e a t m e n t  calcium  by  like  degradation.  been been p r o p o s e d  are r e s i s t a n t to  of processes  from  have  kraft mill  waste  w i t h l i m e , a d s o r p t i o n on  carbon,  reverse  osmosis,  e x t r a c t i o n , and f l o t a t i o n .  The  a t p r e s e n t seems t o be t h e one f a v o r e d  industry. The  treatment in  or aerated  South  processes Africa  America  (3).  removal  from  (4). tively using  flotation  process  and i n t h e t r e a t m e n t  i n water  o f paper  and Sweden b u t has been l i t t l e  An i o n f l o t a t i o n kraft mill  This process charged  has been used  process  waste water  i s based  used  specific  i n North  f o r color  was d e v e l o p e d  by H e r s c h m i l l e r  chromophores  s u r f a c e a c t i v e agent  (the  of  a i r bubbles.  color  i s floated  At the surface a f r o t h  showed t h e f e a s i b i l i t y  batch, laboratory scale.  The complex  t o t h e s u r f a c e by t h e i n t r o d u c t i o n  i s f o r m e d and c a n be e a s i l y  obtained  colligend)  (the c o l l e c t o r ) .  product of the c o a g u l a t i o n r e a c t i o n , a surface a c t i v e c a l l e d sublate  wastes  on t h e c o a g u l a t i o n o f t h e n e g a -  soluble or c o l l o i d a l  a cationic  mill  c o n t a i n i n g most o f t h e  removed.  The r e s u l t s  of the process  a t l e a s t on a  3  The  purpose  of the p r e s e n t i n v e s t i g a t i o n  e x p a n d upon t h e r e s u l t s  of H e r s c h m i l l e r  of  color  any  certain  variables  interaction  effects  sense, to develop tiveness on  criterion  o f t h e p r o c e s s , and  useful  economic  removal,  t o see  between v a r i a b l e s  a better  a continuous basis.  s h o u l d be its  on  i n terms  The  suitability.  of the  information  effects  statistical the  to t r y out the t h u s made  t h e p r o c e s s and  to  i f t h e r e were  f o r evaluating  to a t t e m p t  in optimizing  in a  was  effecprocess  available  in determining  Chapter 1  BACKGROUND INFORMATION  1.1  The A  Color  Potential The  presence of by  the  tion the  Bodies  in Kraft Mill  Pollutant  color  of  the  soluble  or  colloidal  pulping  and  tion  kraft mill  wastes r e s u l t s from  c o m p o n e n t s o f wood as  bleaching  operations.  During  s t a g e of a c o n v e n t i o n a l  k r a f t pulp  bleaching  color-producing  compounds a r e  m o s t l y removed i n t h e The  Effluents:  subsequent c a u s t i c  waste w a t e r from the stage c o n s t i t u t e s  effluent  the  greatest  chlorina-  sequence,  soluble  and  extraction  pulp washers of  the  are  stage.  caustic  source of  modified  color  extracin  the  (5). Lignin  f o r most o f  the  and/or i t s d e g r a d a t i o n color  of  the  effluent  siderable  amount o f work w h i c h  intention  of  responsible resolved.  rendered  the  the  i d e n t i f y i n g the f o r c o l o r , the  According  has  to Hayes and  4  (2).  responsible  D e s p i t e the  been p e r f o r m e d w i t h  specific  matter  products are  has  conthe  chromophoric  groups  not  completely  Munroe  yet (3),  been  5  . . . t h e d a r k c o l o r in k r a f t m i l l effluent o r i g i n a t e s in d o u b l e bonds c o n j u g a t e d w i t h aromatic r i n g s , chalcones, quinoid s t r u c t u r e s , f r e e r a d i c a l s , m e t a l l i c complexes ( 6 ) , a l k a l i n e d e g r a d a t i o n p r o d u c t s of s u g a r and chlorinated lignin derivatives (7). Much of t h e c o l o r is in t h e form of c o l l o i d a l pa r t i c I e s (8 ) . Known t o x i c i m p u r i t i e s a r e a l s o p r e s e n t in the e f f l u e n t : resin acids, fatty acids, i n o r g a n i c and o r g a n i c s u l f i d e s , t e t r a c h I o r o o - b e n z o q u i n o n e and 4 - p - t o I y I - I - p e n t a n o I (9). C e r t a i n of t h e s e c o m p o u n d s , e . g . r e s i n a c i d s , f a t t y a c i d s and l i g n i n a r e s u r f a c e a c t i v e , hence p a r t l y r e s p o n s i b l e f o r t h e g e n e r a t i o n o f foam.  All  the published  large  charged  the techniques  from  colloids" suggested  t h e e f f l u e n t s a r e based The  mentioned  agrees  t h a t "a  provide  to any a q u a t i c effluent  of the c o l o r  on t h a t f e a t u r e  fraction  (Appendix E ) .  against  receiving waters, criticism By  y e t observed  - at least,  But, although dumping  a t normal  no c o n c l u s i v e  reasons  highly colored effluents  on t h e f o l l o w i n g  might:  s y n t h e t i c  toxic  the c o l o r of e f f l u e n t i s meeting  reducing  c o l o r and  unaffected  T h e s e compounds have n o t been f o u n d  concentrations.  1.  f o r removal  The m a j o r i t y  most o f t h e c o l o r , a r e l a r g e l y  species  have been g i v e n  increased  (3,4,10,11,12,13).  1 i g n i n - r e l a t e d components o f t h e w a s t e , which as  by b i o - o x i d a t i o n .  into  on t h e s u b j e c t  p o r t i o n o f t h e p o l l u t a n t s b e h a v e as s t r o n g l y h y d r o p h i l i c ,  negatively of  material  s u n l i g h t a)  p e n e t r a t i o n ,  i n h i b i t  a c t i v i t i e s  microorganisms  grounds:  o f  t h e  a q u a t i c  thereby  t h e  photop l a n t s  causing  an  6  upset i n the ecology of that p a r t i c u l a r b o d y o f w a t e r ( 1 ^ , 1 5 ) ; b) a f f e c t t h e g r a z i n g h a b i t s o f z o o p l a n k t o n and o t h e r m a r i n e o r g a n i s m s w h i c h depend upon s i g h t f o r discriminatory feeding (16). 2.  The c o l o r e d c o m p o n e n t s m i g h t be t o x i c t o some o f t h e l o w e r s c a l e o f o r g a n i s m s in the a q u a t i c eco-system.  3.  A t some d o w n s t r e a m p o i n t , t h e c o l o r e d w a t e r may b e c o m e p a r t o f a m u n i c i p a l water supply, where c o l o r removal might be t r o u b 1 e s o m e .  k.  Esthetica11y, strong color i s inconsistent with present public a t t i t u d e s .  Several absorption  attempts  values  of k r a f t mill  been f u l l y s u c c e s s f u l standard  and  specifically  method more d i r e c t l y  Herschmi11er caustic  (4) s t u d i e d  because o f the l a c k of a a p p l i c a b l e to the e f f l u e n t s .  t h e changes i n absorbance o f f i r s t  concerning  ( 1 5 ) has p u b l i s h e d  t h e o r e t i c a l estimates  to d i f f e r e n t color concentrations  (Table  1).  concentrations  (Figure 1).  B.C. R e s e a r c h  due  light  e f f l u e n t s , t h e s e have n o t y e t  e x t r a c t i o n stage e f f l u e n t a t d i f f e r e n t  wavelengths  results  have been made t o e s t i m a t e  From t h e i r  highly interesting  of l i g h t  depletion  in kraft mill  r e s u l t s i t i s obvious that  effluents differences  in c o l o r values  as s m a l l  the  of l i g h t .  Since  on v i s i b l e  r a d i a t i o n , the e x t i n c t i o n of  penetration  depend e n t i r e l y would c o r r e s p o n d  as 10 u n i t s c a n d r a m a t i c a l l y photosynthetic  activities  to e l i m i n a t i o n of primary p r o d u c t i o n  c o n s e q u e n t l y , of a l l t h e dependent a q u a t i c  life.  reduce  light  and  7  figure  1.  A B S O R B A N C E VERSUS WAVELENGTH FOR V A R I O U S C O N C E N T R A T I O N S OF FIRST CAUSTIC EXTRACTION STAGE EFFLUENT  wavelength  (nanometers)  Table 1 Theoretical  Estimations of Percentage c f L i g h t Transmission of Water w i t h V a r i o u s C o n c e n t r a t i o n s  Depths  PERCENT TRANSMISSION AT VARIOUS COLOR UNITS  Depths  On)  at Various  o f C o l o r , 580 mu  1  2  3  4  5  6  7  8  9  10  15  20  25  30  35  40  45  50  1  97.1  94 .2  91 .4  88.7  86.1  83.6  81.1  78.7  76.4  74.2  63.8  55.0  47.3  40.8  35.1  30.2  26.0  22.4  2  94.2  83.7  83.6  78.7  74.2  69.9  65.8  61 .9  58.4  55.0  40.8  30.2  22.4  16.6  12.4  9.1  6.8  5.0  3  91.4  83.5  76.4  69.9  63.8  53.4  53.3  48.7  44.6  40.8  26.0  16.6  10.6  6.8  4.3  2.8  1 .8  1.1  **  88.7  78.7  69.9  61 .9  55.0  43. 7  43.2  38.4  34.1  30.2  16.6  9.1  5.0  2.8  1.5  5  SS.l  74.2  63.9  55.0  47.3  40.8  35.1  30.2  26.0  22.4  10.6  5.0  2.4  1.1  6  83.5  69.9  58.4  48.7  40.8  34.1  28.5  23.8  19.9  16.6  6.8  2.8  1.1  7  81 .1  65.8 ' 53.3  43.2  35.1  28.5  23.1  18.7  15.2  12.4  4.3  1.5  3  73.7  61.9  43.7  38.4  30.2  23.8  18.7  14.7  11.5  9.1  2.8  9  76.4  58.4  44.6  34.1  26.0  19.9  15.2  11.5  8.9  6.8  1 .8  10  74.2  55.0  40.8  30.2  22.4  16.6  12.4  9.1  6.8  5.0  1.1  11  71 .9  58.8  37.3  26.8  19.3  13.9  10.0  7.2  5.2  3.7  12  59.8  43.7  34.1  23.8  16.6  11.5  8.1  5.7  3.9  2.8  13  67.8  45.9  31 .1  21.1  14.3  9.7  6.6  4.5  3.0  2.1  14  55.8  43.2  28.5  18.7  12.4  8.1  5.3  3.5  2.3  1.5  15  63.3  40.8  26.0  16.6  10.6  6.8  4.3  2.8  1 .8  1.1  15  52.0  33.4  23.8  14.7  9.1  5.7  3.5  2.2  1 .3  17  60.1  36.2  21 .7  13.1  7.9  4.7  2.8  1.7  1 .0  18  53.4  34.1  19.9  11.5  6.8  3.9  2.3  1.3  19  55.6  32.1  18.1  10.3  5.8  3.3  1.9  1.0  20  55.0  30.2  16.6  9.1  5.0  2.8  1 .5  21  53.4  28.5  15.1  8.1  4.3  2.3  22  51.8  25.8  12.0  7.2  3.7  1 .9  23  50.2  25.2  12.6  6.4  3.2  1.6  CONTINUED  Table  Depth (m)  1  (Continued)  PERCENT TRANSMISSION AT VARIOUS COLOR UNITS 1  2  3  4  5  5  24  43.8  23.8  11.5  5.7  2.8  1.3  25  47.3  22.4  10.6  5.0  2.4  1.1  30  40.8  16.6  6.8  2.8  1.1  35  35.1  12.4  4.3  1.5  40  30. 2  9.1  2.8  45  25.0  6.8-  1 .8  50  22.4  5.0  1.1  60  16.6  2.8  70  12.4  1.5  80  9.1  90  6.8  100  5.0  110  3.7  120  2.8  130  2.1  7  |  8  9  10  15  20  25  30  35  40  45  50  10  1.2  Removal  of C o l o r from  Kraft Mill  Effluents  T h e r e have been numerous t e c h n i q u e s color  removal  from  methods t h e b e s t are:  a)  waste waters  toward  removal  techniques.  techniques  will  ( 1 8 ) and  Hutchinson  the n a t u r a l foaming  to  remove c e r t a i n The (21)  viable  kraft  process  activated  carbon,  ultrafiltration. to c o l o r  removal E. work  o f t h e w a s t e s by a p p l y i n g  i n 1958,  flotation  section. f o l l o w e d by  (19,20), p o i n t e d out a d v a n t a g e was  of k r a f t m i l l  undesirable constitutents  indicated  the l i g n i n  removing  (17)  tendency  experimental  these  only with previous  i n the next  developments i n which  of  Of  main f e a t u r e s o f t h e s e  several other authors  interesting  Miller  The  for  i s summarized i n Appendix  of the c o l o r  be o u t l i n e d  First  work p e r f o r m e d  Waldichuk very  being  taken  effluents  from  the  by W a r n e r  wastes. and  t h a t i t i s p o s s i b l e t o remove 18 t o  d i s p e r s e d i n water  by means o f foam  a c o n s i d e r a b l e amount o f t h e c o l o r  37%  thus  present  i n the  effluent. Of  of  more r e c e n t l y  present d i s c u s s i o n i s concerned  flotation  and  f o r a commercially  t e c h n i q u e s , and  kraft mill  directed  of  effluents.  bulk of a l l the p u b l i s h e d m a t e r i a l r e l a t e d  from The  prospects  paper m i l l  l i m e c o a g u l a t i o n , b) a d s o r p t i o n on  c) f l o t a t i o n The  p u l p and  proposed  Wang (12) color  special  interest  i n 1970.  i s a p a p e r p u b l i s h e d by  T h e i r work c o m p a r e d t h e  removed, i n terms o f l i g n i n  Wilson  percentage  c o n c e n t r a t i o n , achieved  11  by  two  different  and  ion  pH,  surfactant  flotation.  tration to  were  prove  method  flotation  dosage,  also  the  for  The  effects  studied.  removal  Recently  Das  Ca  a  below-the  pH  cations  Mg  ,  reacted  colloids  render a  dry  with  the  the  by  Instead,  stantially color  strongly  to  kraft  the  cationic  up  noted  at  dosage,  that  the  cationic  which  between  floated  and  4  without  of  the  extent  of  70%  T0C  (total  organic  carbon),  100%  turbidity  could  and  added  by  not  it -  67%  be  COD 42%  as to  treating  successful. alone,  a  of  to  remove  at  sub-  the  hydrophobic  aeration.  dosage  color,  The  reacting, with  to  88%  at  chromophoric  objective  forming  any  amine  was to  amine  reduction  demand  optimum  was  that  oxygen  an  capable 3  the  indicated  demand),  at  was  effluent  flotation)  ppm  a  gelatinous  hence  500  dosage, pHs  air  of  cations,  charged  amine  Nevertheless,  (dispersed  to  and  a  precipitation.  negatively  hydrophobic  was  as  multivalent  sufficient  flotation.  result  F i r s t ,  hydroxide  concen-  p o s s i b i l i t i e s  Next,  lower  precipitate  the  as  f l o t a t i o n .  hydrophilic,  was  bodies  ion  insoluble,  even  i t  to  such  solids  striking  an  precipitate  amine,  their  the  precipitate  scum  float  with  forming  precipitate.  of  added  factors',  fractionation  explored  were  level  foam  process.  fractionation  suspended  most  opposed  (11)  Al  of  foam  different  and  Their  as  precipitation-flotation i.e.  of  dissolved  ineffectiveness  color  ,  techniques:  The  300  ppm,  results ^pollution  (chemical BOD  oxygen  (biochemical  obtained.  12  The a new  work r e p o r t e d  approach to the  experiments. from  alum, v a r i o u s  The  dosage of  and  the  the  explain  as  trend  followed  removal  adding,  each f l o c c u l a n t - a i d from  5.5  to  10.0.  The  flocculant concentration p l o t s , although  I t was the  the  the  was  o f 90%  i n c o l o r , 50%  i n BOD  Herschmiller  runs  Division,  liter  adjusted  and  i t was  66%  Sc.  Canadian  to  22°C, and  i n each r u n .  The  The  The  interaction from  attempt  to  time  increased.  calgo'n  The  WT-2600. air flotation of  that a  the decrease  occurred. the  s u b j e c t was He  flotation Products  cell.  Limited,  amount o f w a s t e used  per  cent  carried  performed  temperature of  collector  didodecyldimethylammoniurn bromide.  ppm  flotation  thesis (4).  the  to 3  separation  i n COD  Forest  effluent.  0.5  claimed  in a rather simple  combined  of  pHs.  a dispersed  work done on  i n h i s M.A.  w a s t e w a t e r u s e d was  2.5  and  was  minutes with  studies  most e x t e n s i v e  a s e r i e s of batch  was  5-6  faster formation  In t h e i r m i n i p l a n t  e f f l u e n t was  amount  made no  dosage of f l o c c u l a n t - a i d  floe.  Mellon  bodies  became e v i d e n t  a l s o e s t a b l i s h e d t h a t the  obtained  system because of  The  flotation  presence of  authors  e x p e r i m e n t s were p e r f o r m e d w i t h  by  color  ranged from  All  out  represented  of s e l e c t e d c a t i o n i c , s y n t h e t i c ,  value  The  of  (3)  in ion  to a f i x e d  highest the  Munroe  weight p o l y e l e c t r o l y t e s at d i f f e r e n t  and  i t .  decreased  e f f l u e n t s by  values  resulting  Hayes and  the  concentrations  high molecular  b e t w e e n pH  general  They e v a l u a t e d  kraft mill  pH  by  the used  was of  color  Port  13  removed and o f s o l i d s f l o a t e d w e r e e v a l u a t e d u n d e r d i f f e r e n t values of the f o l l o w i n g d o s a g e , i i ) pH, i i i ) bubble  size,  parameters:  i ) surfactant  sparger porosity  and h e n c e ,  i v ) surfactant  vi) colligend-col1ector interaction his  batch  found  ratio.  between such  time, v) a i r sparge  rate,  However, t h e p o s s i b i l i t y  r e c o v e r y and c o l o r  o f 9 5 % a t optimum c o n d i t i o n s ;  of the t h i r d  indirectly,  o f any  f a c t o r s , was n o t i n v e s t i g a t e d .  results, flotation  i n excess  flotation  premix  or c o l l e c t o r  In  removal  also  were  precipitate  t y p e was p o i n t e d o u t as t h e p r i n c i p a l  mechanism o f t h e p r o c e s s . F u r t h e r r e s e a r c h based carried  o u t by Chan et  experiments. found  that  effective dicoco Inc.,  al.  (10) i n another  They s c r e e n e d  quaternary commercial  on H e r s c h m i 1 1 e r  s e t of batch  ammonium s a l t s w o r k e d b e s t . one f o u n d  Kanakee, I l l i n o i s ) .  was A l i q u a t  They a l s o  an optimum d o s a g e o f s u r f a c t a n t was  exceeded the t r e a t e d  The  b e s t pH r a n g e  by G e n e r a l noticed  ( 5 0 0 ppm).  kraft mill  The most  221 ( d i m e t h y l  that  Mills  Chemicals  t h e r e was  I f this  optimum  e f f l u e n t became c l o u d y o r t u r b i d .  was f o u n d  t o be 3.0 t o 5.0.  A total  decrease  and 8 0 % i n f l o a t a b l e s o l i d s was c l a i m e d .  Up t o t h e p r e s e n t t h e i o n f l o t a t i o n n o t been a p p l i e d  s t h e s i s was  a w i d e v a r i e t y o f s u r f a c t a n t s and  ammonium c h l o r i d e m a n u f a c t u r e d  of 95% i n c o l o r  1  commercially  wastes.  to the removal  p r o c e s s has of color  from  14  1 .3  E s s e n t i a l s of Adsorptive Adsorptive  differences molecular, tively through  i n surface a c t i v i t y .  which  made e f f e c t i v e l y to  and i s t h e r e b y  concentrated  s u r f a c e a c t i v e through  a oolligend  union  The s u b s t a n c e  cation  techniques.  proposed  Table et  by K a r g e r  2 shows al.  methods) are d i v i d e d u n e q u a l l y larger, called foam o r f r o t h termed  smaller division  with or adherence so removed i s  into  adsorptive  bubble  classifi-  These t e c h n i q u e s  two m a i n g r o u p s :  (or  the of a  The s m a l l e r , w h i c h i s  is further divided.  Bubble  by b u b b l e adsorption o r a t t a c h m e n t , f o l l o w e d by d e p o s i t i o n  an i m m i s c i b l e l i q u i d  the  be  (25) i s the t r a n s f e r o f m a t e r i a l w i t h i n a  i s the s i m i l a r  larger  can o f t e n  t h e scheme o f  (24).  to c a r r y o f f m a t e r i a l .  the top of the l i q u i d  (23)  separated.  nonfoaming a d s o r p t i v e b u b b l e s e p a r a t i o n , does n o t .  fractionation  at  rising  foam s e p a r a t i o n , r e q u i r e s t h e g e n e r a t i o n  This  liquid  i s selec-  (23).  T h e r e a r e a number o f i n d i v i d u a l separation  or  on  be  of bubbles  i s not s u r f a c e a c t i v e i t s e l f  a s u r f a c e a c t i v e collector.  termed  in size,  at the s u r f a c e s  (22)  a r e based  M a t e r i a l , w h i c h may  or m a c r o p a r t i c u l a t e  adsorbed or a t t a c h e d a liquid,  Techniques  bubble s e p a r a t i o n techniques  colloidal,  A substance  Bubble Separation  division  foaming  as t h e b u b b l e s e x i t .  t r a n s f e r t o , or to e i t h e r placed  Solvent s u b l a t i o n interface of,  on t o p o f t h e m a i n l i q u i d .  i s also subdivided.  The  Foam f r a c t i o n a t i o n i s  o f f of d i s s o l v e d m a t e r i a l from a s o l u t i o n v i a  Table 2 Schematic  C l a s s i f i c a t i o n o f t h e A d s o r p t i v e Bubble S e p a r a t i o n  Techniques  A d s o r p t i v e b u b b l e s e p a r a t i o n methods  Foam S e p a r a t i on  Non-foaming a d s o r p t i v e bubble s e p a r a t i o n  Bubble f r a c t i o n a t i on  Solvent sublation  Foam fractionation (froth) Flotation  1 Ore  Macro-  Mi c r o -  Prec pi t a t e f lotati<  1 Ion  Molecular  Adsorbing  tn  16  adsorption  at  flotation  the  (26),  frothing  is  the  surfaces.  removal  of  Froth  f l o t a t i o n ,  particulate  flotation  flotation,  (26)  is  in  the  turn,  h a s many  separation  of  minerals.  the  separation  of  macroscopic  particles.  (27)  is  the  separation  of  microscopic  particles,  colloids  or  separation  microorganisms of  colloids  Molecular  flotation  molecules  by  product.  Adsorbing  foaming  through  removed  is  to  one  be  S t i l l ,  (under  the  with  Lemlich  separation  termed  of  which  colloid  flotation  is  colloidal  especially  gives  the  the  colloid  surface  collector  on  Microf1otation  flotation).  inactive an  insoluble  separation  particles  of  which  a  are  flotation.  another  removed  be  Macroflota-  conditions,  a  adsorption by  certain  may s o m e t i m e s  Theoretically from  by  subdivisions.  is  then  simply  material  tion  solute  or  (foaming). Froth  Ore  bubble  in  is  that  ion  and p r e c i p i t a t e  with  precipitated  (22)  defines  the  latter  before  three  flotation  process  the addition  types  of  the of  differ component collector.  precipitate  flotation: a)  P r e c i p i t a t e f l o t a t i o n of the f i r s t kind i n v o l v e s the f l o t a t i o n o f precipitated p a r t i c l e s by a s u r f a c e - a c t i v e species; the latter i s not a c h e m i c a l constituent o f t h e p r e c i p i t a t e s u b s t a n c e and o c c u r s o n l y on t h e s u r f a c e o f t h e p a r t i c l e s .  b)  P r e c i p i t a t e f l o t a t i o n of the second kind u s e s no s u r f a c t a n t t o f l o a t t h e p a r t i c l e s b u t two h y d r o p h i l i c ions p r e c i p i t a t e to form a s o l i d w i t h hydrophobic surface.  17  c)  P r e c i p i t a t e f l o t a t i o n o f the t h i r d t y p e is a form o f ion f l o t a t i o n , in w h i c h i o n s a r e . p r e c i p i t a t e d by s u r f a c t a n t s , and the . r e s u l t i n g p a r t i c l e s are f l o a t e d .  According tation  requires  collector,  precipitate  which  of  the collector.  to  gas flow  rate  In  rate;  and to i o n i c  total  removal.  relatively  the  tion,  between  the reader  of  Aqueous A  molecules solutions, anomalies solutions.  any two o f  these  distinctive  i s their  on each  known  in the physical  processes  and  hand  i s  concen-  Micelle  Since  i s  very  in the  defini-  treatise  specific  of  method.  Concentration  Surfactants of  surface  to form,  as m i e e l l e s ,  takes  active  ions  in the interior  and e l e c t r i c a l  formation  but notthe  strength.  