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Organic-iron removal from water supplies Wetter, Robert Dale 1974

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ORGANIC-IRON REMOVAL "?RCK WATER SUPPLIES b y R.D. Wetter, P. Eng. B. Sc . , University of Alberta, 1966 A THESIS SUBMITTED IN PARTIAL FUL?ILJiENT OF THE REQUIREMENTS ? 0 R THE DEGREE OP MASTER C w APPLIED SCIENCE in the Department of C i v i l Engineering IVe accept this thesis as conforming to the required standard THE UNIVERSITY V* BRITISH COLUMBIA August, In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It i s understood that copying or p u b l i c a t i o n of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department The University of B r i t i s h Columbia Vancouver 8, Canada Date ABSTRACT The purpose of the study was to determine i f resins or activated carbon presently used to remove organic color from water supplies would also remove organically bound iron. The resins studied were Amberllte IRA 9 0 ^ , Duolite S-37» Dowex 11 and Amberlite IRA 4-98. The activated carbon used was Atlas Darco. Solutions of fulv lc ac id , fulv ic acid- iron and humic acid- iron were passed through the resin columns. Amberlite IRA 904, Duolite S-37 and Atlas Darco activated carbon effectively removed (100$ removal) fu lv lc acid but l i t t l e fu lv ic acid- iron or humic acid- iron (35% and $% respectively) . Dowex 11 and Amberlite IRA 4-98 were less effective in removing fulvic acid than IRA 904, Duolite S - 3 7 and activated carbon, and would not remove fu lv ic acid- iron or humic ac id- iron. A simple test for organically bound iron was developed and i t was found that iron-organic interactions were time dependent. Humic acid-iron reactions were very quick (approximately 4 hours) while fulv ic acid- iron reactions were much slower (15 days required for 57% of the iron to be strongly bound). It was found that a strongly bound fulv ic acid- iron solution acts very much l ike a humic acid- iron solution precipitating at a pH of less than 4 . 7 and that the color increases considerably as the solution ages and the organic-iron binding becomes stronger. i i TABLE OP CONTENTS Page ABSTRACT U TAB'LE OP CONTENTS i i i LIST OP TABLES v i LIST OP FIGURES v i i ACKNOWLEDGMENTS v i i i SECTION 1 INTRODUCTION 1 2 LITERATURE REVIEW 5 2.1 Water Soluble Organic Acids 5 2.2 Organic Acid-Iron Complexes ......... 9 2.3 Organic Color and Iron Removal from Water 10 2.3.1 Color Removal by Coagulation.... 12 2.3.2 Oxidation and F i l t r a t i o n 1^ 2.3.3 Ion Exchange and Adsorption Resins 16 2.3.4-Activated Carbon 17 3 PROBLEM APPROACH AND MATERIALS USED 19 3.1 Problem Approach 19 3.2 Resins and Activated Carbon used .... 20 3.3 D e f i n i t i o n of Organically Bound Iron 26 3.^ Preparation of the Organically-Bound Iron Solution 27 3.5 Test Preparations 2? i i i SECTION Page 4 HUMIC-IRON REMOVAL FROM AQUEOUS SOLUTION 3 3 4.1 Experiment #1 Humic-Iron Removal wi th . . . Recommended Regenerating Solution 3 3 4.2 Experiment #2 Humic-Iron Removal wi th . . . Experimental Regenerating Solutions 3 7 5 FULVTC-IRON REMOVAL FROM AQUEOUS SOLUTION.... 4 l 5.1 Experiment #1 Fulvic-Iron Removal Efficiency 41 5.2 Experiment #2 Regeneration Cycle Suitable for Fulvic-Iron Removal 50 6 FULVIC-IRON SOLUTION CHANGE WITH AGE 56 6.1 Experiment Description 56 6.2 Experiment Procedure 57 6.3 Experimental Results 5 9 Fulvic Acid Removal by Resins 5 9 Fulvic Acid-Iron Removal by Resins 65 Iron Elution Efficiency for Resins #3 and #4 7 1 Fulvic and Fulvic-Iron Removal by Activated Carbon 7 4 Fulvic Acid-Iron Color Increase 7 8 Fulvic Acid Change to Humic Acid in the presence of Iron 78 7 SUMMARY AND RESULTS 84 8 CONCLUSIONS 8 8 Bibliography 8 9 iv Page Appendix 1 Preparation of Humic and Hymatomelanic Acids 93 Appendix 2 The Complexation of Humic Acid to Iron 9^ Appendix 3 Complexation of Fulvic Acid To Iron 100 v LIST OP TABLES Table T i t l e Page I Humic-Iron Removal by Resins, Activated Carbon and Manganous Greensand 35 II Humic-Iron Removal by Experimentally Regenerated Resins 3 9 III Iron Removal from Fulvic-Iron Solution 4 4 IV Fulvic-Iron Elution Efficiency 5 3 V Fulvic-Iron Removal Efficiency 55 VI Fulvic Acid Feed Solution 6 4 VII Resin # 1 Fulvic Effluents 6 4 VIII Resin #2 Fulvic Effluents 6 4 IX Fulvic-Iron Feed Solution 6 6 X Resin #3 Fulvic-Iron Effluents 6 6 XI Resin # 4 Fulvic-Iron Effluents 7 0 XII Fulvic-Iron Effluent from Dowex 5 0 W - X 8 and Manganous Greensand.. . . . 7 0 XIII Percent Iron Eluted-from Resins #3 and'#4 . 7 4 XIV Activated Carbon Effluents 7 5 XV Organic Acid Fractionation 8 0 v i LIST OP FIGURES Fig u r e T i t l e Page 1 Resin Column Apparatus 2 9 2 F u l v i c - I r o n Color Removal "by Resins, A c t i v a t e d Carbon and Manganous Green-sand ^3 3 Color Change as F u l v i c - I r o n S o l u t i o n Ages ^6 4- Color Passed by IRA 90b R e s i n as F u l v i c -I r o n Ages ^7 5 Aged F u l v i c A c i d and IRA 904- E f f l u e n t Color. ^ 9 6 F u l v i c E f f l u e n t Color from Resin #1 60 7 F u l v i c E f f l u e n t Color from Resin #2 61 8 F u l v i c E f f l u e n t and F u l v i c I r o n E f f l u e n t on day 33. 63 9 F u l v i c - I r o n E f f l u e n t Color from R e s i n #3 66 10 F u l v i c - I r o n E f f l u e n t C olor from Resin 67 11 F u l v i c - I r o n E f f l u e n t Color by Dowex 50W-X8 and Manganous Greensand 7 2 12 F u l v i c - I r o n E f f l u e n t Color on day 3 3 7 3 13 F u l v i c Color Removal by A c t i v a t e d Carbon.... 76 l*f F u l v i c - I r o n E f f l u e n t Color by A c t i v a t e d Carbon 77 1 5 Color of F u l v i c and F u l v i c - I r o n S o l u t i o n s . . . 7 9 16 P r e c i p i t a t e d F u l v i c - I r o n A f t e r 3 3 days Aging, 8 1 17 Schematic Diagram of F r a c t i o n a t i o n Procedure • • • • 9 ^  v i i ACKNOWLEDGMENTS Acknowledgment is extended to the National Research Council for providing an assistantship to carry out this research. v i i i SECTION 1 INTRODUCTION For many c e n t u r i e s , d i s s o l v e d i r o n has created a problem i n municipal and i n d u s t r i a l water s u p p l i e s . The i r o n may be present as a f e r r o u s or f e r r i c complex, w i t h water or some s u b s t i t u t e d l i g a n d . The United States P u b l i c Health Service sets a recommended maximum l i m i t of 0 . 3 mg/l of i r o n as being e s s e n t i a l t o make water a e s t h e t i c a l l y acceptable and potable. I r o n concentrations above t h i s value cause the d e t e r i o r a t i o n of water q u a l i t y due to the formation of f e r r i c hydroxide by the o x i d a t i o n of f e r r o u s t o f e r r i c i r o n i n the presence of d i s s o l v e d oxygen'. Color and r u s t - s t a i n i n g problems may occur as a r e s u l t . I r o n b a c t e r i a are a l s o encouraged to grow at concentrations above 0 . 3 mg/l, and t h i s growth may r e s u l t i n water q u a l i t y problems such as: 1. Taste and odor caused by decaying b a c t e r i a . 2. Rust s t a i n i n g problems caused by the p r e c i p i t a t i o n of f e r r i c hydroxide by t h e - i r o n b a c t e r i a . 3 . F o u l i n g and clo g g i n g of water l i n e s due to the mass of b i o l o g i c a l growth. 4. Formation of red or black b i o l o g i c a l sludge which may break f r e e of pipes and come out the user's water taps. 2 G e n e r a l l y , Iron b a c t e r i a are thought to o x i d i z e the f e r r o u s i r o n to f e r r i c i r o n and e f f e c t the p r e c i p i t a t i o n of f e r r i c hydroxide. This o x i d a t i o n procedure i s thought to provide the energy f o r growth of the i r o n b a c t e r i a . The s t r i c t l y a u t o t r o p h i c i r o n b a c t e r i a such as G a l l l o n e l l a f e r r u - glnea are b e l i e v e d to depend t o t a l l y on t h i s r e a c t i o n , w h i l e the f a c u l t a t i v e i r o n b a c t e r i a such as L e p t o t h r l x or C r e n o t h r l x  polyspora can apparently grow by the above r e a c t i o n or by the decomposition of organic compounds. The exact mechanism by which i r o n b a c t e r i a d e r i v e t h e i r energy from the o x i d a t i o n of f e r r o u s to f e r r i c i r o n i s not understood. I r o n b a c t e r i a are lyrically a e r o b i c , filamentous water organisms which accumu-l a t e l a r g e amounts of f e r r i c hydroxide around t h e i r c e l l s . This f e r r i c hydroxide may be present i n amounts many times g r e a t e r than the b a c t e r i a l c e l l m a t e r i a l . Starkey ( 3 ) found th a t i r o n b a c t e r i a were able to s u r v i v e i n water ranging i n temperature from 0 GC to 32°C, could l i v e at very low d i s s o l v e d oxygen l e v e l s and were r e l a t i v e l y i n s e n s i t i v e to l i g h t . Thus, they were very adaptable to l i v i n g i n pipes. The b a c t e r i a have been observed growing i n water w i t h an i r o n content as low as 0.3 mg/1. C l a r k , S c o t t , and Bone ( 1 ) have c a r r i e d out experiments which i n d i c a t e that a t l e a s t three of the h e t e r o t r o p h i c b a c t e r i a normally encountered i n water (Aerobacter aerogenes, S e r r a t l a i n d i c a , and B a c i l l u s pumllus) have the c a p a b i l i t y of us i n g an 3 organic acid- iron complex as a food source and w i l l precipitate the iron out as a rusty stain. Starkey ( 3 ) has presented the results of Molisch and Cataldi which show that many iron bacteria are able to grow on organic materials and that there is reason to believe that these bacteria destroyed the organic ac id , which then led to the precipitation of the iron as f err ic hydroxide. Prom the foregoing discussion, i t can be seen that bacteria can exist in the presence of ferrous iron and organi-cally-bound iron and that either may act as the energy source for the bacteria. By maintaining a chlorine residual , the problems caused by bacterial growth can be removed. The water is s t i l l aesthetically displeasing, however, due to color, rust staining, and an iron content which is higher than that recommended by U.S.P.H.S. standards. Problems caused by f err ic hydroxide and bacterial growth can be controlled by removing the ferrous iron and the organic-iron from the water supply. There are several successful methods for removing iron in the ferrous or f err i c form from water supplies. Aeration of the water followed by sedimentation and f i l t r a t i o n is the most common method. The high dissolved oxygen content attained by aeration causes the ferrous ion to be oxidized to the f err i c ion which is re lat ively insoluble in water and precipitates as f e r r i c hydroxide. The f err i c hydroxide is allowed to settle 4 and the water i s then f i l t e r e d to remove the remaining suspended p a r t i c l e s of f e r r i c hydroxide. -Cation exchange r e s i n s have been used to remove f e r r o u s i r o n , e s p e c i a l l y when the removal of calcium and magnesium i s a l s o r e q u i r e d . When the i o n exchange process i s used, i t i s important t h a t the water be kept at a low d i s s o l v e d oxygen content to ensure t h a t the f e r r o u s i o n i s not o x i d i z e d to the f e r r i c form, as p r e c i p i t a t e d f e r r i c hydroxide tends to f o u l the r e s i n beds. A t h i r d method commonly used to remove f e r r o u s i r o n i s a contact f i l t r a t i o n method us i n g manganous z e o l i t e or green-sand. In t h i s method the i r o n i s removed by o x i d a t i o n and f i l t r a t i o n w h i l e passing through a bed of manganous greensand. When organic a c i d s are present i n water together w i t h i r o n , an organic a c i d - i r o n complex i s formed which i s much more s o l u b l e than f e r r i c i r o n . This complex i s o f t e n r e f e r r e d to as organically-bound i r o n . I r o n i n t h i s form cannot u s u a l l y be removed by any of the above methods. The removal of o r g a n i -cally-bound i r o n from water s u p p l i e s has been found to be very d i f f i c u l t , and many communities and s i n g l e d w e l l i n g s l i v e w i t h the o r g a n i c - i r o n problem because they cannot a f f o r d to r e c t i f y the s i t u a t i o n . I t i s the purpose of t h i s study to determine whether a c t i v a t e d carbon or the newly-developed organic scavenger r e s i n s w i l l remove the organic a c i d - i r o n complex from water s u p p l i e s . SECTION 2 LITERATURE REVIEW 2 . 1 WATER SOLUBLE ORGANIC ACIDS Colored organics i n water are thought to o r i g i n a t e from a multitude of organic m a t e r i a l s present i n f o r e s t v e g e t a t i o n and s o i l . The c l a s s i f i c a t i o n of organic a c i d s i n c o l o r e d water as given by Black and Christman (2) and other I n v e s t i g a t o r s (39) are f u l v i c a c i d , humic a c i d and hymatomelanic a c i d . The f r a c t i o n a t i o n procedure i s shown i n Appendix 1, and provides the f o l l o w i n g f r a c t i o n s i 1. E t h e r - s o l u b l e f a t s and waxes are removed i n a separa-t o r y f u n n e l . 2 . F u l v i c a c i d i s described as being that p o r t i o n of organic c o l o r which i s water s o l u b l e at pH=l. 3 . Humic a c i d and hymatomelanic a c i d are water i n s o l u b l e at pH=l. Therefore they p r e c i p i t a t e a t pH=l and can be separated from the water s o l u b l e f u l v i c a c i d p o r t i o n . 