UC-NRLF QD /JO ; SB 35 (L (* MANGAN ;R SUPPLIES BY HARRY PEACH CORSON B. S. New Hampshire College, 1910 M. S. University of Illinois, 1912 THESIS Jf Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY IN CHEMISTRY IN THE GRADUATE SCHOOL OF THE UNIVERSITY OF ILLINOIS 1915 EXCHANGE MANGANESE IN WATER SUPPLIES BY HARRY PEACH CORSON \\ B. S. New Hampshire College, 1910 M. S. University of Illinois, 1912 THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY IN CHEMISTRY /w- THE GRADUATE SCHOOL OF THE UNIVERSITY OF ILLINOIS 1915 ACKNOWLEDGMENT This investigation was carried out under the direction of Dr. Edward Bartow, professor of sanitary chemistry in the University of Illinois and Director of the Illinois State Water Survey. The writer wishes to express his gratitude to Professor Bartow for the helpful suggestions received and the kindly interest shown during the progress of the work. CONTENTS Page. Acknowledgment 2 Introduction 5 Determination of manganese in water 5 Previous investigations 5 Experimental studies 7 Preparation of solutions 7 The lead-peroxide method 9 The sodium-bismuthate method 15 The persulphate method 19 Comparison of three colorimetrie methods 23 Eelative value of colorimetrie methods 24 Manganese in water supplies 25 General occurrence 25 Methods of analysis 28 Manganese 28 Iron 29 Dissolved solids 29 Manganese in waters of Illinois 29 Wells in Potsdam sandstone 29 Wells in St. Peter sandstone 29 Wells in limestone 31 Wells in unconsolidated deposits 31 Springs 35 Coal-mine drainage 36 Elvers and lakes 37 Summary 38 Eemoval of manganese from water supplies 39 Methods 39 Manganese permutit 44 Sand filtration 48 Manganese-removal plants in Illinois 54 Eemoval of manganese at Anna 54 Eemoval of manganese at Mount Vernon 60 Incrustation of water pipes by manganese-bearing waters 62 Conclusion 64 Vita . . 66 3605 ILLUSTRATIONS Page.' Figure 1. Map of Illinois showing occurrence of manganese in water from wells in unconsolidated deposits 34 2. Experimental sand filters for the removal of manganese 48 MANGANESE IN WATER SUPPLIES By H. P. Corson. INTRODUCTION Water supplies containing manganese have been considered un- common in the United States, and determinations of manganese are made in but few laboratories as a part of the general routine work of water analysis. Even in the selection of a water supply for a com- munity the content of manganese is seldom considered. In April, 1911, the attention of the Illinois State Water Survey was called to a serious incrustation which had formed in the city water system of Mount Vernon, Illinois. 1 An analysis showed that this incrustation contained 4.4 to 8.8 per cent and that the original water contained 0.6 part per million of manganese. Manganese was found later, in a number of other water supplies both public and private, of the State. Manganese in a water supply is objectionable because it deposits in water pipes a dark incrustation, which in some pipes is so extensive as to cause complete stoppage. It stains plumbing fixtures a dark color due to the separation of the dioxide. It also stains fabrics yellow or brown when water containing it is used in the laundry. In these respects waters containing manganese resemble those which contain iron, but the deposits are darker and more difficult to remove than those produced by waters which contain iron. The present investiga- tion was undertaken on account of the economic importance of this subject. The problem has been studied from the standpoints of the quantitative determination of manganese, its occurrence and distribu- tion in natural waters, and its removal from water supplies. DETERMINATION OF MANGANESE IN WATER Previous Investigations Theoretically, it might seem that any accurate method for the determination of manganese in substances could be successfully ap- plied to the determination of the element in water. Many methods are, however, wholly impracticable. Manganese occurs in water in relatively small amounts, usually only a small fraction of a milligram 1 Corson, H. P., Occurrence of manganese in the water supply and in an incrustation in the water mains at Mount Vernon, Illinois: Illinois Univ. Bull., Water-Survey Series 10, 57-65 (1913). 