to the excellent  feature  tendency  aggregates  Micelle  of  ionic  collector  the rate  i s an o v e r l a p  and C r i t i c a l  Solutions  both  sensitive  to  and c o l l e c t o r  of  there  removal;  of  that  i s very  on t h e o t h e r  independent  details  Formation  rate  f l o -  systems  100 times  removed  affects  flotation  i s referred  (22) f o r more  Micelle  which  t h e time  of  t h e amount  to gas flow  and completely  a n d most  in  strength  i s  i n some  ion flotation the rate  determines  insensitive  Lemlich  1.4  affects  Precipitate  difference  subtle  addition,  ion  concentrations  i s effective  ion concentration  which  which  (28), while  or greater  flotation  the colligend  concentration  and Johnson  stoichiometric  in  tration  t o Rubin  place  with  of  their  resultant  properties above  and  a  of  their  certain  18  temperature  [Krafft  point)  M i c e l l e Concentration). in and  s u c h a way t h a t  The a g g r e g a t e s a r r a n g e the hydrocarbon chains  d i r e c t e d away f r o m  ends a r e i n c o n t a c t  and a c e r t a i n c o n c e n t r a t i o n  themselves  are close  t h e w a t e r , and t h e c h a r g e d  with  the water  ( 2 3 ) . This  the m o l e c u l e forming  part  structure  i n t h e a m p h i p a t h i c monomer  i t s surface  capability  active properties  as w e l l .  Therefore,  t o monomers, t h e m i c e l l e s w h i c h are  not s u r f a c e The  increase  point  i n the surfactant  A b o v e t h e Krafft  saturation concentration Critical Micelle  point  form  reached a t a c e r t a i n  the  constituent  monomers  tion-dissociation that micelles centrations  only  agent e x i s t s ( 3 2 ) . At t h i s stays  almost constant  involves  become d e t e c t a b l e  point  and i s  (33,34,35,36,37). accuracy  the formation  equilibrium.  as t h e t o t a l  of the s u r f a c t a n t  the m i c e l l e i s the  Concentration  to emphasize t h a t  by a s u d d e n  ( 3 1 ) . For that reason  In t h e i n t e r e s t s o f s t r i c t important  contrast  have a h y d r o p h i l i c e x t e r i o r ,  solubility,  t h e m i c e l l e and n o t t h e s o l i d  called  on  but i t s m i c e l l e  (20) i s c h a r a c t e r i z e d  thermodynamically preferred  the  The p r e s e n c e  active (29).  Krafft  negligible.  gives  confers  i n striking  t e m p e r a t u r e , below which t h e s o l u b i l i t y is  together  hydrophilic  t h e m i c e l l e s a t h e r m o d y n a m i c a l l y more s t a b l e s t a t e . of a hydrophobic  [Critical  of  (38) i t i s micelles  a r a p i d , dynamic, Experimentally  from  associa-  i t i s found  over a narrow range o f con-  concentration  of s o l u t e  i s increased.  19  As s u c h , the c o n c e n t r a t i o n dependence of the degree of m i c e l l i z a t i o n changes g r a d u a l l y . transition  is  A truly  abrupt, discontinuous  excluded ( 3 2 , 3 9 , 4 0 ) .  Besides  there  is  not a  unique number of monomers which can form a m i c e l l e but a range with r e l a t i v e l y (41).  This i s  micellar  wide l i m i t s .  in agreement with the f a c t  size varies  temperature,  Hence m i c e l l e s  c o n c e n t r a t i o n of s u r f a c t a n t ,  length and s t r u c t u r e .  that the  It  nature of c o u n t e r i o n ,  follows  appear, each with a s l i g h t l y  different  Because  the C r i t i c a l  Micelle  but many kinds  i o n i c dependence and  at which m i c e l l e s  depends on the s e n s i t i v i t y  probe used.  chain  that in the C r i t i c a l  charges or even none at a l l  The c o n c e n t r a t i o n detectable  average  c o n c e n t r a t i o n of  C o n c e n t r a t i o n region not one kind of m i c e l l e ,  different  polydisperse  c o n t i n u o u s l y with c o n d i t i o n s such as  c o u n t e r i o n s or other a d d i t i v e s ,  most l i k e l y  are  of the  Micelle  (35).  become  first  experimental  Concentration  not a s h a r p l y d e f i n e d p o i n t above which some p r o p e r t i e s qualitatively  different  of a s o l u t i o n in t h i s manner.  There i s ,  of c o n c e n t r a t i o n s Operationally,  from those below i t ,  all  is are  properties  region are expected, to vary, in. a continuous  nevertheless,  a relatively  narrow  region  in which those changes are most marked.  the C r i t i c a l  Micelle  C o n c e n t r a t i o n , is  obtained by p l o t t i n g some s o l u t i o n property a g a i n s t c o n c e n t r a t i o n and taking i t from monomeric behavior  to be the f i r s t  (37).  evident  usually  surfactant deviation  20  Well  above t h e C r i t i c a l  aqueous m e d i a , t h e r e  occur extensive  m i c e l l e s , which a r e o f t e n if  difficult  the m i c e l l e s are i o n i c .  many p h y s i c a l  Micelle Concentration,  properties  particularly solutions,  take place  at the C r i t i c a l  where m i c e l l e s f i r s t f o r m .  "the second C r i t i c a l  phenomena i s n o t w e l l  to unravel,  of s o l u t i o n s e x h i b i t breaks or kinks  t i o n s where such b r e a k s o r k i n k s as  i n t e r a c t i o n s between  In such c o n c e n t r a t e d  somewhat s i m i l a r t o t h e ones t h a t M i c e l l e Concentration  in  The  concentra-  happen a r e f r e q u e n t l y  described  M i c e l l e Concentration"  understood  changes i n i n t e r - m i e e l 1ar  but i t c l e a r l y  i n t e r a c t i o n s as a l s o  (42,43).  This  involves monomer-micelle  interactions. The with the  information  those f a c t s that w i l l  i n general,  surfactants  has been e x c l u s i v e l y c o n c e r n e d  be p r o v e n  r e s u l t s o f t h e p r e s e n t work.  micelles, on  preceding  important  i n discussing  For a complete d i s c u s s i o n o f  a n y one o f a number o f e x c e l l e n t  or surface  activity  could  texts  be c o n s u l t e d ( 3 5 ,  36,37,44,45).  1 .5  A Word o f C a u t i o n Flotation  Concerning  t h e D e s i g n and A n a l y s i s o f  Experiments (46)  A properly designed experimental investigation of t h e e f f e c t s o f c h a n g e s in f l o t a t i o n v a r i a b l e s w i l l p r o v i d e f o r measurement of t h e e f f e c t s of i n t e r a c t i o n s among t h e variables. Y e t many f l o t a t i o n e x p e r i m e n t e r s  21  a r e v i c t i m s o f e r r o n e o u s i d e a s as t o how experimentation should proceed. They a t t a c k i n v e s t i g a t i o n of s e v e r a l p r o c e s s v a r i a b l e s by h o l d i n g a l l c o n s t a n t e x c e p t o n e , v a r y i n g i t o v e r a range u n t i l an a p p a r e n t l y optimum l e v e l f o r b e s t r e s u l t s is o b t a i n e d . They t h e n h o l d t h i s variable c o n s t a n t a t i t s optimum l e v e l , v a r y i n g a s e c o n d v a r i a b l e u n t i l i t s optimum l e v e l is found. H o l d i n g t h e f i r s t two c o n s t a n t a t t h e i r s u p p o s e d o p t i m u m s , t h e y p r o c e e d in s i m i l a r f a s h i o n f o r the t h i r d v a r i a b l e . F i n a l l y , t h e y end up w i t h what t h e y c o n s i d e r t o be an optimum c o m b i n a t i o n o f l e v e l s o f the v a r i a b l e s . I m p l i c i t in such a p r o c e d u r e i s t h e a s s u m p t i o n t h a t t h e e f f e c t s o f each v a r i a b l e are independent of the l e v e l s of a l l o t h e r s ; t h e r e a r e no i n t e r a c t i o n s . In f l o t a t i o n t h i s i s s e l d o m t h e c a s e , nor i s t h e c o m b i n a t i o n so a r r i v e d a t n e c e s s a r i l y t h e op t i mum. No one has any r e a l u n d e r s t a n d i n g o f any f l o t a t i o n o p e r a t i o n u n l e s s he u n d e r s t a n d s t h e n a t u r e of t h e s i g n i f i c a n t i n t e r a c t i o n s among the important process v a r i a b l e s . Such u n d e r s t a n d i n g can s e l d o m be deduced from t h e o r e t i c a l k n o w l e d g e , a n d , in f a c t , most a p p a r e n t d i s c r e p a n c i e s between e x p e c t e d b e h a v i o u r based on t h e o r y and a c t u a l b e h a v i o u r o f f l o t a t i o n s y s t e m s are p r o b a b l y s i m p l y m a n i f e s t a t i o n s of such interactions. O n l y by i n c l u d i n g s t u d i e s of t h e e f f e c t s o f s e v e r a l v a r i a b l e s in t h e same g r o u p o f e x p e r i m e n t s can s u c h i n t e r a c t i o n s be p r o p e r l y d e l i n e a t e d , and t h i s i s b u t one more r e a s o n f o r p r o c e e d i n g by g r o u p s o f t e s t s in any e x p e r i m e n t a l p r o g r a m .  Chapter  2  OBJECTIVES OF THIS WORK  The the  color  defined color  efficiency  fraction  i n terms  from  of the f l o t a t i o n kraft mill  process i n  effluent  o f the percentage of c o l o r  technique i s applied  to t h i s  removing  is generally removed.  purpose.  A standard  In h i s t h e s i s  H e r s c h m i 11 e r ( 4 ) i n t r o d u c e d t h e c o n c e p t o f f l o a t a b l e under c e r t a i n to  determine  ments i t was expressing  assumptions them  and  suggested  (see Appendix  found  C).  the f l o t a t i o n  techniques are a f f e c t e d  this  essay.  The  by t h e r e q u i r e d  results  of  both  stage  be p r o v e n  was  t o d e v e l o p a method o f e x p r e s s i n g t h e p r o c e s s  result.  The  amount o f f l o a t a b l e  feasible  (see Appendix  determined with a completely  C).  Through t h i s ,  i t was  to express the response o f the p r o c e s s i n t h r e e  c o m p l e m e n t a r y ways: solids  s o l i d s was  a) % s u r f a c t a n t  floated/surfactant  floated,  f l o a t e d , c) % s o l i d s  22  and  later in  i n mind  approach  reason, the f i r s t  accurate in  filtration  i t will  experi-  objective  different  For t h a t  technique  After preliminary  efficiency.  can even be h i g h l y m i s l e a d i n g , as  solids  an a n a l y t i c a l  t h a t n e i t h e r p r o c e d u r e was  work  b) r a t i o floated.  of  23  Once t h e p r i m a r y to  difficulty  l a y out the experimental  1.  Studies  The m a i n o b j e c t i v e  objectives  on the of these  b e h a v i o r o f an a q u e o u s  m i l l waste  Studies  water.  each o f t h e r e s p o n s e s  was  studied  a general  surfactant: dosages  f l o t a t i o n process  investigated  f a c t o r s o r t h e optimum  established of  2.1  regression  and a p p l i e d  the experiments  Batch  model  surfactant.  to i n v e s t i g a t e the  applied  e f f e c t s o f pH and s u r f a c t a n t was  possible  follows:  experiments  any s i g n i f i c a n t i n t e r a c t i o n among them. results,  i t was  of the pure  s o l u t i o n of the  on the  The  as  solved,  floatability  i ) a t d i f f e r e n t pHs i i ) at d i f f e r e n t surfactant  2.  was  i n order  to  d o s a g e on  to d i s c l o s e  D e p e n d i n g on t h e  f o r the e f f e c t s of the  set of conditions  to a continuous  process.  was  t o be  The  outline  was:  Experiments i) ii)  iii)  kraft  i n t e r r e l a t i o n between % s u r f a c t a n t f l o a t e d , pH and amount o f s u r f a c t a n t a d d e d , i n t e r r e l a t i o n between r a t i o o f s o l i d s f l o a t e d / s u r f a c t a n t f l o a t e d , pH and amount of s u r f a c t a n t added, i n t e r r e l a t i o n between % s o l i d s f l o a t e d , pH and amount o f s u r f a c t a n t a d d e d .  24  2.2  Continuous  Experiments  S i n c e most p r e v i o u s work had been done on a b a t c h b a s i s , a n d s i n c e t h e p r o c e s s , i f i t w e r e e v e r t o be u s e d i n d u s t r i a l l y , would.have t o operate using on  thebest c o n d i t i o n s observed  a continuous  3.  operation  Studies  and  elapsed  was  kept o f the observed  solids  time  on  of  the  kraft  in  the  of  waste  effluent  pH  adjustment  A careful  water.  changes i n c o l o r  t o the o r i g i n a l  the  record  v a l u e s and t o t a l  after  sample.  i t s pH a d j u s t The r e l a t i v e  was a l s o  noticed but i n a rather  behavior  of  manner.  4. waste  influence  mill  filterabi 1 i t y o f the e f f l u e n t qualitative  i n b a t c h r u n s , w e r e done  basis.  content o f the ageing  ment, i n c o m p a r i s o n  continuously, experiments,  Studies following  acidification;  on  the  sequences:  the  kraft  i ) acidification-a  mill  1kalization-  i i ) alkalization-acidification-alkalization-  a c i d i f i c a t i o n.  /  Chapter  3  EXPERIMENTAL  3.1  Batch Studies 3.1.1  Design of Experiments As m e n t i o n e d ,  experiments were:  t h e main o b j e c t i v e s  a) to determine  of the s e t of batch  i f t h e two f a c t o r s ,  pH and  amount o f s u r f a c t a n t a d d e d , had an i n f l u e n c e on t h e r e s p o n s e s ; b) t o d i s c l o s e w h e t h e r t h e r e was a s i g n i f i c a n t between t h e f a c t o r s tions  and i f s o , t o e s t a b l i s h  f o r the process.  For these purposes  e x p e r i m e n t s was d e s i g n e d . replication variables order.  per c e l l ,  {Model  I)  The s e l e c t e d i) ii)  iii)  interaction  t h e optimum a set of 3  The s e t was c h o s e n w i t h  w i t h evenly spaced  and e x e c u t e d  factorial  one  values of the f i x e d  i n a completely  d e s i g n had t h e f o l l o w i n g  randomized  advantages:  Any i n t e r a c t i o n b e t w e e n t h e f a c t o r s was d e t e c t a b l e ; A g e n e r a l r e g r e s s i o n model f o r t h e e f f e c t o f t h e m a i n f a c t o r s on t h e r e s p o n s e c o u l d have been e a s i l y computed i n t h e e v e n t t h a t no i n t e r a c t i o n had been p r e s e n t . Any e f f e c t due t o a g e i n g o f t h e e f f l u e n t w i t h i n one s e t o f  25  2  condi-  26  e x p e r i m e n t s o r any v a r i a t i o n i n t h e q u a l i t y of t h e e f f l u e n t f r o m s e t t o s e t w o u l d have been c o u n t e r a c t e d by t h e r a n d o m i z a t i o n o f the experimental o r d e r . To  collect  the r e q u i r e d data f o r the e i g h t e e n  ments i t was  necessary  experiments,  grouped  The  t h i s work.  and at  through  Laboratory a pressure  the working gas  batch  s e t s ; see A p p e n d i x  are summarized i n T a b l e  2 shows a s c h e m a t i c a i r was  of the apparatus  passed  r e g u l a t o r and  adjusted with a rotameter.  All  o f 27  experi-  D. 3.  Apparatus Figure  cell  a total  i n three d i f f e r e n t  eighteen s e l e c t e d experiments  3.1.2  in  to c a r r y out  intended  p r e s s u r e o f 10  The  to the  flotation  i t s f l o w was  rotameter  was  p s i g w i t h a bubble  f l o w s a r e r e p o r t e d i n ml/sec a t 10  psig  used  measured calibrated  meter.  and  room  temperature. The glass cell  bottle was  flotation from  a b o u t 16  volume o f 2.5  glass pore  sparger s i z e was  cms  c o n s i s t e d of a l a r g e  t h e b o t t o m had  i n diameter  pyrex  been r e m o v e d .  a t the  l i t e r s , w i t h room f o r a two  centimeter froth The  which  cell  t o p and and  The  held a  one-half  bed.  diffuser  c o n s i s t e d o f a 5.4  (Corning Glass Works). o f 4-5.5  microns.  The  The  cm  diameter  fritted  nominal-maximum  d i f f u s e r was  positioned  Table 3 Experimental  Results  Days A f t e r S a m p i i ng  from %  the Factorial  Surfactant Floated  Experiments  Solids Floated Surfactant Floated  % Solids Floated  ppm o f S u r f a c t a n t Added  Set  3.6  100  2  5  90.38  1 .67  20.49  3.6  1 00  3  7  90.0  1 .47  24.26  3.6  1 50  2  4.  87.33  1 .34  20.80  3.6  1 50  3  3  80.33  0.875  21 .65  3.6  200  2  12  81 .25  0.97  20.08  3.6  200  2  19  81 .  0.802  19.11  4.6  100  2  17  30.0  0.80  3.41  4.6  100  3  5  17.0  1 .24  4.0  4.6  1 50  2  7  67.66  1 .36  1 5.66  4.6  1 50  2  13  70.66  1 .25  17.25  4.6  200.  2  16  75.0  0.94  18.23  4.6  200  3  6  51 .0  0.64  13.23  5.6  100  1  14  24.5  0.53  1 .78  5.6  100  2  8  27.0  0.185  0.581  5.6  1 50  2  6  24.66  0.16  0.71  5.6  1 50  3  1  6.66  .53  5.6  200  3  2  25.0  1 .78  17.52  5.6  200  3  20  32.0  0.88  11 .27  PH  •  0.819  28  f i g u r e 2.  SCHEMATIC DIAGRAM OF THE APPARATUS U S E D IN T H E B A T C H EXPERIMENTS  Stirrer  Speed  pH Meter scum  Controller  FLOTATION CELL Diffuser  Y Rubber  Bung  Lab. Air  Valve X Pressure Regulator  Rotameter Manometer Valve  Gauge  29  11.5  cms f r o m  which  also  the top of the vessel  sealed  the bottom  removed m a n u a l l y w i t h A digital The  color test  by means o f a r u b b e r  of the c e l l .  a small  pH m e t e r  The f r o t h  bung,  was  scoop. was u s e d f o r m e a s u r i n g  t h e pH.  r e a d i n g s w e r e t a k e n i n a U n i c a m SP.800B s c a n n i n g  s p e c t r o p h o t o m e t e r and t h e s u r f a c t a n t c o n c e n t r a t i o n s  were  determined c o l o r i m e t r i c a l l y  using  Spectronic  20.  stirring  Provisions  available  forinitial  a Bausch  of the surfactant  i n t h e form o f a l a b s t i r r e r w i t h  3.1.3  waste  Crown Z e l l e r b a c h  w a t e r s used were d i f f e r e n t  (ElkFalls  Division) effluent.  was s h i p p e d f r o m t h e m i l l i n f i v e - g a l l o n  frozen.  some was s t o r e d  samples The  containers;  from waste  upon  a t a t e m p e r a t u r e o f 4°C and t h e r e s t  have a marked  i n f l u e n c e on t h e e x p e r i m e n t a l  results,  i t was n e c e s s a r y t o keep a c a r e f u l  sample's  history.  dissolving  The c o l l e c t o r  a weighed  quantity  bromide  (obtained  content  (0.10%) methanol.  the s t i r r e r  runs.  control.  As t h e t i m e and t e m p e r a t u r e o f s t o r a g e o f t h e w a s t e  water could  and  speed  were  Materials The  arrival  and Lomb  from  solution  record  of the  was p r e p a r e d by  of didodecyldimethylammoniurn  Eastman K o d a k ) i n 10 ml o f l o w w a t e r The r e q u i r e d  speed were d e t e r m i n e d  amount o f m e t h a n o l  i n e a r l i e r experimental  30  3.1 .4  Procedure One and a h a l f  were p o u r e d equal  into  effluent  of the solution  Dilute  sodium  f o r the p a r t i c u l a r was r e c o r d e d , t h e n  solids  cell  hydroxide,  analysis.  solution  test. two  In the t h i r d performed  taken p r e v i o u s l y  t o i t s pH  s t i r r e r was p l a c e d i n t h e e f f l u e n t and s t a r t e d  RPM.  At t h i s  point the c o l l e c t o r  of a hypodermic stirring  tation  cell  cc/sec. regarding  solution  s y r i n g e a t an a p p r o x i m a t e  was c o n t i n u e d f o r f i v e  t h e same s p e e d .  Next  the s t i r r e r  liters saved set of on  adjustment. a t 950  minutes a t  was removed f r o m  the f l o -  and a d j u s t e d t o 1.66  z e r o t i m e as t h e moment when t h e b u b b l e s  minutes, first  Once t h e s e t t i m e had e l a p s e d  t h e a i r f l o w was s t o p p e d and s a m p l e o f t h e r e m a i n i n g t i o n were t a k e n t o a n a l y s e f o r c o l o r , residual  samples  r a t e o f 0.2 c c / s e c .  The a i r was a l l o w e d t o b u b b l e f o r f i f t e e n  the d i f f u s e r .  The  was added by means  additional  and t h e a i r f l o w s t a r t e d  emerged t h r o u g h  w i t h an  and t h e r e s t  t h e same a n a l y s e s w e r e a l s o  of the d i l u t e d  The  b a t t e r y j a r and m i x e d  to the f l o t a t i o n  and t o t a l  experiments  water  a c i d was added t o a d j u s t t h e pH o f t h e  were t r a n s f e r r e d color  o f t h e s t o r e d waste  water.  to a value required  temperature  The  a one g a l l o n  volume o f d i s t i l l e d  or h y d r o c h l o r i c  for  liters  total  solu-  s o l i d s and  surfactant. The  experiments  study the s u r f a c t a n t  performed  with  distilled  b e h a v i o r were c a r r i e d  water to  out with the  31  same g e n e r a l p r o c e d u r e . H e r s c h m i 1 1 e r s m o d i f i e d c o l o r 1  was used The  unaltered  to determine  the c o l o r  of the  tration  of r e s i d u a l  surfactant  determination of f l o a t a b l e suggestion for  samples.  but l a t e r  f o r determining the (see Appendix  solids  on t h i s  was  was  C).  done a f t e r  found  3.2  was d e v e l o p e d  (see Appendix  concen-  At f i r s t  the  Herschmi11er' s  t o be n o t s a t i s f a c t o r y  t h e e x p e r i m e n t a l work i n t e n d e d and t h e r e a f t e r  approach  a  different  C).  Continuous Studies 3.2.1  Apparatus The c o n t i n u o u s a p p a r a t u s a s s e m b l e d  matically  i n F i g u r e 3.  component g r o u p s : the  I t c a n be d i v i d e d  the e f f l u e n t  with  system  an i n l e t bottom  A cartridge  consisted  connected filter  p r e v e n t i t from  was u n d e r t a k e n manufacturers  into  column.  o f a 13 g a l l o n ,  f o r regulated  i s shown  and s u r f a c t a n t  p r e m i x i n g t a n k and t h e f l o t a t i o n  feeding  to  (4)  method o f van S t e v e n i n c k and Maas f o r q u a t e r n a r y  ammonium d e t e r g e n t s was a d a p t e d  its  test  laboratory  three functional feeding The  placed i n - l i n e  p o l y e t h y l e n e tank  a i r on t o p and  tank.  of the rotameter  b u t no s e n s i b l e d e p a r t u r e was curve.  with  before the rotameter  clogging. C a l i b r a t i o n  calibration  system,  effluent  v i a a rotameter to the mixing  was  sche-  found  The s u r f a c t a n t  from t h e  solution  32  figure  3.  S C H E M A T I C D I A G R A M OF T H E FLOTATION A P P A R A T U S U S E D IN T H E C O N T I N U O U S EXPERIMENTS Syringe Pump with Surfactant ibber Bung S C U ,  UUB^  FLOTATION COLUMN Open •Channel  Manometer  33  was  prepared  i n a separate  s y r i n g e pump. premixing  Both  c o n t a i n e r and t h e n  streams d i s c h a r g e d  the premixing  required  tank.  