4. Hymatomelanic a c i d i s described as being s o l u b l e i n e t h y l a l c o h o l , while humic a c i d i s not. This f r a c t i o n a t i o n procedure i s q u i t e crude, but i s the procedure most widely reported i n the l i t e r a t u r e . Black and Christman (2) found t h a t f u l v i c a c i d s are aromatic polyhydroxy methoxy c a r b o x y l i c a c i d s . The equivalent 5 6 weight of f u l v i c a c i d was determined as "being between 89-1 3 3 per equ i v a l e n t . Shapiro (4) has reported an average molecular weight of 4 5 6 on the b a s i s of isothermal d i s t i l l a -t i o n data. T i t r a t i o n i n aqueous systems i n d i c a t e d an average equivalent weight of 228. Oldham (5) r e p o r t s a molecular weight of 640 f o r the humic and hymatomelanic a c i d p o r t i o n s , w i t h the average equivalent weight being 222. In l a t e r work wit h the use of Sephadex g e l s e p a r a t i o n columns, Christman (43) discovered molecular weights ranging from 700 to 10,000 f o r the m a j o r i t y of c o l o r molecules. H a l l (15) r e p o r t s molecular weights from 700 to 50,000 f o r the co l o r e d organics i n Lake Mary, Wisconsin. He used Sephadex g e l columns to separate the v a r i o u s molecular weight f r a c t i o n s and found that only about k% of the col o r e d organics i n Lake Mary had a molecular weight of l e s s than 700. Prom t h i s d i s c u s s i o n , i t may be seen t h a t the molecular weight of the water s o l u b l e organic a c i d s v a r i e s widely. I n p a r t , t h i s may be due to the amount of m i c r o b i a l degradation of the organic molecule t h a t has occurred before sampling. A widely-reported property of co l o r e d water i s the v a r i a -t i o n of c o l o r i n t e n s i t y w i t h a v a r i a t i o n i n pH. S l n g l e y , H a r r i s and Maulding (6) have developed a nomograph which converts u n i t s of c o l o r a t any pH to u n i t s of c o l o r at pH=8.3. As the pH increases so does the c o l o r i n t e n s i t y . This i s a l s o documented by Christman and Ghassemi (7), although they s t a t e that pH and c o l o r v a r i a t i o n s are not the 7 same f o r every c o l o r e d water. The chemical formulae of f u l v i c , humic and hymatomelanic acid s appear to be r a t h e r e l u s i v e . Some authors such as Burges (8) b e l i e v e that humic a c i d i s e i t h e r a s i n g l e chemical substance or a group of very s i m i l a r substances. Most authors b e l i e v e that the composition of these c o l o r molecules i s dependent on the source, the manner of e x t r a c t i o n and the formation time of the organic substances. There may be a great many d i f f e r e n t chemical formulae f o r the va r i o u s organic molecules i n each of these a c i d groups. Christman and Ghassemi ( 7 ) subjected c o l o r e d organics i n s e v e r a l n a t u r a l streams to degradative chemical s t u d i e s using o x i d a t i o n w i t h a l k a l i n e CuO as the degrading technique. Seven degradation products of n a t u r a l organic c o l o r were i d e n t i f i e d : V a n i l l i n , V a n i l l i c a c i d , S y r i n g i c a c i d , Catechol, R e s o r c i n o l , Protocatechnic a c i d and 3,5-dihydroxy-Benzolc a c i d . According to Christman and Ghassemi ( 7 ) , other I n v e s t i g a t o r s (9,10) have found the same products In degraded s o i l humic a c i d . H a l l ( 1 5 ) subjected both c o l o r e d organics from Lake Mary and s o l u b l e l e a f e x t r a c t to chemical degradation s t u d i e s . Both the a l k a l i n e CuO o x i d a t i o n procedure and the Na-Hg r e d u c t i v e procedure were used i n these s t u d i e s . He discovered the same degradation products as Christman and a l s o seven more, c o n s i s t i n g of p-Methylphenol, o-Methoxyphenol, Benzoic a c i d , 3-4-Dehydroxybenzoic a c i d , p-Hydroxybenzole a c i d , d i b u t y l 8 Phthalate and p-Hydroxyacetophenone. He a l s o discovered that d i f f e r e n t molecular weight f r a c t i o n s o f organic c o l o r (separated by Sephadex g e l columns) were chemically s i m i l a r compounds, d i f f e r i n g mainly i n molecular s i z e . H a l l concluded t h a t b e t t e r degradative techniques and more understanding of these techniques would be r e q u i r e d beforecne could i d e n t i f y a l l the chemical subunits and the groups which p a r t i c i p a t e i n l i n k i n g the subunits to form the organic molecules. Since organic c o l o r molecules are of a very complex chemical nature and t h e i r i d e n t i f i c a t i o n and se p a r a t i o n i s at present i m p o s s i b l e , the s e p a r a t i o n techniques used to c l a s s i f y them as f u l v i c , humic, and hymatomelanlc acids appear to be a l l we can do a t present. Of the three groups, W i l s o n ( 1 1 ) s t a t e s t h a t f u l v i c a c i d i s the most water s o l u b l e f r a c t i o n of n a t u r a l s o i l humus and would be expected to be found i n n a t u r a l waters i n higher concentrations than e i t h e r humic or hymatomelanlc a c i d s . This i s borne out by Black and Christman ( 2 ) who found t h a t f o r 10 d i f f e r e n t water samples, the average percentage of a c i d s was f u l v i c 87%i humic 2% and hymatomelanlc 1 1 $ . Christman and Ghassemi (?) have i n d i c a t e d t h a t no r e l a t i o n s h i p between organic carbon content and c o l o r could be found f o r the s e v e r a l waters examined. Black and Christman ( 1 2 ) performed chemical analyses on nine d i f f e r e n t waters and found no c o r r e l a t i o n between organically-complexed i r o n and c o l o r , and no c o r r e l a t i o n between C.O.D. and c o l o r . They a l s o found t h a t B.O.D. values 9 were extremely low i n a l l samples, which suggests t h a t i f the organic substances causing c o l o r i n water are products of m i c r o b i o l o g i c a l decomposition, they are i n t h e i r f i n a l s t a t e or may only be f u r t h e r decomposed by s p e c i a l i z e d b a c t e r i a . In an a n a l y s i s of 32 l a k e waters, Christman ( 1 7 ) found th a t a l l c o l o r c o l l o i d s were n e g a t i v e l y charged. Making use of t h i s phenomenon, Black and Christman ( 1 2 ) used e l e c t r o -d i a l y s i s c e l l s and membrane f i l t e r s to determine that most c o l o r c o l l o i d s ranged between 3-5 mji/ and 10 mju i n diameter. They used l i g h t - s c a t t e r i n g experiments which i n d i c a t e d that the c o l o r In t h e i r water was i n the form of c o l o r c o l l o i d s . Other i n v e s t i g a t o r s have concluded that the c o l o r i n water i s made up of organic molecules i n true s o l u t i o n . At such a aaaTlsize range, i t i s probably q u i t e d i f f i c u l t t o t e l l whether the c o l o r i s made up of l a r g e organic molecules i n tr u e s o l u t i o n or an organic c o l l o i d s ! 2.2 ORGANIC ACID-IRON COMPLEXES Many d i f f e r e n t complexing p o s s i b i l i t i e s have been put forward by v a r i o u s authors. Babcock ( 1 3 ) b e l i e v e s that i r o n can be h e l d i n s o l u t i o n by " p r o t e c t i v e organic c o l l o i d s " . In s t u d i e s of the o x i d a t i o n r a t e of i r o n i n aerated ground waters, Ghosh (14) i n d i c a t e s that organic matter may ch e l a t e f e r r o u s and f e r r i c i o n s . In Faust and Hunter's book ( 3 9 ) . p. 2 4 5 , i t i s suggested that metal chelates w i t h organic l i g a n d s 10 are much more s t a b l e i n d i l u t e s o l u t i o n s than are metal organic complexes. 1 Shapiro (4, 16, 3 9 ) i n a s e r i e s of experiments concludes th a t i r o n p r e c i p i t a t e s may be peptized by ad s o r p t i o n of o r g a n i c s . Oldham ( 5 ) i n d i c a t e s that the organic molecules and f e r r i c i r o n are i n tr u e s o l u t i o n w i t h an e q u i l i b r i u m constant of 1.46 x 10^ at pH=2. I n Paust and Hunter's book ( 3 9 ) , S c h n i t z e r p. 3 0 8 found t h a t l s l molar s o l u t i o n s of F e + 3 o r A l + - ^ t o f u l v i c a c i d complexes were completely water s o l u b l e , 2:1 complexes were l e s s s o l u b l e and 6:1 complexes were water i n s o l u b l e . Thus I t may be seen that much experimental work has been done. However, when considered as a whole, the r e s u l t s are i n c o n c l u s i v e . The mechanism of complexation may be any one or a combination of a l l the above methods. 2.3 ORGANIC COLOR AND IRON REMOVAL PROM WATER There appear to be f o u r d i s t i n c t methods f o r removing organic c o l o r from water s u p p l i e s . These methods are co-a g u l a t i o n , o x i d a t i o n by a strong oxidant, and Ion exchange or a d s o r p t i o n by r e s i n s or a c t i v a t e d carbon. The f o l l o w i n g 1 Metal organic complexes are formed by the normal exchange of e l e c t r o n s and e l e c t r o s t a t i c bonding and the s t a b i l i t y of the complex i s measured by i t s e q u i l i b r i u m constant. Metal chelates were described as organic complexes i n which metal ch e l a t e r i n g s were formed and the s t a b i l i t y of the complex depended on the number of metal chelate r i n g s present. 11 d i s c u s s i o n w i l l make apparent why these methods would be considered i n the removal of o r g a n i c a l l y bound i r o n from water s u p p l i e s . I n the c o a g u l a t i o n method, f e r r i c and aluminum s a l t s are used as the coagulants t o remove c o l o r . Prom the J o i n t Report on Coagulation and Color Problems (24), there appear to be two b a s i c t h e o r i e s of c o a g u l a t i o n f o r c o l o r removal. The f i r s t i s a p h y s i c a l mechanism based on double l a y e r 3+ 3+ compression. I t i s thought t h a t the A l . or Fe - or t h e i r h y d r o l y s i s products a c t on the n e g a t i v e l y charged c o l o r c o l l o i d s to d e s t a b i l i z e them and n e u t r a l i z e the negative charge. By t h i s theory, o r g a n i c a l l y bound i r o n should be removed w i t h the coagulant as the organic i r o n c o l l o i d s should c a r r y a sma l l e r negative charge than the o r i g i n a l organic c o l l o i d s . I n recent s t u d i e s , however, t h i s theory has been found to break down i n s e v e r a l cases. A second theory has been put forward supporting s p e c i f i c chemical r e a c t i o n s at the c o l o r -s o l v e n t i n t e r f a c e between the coagulant and the or g a n i c s . I n t h i s case, the i r o n may cause i n t e r f e r e n c e w i t h t h i s chemical r e a c t i o n and the e f f i c i e n c y of c o l o r and o r g a n i c - i r o n removal may be a f f e c t e d . Organic c o l o r has been removed from water s u p p l i e s by thekme of a stro n g o x i d i z i n g agent which o x i d i z e s the organic to 0 0 3 . When o r g a n i c a l l y bound i r o n i s present, t h i s method has a l s o been used w i t h subsequent f i l t r a t i o n of the o x i d i z e d f e r r i c compound by e i t h e r sand f i l t e r s or manganous greensand f i l t e r s . 12 The strong oxidizing agents which have been t r i e d are potassium permanganate, chlorine and ozone. The ion exchange or the adsorptive properties of various resins and activated carbon have been used to remove color from water supplies. Fouling problems occurred i n the past, but with the development of new organic scavenger resins, t h i s method i s becoming p r a c t i c a l . I t has been suggested that these resins w i l l also remove organically bound i r o n . A l l the above methods have t h e i r own p a r t i c u l a r problems and these w i l l be discussed i n d e t a i l In the following pages. 2. 3 . 1 COLOR REMOVAL BY COAGULATION The use of coagulants to remove color-causing organics has been quite thoroughly Investigated. This method appears to be the most widely used i n practice at the present time. A report by the Research Committee on Coagulation and Color Problems (24) states that "the choice of coagulant i s generally based on i n d i v i d u a l preference and economics, but i s p a r t i c u l a r l y l i m i t e d to aluminum and f e r r i c s a l t s . " These s a l t s include aluminum s u l f a t e , sodium alumlnate, f e r r i c s u l f a t e , f e r r i c chloride, and f e r r i c c h l o r o s u l f a t e . T h e 3 % 3 * e f f e c t i v e ions are the Al and Fe and t h e i r hydrolysis products. The pH range required f o r optimum color coagulation has been established by many investigators ( 2 5 , 2 6 , 24, 2 7 ) as being between pH=5 to 6 f o r Alum and pH=3.2 to 4.5 f o r the f e r r i c s a l t s . At the optimum pH, the best color removal i s 13 obtained f o r the s m a l l e s t amount of coagulant used. Maulding and H a r r i s (27) have shown that the optimum pH f o r f e r r i c coagulants changes s i g n i f i c a n t l y w i t h temperature and i o n i c environment. Calcium and sodium i n concentrations up to 200mg/l increase the e f f e c t i v e n e s s of c o l o r removal wi t h f e r r i c s u l f a t e and extend the pH range of good c o a g u l a t i o n upwards. In no case, however, i s the optimum pH extended past 4 . 5 . The presence of the c h l o r i d e i o n has no e f f e c t on the c o a g u l a t i o n of c o l o r , w h i l e the presence of the s u l f a t e i o n has a d e l e t e r i o u s e f f e c t on c o l o r removal. The optimum pH f o r c o l o r removal depends on the water temperature as w e l l as the raw water c o l o r . At a water temperature of 0°C the optimum pH w i l l be 0.5 higher than i t w i l l at 24°C. H a l l and Packman (28) s t a t e t h a t d i f f e r e n t r a t i o s of humic and f u l v i c a c i d f r a c t i o n s f o r v a r i o u s waters r e q u i r e d i f f e r e n t r a t i o s of coagulant to raw water c o l o r . I t i s g e n e r a l l y agreed t h a t the use of coagulants f o r c o l o r removal on s o f t , unbuffered surface waters i s q u i t e p r a c t i c a l . The cost of c o l o r removal increases s u b s t a n t i a l l y as the waters become more b u f f e r e d , due to the l a r g e r amount of a c i d r e q u i r e d to a d j u s t the pH t o the optimum value. This cost does not appear to be o f f s e t by an increase i n c o a g u l a t i o n e f f i c i e n c y caused by increased hardness i n the water. V i l a r e t (29) has shown that although organic c o l o r can be removed by the use of a c a t i o n i c p o l y e l e c t r o l y t e , i t would be uneconomical, as the amount r e q u i r e d i s p r o p o r t i o n a l to the 14 the total surface area of the species being removed. For organic color, the amount required is re lat ive ly great due to the very small part ic le size. Cationic, anionic and nonlonic polymers have been used successfully as coagulant aids to strengthen the floe formed with iron or aluminum salts . In summary, although coagulation is at present considered the best method for color removal, i t has many problems and may be quite expensive. 2 . 3 . 2 Oxidation and F i l t r a t i o n As mentioned previously, the use of a strong oxidant to change the organically bound iron complex to either C0 2 and Fe(OH)^ or CO2 plus organic and Fe(OH)^ has been suggested by several authors. Wiley and Jennlng (18) used a permanganate solution and a manganous greensand f i l t e r to oxidize and remove the organic iron complex. To achieve effective color and iron removal they found that a contact time of 5 to 20 minutes with the permanganate was necessary before the water was f i l t ered through the manganous greensand. The dosage of potassium permanganate and the contact time must be adjusted to suit the particular conditions of the water. These authors also experimented with chlorine as an oxidizing agent but found that the process was not efficient enough to be considered as a treatment process for the removal of organically bound iron. 1 5 According to Welch ( 1 9 ) , i f an overdose of permanganate i s added to the water supply i t tends to regenerate the manganous greensand, thus i n c r e a s i n g the l e n g t h of f i l t e r runs. He a l s o suggests that i f used c o r r e c t l y , there i s no p o s s i b i l i t y of any potassium permanganate reaching the d i s t r i b u t i o n system. Added b e n e f i t s i n the use of permanganate as noted by Welch are removal of a p o r t i o n of t a s t e and odor and the d e s t r u c t i o n of b a c t e r i a and v i r u s e s by the o x i d a t i o n process. As a d i s i n f e c t a n t however, i t has a disadvantage i n t h a t the manganous greensand removes, the r e s i d u a l and .therefore p o s t - c h l o r i n a t i o n i s r e q u i r e d . O'Donovan (37) found that ozone could be used economically f o r c o l o r removal. The ozone apparently o x i d i z e s the c o l o r p a r t i c l e s and breaks them down and i n so doing leaves a c l e a r e f f l u e n t . S e v e r a l l a r g e and s m a l l i n s t a l l a t i o n s i n Europe are using ozone f o r t h i s purpose. O'Donovan w r i t e s that other i n v e s t i g a t o r s (41 and 42) have discovered that i r o n and manganese i n other than very s m a l l amounts have a d e l e t e r i o u s e f f e c t on the removal of c o l o r by ozonation. I t i s thought that the ozonation process o x i d i z e s the i r o n and manganese to t h e i r i n s o l u b l e hydro-x i d e s , t h e r e f o r e i n c r e a s i n g the c o l l o i d a l c o l o r i n water. Other i n v e s t i g a t o r s are of the o p i n i o n t h a t i f ozonation i s f o l l o w e d by f i l t r a t i o n through manganous greensand, the i r o n and manganese w i l l be removed from the s o l u t i o n . The ozonation i s thought to break down the organic i r o n complex and o x i d i z e the i r o n w i t h subsequent removal of the i r o n i n the manganous greensand. 