5 *'s "* w i 6 .MANGANESE IN WATER SUPPLIES per liter. In some waters several milligrams per liter are found, but those in which more than 10 milligrams per liter of the element are encountered are very uncommon. Most other salts are present in nat- ural waters in amounts many times as great as the salts of manganese. These conditions eliminate some of the accurate standard gravimetric and volumetric methods for the determination of manganese. If they are used, under most conditions, large volumes of water must be evap- orated in order to procure a sufficient quantity of the element for de- termination. In complete analysis of the mineral content of water samples these procedures may not be seriously objectionable, but in rapid work, such as the analytical control of a manganese-removal plant, they would be wholly impracticable. Several water analysts have recommended volumetric or gravi- metric methods for manganese. Liihrig and Becker 1 report satisfactory results in applying Knorre 's 2 persulphate peroxide method to the determination of man- ganese in water. If the water contains less than 10 milligrams per liter of manganese, however, they state that it must be con- centrated by evaporation. Klut 3 also recommends the same method for waters whose content of manganese is more than 10 milligrams per liter. He states, however, that 5 to 10 liters of the sample should be used. Prescher 4 recommends that the manganese be precipitated with potassium chlorate from a one-liter sample as manganese dioxide after concentration with nitric acid. The precipitated manganese dioxide is then dissolved in standard oxalic acid, the excess of which is determined by titrating with potassium permanganate. He states that the amount of manganese found must be increased by 10 per cent in order to give a correct value. Noll 5 precipitates the manga- nese as the dioxide in an ammoniacal solution with bromine water. This precipitate is then treated with hydrochloric acid and potassium iodide, and the liberated iodine is titrated with sodium thiosulphate. Results which were in good agreement with the theoretical values were obtained on some artificially prepared manganese waters. The volume of sample used was 500 cubic centimeters. All these methods, how- ever, have found little favor and colorimetric methods are in general use. Colorimetric methods for the determination of manganese de- J Luhrig, fl., and Becker, W., Zur Bestimmung des Mangans im Trinkwasser : Pharm. Zentralhalle, 48, 137-42 (1907). fKnorre, G. von, Ueber eine neue Methode zur Manganbestimmung : Z. angew. Chem., 14, 1149-62 (1901). 8 Klut, H., Nachweis und Bestimmung von Mangan im Trinkwasser: Mitt. kgl. Pru- fungsamt. Wassersorg. Abwasserbeseit., 12, 182-94 (1909). *Prescher, Johannes, Zur Bestimmung des Mangans im Trinkwasser: Pharm. Zentral- halle, 47, 799-802 (1906). *Noll, H., Manganbestimmung in Trinkwasser : Z. angew. Chem., 20, 490-2 (1907). PREPARATION OF SOLUTIONS 7 pend on oxidation of the manganous salt to permanganate and com- parison of the color produced thereby with standards of known con- tent of permanganate. Three oxidizing agents, lead peroxide (Pb0 2 ), sodium bismuthate (NaBi0 3 ), and ammonium persulphate ((NH 4 ) 2 S 2 8 ) have been used for the oxidation. The committee on standard methods of water analysis 1 permits use of the bismuthate and the lead-peroxide methods for the determi- nation of amounts of manganese less than 10 milligrams per liter but recommends Knorre's 2 volumetric persulphate method if more than that amount is present. In the Bureau of Chemistry, U. S. Department of Ag- riculture 3 , the colorimetric persulphate method is used. It was found on inquiry, that no water chemists use the lead-peroxide method. As several methods are used for determining manganese in water and some literature has accumulated concerning their accuracy and sources of error it seemed advisable to make a careful comparison of them for the proposed revision of the report of the committee on standard methods of water analysis. 4 Accordingly the lead-peroxide method, the sodium-bismuthate method, and the ammonium-persul- phate method were carefully compared. Experimental Studies PREPARATION OF SOLUTIONS Solutions of manganous chloride, potassium permanganate, and manganous sulphate, of known content of manganese were prepared. Manganous chloride. A standard solution of manganous chlo- ride was prepared by dissolving approximately 32 grams of pure manganous chloride (MnCl 2 .4H 2 0) in a liter of distilled water. To obtain pure manganous chloride a solution of about 200 grams of Baker's Analyzed manganous chloride in one liter of distilled water was boiled with a small amount of manganese carbonate prepared by adding sodium carbonate to a portion of the original solution, filter- ing, and washing the precipitate. Possible traces of iron, aluminium, and chromium were thus removed. The mixture was then filtered, after which the filtrate was treated with ammonium sulphide to re- move copper, lead, and other heavy metals. The solution was then acidified with hydrochloric acid and boiled to remove hydrogen sul- *Standard methods for the examination of water and sewage, Am. Pub. Health Assoc., New York, 2nd ed., 49-51 (1912). ^norre, G. von, Ueber eine neue Methode zur Manganbestimmung : Z. angew. Chem., 14. 