I t was c o n v e n i e n t l y s i z e d  r e t e n t i o n time.  used i n t h e b a t c h  A rubber  experiments  A peristaltic  pump c o u p l e d  the m i x t u r e  to the f l o t a t i o n  placed  provided  to a v a r i a b l e column.  had  t o be p r e v i o u s l y d e t e r m i n e d  i n s i d e diameter removal  liquid  feed  fitted  r a t e s used  inches i n  Three one-inch  column.  Two l i q u i d  diameter from  feed p o s i t i o n s  two p o r t s and one was  from t h e column bottom.  a l l o w i n g a wide v a r i a t i o n  position  s p e e d pump.  delivery  1 5 , 27 and 39 i n c h e s  were l o c a t e d o p p o s i t e t o t h e f i r s t  quite versatile  O.D.  carrying conduits.  c o l u m n was t h r e e  p o r t s were p r o v i d e d  placed four inches  mixing.  f o r b o t h pumps.  and f o u r f e e t h i g h .  the bottom f l a n g e o f t h e  The s t i r r e r  T y g o n t u b i n g 1/4  required s e t t i n g s f o r the d i f f e r e n t  flotation  in it.  speed d r i v e t r a n s f e r r e d  The  plastic  to give the  the necessary  employed f o r a l l t h e d i f f e r e n t  The  served  bung was u s e d t o s e a l  was  and  the top of the  i t s bottom removed,  t h e c o n t a i n e r and a s h o r t o u t l e t  froth  a  tank. A glass b o t t l e , with  as  into  added t h r o u g h  The s y s t e m was in liquid  height  i n t h e c o l u m n , e n h a n c e d by t h e v a r i a b l e  The d i f f u s e r  from t h e batch  t o t h e bottom o f t h e column.  experiments  The same  was  instruments  p r e v i o u s l y d e s c r i b e d w e r e u s e d f o r a n a l y s i s and pH  adjustment.  34  3.2.2  Materials These were the  same as  those  used  i n the  diluted  with  an  batch  studies.  3.2.3  Procedure The  of d i s t i l l e d steps  raw  e f f l u e n t was  w a t e r and  took p l a c e  i n an  both o p e r a t i o n s . t a n k and  The  adjusted  total  dissolved  i n methanol  s o l u t i o n was  solids  transferred  to the  was  into  allowed  delivered  analysis. up  A f t e r two  RPM.  100  mg  in  the  The  s u r f a c t a n t was  the  adjusted  as  s p e e d was  set  t o keep t h e  During  Next, the  a e r a t i o n of the  r a t e was  adjusted  surfactant-waste of  e f f l u e n t from  the  column.  The  t a n k was  c o l u m n was  t o 1.66  mixture  the  was  at  ratio  r e t e n t i o n time the  first  discarded.  commenced; t h e a i r  cc/sec connected  liquid  the  and  premixing  f i v e minutes.  to  stirrer  The  t a n k was  and  pressurized effluent  stirrer  added so  was  laboratory a i r  f l o w was  The  for  10 mg/cc  of s u r f a c t a n t / 1 i t e r of e f f l u e n t .  e i g h t minutes the  inlet  the e f f l u e n t  of  or t h r e e minutes the  950  facilitated  weighed s u r f a c t a n t  Regulated  The  s y r i n g e pump were s t a r t e d .  two  Samples were saved  t h e w a s t e t a n k and tank.  amount  These  into  to a c o n c e n t r a t i o n  the  flow  poured  The  s y r i n g e pump.  to the m i x i n g  rate.  t o 3.6.  open g l a s s c o n t a i n e r w h i c h  i t s temperature recorded.  c o l o r and  desired  i t s pH  equal  level  ( a t 10 to the was  p s i g ) and lowest  the liquid  allowed t o r i s e  to  35  t h e r e q u i r e d h e i g h t , and p r o c e s s was times The  and  running  fifteen  second  total  extra minutes,  the f i r s t  taken f i f t e e n  were a n a l y s e d  later.  for residual  the  hold-up  s a m p l e was  minutes  drawn.  A l l the  s u r f a c t a n t and  solids. I t must be e m p h a s i z e d , t h a t any  the process premixing On  Once  u n d e r t h e s e c o n d i t i o n s f o r two  s a m p l e was  samples withdrawn  kept c o n s t a n t t h e r e a f t e r .  attempt  c o n t i n u o u s l y o m i t t i n g the s t i r r i n g  stage or the e n t i r e  t h e o t h e r h a n d , one  qualitative  highly  during  continuous  run i n  s t a g e was  satisfactory.  the  run  the  s t a g e c o m p l e t e l y d i d not  the a i r e n t r a i n e d d u r i n g the s t i r r i n g s o u r c e o f a e r a t i o n ; was  made t o  succeed.  which only  Chapter  4  RESULTS AND DISCUSSION  4.1  S t u d i e s on t h e F l o a t a b i l i t y Two  establish  series  the e f f e c t s  of Pure  Surfactant  o f b a t c h e x p e r i m e n t s were c a r r i e d of hydrogen-ion  c o n c e n t r a t i o n and o f  s u r f a c t a n t d o s a g e on t h e amount o f s u r f a c t a n t flotation.  As m e n t i o n e d  p r o c e d u r e was a p p l i e d  out to  r e c o v e r e d by  b e f o r e , t h e same g e n e r a l e x p e r i m e n t a l  i n a l l runs.  The t e m p e r a t u r e was  kept  c o n s t a n t a t 25°C.  4.1.1  E f f e c t o f pH All  concentration the  150 ppm  involved  with  the k r a f t m i l l  hydrogen-ion 2.6, 3.6, 4.6 It surfactant  initial  in surfactant.  midpoint of the exploratory  later,  of  experiments  range  effluent.  The c h o s e n amount i n t e n d e d t o be The e f f e c t s  c o n c e n t r a t i o n were d e t e r m i n e d and 5.6 as i n d i c a t e d i s e v i d e n t from  s o l u t i o n s of was  used  of the  a t pH v a l u e s o f  i n F i g u r e 4„  F i g u r e 4 t h a t t h e maximum r e c o v e r y  i s c o n s t a n t over the range  36  pH 3.6-4.6.  At lower  f i g u r e 4.  FLOTATION WATER  O F S U R F A C T A N T IN  surfactant 150ppm  concentration  j  2.6  3.6  PH  4.6  5.6  38  or  higher  drops are  pH v a l u e s  to almost  generally  solution  associated Moreover  floated  even  f o r higher  of  on s i n g l e  their ions  plausible  could  associated  have  For that  species  i n  the data  1 5 0 ppm  established  that  among  them)  of  foaming  aggregates,  the overall  electrostatic  i s  greatly  the percentage  the relative  presence  ammonium  on i o n i c  aggregates  that  the  the property  than  strong  of  amount  surfactant of un-  solution. obtained  c a n be i n f e r r e d At  Since  in  solutions.  dialkylquaternary  reason, of  dilute  chloride  salts  ionized  (49) has held  i n very  and i o n i c  be i n d i c a t i v e  From conclusion  ions  ammonium  as o r d i n a r y  McBain  (23) rather  to conclude  between  by p H .  CMC.  floated  completely  to function  (50,51)  al.  Quaternary  (didodecyldimethylammoniurn  equilibrium affected  et  surfactant  be a l m o s t  Nevertheless  aggregates  the v i c i n i t y  seems  to  are present  Ralston  ionic  depends it  (48).  of  i t s maximum.  considered  ions  chlorides in  half  (47) and t h e r e f o r e  electrolytes  of  the percentage  of  in  Figure  4,  f o r t h e pH v a l u e s  surfactant  25°C,  and  the  following  studied: the  range of pH 3 . 6 - 4 . 6 forms a p l a t e a u o u t s i d e o f which the c o n c e n t r a t i o n of ions in s o l u t i o n i s g r e a t l y d i m i n i s h e d .  4.1.2  Effect The  with  of  second  t h e pH a d j u s t e d  Surfactant series  of  Dosage  experiments  t o 4 . 6 , i t s most  was  promising  performed value  f o r an  39  ion  flotation  t i o n was  process.  determined  ( 2 5 - 2 0 0 ppm)  as  Very w i t h the  The  over  e f f e c t of the  t h e r a n g e 5.41  indicated  in Figure  Krafft  ammonium compounds.  to e s t a b l i s h i n g  of a c e r t a i n  s u r f a c t a n t at a c e r t a i n  main reason fact  the C r i t i c a l  particular  field  Micelle  1  temperature  attitude  has  Concentration  temperature,  Krafft p o i n t the  for this  x IO"* *  higher d i a l kylquaternary  A l l t h e work done i n t h i s  f a r above the  t o 4.2  5  been p u b l i s h e d d e a l i n g  p o i n t f o r the  been l i m i t e d  o f how  x 10~ ,  5.  s c a r c e i n f o r m a t i o n has  expected  surfactant concentra-  regardless is.  The  seems t o l i e i n t h e  that .  .  .  although  the  s o l u b i l i t y  of  amphipathic  e l e c t r o l y t e s changes very rapidly in a small temperature interval when t h e C r i t i c a l Micelle Concentration has been r e a c h e d , the Critical Micelle Concentration is not i t s e l f markedly i n f l u e n c e d by t e m p e r a t u r e . (35)  Ralston  et  al.  (50,51) p o i n t e d out  Micelle Concentration it  can  be  s e e n t h a t as  slope of the critical for  on  temperature.  the  precritical  temperature  ranging  Winston  (33)  found  no  Micelle  Concentration  From t h e i r  from  at almost 20°  significant  Critical  experiments  i s i n c r e a s e d , the  r a n g e becomes s t e e p e r  point i t s e l f occurs  temperatures  the dependence of  the  t o 60°C.  but  the  same c o n c e n t r a t i o n Hutchinson  d i f f e r e n c e i n the  and  Critical  o f dodecylammoniurn c h l o r i d e i n a  temperature  i n c r e a s e o f 10°C.  established  20°C as  t h e Krafft  Adam and  Pankhurst  point f o r hexadecyl  (52) (cetyl)  40  figure 5,  F L O T A T I O N OF S U R F A C T A N T WATER 100 90 80  m  o  o  "•  °  \  70 60  Z  1 #  IN  \  .  50  o  30 20 10 0  o e x p e r i m e n t a l value — t h e o r e t i c a l value . pH 4.6  i  50  i  100  i  15©  ppm ©f s u r f a c t a n t added  i  200  41  trimethylammonium for 10  bromide.  The C r i t i c a l  didodecy1dimethylammonium  _lf  c h l o r i d e i s given  m o l e s / l i t e r ( 7 5 ppm) by S h i n o d a  (34) m e n t i o n e d  out,  b u t no r e f e r e n c e  as 1 .8 x  The o r i g i n a l  paper  i s made c o n c e r n i n g t h e  Krafft point. Another important  Critical  Micelle  is  or s l i g h t l y  equal  (36).  (36).  Concentration  30°C as t h e t e m p e r a t u r e a t w h i c h t h e e x p e r i -  ment was c a r r i e d expected  Micelle  piece of information i s that the  Concentration  Thus, bearing  less  than  f o r an a l k y l q u a t e r n a r y b r o m i d e i t s corresponding  i n mind a l l t h e s e  facts,  chloride  i t will  be  assumed:  A quick  a)  The C r i t i c a l M i c e l l e C o n c e n t r a t i o n didodecy1dimethy1ammoniurn bromide i n t h e v i c i n i t y o f 75 p p m . (36)  b)  The t e m p e r a t u r e m e n t a l w o r k was t h e Krafft point surfactant.  of is  at which the e x p e r i done (25°C) is above o f the referred  i n s p e c t i o n of the experimental  results  (Table  4)  indicates  t h a t any i n c r e a s e o f s u r f a c t a n t c o n c e n t r a t i o n  a certain  critical  p o i n t causes a marked d e p r e s s i o n  percentage recovered critical  by f l o t a t i o n .  Additionally,  i nthe  below  c o n c e n t r a t i o n , the percentage of s u r f a c t a n t  levels out at a d e f i n i t e This  critical  constant  above  this  floated  value.  point i s regarded  (32,33,39,53,54,55,56,57,58,59,60) a s ,  by most  authors  Table 4 Experimental  Results  Obtained  Bromide  Concentration  i n ppm  %  Floated ± 3%  f o r Didodecyldimethylammonium  a t pH 4.6 and 25°C  Amount n o t F l o a t e d , i n ppm  Amount in  Floated, ppm  T h e o r e t i c a l Amount t o be f l o a t e d , i n ppm  25  93.12  1 .72  23.28  22.5  50  87.50  6.25  43.75  45.0  100  72.5  27.50  72.5  72.5  150  53.33  70.0  80.0  72.5  200  32.50  135.0  65.0  72.5  43  . . . a saturation point for single surfactant i o n s ; above t h i s concentration m i c e l l e s f o r m , and any s u r f a c t a n t in e x c e s s o f t h i s c o n c e n t r a t i o n w h i c h i s added t o the s o l u t i o n is e n t i r e l y in t h e form o f m i ceI Ies . It  was  already  compounds  associate  aggregates; Critical  facts  followed  Micelle  attributed into  mentioned  that  first,  higher  a t low c o n c e n t r a t i o n s ,  by t h e f o r m a t i o n  Concentration  aggregates  i t i s possible  (34).  Taking i n t o  once  ammonium ionic the  The m i c e l l e s  of undissociated  to conclude from  into  of micelles  i s reached.  to the i n c o r p o r a t i o n  the i o n i c  dialkylqua ternary  are  molecules  account  the obtained  a l l these data:  a)  The C r i t i c a l M i c e l l e Concentration for didodecy1dimethy1ammoniurn b r o m i d e a t pH 4.6 a n d 2 5 ° C is 72.5 ± 3%. Note the c l o s e agreement of this value with the f i g u r e r e p o r t e d by S h i n o d a (36) f o r the chloride.  b)  Below the C r i t i c a l Micelle Conc e n t r a t i o n o n l y 90% o f t h e s u r f a c t a n t was f o u n d t o be i n t h e i o n i c f o r m a n d h e n c e r e c o v e r a b l e by flotation. Presumably, ageing of the s t o r e d s u r f a c t a n t is partially r e s p o n s i b l e f o r such behavior.  c)  Above the C r i t i c a l M i c e l l e Conc e n t r a t i o n o n l y 72.5 ppm o f t h e s u r factant i s r e c o v e r e d by f l o t a t i o n . The r e m a i n i n g amount i s a s s o c i a t e d either in the form of l a r g e ionic aggregates, ionic m i c e l l e s or neutral micelles. In a n y c a s e t h e a s s o c i a t i o n r e n d e r e d t h e c o l l o i d a l p a r t i c u l a t e s unfloatable.  44  5 compares the  Figure  the a c t u a l v a l u e s . cases  w i t h i n the  analytical  The  following  tration  90%  of the  b) Once t h e CMC f a c t a n t are  theoretical  r e g i o n i s passed  i s most p r o b a b l e  will  be  tration at the  from  72.5  4.2  type  be  pH  a shift  ppm  o n l y 72.5  ppm  on  Concen-  flotation, of the  sur-  of i n t e r a c t i o n  i s present,  The  a t a pH  main p r e d i c t a b l e  the  pH  practical  Flotation  Micelle  Concen-  3.6-4.6 t o a much l o w e r Since  not  5  values  value  outside  i n t e r e s t f o r the  work  confirmed.  Process  Applied to K r a f t  Waste Batch The  Experiments  design  of the  set of batch  been d e s c r i b e d .  P r e l i m i n a r y experiments  most i n s t r u c t i v e  results  be  Micelle  i n the C r i t i c a l  a s s u m p t i o n was  S t u d i e s of the 4.2.1  Critical  values.  3.6-4.6 r a n g e l a c k e d any  Mill  the s u r f a c t a n t  flotation.  r a n g e s 2.6-3.6, 4.6-5.6.  intended, this  the  t h a t the tendency d i s p l a y e d i n F i g u r e  f o l l o w e d at other  d i f f e r e n c e would  i n most  to  s u r f a c t a n t i s r e c o v e r a b l e by  r e c o v e r a b l e by  against  p o i n t s were c a l c u l a t e d  a) B e l o w t h e  B e c a u s e no o t h e r it  of e r r o r a t t r i b u t e d  used f o r d e t e r m i n i n g  basis:  behavior  a g r e e m e n t i s q u i t e good and  percentage  techniques  concentration. the  The  theoretical  obtained, at i n i t i a l  experiments indicated  about the f l o t a t i o n  has that  process  surfactant concentrations  alrea the  would  ranging  45  from  100-200 ppm  and  pH v a l u e s v a r y i n g  t e m p e r a t u r e o f t h e e f f l u e n t was 35°C, a l t h o u g h no a t t e m p t was particular  value.  of k r a f t m i l l o f each  from  made t o f i x i t t o a  I t i s important to s t r e s s  effluent  i s not always  p e n d i n g on t h e t y p e o f wood and s e t o f b a t c h e x p e r i m e n t s was  certain  The  certain  amount  limits  process c o n d i t i o n s .  inspecting  7, and  8 show t h e t y p i c a l  the p l o t s .  i n the A n a l y s i s  samples  levels  T h i s was  average of each  c a n be  on  obvious  t h a t t h e t r e n d s i n t h e d a t a s h o u l d be a n a l y z e d the i n f l u e n c e o f each f a c t o r  Any  effort  effects  caused  at fixed  by t h e s t u d i e d  i t is possible  f a c t o r s would  to s e l e c t  pH  3.6  and  quite  levels  t o draw g e n e r a l i n f e r e n c e s on  t a n t as t h e b e s t p a r a m e t e r s studied  i t becomes  the s e t  (Appendix A ) .  Still,  point,  inferred  c o n f i r m e d beyond  of V a r i a n c e performed  At t h i s  befactor.  of data  other.  de-  Each  performed w i t h d i f f e r e n t  In e a c h c a s e , t h e p r e s e n c e o f i n t e r a c t i o n s  observing  and  t h a t the c o m p o s i t i o n  t h e same.  h a v i o r s o f each r e s p o n s e a t t h e chosen  any d o u b t  The  mill.  F i g u r e s 6,  by j u s t  t o 5.6.  k e p t m o s t l y b e t w e e n 25°  component p r e s e n t v a r i e s w i t h i n  f r o m t h e same  3.6  of the  the main  be m e a n i n g l e s s . 100  ppm  of  f o r the p r o c e s s , w i t h i n  surfac-  the  ranges. S i n c e each  process, i . e .  r e s p o n s e has  a d e f i n i t e meaning  i n the  46  i)  % surfactant floated determines the amount o f s u r f a c t a n t consumed d u r i n g the f l o t a t i o n p r o c e s s , irrespective o f w h e t h e r any c o l o r body i s b e i n g a t t a c h e d to it,  ii)  ratio  of  solids  floated/surfactant  f l o a t e d measures of the f l o t a t i o n iii)  it  also  4.2.1.1 It  to discuss  This  has been  repeatedly  is  three tion the  with  The c h a n g e s  as t h e i n i t i a l  pointed  dosage  bubbling  Thereafter  that  t h e removal  by t h e p r o c e s s  the f l o t a t i o n  of surfactant  process  i s increased  A t 100' ppm, a d a r k t h i c k scum the f i r s t  two o r  a i r i s passed through the f l o t a -  neither  scum n o r foam  c l e a r s o l u t i o n remains u n a l t e r e d .  dosage  out that  a t l o w pHs ( 1 0 , 1 1 , 1 2 , 6 1 ) .  on t o p o f t h e s o l u t i o n , d u r i n g  minutes that cell.  discussion.  the behavior displayed  remarkably i n t e r e s t i n g . formed  Figure  w a s t e s by a d d i t i o n o f c a t i o n i c  i s more s u c c e s s f u l  i n g r a p h s 6, 7, 8.  are  tendencies together.  pH 3.6  i s i n agreement  undergoes  their  be h e l p f u l i n t h e f o l l o w i n g  of c o l o r from k r a f t m i l l surfactants  efficiency  % s o l i d s f l o a t e d g i v e s an i d e a o f the p o s s i b l e amount o f f l o a t a b l e solids t h a t c o u l d be r e m o v e d f r o m t h e e f f l u e n t at c e r t a i n f i x e d c o n d i t i o n s ,  i s mandatory  9 will  a s o r t of process,  i s f o r m e d and  I f the surfactant  i s r a i s e d t o 150 and 200 ppm, s t i l l  t h e scum w o u l d be  47  figure  FLOTATION OF S U R F A C T A N T KRAFT MILL EFFLUENT  6.  IN  48  figure  7.  RATIO OF SOLIDS FLOATED T O S U R F A C T A N T F L O A T E D IN K R A F T MILL EFFLUENT 2.0 •o  0  1.8  0  8  1.6  £  1-4  (0  S  1-2  5  1-0  h  .8  -  .6  -  .4  -  (0  T3 0  o  pH  (0  "D •  MM  o 0)  0 A  .2 0  -  •  3.6 4.6 5.6 i_  50 ppm  • _L  100 of surfactant  150 added  200  49  figure  FLOTATION OF SOLIDS F R O M KRAFT MILL EFFLUENT  8.  50  figure  9  FLOTATION OF SOLIDS FROM KRAFT MILL EFFLUENT  51  formed w i t h i n t h e f i r s t increasing ing by  the process  c a n be made b a s e d on t h e b e h a v i o r i n the studied  followed  ranges:  The m a j o r i t y of the n e g a t i v e l y charged colloids present in the e f f l u e n t are chromophores. Most of t h e s e chromophores a r e not a s s o c i a t e d w i t h any o t h e r chemical s p e c i e s in the s o l u t i o n .  2.  An i n s t a n t a n e o u s c o a g u l a t i o n reaction takes p l a c e between the negatively c h a r g e d c h r o m o p h o r e s and the h y d r o p h o b i c c a t i o n of the s u r f a c t a n t . The complex (sublate) i s i n s o l u b l e , h y d r o p h o b i c and easily s e p a r a b l e by f l o t a t i o n .  3.  The f o a m i n g p r o c e s s d e v e l o p e d at higher surfactant c o n c e n t r a t i o n s m u s t be c a u s e d by t h e e x c e s s o f s u r f a c t a n t ions in solution. T h i s c o n c l u s i o n i s b a s e d on the s i m i 1 a r i t y o f the t y p e o f foam f o r m e d w i t h the one p r o d u c e d in a q u e o u s solution of t h e s u r f a c t a n t a t t h e same p H .  k.  T h e r e m i g h t a l s o be o t h e r c h r o m o p h o r i c species present in the s o l u t i o n but, most l i k e l y , in the form o f neutral, i n s o l u b l e , c o l l o i d a l aggregates which t h e r e f o r e would not i n t e r f e r e w i t h the electrostatic p r o c e s s d e s c r i b e d in ( 2 ) . Nevertheless, they are removed from the s o l u t i o n d u r i n g the coagu1 a t i o n - f 1 o t a t i o n p roces s.  to Figure  8 the percentage of s o l i d s  f r o m t h e e f f l u e n t i s t h e same f o r t h e t h r e e  dosages used.  this  The f o l l o w -  1.  According  analysis  by an  amount o f a heavy c o m p a c t , w h i t e f o a m .  conclusions  floated  few m i n u t e s , b u t f o l l o w e d  This  of the data  trend  i s supported  (Appendix B ) .  means t h a t t h e amount o f s o l i d s  by t h e l i n e a r  surfactant regression  In terms o f F i g u r e that could  9  be p o s s i b l y  52  floated  i s constant  and r a n g e s  f o r e , any s u r f a c t a n t used wasted.  130 t o 160 ppm.  i n excess  There-  o f 100 ppm w o u l d be  F i g u r e 7 c o n f i r m s this c o n c l u s i o n s i n c e t h e " e f f i c i e n c y "  of the process 100  from  ppm.  i s highly  These r e s u l t s  At the beginning coagulation  verify  the e a r l i e r  mechanism i s a  w i t h by any o t h e r  i n the s o l u t i o n .  no i n t e r a c t i o n  in  t h e range under s t u d y .  sur-  chemical  Since the reaction i s  i n s t a n t a n e o u s and t h e s u b l a t e i s i m m e d i a t e l y is  floated,  there  with the s u r f a c t a n t i n excess, at l e a s t F i g u r e 6 i m p l i e s t h a t , a t 100 ppm,  90% o f t h e s u r f a c t a n t i s i n i t s i o n i c  form  f r e e to r e a c t w i t h the chromophores.  This value  suggests  that the i o n i c aggregates  so r e a d i l y  i n the  kraft  do n o t f o r m  and t h e r e f o r e  e f f l u e n t a s t h e y do i n a q u e o u s s o l u t i o n s .  because o f the presence waste.  