1 6 2 . 3 . 3 Ion Exchange and Adsorption Resins In the past, Ion exchange r e s i n s have been used to s o f t e n and demineralize water by the removal of c a t i o n s and anions. In these systems, problems have always been encountered w i t h organics such as humic and f u l v i c a c i d f o u l i n g the r e s i n beds. According to P r i s c h and Kunin ( 2 0 ) , the accumulation of these a c i d s on the r e s i n s l i m i t s the c a p a c i t y of the r e s i n s t o f u r t h e r exchange ino r g a n i c i o n s . Over a p e r i o d of time, the a c i d s d i f f u s e i n the r e s i n g e l and are t i g h t l y bound by Van der Waal's f o r c e s i n a d d i t i o n t o the normal i o n exchange f o r c e s . These organic a c i d s were found to be very d i f f i c u l t to remove from the r e s i n , the best e l u t a n t s o l u t i o n being warm b r i n e . However, even t h i s was not p a r t i c u l a r l y e f f i c i e n t . More r e c e n t l y , i t has been found that some of the anion exchange r e s i n s could e l u t e the organic a c i d s more e f f i c i e n t l y than others. This has l e d t o the development of organic t r a p or scavenger r e s i n s which are capable of removing organic a c i d s from s o l u t i o n and can be regenerated w i t h considerable e f f i c i e n c y . Abrams (21) i n d i c a t e s that weakly b a s i c macroporous phenolic anion exchange r e s i n s have good organic scavenging p r o p e r t i e s and w i l l probably have a p p l i c a t i o n i n the removal of c o l o r from water s u p p l i e s . In l a t e r r e p o r t s (22) ( 2 3 ) , Abrams has run l a b o r a t o r y and f i e l d t e s t s which appear to confirm that c o l o r may be removed from water by r e v e r s i b l e s o r p t i o n on macroporous h y d r o p h i l l c r e s i n s . In Faust and Hunter's book (39) p. 236, Gustafson and Paleos i n d i c a t e t h a t they obtained 7&% removal of f u l v i c a c i d from a 17 solution "by using an Amberlite XAD-2 anion res in . Their studies indicated thati 1. adsorption increases with increasing resin surface area; 2 . adsorption increases as water so lubi l i ty of the organic compound decreases} and 3. adsorption v ia hydrophobic bonding increases as the length of a hydrocarbon chain Increases or as the number of aromatic rings increases. Several investigators have used resins to concentrate the color in water before they fractionated i t into humic, fu lv ic and hymatomelanic acids to be used in laboratory analysis. No direct evidence has been found regarding the use of such resins for the specific purpose of removing organically bound iron from water supplies. It seems, however, that i t may be feasible and economical, especially in small instal lat ions. 2 . 3 . 4 Activated Carbon Activated carbon has long been used to remove organics and decolorize a variety of solutions. Activated carbon can be made from many carbonaceous starting materials. Some of these include coconut shel ls , peach p i t s , sawdust, wood char, f i sh , l igni te coal, coffee grounds, molasses, r ice hul l s , carbon black, peat, kelp and sugar ( 4 ) . The nature of the manufacturing processes used in the production of activated carbons remains 18 a closely guarded secret within the industry and is made up of the following variables: the nature of the starting material; the composition of the activation atmosphere (Og, C0 2 or H 20); and, the time and temperature of the activation process. With so many variables available to the manufacturer of activated carbon, i t is not surprising that a great many types of activated carbons exist and that a l l have different carbon adsorption surfaces. Many carbon users in the chemical industry appear to have adopted the philosophy of trying out various activated carbons, u n t i l they found one which suited their purpose best and then adopting this particular carbon and fore-going further investigation. One of the activated carbons most used in removing organics from water supplies appears to be made from l igni te coal and is produced by Atlas Chemicals under the trade name of Darco. Abrams ( 3 0 ) mentions using activated carbon to remove color from water and compares the results obtained using activated carbon with results using Duolite S-37, an organic scavenger anion exchange res in. Duolite S - 3 7 was found to be much more eff icient in color removal. Dr i sco l l ( 3 3 ) also used activated carbon from Atlas Chemicals in comparison with Amberllte IRA-458. Amberlite IRA-458 was found to be much more eff icient in color removal. Hager and Plentze ( 3 6 ) found carbon f i l t r a -tion effective in removing detergents, insecticides, viruses, specific chemical pollutants and taste and odor pollutants. SECTION 3 PROBLEM APPROACH AND MATERIALS USED 3 . 1 PROBLEM APPROACH Upon reviewing the problem of removing organically bound iron from water supplies, i t appeared that two approaches were possible! 1 . determination of the chemical nature of the organic acid- iron complex and then trying to develop a chemical or physical process which would remove this complex: or 2. use of a t r i a l and error procedure involving the presently popular water treatment methods for remvoing colored organic acids from water supplies. During the l i terature review i t became clear that the chemical nature of the natural organic acids in water is at best only part ia l ly known. The var iab i l i ty of the organic compounds makes their chemical determination very complicated and d i f f i c u l t . The addition of iron would probably increase this complexity. Another problem which would present i t se l f even i f one were able to determine a chemical formula for the organic acid-iron complex, would involve finding a removal mechanism. The mechanisms of substance removal by adsorption and absorption are not well understood and i t would probably be these mechanisms by which removal of organic iron from water occurs. This approach to the problem was thought to be very time-consuming and d i f f i c u l t due to the chemical complexity of the materials and removal mechanisms. 1 9 20 For the above reasons, and s i n c e a t present there are only a c e r t a i n number of water treatment processes which would be considered economically f e a s i b l e , the t r i a l and e r r o r approach to the problem was s e l e c t e d . The l i t e r a t u r e review on water treatment processes showed th a t a c t i v a t e d carbon and i o n exchange r e s i n s might be used to remove o r g a n i c a l l y bound i r o n from water s u p p l i e s q u i t e economically on a s m a l l s c a l e . I t was decided to t e s t some of the Ion exchange r e s i n s and a c t i v a t e d carbons p r e s e n t l y used i n t r e a t i n g water s u p p l i e s i n North America to see what l e v e l s of success could be achieved. 3.2 RESINS AND ACTIVATED CARBON USED I t was p r e v i o u s l y noted i n the l i t e r a t u r e review on i o n exchange r e s i n s t h a t organic scavenger r e s i n s have r e c e n t l y been developed which are capable of removing organic a c i d s from aqueous s o l u t i o n s . These p a r t i c u l a r r e s i n s have a l s o been found to e f f i c i e n t l y e l u t e the organic a c i d when a regener-a t i o n s o l u t i o n i s passed through them. The exact mechanism of organic a c i d removal appears to be i n some doubt. I n an attempt t o f i n d organic scavenger r e s i n s which might remove o r g a n i c a l l y bound i r o n e f f i c i e n t l y from water s u p p l i e s , the f o l l o w i n g companies were contacted: 1. Diamond Shamrock Chemical Company 2. Rohm and Haas Company of Canada L t d . 3. Alchem L t d . 4. Ionac Chemical Corporation. 21 These companies were requested to submit t e s t samples of t h e i r r e s i n s which they considered most l i k e l y t o be s u c c e s s f u l . The f o l l o w i n g r e s i n s were r e c e i v e d i n accordance w i t h that request: 1. D u o l i t e S-37 (Diamond Shamrock Chemical Co.) 2 . Amberlite IRA - 4 5 8 (Rohm and Haas Co.) 3. Amberlite I R A - 9 0 4 (Rohm and Haas. Co.) 4 . Dowex 1 1 (Alchem Ltd.) In the search f o r a c t i v a t e d carbon, A t l a s Chemicals was contacted and they agreed to supply Granular Darco a c t i v a t e d carbon f o r the purpose of t h i s experiment. D u o l i t e S-37 D u o l i t e S-37 i s a h i g h l y porous phenolic weak base adsorbent r e s i n s p e c i f i c a l l y designed to remove "organics" from water. Abrams ( 3 0 ) mentions t h a t more than f o r t y operating f i e l d i n s t a l l a t i o n s are using D u o l i t e S-37 to remove harmful organic matter p r i o r t o the d e i o n i z a t i o n of the water by other r e s i n s . The organics are removed i n order to a v o i d f o u l i n g problems i n t h e i r i o n exchange r e s i n s . This organic removal i s achieved without s i g n i f i c a n t change i n the ino r g a n i c composition of the water. D u o l i t e S-37 i s s a i d to be h i g h l y e f f e c t i v e i n the removal of humic, f u l v i c and hymatomelanlc a c i d s and t h e i r i r o n complexes. Some t e s t s conducted i n East Germany ( 3 1 ) i n d i c a t e t h a t the r e s i n i s more e f f e c t i v e i n i t s removal of c o l o r when i r o n i s a s s o c i a t e d w i t h the c o l o r . The 22 presence of iron resulted in a three to sevenfold Increase in the capacity of the resin to remove organics. The resin matrix consists of crosslinked phenol-formalde-hyde with the functional groups "being secondary and tertiary amines and phenolic hydroxyl. It has a service pH range of 2 to 8 and Is regenerated with a k-% sodium hydroxide solution. The resin is made up of l ight brown granules and adsorbs the organics rather than removing them by an ion exchange process. Water with high a lka l in i ty should not tend to shorten the l i f e of this resin as bicarbonate w i l l not be exchanged when the resin is in the hydroxide form. Amberlite IRA-4-58 Amberlite IRA-4-58 is a strongly basic anion exchange resin which derives i ts exchange act iv i ty from quaternary ammonium groups. This resin differs from other styrene-divinylbenzene resins in that i ts acrylic-based structure is more hydrophilic. Recent studies have revealed that ion exchangers with a relat ively hydrophilic resin structure show a lower a f f in i ty for organics than do those with a more hydrophobic structure. Thus the increased mobility of organics within the res in, resulting from a decrease in a f f in i ty , permits more rapid organic diffusion into the resin during the service cycle, and more rapid removal of organics during the regeneration cycle. The mechanism by which the color bodies are removed is thought to be one of adsorption rather than ion exchange. Due to its excellent adsorption and desorption properties, Amberlite IRA-4-58 in the chloride form is considered to be an excellent organic scavenger resin ( 3 2 ) . Amberlite IRA-458 2 3 is regenerated in this form by a 10% NaCl solution and has no pH l imitations. In an unpublished study comparing the effectiveness of seven different sorbents as organic scavengers, Dr i sco l l ( 3 3 ) found that Amberlite IRA-458 was more effective in removing organics than either Duolite S-37 or Amberlite IRA-904. In his experiment the colored organic solution was prepared from fulvic and humic acids and passed through the resin columns. Organic removal efficiency as measured by C.O.D. removal was as follows: % REMOVAL Amberlite IRA-458 80 Duolite S-37 72 Atlas Chemical Activated Carbon 6 5 Amberlite IRA-904 60 It should be pointed out that Amberlite IRA-458 is also an anion exchange resin and can be used as such in a conventional deionization system; in this case the regenerant is NaOH. Abrams ( 3 0 ) indicates that when a strong base anion exchange resin is used on colored water with.a high concentration of anions, the capacity to remove color is decreased due to competition of the anions for the exchange s i tes . This may indicate that Amberlite IRA-458 may be more successful on waters of low a lka l in i ty i f the color is not removed by sorption alone. 24 Amberlite IRA-458 has not yet been approved by the United States Pood and Drug A d m i n i s t r a t i o n f o r treatment of foods and beverages. I t can be used, however, i f i t i s fo l l o w e d by a c a t i o n exchange r e s i n . Amberlite IRA-904 Amberlite IRA-904 i s a m a c r o r e t i c u l a r polystyrene s t r o n g l y b a s i c anion exchange r e s i n c o n t a i n i n g quaternary amine a c t i v e groups. I t Is produced i n the bead form with a high degree of c r o s s l i n k i n g of the r e s i n m a t r i x . I t i s very s t a b l e both chemically and p h y s i c a l l y and i s designed to be used as an organic scavenger r e s i n In the c h l o r i d e form. The r e s i n i s regenerated w i t h a 10% NaCl s o l u t i o n and has no pH l i m i t a t i o n s . I t shows extremely high r e s i s t a n c e to organic f o u l i n g due to high p o r o s i t y and a high degree of c r o s s l i n k i n g . The r e s i n has a low i o n exchange c a p a c i t y i n i t s c h l o r i d e form due to i t s high a f f i n i t y f o r that anion. Thus, there i s r e l a t i v e l y l i t t l e change i n the i n f l u e n t water composition a f t e r passage through the scavenger r e s i n . IRA-904 has U. S. Pood and Drug A d m i n i s t r a -t i o n approval and so may be used by i t s e l f f o r removal of organics from municipal water s u p p l i e s . Dowex 11 Dowex 11 anion exchange r e s i n i s a strong base r e s i n w i t h a s p e c i a l styrene divinylbenzene copolymer matrix having a high c a p a c i t y and p o r o s i t y . 25 When used as an organic scavenger the r e s i n i s regenerated wi t h a mixture of 10$ NaCl and 1% NaOH rege n e r a t i o n s o l u t i o n . Dowex 11 i s s a i d to be operable i n the pH range from 0 to 14. In f i e l d t e s t s conducted by Horembala and F e l d t (34), Dowex 11 was used as an organic scavenger r e s i n In f r o n t of other d e i o n i z a t i o n r e s i n beds to remove the organics which were f o u l i n g the beds. The r e s i n was s u c c e s s f u l i n removing the organics r e s p o n s i b l e f o r f o u l i n g the i o n exchange beds, thus extending the le n g t h of the runs and the l i f e of the beds. I t has been suggested that as an organic scavenger, Dowex 11 may r e p l a c e c l a r i f i c a t i o n by sedimentation and f i l t r a t i o n i n the removal of organics i n some water s u p p l i e s c o n t a i n i n g low organic content and low d i s s o l v e d s o l i d s . Granular Darco A c t i v a t e d Carbon The a c t i v a t e d carbon was s u p p l i e d by A t l a s Chemicals and i s made from l i g n i t e c o a l . Grade 12 x 20 1 was used i n t h i s experiment. This a c t i v a t e d carbon has been used to remove co l o r e d organics from water s u p p l i e s i n s e v e r a l commercial i n s t a l l a t i o n s . i N o t e : Grade 12 x 20 r e f e r s to the s i z e of the granular a c t i v a t e d carbon p a r t i c l e s . The granules w i l l pass through a number 12 stieve but w i l l be r e t a i n e d on a number 20. 