1149-62 (1901). 3 Colorimetric determination of manganese: in Proc. 28th Ann. conv Assoc Off Agr. Chemists, U. S. Agri. Dept., Bur. Chem. Bull. 162, 78-79 (1912). 4 To be published in 1916. MANGANESE IN WATER SUPPLIES phide, after which it was filtered. A small amount of copper, which was present, was thus removed. An excess of sodium carbonate was next added, and the manganous carbonate was separated by filtration and washed free from chlorides. Most of this precipitate was then dissolved in hydrochloric acid. A small portion of that which did not dissolve was added to the solution, and the mixture was boiled and filtered. Crystalline manganous chloride was obtained on evapora- tion. The chloride in the standard solution of this was determined gravimetrically, and the amount of manganese was calculated from that result. Manganese was also directly determined by evaporating to dryness a 50 cubic centimeter portion of the solution with sulphuric acid, heating, and weighing as manganous sulphate. Gooch and Austin 1 have shown that this method is accurate. The average of triplicate determinations by each method gave the following results: By determining chlorine as silver chloride one cubic centimeter contains 1.604 milligrams of chlorine and 1.245 milligrams of man- ganese. By determining manganese as manganous sulphate one cubic centimeter contains 1.254 milligrams of manganese. The mean of these two values, 1.250 milligrams of manganese, was taken as the strength of the solution, which was then diluted to one-tenth of its original strength, so that one cubic centimeter con- tained 0.125 milligram of manganese. Potassium permanganate. For the preparation of standards of permanganate by simple dilution a standard solution was prepared by dissolving in one liter of water 0.2880 gram of Kahlbaum's potas- sium permanganate that had been crystallized twice from double dis- tilled water and dried over sulphuric acid. The content of one cubic centimeter of this solution was, therefore, assumed to be 0.100 milli- gram of manganese. Manganous sulphate. Dilute solutions of permanganate are not very stable. 2 In order to check their value and to have standards prepared exactly as the sample was treated 0.2880 gram of potassium permanganate dissolved in water was reduced to manganous sulphate by heating with sulphuric acid and a slight excess of oxalic acid, after which the solution was diluted to one liter. One cubic centi- meter of this solution contained, therefore, 0.100 milligram of manga- nese. 1 Gooch, P. A., and Austin, Martha, Die Bestiminung des Mangans als Sulfat und als Oxyd: Z. anorg. Chem., 17, 264-71 (1898). *Morse, H. N., Hopkins, A. J., and Walker, M. S.. The reduction of permanganic acid by manganese superoxide: Am. Chem. J., 18. 401-19 (1896). LEAD-PEROXIDE METHOD 9 LEAD-PEROXIDE METHOD The lead-peroxide method, first described by Crum 1 , has been used for a long time in iron and steel work. It has, however, been used only to limited extent in water analysis, and it has been largely supplanted by the bismuthate and persulphate methods. Of twelve investigators who have worked on the determination of manganese in water during the past ten years Klut 2 alone recommends this method. The majority favor the persulphate method and the bismuthate method seems to be second in popularity. No one, however, appears carefully to have compared the three methods. The material embodied in the section dealing with manganese in the report of the commit- tee 3 appears to have been based entirely upon the work of Klut 2 and of R. S. Weston. 4 TABLE 1. FIRST SERIES OF DETERMINATIONS OF MANGANESE BY THE LEAD-PEROXIDE METHOD. SOLUTIONS OF KNOWN CONTENT OF MANGANOUS CHLORIDE IN DISTILLED WATER COM- PARED WITH DILUTE STANDARD SOLUTION OF POTASSIUM PERMAGANATE. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard permanganate. Determined content. Theoretical content. Excess of deter- mined over theo- retical value. 0.0 0.0 0.00 0.00 +0.00 .2 .0 .00 .025 .025 .2 .0 .00 .025 .025 .4 .2 .02 .050 .03 .4 .2 .02 .050 .03 .6 .3 .03 .075 .045 .6 .4 .04 .075 .035 .8 .7 :07 .100 .03 .8 .6 .06 .100 .04 1.0 1.0 .10 .125 .025 1.0 1.0 .10 .125 .025 1.2 1.2 .12 .150 .03 1.2 1.3 .13 .150 .02 1.5 1.8 .18 .187 .007 1.5 1.8 .18 .187 .007 2.0 2.5 .25 .250 -+- .00 2.0 2.3 .23 .250 .02 2.5 . 2.8 .28 .312 .032 2.5 2.5 .25 .312 .062 3.0 3.5 .35 .375 .025 3.0 3.5 .35 .375 .025 3.5 4.0 .40 .438 .038 3.5 4.0 .40 .438 .038 4.0 4.5 .45 .500 .050 4.0 5.0 .50 .500 -+- .000 Mean .027 , Walter, Empfindliches Priifungsmittel auf Mangan: Ann., 55, 219-20 (1845). 2 Klut, H., Nachweis und Bestimmung von Mangan im Trinkwasser: Mitt. kgl. Priifungsamt. Wasserversorg. Abwasserbeseit., 12, 182-94 (1909). 