over  c o n c l u s i o n s made.  b e t w e e n c h r o m o p h o r e s and c a t i o n i c  i s not i n t e r f e r e d  species present  a t s u r f a c t a n t dosages  of the process, the primary  reaction  f a c t a n t which  decreased  Most  likely  of other competitive species i n the  A t c o n c e n t r a t i o n s higher than  100 ppm, t h e % o f  surfactant floated  does n o t s t a y c o n s t a n t a t 90%; i n s t e a d i t  begins  in a linear  The  to decrease  reason  relationship  i s p r e s u m a b l y t h e d e v e l o p m e n t o f Van d e r Waal  bonds by t h e l o n g c h a i n h y d r o c a r b o n s particles  (Appendix B ) .  still  i n solution  weaving around  r a t h e r than  colloidal  any i n t e r a c t i o n  b e t w e e n t h e s u r f a c t a n t i o n s among t h e m s e l v e s .  I n any e v e n t  53  the aggregates r e m o v a b l e by  a r e not s u r f a c e a c t i v e  and  consequently  flotation.  4.2.1.2 The  pH  4.6  flotation  process  under study d i s p l a y s i t s  most d r a m a t i c c h a n g e s a t pH  4.6.  i m p o r t a n t to understand  nature of those  the  they r e p r e s e n t the best source  Therefore, i t i s especially  fails  c o m p l e t e l y t o p r o d u c e any  light  brown f r o t h  d o s a g e t o 150  ppm  i s formed. produces  Immediately,  ment o f e i t h e r f r o t h In g e n e r a l , t h i s by t h e p r o c e s s  of the reamining  solution  A s u r f a c t a n t d o s a g e o f 200 few  process  incipient,  thick  scum i s f o r m e d  laden f r o t h .  100  ppm.  No  further  i n the  supported develop-  solution.  v e r y much t h e one  exhibited  N e v e r t h e l e s s , the  turbidity  i s c o n s i d e r a b l y h i g h e r a t pH ppm  produces,  d u r i n g the  b i g g e r and  ring  underneath  paler, f i n a l l y  acquiring  t h e h e a v y w h i t e foam p r o d u c e d in solution.  The  it.  by an  Next the r i n g  4.6.  first  seconds of the p r o c e s s , a c h o c o l a t e - c o l o r e d f r o t h  a cream-colored  ions  the  I n c r e a s i n g the s u r f a c t a n t  o r scum i s o b s e r v e d  3.6,  ppm,  scum; o n l y an  behavior resembles  a t pH  A t 100  the  s p e c t a c u l a r m o d i f i c a t i o n s i n the  a dark  by a h e a v y , s t a b l e , c o l o r  changes s i n c e  of i n f o r m a t i o n r e g a r d i n g  mechanisms i n v o l v e d i n the p r o c e s s .  process.  not  with  becomes  the c h a r a c t e r i s t i c s excess  of  of f r e e s u r f a c t a n t  i n c r e a s e i n the t u r b i d i t y  of  the  54  remaining it  solution  seems l o g i c a l  becomes q u i t e  noticeable.  At t h i s  t o c o n c l u d e f o r t h e pH u n d e r s t u d y  point,  that:  1.  A l t h o u g h the l a r g e r p e r c e n t a g e of the negatively charged chromophores are not a s s o c i a t e d , s t i l l a certain fraction o f them i s a t t a c h e d t o o t h e r chemical species in the solution.  2.  The a t t a c h e d m o i e t y o f the c h r o m o p h o r e s competes p r e f e r e n t i a l l y f o r the h y d r o p h o b i c c a t i o n , p r o b a b l y because of the p r e s e n c e of several n u c l e o p h i l i c g r o u p s in the aggregate, i.e. a higher intensity of negative charges. The c o m p l e x f o r m e d either is not s u r f a c e a c t i v e or i t is too s t r o n g l y bound to the b u l k o f the solution t o be s e p a r a b l e by f l o t a t i o n . For that r e a s o n , an a l m o s t e n t i r e lack of froth i s o b s e r v e d , as is an i n c r e a s e in the t u r b i d i t y of the s o l u t i o n .  3.  Once the c o n c e n t r a t i o n o f s u r f a c t a n t is i n c r e a s e d t o an o p t i m u m v a l u e w h e r e t h e interfering s p e c i e s are electrostatically s a t i s f i e d , the c o a g u l a t i o n reaction between the u n a t t a c h e d c h r o m o p h o r e s and the h y d r o p h o b i c c a t i o n takes p l a c e . The sublate is s u r f a c e a c t i v e and i s removed by f l o a t i o n in the form of a f r o t h with a c o a g u l a t e d s c u m on t o p .  k.  If the c o n c e n t r a t i o n of s u r f a c t a n t exceeds the optimum v a l u e , the h y d r o c a r b o n chains of the s u b l a t e b e g i n to a s s o c i a t e , a phenomenon a k i n to the f o r m a t i o n o f micelles i n a q u e o u s s o l u t i o n s and c a l l e d hemimicelles by G a u d i n a n d F u e r s t e n a u (62). The h e m i m i c e l l e s a r e not s u r f a c e a c t i v e . As the amount o f c o l l e c t o r is i n c r e a s e d , the percentage of f r e e ions a l s o i n c r e a s e s and c o n s e q u e n t l y the foaming p r o c e s s .  The most i m p o r t a n t o f t h e p r e v i o u s (number o n e ) i s b a s e d on a r e c e n t  publication  conclusions by Swanson  55  et  al.  (13).  mixture  These authors  of chromophores  c o l o r of the plausible  have p o i n t e d  explanation, that  "the  each chromophore i s d i f f e r e n t Figure  10,  bodies  were d i v i d e d i n t o  Regarding  the  weight, high and  pH,  degree of  4).  a c i d - s o l u b l e and  unconjugated  seem a s s o c i a t e d w i t h  that  through  a t 100  the  (Figure 9). flotation  as  i s of c o u r s e ,  Still,  at t h i s  the  recovery  specific  p r e s e n c e o f some n a t u r a l and  because the  Yet,  as  by  evidenced  there  the  of  are  "efficient"  the  w i t h i n the  solids"  ( 1 3 0 - 1 6 0 ppm).  floated  remains constant.  floated  b e c a u s e o f Van  replaced  by  the  At  200  character,  8  some s u r f a c t a n t  by  achieved  ppm  the  the  i n the e f f l u e n t  in solution  represents The  the  process  removed by  i s more flo-  amount o f p o s s i b l y f l o a t a b l e percentage of  free ions.  surfactant  fraction  interactions is  amount f l o a t e d as  by  completely  responses.  "the  ppm  that  f l o a t e d i s minimum  I t seems t h a t t h e  d e r Waal  6 and  amount o f s o l i d s  range of  molecular  amount o f s o l i d s f l o a t e d  150  process  falls  like  f r e e s u r f a c t a n t ions  l a c k of foam.  ( F i g u r e 7) and  have low  compounds."  r e a c t i o n i s not no  color  a c i d - i n s o l u b l e groups.  active species  optimum d o s a g e f o r a l l t h e  tation  (see  dosage i s p r o b a b l y  surface  coagulation  suppressed.  pH  Figures  solids  and,  of  values"  the a  ionization  "they  c o l o r l e s s carbon  t h e p e r c e n t a g e o f s u r f a c t a n t and ppm  s u g g e s t e d , as  C00H g r o u p s , l i g n i n  observed  Since  Furthermore, the  former i t i s remarked  be  they  at d i f f e r e n t  from r e f e r e n c e  I t can  presence of a  i n the waste water samples.  e f f l u e n t changes w i t h  taken  to the  not  fully  However,  the  56  figure  COLOR VERSUS pH MILL EFFLUENT  FOR  10.  TOTAL  3000  ^  2500  0)  c 3 O  O »  2000  o o °  1500  1000  '  I  2  4  I  I  6  8 pH  L  10  12  57  process  "efficiency"  understandable  s u f f e r s a marked d e c r e a s e .  s i n c e t h e amount o f s o l i d s  numerator i n the " e f f i c i e n c y " the  formation  easily  I t must teristics  i n Figure  The d r a s t i c  Herschmiller  c h a n g e i s more 8.  out t h a t the p e c u l i a r  e x h i b i t e d by t h e p r o c e s s  quite closely  floated (the  9 than i n F i g u r e  be p o i n t e d  t o t h e ones o b s e r v e d (4) i n d i f f e r e n t  at this  pH  aspects  by  o f h i s work.  4.2.1.3  pH  a dramatization  conclusions  a different  of the f l o t a t i o n  process  will  hold  in this  at i t s highest.  Moreover  factant  form i s c o n s i d e r a b l y  the expectable  A t dosages o f 100 and 150 ppm almost i n s i g n i f i c a n t ,  "efficiency"  The  the process  chromophores i s  fraction  only  light-brown  of sur(Figure 4).  produces a  froth.  very  same  only  l e s s a t this pH  centage of s u r f a c t a n t f l o a t e d increases 6 ) , the process  a t pH 5.6 i s  case w i t h  one m o d i f i c a t i o n ; t h e p e r c e n t a g e o f a t t a c h e d  sparse,  results  approach.  o f what happened a t pH 4.6.  made b e f o r e  in ionic  process  5.6  The b e h a v i o r only  using  Yet, the  and t h e  r e s p o n s e s were n o t t h e same i n h i s w o r k ; a l s o t h e were e x p l a i n e d  charac-  corresponds  and d e s c r i b e d  e f f l u e n t used, the set of conditions f i x e d  obtained  i s quite  t e r m ) i s h i g h l y a f f e c t e d by  of hemimieel 1es.  appreciated  This  The  little  and t h e p e r c e n t a g e o f  per-  (Figure solids  58  floated ppm,  remain almost c o n s t a n t .  well  ions. and  becomes b i g g e r  known f o a m i n g  It follows  process  will  p r o b a b l y be  nonfloatable  dosage w i l l removed by  there  that, although  the  r e s t of complex.  flotation.  .As  each i n c r e a s e  i s not  other  top  paler  a marked  represents  surfactant  increase  in solids floated  been s u d d e n l y a c h i e v e d ;  the  f o r the  chromophores are  Any  increase e f f e c t on  a r u l e , the  200  ring,  finally  to f r e e  an  hand, a t  o f a cream  and  optimum c o n d i t i o n s  c a u s e a deleterious  turbid with  and  p r o c e s s due  " e f f i c i e n c y " has  p r o c e s s s i n c e the the  the  a d a r k brown f r o t h i s f o r m e d on  which, again, the  On  coagulation attached  i n the the  this  to  surfactant  amount o f  solids  s o l u t i o n becomes more  i n the amount of  improvement a t the  surfactant  so-called  and  optimum  dosage.  4.2.2  Continuous  select  pH  Experiments  The  batch  3.6  and  e x p e r i m e n t s r e s u l t s made i t p o s s i b l e  100  ppm  best parameters f o r the aimed a t d i m i n i s h i n g kraft  the  preliminary be  D i f f e r e n t methods f o r m i x i n g i ) to feed  as  Further  amount o f  p o s i t i v e r e s u l t could  were t r i e d :  surfactant  process.  e f f l u e n t were c o m p l e t e l y Several  any  of  being batch  surfactant  unsuccessful trials achieved the  probably  liter  surfactant  both streams s e p a r a t e l y  the into  D).  before  continuous and  of  Appendix  were n e c e s s a r y i n the  the  experiments  per  (see  to  runs.  effluent the  59  flotation stream, iii)  c o l u m n , i i ) t o add  and  the s u r f a c t a n t to the  t h e n , the m i x t u r e , to the f l o t a t i o n  to s e t a s t i r r e d  they entered  premixing  stage f o r both  to the f l o t a t i o n  column.  r e s u l t s were o b t a i n e d w i t h t h e f i r s t also  two  effluent  column, streams  before  Practically,  procedures.  i m p o r t a n t t o keep t h e a i r f l o w r a t e s l o w  no  It  s i n c e the  was develop-  ment o f t u r b u l e n c e , a t h i g h e r v a l u e s , t o t a l l y  obviated  coagulation-flotation  the s u b l a t e .  process  Once t h e c o n t i n u o u s was  by r e d i s p e r s i n g e q u i p m e n t was  run u s i n g the b e s t batch parameters  times i n t h e c o l u m n .  The  results  ment. The  No  foam o r f r o t h was  treated  noticeable minutes due  t h e same as  has  e f f l u e n t was  a deleterious  to r e d i s s o l u t i o n  surfactant floated because a f r e s h  runs.  the c o r r e s p o n d i n g developed,  the p r o c e s s ,  not  involved.  used  dark  scum.  15  probably  percentage  h i g h e r i n the c o n t i n u o u s  b o t t l e o f t h e r e a g e n t was  s e q u e n t l y , a g e i n g was  experi-  It is clearly  time over  The  in  process  batch  colorless.  the f l o t a t i o n e f f e c t on  The  only a thick  of the p r e c i p i t a t e .  was  retention  ( T a b l e 5) a r e c o m p a r a b l e ,  virtually  that increasing  perfected, i t  but v a r i o u s  g e n e r a l , to t h o s e o b t a i n e d i n the b a t c h behaved e x a c t l y  the  run, and,  of  possibly con-  Table 5 Continuous  Flotation Time (mi n u t e s )  %  Surfactant Floated  Experiment  Results  Surfactant  and V a r i o u s  % Solids  Floated  O b t a i n e d a t pH 3.6, 100 ppm Retention  of  Times  Solids Floated Surfactant Floated  Solids Floated (ppm)  Temp. °C  8 8  98 6 95 0  15 06 18  1 .12 1 .42  110 133  25° 26°  15 15  98 6 94 8  15 06 17 5  1 .12 1 .35  no 128  25° 26°  30 30  94 48 94 5  12 62 15  0 .94 1 .17  93 111  25° 26°  45 45  98 22 94 3  11 57 12 0  0 .86 0 .94  85 89  25° 26°  CT)  o  61  4.3  Studies  on  the  I n f l u e n c e of  Elapsed  on  the  Kraft Mill  4.3.1  Total  the  nor  difference  solids  could  in their  types  the  12A)  b u t , on  the  the  adjusted  time,  marked  i.e. within present  (Figures 11-A,B,C,D).  absorption  spectra  the  (Figure 13).  remained  other  B,C). of  refrigerated, original the  chosen p e r i o d of  previously adjusted  Allowing  f o r the  i t could  practically  h a n d , a t pHs  a definite  ( F i g u r e 12  and  previously  e f f l u e n t showed any  with  during  samples w i t h  color value  seemed t o be  three  pHs  amount o f s o l i d s  to b a t c h  between each b a t c h ,  3.6,  storing  total  c o l o r of the  of behaviors.  differences  day  original content  remained u n a l t e r e d  ( F i g u r e 12D), two  their  Color W h i l e the  effluent  the  s i n c e the  change from b a t c h  4.3.2  Time  Waste  samples w i t h  to a c e r t a i n v a l u e ,  same b a t c h ,  A d j u s t m e n t and  S o l i d s Content  Neither  the  pH  o f 4.6  expectable be  al.  (13)  constant and  3,  6 and  24  5.6  7.6,  storage.  pH  there  the  seventh the  after  d a y s a t room  A marked d e c r e a s e i n c o l o r i s e v i d e n t  s i x days o f  color  (Figure  reported  k r a f t e f f l u e n t s , a t pH  s a m p l e s f o r 1,  displayed  said t h a t , at  decrease of c o l o r a f t e r  Swanson et  pH  time  temperature between  62  figure  11.  E F F E C T OF S T O R A G E TLViE A N D pH CM S O L ! DS C O N T E N T O F KRAFT MILL E F F L U E N T 0 , d , 0d i f f e r e n t b a t c h e s A  ^  0  i Op  A - O O o^  A  o  o  5  0 o o  10  B.  r  DH  4,5  o  ! 2 t h day) A  15  A  20  A  A  oo  0  o o  on  A  10  oh  c  (defrozen  *°  :  0  10  c.  10 r pH  5.6  o  o  o  F ° 0  o  0  15 D.  lOrno  pH  adjustment  r o ° o 0  O  o o o o o o 5  10  clays after  15 sampling  20  63  figure 12. EFFECT OF STORAGE ON COLOR OF K R A F T  A.  Filtered  1 5 r P H 3.6 O  101-  o  o  0  15rPH4.6  1  10h  1«  o o o  10  15  20  10  15  20  oo _J  +- 1 5 r p H 5.6 Q. v.  10h 5  A  •  C.  I  ^  • •  5  o o  A  .  '  B  AND pH EFFLUENT  0 , D , 0 different batches A = O (defrozen on 12th day)  at:  •  TIME MILL  ••  A  o ° o °  •  O  10  15  20  D. 15pno 1 0 h ° °  pH  o  adjustment  o  o  0  5 days  0  o  °  0  10 after  15 sampling  20  64  figure 13.  EFFECT OF STORAGE A N C E (at pH 7.6) O F WASTE  ON ABSORB UNTREATED  40 254 nm •A-  30 280 nm 0)  75 >  20  O C CO  €  O CO  4  n  (0  420 nm  1  1  10  15  time , days  •o  20  25  65  4.3.4  Filterability The f i l t r a t i o n  high  r a t e of the e f f l u e n t , which  i n a l k a l i n e medium becomes much s l o w e r a t l o w pH v a l u e s ,  especially  a t 3.6.  The p o s s i b i l i t y  i n s o l u b l e , chromophoric  aggregates  of the presence at this  change i n t h e f i l t r a t i o n "the c o l o r  bodies  rate.  become  Moggio  increasingly  lower  work.  The c o l o r  i n s o l u b l e a t low  filtration flotation  stage. process  I t i s also  the c o l o r  behind  noteworthy  solution  means t h a t most o f t h e c o l l o i d s (chromophoric during  ment w i t h t h e q u a l i t y for  pH 4.6  t h a t , once the the f a s t e s t  and c o l l o i d  Undoubtedly  of the r e s u l t a n t  the s o l u t i o n  the f i n a l  solution  and most o f i t s c o l o r  stage preceding  aggregates  from  filtration  turns.  This present  the s o l u t i o n  this  i s i n agree-  solution.  and 5.6, t h e h i g h e r t h e i n i t i a l  t h e more t u r b i d  filtration  process.  i t i s a fact  i s o b t a i n e d a t pH 3.6.  o r n o t ) have been removed  the f l o t a t i o n  readings  during the r e q u i r e d  has been a c c o m p l i s h e d ,  rate f o r the remaining  always  t h e pH has been a d j u s t e d a t  Therefore, although  has been l e f t  pHs."  phenomenon i n h i s  a r e t a k e n a t t h e same pH v a l u e f o r a l l s a m p l e s , t h a t some c o l o r  that  r e a d i n g s , as a r u l e , a r e  i n those samples i n which  lowest value.  neutral,  f o r t h e marked  (63) observed  Brown ( 6 4 ) has a l s o d e s c r i b e d a s i m i l a r experimental  of  pH has been men-  t i o n e d a l r e a d y and c o u l d p r o b a b l y be t h e c a u s e  its  i s quite  In g e n e r a l ,  amount o f s u r f a c t a n t The  turbidity  of  i s removed d u r i n g t h e  the c o l o r  test.  For t h a t  reason,  66  it  i s obvious that  surfactant  a complex, n o n - f l o a t a b l e by  filtration.  can  be,  Figure  i f t a k e n as  According  to  i t the  by  the  shows how  that  the  when t h e  and  of  ppm  Studies  the  process  presence of  conclusion  process behavior since  200  deceiving  is raised, regardless  Moreover, the  is obtained  4.4  14  the  flotation  bound  enough t o be  amount o f c o l o r removed  It follows  disclosed.  c o l o r bodies are  aggregate, big  a measure of  dosage of s u r f a c t a n t effluent.  and  the  in  removed  color  test  response. increases  of  the  pH  as of  the the  interaction is  reached  i s openly  "worst l o o k i n g "  parameters are  not  denied  effluent  s e t a t pH  5.6  surfactant.  on  the  Behavior of  Acidification-A! kalization  Kraft Mill  Waste i n  Various  Sequences  i) acid i f i c a t i o n - a l k a l i z a t i o n - a c i d i f i c a t i o n ii)  al kal iz a t i o n - a c i d i f i c a t i o n - a l kal i z a t i o n - a c i d i f i c a t i o n  A sample from E l k F a l l s in  these s t u d i e s .  mixing  proportional  the m i l l . this and used  This  was  The the  amounts o f  of  the  mixed  starting point.  concentrated (see  pH  total  mill the  total  mill  e f f l u e n t was four  e f f l u e n t was Concentrated  C).  used  obtained  main o u t l e t s  sodium h y d r o x i d e were the  Appendix  e f f l u e n t was  s e v e n and  from hence  hydrochloric a c i d and  by  acid  alkali  67  figure 14.  COLOR REMOVAL FROM KRAFT MILL EFFLUENT AS A FUNCTION OF A M O U N T O F S U R F A C T A N T ADDED A N D pH 100 90 80 70  -a  >  |  60  0)  50  8 0  h  40  s  30  PH  20  03.6  10  •  A 4 . 6  5.6  50 ppm  100 of surfactant  150 added  200  68  Figures the  15  e f f l u e n t i n the  Although tigated  and two  16  show t h e  aforementioned  kraft mill  trends  followed  during  the  is really  remarkable.  in Figure  17.  s t u d i e s were to g a i n waste a t the in  pHs  very  16,is  low  pH,  strong  acidification  the  The  e f f l u e n t has  the  pattern  any  further  i)  ii) iii)  information  not  both  these  of  be  the focussed  i n both  Figures,  been b r o u g h t t o a  ( i . e . c u r v e AB)  i s never  alkalization-acidification  From t h a t p o i n t o n ,  a l l the  behavior  feature  the  typical  a c i d n e u t r a l i z a t i o n curve i s always  Gathering  of  partially  discussion will  most s t r i k i n g  original  inves-  main o b j e c t i v e s of  some k n o w l e d g e o f t h e the  by  They d i d  r e s u l t s are  t h a t once t h e  reproduced during sequences.  (61)  agreement between  Their  Since  under s t u d y ,  that direction.  15 and  al.  c a u s t i c e x t r a c t i o n stage e f f l u e n t .  p e r f o r m a b a c k n e u t r a l i z a t i o n . The  reproduced  displayed  sequences r e s p e c t i v e l y .  f o r a d i f f e r e n t p u r p o s e , Prahacs et the  results  behavior  together,  strong  base-  obtained.  i t can  be  said  During the f i r s t a c i d i f i c a t i o n of t h e e f f l u e n t f r o m pH 7 t o 3, c e r t a i n chemical s p e c i e or species are irreversibly transformed, No n o t i c e a b l e p r e c i p i t a t e o r evolution i s observed,  gas  The c o l o r o f t h e s o l u t i o n i s l e f t u n a f f e c t e d by t h e c h a n g e s i n c e back a l k a l i z a t i o n r e s t o r e s the c o l o r , r e a d i n g to i t s f u l l i n i t i a l value.  that  69  figure  15.  B E H A V I O U R O F K R A F T M I L L E F F L U E N T IN THE S E Q U E N C E ACIDIFICATION • A L K A L I Z ATION-ACIDIFICATION 1 2 r  A-B  HCI — C - A - A ' m l NaOH A'-A-C m l HCI —  2.5  ml  2.0  1.5  1.0  A-B  .5 I  C-A-A'-^ 0 2.5  .2  .4  2.0  ± 1.5  i  i  1  .6 1.0  I  .8  i  I  i  I  1.0 1.2  0 -*-A A-C L  70  figure  16.  B E H A V I O U R O F K R A F T M I L L E F F L U E N T IN THE SEQUENCE ALKALIZATION • ACIDIFICATION • A L K A L I Z A T I O N -ACIDIFICATION  —{  71  figure 17,  ACIDIFICATION OF K R A F T C A U S T I C E X T R A C T I O N E F F L U E N T WITH 9 6 % H 2  SO4  O softwood 0.2  OA  0.6  0.8  1.0  1.2  v o l u m e of H S 0 r e q u i r e d , ' , m l / liter of e f f l u e n t 2  4  1.4  72  It are  has been s u g g e s t e d  originally  afterwards,  attached  of  some t y p e s o f s u g a r s  t o t h e c o l o r b o d i e s and r e l e a s e d ,  i n polymeric  Taking  that  f o r m a t c e r t a i n pH v a l u e s ( 1 3 ) .  i n t o a c c o u n t how c o m p l e x t h e  composition  t h e e f f l u e n t i s and how many p o s s i b l e i n t e r a c t i o n s c a n be  developed  between a l l t h e d i f f e r e n t s p e c i e s  present, i t  w o u l d be p r e s u m p t u o u s t o name t h e f a c t o r r e s p o n s i b l e f o r such a p e c u l i a r  behavior.  In a g r e e m e n t w i t h possible assists  the discussed  t h a t an i n c r e a s i n g c o n c e n t r a t i o n i n breaking  t h e bonds t h a t  chromophores t o t h e i r  associates  hold  4.5  t h a t moment,  species,.  