26 3.3 DEFINITION OF ORGANICALLY BOUND IRON Since the t r i a l and error method has "been chosen, i t i s not considered important to determine whether or not the organically bound iron exists as a complexed compound or as a chelated compound. No attempt has been made to define the chemical nature of the organic-iron complex. Instead i t has been assumed that the iron exists i n an organically bound state i f a l l the following conditions are met. 1. No i r o n i s removed when the solution i s passed through a diatomaceous earth f i l t e r or another kind of f i l t e r which would normally remove Fe(OH)^ c o l l o i d s . 2. No iron Is removed by passing the s o l u t i o n through a manganous greensand f i l t e r . This would normally remove 3+ 2+ Fe- and Fe - ions and Fe(OH)^ by an oxidation and f i l -t r a t i o n process? 3. No iron i s removed by the passage of the solution through a cation exchange r e s i n . This would normally 3+ 2+ remove the Fe and Fe ions. 4. The i r o n must remain dispersed i n the s o l u t i o n f o r several months at a pH between 5 and 8 with no evidence of p r e c i p i t a t i o n of f e r r i c hydroxide. It should be pointed out that Iron could be held i n solution by the organics but s t i l l be removed by manganous greensand or a cation exchange r e s i n . In this case the iron complexation with the organics i s weak and f o r the purpose of th i s report i s not considered to be organically bound. 27 3.4 PREPARATION OP THE ORGANICALLY BOUND IRON SOLUTION The development of a s o l u t i o n which was concentrated and remained r e l a t i v e l y s t a b l e c o n s t i t u t e d a problem. When t e s t i n g r e s i n s , the s o l u t i o n should be f a i r l y concentrated so th a t a mass balance of organic a c i d and i r o n can be e a s i l y c a l c u l a t e d A l s o , i n order to o b t a i n r e l a t i v e l y accurate r e s u l t s using the T o t a l Carbon Analyser, the s o l u t i o n s had to be f a i r l y concentrated. Two s o l u t i o n s were prepared f o r t e s t i n g , one c o n s i s t i n g of a humic and hymatomelanlc a c i d - i r o n complex, the other c o n s i s t i n g of a f u l v i c a c i d - i r o n complex. Since these a c i d s cover the f u l l range of co l o r e d organic a c i d s i n water, i t was considered that the s o l u t i o n s were s u f f i c i e n t f o r t e s t i n g the removal e f f i c i e n c i e s of the various r e s i n s and the a c t i v a t e d carbon chosen. Appendices 1, 2, and 3 e x p l a i n the pr e p a r a t i o n of the two s o l u t i o n s . There were various problems a s s o c i a t e d with the p r e p a r a t i o n , some of which are. .pointed, -out i n the f o l l o w i n g s e c t i o n s and some of which are presented i n the Appendices. 3-5 TEST PREPARATIONS Equipment Required The equipment used i n t h i s experiment was set up according to the Dow Chemical Laboratory Manual on Ion Exchange. One hundred m i l l i t e r b u r r e t t e s were used as i o n exchange columns. 2 8 These b u r r e t t e s were converted to i o n exchange columns by the i n s e r t i o n of a r e s i n bed support i n the bottom of the b u r r e t t e . The support c o n s i s t e d of 4 mm, g l a s s beads under which was placed 1 " of g l a s s wool to support the beads. Separatory funnels were attached to the top of the b u r r e t t e s by the use of a rubber stopper through which the tube from the f u n n e l passed i n t o the top of the b u r r e t t e . Figure 1 shows the apparatus arrangement. The rubber stopper made a t i g h t s e a l so that the f l o w r a t e through the r e s i n could be adjusted by the b u r r e t t e v a l v e a t the bottom. The r e s i n s were placed I n the b u r r e t t e to a depth of approximately 2/3 the height of the b u r r e t t e . Some advantages and disadvantages of usi n g the 1 0 0 ml. b u r r e t t e as a r e s i n column are as f o l l o w s ; Advantages 1. Very simple t o set up. 2. Requires small volumes of r e s i n s and l i q u i d s t o be processed. 3. Complete apparatus i s of convenient s i z e f o r a la b o r a t o r y . Disadvantages 1. L i m i t s maximum r e s i n depth to approximately 2 3 Inches. 2. Small diameter creates a w a l l e f f e c t which may cause s m a l l e r r o r s i n r e s i n volume measurements. 3. B u r r e t t e i s f r a g i l e . 29 Rack Stand Separatory Funnel Rubber Stopper 100 ml Burette Resin k mm Glass Beads Glass Wool Bottle F i g . 1 Resin Column Apparatus G e n e r a l l y speaking, the advantages of us i n g a 1 0 0 ml b u r r e t t e as an i o n exchange column f a r outweigh the disadvan-tages and the equipment and arrangement as i n d i c a t e d worked very w e l l . Tests and Instruments Used T o t a l Carbon Analyzer. A T.O.C. Analyzer (Beckman Model 9 1 5 ) was used to measure the t o t a l organic carbon removed from the s o l u t i o n and the t o t a l organic carbon e l u t e d from the r e s i n s by the var i o u s washes and regeneration s o l u t i o n s . I r o n Analyses .An Atomic Absorption Spectrophotometer ( J a r r e l Ash 82-500) was used to measure i r o n i n the s o l u t i o n , the e f f l u e n t and the regenerated e l u t a n t . Color Analyses Color was measured i n the v i s i b l e range from 3 0 0 nm to 7 0 0 nm using a Bausch and Lomb Spectronic 600,spectrophotometer. Chemical Oxygen Demand The t e s t was performed according to Standard Methods f o r the Examination of Water & Wastewater, 1 3 t h E d i t i o n 1 9 7 1 . .The CO..D. of the s o l u t i o n and e f f l u e n t was used to check the T-^ O.C,, values obtained. 31 Resin P r e p a r a t i o n A f t e r p l a c i n g the r e s i n s In the b u r r e t t e s , they were back-washed to remove a l l a i r bubbles and to a l l o w the r e s i n beads to s e t t l e i n t o a compact u n i t i n which c h a n n e l l i n g e f f e c t s would, be minimized. The r e s i n s were then regenerated i n t o the proper form f o r use as organic scavengers. The r egeneration procedures l a i d out i n the manufacturers' s p e c i f i c a t i o n s were fo l l o w e d . I n a l l cases, a t l e a s t 40 minutes of contact time between the r e s i n and the regenerating s o l u t i o n was allowed. The f l o w r a t e s as o u t l i n e d i n the manufacturers' s p e c i f i c a t i o n s were f o l l o w e d — t h i s was normally 0 . 2 5 to 0.5 g a l / f t ?min. The r e s i n s were then washed wi t h d i s t i l l e d water as the f i n a l preparatory step. I n a d d i t i o n , some of the r e s i n columns were washed as per D u o l i t e Tech Sheet 1 0 5 ( s u p p l i e d by Diamond Shamrock Chemical Co.) to c o n d i t i o n the r e s i n s and remove the s m a ll amounts of s o l u b l e organics on the r e s i n s . This condi-t i o n i n g procedure was as f o l l o w s t A f t e r r e s i n has been placed i n a column, backwashed, s e t t l e d and drained ( l e a v i n g one i n c h of water above the bed) — 1. Plow two bed volumes of 1.5N NaOH through r e s i n (ten minutes). 2. Washout c a u s t i c w i t h f i v e bed volumes of d i s t i l l e d or d e i o n i z e d water ( t h i r t y minutes); d r a i n water from r e s i n l e a v i n g one i n c h above top of bed. 3. Plow two bed volumes of 2N HC1 through the r e s i n (ten minutes). 32 4. Wash out the a c i d w i t h f i v e bed volumes of d i s t i l l e d water ( t h i r t y minutes); d r a i n water from r e s i n to w i t h i n one in c h of top of bed. 5. Repeat the c a u s t i c - r i n s e - a c i d - r i n s e c y c l e o u t l i n e d i n steps 1 - 4 . 6. I f maximum p u r i t y i s necessary, r i n s e the r e s i n w i t h two bed volumes of p o l a r solvent such as acetone or ethanol. I n the p r e s e n t a t i o n of data i n l a t e r chapters any r e s i n noted as "washed" has been washed from steps 1 to 6 using acetone i n the s i x t h step. SECTION 4 HUMIC-IRON REMOVAL FROM AQUEOUS SOLUTION A s o l u t i o n of humic a c i d - i r o n complex was prepared as out-l i n e d i n Appendices 1 and 2. The humic residue used to prepare the s o l u t i o n c o n s i s t e d of: humic a c i d 42$, ether s o l u b l e f a t s and waxes 28%, f u l v i c a c i d 16%, hymatomelanlc a c i d lk%. Since the m a j o r i t y of the co l o r e d organic a c i d s present were humic, the s o l u t i o n i s c a l l e d the humic a c i d s o l u t i o n . 4.1 EXPERIMENT #1 HUMIC-IRON REMOVAL WITH RECOMMENDED REGEN-ERATING SOLUTION. Procedure t The r e s i n columns were prepared according to the i n s t r u c t i o n s i n the Dow Chemical Laboratory Manual on Ion Exchange. The equipment r e q u i r e d and i t s method of pre p a r a t i o n was discussed i n Se c t i o n 3- Before any of the i r o n complex was allowed to pass through the scavenger r e s i n s , they were generated i n t o t h e i r proper form by the use of the f o l l o w i n g s o l u t i o n s . Resin S o l u t i o n Amberlite IRA-904 10$ NaCl i n D i s t i l l e d Water Amberlite IRA-458 10% NaCl i n D i s t i l l e d Water Dowex 11 10$ NaCl and 1% NaOH i n D i s t i l l e d Water. D u o l i t e S-37 k% NaOH i n D i s t i l l e d Water. 3 3 3 4 The f i n a l preparatory step was a d i s t i l l e d water wash. The humic a c i d - i r o n s o l u t i o n was then a p p l i e d to the columns a t a f l o w r a t e which v a r i e d between 0 . 7 5 and 1.0 g a l / f t ^/min. The r e s i n s and a c t i v a t e d carbon used i n t h i s experiment Included i 1. Amberlite IRA-904 2. D u o l i t e S-37 3 . Manganous Greensand 4. Dowex 50W-X8 ( c a t i o n exchange r e s i n ) 5. Dowex 11 6. Amberlite IRA-458 7. A t l a s Chemical A c t i v a t e d Carbon (Granular Darco) Res u l t s t The r e s u l t s of t h i s experiment are presented i n Table I. Very l i t t l e of the i r o n was removed i n passing through the manganous greensand f i l t e r or through the Dowex 50W-X8 c a t i o n exchange r e s i n . A f t e r preparation,the s o l u t i o n was passed through a diatomaceous e a r t h f i l t e r and no removal of i r o n was measured (see Appendix 2). By p e r i o d i c a l l y measuring the i r o n i n the s o l u t i o n over s e v e r a l months, i t was noted t h a t the i r o n remained d i s p e r s e d throughout the s o l u t i o n . Since these c o n d i t i o n s f u l f i l the requirements of o r g a n i c a l l y bound i r o n by the d e f i n i t i o n g i ven i n S e c t i o n 3, the humic a c i d - i r o n s o l u t i o n was considered to be i n the o r g a n i c a l l y bound s t a t e . The number of values averaged to o b t a i n the r e s u l t s shown i n Table I are In d i c a t e d i n Column 7. The accuracy of the i r o n data i s considered to be very good because of the p r e c i s e and accurate nature of the Atomic A b s o r p t i o n Spectrophotometer. In averaging the T.O.C. r e s u l t s , judgement was used to p i c k r e s u l t s 35 Table I Humic-Iron Removal by Resins, A c t i v a t e d Carbon and Manganous Greensand. T.C. mg/l T.I.C. mg/,1 T.O.C. mg/l Fe mg/.l pfl No.of Values averaged T o t a l l-B.V. passed Humic I r o n I n f l u e n t 38 22 16 1 5 . 4 8 .0 IRA 904 Reg. 10% NaCl 14 2 .12 1 3 . 8 6 . a 7 22 IRA 904 washed Reg. 10% NaCl 14.5 1.5 13 1 3 . 6 6 . : i 5 17 D u o l i t e S-37 Reg. 4$ NaOH 34 22 12 1 5 . 0 1 0 . 0 4 14 Manganous Greensand 30 14 16 1 4 . 6 7.5 5 27 Dowex 50W -X8 Reg. HCrl — — — 1 4 . 6 — 5 Dowex 11 Reg. 10% NaCl 1% NaOH 1 9 3 1 6 13.5 9.1 5 16 Dowex .11 Washed Reg. 10% NaCl 1% NaOH 18.5 3.5 1 5 1 4 . 0 9.1 6 18 Darco A c t i v a t e d 3 :1 1 9 12 14.6 8.3 5 13 Carbon IB.V. i n d i c a t e s Bed Volumes of s o l u t i o n passed through the column. 36 which appeared to be most stable and representative. The T.O.C. results must therefore be treated with caution. Generally the data presented in Table I indicates that very l i t t l e of the organics were removed. This is also borne out by the iron data which indicates very l i t t l e removal of iron. It might be noted that the Amberlite resins do remove the total i n -organic carbon or the bicarbonate ions, thus removing the buffering capacity of the water. Upon reviewing the manufacturers' l i terature , this would not have been expected as these resins were in the chloride form. As a general rule the resins in the chloride form were thought to pass bicarbonate ions. The Duolite S-37 resin in the hydroxide cycle did not remove the bicarbonate ions. This was expected as Duolite S-37 in this form is said to achieve organic removal without significant change in the inorganic composition of the water. By comparison of influent to effluent in Nessler tubes, i t was noted that some color was removed in the f i r s t few bed volumes by the IRA-904, the activated carbon, and the Duolite S-37. The amount of color removal varied in that order, with the IRA 9 0 4 resin removing more color than either the activated carbon or the Duolite S-37« In no case, however, was much color removed from the solution. This visual indication of color removal is sub-stantiated by the T.O.C. data which indicated that approximately 4 mg/1 of organic carbon was removed by each of the above three columns. Thus, i t appears that some of the humic acids are removed by Ira 9 0 4 Activated Carbon and Duolite S-37. Comparison of influent to effluent of a l l other resins and 3 7 manganous greensand showed no removal of c o l o r . This was a l s o borne out by the T.O.C. data which i n d i c a t e d t h a t no organic carbon was removed from the s o l u t i o n i n any of the other cases. None of the r e s i n s were e f f e c t i v e i n removing the i r o n present i n the s o l u t i o n . Since t h i s was the primary g o a l , none of these r e s i n s could be considered u s e f u l i n removing the humic a c i d - i r o n complex from water s u p p l i e s . R e s u l t s were not obtained f o r the Amberlite IRA 458 as the pH of the r e s i n was so low tha t the humic a c i d p r e c i p i t a t e d i n the r e s i n column. I t was noted th a t when the humic a c i d was p r e c i p i t a t e d and removed from s o l u t i o n i n the column, so was the i r o n . This was taken as another i n d i c a t i o n t h a t the i r o n was i n f a c t bound to the organic a c i d . Due to these problems wi t h the IRA 458 r e s i n , another experiment was performed, i n which d i f f e r e n t r egeneration techniques were t r i e d . 4.2 EXPERIMENT #2 HUMIC-IRON REMOVAL WITH EXPERIMENTAL REGENE--RATING SOLUTIONS Procedure: The r e s i n columns were prepared and setup using, the same method as i Experiment # 1 . The three r e s i n s used i n t h i s experiment were generated w i t h the f o l l o w i n g s o l u t i o n s : 1. Amberlite IRA 458 X% NaOH and 10% NaCl i n D i s t i l l e d Water. 2. Amberlite IRA 458 10% NaCl i n D i s t i l l e d Water 38 3. Amberlite IRA 9 0 4 1% NaOH and 10% NaCl in D i s t i l l e d Water. 