'Standard methods for the examination of water and sewage, Am. Pub. Health Assoc , New York, 2nd ed., 49-51 (1912). 4 Weston, R. S., The determination of manganese in water: J. Am. Chem. Soc., 29, 1074-8 (1907). 10 MANGANESE IN WATER SUPPLIES The first series of experiments with the lead-peroxide method was carried out according to the following procedure. Different amounts of the standard manganous-chloride solution were diluted with distilled water, and evaporated in beakers with two or three drops of sulphuric acid until white fumes appeared. They were then diluted with water, acidified with 10 cubic centimeters of dilute nitric acid free from brown oxides of nitrogen, boiled down to a volume of 50 cubic centimeters, treated with 0.5 gram of lead peroxide, and boiled for five minutes. It was then filtered through an asbestos mat in a Gooch crucible, which had been ignited, treated with permanga- nate, and washed with water. The filtrate was transferred to a Nessler tube and the color was compared immediately with standards made by diluting the standard solution of potassium permanganate with water acidified with sulphuric acid. The results, shown in Table 1, indicate that the determined amounts of manganese were nearly all lower than the amounts actually present. The mean difference in the twenty-five determinations was 0.027 milligram. In order to check the possibility of error due to possible differ- ence in content of manganese between the solutions of manganous TABLE 2. SECOND SERIES OF DETERMINATIONS OF MANGANESE BY THE LEAD-PEROXIDE METHOD. SOLUTIONS OF KNOWN CONTENT OF POTASSIUM PERMANGANATE IN DISTILLED WATER COMPARED WITH DILUTE STANDARD SOLUTION OF POTASSIUM PERMANGANATE. Cubic centimeters of solution. , Milligrams of manganese. Potassium permanganate. Standard permanganate. Determined content. Theoretical content. Excess of deter- mined over theo- retical value. 0.0 0.0 0.00 0.00 + .00 .2 .0 .00 .02 .02 .2 .0 .00 .02 .02 .4 .15 .015 .04 .025 .4 .10 .01 .04 .03 .6 .3 .03 .06 .03 .6 .3 .03 .06 .03 .8 .4 .04 .08 .04 .8 .5 .05 .08 .03 1.0 .8 .08 .10 .02 1.0 .8 .08 .10 .02 1.2 1.0 .10 .12 .02 1.2 .9 .09 .12 .03 1.5 1.2 .12 .15 .03 1.5 1.2 .12 .15 .03 2.0 1.8 .18 .20 .02 2.0 2.0 .20 .20 -t- .00 2.5 2.2 .22 .25 .03 2.5 2.2 ' .23 .25 .02 3.0 2.2 .22 .30 .08 3.0 2.5 .25 .30 .05 3.5 3.0 .30 35 .05 3.5 3.2 .32 .35 .03 4.0 4.0 .40 .40 -t- .00 4.0 3.7 .37 .40 .03 Mean .027 LEAD-PEROXIDE METHOD 11 chloride and potassium permanganate the second series of determina- tions was made with diluted portions of the solution of potassium permanganate instead of the solution of manganous chloride. (See Table 2). These portions were treated like those reported in Table 1 and were then compared with standards prepared from the same solution of potassium permanganate. The average amount found was 0.027 milligram less than actually present although the differences were variable. When 0.00 to 0.10 milligram of manganese is pres- ent the error is as great as 50 per cent. Though the error is only about 10 per cent when 0.3 or 0.4 milligram is present it is still a serious error. These results indicate that either the oxidation to permanganate is incomplete or there is some reduc- tion in subsequent steps, as the color produced is not so deep as that produced by a standard solution of potassium permanganate diluted to an equivalent content of manganese. A third series of determinations (Table 3) was, therefore, made in which the standards for comparison were made from the solution of manganous sulphate treated in the same manner as the samples TABLE 3. THIRD SERIES OF DETERMINATIONS OF MANGANESE BY THE LEAD-PEROXIDE METHOD. SOLUTIONS OF KNOWN CONTENT OP MANGANOUS CHLORIDE IN DISTILLED WATER COM- PARED WITH DILUTE STANDARD SOLUTION OF MANGANOUS SUL- PHATE TREATED IN THE SAME MANNER. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard manganous sulphate. Determined content. Theoretical content. Excess of deter- mined over theo- retical value. 0.0 0.0 0.00 0.00 +0.00 .2 .0 .00 .025 .025 .2 .0 .00 .025 .025 .4 .6 .06 .050 + .01 .4 .4 .04 .050 .01 .6 .8 .08 .075 + .005 .6 .4 .04 .075 .035 .8 .2 .12 .100 + .02 .8 .5 .15 .100 f .05 1.0 .1 .11 .125 .015 1.0 .2 .12 .125 .005 1.2 .0 .10 .150 .05 1.2 .1 .16 .150 -r- .01 1.5 2.3 .23 .187 + .043 1.5 2.0 .20 .187 4- .013 2.0 1.8 .18 .250 .07 2.0 1.9 .28 .250 + .03 2.5 3.0 .30 .312 .012 2.5 3.2 .32 .312 -f .008 3.0 4.0 .40 .375 + .025 3.0 4.0 .40 .375 -f .025 3.5 3.5 .35 .438 .088 3.5 4.0 .40 .438 .038 4.0 5.0 .50 .500 .000 4.0 6.0 .60 .500 + .100 Mean .001 MANGANESE IN WATER SUPPLIES were treated on the supposition that standards thus prepared should be exactly comparable with the sample. The results obtained were, however, very erratic, some being too high and some too low. Even when carried out under conditions which were as nearly similar as possible checks could not be obtained, and the error was as great as 30 per cent in many tests. TABLE 4. FOURTH SERIES OF DETERMINATIONS OF MANGANESE BY THE LEAD-PEROXIDE METHOD. SOLUTIONS OF KNOWN CONTENT OF MANGANOUS CHLORIDE IN DISTILLED WATER COM- PARED WITH DILUTE STANDARD SOLUTION OF MANGANOUS SULPHATE TREATED IN THE SAME MANNER AND DECANTED INTO NESSLER TUBES. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard manganous sulphate. Determined content. Theoretical content. Excess of deter- mined over theo- retical value. 0.0 0.0 0.00 0.00 +0.00 .2 .2 .02 .025 .005 .2 .2 .02 .025 .005 .4 .5 .05 .050 -+- .00 .4 6 .06 .050 + .01 .6 .7 .07 .075 .005 .6 .8 .08 .075 + .005 .8 1.2 .12 .100 -f- .02 .8 1.0 .10 .100 -4- .00 1.0 1.2 .12 .125 .005 1.0 1.0 .10 .125 .025 1.2 1.4 .14 .150 .01 1.2 1.7 .17 .150 + .02 1.5 2.0 .20 .187 + .013 1.5 2.2 .22 .187 + -033 2.0 2.5 .25 .250 -f- .00 2.0 2.0 .20 .250 .05 2.5 3.5 .35 .312 + .038 2.5 3.0 .30 312 .012 3.0 4.0 .40 .375 + .025 3.0 4.5 .45 .375 -f .075 3.5 5.0 .50 .438 + .062 3.5 4.5 .45 .438 + .012 4.0 5.0 .50 .500 + .000 4.0 6.0 .60 .500 + .100 Mean + -012 The most probable source of error in the determination seemed to be in filtering through asbestos, as a very small amount of a reduc- ing agent, like organic matter or compounds of manganese in the filter medium, would easily affect such very dilute solutions of permanganate. In order to eliminate this factor the determinations were made without filtration. Series 4 (Table 4) was made with manganous chloride diluted with distilled water. The comparisons were made, after the treated solutions had been decanted into Nessler tubes, with standard solutions of manganous sulfate treated in all respects like the samples. Series 5 (Table 5) was like series 4 except that the comparison of the solutions was made in the original beak- LEAD-PEROXIDE METHOD 13 ers alter allowing the lead peroxide to settle. Series 6 (Table 6) was like series 5 except that the samples were prepared by adding the solution of manganous chloride to tap water instead of distilled water. The tap water is a bicarbonate water from deep wells ; it con- tains no manganese and practically no chloride or sulphate; it has a turbidity of 5 parts, a color of 15 parts, due to its content of iron and organic matter, and a content of iron of 2 parts per million. The results of these three series show much greater accuracy than those of the first three, in which the solutions were filtered through asbestos. In series 4, in which the comparisons were made after the supernatant liquid had been decanted into Nessler tubes, difficulty was experi- enced on account of incomplete settling of the lead peroxide, some was invariably decanted, thus causing a dark color, which obscured the color to be compared. In series 5, in which comparisons were made in the original beakers, this difficulty was not encountered. The colors can not be matched so accurately in beakers, however, as the relatively shallow depths of solution make the differences in color appear less marked. The determinations made with tap water in TABLE 5. FIFTH SERIES OF DETERMINATIONS OF MANGANESE BY THE LEAD-PEROXIDE METHOD. SOLUTIONS OP KNOWN CONTENT OF MANGANOUS CHLORIDE IN DISTILLED WATER COM- PARED WITH DILUTE STANDARD SOLUTION OP MANGANOUS SULPHATE TREATED IN THE SAME MANNER IN ORIGINAL BEAKERS. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard manganous sulphate. Determined content. Theoretical content. Excess of deter- mined over theo- retical value. 0.0 0.00 0.00 0.00 +0.00 .2 .2 .02 .025 .005 .2 .2 .02 .025 .005 .4 .5 .05 .050 -+- .00 .4 .4 .04 .050 .01 .6 .7 .07 .075 .005 .6 .6 .06 .075 .015 .8 1.2 .12 .100 + .02 .8 1.0 .10 .100 -+- .00 1.0 1.4 .14 .125 4- .015 1.0 1.1 .11 .125 .015 1.2 1.5 .15 .150 4- .00 1.2 1.4 .14 .150 .01 1.5 2.0 .20 .187 + .013 1.5 1.6 .16 .187 .027 2.0 2.5 .25 .250 +- .00 2.0 3.0 .25 .250 4- .00 2.5 3.5 .35 .312 + .038 2.5 3.0 .30 .312 .012 3.0 4.0 .40 .375 + .025 3.0 3.5 .35 .375 .025 3.5 4.5 .45 .438 + .012 3.5 4.0 .40 .438 .038 4.0 5.0 .50 .500 +- .000 4.0 5.0 .50 .500 .000 .002 14 MANGANESE IN WATER SUPPLIES series 6 are as accurate as those with distilled water. Manganese can, therefore, be determined with a fair degree of accuracy by the lead-peroxide method in waters which contain little chloride and organic matter. A content as small as 0.02 milligram can be detected in a volume of 50 cubic centimeters by comparison of colors in Ness- ler tubes. The presence of organic matter in large amounts causes error, but the error from this source in ordinary samples is inappreci- able as the results with tap water