closing this  d i s c u s s i o n , i t must be  pointed  t h a t t h e i n f l u e n c e o f c e r t a i n v a r i a b l e s was d e t e r m i n e d  during  several  sets of t e n t a t i v e batch  work c a r r i e d o u t by H e r s c h m i 1 1 e r  experiments.  (4) i n r e l a t i o n  specific  v a r i a b l e s was t a k e n as a good s t a r t i n g  For  r e a s o n t h o s e v a r i a b l e s were f i x e d  that  during tion  soluble  Other V a r i a b l e s o f I n t e r e s t Before  out  i t is  o f hydronium i o n  the acid  and, from  t h e y r e m a i n i n s o l u t i o n as i n d i v i d u a l  results,  the experimental  of narrowing  variables.  work.  the basic  They s h a l l  This  study  to these point.  at definite  was done w i t h  t o t h e most  be m e n t i o n e d  Previous  briefly:  values  the i n t e n -  important  73  Air the f l o t a t i o n rate  (1.66  flow  rate  and  process performed  c c / s e c ) and  Introduction  using  of  were o b t a i n e d d i s s o l v i n g and  introducing  s i z e - I t was  a fine porosity  the  surfactant  Premixing the s t i r r e r  and  speed  t i m e and  a stirrer  speed  a good c o m b i n a t i o n o f b o t h  Temperature temperatures  speed  the i o n f l o t a t i o n no s e n s i b l e kraft  process.  extraction  f r o m 20 t o 58°C.  ture  results  - The  The  RPM  effect  of pre-  seemed t o make  parameters.  f r o m 15°  (65) o b s e r v e d  t o 34°C do  P r a h a c s and  not  Wong ( 6 1 )  e x p e r i m e n t s d i s c u s s e d were temperature w i t h i n  that  affect found  removed  at temperatures  o b t a i n e d d i d n o t show any  dependence.  premixing  Five m i n u t e s  o f 950  effluent  o u t a l w a y s w i t h an e f f l u e n t The  (10).  change i n the p e r c e n t a g e o f c o l o r  caustic  Any  t o have a m a r k e d  - R u b i n and J o h n s o n  i n the range  methanol  i n a s i n g l e dose o r i n  stirrer  appeared  (4,65).  results  by a s y r i n g e .  on t h e f o r m a t i o n o f t h e p r e c i p i t a t e . mixing  i n 10 c c  i n v e r y poor r e s u l t s  time  best  that flow  disperser  - The  the s u r f a c t a n t  the s u r f a c t a n t  a powder f o r m r e s u l t e d  found  a t i t s b e s t a t low gas  i t at very slow r a t e s  a t t e m p t to i n t r o d u c e  t i m e and  sparger  from  varying carried  25-35°C.  significant  tempera-  Chapter 5  CONCLUSIONS  5.1  From t h e S t u d i e s 1.  flotation  The p e r c e n t a g e o f s u r f a c t a n t  i s an optimum a t pH v a l u e s  Outside t h i s associate  the  A t optimum pH v a l u e s  t h a n 72.5 ppm.  surfactant  ions  3.  varying  by  f r o m 3.6  t o 4.6.  ions to  evident  Nevertheless,  at  concentrations  the i n t e r a c t i o n o f i s not a c r i t i c a l  factor  process.  Under t h e b e s t c o n d i t i o n s , 9 0 % o f t h e s u r f a c t a n t  solution i s in ionic  form.  The r e s t i s p r o b a b l y  g a t e s t h a t m i g h t be r e a d i l y f o r m e d likely,  recovered  and i n a q u e o u s s o l u t i o n ,  among t h e m s e l v e s  in the c o l o r coagulation  in  Surfactant  i s maximum.  p r e s e n c e o f a g g r e g a t e s becomes  greater  of the  range, the tendency of the s u r f a c t a n t  2. the  on t h e F l o a t a b i l i t y  i n s o l u t i o n o r , more  due t o a g e i n g o f t h e s u r f a c t a n t .  74  aggre-  75  4. factant  of i t s aggregates  nique s t i l l  needs f u r t h e r  Batch 1.  surfactant  flotation assumed  This  the tech-  improvement.  Process  Experiments the presence  of  signifi-  b e t w e e n t h e pH o f t h e w a s t e and t h e amount  added.  Consequently,  the behavior of the  p r o c e s s d e p e n d s e n t i r e l y on t h e c o m b i n e d v a l u e s  by t h e s e  2. of  i n aqueous s o l u t i o n .  I t has been d i s c l o s e d  cant i n t e r a c t i o n  of sur-  as a means t o d e t e r m i n e  From t h e S t u d i e s on t h e F l o t a t i o n 5.2.1  of  t o use t h e p e r c e n t a g e  r e c o v e r e d by f l o t a t i o n  presence  5.2  I t i s possible  surfactant  the s t u d i e d  variables.  I t i s possible  to s e l e c t  as t h e b e s t p a r a m e t e r s ranges.  pH 3.6  and 100  f o r the process  At these conditions  i t was  within  observed  that: a ) t h e amount o f s o l i d s t h a t c o u l d be p o s s i b l y f l o a t e d v a r i e d f r o m 130160 ppm, b) t h e p r o c e s s r e s p o n s e s w e r e a t t h e i r b e s t v a l u e s , i . e . 90% s u r f a c t a n t f l o a t e d , 1.57 r a t i o o f s o l i d s f l o a t e d t o s u r f a c t a n t f l o a t e d and 21.5 o f total solids floated, c) the r e p r o d u c i b i l i t y o f the r e s u l t s was h i g h l y s a t i s f a c t o r y ,  ppm  76  d) two s i m u l t a n e o u s take p l a c e :  processes  seemed t o  i ) a g g r e g a t i o n of the a c i d chromophores, ii)  insoluble  an i n s t a n t a n e o u s c o a g u l a t i o n r e a c t i o n between t h e a c i d - s o l u b l e , n e g a t i v e l y charged chromophores and t h e c a t i o n i c s u r f a c t a n t i o n  e) t h e c o m p l e x s p e c i e s f o r m e d by t h e d e s c r i b e d p r o c e s s e s were i m m e d i a t e l y removed by f l o t a t i o n i n t h e f o r m o f a d a r k , t h i c k scum. Neither froth n o r foam was p r e s e n t . In general b o t h a p p e a r e d t o be r e l a t e d w i t h an i n e f f i c i e n t performance of the p r o c e s s .  3. to  The  flotation  p r o c e s s was  found  t o be  a i r f l o w r a t e , s p a r g e r s i z e , means o f i n t r o d u c i n g  s u r f a c t a n t , s t i r r e r speed significant  temperature  and  premixing time.  d e p e n d e n c e was  found  sensitive the  However,  no  i n the range  of  25 t o 35°C.  5.2.2  Continuous 1.  floation  The  p o s s i b i l i t y of r u n n i n g the c o a g u l a t i o n -  p r o c e s s c o n t i n u o u s l y has  2.  The  process  runs are comparable batch  Experiments  experiments.  been f u l l y  b e h a v i o r and  results  demonstrated.  of the  continuous  to those o b t a i n e d at the c o r r e s p o n d i n g  77  3. requires achieve  The  mixing  a separate positive  4.  stirred  premixing  The  m i n u t e s has  flotation-coagulation  An  process  i n c r e a s e of the f l o t a t i o n  a d e l e t e r i o u s e f f e c t on  by r e d i s p e r s -  5.3  the E f f l u e n t  From t h e S t u d i e s on 1.  s a m p l e , no  During  color  readings  i s preceded  are being  the c o l o r the  duced  total  by  increases  test  affected  adjustment,  solids  content  to the  the  v i a the f i l t r a t i o n  of time  effects  been p r o v e n  a t pHs  the  4.6  chemicals  besides  results.  added.  the  Yet, final  stage. and  inaccuracy  no m a r k e d d i f f e r e n c e was  adjustment,  original  been d e t e c t e d .  for expressing f l o t a t i o n  s t o r a g e o r pH due  Behavior  has  by a pH  F o r t h a t r e a s o n , i t has  fifteen  presumably  the s t o r a g e of the r e f r i g e r a t e d  T h e r e i s a l s o some e v i d e n c e 5.6.  above  precipitate.  s e n s i b l e change i n c o l o r  the c o l o r t e s t  time  the p r o c e s s ,  of the  ing  to  development of t u r b u l e n c e at high a i r f l o w  because of r e d i s s o l u t i o n  of  in order  the s u b l a t e .  5.  if  stage  effluent  results.  r a t e s o b v i a t e s the ing  o f t h e s u r f a c t a n t and  normal  Regardintro-  78  2.  During  the a c i d i f i c a t i o n  pH 7 t o 3 c e r t a i n c h e m i c a l transformed.  The  I t i s suggested from t h e i r behavior.  specie  t r u e mechanism  of the e f f l u e n t from  or species involved  are  i s n o t known.  the r e l e a s i n g of the a c i d s o l u b l e  associates  as p a r t i a l l y  irreversibly  responsible  chromophores  f o r such  Chapter  6  FURTHER WORK  The p r e s e n t work has p r o v e n continuous color at  coagulation-floation  bodies  from  p r o c e s s f o r removing  effluents.  factant.  the  Yet the p r o c e s s ,  t e c h n i q u e s due t o t h e h i g h c o s t o f t h e s u r -  Therefore, further  industrial  following  studies are required regarding  possibilities.  f u t u r e work u n d e r t a k e n  I t i s suggested  in this  process  t h a t any  s h o u l d have t h e  aims:  1.  To m o d i f y  the process  using dispersed or  e n t r a i n e d a i r as t h e a e r a t i o n s o u r c e . t h e use o f f i n e  2.  recycle.  T h i s would e l i m i n a t e  s p a r g e r n o z z l e s and i t s c o n s e q u e n t l y  Either  to f i n d  s u r f a c t a n t or to develop its  of a  i t s present s t a g e , i s not c o m m e r c i a l l y c o m p e t i t i v e w i t h  o t h e r proposed  its  kraft mill  the f e a s i b i l i t y  A suggested  a cheaper  a n d / o r more  plugging.  efficient  a s u r f a c t a n t recovery process f o r r e c o v e r y p r o c e s s w o u l d be t o  79  80  dissolve should  the colored  sublate  in a caustic solution.  b r e a k up t h e s u r f a c t a n t - c h r o m o p h o r e c o m p l e x  This leaving  a q u a t e r n a r y ammonium h y d r o x i d e and a s o l u b l e c o l o r  compound.  The  extracted  quaternary  from t h i s and  alkaline solution.  removal  ever,  of the solvent  the described  of educated  3. since  ammonium h y d r o x i d e c o u l d  be s o l v e n t  Acidification  of the e x t r a c t  would complete t h e system.  recovery  process  i s purely  How-  i n the realm  speculation.  To d e t e r m i n e t h e t o x i c i t y  i t i s n o t known how t h e r e m a i n i n g  of the clear e f f l u e n t surfactant  contributes  to i t .  4. before  To c h a r a c t e r i z e  and a f t e r t h e t r e a t m e n t  understanding of the involved  the k r a f t e f f l u e n t c o l o r i n order  to gain  mechanisms.  bodies  a better  REFERENCES  H a r g e r , J . R . E . et al. 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Concepts in the Design of R i n e h a r t and W i n s t o n , 1 9 7 3 .  i n d . E n g . Chem., A n a l .  1944. 71.  Regression I n c . , 1968.  S t e v e n i n c k , J . Van and M. M a s s .  E d . 1_5: 4 9 2 -  E d . 1 6: 7 3 9 , ~~  R e c . T r a v . C h i m . 84_:  1166, 1965. 72.  C r o s s , J.T.  73.  C u l l u m , D.C. I n t e r n . Congr. S u r f a c e A c t i v i t y , P r o c . 3 r d , C o l o g n e , 3: 4 2 , 1 9 6 0 . Standard Methods for Examination of Water and Waste Water, 1 2 t h e d . , A m e r i c a n P u b l i c H e a l t h A s s o c i a t i o n , I n c . , New Y o r k , 1 9 6 5 .  74.  A n a l y s t 90 ( 1 0 7 1 ) : 3 1 5 - 3 2 4 , 1 9 6 5 .  APPENDIX A  ANALYSIS OF VARIANCE OF THE DESIGNED SET  OF  BATCH EXPERIMENTS  A.l  General A.1.1  factor  present  Experiments  general  of a two-factor  t i o n s , the tions  (66,67)  Two-factor To  variance  Review  formulas  experiment using  case of n r e p l i c a t i o n s of  determined B will  be  considered.  l e v e l s o f f a c t o r A and  of f a c t o r  B.  the a r r a y .  The  ith  level  the  abn  Thus t h e r e  are  Denoting  shown i n t h e  The  treatment  combina-  random s a m p l e o f s i z e  may  rows  columns r e p r e s e n t defines  c e l l s , each c e l l  kth o b s e r v a t i o n  following  observations  b levels  i n w h i c h the  the j t h l e v e l  i n the  of  be  classified  represent the  levels  a cell  in  containing  taken  of f a c t o r  at  n  the  B by  y^^^,  table. (ij)th  n from a p o p u l a t i o n  87  of  observa-  observations  combination  ab  the  o f f a c t o r A and  are  the  Each t r e a t m e n t  observations.  the  analysis  repeated  by a l e v e l s o f f a c t o r A and  by means o f a r e c t a n g u l a r a r r a y the  f o r the  cell  constitute  t h a t i s assumed  a  88  Table Al Two-Factor  Experiment with n  Replications  B A 1  1 l 1 1  y  y  l 12 • • •  ^1 In 2  o  • •  9  9  y  l bl  y  l b2  21 2  y  22 1 222  9  e  • •  9  y  2bl  y  2b2 9  • •  •  9 9  all  y  al 2  22n  •  •  •  •  T  al n  -l.  y2 • •  9 9 9  a22  y  2-.  9  a21  y  T  2bn  y  • • • •  • • • •  i - -  i bn  y  •  y  T  Mean  •  •  21 n  Total  a  l 2n  y  y  y  Mean  •  b  0  • • •  y  y  Total  1 22  y  21 1  y  • • a  l21  y  y  • •  • • •  2  • • • •  9 y  9  y  abl  T  a • •  ab2  •  y  a2n  T  -2.  y. . 2  •  • 9 y  • • • •  9  9  abn  T . •b • y . b.  .T 9 9 9  y J  a •°  to All  be n o r m a l l y  distributed  db p o p u l a t i o n s  w i t h mean y . . and v a r i a n c e a  a r e assumed  t o have t h e same  2  variance  .  90  where:  T.. *  =  sum o f t h e o b s e r v a t i o n s (ij)th cell  i n the  T.  =  sum o f t h e o b s e r v a t i o n s level of factor A  f o r the i t h  =  sum o f t h e o b s e r v a t i o n s level of factor B  f o r the j t h  1 J  T . * * >  J  sum v.. *  =  . * *  i n the ( i j ) t h  mean o f t h e o b s e r v a t i o n s level of factor A  f o r the i t h  =  mean o f t h e o b s e r v a t i o n s 1evel o f f a c t o r B  f o rthe j t h  =  mean o f a l l a Z m  J  y  A.l.2  observations  mean o f t h e o b s e r v a t i o n s cell  1 J  y  o f a l l abn  observations  Two-Factor A n a l y s i s o f Variance The g e n e r a l  y  ijk  =  u  +  model  a  i  +  6  f o r a two-factor  j  +  (  a  3  )  i j  +  e  ijk  experiment i s  where:  e  iik  m  e  y  a  s  u  r  ijk  e  v  the deviations  s  a  ^  u  e  s  i n  t  n  of the observed  ("i J ) t h c e l l  e  from t h e  p o p u l a t i o n mean u - - . (c*3).. 1 J  denote the i n t e r a c t i o n e f f e c t o f the i t h l e v e l o f f a c t o r A and t h e j t h level of factor B  a.j t h e e f f e c t o f t h e i t h l e v e l o f f a c t o r A  3.  the e f f e c t of the j t h l e v e l of f a c t o r  u overall The  following  f i=l  The  mean  r e s t r i c t i o n s a r e i m p o s e d on t h e g e n e r a l  a. = 0 , 1  I 3, = 0 , f (a6).. j = l i=l J  three hypotheses i)  H^: H|:  ii)  B  H'':  J  = 0 , J (a3).. j=l J  t o be t e s t e d a r e : a  1  = a  2  =  ,  * * a  A  = 0  a t l e a s t one o f t h e ct.'s i s n o t equal to zero  3  X  = 3  2  = •..  3.  = 0  a t l e a s t one o f t h e B.'s i s n o t equal to zero  model  = 0  92  iii)  = (a3)  = ...  H  0  :  (aB)n  H  x  :  a t l e a s t one o f t h e not equal to z e r o  1 2  (a3)  a D  = 0  (a6) . . 's i s J  Table A2 Analysis  o f V a r i a n c e f o r the Two-Factor with  Source of Variation Main  Sum o f Squares  Degrees o f Freedom  n  Experiment  Replications  Mean Square  Computed f  SSA " (a-1)  f  Tabulated F of s i g n i f i c a n c e  a = level  Effects A  SSA  (a-1)  B  SSB  (b-1)  „2 S  >  -2 S  2  SSB - (b-1)  2  - Si  fl  "  f  _ s " F"  F  a  == [ ( a - 1 ) ,  ab(n-lj]  =• [ ( b - 1 ) ,  ab(n-l)]  2  f  2  2  2  F a  Interaction AB  SS(AB)  (a-D(b-l)  Error  SSE  ab(n-l)  TOTAL  SST  abn-1  „2 _ 3 " s  „2 s  SS(AB) (a-l)(b-l)  2  F a  == [ ( a - l ) ( b - l ) , a b ( n - l )  _ SSE " ab(n-l)  CO  94  The structing  sum  of squares  the f o l l o w i n g  a r e u s u a l l y o b t a i n e d by  t a b l e of  totals.  Table Total  f o r t h e Sum  con-  A3  of the  Observations  B 1  A 1  T  l l .  2  T  2,.  2 !2.  T  • •  • •  •  •  •  9  o  •  a Total  T  T  •  •  •  •  •  •  •  •  •  b T  lb-  T  2b-  9 9  T  a2»  - l .  T  -2.  •  9  •  o  2-.  T  o «  T .  T  T .  T  ab •  • 9  ...  o  a  al-  T  o  o  9  Total  •b•  a ••  9 9 9  and  using the f o l l o w i n g  a SST  =  y  . , i=l L  computational  b y  . , j= 1 L  formulas:  n y  ,," k=1 L  T  v*  ijk  -  -vn  abn  a I  95  SSA = —  2  T j1  •_i  *'  bn  I  2  abn  T . 2  T  2  SSB = -L^ an  y  y  i..  abn  I T .  SS(AB) = l i L ^ J  i^J  A. 2  Tabulated A. 2 . 1  - SSA  T .  T2 +  1=J bn  SSE = SST  y  an  abn  - SSB - S S ( A B )  Analysis of Variance  and Sample C a l c u l a t i o n s  Analysis of Variance f o r % Surfactant Floated, pH and Amount o f S u r f a c t a n t Added A.2.1.1  Tabulated  Data  96  T a b l e A4 Tabulated  Data f o r % S u r f a c t a n t of S u r f a c t a n t  F l o a t e d , pH and Amount Added  pH Amount o f Surfactant A d d e d , ppm  3.6 ( b i )  4.6 ( b ) 2  5.6 ( b ) 3  (ax) 100  90. 90.38  30. 17.  27. 24.5  80.33 87.33  67.66 70.66  24.66 6.66  81.25 81.  75. 51 .  25. 32.  (a ) a  150  (a,)  200  97 A.2.1.2  Table of Totals T a b l e A5  Total  f o r t h e Sum o f t h e O b s e r v a t i o n s f o r % Floated,  pH and Amount o f S u r f a c t a n t  Surfactant  Added  pH Amount o f Surfactant A d d e d , ppm  100  3.6 ( b i )  180.38  4.6 ( b ) 2  47.  5.6 ( b ) 3  Total  51.5  278.88  (a ) 2  150  167.66  138.32  31.32  337.30  200  162.25  126.  57.00  345.25  TOTAL  510.29  311.32  139.82  961.43  (a,)  98  A.2.1.3  Analysis  of Variance  Table Analysis  A6  of Variance f o r % Surfactant  pH and Amount o f S u r f a c t a n t  Source of Variation  Sum o f Squares  Degrees Mean of Square Freedom  Floated,  Added  Computed f  Tabulated F a = level of significance  Main Effects  Amount o f Surfactant Added  437.83  2  pH  1 1 ,458.29  2  Interaction  2,286.97  4  Error  571.21  9  TOTAL  14,754.30  17  218.92 s  2  = 3.449 F ( 2 , 9 , . 9 5 ) = 4. 26  5729.14 s* = 90.26  571 .74 s  63.47  2  =  F ( 2 , 9 , . 9 9 ) = 8. 02  9.00 F ( 4 , 9 , . 9 9 ) = 6. 42  99  A.2.2  Analysis  of Variance f o r Ratio  of S o l i d s  Surfactant  F l o a t e d , pH and Amount o f  Surfactant  Added  A.2.2.1  Tabulated  Data  . Table Tabulated  Floated/  A7  Data f o r R a t i o  of Solids  pH and Amount o f S u r f a c t a n t  Floated,  Added  PH Amount o f Surfactant A d d e d , ppm  3.6 ( b i )  4.6 ( b )  5.6 ( b )  1 .47 1 .67  0.80 1 .24  0.185 0.53  0.875 1 .34  1 .36 1 .25  0.16 0.53  0.97 0.802  0.64 0.94  0.88 1 .78  2  3  Ui)  100  (a ) 2  150  (a ) 3  200  100  A.2.2.2  Table of Totals  Table Total  A8  f o r t h e Sum o f t h e O b s e r v a t i o n s f o r R a t i o o f S o l i d s  Floated/Surfactant  F l o a t e d , pH & Amount o f S u r f a c t a n t  Added  pH Amount o f Surfactant A d d e d , ppm  3.6 ( b i )  4.6 ( b )  5.6 ( b )  3.14  2.04  0.715  5.895  2.21  2.61  0.69  5.51  200  1 .77  1 .58  2.66  6.01  TOTAL  7.12  6.23  4.065  17.415  2  3  Total  (ai)  100 (a*)  150 (a.)  101  A.2.2.3  Analysis  of Variance  T a b l e A9 Analysis  of Variance f o r % Solids  pH and Amount o f S u r f a c t a n t  Source of Variation  Sum of Squares  Degrees Mean of Freedom S q u a r e  Floated,  Added  Computed f  Tabulated F a = level of significance  Main Effects  Amount o f Surfactant Added  0.02  2  0.01  s\  pH  0.82  2  0.41  s\ =  Interaction  2.08  4  0.52  S3  0.766  9  0.085  Error TOTAL  3.686  17  = 0.117 F ( 2 , 9 , . 9 5 ) = 4. 26  4.82  F ( 2 , 9 , . 9 5 ) = 4. 26  = 6.12  F ( 4 , 9 , . 9 5 ) = 3. 63 F ( 4 , 9 , . 9 9 ) = 6. 42  102 A.2.3  Analysis  of Variance f o r % Solids  Amount o f S u r f a c t a n t A.2.3.1  Tabulated  Floated,  pH and  Added  Data  T a b l e A10 Tabulated  Data f o r % S o l i d s F l o a t e d , Amount o f S u r f a c t a n t  pH and  Added  pH Amount o f Surfactant A d d e d , ppm  4.6 ( b )  5.6 ( b )  3.41 4.0  0.58 1 .78  21 .65 20.80  15.66 17.25  0.71 0.819  20.08 19:11  13.23 18.23  3.6 ( b i )  2  3  (ax) 100  (a ) 2  150  24.26 20.49 ~}i :  (a ) 3  200  17.52 11.27  103  A.2.3.2  Table of Totals  Table A l l Total  f o r t h e Sum o f t h e O b s e r v a t i o n s f o r % Floated,  pH and Amount o f S u r f a c t a n t  Surfactant  Added  pH Amount o f Surfactant A d d e d , ppm  3.6 ( b - i )  4.6 ( b )  5.6 ( b )  Total  44.75  7.41  2.36  54.52  42.45  32.91  1 .53  76.89  39.19  31.46  28.79  99.44  126.39  71 .78  32.68  230.85  2  3  (ai) 100 (a ) 2  150 (a.) 200 TOTAL  1 04  A.2.3.3  Analysis  of Variance  Table Analysis  A12  of Variance f o r % Solids  pH and Amount o f S u r f a c t a n t  Source of Variation  Sum o f Squares  Degrees Mean of Square Freedom  Floated,  Added  Computed f  Tabulated F a = level of significance  Main Effects  Amount o f Surfactant Added  168.15  2  pH  738.48  2  369.24 s  z  = 78.89 F ( 2 , 9 , . 9 9 ) =  8.02  Interaction  285.17  4  71 .29 s  3  = 15.23 F ( 2 , 9 , . 9 9 ) =  6.42  Error  42.12  9  TOTAL  1233.92  17  84.07 s\ = 17.96 F ( 2 , 9 , . 9 9 ) =  z  2  4.68  8.02  105  A.2.4  Sample  Calculation  The r e q u i r e d using of  be i l l u s t r a t e d  by  t h e d a t a o b t a i n e d f r o m % s o l i d s f l o a t e d , pH and amount  surfactant  added.  SST = 24 . 2 6  2  + 20.49  2  1 5.66  2  + 1 7.2 5  2  0. 71  2  CCA  calculations shall  - 54.52  + 0.81.9  2  + 76.89  2  + 21.65 + 13.23  + 17 . 5 2  + 99.44  2  SSA = 3128.80  - 2960.65 =  CCR _ 1 2 6 . 3 9 SSB  + 71.78  2  2  2  + 20.80 + 20.08 +19.11 + 3 . 4 1  2  2  + 18.23  2  + 11 .27  2  + 0.58  2  - (  (230.85)  2  2  3  0  ^  8  + 1 .78  2  )  5  2  2  + 4  2  +  +  2  2  168.15  + 32.68  (230.85) 18  2  g  SSB = 3699.13 - 2960.65  2  2  2  =738.48  _ 4 4 . 7 5 + 4 2 . 4 5 + 3 9 . 1 9 + 7.41 + 3 2 . 9 1 +31 . 4 6 + 2 . 36 +1 .53 +28.79* 2 2  - 3128.80  2  2  - 3699.13 +  2  2960.65  2  2  2  SSAB = 4152.45 - 3128.80 - 3699.13 + 2960.65 = 285  SSE = 1233.92 - 168.15 - 738.48 - 285.17 = 42.07  MSA =  1  6  8  :  1  5  = 84.07  MSB =  7  3  8  A  4  8  = 369.24  MSAB = 2 8 5 J 7 .  MSE =  4 2  ;  1 2  =  7  S  i " "OS.-,  2 _ 369.24 _ 2 4768 "  S s  "  2  = 4.68  2 _ 84.07 _ ,  S  U  4.68 "  7  1 7  ? f t 7 8  Q f i  -  9 6  R  '  q 8 9  g  107  A.2.5  Conclusions Since  action  i n the three sets of data  b e t w e e n t h e two f a c t o r s ,  of i n t e r a c t i o n analyzed  i t i s not s e n s i b l e to  i n f e r e n c e s on t h e m a i n e f f e c t s c o u l d mask them.  observing  inter-  i . e . pH and amount o f s u r -  f a c t a n t added, i s h i g h l y s i g n i f i c a n t , a t t e m p t t o draw  studied the  f o r the presence  I n s t e a d , the data  should  t h e i n f l u e n c e o f each f a c t o r a t f i x e d  l e v e l s of the other.  