4. Duolite S-37 k% NaOH The IRA 4 5 8 was generated with NaOH and NaCl solution in order to raise the pH of the resin so that the humic acid would not precipitate in the resin column. Another column of IRA 4-58 resin was regenerated in the NaCl form to see i f the precipitation of humic acid would occur again. The IRA 9 0 4 resin was regenerated with the NaOH and NaCl solution to determine the effect of the NaOH on the removal efficiency of the iron complex by the resin. The Duolite S-37 resin was le f t in the same base form as was used i n the previous test. The humic ac id-iron solution was applied to the column at a flow rate which varied between 0.75 and 1.0 gal / f t Vmin. Results t The results of the second experimental run are shown in Table II . Due to problems encountered in determining the Total Inorganic Carbon and Total Organic Carbon on the Total Carbon Analyser, the T . I . C . and T.O.C. data must be treated with caution. In general l i t t l e or no organic carbon was removed by any of the resins. It can be noted again that the Amberlite resins remove the inorganic carbon or bicarbonate ions from the solution. The Duolite S-37 resin appears to have had some organics leached from It , but no increase in color was noted. Very l i t t l e iron was removed by any of the resins. During this run i t was found that the humic acid did not precipitate in the IRA 4-58 resin column which had been regenerated with salt only. No explanation can be given for the discrepancy between IRA 4-58 results in Experiment #1 and Experiment #2. 39 Table II Humic Iron Removal by Experimentally Regenerated Resins. T . C . mg/l T . I . C . mg/l T .O.C. mg/l Pe mg/l pH No. of Values Ave. Total B . V . 1 Passed Original Sample Influent 28-30 17-19 10-12 15.4 7.0 Effluents Prom Resins IRA 458 Reg. 10% NaCl.l^NaOH 12 1 11 13.8 7.8 12 57 IRA 458 Reg. 10% NaCl 11 2 9 13.0 - 13 46 IRA 904 Reg. 10% NaCl,l#NaOH 12 4 8 12.6 6.9 12 54 Duolite S-37 Reg. 4$ NaOH 30.5 16.5 14 13.3 8.7 10 42 1B.V. - indicates Bed Volumes of solution passed through the column. 40 I n c o n c l u s i o n , these r e s i n s cannot be considered s a t i s f a c t o r y f o r the purpose of removing humic a c i d - i r o n complexes from an aqueous s o l u t i o n . S e c t i o n 5 FULVIC-IRON REMOVAL FROM AQUEOUS SOLUTION A dark amber-colored s o l u t i o n of water was obtained from Burns Bog south of Vancouver. Since ho p r e c i p i t a t e was noted when the s o l u t i o n ' s pH was reduced t o 1 i t was concluded that a l l the organic a c i d s present were f u l v i c a c i d s . I r o n was added to t h i s f u l v i c a c i d as described i n Appendix 3. 5.1 EXPERIMENT #1 FULVIC ACID-IRON REMOVAL EFFICIENCY Procedure» The f o l l o w i n g columns were used w i t h the r e s i n s being prepared according to Dow Chemical Laboratory Manual on Ion Exchange: 1. Amberlite IRA 904 2. A t l a s A c t i v a t e d Carbon (Granular Darco) 3. D u o l i t e S-37 4. Manganous Greensand 5. Dowex 11 6. Dowex 50W-X8 (Cation) 7. Amberlite IRA 458 Resin regenerating s o l u t i o n s were: 1. Amberlite IRA 904 \% NaOH and 10$ NaCl i n d i s t i l l e d water. 2. Amberlite IRA.458 1% NaOH and 1 0 # NaCl i n d i s t i l l e d water. 3. Dowex 1 1 1% NaOH and 10% NaCl i n d i s t i l l e d water. 4. D u o l i t e S-37 4# NaOH i n d i s t i l l e d water. 5. Dowex 50W-X8 15$ NaCl i n d i s t i l l e d water. The f u l v i c a c i d - i r o n s o l u t i o n was then passed through the r e s i n s , a c t i v a t e d carbon and manganous greensand a t a f l o w r a t e of 41 42 approximately 1 ga l / f t 3 /min. The T.O. C. was not measured due to problems with the Total Carbon Analyser. Color was measured with the Spectrophotometer. Results i Pig. 2 shows the transmission of l ight vs. wave length as determined by the Spectrophotometer for the effluents from the various columns. It may be clearly seen that Amberlite IRA 904 removed almost a l l of the color present in the solution. The transmission of l ight in this case was very close to that for d i s t i l l e d water. Activated Carbon and Duolite S-37 also removed much of the colored organics from the water. As indicated, a l l other resins and manganous greensand removed very l i t t l e organic color from the solution. Prom Table III i t can be observed that the removal of organic color did not correspond to the removal of iron from the solution. Amberlite IRA 9°4, for instance, is seen to remove almost a l l of the color but very l i t t l e of the iron. The Dowex 5°W-X8 cation exchange resin and the manganous greensand are found to remove most of the iron but very l i t t l e of the colored organics. Thus, i t may be concluded that the iron is not in an organically bound state as previously defined. 4 3 100 80 J D i s t i l l e d Water IRA 904 Trans- — 1 mis- 6 ° sion 40 20 300 -Atlas Activated Carbon Duolite S-37 IRA 458 and Manganous Greensand Dowex 50W-X8 Dowex 11 Fulvic-Iron solution. 400 5 0 0 6 0 0 Wave Length nm 7 0 0 F i g . 2 FULVIC-IRON COLOR REMOVAL BY RESINS, ACT. CARBON AND MANGANOUS GREENSAND. 4 4 Table I I I Ir o n Removal from F u l v i c - I r o n S o l u t i o n E f f l u e n t Bed V o l . Passed No. of Samples Averaged Fe mg/1 pH % Fe Recovered From Column F u l v i c - I r o n I n f l u e n t 1 5 4 IRA 9 0 4 Reg. 1% NaOH, 10% NaCl 32 6 1 2 4 30 A t l a s A c t i v a t e d Carbon 2 2 6 1 8.2 D u o l i t e S-37 Reg. 4 $ NaOH 27 6 0.5 9.9 16 Manganous Greensand 20 5 3.4 6.7 Dowex 1 1 Reg. 1% NaOH 10% NaCl 2 1 4 14 4 16 Dowex 50W-X8 20 5 2 6.2 IRA 4 5 8 Reg. 1% NaOH 10% NaCJL 2 9 5 8 8.2 5 45 A t l a s a c t i v a t e d carbon and D u o l i t e S-37 r e s i n are shown to remove almost a l l the i r o n and much of the organic c o l o r from the s o l u t i o n . Very l i t t l e of the i r o n was regenerated from the D u o l i t e S-37, however. I t was thought that the h y droxyl ions present i n t h i s r e s i n might be p r e c i p i t a t i n g the i r o n as f e r r i c hydroxide w i t h i n the r e s i n matrix and t h a t t h i s p r e c i p i -t a t i o n could cause i r o n f o u l i n g of the r e s i n . I t i s not known i f the a c t i v a t e d carbon could be r e a c t i v a t e d when the i r o n was present. Dowex 1 1 and Amberlite IRA 4 5 8 are seen to pass the i r o n , w ith the Dowex 1 1 having e s s e n t i a l l y no e f f e c t on the i r o n c o n c e n t r a t i o n , w h i l e Amberlite IRA 4 5 8 passed about one h a l f of the i r o n . A combination of r e s i n s and manganous greensand or a c t i v a t e d carbon could be used to remove both c o l o r and i r o n from the f u l v i c a c i d - i r o n s o l u t i o n i f the s o l u t i o n were t o remain un-changed. The s o l u t i o n c h a r a c t e r i s t i c s changed w i t h storage time, however, and the c o l o r e d organics and i r o n become I n c r e a s i n g l y d i f f i c u l t to remove as the s o l u t i o n aged. The e f f e c t s of t h i s change are shown i n F i g u r e J. As the s o l u t i o n changes, the percent t r a n s m i s s i o n of l i g h t decreased (Figure 3 ) • i n d i c a t i n g an increase of c o l o r . The increased c o l o r was a l s o noted v i s u a l l y and the s o l u t i o n was seen to darken considerably. As i n d i c a t e d i n Figure 4, the Amberlite IRA 9 0 4 r e s i n e f f e c t i v e l y removed a l l the c o l o r from the f u l v i c a c i d - i r o n s o l u t i o n i n i t i a l l y . A f t e r the o r i g i n a l s o l u t i o n had aged f o r three weeks, however, the r e s i n removed much l e s s c o l o r 46 300 400 500 600 700 Wave Length nm F i g . 3 COLOR CHANGE AS FULVIC-IRON SOLUTION AGES 47 lOOt 8CH. Trans-60 mis-sion 40 20\ Dis t i l l ed Water ^Ini t ia l Fulvic-Iron Effluent <-—Initial Fulvic-Iron Influent Aged Fulvic-Iron Effluent 300 400 500 600 700 Wave Length nm F i g . 4 COLOR PASSED BY IRA 904 RESIN AS FULVIC-IRON AGES 48 from the s o l u t i o n . F i g u r e 4 a l s o shows the d i f f e r e n c e i n c o l o r "between the i n i t i a l f u l v i c a c i d - i r o n s o l u t i o n and the e f f l u e n t from the r e s i n a f t e r the f u l v i c a c i d - i r o n s o l u t i o n had been aged. This c o l o r d i f f e r e n c e was observed to be r e l a t i v e l y s m a l l . I t should be s t a t e d here that the r e s i n s were completely regenerated before the three-week-old f u l v l c a c i d - i r o n s o l u t i o n was passed through them. In order to be sure t h a t i t was the a d d i t i o n of i r o n t o the f u l v i c s o l u t i o n that was causing t h i s change i n c h a r a c t e r i s -t i c s , a s o l u t i o n of j u s t f u l v i c a c i d which was 1 ^ months o l d was passed through the IRA 904 r e s i n . These r e s u l t s are presented i n Figure 5 and i t may be seen t h a t the removal of c o l o r Is the same as the removal obtained passing the i n i t i a l f u l v i c a c i d - i r o n s o l u t i o n through the r e s i n . This r e s u l t i n d i c a t e s t h a t the i r o n i s i n f a c t changing the c h a r a c t e r i s t i c s of the organic s o l u t i o n . I t i s thought t h a t the i r o n becomes more s t r o n g l y bound to the organics as the s o l u t i o n ages. I n the n a t u r a l environment the s t r e n g t h of these o r g a n i c - i r o n bonds may be strong or weak depending on the c o n d i t i o n s present. The removal c h a r a c t e r i s t i c s of both weakly and s t r o n g l y bound o r g a n i c - i r o n are important from a water p u r i f i c a t i o n standpoint; thus i t was decided to tr a c e these removal c h a r a c t e r i s t i c s as the f u l v i c i r o n s o l u t i o n ages. I 1 1 1 1 300 400 500 600 700 Wave Length nm Pig. 5 AGED FULVIC ACID AND IRA 904 EFFLUENT COLOR. 50 I t was p r e v i o u s l y noted th a t the D u o l i t e S-37 removed the i r o n from s o l u t i o n and that t h i s i r o n c ould not be e l u t e d ; thus, i r o n f o u l i n g i s i n d i c a t e d i n t h i s r e s i n . Therefore, the D u o l i t e S-37 r e s i n was not considered s a t i s f a c t o r y f o r t r a c i n g the f u l v i c a c i d - I r o n removal c h a r a c t e r i s t i c s over the per i o d of time. Dowex 11 was p r e v i o u s l y seen to pass most of the i r o n and remove l i t t l e of the co l o r e d organic a c i d s , so I t could not be considered s a t i s f a c t o r y f o r the experiment. Amberlite 458 was u n s a t i s f a c t o r y as i t removed very l i t t l e c o l o r and any i r o n removed could not be e l u t e d from the r e s i n . Amberlite IRA 904 was t h e r e f o r e chosen f o r the experiment as i t removed a l l the co l o r e d organics and allowed most of the i r o n to pass through. Of the i r o n which was removed by the r e s i n , 30% could be e l u t e d , thus reducing the r i s k of i r o n f o u l i n g . S e c t i o n 5 .2 describes the experiments which were undertaken to develop the best regeneration c y c l e f o r t h i s r e s i n . 5.2 EXPERIMENT #2 REGENERATION CYCLE SUITABLE FOR FULVIC-IRON REMOVAL. Procedure» Due to the f i n d i n g s presented i n the previous experiment, i t was decided to use IRA 904 and a c a t i o n exchange r e s i n i n s e r i e s to remove both c o l o r and i r o n from the f r e s h f u l v i c a c i d -i r o n s o l u t i o n . The c a t i o n exchange r e s i n chosen was Dowex MSC-1, as i t was understood t h a t t h i s r e s i n could be economi-c a l l y used to p u r i f y water s u p p l i e s and was r e s i s t a n t to organic f o u l i n g . 51 This experiment was intended to determine the most e f f i c i e n t regenerating c y c l e s f o r the combination of the IRA 904 and Dowex MSC-1. I t was decided to t r y three types of regeneration processes. , Method 1. The IRA 904 and Dowex MSC-1 were both regener-ated w i t h NaCl. I t was thought t h a t i f both r e s i n s could be regenerated w i t h the same s o l u t i o n i t would minimize the operati n g costs of the process. Method 2. The IRA 904 was regenerated w i t h 10$ NaCl and 1% NaOH s o l u t i o n , and the Dowex MSC-1 by NaCl. I t was hoped th a t the NaCl might f i r s t be used t o regenerate the Dowex r e s i n and then used i n conjunction w i t h the NaOH t o regenerate the IRA 904 r e s i n . Method 3 . The IRA 904 r e g e n e r a t i o n c y c l e c o n s i s t e d of an HCL wash f i r s t to remove the i r o n and some of the organics. Then a 1% NaOH and 10$ NaCl s o l u t i o n would be used t o regenerate the r e s i n and remove the r e s t of the organics. F i n a l l y , an HCL wash was used to remove a l l the hydroxyl ions present so t h a t f e r r i c hydroxide could not form i n the r e s i n . I n t h i s case, the Dowex r e s i n was regenerated by HS1. The equipment used was the same as described i n S e c t i o n 3 . The regeneration procedure was as per the manufacturers' s p e c i f i c a t i o n s and Secti o n ' 3> A f i n a l d i s t i l l e d water r i n s e was used i n a l l three methods. 52 Results > The results of the three regeneration methods are shown in Table IV. The f i r s t regeneration process posed a problem when the NaCl regenerating solution would only remove a small portion (approximately 3^%) of the organic carbon present in the IRA 904 resin. The iron removed by the NaCl regeneration solution was also rather limited (approximately 51%)• Therefore, this method of regeneration was considered unacceptable. The regenerating solution used in Method 2 is seen to work very well in eluting the organics from the IRA 904 res in. The total recovery of organic carbon is 110$, as seen in Table IV. The iron removal achieved by this method is not very great, however, with only (25%) of the iron being recovered. Iron fouling problems would l ike ly develop i f this method of regeneration were used. It is thought that the hydroxyl ions present on the resin exchange sites precipitate the iron causing f err i c hydroxide to form within the resin matrix. It was concluded that method 2 should not be used to regenerate the res in. The regeneration efficiencies using Method 3 were very good, with 9k% of the iron and 91$ of the T.O.C. being eluted from the resins. As both the IRA 904 and the Dowex MSC-1 were placed in the same column, the iron and T.O.C. recoveries are only shown under the IRA 904 column in Table IV. It w i l l be noted that the great majority of the iron was removed by the HC1 wash at the beginning of the regeneration cycle. Due to the superior performance of the resins when regenerated by Method 3, i t was concluded that this should be the regeneration 53 TABLE IV F u l v i c - I r o n E l u t i o n E f f i c i e n c y Methods 1st IRA 904 Dowex MSC T o t a l T o t a l Fe T o t a l Wash 2nd Wash -1 1st Rec. or T.O.C. Recovery mg mg Wash mg mg Removed % mg From S o l . Method 1 NaCl NaCl Fe Recovered 4.2 28.2 32.4 56.6 57% T.O.C. Recovered 100 100 291 34^ Method 2 NaOH NaCl NaCl Fe Recovered 9.5 6.1 15.6 63.0 25% T.O.C. Recovered 338 338 308 110# Method 3 HC1 NaOH NaCl Dowex MSC-Fe 1 i n same Recovered 34.2 1.6 column as 35.8 38 9^% IRA 904 T.O.C. Recovered 105 70 175 193 91% 54 method used to t r a c e the changing organic a c i d - i r o n s o l u t i o n . The f u l v i c - i r o n removal e f f i c i e n c y of the IRA 904 and Dowex MSC-1 r e s i n s i n s e r i e s i s presented i n Table V. I t can be seen th a t the i r o n removal Is e x c e l l e n t ? even a f t e r 88 bed volumes, the Iron removal e f f i c i e n c y i s 93% > T.O.C. removal i s a l s o very good, as the removal e f f i c i e n c y i s 82% a f t e r 88 bed volumes of s o l u t i o n have passed through the r e s i n . C o lor was measured by the tr a n s m i s s i o n of l i g h t a t a wave-le n g t h of 350 :nk. The c o l o r of the f i n a l e f f l u e n t was much l e s s than that of the feed s o l u t i o n . I t i s thought that t h i s c o n s t i t u t e s a s a t i s f a c t o r y removal e f f i c i e n c y , c o n s i d e r i n g the co n c e n t r a t i o n of organics and Iron i n the o r i g i n a l s o l u t i o n . 