show. The presence of chloride, which has a reducing action on per- manganate, also causes an error. In order to determine how serious the effect due to chloride might be, series 7 (Table 7) w r as conducted, in which evaporation with sulphuric acid was omitted and 5 milli- grams of chloride as sodium chloride was added to tap water. Low results were generally obtained. The average deviation from the theoretical values is .015 milligram. When 10 and 25 milligrams of chloride were present no test whatever for manganese could be obtained. It is essential, therefore, that chloride be removed for serious errors are introduced even by the presence of small amounts TABLE 6. SIXTH SERIES OF DETERMINATIONS OF MANGANESE BY THE LEAD-PEROXIDE METHOD. SOLUTIONS OP KNOWN CONTENT OF MANGANOUS CHLORIDE IN TAP WATER COMPARED WITH DILUTE STANDARD SOLUTION OF MANGANOUS SULPHATE TREATED IN THE SAME MANNER IN ORIGINAL BEAKERS. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard manganous sulphate. Determined content. Theoretical content. Excess of deter- mined over theo- retical value. 0.0 0.0 0.00 0.00 +0.00 .2 .2 .02 .025 .005 .2 .2 .02 .025 .005 .4 .5 .05 .050 -+ .00 .4 .5 .06 .050 + .01 .6 .7 .07 .075 .005 .6 .8 ,08 .075 + .005 .8 1.0 .10 .100 -+- .00 .8 1.0 .10 .100 + .00 1.0 1.2 .12 .125 .005 1.0 1.4 .14 .125 + .015 1.2 1.5 .15 .150 4- .00 1.2 1.7 .17 .150 + .02 1.5 2.0 .20 .187 + -013 1.5 1.7 .17 .187 .017 2.0 2.0 .20 .250 .05 2.0 2.3 .23 .250 .02 2.5 3.0 .30 .312 .012 2.5 3.5 .35 .312 + .038 3.0 3.5 .35 .375 .025 3.0 4.0 .40 .375 + .025 3.5 4.0 .40 .438 .038 3.5 4.0 .40 .438 .038 4.0 5.0 .50 .500 -f- .000 4.0 5.0 .50 .500 .000 Mean .004 SODIUM-BISMUTHATE METHOD 15 of that radicle. Chloride is present in many natural waters in amounts greater than those used in these experiments. THE SODIUM-BISMUTHATE METHOD Schneider 1 appears to have been the first to use bismuth perox- ide for the oxidation of manganous salts to permanganate. Other workers found, however, that the presence of chloride in this oxide was deleterious, and to overcome this trouble Reddrop and Ramage 2 substituted sodium bismuthate, which could be more easily obtained free from chloride. The bismuthate method has been used widely in analysis of iron and steel and has been shown to be accurate. It is described by Dufty, 3 Blair, 4 Blum, 5 Hillebrand and Blum, 6 and others. Weston 7 first advocated it for use in water analysis in 1907, TABLE 7. SEVENTH SERIES OF DETERMINATIONS OF MANGANESE BY THE LEAD-PEROXIDE METHOD. SOLUTIONS OF KNOWN CONTENT OF MANGANOUS CHLORIDE IN TAP WATER COMPARED WITH DILUTE STANDARD SOLUTION OF MANGANOUS SULPHATE IN THE PRESENCE OF 5 MILLIGRAMS OF CHLORIDE. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard manganous sulphate. Determined content. Theoretical content. Excess of deter- mined over theo- retical value. 0.0 0.0 0.00 0.00 +0.00 .2 2 .02 .025 .005 .2 '.2 .02 .025 .005 .4 .3 .03 .050 .02 .4 .4 .03 .050 .02 .6 .5 .05 .075 .025 .6 .6 .06 .075 .015 .8 .7 .07 .100 .03 .8 .9 .09 .100 .01 1.0 1.1 .11 .125 .015 1.0 1.2 .12 .125 .005 1.2 1.2 .12 .150 .03 1.2 1.4 .14 .150 .01 1.5 1.8 .18 .187 .007 1.5 2.0 .20 .187 + .013 2.0 2.5 .25 .250 -4- .000 2.0 2.0 .20 .250 .05 2.5 3.0 .30 .312 .012 2.5 3.0 .30 .312 .012 3.0 3.5 .35 .375 .025 3.0 3.5 .35 .375 .025 Mean ... .015 1 Schneider, L., Methode zur Bestimmung von Mangan: Dingl. poly. J. 269, 224 (1888). 2 Reddrop, Joseph, and Ramage, Hugh, Volumetric estimation of manganese: J. Chem. Soc., 67, 268-77 (1895). 3 Dufty, Lawrence, Volumetric estimation of manganese: Chem. News, 84, 248 (1901). 4 Blair, A. A., The bismuthate method for the determination of manganese: J. Am. Chem. Soc., 26, 793-801 (1904). 5 Blurn, William, Determination of manganese as sulphate and by the sodium-bismuthate method: Orig. Com. 8th Intern. Congr. Appl. Chem., 1, 61-85 (1912). 'Hillebrand, W. F., and Blum, William, The determination of manganese by the sodium- bismuthate method: J. Ind. Eng. Chem., 3, 374-6 (1911). 7 Weston, R. S. f The determination of manganese in water: J. Am. Chem. Soc., 29, 1074-8 (1907). 