be  APPENDIX B  REGRESSION ANALYSIS  APPLIED AT  B.l  General B.l.l  THE  DATA  OBTAINED  3.6  Review (68) Linear  Regression  The method in  PH  TO  of l e a s t squares  was  applied  to the data  an a t t e m p t  to o b t a i n  a straight-line relationship  the v a r i a b l e s  presently  under s t u d y .  The f o r m u l a e  used  y = 3o + S i * + e, were t h e  1)  y = b  0  + bix  Z  3)  following:  b.-iim  2)  b  0  f o r a regression  predictive  model  (S x . ) ( Z y.)  x  = y - bix  108  model  between  of the type  (z S S  TOTAL  =  I A  S3 REGRESSION  S S  TOTAL  2  S S  "  s  _ "  p h  R  2  S S  S S  =  fl«,  REGRESSION  R E S I DUAL (n -2)  2  REGRESSION SS  f  TOTAL  2  n  R E G R E S S ION S  S S =  =  -  y )  >  +  S S  t  ^  -j ^ ^ ) x  2  RESIDUAL  110  where:  y = dependent  or random v a r i a b l e  x = independent or f i x e d v a r i a b l e So>  3 i = parameters of the r e g r e s s i o n model  y = p r e d i c t e d v a l u e of y f o r a g i v e n x b , b i = estimates of 3 » observations 0  0  3 i based on the  e = y - y = r e s i d u a l d i f f e r e n c e between the a c t u a l o b s e r v a t i o n f o r a g i v e n x and the corresponding f i t t e d value obtained by use o f the f i t t e d r e g r e s s i o n e q u a t i o n n = number of o b s e r v a t i o n s SS  T n T / i |  = Sum  REGRESSION  ^RESIDUAL  s  R  2  2  SE  =  of squares about the mean = Sum ^  u m  °^  o f squares due to r e g r e s s i o n s c  l  u a r e s  about r e g r e s s i o n  = mean square about r e g r e s s i o n , i t p r o v i d e s an e s t i m a t e based on n - 2 degrees o f freedom o f the v a r i a n c e about the r e g r e s s i o n , 6 = c o e f f i c i e n t of d e t e r m i n a t i o n , i t r e p r e s e n t s the p e r c e n t a g e of the v a r i a t i o n i n the data which i s e x p l a i n e d by the r e g r e s s i o n e q u a t i o n . = /s  7  = s t a n d a r d e r r o r o f e s t i m a t e , i t means t h a t the band around^the r e g r e s s i o n s u r f a c e computed as y. ± S E a p p r o x i m a t e l y i n c l u d e s 68% of the o b s e r v a t i o n used to e s t i m a t e the regression coefficients (b ,bi) E  0  2  Ill  B.l.2  Examining B.l.2.1  L a c k o f F i t and  The amount due  the R e g r e s s i o n  sum  of squares  to the v a r i a t i o n  g i v e n v a l u e s o f x , and called  Pure E r r o r residual  from  another  repeated  can  The  hypotheses ments on table.  The  computations  i n a r e g r e s s i o n problem the response  The  may  into  be  i s normally  first  component,  mere random  brought  varia-  component about  required for  with repeated  s u m m a r i z e d as  by  testing  measure-  shown i n t h e  c o m p u t e d f v a l u e s a r e c o m p a r e d w i t h t h e 100  respectively,  (1 -  a)  - 2, n - k )  % p o i n t o f t h e t a b u l a t e d F ( 1 , n - 2) o r F ( k distribution  the  within  e r r o r ; w h i l e the second  a measure of the s y s t e m a t i c v a r i a t i o n terms.  broken  component w h i c h  points, reflects  t i o n or pure experimental  higher order  be  between the v a l u e o f y  the l a c k o f f i t c o n t r i b u t i o n .  calculated  is  Equation  i n order to determine  the  relative  s i g n i f i c a n c e of the r a t i o t e s t e d .  B - l .2.2  P l o t of  Residuals  In p e r f o r m i n g tions  the r e g r e s s i o n a n a l y s i s  certain  a b o u t t h e e r r o r s a r e made, i . e . t h e e r r o r s a r e  assump-  indepen-  d e n t , h a v e z e r o mean, a c o n s t a n t v a r i a n c e , a ,  and  normal  is correct,  2  distribution.  the r e s i d u a l s  should  Thus i f t h e f i t t e d exhibit  tendencies  model  t h a t tend  follow  to  a  confirm  Table Bl Analysis o f Variance  Source o f Variation  Lack o f fit S S  TOTAL  SSS  n - 2  ^ R E S I D U A L  k - 2  RESIDUAL~  S S  PURE  -  4-  ERROR  n - k S S  PURE  ERROR  SS TOTAL  Mean  Square  Computed f  S S  1  ^REGRESSION  Resi dual  Pure error  Degrees o f Freedom  Sum o f S q u a r e s  Regression  f o r R e p e a t e d M e a s u r e m e n t s on t h e R e s p o n s e  S  S  REGRESS10N  S S  REGRESSION S*  RESIDUAL  n - 2  S S  RESIDUAL"  S S  PURE  k - 2  _ s  e  2  S S  PURE  n - 1  where n = number o f o b s e r v a t i o n s u s i n g k d i s t i n c t v a l u e s o f x .  ERROR  ERROR  n - k  S S  RES1DUAL"  s  2 e  (k  S S  PURE  - 2)  ERROR  113  the of  a s s u m p t i o n s made, o r the  graphical.  b e s t and In  the  any  action. i)  In  indicate  the  and  the  v i o l a t i o n s of  corrective  way  corresponding  more i n f o r m a t i v e ,  reveal  easiest  to  practical regression  examination of  will  l e a s t , should  not  exhibit a  denial  assumptions. The  far  at  The  examine the  situations  residual  plots will  plots almost  assumptions serious most common p l o t s  time sequence, i f the  whether a long-term  a  of  residuals  is  detailed is  usually  certainly  enough t o  require  residuals  are:  o r d e r i s known.  time e f f e c t  is  This  influencing  data. ii)  A g a i n s t the  independent v a r i a b l e s .  This  will  reveal:  x not : r  a)  the  b)  error  the  variance,  in calculation, i.e. linear effect  of  removed, v  c)  need f o r e x t r a  term i n x i n the . the  constancy of  avoid  the  use  of  the the  actual  predictive  Regarding  predictive  that  the  in general  v a l u e o f y.  model.  x range, i . e . f o r e x t r a p o l a t i n g  stated  quadratic  model.  i i i ) A g a i n s t the a c c u r a c y of  t e r m s , f o r example a  C a r e must be  model o u t s i d e  the  test  taken  to  explored  purposes.  independence of regression  This w i l l  the  situations  errors, the  i t has  effect  of  been  114  correlation  b e t w e e n r e s i d u a l s need n o t be c o n s i d e r e d  a r e made, e x c e p t when t h e r a t i o in  residuals/number  B.2  Tabulated  when p l o t s  number o f d e g r e e s o f f r e e d o m  of r e s i d u a l s i s quite small.  Analysis of Variance,  S a m p l e C a l c u l a t i o n and  Plot of Residuals B.2.1  Analysis of Variance  f o r % Surfactant  Floated  vs Amount o f S u r f a c t a n t Added a t pH 3.6  T a b l e B2 Analysis of Variance  f o r % Surfactant  F l o a t e d v s Amount  o f S u r f a c t a n t Added a t pH 3.6 Source of Variation  Sum o f D e g r e e s o f Squares Freedom  Regression  120.50  1  33.60  5  Residual  Lack o f fit  Mean Square  5 [ 6.5  ~ 6  4  TOTAL  154.1  6  F(1,5.99) = 16.26  7 2  6.77(3-2) ^ = 6 . 5  [27.1  = 17.93  r -in  1  Pure error  If^f  120.5  33.6  Tabulated F  Computed f  °*  9 6  F(l,4,.99) = 21.20  115  B.2.2  Analysis of Variance f o r Ratio of S o l i d s Surfactant  Floated  Floated/  vs Amount o f S u r f a c t a n t  Added a t pH 3.6  T a b l e B3 Analysis  of Variance f o r Ratio  Floated  Source of Variation  of S o l i d s  Floated/Surfactant  v s Amount o f S u r f a c t a n t Added a t pH 3.6  Sum o f Degrees o f Squares Freedom  Regression  0.69  Residual  0.20  Lack o f fit  0.03  Pure error  0.17  TOTAL  0.89  Mean Square  0.69  0.02  Computed f  0.69 = 17.25 0.04  F(l,5.99) = 16.26  = 0.04  0.03 0.03 _ = 0.03 1 0.042(3-2)-  0.17  Tabu!ated F  = 0.042  n i n r a 7 D 5  F(l,4,.99) = 21.20  116  B.2.3  Analysis  of Variance f o r % Solids  Amount o f S u r f a c t a n t  Table Analysis  Surfactant  Regression  6.37  1  Residual  11 .93  5  TOTAL  18.30  6  B.2.4  Sample  the data obtained  floated/surfactant pH  Mean Square  6.37  vs Amount  3.6  Computed  2.39  "  2  Tabulated F F ( l ,5.99) = 16.26  6 6  11 93 ' ' * =2.39  calculations shall from the r e l a t i o n  f l o a t e d vs amount  be i l l u s t r a t e d ratio  of  of s u r f a c t a n t  3.6.  B.2.4.1  -  f  Calculations  The r e q u i r e d using  3.6  Floated  Added a t pH  Sum of Degrees o f Squares Freedom  vs  B4  of Variance f o r % S o l i d s of  Source of Variation  Added a t pH  Floated  Calculations Regression  Concerned with  Equation  the  by  solids added a t  Table Calculations  Amount o f Surfactant Added i n ppm X  Concerned with  B5 the Regression  Equation  Days A f t e r Samp!i ng  Solids floated Surfactant floated  y  xy  X  2  y  2  X  y  y  y  -  y  (e)  100  1.47  147.  10,000  2.16  1 .56  -0.09  7  100  1 .67  167.  10,000  2.79  1 .56  0.11  5  100  1 .72  172.  10,000  2.96  1 .56  0.16  15  150  0.87  130.5  22,500  0.76  1 .21  -0.34  3  150  1 .34  201 .  22,500  1 .80  1 .21  0.13  4  200  0.97  194.  40,000  0.94  0.86  0.11  12  200  0.80  160.  40,000  0.64  0.86  -0.06  E1000  28.84  E l 171 .5  E l 55,000  1 2.05  142.9  1 .26  E0.02  19 •  118 1171.5 - I 0 0 0 _ | _ _ 8 ^ i b  =  l  1 55,000 -  n w s w ~ u  u  "  u  " ° -  =  0  7  (  1 .26 - (-0.007 x 142.9) = 2.26  y = 2.26 - 0.007x  SS  SS  TOTAL  (8.84) 7  1 2.05  1171.5 REGRESS I ON  SS  RESIDUAL  155,000  =  °'  8  9  2  )  ;  (3)  (1 )  = 0.89  (6)  1000 x 8.84  TToobT  = 0.69  r  (7)  7  " °'  6  9  = °-  2 0  (8)  119  (9)  s =  O!89  R 2  0.2  "  7 7  -  (11)  5 3  (10)  B.2.4.2  Calculations " l a c k of  fit"  Concerned w i t h Test  the  T a b l e B6 Calculations  Amount o f Surfactant Added i n ppm  Solids floated Surfactant floated  y  Concerned with  2  y  the "lack  Number o f R e p e t i t i ons  <V  X  y  100  1 .47  2.16  100  1.67  2.79  100  1.72  2.96  24.86  27.91  150  0.87  0.76  150  1 .34  1 .80  22.21  22.56  200  0.97  0.94  200  0.80  0.64  El.77  21 .58  of f i t "  Degrees o f Freedom <n  Test  _2  y  n  2 R  y  2 y  i  "  H  - 1)  R  1 .62  3  2  2.62  7.87  0.04  1 .10  2  1  1 .22  2.44  0.12  0 .885  2  1  0.783  1 .566  0.014  24  20.17  _2 y  degree o f freedom  S S  PURE  SS  S  e  n  ERROR  LACK  2  =  =  . +  PURE  n A  computed  tabulated  B.2.4.3  *  ERROR  S S  f =  Z  A  "  ^  = SS ^RESIDUAL  OF F I T  S S  l  f o r pure e r r o r s - n - k  "  0  '  1  n  S S  ERROR  =  0 20 - 0  U  * ^  U  . 0.0425 n A O t  PURE  s * ( k - 2) e  F ( 1 , 4, .99) = 2 1 . 2 0  Plot of Residuals  3 = 4  7  - SS °°PURE  0.17 = - ^ =  RESIDUAL  =  = 7-  ERROR  _  0.03  0.0425(3-2)  1 22  figure B1. RESIDUALS OF THE REGRESSION MODEL OBTAINED FOR THE % OF SURFACTANT FLOATED •  I  o  2 -  u  0  -  CO  3  o  II  o  1  1  o  o  1  1  15 10 days after sampling  2 r  A  A  8  £  20  W  0)  I  >  5  u • •  III  I  •  50 100 p p m of s u r f a c t a n t  2 r  -5  8$  150 added  200  •  6  85 95 100 90 a c t u a l p e r c e n t a g e of s u r f a c t a n t floated  123  figure  B2.  RESIDUALS OF THE REGRESSION M O D E L OBTAINED FOR THE RATIO OF SOLIDS F L O A T E D TO S U R F A C T ANT FLOATED 0.2  I  o  0  0.2 h I  0.4  (0  3  0.2  "3  0  0)  II  I  i  i  5 10 15 days after sampling  20  r  0.2 h 0.4  u ••• III  50 100 p p m of s u r f a c t a n t  0.2 r  • •  150 added  200  cP  • •  -0.2 -0.4  0  0.5 1.0 1.5 2.0 a c t u a l r a t i o of s o l i d s f l o a t e d to surfactant floated  124  B.3  Cone!u s i o n s B.3.1  i)  ii)  iii)  iv)  v)  vi)  vii)  % S u r f a c t a n t F l o a t e d vs Amount o f S u r f a c t a n t Added  The p r e d i c t i v e model  i s y = 100.247  78% o f t h e v a r i a t i o n i n t h e data by t h e r e g r e s s i o n e q u a t i o n  - 0.099x  i s explained  The h y p o t h e s i s t h a t a l i n e a r r e g r e s s i o n does n o t e x i s t c a n be r e j e c t e d r u n n i n g a r i s k o f l e s s t h a n 1% o f b e i n g wrong  The^band around t h e r e g r e s s i o n s u r f a c e computed as y j ± 2.59 a p p r o x i m a t e l y i n c l u d e s 6 8 % o f t h e o b s e r v a t i o n s used t o e s t i m a t e t h e r e g r e s s i o n c o e f f i ci ents  A c c o r d i n g t o t h e l a c k o f f i t t e s t t h e model i s a p l a u s i b l e one w h i c h has n o t been f o u n d i n a d e q u a t e by t h e d a t a  The mean o f t h e e r r o r s i s z e r o  The p l o t s o f r e s i d u a l s r e v e a l n e i t h e r a t i m e d e p e n d e n c e n o r any v i o l a t i o n s o f t h e assumpt i o n s made, n e v e r t h e l e s s t h e y v a l u e s a r e s l i g h t l y u n d e r p r e d i c t e d . by t h e model (y < y )  125  B.3.2  R a t i o o f S o l i d s F l o a t e d / S u r f a c t a n t F l o a t e d vs Amount o f S u r f a c t a n t  i)  ii)  iii)  iv)  v)  vi)  vii)  The p r e d i c t i v e model  Added  i s y = 2.26 - 0.007x  77% o f t h e v a r i a t i o n i n t h e data by t h e r e g r e s s i o n e q u a t i o n  i s explained  The h y p o t h e s i s t h a t a l i n e a r r e g r e s s i o n does n o t e x i s t c a n be r e j e c t e d r u n n i n g a r i s k o f l e s s t h a n 1% o f b e i n g wrong.  The^band a r o u n d t h e r e g r e s s i o n s u r f a c e computed as y-j ± 0.2 a p p r o x i m a t e l y i n c l u d e s 6 3 % o f t h e o b s e r v a t i o n s used t o e s t i m a t e t h e r e g r e s s i o n coefficients  A c c o r d i n g t o t h e l a c k o f f i t t e s t t h e model i s a p l a u s i b l e one w h i c h has n o t been f o u n d i n a d e q u a t e by t h e d a t a  The mean o f t h e e r r o r s i s z e r o  The p l o t o f r e s i d u a l s r e v e a l e d n e i t h e r a t i m e d e p e n d e n c e n o r any v i o l a t i o n s o f t h e assumpt i o n s made  126  B.3.3  i)  % Solids  Floated  v e r s u s amount o f s u r f a c t a n t  The h y p o t h e s i s t h a t a l i n e a r r e g r e s s i o n does n o t e x i s t c a n n o t be r e j e c t e d , t h e r e f o r e i t i s n o t a d v i s a b l e t o assume a l i n e a r a s s o c i a t i o n between t h e d e p e n d e n t and i n d e p e n d e n t v a r i a b l e s  added  APPENDIX C  ANALYTICAL TECHNIQUES AND  C.1  Color  Determination As  was  CLEANING PROCEDURE  mentioned, Herschmi11er's modified  used w i t h o u t  m o d i f i c a t i o n ; so  i t will  not  colour test  be  (4)  reported  here.  C.2  Residual  Surfactant  A fairly v e y e d on the  Determination  e x t e n s i v e amount o f l i t e r a t u r e  the d i f f e r e n t  techniques  c o n c e n t r a t i o n of c a t i o n i c  proposed f o r  Van  Steveninck  therefore using  i t was  the m i l l An  diluted 10%  and  Mass a p p e a r e d  tried  effluent  on  determining  The t o be  method  suggested  t h e most  and  modified  two  remaining  effluent  drops of c o n c e n t r a t e d  1 27  runs  accordingly.  T h e n , i n s u c c e s s i o n , were added  sodium c a r b o n a t e ,  promising;  several tentative f l o t a t i o n  a d e q u a t e volume o f t h e  t o 50 m l .  sur-  s u r f a c e - a c t i v e agents i n  aqueous s o l u t i o n s ( 6 9 , 7 0 , 7 1 , 7 2 , 7 3 ) . by  was  5 ml  sodium  was of  1 28  hydroxide in  (prepared  50 ml  of d i s t i l l e d  prepared  daily  NaOH) and grade).  The  40 mg  was  cc t e f l o n  o f bromophenol o f dye  separatory Since  over,  a t 600  my.  For the  used as a b l a n k  was  taken  faction  and  effluent.  to  d e n s i t y of were  time  was  water  was  s o l v e n t and same  special  timed  % of  B e e r ' s law  surbecame  ppm. was  e s t a b l i s h e d by  runs, with d i s t i l l e d  Total solids  water i n s t e a d  were d e t e r m i n e d  before  h e n c e , t h e amount o f s u r f a c t a n t  technique.  w i t h i n a 3.  previously  known' c o n c e n t r a t i o n s o f  of the t e c h n i q u e  and,  graph,  d e v i a t i o n from  c o u l d be e s t i m a t e d  colorimetric  agreed  The  accuracy  after flotation  floated the  by means o f a c a l i b r a t i o n  the e x p e r i m e n t a l  of the m i l l  o f 0.001N  allowed  distilled  extraction  a t c o n c e n t r a t i o n s above 1.7 The  (freshly  c o n c e n t r a t i o n of the c a t i o n i c s u r f a c t a n t  (Figure C l ) .  repeating  ml  the s e t t l i n g  to submit a l l samples to the  from s o l u t i o n s w i t h  apparent  and  the o p t i c a l  same r e a s o n ,  i n s t e a d of the  The  determined  prepared  blue  phase c h a n g e d w i t h t i m e , a l l t h e r e a d i n g s  e x a c t l y a t 50-55 s e c o n d s a f t e r  procedure.  i n 100  hydroxide  (spectrophotometric  funnel  taken  c a r e was  sodium  hand-shaken f o r t h r e e minutes i n a  f o r 20 e x t r a m i n u t e s .  the o r g a n i c  g of C P .  of 1,2-dichioroethane  mixture  125  50  w a t e r ) , 1 ml  by d i s s o l v i n g  10 ml  stoppered settle  by d i s s o l v i n g  and On  compared w i t h the  difference.  the r e s u l t s  average both  methods  of  129  figure C1„  CALIBRATION G R A P H FOR VARIOUS CONCENTRATIONS OF SURFACTANT  130  C. 3  Floatable  S o 1 i d s D e t e rm i n a t i on  The f i r s t a n a l y t i c a l method ( 4 ) a p p l i e d termining had  t h e amount o f f l o a t a b l e  the following i)  ii)  iii)  questionable  solids  f o r de-  i n the m i l l  assumptions:  A l l the s u r f a c t a n t present i n the s o l u t i o n was f l o a t e d o r removed by f i 1 t r a t i on A s t r i c t l y s t o i c h i o m e t r i c r e a c t i o n took p l a c e between t h e s u r f a c t a n t and t h e p o t e n t i a l l y f l o a t a b l e s o l i d s present in the e f f l u e n t The f i l t r a t i o n s t a g e d i d n o t e x e r t any i n f l u e n c e upon t h e amount o f potentially flotable solids s t i l l present i n the e f f l u e n t a t that moment  In o r d e r t o d e v e l o p  a second  approach,  i t was n e c e s s a r y  d e t e r m i ne:  Then:  effluent,  a)  t o t a l amount o f s o l i d s p r e s e n t i n t h e i n i t i a l s o l u t i o n a f t e r i t s pH a d j u s t ment and b e f o r e t h e a d d i t i o n o f t h e surfactant  b)  t o t a l amount o f s o l i d s p r e s e n t i n t h e remaining e f f l u e n t a f t e r the experiment was c o m p l e t e d  a)  r e s i d u a l amount o f s u r f a c t a n t present in the remaining e f f l u e n t a f t e r the e x p e r i m e n t was c o m p l e t e d  to  131  1.  a + amount o f s u r f a c t a n t added b = d, t o t a l amount o f s o l i d s f l o a t e d  2.  amount o f s u r f a c t a n t amount o f s u r f a c t a n t  3.  d - e = amount o f s o l i d s f l o a t e d f r o m t h e e f f l u e n t , a t a f i x e d pH and w i t h a c e r t a i n i n i t i a l amount o f s u r f a c t a n t  No f i l t r a t i o n  s t a g e was  required.  The s o l i d s a n a l y s e s standard  to cool  that  i n t h e oven  purpose a M e t t l e r  H10T  period  decomposition  C.4  Cleaning  the  tap  0.1 mg.  No  The  Possible  ammonium s u r f a c t a n t for.  hours;  and w e i g h e d .  b a l a n c e was u s e d .  was a l s o t e s t e d  during  observable  Procedure each e x p e r i m e n t t h e f l o t a t i o n  scoured with  Finally  equipment  a b r u s h and r e c o v e r e d m e t h a n o l .  p r o c e d u r e was r e p e a t e d  solution.  were  occurred.  After thorougly  a t 103°C, f o r 12  to the nearest  decomposition of the quaternary heating  (74). Tests  f o r two h o u r s i n a d e s i c c a t o r  w e i g h t s were a c c u r a t e  the  to the  100 c c a l i q u o t s o f s o l u t i o n and r u n i n d u p l i c a t e .  The s a m p l e s were l e f t  For  w e r e done a c c o r d i n g  t e s t f o r " R e s i d u e on E v a p o r a t i o n "  performed with  allowed  added - c = e , actually floated  but t h i s  t h e e q u i p m e n t was  w a t e r and s e c o n d l y w i t h  fresh  time with rinsed  methanol.  was Next  a soap-water  twice,  one  with  132  Pipets, evaporating glassware  were soaked  solution, followed water.  dishes  and o t h e r  laboratory  i n a warm c h r o m i c a c i d - s u l f u r i c  by r i n s i n g w i t h  The e v a p o r a t i n g  dishes  acid  l a r g e volumes o f t a p  were a d d i t i o n a l l y  t h e o v e n , a t 103°C f o r two h o u r s , t h e n a l l o w e d  placed i n  to cool i n  a dessicator. The d i f f u s e r was c l e a n e d and  a mild  with  detergent  distilled  suction with  water.  This  using  avoid  hot  frit  any new f r i t t e d  treatment  removed l o o s e  concentrated  until  brush  i t was r i n s e d  filter,  particles  L a t e r , the general  permanent s t a i n  nitrite.  Afterwards  tooth  i t was washed  h o t h y d r o c h l o r i c a c i d and r i n s e d w i t h  m a t t e r s u c h as d u s t . to  a soft  w a t e r and b a c k w a s h e d w i t h f r e s h m e t h a n o l .  Before by  solution.  with  sulfuric  of the f r i t acid plus  Then h o t d i s t i l l e d  distilled  of foreign  procedure  was t o c l e a n  followed i t with  a few d r o p s o f sodium  w a t e r was p a s s e d t h r o u g h t h e  t h e pH o f t h e wash w a s t e r r e m a i n e d n e u t r a l .  APPENDIX D Flotation  of Kraft M i l l  Effluent.  