55 Table V F u l v i c - I r o n Removal E f f i c i e n c y Bed V o l . T.O.C. mg/l #T.0.C. Removed Fe %Fe Trans. mg/l Removed L i g h t @350.nm F u l v i c - I r o n I n f l u e n t 83 15 4 Method 1 0-33 33-61 4 9 95 89 0 0 . 2 5 98 85 65 Method 2 0-31 31-56 4 10 95 88 0 . 2 5 0.5 98 97 85 62 Method 3 0-18 18-42 42 - 7 0 70-88 3 9 11.6 15 96 89 86 82 0.25 0.5 1.0 1.0 98 97 93 93 89 72 49 42 SECTION 6 FULVIC-IRON SOLUTION CHANGE WITH AGE 6 . 1 EXPERIMENT DESCRIPTION An experiment was designed to measure and observe the changes which time produced i n a f u l v i c a c i d - i r o n s o l u t i o n . The experimental r e s u l t s were gathered over a 33 day p e r i o d . Amberlite IRA 904 r e s i n was used to determine how much of the organic a c i d - i r o n complex could be removed by an organic scavenger r e s i n as the time allowed f o r organo-iron complex-a t i o n Increased from 6 to 33 days. Dowex 50W-X8 was used to determine how much i r o n could be removed by a c a t i o n exchange r e s i n as the time allowed f o r complexation increased to 33 days. In order to r e l a t e changes i n the f u l v i c - i r o n s o l u t i o n to the o r i g i n a l s o l u t i o n , the same f u l v i c a c i d s o l u t i o n without any i r o n added was used as a c o n t r o l s o l u t i o n throughout the experiment. I t was assumed tha t t h i s s o l u t i o n would not change i t s chemical c h a r a c t e r i s t i c s . This assumption was based upon past experimentation i n which a s i m i l a r s o l u t i o n from Burns Bog d i d not change s i g n i f i c a n t l y i n a two month p e r i o d . At the end of 33 days, the f u l v i c - i r o n s o l u t i o n was passed through a column of A t l a s a c t i v a t e d carbon t o determine how much of the f u l v i c a c i d - i r o n complex could be removed by t h i s process. The f u l v i c a c i d - i r o n s o l u t i o n was a l s o passed through a manganous greensand eolumn to determine what amount of i r o n would be removed. 56 57 F i n a l l y , both the f u l v i c a c i d - i r o n s o l u t i o n and the f u l v i c a c i d s o l u t i o n were subjected to the organic a c i d f r a c t i o n a t i o n t e s t a t i n t e r v a l s throughout the month to determine i f e i t h e r s o l u t i o n was changing to a humic-hymatomelanic a c i d s o l u t i o n . 6.2 EXPERIMENTAL PROCEDURE. A s o l u t i o n of f u l v i c a c i d obtained from Burns Bog was s p l i t i n h a l f , w i t h one f r a c t i o n being used t o prepare a f u l v i c a c i d - i r o n s o l u t i o n as per Appendix 3. At f i r s t the c o l o r i n both s o l u t i o n s was the same. This was not s u r p r i s i n g as past experimentation had i n d i c a t e d t h a t i n i t i a l l y very l i t t l e of the added i r o n i s s t r o n g l y complexed to the f u l v i c a c i d and the f u l v l c a c i d - i r o n s o l u t i o n i s very s i m i l a r to the f u l v i c a c i d s o l u t i o n i n pH, T.O.C. and c o l o r . Four Amberlite IRA 904 and one Dowex 50W-X8 r e s i n columns were prepared. These p a r t i c u l a r r e s i n s were chosen because of good previous performance. The Dowex 50W-X8 was regenerated w i t h a s o l u t i o n of 2N HC1 . Two of the Amberlite IRA 904 r e s i n columns were regenerated as per method 3 i n the previous s e c t i o n . The other two were regenerated i n the same manner except t h a t the f i n a l a c i d wash was de l e t e d . This was done i n order to determine i f the f i n a l a c i d wash was a c t u a l l y r e q u i r e d . The f u l v i c a c i d - i r o n s o l u t i o n was passed through the 58 Dowex r e s i n and through one of each type of IRA 9 0 4 column. The c o n t r o l s o l u t i o n of f u l v i c a c i d was passed through the remaining two IRA 904 columns. For c l a r i f i c a t i o n purposes the f o l l o w i n g numbers have been assigned to the r e s p e c t i v e r e s i n columns: Resin Column Resin Used Feed S o l u t i o n Regeneration Procedure #1 IRA 904 F u l v i c A c i d Method 3 #2 IRA 904 F u l v i c A c i d Method 3 d e l e t i n g f i n a l a c i d wash. #3 IRA 904 F u l v i c I r o n Ac i d -Method 3 #4 IRA 904 F u l v i c I r o n Ac i d - Method 3 d e l e t i n g f i n a l a c i d wash. Dowex 5 0 W -X8 F u l v i c I r o n Ac i d - HOI E f f l u e n t t e s t i n g was c a r r i e d out 6 , 10, 15 and 33 days a f t e r sample p r e p a r a t i o n . On each t e s t date ten bed volumes of f u l v i c a c i d c o n t r o l s o l u t i o n were passed through r e s i n columns number 1 and 2. S i m i l a r l y ten bed volumes of f u l v i c a c i d -i r o n s o l u t i o n were passed through r e s i n columns numbers 3 and 4 and the Dowex 50W-X8 r e s i n column. The Dowex r e s i n was used to determine how much of the i r o n was a c t u a l l y o r g a n i c a l l y bound on any of the t e s t i n g dates (as per the d e f i n i t i o n i n S e c t i o n 3 ) . On day 3 3 , the f u l v i c a c i d - i r o n 59 solution was passed through a column of manganous greensand to check the results from the Dowex resin and to complete the test for organically bound iron. The fu lv ic acid control solution and the fulv ic acid-iron solution were also passed through columns of activated carbon (Atlas Granular Darco) on day 3 3 , to determine the removal of each by the activated carbon. A l l of the former solutions and the effluents were tested for iron, C .O.D. , T . O . C , pH and the transmission of ultraviolet and v i s ib le l ight . The resins were regenerated twice during the test period. In addition to the above tests, the organic acid fract ion-ation test was carried out on each of the testing dates. The pH of both the fulv ic acid- control solution and the fu lv ic acid-iron solution was lowered to pH=l. Observations were made as to how much precipitate was formed. This precipitate would normally be c lass i f ied as humic or hymatomelanic acid by definit ion i f found in a natural water supply. 6 . 3 EXPERIMENTAL RESULTS Fulvic Acid Removal by Resins Both #1 and #2 resin columns removed the fu lv ic acid effectively from the solution. Figures 6 and 7 show the percent transmission of ul traviolet and v i s ib le l ight through the fulv ic acid solution and the effluent from the resins. In a visual 6o D i s t i l l e d Water Wave Length nm P i g . 6 FULVIC EFFLUENT COLOR FROM RESIN #1 Note: F o r a c t u a l c o l o r s on Day 33 See F i g . 8 61 300 400 500 600 700 Wave Length nm Pig . 7 FULVIC EFFLUENT COLOR FROM RESIN # 2 Notei For actual colors on Day 33 See F i g . 8 62 i n s p e c t i o n of t h e e f f l u e n t s , no d i f f e r e n c e c o u l d be n o t e d between d i s t i l l e d w a t e r and t h e e f f l u e n t s of t h e s e r e s i n s . F i g u r e 8 i s a pho t o g r a p h o f t h e e f f l u e n t s on day 33 and shows t h a t b o t h r e s i n s t o t a l l y removed t h e o r g a n i c c o l o r f r om t h e f u l v i c a c i d s o l u t i o n . T a b l e V I shows t h e T.O.C, C.O.D., and pH of t h e f u l v i c a c i d c o n t r o l s o l u t i o n on t h e f o u r t e s t i n g d a t e s . I t can be n o t e d t h a t t h e s o l u t i o n s t a y s r e l a t i v e l y c o n s t a n t w i t h r e g a r d t o the c h a r a c t e r i s t i c s g i v e n and f r o m F i g u r e s 6 and 7 i t can be n o t e d t h a t t h e c o l o r of t h e f u l v i c a c i d s o l u t i o n does n o t change w i t h t i m e . As i n d i c a t e d i n T a b l e V I I , t h e T.O.C. r e m a i n i n g i n s o l u t i o n a f t e r p a s s i n g t h r o u g h R e s i n #1 i s v e r y low. T h i s s u p p o r t s t h e r e s u l t s o b t a i n e d f r o m t h e l i g h t s c a n shown i n F i g u r e 6. I t may a l s o be obs e r v e d t h a t t h e pH o f t h e e f f l u e n t i s v e r y s i m i l a r t o t h e pH of t h e f u l v i c a c i d c o n t r o l s o l u t i o n . T h i s shows t h a t t h e a c i d wash removed e s s e n t i a l l y a l l t h e h y d r o x y l i o n s p r e s e n t i n t h e r e s i n a f t e r r e g e n e r a t i o n w i t h NaCl and NaOH. T a b l e V I I I shows the c h a r a c t e r i s t i c s of t h e e f f l u e n t from R e s i n #2. The T.O.C. v a l u e s a r e v e r y l ow and i n k e e p i n g w i t h t h e r e s u l t s from t h e l i g h t s c a n p r e s e n t e d i n F i g u r e 7. I t w i l l be n o t e d t h a t the day 15 sample has a much h i g h e r T.O.C. t h a n t h e o t h e r s . I t i s thought t h a t t h e r e s i n was n o t r i n s e d w e l l enough' f o l l o w i n g t he r e g e n e r a t i o n c y c l e and t h a t t h i s caused i t t o pass some o r g a n i c s i t would o t h e r w i s e have removed. Most of the c o l o r was removed, even though a T.O.C. c o n t e n t o f 8 mg/l remained. The pH of the e f f l u e n t f r om R e s i n # 2 i s 63 F i g u r e 8 FULVIC EFFLUENT AND FULVIC-IRON EFFLUENT ON DAY 33 Top Row, L e f t t o Right» P u l v i c A c i d , #2 R e s i n E f f l u e n t , #1 R e s i n E f f l u e n t and A c t i v a t e d Carbon E f f l u e n t . Bottom Row, L e f t to Rig h t : F u l v i c - I r o n , #4 R e s i n E f f l u e n t , #3 R e s i n E f f l u e n t and A c t i v a t e d Carbon E f f l u e n t . 6 4 Table VI F u l v i c A c i d Feed S o l u t i o n . Day 6 mg/1 Day 10 mg/1 Day 15 mg/1 Day 33 mg/1 T.O.C. 41 - 42 40 C.O.D. 105 - 100 90 pH 3 - 9 3 . 9 4 . 0 3 . 9 Table V I I R e sin #1 F u l v i c E f f l u e n t s Day 6 mg/1 Day 10 mg/1 Day 15 mg/1 Day 23 mg/1 T.O.C. 0 2 2 1 C.O.D. - - - 0 Fe 0 0 0 0 pH 4 . 1 3-8 4.2 3 . 9 10 B.V. of s o l u t i o n were used In a l l cases. Table V I I I Resin #2 F u l v i c E f f l u e n t s Day 6 mg/1 Day 10 mg/1 Day 15 mg/1 Day 33 mg/1 T.O.C. 0 1 8 2 C.O.D. - 16 5 Fe mm - - -pH 6.2 4 . 5 7 . 0 4 . 9 10 B.V. of s o l u t i o n were used i n a l l cases. 65 seen t o be higher than the pH of the feed s o l u t i o n . This In d i c a t e s the presence of hydroxyl ions i n the r e s i n . The pH of the e f f l u e n t i s seen to decrease from 6.2 to 4.5 as more bed volumes of s o l u t i o n are passed through the r e s i n . (The r e s i n was regenerated on day 12). This was expected to happen as the r e s i n w i l l tend t o give up the hydroxiKyl ions f i r s t before g i v i n g up the c h l o r i d e i o n s . In c o n c l u s i o n , the f u l v i c a c i d c o n t r o l s o l u t i o n remained q u i t e constant i n i t s c h a r a c t e r i s t i c s and the two IRA 904 r e s i n columns continued to remove the organic a c i d e f f e c t i v e l y throughout the experiment. F u l v i c A c i d - I r o n Removal by Resins Both #3 and #4 r e s i n columns removed c o l o r and T.O.C. q u i t e e f f e c t i v e l y on days 6 and 10. By day 1 5 , however, the s o l u t i o n had changed to such an extent that very l i t t l e organic c o l o r or T.O.C. removal was t a k i n g place, as mayube observed i n F i gures 9 and 10. The photographs ( F i g . 8 and 12) show; the c o l o r of the e f f l u e n t s on day 33. From Table IX i t can be noted t h a t the T.O.C. and C.O.D. decrease as the s o l u t i o n ages. The pH of the s o l u t i o n was adjusted to 4.5 on day 13 and then to 6.0 on day 1? because i t was found that the f u l v i c - I r o n complex p r e c i p i t a t e d a t lower pH values. This phenomenon i s d iscussed i n d e t a i l on page 82. Since the pH of the s o l u t i o n i n the l a t t e r part of the experiment was more conducive to m i c r o b i a l a c t i v i t y , i t i s thought t h a t such a c t i v i t y r e s u l t e d i n the decrease of T.O.C. and C.O.D. 66 100 , 80 Trans-60 mis-sion 40 20 D i s t i l l e d Water 300 400 500 600 Wave Length nm 700 Pig. 9 FULVIC-IRON EFFLUENT COLOR FROM RESIN #3 67 100 T D i s t i l l e d Water % Trans-mis-s i o n 400 500 600 Wave Length nm F i g . 10 FULVIC-IRON EFFLUENT COLOR FROM RESIN #4 700 68 Table IX Fulvic-Iron Feed Solution. Day 6 mg/l Day 10 mg/l Day 15 mg/l Day 33 mg/l T .O.C . 4 1 - 38 35 C.O.D. 103 - 85 76 Fe 1 4 . 5 15 1 4 1 4 pH 3 . 8 3 . 8 4 . 5 5 . 8 Table X Resin #3 Fulvic-Iron Effluents. Day 6 mg/l Day 10 mg/l Day 15 mg/l Day 33 mg/l T . O . C . C.O.D. Fe pH 0 12 4.3 1 2 . 7 5 3.9 17 66 6.75 5-3 16 43 1 0 . 0 5.4 6'9 The values i n Table X. f o r the e f f l u e n t from Resin 3 confirm the l i g h t scan shown i n F i g u r e 9 . The T.O.C. i n the e f f l u e n t i s very low on days 6 and 1 0 . However, on days 15 and 3 3 . the T.O.C. jumps to much higher values (approximately 5 0 $ of the con c e n t r a t i o n i n the i n f l u e n t f u l v i c a c i d - i r o n s o l u t i o n ^ The pH values of the e f f l u e n t are not s i g n i f i c a n t l y changed from those of the i n f l u e n t . This i s as expected, s i n c e no hydroxyl ions should be present i n t h i s r e s i n . The i r o n data i n d i c a t e s that l e s s i r o n i s passed through the r e s i n on days 15 and 33 than on days 6 and 1 0 . The data shown i n Table X I f o r the e f f l u e n t from Resin k confirm the l i g h t scan data presented i n F i g u r e 1 0 . Only the day 6 T.O.C. value does not agree w i t h the c o l o r i n d i -c a t i o n i n the l i g h t scan; however, si n c e the water was s t i l l r e l a t i v e l y f r e e of c o l o r (as observed v i s u a l l y ) , the d i s -agreement was not considered too important. G e n e r a l l y , the T.O.C. and C.O.D. values of the e f f l u e n t are very low f o r days 6 and 1 0 . On day 15 and 3 3 , however, these values Increased a great d e a l . This i s r e f l e c t e d i n the change of c o l o r of the e f f l u e n t as i n d i c a t e d i n F i g u r e 1 0 . I t may be noted i n Table XI t h a t the presence of hydroxyl Ions In the r e s i n i s r e f l e c t e d i n the pH of the e f f l u e n t , which i s higher than the pH of the i n f l o w i n g f u l v i c a c i d - i r o n s o l u t i o n . 70 Table XI Resin #4 Fulvic-Iron Effluents. Day 6 Day 10 Day 15 Day 33 mg/1 mg/1 mg/1 mg/1 T.O.C. 1 2 21 17 C.O.D. 4 59 -Fe 7 . 5 12 . 7 5 8 . 5 10 . 0 PH 4.8 4 . 1 7 . 2 6 . 2 Table XII Fulvic--Iron Effluent from Dowex 50W-X8 & Manganous Greensand ( Dowex 50W-X8 ) mg/1 mg/1 mg/1 mg/1 Day 6 Day 10 Day 15 Day 33 Fulvlc Iron Manganous Feed Solution Greensand Day 33 Day 33 T.O.C. 29 - 32 30 35 31 C.O.D. 104 - 76 Fe 1 .0 1 .5 8 . 5 10 . 0 14 12 . 7 5 PH 3 . 0 3 . 0 3 . 1 3-1 5,8 6 . 