Tabulated  First  pH  Initial Amount o f Days Temp. % S u r f . C o l o r Surfactant After °C F l o a t e d (Pt-Co A d d e d , ppm S a m p l i ng Units)  Fi nal Color (Pt-Co Units)  Batch  Results  Set  % Initial Color S o l i d s , ppm Removed  Sol i d s % F l o a t e d , Sol i d s Fl o a t e d ppm  Solids Surf,  NA  NA  NA  NA  NA  NA  NA  NA  NA  NA  98.7  NA  NA  NA  NA  120  88.8  NA  NA  NA  NA  1040  NA  NA  NA  NA  NA  NA  1213  370  69.5  NA  NA  NA  NA  1100  220  80  NA  NA  NA  NA  920  225  75.5  728  13  1 .78  .53  5.6  200  5  35  60.5  1320  400  69.7  NA  4.6  200  6  35  78  1330  30  97.7  NA  5.6  150  7  35  43  1340  180  86.6  4.6  200  9  32  80  1175  15  4.6  100  10  26  51  1075  5.6  150  11  28  25.3  6.6  150  12  28  6.6  200  13  28  13  5.6  100  14  25  24.5  6.66  Experimental  '  floated floated  CO  co  Second S e t Initial Amount o f Days Temp. % S u r f . C o l o r pH S u r f a c t a n t After °C F l o a t e d (Pt-Co A d d e d , ppm Sampl1ng Units)  Fi nal Color (Pt-Co Units)  % I n i t i a l Sol i d s % Color Sol i d s , F l o a t e d , Sol i d s Removed ppm ppm Fl o a t e d  Solids Surf,  floated floated  960  140  85.4  846  176  20.80  1 .34  90.4  1250  140  88  732  150  20.5  1 .67  29  24.7  1460  225  84.6  848  7  28  67.7  1360  115  91 .5  881  100  8  25  27  1410  285  79.8  860  3.6  200  12  25  81 .25  940  35  96.4  784  158  20.1  0.97  4.6  150  13  29  70.7  1050  105  90  771  133  17.25  1 .25  5.6  200  14  35  10  1260  105  91 .7  819  36  3.6  100  15  25  92.1  850  120  86  747  160  21 .3  1 .72  4.6  200  16  25  75  1070  40  96.4  735  134  18.23  0.94  4.6  100  17  26  30  1050  220  79  703  24  3.6  200  19  28  81  870  35  96  680  130  3.6  150  4  30  87.3  3.6  100  5  25  5.6  150  6  4.6  150  5.6  6 138 5  0.71 15.7 0.58  4.39  3.41 19.11  0.16 1 .36 0.18  1 .80  0.80 0.80  co  Third  pH  Days Amount of After Surfactant Added, ppm S a m p l i n g  Temp. °C  % Surf. Floated  Initial Color (Pt-Co Urn* t s )  Set  Final  %  Col or (Pt-Co Units)  Color Removed  Initial Soli ds, ppm  S o l i ds Floated, ppm  %  Sol i d s Floated  820  NA  NA  647  0  .66  820  NA  ' NA  647  5.3  25  940  NA  NA  508  89  25  80.3  680  25  96.4  485  105  5  25  17  765  105  86.3  525  21  4  200  6  25  51  785  15  98.2  499  66  13.23  3.6  100  7  25  90  71 5  40  94.5  544  132  5.6  200  25  32  880  50  94.3  497  56  too  1  25  5.6  150  1  25  6  5.6  200  2  25  3.6  150  3  4.6  100  4.6  20  Fourth  8  25  26  NA  NA  NA  3.6*  100  9  27  50  NA  NA  NA  '(sample  not  diluted)  ,  17.52  1.78 .87  .65 1  ..24 .64  24.26  1.47  11  0.88  .27  Set  50  3.6  .53  .82  21  floated floated  NA  0  0  5.6  Solids Surf,  681 1  558  0  0  •1 26  8.08  o 2.52  APPENDIX E  BIBLIOGRAPHIC SURVEY ON PROPOSED METHODS FOR REMOVING COLOR FROM KRAFT MILL EFFLUENTS .\tocoio, W . A - Color removal from kraft mill effluents. Proc. • 0.C jnd Waste Conf., Purdue Univ. Eng. Bull., Extension Scr. nc'S7:465-76 (1955). r i problem of color removal from kraft mill effluents has not kept pace ."•'li the progress made in the biological stabilization of these effluents, prin•'<IWbecause the color-imparting substances exert little or no biological I!;cii demand; hence the soiuticn of biological stabilization was considered — <rc pressing. However, color removal is important, because the- presence of "\;r is evidence to the public that the stream contains such, cftlucnts and, ...,agh it does not create stream pollution, may lead to unwarranted an.l • -••jst accusations. Tl:e color bodies in kraft effluents are primarily iiguin :'i:pounds whose color increases with increasing p H values; at p l l values o:» • t aciii side, they become increasingly insoluble. The removal can he accorn•:-!;cJ by either biological, physical, or chemical means; the use of hydratcd x offered the greatest promise of eventual success from economic and .coition standpoints (.cf. B.l.P.C. 23: 5S3-4). In all-previous attempts for ;• !-jr removal from kraft-mill effluents, the matter of sludge handling has !..<-n the uiisumiotmtable obstacle; hence, hydrated-limc sludge conditioning "vilsorls received first consideration. Two multistage methods were developed; V'.li involve the carbonation of the sludge, and one involves further treatment the carbonated calcium-organic sludge with black liquor, with the result th.it economical dewaterir.g in standard equipment and recovery of the calcium content of the sludge in re-usable form become possible. Details of the two procedures a:e given. The development of a satisfactory sludge-handling method does not signify that the complete solution to the color proi/icm hi'.s ttcn found; other factors still require extensive investigation. 3 tables, 4 figures, and 3 references. E.S. c  2 4 3 0 . Colour and methods for colour removal. N E M E R O W , N . L . Proc. II th Industr. Waste Conf., Purdue Univ. Engng Exin Scr. No. 91. 1956. 584-594. The removal of colour from waste waters is important from an aesthetic point of view, and the author discusses various aspects of the removal of colour.' Methods for measuring the intensity of colour are indicated briefly, and the concent of reflected light from a river water and the need for an instrument to measure it. arc discussed. The cxocriencv.s of various investigators in the removal of colour from waste w.-.tcrs are reviewed. These show that colour can be removed by many methods, with '.arious degrees of efficiency. The chemical and physical structural characteristics of coloured compounds which effect colour removal are shown in a table. A bibliography of 29 references is appended.  136  Y/IN'CET, RUSSELL L . The pulp and paper industry- pollution abatement program in the United States. Pulp Paper Mag. Can. 57, no. 3: 224-6, 230 (Convention issue, 1956).  The function, research activities, problems, ar.cl achievements of the N'a-l tional Council for Stream Improvement are described. Major problems center around solids removal, sludge dewatcring and disposal, C.O.D. reduction,i toxicity, and color removal. Over the past decade, U . S. pulp and paper in-' ciustry pollution/ton of product has been decreased by over 50%. C.L.B.  372.  NKMEROW, NELSON L . Color and methods for color removal. Proc. 11th Ind. Waste Conf., Purdue Univ. Eng. Bull., E x tension Ser. no. 91: 5S4-94 (June, 1957).  Because of complaints from the public, the removal of color from waste waters is often more important than the removal of B.O.D. For the measurement of color intensity and quality the s(>cctrophotometcr, the filterphotomcter, or a color comparator (such as the Hellige comparator) may he used. Both transmitted and reflected light may he measured in sewage and waste waters. The first is useful in determining the efficiency of color removal, whereas the second is measured because it is the light seen by an ohserver A review of the literature pertaining to methods used for the removal of color from waste waters is given. 1'ast experience indicates that color may he removed hy many methods with varied degrees of efficiency. The chemical structure of the colored com|>ouud< is an important factor ii* "'"c choice of. the method of removal, i tables and 20 references. J.S. ;  1034.  MCIXN-IS, J-  S..  MILLS,  K . II..  and  COLLINS, T . T . , JR.  Color and sulphide problems in water treatment at Hudson Pulp & Paper Corp. Paper Trade J . 142, no. 27: 32-5. 3 8 ; no. 29: 26-34 (July 7, 21, 195S). iJevelopmcnts of the water-treating facilities and procedures at ihc Htidsoil Pulp and l'apcr Corp. plant at Palatka. Fla. arc discussed. Practical aspects involved in the removal of color and sulfide from water for use in the manufacture of bleached pulp and in drinking-water systems arc described. Methods for the removal of organic colorants in water include coagulation, destruction by chlorination and other oxidizing agents, decoloration by adsorption on charcoal and other surface-active materials, filtration, and electrolysis. The most practical of these procedures is coagulation of the negatively charged color bodies with sufficient alum at optimum pH using clay as a weighting agent and a proper coagulant aid. Recent years have seen the development of several excellent coagulant aids which help materially in the reduction of color by broadening the pH range at which tloc formation occurs and improving the settling and filtering characteristic of the color floes formed. The effectiveness of some of these materials (activated silica and Separan) has been shown by mill 'lata. Pilot-plant studies on sulfide removal indicated the important role of sulfur bacteria, in conjunction with aeration, for the removal of sulfide atal reduction of chlorine demand. These considerations are important where the water is to undergo a subse«|ucnt softening operation followed by chlorination before use in the mill process. The second section of the article includes a detailed literature summary on the subjects of color and sulfide removal in water treatment. 2 tables. 1 figure, and 103 references. • R.A.S.  EK.KCKR, HF.KBK.RT F., a n d BROWN", R I C H A R D 1. 'Hie s u r f a c e reaction method f o r c o l o r removal from kraft blcachery effluents. T a p p i 4 2 , n o . 3 : 2 - 1 5 - S ( M a r c h , 1 9 5 9 ) . Previews research by tlie National Council tor Stream Improvement anil by several kraft mills lias shown that color can he removed successfully front combined kraft and bleach cfilncnts by precipitation with lime. The resulting sludge, however, has been extremely difficult to dewater to a dryness suitable for rcburning in the kiln. The authors describe laboratory and bench-scale pilot plant experiment-; in which caustic extract from a bleached kraft mill is treatnl by application to a prccoat of hydratcd lime on a rotary vacuum filter. The limc-liguin reaction takes place at the surface of the prccoat, forming a film which iv.ay be continually doctored oft exposing a fresh reactive surface. The ltmc-nrganic film is dry enouch to be fed IQ the kiln along with lime mtvl and culor removal is in excess of 95%. A larger scale pilot plant 6781.  lias hcni set up at a southern bleached kraft mill by an equipment m a i m - \ faclurcr. and the process• »••» now under evaluation.-(> figure*. — K.A.S.  1232. New approaches lo pulp and paper mill waste Ircalnicnl. C l l l M . IF. \V. ftufuUr." Wastes, 1959,4, 2UO-204. The author reports on and discusses rescue!) and clcwlopncnt work in progress to improve the treatment of pulp •uul paper mill ctllucnls. The three baste problems bciny studied arc the ilcwatcrinp ami disposal of sludges obtained from sedimentation processes, reduction of colour in bleaching waste waters, and reduction of R.O.O. Developments in the methods employed for dewatering sludge arc outlined (sec Wat. Pollut. Abstr., 1959. 32. Abstr. No. 2103). Studies show thai addition of fly ash to the influent of the sedimentation tank improves sedimentation and increases the rate of dewatering of the sludge; the possibility of applying fly J;h as a preliminary coating on tillers is being investigated arid preliminary tests have given good results. Preliminary pilot tests on an aerobic thermophilic process for •the digestion of sludge indicate that substantial quantities of volatile matter can be destroyed in a relatively short time by this method. l:\pIoration of all suggested methods for reducing colour has revealed that the most promising is the lime treatment technique; it was recently discovered that caustic extract from kraft bleaching could be almost completely decolorized by vacuum filtration through a bed of hydratcd lintc. Previous work carried out to increase the efficiency of B . O . D . removal from tne waste waters produced by the paper industry is reviewed. It has been found that aeration and recirculation in stabilization tanks greatly improves oxygen transfer, hence increasing the degree of oxidation occurring per unit of storage time. Graphs i't included to illustrate the results obtained.  1149  BfjJCFs Herbert F . Chemical treatment and water reclamation. P u l p Paper M a c . Can. 65, no. 6: T260 2 (June, 1961). A chem. process tor the redn. of both color and B . O . D . from kraft pulping and bleaching diluents has been devd. It involves slaking lime from the kiln with part of the diluent to be trd. and adding it to the remaining c-filncnt. O r g . cpds., inch color bodies, are adsorbed on the lime, which is then sepd. from the effluent in a thickener anddewatcred on a vacuum filt-r or centrifuge. T h e supernatant from the thickener, together with the filtrate from the vacuum filter, is then carbonated with lime-kiln gas at controlled p H in a reactor to reclaim lime in soln. and further decolorize the diluent. •CaCGY from the reactor is "reclaimed on the mud filter in the causticizing svstcm. Tt'.c filter cake from the lime trmt. contains the added lime still as C a ( O I I ) : ™d is used tocausticizc the green liquor. T h e liquor dissolves the org. cpds. from the lime and they appear in the white liquor produced. After the digester, they end up in the black liquor sent to the recovery furnace, :  where they are burned together with org. matter dissolved out of the d i gested wood. This process gave a better than 909c color removal a:.d a B . O . D . redn. of 40-6070. W i t h some modifications (elimination of the first elarifier), it was found applicable to the trmt. of X S S C diluent as well, though at added expense (need for a lime kiln and slaker). The residual color (300-SGO units) of the linie-trd. cftlucnt is gen. acceptable for discharge into streams, but is loo high for water re-use in some processes. T w o methods for addnl. color removal were investigated, one based on activated carbon and the other on foam fractionation. The latter required use of an external surfactant to produce a suitable foam and gave uneconomical enrichment ratios for color removal, but might he suitable for B . O . D . redn. and addnl. tall oil recovery from diluents rich in tall oil soaps. The activaicd-C process, at decreased p H and elevated temp., gave nearly total color removal from efi'.uctiis of ail kraft bleach plant stages, but the economics of the trmt. require further large-scale study and improvement. Total cost of h.ig'adegree kraft diluent trmts. for nearly closed water recirculation liucl. hiol. trmt., lime decolorization, C adsorption, and desalination hy clectroilialvsi-) is still too high, viz., 50 cents per 1000 gal. S ref. C.hiB.  5649. '.  M C K I ' H Y , Xelson F . , antl GISECOKY, Dale R. Removal o f color f r o m iulfatc pulp w a d i liquors. Proc. 19th Ind. Waste Conf. i h r g . B u l l . Purdue Univ. 4'.'. no. 1; Eng. Kxtensicm Ser. no. 117;; 59-7!> ( M a y , 195-1 ; p u b l . J a n , 1965).  Studies concerning the effectiveness of a high-pressure (600 to 3200 p.si.g.)/l::gh-ten:p. (254 to 4 C 0 C . ) trmt. (using a P a r r Pressure Reaction A p p . ) in the removal of color from the diluent resulting from the caustic extn. stage of a kraft'pulp blenching process show that under basic conditions ( p l l 7.5 or 9.3), essentially complete diluent vaporization is necessary for effective decolorization to occur. However, under acidic conditions ( p H 3.5 or 5.5), effluent light transmittancc of up to 50% (compared to distilled water) was attained with effluent vaporization of only 357?- A transmittance of up to 937i< was attained at 100;o diluent vaporization. The mechanisms of the decolorization reactions are unknown. Holding time under steadystate conditions had only a small' effect on decolorization. Tests indicate that the sludge obtained as a result of decolorization can be removed by filtration. About 3,COO ga!. of dark-colored waste arc produced/t._of_ pulp bleached. 10 ref. L.G.S.  //S54.  Davis. C. I... Jr. T E R T I A R Y T R E A T M E N T 01 K R A F T M I L L E F F L U E N T INCLUDING CHEMICAL C O A G U L A T I O N FOR COLOR REMOVAL. Tappi 5 2, no. 11: 2132-4 (Nov.. 1969).  To protect estuary waters, the Ga. State Water Quality Control Board required clarification, chem. trim., and biochem. stabilization ol krat't linerbourad mill waste prior to discharge. The decree of chem. trim, is defined in terms of A PI color units and is lumteJ to 30 ppm with a m a \ . waste discharge of 10 million gal., Jay. The 5-day BOD is limited to S00 lb. day, and suspended solids are limited to ID ppm. A tnnt. system to meet these specs, was put into operation in March, I96ts at the Rieeboro. Ga. mill of Interstate Paper Corp. In sequence, it involves waste tlocculation with lime i 37 L/day caled. as 90 c CaO). removal of lime sludge and settleaMe solids, natural stabilization in an oxidn. basin satd. with Ca hydroxide at pll ca. 12.0. mech. aeration, and controlled discharge. The mill's rated capacity is 400 t./day of unbleached kraft Iincrboard. Process water requirements texcl. cooling) are I 2.500 {al./t. only about half the ind. av. A prelim, rept. cf operating experience and costs is given. Total capital investment for waste Umt. is cstd. at $2,500,000 U0"c of mill cost), of which nvarly $500,000 went into the color-removal system. Total first-year cost for operation and admin, of the system (incl. 5269,000 tor chemicals) was SbS3,700. or S3.19 per t. of prodn. (assuming 10-yr. linear depreciation). The color-removal installation was supported partly by a $467,000 grant from the Fed. Water Pollution Control Admin. CUB. :  SS53,  Marton, J . ; Stern, A . M . ; Marton, T . D E C O L O R I Z A T I O N O F K R A F T 13LACK LIQUOR WITH POL YPOR US VERSICOLOR, A W H I T E - R O T F U N G U S . Tappi 52, no. 10:1975-81 (Oct., 1969).  A strain of the white rot fungus, Polypoms versicolor, which had  been previously adapted to kraft lignin. significantly reduced the color of dild. pine kraft black liquor. The mechanism of the color removal was studied by using 3 kinds of lignin (spruce MWL, pine Indulin A T , and pine black liquor) and several lignin model substances. Lignin was not sufficient as the sole carbon source to support cell propagation: cell growth required an easily metabolizable sugar and other nutrient suppls. The intensity of cell growth and, simult., the degree of dccolorization were higher under aerobic than under anaerobic conditions. The acrobically grown ceils adsorbed lignin on their surfaces: hence phys. adsorption plays a major role in removing color, rendering the process less attractive from a technol. point of view. Part of the lignin was metabolized and chem. degraded. Under anaerobic conditions, where the rate of dccolorization was much lower, phys. adsorption also became less significant. Adsorption did not play an important role for the phenolic lignin models; most of them could be metabolized caiily. The reaction prods, were studied by means ol" differential spec:ry. .and thin-layer ch.oniat. The main steps involved in the aerobic U T U . arc of an oxidative nature, in line with a phenol oxidase mechanism advanced recently by Kirk, Harkin, £ Cowling. The formation of quinoid intermediates was demonstrated. The reactions of the phenolic models and their potential relations to the behavior of lignin chromophores are discussed. 16 ref. C.L.B..  10561.  Luncr. P.: Deuce. C\: P.enneit. D.: Kune. F.-L. MECHANISMS OF C O L O R R E M O V A L IN T i l l : T R E A T MENT OF PULPING A N D B L E A C H I N G E l 1 LIT N IS WITH LIME. I. T R E A T M E N T 01 C A U S r i C E X T R A C T I O N STAGE. B L E A C H I N G E F F L U E N T . NCASI Tech. Hull. no. 239: 52 p. (July, 1970).  Commercial spent liquor from the N.iOII estn. stage ni'.a softwood kraft bleaching sequence was sepd. into precipitahlc and nonprecipitable fractions by trim, with lime (CaO) or slaked lime (C"J hydroxide). The solid; comprising each fraction were suhjcvVd '.•> elemental and function.;! group anal, and mol.wl. detns. as a me:::!* of clarifying the mechanism of the lime pptn. process 'or color removal. Results showed that removal of color from the spent NaOII e \ l n . liquor with lime is a chemical rather than u phy». process and that it is dep. on the presence of ciiolie and phenolic O i l groups and on the mol.wt. of the solids contained in the liquor. Enolic and phenolic OH groups on structures contg. chromophoric pjoups react with lime and other Ca cpds. under alk. conditions forming insol. Ca salts which ppl. In spent NaOH oxtn. liquors the phenolic O i l content is low, and pptn. results primarily from interaction of lime with enolic O i l groups. The mol.wt. of the solids is a determinant factor in the lime pptn. process as it affects the soly. of the resulting Ca salts. 32 ref. WAV. 10562.  Luncr, P.: Donee. C : Bennett. D . : O t a . M . M E C H A N I S M S O F C O L O R R E M O V A L IN TIIF. T R E A T M E N T OF' PULPING A N D B L E A C H I N G E F F L U E N T S WITH L I M E . II. T R E A T M E N T O F C l l l . O R I N A T I O N S T A G E Ii L E A C H I N G E F F L U E N T S . NCASI Tech. Bull. no. 242: 24 p. (Dec., 1970);cf. A B I F C 41: abstr. 10561.  As in the case of the previous work on NaOH extm stage bleaching effluent, these studies demonstrated that removal of colored erg. matter from spent chlorination stage blenching cftlucnt by lime involved Ca salt pptn. which was dep. on (1) the presence of weakly acidic cnoiic and, lo a lesser degree, phenolic O H groups, and (2) on the mol.wt. of the dissolved solids present as a determinant of soly. of the resultant Ca salts. It is possible as well, that during lime neuln. of chlorination stage effluent, hydrolysis of chloro substituents causes further formation of weakly acidic O i l groups which react with lime forming insol. Ca salts. 18 ref. W.W.  9227.  Sameslmna, K . ; Kondo. T . S T U D Y ON T i l l : COLOR O F PULP INDUSTRY W \ S U LIQUORS. I. RELATIONSHIP BETWEEN I HE ( O l OR OF WASTE LIQUOR F R O M K R A F T PI LP ML LTTST U'.F BLEACHING A N D EIIE I S O L A T E D (IILOR1NFOXYLIGNTN. J. Japan Wood Res. Soc. iMoku/ai GakkaUhi) 16. no. 7: 347-52 (Nov.. 1970). [Jap.: Engl. sum.| ;  Pine and birch kraft pulps were subjected to multistage bleaching by the Cl:!!!:!) sequence, and the color-causing substance in the spent bleach liquors was isolated by acidification to pll 1.0 lid. by ccntrifugation and dialysis. This substance, tentatively called CToxyliguin, contributed ca. 80^ to the total color and ca. 45'. to the COD of the effluent. It contained only ca. 1.6"- carbohydrates las xylose), showed a shoulder on the U V absorption curve at ca. 2S5 nm., and gave an IR spectrum charac. of lignin. In comparison with other lignin prepns., it displayed marked light absorption in the visible spectrum but no charac. absorption max. Its mol.wt. was rel. high, comparable to that of pine dioxane 'Jgnin. The dark cotaf may derive largely from reactions assocd. with lignin rfcni.'ihylalion. in which the I'll and C O groups act as chromophores and the COOH f.roup as auxochromc. 18 re 1". • C.L.B. ;  1602.  Mohanrao. G. J.; Subrahmanyam, P. V. R. STREAM A N D A I R POLLUTION P R O B L E M S RELATED TO DISPOSAL or E F F L U E N T S F R O M PULP A N D PAPER  INDUSTRY. IpptaS, no. 3: 155-63 (July-Sept., 1971). [Engl.)  This is mainly a rev. regarding stream pollutants. The main water pollutants are high pll, H O D . C O D , suspended solids, and coloring matter. U O D and solids may be reduced to reasonable limits by means of activated sludge ttnu. and by anaerobic lagoons. The latter ire less expensive. Color and C O D are difficult to remove. Suspended solids that emanate mainly from machine waters can be reduced initially by ituraplant techniques involving savealls, and later by coagulation and sedimentation. Possibly it would be well to reduce B O D and to correct the pll of pulp mill effluents by means of anaerobic lagooning. flic anaerobic effluent can be subjected to Eand disposal or treated by aerated lasooning before discharging into a stream. Ail pollutants from kraft mills are also considered briefly. They consist mainly of hydrogen sulfide, methyl mcrcaptan, dimcthvl sulfide, and "particulate pollutants". Their sources are outlined. 30 ref. L.E.W.  1558.  Basu, S. STUDIES ON CARBONATION OF BLACK LIQUOR TOR LIGNIN PRECIPITATION AND ITS SUBSEQUENT SEPARATION. Ippta 8, no. 4: 207-14 (Oct./Dec., 1971). [Engl.]  A study was made concerning the feasibility of removing "lignooiganic" components from black liquor by "carbonation" in rendering the liquor suitable for causticization of Na cpds. to NaOH. The process parameters during carbonation included the degree of turbulence, temp., pressure, time, and final pH. All of these were studied, and the optimum conditions were detd. Pressure carbonation at 4.5 kg./sq.cm. fid. by trmt. with acetone to insure coacervation-flocculation had a pronounced effect on removal of the ligno-organic components, obtained as a lyophilic colloid. Carbonation at atm. pressure was carried out on a small scale. Pressure carbonation was done in an elec. heated 18-liter autoclave provided with arrangements for recirculating the liquor through a heat exchanger. The response of the black liquor to coagulationcoacervation flocculation as a means of lignin removal was found to be correlated with the props, of the original ccllulosic raw matl. with respect to lignin content and distribution. 21 ref. L.E.W.  10S67. Davis, C L . COLOR R E M O V A L FROM K R A F T PULPING E F F L U E N T HY LIME ADDITION. Water Poll. Control Res. S-'r. (EPA) no. 1204CEN<~ 12/71 : 72 p. (Dee. I, 1971). [Avail, from NTIS; PI121S306] cf. AB1PC 40: abstr. 6S54 and ABIPC 42: abstr. 2729.  1589.  Interstate Pancr Corp. COLOR R E M O V A L I-ROM K R A F T PULPING E F F L U E N T BY LIME ADDITION. Water Pol). Control Res. Scr. (U.S. EPA) 12040 ENC: 117 p. (Dec. 1, 1971). [Supt. Dee., GPO, Washington, D.C. 20402; S1.25]  A prototype color removal sv slim using slaked lime was designed, constructed, and operated as m integral part of a tertiary trmt. system tor total process effhunt from a kraft lincrboard mill (Interstate Paper Corp.) at Ricehnro, Ga. The lime pptn. process was combined witli primary clurificiiion (Id. by natural biochem. lake stabilization and meeh. aeration. Results showed that the system can operate under widely varying conditions to yield a rel. const, effluent color of ca. 125 ppm APHA color units by dosage of the original effluent (1200 ± 200 p.jm color units) with 1000 ± 5 0 ppm of Ca hydroxide. Assuming a price of S15.35/t. of 90Sc CaO lime, this trmt. level costs S53.73 per million gal. of effluent. Equipment evaln. indicated substantial savings in capital cost for future installations, since performance is directly related to control of lime feed. The Ca was recovered continuously under mill conditions, using a statist, designed prorram which is described. The total tertiary trmt. system achieved an overall 5-day BOD redn. of 98%; the final discharge averaged 6 ppm BOD. 19 ref. C.L.B.  569.  Dalpkc, H.-L. STUDIES D E A L I N G WITH E F F L U E N T T R E A T M E N T B Y THE USE O F A C T I V A T E D C A R B O N . Papier 26, no. 1: 4-10 (Jan., 1972). [Gcr.; Engl. & Fr. sum.)  The removal of biologically harmful substances (characd. by 5-day UOD dclns.) from mill effluents is known to be essential in preserving (or restoring) waterways. Besides biol. purification, a no. of chem. and phys. purification processes have been suggested for redg. 5-day BOD. One of these involves the adsorptive action of activated C. The author gives cxptl. data obtained in a scries of 4-slagc lab. cxpts. involving effluent trmt. in 4 C-contg. cylinders, and covers the thcotct. basis, for van dcr Waals adsorption. Apparently, the effluent studied could be decolorized completely at a specific flow rate of 1.5 liter/hr./kg. C. Such trmt. also removed the residual fibers completely, and lowered the 5-day BOD level to r.ot over 25 mg. O/litcr. The technique is shown in appropriate illustrations. 2 ref. • L.E.W.  '.855.  Subrahmanynm, P. V . R.; Sadian, P. C ; Mohanrao, G. J. ASPECTS 01 COLOR R E M O V A L I'ROM PULP A N D PAPER MILL I I I I . I T NTS.  Ippta y, no. 1: 20-3 (Jan./March, 1972). I Engl.) Lignin is described as an "aesthetic pollutant", and its "nonbiodcgradabilir." is discussed. I-'or the removal from effluents of color due to lignin, chemical methods like massive lime trmt., hiol. methods like activated sludge trmt. and the utilization of various fungi, and phys. methods like adsorption by activated carbon or soils have been suggested. Lab. studies by the present authors, using 8 different soils, are described in detail, it is .shown that color redn. is directly proportional to soil cation-exchange capacity. The requirement of land for trg. pulp-mili effluents is also caled., assuming a steady rate of percolation and a given rate of evapn. 12 ref. L.E.W.  4154.  Lcszezvnski. C . D E C O L O R I Z A T I O N Oi- K R A F T M I L L E F F L U E N T S . Przeglad Papier. 28, no. 3: 8S-9 (March, 1972). (Pot.J  Colored substances in the effluents from kraft mills, consisting mainly of lignin derivs. and tannins, are not degraded in the activated sludge purification process. Although these substances are not toxic to aquatic organisms in conens. presently found in waters, they are harmful by inhibiting the penetration of sunlight into the water, increase the costs o f trmt. of water, and prevent the use of the waters for recreational purposes. For these reasons, many methods have been proposed for decolorization of effluents prior to their disposal into natural waters, inch ppm. with metal salts, adsorption on activated C, reverse osmosis, etc. Among these methods only trmt. with lime was found suitable for ind. purposes The process, devd. and patented in the USA, consists essentially in mixing the effluents with lime, scpg. the ppt. contg. the colored substances by sedimentation, dewatering it to a dryness of 40-60C£, and using it in the causticization plant. The process has been introduced in three U.S. mills, notably the Riceboro (Ga.) mill of the Interstate Paper Corp.. the Georgia-Pacific Corp. mill in Woodland (Maine), and the Continental Can Co. mill in Hodge (La.). The decolorization procedures and their efficiency at the three mills are described. Also mentioned are pilot plant studies carried out by the International Paper Co. and the American Can C o . on lime decoloration of bleaching effluents, and on modifications of kraft pulp bleaching processes to reduce the load of colored substances in effluents. 13 tef. J.S,  'i';\S.  Dytncrskii, Y u . I.; Svittsov, A. A . ; Romanenko, Y u . K.; Zhilin, Yu. N.; Semenov, V . P.; Trupchaninova. O. V . USE O F R E V E R S E OSMOSIS A N D U L T R A F I L T R A T I O N FOR Till- PURIFICATION OF E F F L U E N T S . Bumazh. Prom. no. 7: 22-4 (July, 1972). [Russ.]  Purification of mill effluents by the methods of reverse osmosis and ultrafiltration was studied in the lab. of the Baikal .pulp mill. Some results are repotted of cxpts. carried out on efilueuts which have been purified chem. and Idol., on nonpuriiicd effluents, and on black liquor evapn. condensates. In both purification methods C A membranes of domestic prudn. were used. The results of these preliminary cxpts. indicate tlial purification is more effective compared to the presently used methods, and that the purified effluents can be used as recycle process water. The advantage of ultrafiltration over reverse osmosis is a high efficiency at rel. low pressures (3-10 kg./sq.cm.). On the other hand, reverse osmosis removes dissolved mineral cpds.; until now such removal has been the most complex problem in effluent purification. J.S.  453(U). Lavrinenko, I. K.; Soivanik, P. A . ; Vilenskii, V . I. PURIFICATION O F PAPFR M I L L E F F L U E N T S BY MICROITLTRATION. VodosnabzJi. Kanaliz. Cidrotckli. Sooruzh., Resp. Mezhved. Nauch.-Tekh. Sb. no. 15: 40-4 (1972). [Russ.] It was shown that it is possible to use microfiltcrs for the purification of paper mill effluents and of process water used by such mills. From: Ref. Zh., Kliim. no. 24: abstr. 1557 (Dec, 25, 1972). D.M.C  9719(R). Tyler, M . A . ; Fitzgerald, A . D. A REVIEW O F C O L O R R E D U C T I O N T E C H N O L O G Y IN PULP A N D PAPER MILL E F F L U E N T S . CPPA Tech. Sect. Proc. 1972: D l 16-23; discn.: D123-5. Over 60 lit. repts. on effluent trmts. for color removal were studied to assess the status of ind. practices. Lime trmt. is the most established method, achieving 65% color removal from bleached kraft effluent at a capital cost of S1-1-5 million and operating costs of S 1.0-1.5 per ton of pulp. Coagulation with alum gives similar results at similar costs, but requires improved systems for handling the difficultly dewatcring sludge. Adsorption on activated C accomplishes complete color removal, but at high operating costs. Switching from CI to oxygen bleaching of kraft pulp would reduce effluent color by 60-65% and save ca. 52 per ton of pulp in chem. consumption. Capital costs for such a conversion arc cstd. at S2 million. 8 ref. C.L.B.  3028(M). Gould. m. NEW LIME PROCESS EOR R E M O V A L O F C O L O R F R O M KRAFT MILL EFFLUENT AT GEORGIA-PACIFIC ICORP.'S) W O O D L A N D , M A I N E , M I L L . TAPPI Envir. Conf. 1972: 141-7. The paid, effluent-decoloring process described involves trmt. of alk. extn. waste from a kraft bleach plant with ca. 2000 ppm. of lime before entering a solids-contact clarificr. Reaction of lime with color bodies precipitates a scttlcablc sludge which is continuously removed from the clarificr. The lime sludge underflow is then mixed with prefiltcrcd lime mud and dewatered on a conventional belt filter. The dewatered sludge is fed directly into the lime kiln where (lie color bodies arc burnt off and the lime is recovered. The full-scale trmt. plant (installed after pilot-plant trials) removes ca. 907o of the color and ca. 45% of the BOD from the effluent of the alk. extn. stage, and recovers ca. 80% of the lime used. Mill experiences, inch process parameters, costs, and maintenance, after the 1st yr. of operation are indicated. C.L.B.  1613.  Oswalt, J. L . ; Land, J. G„ Jr.  f£r?£JVr  M0VAL ' L L EFFLUE N T S BY MASSIVE LIME T R E A T M E N T . Envir. Protection Techjiol. Ser. EPA-R2-73-086: 109 p (Feb., 1973). F  R  0  M  K  R  A  F  T  P  U  L  P  M  r  A demonstration plant was installed and operated to determine whether trmt. with 20,000 ppm lime could effectively and economically decolor kraft pulp mill effluents, notably the black effluent from the alk. extn. stage of the bleach plant, and the reddish-brown effluent from the final unbleached pulp washing stage. The impact of massive lime trmt. on a hypothetical 1000 t./'day bleached kraft integrated mill is described. Using all the lime normally available in such a mill would allow trmt. of 4 million of the 29 million gal. of toral effluent. This would remove 72% of the total effluent's color, reducing the residual color to ca. 740 API IA units at an cstd. cost of $1.80/t. ol" pulp, incl. depreciation, insurance, and taxes. 10 ref. C.L.B.  1630.  Swanson, J. W.; Dugal, 11. S.; Buchanan. M . A . ; Dickey, E . IC. KRAFT EFFLUENT COLOR CHARACTERIZATION B E F O R E A N D A F T E R STOICHIOMETRIC LIME T R E A T MENT. Envir. Protection Technol. Ser. EPA-R2-73-14 1: 75 p. (Feb., 1973). [GPO, Supt. D o c , Washington, D.C. 20402; SI.00j  The NCASI lime trmt. process was round to remove an av. ot" ca. 86% of the color, 57% of the total org. C, and 17% of total sugars from unbleached kraft mill effluents collected at Rieeboio, Ga., over a 15-month period and processed at Appleton, Wis. No appreciable change in chloride content was noted. The wt.-av. mol.wis. of the untrd. jcid-insol. fractions varied from less than 400 to ca. 30,000: the mol.wts. of the untrd. acid-sol., lime-trd. acid-insoL, and lime-trd. acid-sol. fractions varied from below 400 to ca. 5000. The study showed that color bodies having an apparent mol.wt. below 400 are not removed, but those having mol.wts. above 5000 are completely removed. In the 400-5000 mol.wt. range, partial removal takes place. Based on IR spectry., the acid-insol. color bodies of high mol.wt. seem to contain a high proportion of C O groups, probably conjugated with an aromatic ring, while the low mol. acid-sol. fractions seem to contain noneonjugatcd C O O H groups assocd. with carbohydrates. Color bodies are aromatic cpds., partly degraded lignin, having a neg. charge and existing primarily as sol. Na salts in aq. solus. The color bodies which are not removed by lime trmt. have low mol.wt., high unconjugated COOH groups, lisminlikc character, and seem assocd. with colorless C cpds. 18 ref. " C.L.B.  11801. Gould, M . COLOR R E M O V A L FROM K R A F T MILL E F F L U E N T B Y A N IMPROVED LIME PROCESS. Tappi 56, no. 3: 79-82 (March, 1973); cf. AB1PC 41: abstr. 10544; 43: abstr. 3028, 8487.  1626.  Spruill, E . L . COLOR R E M O V A L A N D SLUDGE T O T A L MILL E F F L U E N T . Tappi 56, no. 4: 98-100 (April, 1973).  RECOVERY  FROM  A lime trmt. color removal system, with recovery of lime and fibrous sludge integrated into the kraft lime processing system, has been constructed for trmt. of total mill effluent at the unbleached kraft mill of Continental Can Co., Hodge, La. With about 1000 ppm of lime, color redn. of 80-90% has been achieved in kraft effluent, with lower effectiveness on neutral sulfite chem. wastes. Good centrifugal dewatering and lime kiln incineration of sludges have been recorded. Settling and thickening of color sludge have been excellent, but carbonation-stage settling has been more variable. 8 ref. " C.L.B.  1G32(M). Tinipo. W. C ; Lanrt. 1". \V. A C T I V A T E D C A R l . O N 'I R E A T M E N T 01" U N B L E A C H E D K RAIT EFFLUENT FOR R E U S E : PILOT PLANT RESULTS. TAI'Pl Envir. Conf. (San Francisco), May 1973: 203-1S. An earlier lab. study at St. Regis Paper Co.'s R&D Div. (Pensacola, Fla.) established the degree of effluent trmt. achievable with activated C alone and combined with other method*. It also helped to pick the best of 24 activated C prepns., and ascertained tiiat McOH and other low-niol. org. cpds. are not removable by activated C. The. present rept. gives cxptl. and operating data tor a 30 gal./min. pilot plant in which 3 different pretrmts. (clarification, clarification plus lime trmt., and biooxidn. plus clarification) preceded the adsorptive removal of effluent components in 2 different systems. One system utilized 4 std. downtlow granular C columns, the other involved multistage countercurretit agitation ( F A C E T system, short for "line activated carbon effluent trmt."). The lime/C sequence achieved color removals to below 100 A P H A color units and T O C removals to less than 100 mg./liter. It was the most econ. of the 3 sequences studied. Optimum chem. dosaaes were 320-600 mg. of CaO/liter plus 2.5 lb. of C/1000 gal. For successful trmt. with activated C, tiic unbieached kraft effluents must contain ca. 80 mg. of Ca/liter. The other 2 sequences yielded rel. low adsorption rates, probably due to coagulation of colloidal color bodies on the C surface. The F A C E T system was found to be tech. sound and capable of further devt. to provide trmt. at lower capital cost than with conventional C columns. 17 ref. C.L.B.  1640(M). Wright, R. S. C O L O R R E M O V A L F R O M K R A F T PULP M I L L E F F L U ENTS HY MASSIVE LIME T R E A T M E N T . TAPP1 Envir. Conf. (San Francisco), May 1973: 229-35. Massive lime trmt. by the NCASI-dcvd. process will remove over 90% of color bodies from eflluents of the final unbleached kraft pulp washing stage and of the alk. extn. stage in bleach plants. These 2 effluents contain 65-75% of the total coior load produced in the mfr. of bleached kraft pulp. Using all the lime normally available in a typical bleached kraft mill, ca. 14%. of the total effluent can be trd. Dy trg. the most highly colored eflluents, 72% of the mill's total color load can be removed. The introduction of massive lime into the mill's liquor causticizing operation will dil. the white liquor and lower its concn. by ca. 15%. Hence the total liquor vol. handled throughout the mill will inciease and require increased capacity of chem. prepn. and recovery equipment. For a given pulp prodn., lime kiln fuel requirements inciease 6.4%. Moreover, the carryover of org. cpds. by the massive lime sludge into the cooking liquor system can intensify foam problems. Buildups of CI and other matls. have no apparent effect on the chem. recovery cycle. A typical 1000 t./day kraft mill may spend ca. Sl.SO/t. of bleached pulp for massive lime trmt. of 4,000,000 gal. effluent, without adverse effect on pulp bleachability or final prod, quality. C.L.B.  5110.  Sanks. R. L. ION-l-:XCllANGL COLOR AND MINERAL REMOVAL PROM KRAFT HLEACH WASTES. U.S. EPA, Envir. Prot. Technol. EPA-R2-73-25S: 201 p. (May, 1973). [Supt. Doc, GPO, Washington, D.C. 20402; S2.35) ;  Laboratory evalns. of 20 ion-exchange resins and 7 carbons for removing color and minerals from kraft bleach plant effluent showed that the resins were equal !•> carbon for decoloring the combined waste. With few exceptions, resins were unsuited for decoioring wastes from each stage separately. Except for success in the use of weak wash to regenerate Amberlite XAD-8 resin, utilization ofmill liquors for regeneration was unsuccessful. Sulfuric acid, NaOH, and ammonia were good regenerants, but lime was poor. Single stage ion-exchange produced water adequate for unbleached pulping while two-stage desalination produced water adequate for bleached pulping. The costs for desalination incl. amortization over a 10 yr. period are wtd. to vary from SI.38/1000 gal. (for the nonoptimized lab. process) to S0.42/1000 gal. (with estd. 90% cation regeneration efficiency, 85% anion regeneration efficiency, and 87% prod, recovery). 63 ref. W.W.  (See also abstr. no. 5615, 5642) 5649.  Croom, H. C.;Owens-Illinois Inc. SYSTEM EOR REMOVING COLOR FROM PAPER MILL LIQUID WASTE. U.S. pat. 3,736,254. issued May 29, 1973. 7 claims.  Liquid pulping effluent is mixed with an aq. slurry of lime and lime mud composed principally of calcium carbonate, under alk. conditions. The mixt. is subjected to clarification sepn. of formed precipitanls. The liquid effluent overflow is carbonated by bubbling carbon dioxide gas through it to ppt. calcium carbonate and residual color-imparting entities and to effect adjustment of the.pH to approx. neutral. The decolorized liquid is ready for discharge. FJ.L.  8534.  Pulp & Paper International. COLOR REMOVAL PROCESS. Pulp Paper Intern. 15, no.5: 69 (May, 1973).  PPR1C has successfully tested a new method for decolorizing pulp mill effluents which was originally developed and patented at the Centre Technique of France. The principal color-earn ing effluent streams from a pulp mill are contacted with high molecular weight amines dissolved in a water immiscible solvent. The nroccss is said to remove 90-98%. of the color, 45-85% of the COD, and 30-70% of the liOD from the effluents. The amines can be regenerated and recirculated to the process. Small scale tests in a kraft mill gave results as good as laboratory trials. Assuming economic feasibility studies civc favorable results, the process will be relesled on a larger scale. " P.IU1.  15901V t. J o h n s o n , J . S., Jr.: Minium. R. E.: Moore. G. I:'. HYPKRFILTRATION .'REVERSE OSMOSIS) Oh KRAFT PULP MILL AND ULEACI! PLANT WASTES. TAPPI Envir. Com". (Sat:f raneisco), May 1973: 23743. Kraft mill eflluents ( b r o w n s t o c k wash water, decker and screen room wastes, and bleach jlar.t effluents') were subjeeicd to high-pressure In perfiliration f!.0.) through dynamic membranes of polyacrylate o n a hydrous Zn'JV) oxide subs'rate: to moderate-pressure ultrafiltration using low-talt-rejection membranes comprising single layers of hydrous ZrtlVfoxide or of neut. org. polymers; a n d to low-pressure filtration. Devatering of weak black liquor was also attempted. Compared to conwntional detachable CA membranes, f.uxes were considerably h h i i e t , and decontamination seemed adequate for reuse of many Curates. Moreover, filtration could he conducted at the temp, of the process, and the membranes could be regenerated or removed and B a n n e d in situ. 24 ref. C.L.B.  10265. Kemmer, F. N.; Nalco Chemical Co. COLOR REMOVAL PROCESS. Can. pat. 929,712. Issued July 10, 1973. 4 claims. This process for decolorizing paper mill waste with lime is similar to that described previously in U.S. pat. 3,578,587; cf. ABIPC 42: abstr. 4034. F.J.L.  7911.  Fremont, H. A.; United States Plywood-Champion Papers Inc. COLOR REMOVAL FROM KRAFT MILL AQUEOUS EFFLUENTS. U.S. pat. 3,758,405. Issued Sept. 11, 1973. 10 claims.  A system is provided for removing color bodies from aq. effluents from kraft pulp mfr. such as first stage caustic extn. filtrate. The system involves adjusting the pll of the effluent to about 9, subjecting the effluent to ultrafiltration to form an aq. permeate and a rctcntatc contg. all the color bodies in a solids concn. of at least 15%, and thermally oxidg. the rctcntatc to oxidize the color bodies to colorless inorg. salts and gases which can be safely disposed of. F.J.L.  

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