1 71 Table XII shows the amount of iron passed by the Dowex 50W-X8 on a l l four testing dates. It may be noted that the Dowex cation resin removes much less iron on days 15 and 33 than on days 6 and 10. This data is taken to indicate that the iron is becoming more bound to the organics as the solution ages. On day 33» very l i t t l e iron was removed from the solution by manganous greensand. This was further confirmed by the data on Figure 11. Thus the iron may be said to be in the organically bound state from our definit ion presented in Section 3 . A photograph of the Dowex 50W-X8 and manganous greensand effluents is shown in Figure 12. In conclusion, i t appears that as the fu lv i c - i ron solution ages, the iron-organic bonds become stronger and the IRA 904 resins begin to pass much more color, T . O . C . , and C.O.D. . Thus while IRA 904 w i l l remove fulv ic acid from water i t w i l l not effectively remove the fu lv ic acid- iron from water. Iron Elution Efficiency for Resins #3 and #4 As may be seen from Table XIII regeneration by method 3 was effective as long as the iron was not strongly bound to the fulv ic acid. 72 D i s t i l l e d Water I 300 400 500 600 700 Wave Length nm P i g . 11 FULVIC-IRON EFFLUENT COLOR BY DOWEX 50W-X8 & MANGANOUS GREENSAND. 73 F i g . 1 2 FULVIC-IRON EFFLUENT COLOR CN DAY 33  Top, L e f t to Right* 1. F u l v i c A c i d - I r o n S o l u t i o n . 2 . E f f l u e n t from Manganese Greensand. 3 . A c t i v a t e d Carbon E f f l u e n t . Bottom, L e f t to Rights 1 . E f f l u e n t from #3 IRA 9 0 4 R e s i n . 2 . E f f l u e n t from #4 IRA 9 0 4 R e s i n . 3 . Dowex 5 0 W-X8 E f f l u e n t . 7 4 Table XIII Percent Iron Eluted from Resins #3 and #4 . Regeneration Method $Fe Eluted $ Pe Eluted on Day 13 on Day 34 Resin #3 Method 3 1 0 0 $ 55% Resin #4 Method 3 with f ina l acid wash deleted 7 4 $ 69% Notes Regeneration "by Method 3 requires an HC1 wash followed "by regeneration solution of 10$ NaCl and 1% NaOH followed by another HC1 wash. When the Iron became more strongly bound to the fulv ic acid only 55$ of the iron could be removed from the resin by Method 3 . Regeneration by method 3 with f i n a l ac'Id wash deleted was less effective when the iron was weakly bound but more effective when the fulv ic acid iron bonds became stronger. As the fu lv ic - i ron becomes more strongly bound regeneration becomes more d i f f i c u l t and neither method could be considered acceptable as 31 to 45$ of the iron remains in the resin. Fulvic and Fulvic-Iron Removal by Activated Carbon On day 3 3 • the fu lv ic acid control solution and the fu lv ic acid- iron solution were passed through columns of Darco activated carbon. Table XIV shows that the activated carbon removed almost a l l the T.O.C. and C.O.D. from the fu lv ic acid control solution. 75 This is confirmed by the l ight scan in Figure 13 and the photo-graph (Figure 8 ) , which shows that very l i t t l e color is l e f t in solution. It is evident from the data in Table XIV that the a c t i -vated carbon removes much less of the T.O.C. or C.O.D. from the fulv ic acid-iron solution. This is also indicated in the l ight scan shown in Figure 14. The photographs (Fig. 8 and 12) show that the fu lv ic iron effluent is quite highly colored. Thus i t is concluded that activated carbon w i l l remove almost a l l T .O.C. and color from an aged fulv ic acid solution, but removes much less T.O.C. and color from an aged fu lv i c - i ron solution. Table XIV Activated Carbon Effluents  T.O.C. C.O.D. Fe mg/l mg/l mg/l pH Fulvic Acid Feed 40 90 0 3 . 9 Activated Carbon Fulvic Acid 3 9 0 ? . Fulvic-Iron Feed 35 76 14 5-8 Activated Carbon Fulvic-Iron 15 2 8 Notei A l l values taken on day 33. 76 300 5oo 500 6~00 700 Wave Length nm Pig . 13 FULVIC COLOR REMOVAL BY ACTIVATED CARBON 77 D i s t i l l e d Water Wave Length nm P i g . 1 4 FULVIC-IRON EFFLUENT COLOR BY ACTIVATED CARBON 78 F u l v i c A c i d - I r o n Color Increase The c o l o r of the f u l v i c a c i d s o l u t i o n and the f u l v i c a c i d - i r o n s o l u t i o n on day 1 were the same (Nessler tubes were used f o r comparison). As the f u l v i c a c i d - i r o n s o l u t i o n aged, the c o l o r was observed to deepen whereas the c o l o r of the f u l v i c a c i d s o l u t i o n remained the same. Figu r e 15 shows the c o l o r of the s o l u t i o n s on day 33- As may be seen, the c o l o r has d r a s t i c a l l y Increased. F u l v i c A c i d Change to Humic A c i d I n the presence of Iro n The d e f i n i t i o n of f u l v i c a c i d i s that i t remains i n s o l u t i o n at a pH of 1, while humic and hymatomelanlc a c i d s p r e c i p i t a t e a t a pH of 1 to 2. For the purposes of s i m p l i -f i c a t i o n , a l l organic a c i d s which p r e c i p i t a t e below a pH=2 w i l l be c a l l e d humic a c i d s i n t h i s r e p o r t . The o r i g i n a l s o l u t i o n of f u l v i c a c i d from Burns Bog would remain i n s o l u t i o n at pH=l or lower. Table XV shows the r e s u l t s of the organic a c i d f r a c t i o n a t i o n t e s t on the f u l v i c a c i d c o n t r o l s o l u t i o n and on the f u l v i c a c i d - i r o n s o l u t i o n f o r the various t e s t i n g days. As can be seen, the f u l v i c a c i d c o n t r o l s o l u t i o n does not change; i t remains, throughout the experiment (by d e f i n i t i o n ) t o t a l l y f u l v i c a c i d . This i s not the case w i t h the f u l v i c a c i d - i r o n s o l u t i o n . I t only remains f u l v i c a c i d u n t i l j u s t a f t e r the 1 0 t h day. As has been p r e v i o u s l y shown, the i r o n appears to become t i g h t l y bound wit h the f u l v i c a c i d between day 10 and 15, and , once t h i s occurs, the whole complex 79 Pig. 1 5 COLOR OF FULVIC AND FULVIC-IRON SOLUTION (Day 33) Lefts Fulvic Acid Control Solution. Rights Fulvic Acid-Iron Solution. 80 Table XV Organic A c i d F r a c t i o n a t i o n Day 6 Day 10 Day 15 Day 33 F u l v i c pH=l No P r e c i p . No P r e c i p . No P r e c i p . No P r e c i p . A c i d S o l u t i o n pH=1.5 pH=2 F u l v i c - pH=l Ir o n S o l u t i o n Very s l i g h t Very Brown s l i g h t P r e c i p . Brown Pre c i p , Brown Brown Organic Organic P r e c i p i t a t e P r e c i p i t a t e pH=1.5 No P r e c i p . No P r e c i p . Dense Dense Brown Brown Organic Organic P r e c i p i t a t e P r e c i p i t a t e pH=2 81 # # €| O C ^ F i g u r e 16 PRECIPITATED FULVIC-IRON AFTER 33 DAYS AGING Top Row, L e f t to Rights P r e c i p i t a t e d F u l v i c A c i d - I r o n pH=2 1.5 and 1. Bottom Row, L e f t to Rights F u l v i c A c i d pK=2, 1.5 and 1. 82 acts as a humic a c i d , p r e c i p i t a t i n g as a dense brown organic p r e c i p i t a t e a t pH=2. I t w i l l , however, go back i n t o s o l u t i o n at higher pH values. Figure 16 i s a photograph of the p r e c i -p i t a t e d f u l v i c - i r o n on day 33 • This phenomenon was observed i n the carboy of f u l v i c a c i d - i r o n feed s o l u t i o n i t s e l f . On day 1 3 , most of the organics i n the s o l u t i o n were found t o have p r e c i p i t a t e d , l e a v i n g a s l i g h t l y c o l o r e d supernatant w i t h a pH of 3 - 6. This supernatant was found t o have a T.O.C. = 9 mg/1 and an i r o n content = 6 . 7 5 mg/1. Since the f u l v i c a c i d - i r o n solutton had a T.O.C. = 40 mg/1 and an i r o n content of 15 mg/1 a few days before, i t was assumed t h a t the p r e c i p i t a t e d organics amounted to 31 mg/1 and the p r e c i p i t a t e d i r o n amounted to 8 . 2 5 mg/1. I t i s thought t h a t the 8 . 2 5 mg/1 of i r o n could be considered to be o r g a n i c a l l y bound to the 31 mg/1 of organic a c i d . A f t e r some experimentation i t was decided to r a i s e the pH of the s o l u t i o n to 4 . 7 because the organic a c i d and i r o n went back i n t o s o l u -t i o n a t t h i s pH. I t Is i n t e r e s t i n g to note that on day 15 the Dowex c a t i o n exchange r e s i n passed 8 . 5 mg/1 of Iron. The amount of o r g a n i c a l l y bound i r o n i n the s o l u t i o n on day 13 was c a l c u l a t e d (above) a t 8 . 2 5 mg/1. Since the Dowex c a t i o n exchange r e s i n passes only o r g a n i c a l l y bound I r o n , t h i s was taken as f u r t h e r proof that the i r o n was b i n d i n g w i t h the f u l v i c a c i d to form an i r o n organic complex. 83 No f u r t h e r p r e c i p i t a t i n g problems were encountered a f t e r r a i s i n g the pH of t h i s s o l u t i o n . I t was noted on days 15 and 17 however, that the pH of the s o l u t i o n was decreasing, so on day 17 i t was decided to adj u s t the s o l u t i o n to pH= 6.0. The i r o n and the c o l o r remained dispersed i n the s o l u t i o n f o r the next l i months without any n o t i c e a b l e p r e c i p i t a t i o n . Undoubtedly there are many chemical p o s s i b i l i t i e s by which the i r o n might cause the f u l v i c a c i d to r e a c t l i k e humic a c i d and to pass through the IRA 904 r e s i n s and a c t i v a t e d carbon w h i l e the f u l v i c a c i d by i t s e l f would not. As s t a t e d p r e v i o u s l y , no attempt has been made to examine the chemical s t r u c t u r e of the f u l v i c a c i d - i r o n complex. SECTION 7 SUMMARY & RESULTS Organically bound iron has posed problems in municipal water supplies for many years. An effort has been made in this study to solve the problem of i ts removal from these water supplies. After reviewing the l i terature the t r i a l and error approach to solving the problem seemed most suitable. Newly developed ion exchange resins and activated carbon appear to present a good solution to the problem, especially when dealing with very small communities and single dwellings. The l i terature review revealed that the resins commonly used in North America to treat water supplies are produced by three manufacturers: 1 . Dow Chemical Co. Ltd. (Alchem Ltd. in Canada) 2. Diamond Shamrock Chemical Co. 3 . Rohm and Haas These companies were contacted and asked to supply resins which they ^thought would be most l ike ly to remove organically bound iron from water. The resins received were: 1 . Duolite S - 37 from Diamond Shamrock 2. Amberlite IRA 904 and IRA 458 from Rohm and Haas 3 . Dowex 11 from Alchem Ltd. A l l of these resins have been used to remove organics and color from water supplies in commercial instal lat ions . 84 85 Atlas Chemicals were contacted and a sample of Granular Darco Activated Carbon made from l igni te coal was received from them. This particular type of activated cafcbon has been used in several instal lations to remove color ed-organics from water supplies. Two solutions of organically bound iron were used in the experiments: 1. Humic and hymatomelanic acids which were extracted from composted leaves formed the major portion of the organic acids present in the f i r s t solution. 2. Water from Burn's Bog containing only fu lv ic acids was used in the second solution. The ferrous iron was added to each solution under controlled conditions. Experimentation revealed the following observations and results 1. It was found that iron-organic interactions in solution were time dependent. 2. The reactions between humic acid and iron were quick as . 95% of the iron became strongly bound to the humic acid within four hours. 3. Fulvic acid- iron reactions were much slower and a period of 15 days was required for 57% of the iron to become strongly bound-to the fu lv id acid. 4 . A fu lv ic acid- iron solution in which the iron is strongly bound to the fulv ic acid, behaves in much the same manner as a humic acid- iron solution. After 13 days of aging the fulv ic acid-iron complex precipitated at a pH of 4 . 7 but went back into solution when the pH was raised above this value. 86 Amberlite IRA 904 and D u o l i t e S-37 and A t l a s Darco a c t i v a t e d carbon were a l l e f f e c t i v e (approximately 100$) i n removing f u l v i c a c i d from s o l u t i o n as evidenced by the low c o l o r and T.O.C. values In the e f f l u e n t . Amberlite IRA 904, D u o l i t e S-37 and A t l a s Darco a c t i v a t e d carbon were not e f f e c t i v e i n removing f u l v i c a c i d - I r o n or humic a c i d - i r o n from s o l u t i o n as evidenced by the high c o l o r and T.O.C. values i n the e f f l u e n t . ^ - • . (Amberlite IRA 904 and A t l a s Darco A c t i v a t e d carbon removed approx-imate l y 55% of the T.O.C. and approximately 35% of the i r o n from the f u l v i c a c i d i r o n s o l u t i o n which had aged f o r 33 days. Amberlite IRA 904, D u o l i t e S-37 and A t l a s Darco A c t i v a t e d Carbon removed approximately 25% of the T.O.C. and % of the i r o n from the humic a c i d i r o n solution},. Dowex 50W-X8, Dowex MSC-1, and manganous greensand were e f f e c t i v e i n removing i r o n which was not o r g a n i c a l l y bound to the f u l v i c or humic a c i d i n the s o l u t i o n . O r g a n i c a l l y bound i r o n could not be removed by these r e s i n s nor would they remove any f u l v i c a c i d or humic a c i d from the s o l u t i o n . IRA 458 d i d not remove f u l v i c - i r o n or humic-iron from s o l u t i o n . Dowex 11 would not remove f u l v i c - i r o n or humic-iron from s o l u t i o n . F u l v i c a c i d Is e f f e c t i v e l y e l u t e d from Amberlite IRA 904 by a regenerating s o l u t i o n of 10$ NaCl and 1% NaOH. 11. Fulvic acid is effectively eluted from Duolite S-37 by a regenerating solution of 4$ NaOH. 12. Iron fouling can occur i f Amberlite IRA 904 or Duolite S-37 are le f t in the hydroxyl fcrm as the iron which is not strongly bound to the organic acids precipitates in the resin column. If Amberlite IRA 904 is acid washed immediately before and after use this problem is minimized. 13. Some of the strongly bound organic iron was removed by the Amberlite IRA 904 resin (approximately 3 5 $ ) . This organic-iron could not be effectively removed with an acid wash or with the 10$ NaCl and 1$ NaOH solution ( 3 0 -45$ of the iron remained in the res in) . This indicates that iron fouling might occur in the res in. 14. The color of the fu lv i c - i ron solution became considerably darker as the solution aged and the iron became more strongly bound to the fulv ic acid. SECTION 8 CONCLUSIONS It is concluded that: " ' - Neither the activated carbon (Atlas Darco) nor the organic scavenger resins (Amberlite IRA 904, Amberlite IRA 4-58, Duolite S-37, Dowex 11) w i l l successfully remove aged fulv lc acid-iron complexes or humic acid- iron complexes from water. -Activated carbon (Atlas Darco) and the organic scavenger resins (Amberlite IRA 904, Duolite S-37) w i l l successfully remove fu lv ic acid from water which has no iron present. -Manganous greensand and the cation exchange resins (Dowex MSC-1, Dowex 50W-X8) w i l l successfully remove iron from water which has no organic acids present. - Activated Carbon (Atlas Darco) or a combination of Amberlite IRA 904 and Dowex MSC-1 resins w i l l successfully remove both fulv ic acid and iron from solution i f the fu lv ic acid is not fu l ly complexed to the iron. However, the fulv ic acid- iron reactions are time dependent, therefore each situation would need to be examined independently and could vary throughout the year. It is not expected that any combination of resins or activated carbon would be successful in removing the fu lv ic acid and iron a l l of the time. - Fulvic acid-iron which has had sufficient time to become fu l l y complexed has the same precipitation characteristics as humic acid- iron complexes. Both organic-iron complexes w i l l precipitate at a low pH (2 to 4 . 7 ) but w i l l stay in solution when the pH is greater than 6. 8 8 89 BIBLIOGRAPHY 1. Clark, PranciSjM., Robert M. Scott and Ester Bone, "Heterotrophic Iron Precipitating Bacteria", Journal AWWA, August, 1967. 2. Black, A. P. and R. P. Christman, "Chemical Characteristics of Pulvic Acids", Journal AWWA, July 1963. 3. Starkey, Robert L . , "Transformations of Iron by Bacteria", Journal AWWA, October 1945. 4 . Shapiro, J . , "Chemical and Biological Studies on the Yellow Organic Acids of Lake Water", Limnol Oceanog., 2 : l 6 l (1957) 5. Oldham, W. and E. F . Gloyna, "Interactions of Iron with So i l Organic Acids", Journal AWWA, November 1969• 6. Singley, J . E . , R. H. Harris and J . S. Maulding "Correction of Color Measurements to Standard Conditions", Journal AWWA, A p r i l , 1966. 7. Christman, R. P. and M. Ghassemi, "Chemical Nature of Organic Color in Water", Journal AWWA, June 1966. 8. Burges, A. "The Nature and Distribution of Humic Acid", S c i . Proc. Roy Dublin S o c , Ser. A, 1:53 ( I 9 6 0 ) . 9. Burges, N. A . , H. M. Hurst, and B. Walkden, "The Phenolic Constituents of Humic Acid", Geochim. et Cosmochim. Acta, 28:1547 ( 1 9 6 4 ) . 10. Jakab, T . , P. Dubach, N. C. Mehta and H. Devel, "Degradation of Humic Substances, III Degradation with A l k a l i " , Z. Pflanz-enernaehr. Dveng. Bodenk. (Ger.) 102:17 (1963). 11. Wilson. A. L . , "Determination of Fulvic Acids in Water", Journ. Appl. Chem. 9:501 (1959). 12. Black, A. P. and R. F . Christman, "Characteristics of Colored Surface Waters" Journal AWWA, June 1963. 13. Babcock, R. H . , "Iron and Manganese in Water Supplies and Methods of Removal", Water and Sewage Works, 9 8 : 4 4 2 (1951). 1 4 . Ghosh, M. M. , "A Study of the Rate of Oxidation of Iron in Aerated Ground Waters", Dept. of C i v i l Engineering, University of I l l ino i s (1962.) 90 15. H a l l , K . , "Natural Organics Matter in the Aquatic Environ-ment", Doctoral Dissertation, University of Wisconsin,1970. 16. Shapiro, J . , "Yellow-Acid-Cation Complexes in Lake Water, Science, 127«702 (1958). 17. Christman, C . H . , "Ultramicroscopic Studies of Colloids in Water", Journ. AWWA, 21:1076 (August, 1 9 2 9 ) . 18. Wiley, B. F . and H. Jenning, "Iron and Manganese Removal with Potassium Permanganate", Journ. AWWA, June, 1963« 19. Welch, W. A . , "Potassium Permanganate in Water Treatment", Journ. AWWA, June, 1963. 2 0 . Fr i sch , N.W. and R. Kunin, "Organic Fouling of Anion Exchange Resins", Journ. AWWA, July, I960. 21. Abrams, I . M . , "Scavenger Resins for Removal of Organics from Water", presented at the International Water Conference of the Engineers' Society of Western Pennsy-lvania, Sept. 3 0 , 1964. 22. Abrams, I.M. and R.P.Bres l in , "Present Studies on the Removal of Organics from Water", presented at the 26th Annual Meeting, International Water Conference of the Engineers* Society of Western Pennsylvania, Pittsburgh, Pa. , Oct. 22, 1965. 23. Jayes, D.A. and I.M.Abrams, "Color Removal from a New England River Water!':, International Water Conference, Engineers' Society of Western Pennsylvania, Nov. 7, 1966. 24. Singley, J . E . , Chairman, A.W.W.A. Research Committee on Coagulation and Research Committee on Color Problems, "Coagulation and Color Problems", Journ. AWWA, May, 1970 (Joint Report). 25. Hale, F . E . , "The relat ion between Aluminum Sulfate and Color in Mechanical F i l t ra t ion" , Journ. Ind. and Eng. Chem., 6:632 (1914). 26. Hedgepeth, L . L . , N.C. Olsen, and W. C. Olsen, "Chlorinated Copper as a New Coagulant", Journ. AWWA. 20:167 (1928). 27. Maulding, J . S . and R.H. Harris , "Effect of Ionic Environment and Temperature on the Coagulation of Color Causing Organic Compounds with Ferric Sulfate", Journ. AWWA, A p r i l , 1968. 28. H a l l , E . S. and R.F . Packham, "Coagulation of Organic Color with Hydrolyzing Coagulants", Journ. AWWA, 57:1149 Sept. 1965. ?1 29. V i l a r e t , M.R., Do c t o r a l D i s s e r t a t i o n , U n i v e r s i t y of F l o r i d a 1966. 30. Abrams, I.M., "Removal of Organics from Water by Synt h e t i c Resinous Adsorbents", Chemical Engineering Progress. V o l . 65, No. 97, 1969. 31. Mucke, D. and R. Obenaus, Wiss. Z. Univ. Rostock, 12:103 (1963). 32. Data Sheet and Laboratory Tests f o r Amberlite as c a r r i e d out by Rohm and Haas Company. 33. D r l s c o l l , M.t Unpublished data from t e s t s performed f o r the Rohm and Haas Company, Southwest Medical I n s t i t u t e , D a l l a s , Texas. 34. Horembala, L. E. and C. A. F e l d t , "Ion Exchange Screen f o r Organic Matter Improves Demineralizer Performance". Presented a t the 28th meeting of I n t e r n a t i o n a l Water Conference of the Engineers' S o c i e t y of Western Pennsylvania, P i t t s b u r g h , Pennsylvania, D e c , 1967. 35. Bohnsack, G., "Tests on the Behaviour of Anion Exchangers Toward Humic A c i d s " , M i t t e l l u n g e n der VGB. 76: 53-8 (1963). 36. Hager, D.G. and M.E. F l e n t z e , "Removal of Organic Contaminants by Granular Carbon F i l t r a t i o n " , Journ. AWWA, 1440, Nov. 1965. 37. O'Donovan. D. C , "Treatment w i t h Ozone", Journ. AWWA, II67, (September), 1965. 38. Coogan, G.J., "Diatomite F i l t r a t i o n f o r Removal of Ir o n and Manganese", Journ. AWWA, 1507, D e c , 1962. 39. Faust and Hunter. Organic Compounds i n Aquatic Environments. Marcel Dekker, 1971 40. Mattson and Mark. A c t i v a t e d Carbon-Surface Chemistry and  Adso r p t i o n from S o l u t i o n . Marcel Dekker, 1971 41. Rawson and F u l l e r , Manual of B r i t i s h Water Engineering. PP. 538-539. 42. Campbell, R. M., "The Use of Ozone i n the Treatment of Loch Turret Water", Journ. I n s t . Water Engrs., 17:333 (1963). 4 3 . Ghassemi, M. and R.F. Christman, " P r o p e r t i e s of the Yellow Organic Acids of N a t u r a l Waters", Limnology and Oceano-graphy, V o l . 13, No. 4, Oct. 1968. 92 Menzel, D. w. and Vaccaro, R. P., "The Measurement of Dissolved Organic and Particulate Carbon in Seawater", Limnol. and Oceanography, 9» (1964). APPENDIX 1 PREPARATION OP HUMIC AND HYMATOMELANIC ACIDS These acid s were e x t r a c t e d from leaves which had been composting f o r two years. The method of e x t r a c t i o n i n v o l v e d soaking the composted l e a f m a t e r i a l i n d i s t i l l e d water which had i t s pH r a i s e d to approximately 11 by the a d d i t i o n of NHjjOH. The composted m a t e r i a l was soaked f o r eighteen hours. This mixture was then f i l t e r e d and the r e s u l t i n g l i q u i d a c i d i f i e d w i t h HC1 t o a pH of approximately 2. Any pre-c i p i t a t e was f i l t e r e d and d r i e d f o r two hours a t 70°C. This dark brown p r e c i p i t a t e d m a t e r i a l was then s t o r e d i n a d e s s i c a t o r . In order to determine what percentage of the above m a t e r i a l was a c t u a l l y humic and hymatomelanlc a c i d , t h e m a t e r i a l was f r a c t i o n a t e d as per Figu r e 17 and the f o l l o w i n g formula used. T o t a l residue weight=weight of ether s o l u b l e f a t s and waxes + weight of humic a c i d + weight of hymatomelanlc a c i d + weight of f u l v i c a c i d . The dark brown residue was weighed and d i s s o l v e d i n d i s t i l l e d water which had i t s pH adjusted to 9 wit h NH^OH. This concentrate was then washed w i t h d i e t h y l ether i n a sep-a r a t i n g f u n n e l to remove the ether s o l u b l e f a t s and waxes. The weight of the ether s o l u b l e f a t s and waxes was determined by evaporating the ether and weighing the r e s i d u e . 93 9.4 Concentrate ( D i e t h y l Ether, Washed) S o l i d Precipitate E t h y l A l c o h o l L i q u i d ( F u l v i c Acid) F r a c t i o n 1 S o l u b l e (Hymatomelanic Acid) F r a c t i o n III I n s o l u b l e (Humic Acid) F r a c t i o n I I F i g . 17 SCHEMATIC DIAGRAM OF FRACTIONATION PROCEDURE. The pH of the remaining s o l u t i o n was then adjusted to pH=l by the a d d i t i o n of HC1, and the concentrate was f i l t e r e d . The r e sidue f i l t e r e d from t h i s s o l u t i o n was d r i e d and weighed to determine the t o t a l weight of the humic and hymatomelanic a c i d s . This residue was then washed wi t h e t h y l a l c o h o l and r e f i l t e r e d . The f i l t e r e d r esidue was d r i e d and weighed to determine the amount of humic a c i d present i n the concentrate. The weight of the f u l v i c a c i d present was determined by the p r e v i o u s l y given formula. The percentages of the t o t a l f o r the d i f f e r e n t a c i d f r a c t i o n s i n the concentrate were found t o be: Ether s o l u b l e f a t s and waxes = 28$ F u l v i c A c i d = 16% Humic A c i d = 42$ Hymatomelanic A c i d = 14$ T o t a l Residue wt. =100$ Since the humic a c i d makes up the g r e a t e s t s i n g l e p o r t i o n of t h i s s o l u t i o n , the s o l u t i o n i s r e f e r r e d to as the humic a c i d s o l u t i o n . APPENDIX 2 THE COMPLEXATION OP HUMIC ACID TO IRON IRON SALT USED Several experiments were performed to determine by what method the iron should be added and what iron sal t should be used. FeSO^, P e C l 2 and Fe(NH£j,)2(S0ij,)2 were t r i ed in these experiments. The procedure consisted of purging a flask of d i s t i l l e d water with nitrogen for approximately one hour in order to remove a l l dissolved oxygen. The ferrous salt was then added to this d i s t i l l e d water and dissolved under a nitrogen purge to ensure that no dissolved oxygen would oxidize the ferrous iron to f e r r i c iron. The pH of this solution was adjusted to between 8 to 9 . Several solutions of each of the above ferrous salts were prepared in concentrations varying from 2 mg/l to 5 0 mg/l. These solutions were allowed to s i t overnight exposed to a i r . It was found that the solutions containing Fe(NH^)2(S0j[j,)2 had the best developed precipitate in the morning. A l l the solutions formed a precipitate which could be f i l t ered . As a further check Pe(NHij,) 2(S0^) 2 was added by the same procedure as above to a water which contained an a lka l in i ty of 200 mg/l. 96 97 The samples were allowed to s i t exposed to a i r overnight and i n the morning they were c e n t r i f u g e d f o r 25 minutes a t 2200 rpm to remove the p r e c i p i t a t e . The supernatants of a l l the samples were found to c o n t a i n no i r o n . I t was concluded t h a t the f e r r o u s i o n would come out of s o l u t i o n forming F e ( 0 H ) 2 or Pe(0H )3 as a f i l t e r a b l e p r e c i p i t a t e a t any c o n c e n t r a t i o n above 2 mg/1 I f exposed to a i r overnight a t a pH of between 6 and 8 . Problems were encountered when a combination of a l k a l i n i t y , hardness and i r o n were added to the humic a c i d s o l u t i o n . A f t e r s e v e r a l experiments i t was decided to add only I r o n and a l k a l i n i t y to the humic a c i d s o l u t i o n as when calcium hardness was added i t tended to p a r t i a l l y p r e c i p i t a t e the humic a c i d and a very poor s e t t l i n g floe was formed. PREPARATION OF THE HUMIC ACID-IRON SOLUTION A s o l u t i o n of humic a c i d was prepared by d i s s o l v i n g 40 mg/1 of d r i e d humic acid,prepared as per Appendix 1, i n d i s t i l l e d water of pH=9. A l k a l i n i t y (200 mg/1 measured as CaC03> was added to t h i s s o l u t i o n i n the form of Na HCO^. This adjusted the pH of the s o l u t i o n to 8 . 3 . The s o l u t i o n was then purged w i t h n i t r o g e n f o r approximately 2 hours to remove a l l the d i s s o l v e d oxygen. A f e r r o u s I r o n s o l u t i o n of Fe(NH/j,)2 ( S 0 ^ ) 2 was prepared under n i t r o g e n purge as p r e v i o u s l y explained. A f t e r approximately two hours the 98 i r o n s o l u t i o n was withdrawn by a p i p e t t e and t r a n s f e r r e d to the humic a c i d s o l u t i o n t a k i n g care that none of the i r o n s o l u t i o n came i n contact w i t h a i r . The humic a c i d i r o n s o l u t i o n was l e f t under a n i t r o g e n purge f o r the next three hours In order to assure t h a t the fe r r o u s i r o n would l i n k to the humic a c i d . Previous experiments had determined tha t t h i s was the best procedure to:,use. A f t e r the i r o n and humic a c i d had been together under n i t r o g e n purge f o r three hours, the n i t r o g e n was shut o f f and the s o l u t i o n was aerated f o r 30 minutes. I t was thought th a t any uncomplexed f e r r o u s Iron would be o x i d i z e d to f e r r i c i r o n and would p r e c i p i t a t e as FeCOH)^ I f high d i s s o l v e d oxygen l e v e l s were maintained. No p r e c i p i t a t e was n o t i c e d In the s o l u t i o n nor was any n o t i c e d when the s o l u t i o n wasiipassed through a number 4 l Watman f i l t e r . A sample of the s o l u t i o n was a l s o passed through a diatomaceous earth f i l t e r w i t h no removal of i r o n . I t was th e r e f o r e concluded th a t no f e r r i c hydroxide had p r e c i p i t a t e d a f t e r being aerated. Problems occurred w i t h t h i s s o l u t i o n changing with time. However, the i r o n c o n c e n t r a t i o n of the s o l u t i o n remained r e l a t i v e l y s t a b l e and the i r o n remained dispersed throughout the s o l u t i o n f o r s e v e r a l months. The T.I.C. and T.O.C. were seen to change as the s o l u t i o n got o l d e r . Both were found to decrease i n c o n c e n t r a t i o n though the s o l u t i o n d i d not v i s i b l y change c o l o r . The T.O.C. was thought to decrease due to 99 bacterial action while the T . I . C . was thought to decrease due to the acidic nature of the organic acids. It was noted in several cases that as the organic acid- iron solution got older the pH of that solution decreased. Since the iron became complexed to the humic acid by the def init ion in Section 3 very quickly and remained complexed for several months this solution was considered to be quite good for testing purposes. APPENDIX 3 COMPLEXATION OP FULVIC ACID TO IRON Highly colored water was obtained from Burns Bog ( a peat bog area near the Fraser River south of Vancouver, B. C ) . When tested by lowering the pH to 1 i t was found that this water contained only fu lv ic acids. This solution was purged with nitrogen for. four hours and a ferrous ammonium sulfate solution was added by the same procedure outlined in Appendix 2 . The nitrogen purge was continued for another three hours to allow the organic acid time to l ink with the iron. The solution was then aerated for two hours to ensure a high dissolved oxygen content. Since the pH of the natural bog water was 4 , i t was not expected that the f err ic hydroxide would form and precipitate out immediately. After a few days, the solution was passed through a diatomaceous earth f i l t e r with no removal of iron. Through experimentation with this solution i t was found that i t did not i n i t i a l l y meet the definit ion of organically bound iron used in this research. The reaction between the iron and the organic acid was time dependent and the solution changed in color and characteristics as i t became older. At no time, however, did the iron ever precipitate as f err ic hydroxide and under the correct pH conditions i t was found to remain dispersed throughout the solution for months. The details of this changing solution are given in Chapter 6. 100 

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