16 MANGANESE IN WATER SUPPLIES before which year manganese in water was seldom determined. He describes the method, giving some data which show it to be sufficient- ly accurate. The procedure for this method recommended by the committee on standard methods of water analysis 1 in the edition pub- lished in 1912 is based on Weston's work. The procedure used in this investigation is essentially as fol- lows. Different amounts of the standard solution of manganous chloride were diluted with distilled water and with tap water. Each portion was then evaporated with one or two drops of sulphuric acid (1 to 3) until white fumes appeared. Distilled water, dilute nitric acid, and 0.5 gram of sodium bismuthate were then added, after which the solution was heated until the pink color disappeared. After it had cooled somewhat an excess of sodium bismuthate was added, the solu- tion was thoroughly stirred, then filtered through an asbestos mat in a Gooch crucible, which had been washed, ignited, and treated with potassium permanganate. The solution was then transferred to a Nessler tube and compared with two sets of standards, one prepared TABLE 8. FIRST SERIES OF DETERMINATIONS OF MANGANESE BY THE BISMUTHATE METHOD. SOLUTIONS OF KNOWN CONTENT OF MANGANOUS CHLORIDE IN DISTILLED WATER COMPARED WITH DILUTE STANDARD SOLUTION OF POTASSIUM PERMANGANATE. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard permanganate. Determined content. Theoretical content. Excess of deter- mined over theo- retical content. 0.0 0.0 0.00 0.00 -f-0.00 .2 .2 .02 .025 .005 .2 .2 .02 .025 .005 .4 .4 .04 .050 .01 .4 .5 .05 .050 + .00 .6 .7 .07 .075 .005 .6 .7 .07 .075 .005 .8 1.0 .10 .100 -f- .00 .8 1.0 .10 .100 -+- .00 1.0 1.2 .12 .125 .005 .0 1.2 .12 .125 .005 .2 1.5 .15 .150 -t- .00 .2 1.4 .14 .150 .01 .5 2.0 .20 . .187 + .013 .5 1.7 .17 .187 .017 2.0 2.5 .25 .250 + .00 2.0 2.2 .22 .250 .03 2.5 3.0 .30 .312 .012 2.5 3.2 .32 .312 + .008 3.0 3.5 .35 .375 .025 3.0 4.0 .40 .375 + .025 3.5 4.5 .45 .438 + .012 3.5 4.5 .45 .438 + .012 4.0 5.0 .50 .500 -f- .000 4.0 5.0 .50 .500 -4- .000 Mean .003 1 Standard methods for the examination of water and sewage, Am. Pub. Health Assoc., New York, 2nd ed., 49-51 (1912). SODIUM-BISMUTHATE METHOD 17 by diluting standard potassium permanganate and the other by treat- ing standard solutions of manganous sulphate like the samples. The results obtained are shown in Tables 8 and 9. A third series (Table 10) was run in the same manner except that tap water was used in- stead of distilled water. Filtration through asbestos does not seem to have any appreciable reducing effect on the permanganate when sodium bismuthate is used as the oxidizing agent. This seems strange for when lead peroxide was used the effect was so great as to cause uniformly low values. The results indicate that the bismuthate method is accurate under all the conditions here observed. A content of 0.01 milligram of manganese in a volume of 50 cubic centimeters can be detected by comparison in Nessler tubes. In order to determine how seriously the results are affected by the presence of chloride 5, 10, and 25 milligrams of chloride as sodium chloride were added to different portions, and evaporation with sulfuric acid was omitted. The determinations made under these conditions are shown in Table 11. The results indicate that chloride has no appreciable effect in amounts of 5 milligrams or less. TABLE 9. SECOND SERIES OF DETERMINATIONS OP MANGANESE BU THE BISMUTHATE METHOD. SOLUTIONS OF KNOWN CONTENT OF MANGANOUS CHLORIDE IN DISTILLED WATER COMPARED WITH DILUTE STANDARD SOLUTION OF MANGANOUS SULPHATE TREATED IN THE SAME MANNER. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard manganous sulphate. Determined content. Theoretical content. Excess of deter- mined over theo- retical content. 0.0 0.0 0.00 0.00 0.00 .2 .2 .02 .025 .005 .2 .2 .02 .025 .005 .4 .4 .04 .050 .01 .4 .5 .05 .050 -t- .00 .6 .7 .07 .075 .005 .6 .8 .08 .075 + .005 .8 1.0 .10 .100 .00 .8 1.0 .10 .100. + .00 1.0 1.2 .12 .125 .005 1.0 1.1 .11 .125 .015 1.2 1.5 .15 .150 -f- .00 1.2 1.4 .14 '.150 .01 1.5 2.0 .20 .187 + .013 1.5 2.0 .20 .187 4- .013 2.0 2.5 .25 .250 + .00 2.0 2.5 .28 .250 + .03 2.5 3.0 .30 .312 .012 2.5 3.5 .35 .312 -f .038 3.0 3.5 .35 .375 .025 3.0 4.0 .40 .375 4- .025 3.5 4.5 .45 .438 -f .012 3.5 4.0 .4a .438 .038 4.0 5.0 .50 .500 + .000 4.0 5.0 .50 .500 .000 Mean + .0002 18 MANGANESE IN WATER SUPPLIES When 10 milligrams or more of chloride are present the results are low. The effect of chloride in the bismuthate method is much less pronounced than in the peroxide method, in which the presence of more than 10 milligrams of chloride wholly prevented the appearance of the color of permanganate. The bismuthate method is decidedly superior to the lead-peroxide method. The color of the permanganate is not appreciably weakened by filtration through asbestos. Comparison of colors may, therefore, be made by filtering and transferring to Nessler tubes. The presence of chloride does not interfere so seriously in the bismuthate as in the lead-peroxide method. That the permanganate is not so easily re- ducible in the presence of sodium bismuthate as in the presence of lead peroxide is probably due to the fact that the bismuthate is a more active oxidizing agent than the peroxide. The results were as accurate when the colors were compared with those of dilute standard solutions of potassium permanganate as when compared with those of solutions of manganous sulphate treated like the samples. The TABLE 10. THIRD SERIES OF DETERMINATIONS OP MANGANESE B\ THE BISMUTHATE METHOD. SOLUTIONS OP KNOWN CONTENT OF MANGANOUS CHLORIDE IN TAP WATER COMPARED WITH DILUTE STANDARD SOLUTION OP MANGANOUS SULPHATE TREATED IN THE SAME MANNER. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard manganous sulphate. Determined content. Theoretical content. Excess of deter- mined over theo- retical content. 0.0 0.0 0.00 0.00 +0.00 .2 .2 .02 .025 .005 .2 .3 .03 .025 + .005 .4 .5 .05 .050 -f- .00 .4 .5 .05 .050 -+- .00 .6 .8 .08 .075 + .005 .6 .7 .07 .075 .005 .8 .10 .10 .100 -4- .00 .8 .08 .08 .100 .02 1.0 .12 .12 .125 .005 1.0 .11 .11 .125 + .015 1.2 .15 .15 .150 +- .00 1.2 .15 .15 .150 -t- .00 1.5 2.0 .20 .187 4- .013 1.5 1.8 .18 .187 .007 2.0 2.5 .25 .250 -+ .00 2.0 2.2 .22 .250 .03 2.5 3.0 .30 .312 .012 2.5 3.5 .35 .312 + .038 3.0 4.0 .40 .375 + .025 3.0 4.0 .40 .375 + .025 3.5 4.5 .45 .438 4- .012 3.5 4.0 .40 .438 .038 4.0 5.0 .50 .500 -+- .000 4.0 5.0 .50 .500 .000 Mean + .001 PERSULPHATE METHOD 19 use of sodium bismuthate permits detection of a slightly smaller amount of manganese than the use of lead peroxide. THE PERSULPHATE METHOD The fact that persulphate oxidizes manganous salts to perman- ganate in the presence of silver nitrate was discovered by Marshall 1 , who suggested the reaction as a qualitative test for manganese. Walters 2 first used a modified form of the method for the quantita- tive determination of manganese in iron and steel. After the man- ganese had been oxidized to permanganate the amount was found by titrating with arsenious acid. This method is now widely used in metallurgical work. In water analysis comparison of the colors of the solutions of permanganate is usually made instead of a titration. The persulphate TABLE 11. FOURTH SERIES OF DETERMINATIONS OP MANGANESE BY THE BISMUTHATE METHOD. SOLUTIONS OF KNOWN CONTENT OP MANGANOUS CHLORIDE IN DISTILLED WATER CONTAINING CHLORIDE COMPARED WITH DILUTE STANDARD SOLUTION OF POTASSIUM PERMANGANATE. [Results expressed in milligrams of manganese.] Solution of manganous chloride. Theoretical content. Determined content of manganese in presence of designated amounts of chloride. 5 mg. | 10 mg. 25 mg. 50 mg. Cubic centimeters 0.0 0.000 0.00 0.00 0.00 0.00 .2 .025 .02 .02 .00 .00 .2 .025 .03 .02 .00 .00 .4 .050 .05 .04 .03 .00 .4 . * .050 .05 .03 .02 .00 .6 .075 .08 .07 .05 .03 .6 .075 .07 .08 .06 .04 .8 .100 .10 .09 .08 .05 .8 .100 .10 .10 .07 .05 1.0 .125 .12 .12 .10 .08 1.0 .125 .14 .12 .08 .10 1.2 .150 .15 .14 .14 .12 1.2 .150 .15 .13 .12 .10 1.5 .187 .20 .17 .15 .12 1.5 .187 .20 .15 .15 .15 2.0 .250 .25 .20 .20 .12 2.0 .250 .30 .25 .20 .20 2.5 .312 .30 .30 .25 .25 2.5 .312 .28 .32 .28 .20 3.0 .375 .35 .32 .30 .30 8.0 .375 .40 .32 .32 .25 8.5 .433 .45 .40 .40 .20 3.5 .438 .45 .35 .30 .20 4.0 .504 .50 .45 .37 .25 4.0 .504 .40 .45 .40 .20 Marshall, Hugh, The detection and estimation of minute quantites of manganese: Chem. News, 83, 76 (1901). ^Walters, H. E., Ammonium persulphate as a substitute for lead peroxide in the colori- metric estimation of manganese: Chem. News, 84, 239-40 (1901). 20 MANGANESE IN WATER SUPPLIES method has been advocated by Liihrig and Becker, 1 Kodenburg, 2 Haas, 3 Schowalter, 4 Hartwig and Schellbach, 5 and Tillmans and Mildner 6 , but most of these authors present no data as to the accu- racy of the method. In the writer's work with the ammonium-persulphate method different amounts of the standard solution of manganous chloride were diluted with distilled water or with tap water to about 50 cubic centimeters each. Two cubic centimeters of nitric acid (1 to 1) and .5 cubic centimeters of 2.0 per cent solution of silver nitrate were added. After the mixture had been boiled and shaken it was filtered. About 0.5 gram of crystals of ammonium persulphate was added to the filtrate, and the solution was heated gently on the hot plate until the maximum color of permanganate had developed after which it was transferred to a 50 cubic centimeter Nessler tube. The color was compared with those of standards prepared by diluting with water a standard solution of potassium permanganate or by treating diluted amounts of a standard solution of manganous sulphate with nitric acid, silver nitrate, and ammonium persulphate like the sample. The TABLE 12. FIRST SERIES OF DETERMINATIONS OF MANGANESE BY THE PERSULPHATE METHOD. SOLUTIONS OP KNOWN CONTENT OP MANGANOUS CHLORIDE IN DISTILLED WATER COMPARED WITH DILUTE STANDARD SOLUTION OF POTASSIUM PERMANGANATE. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard permanganate. Determined content. Theoretical content. Excess of deter- mined over theo- retical content. 0.0 0.0 0.00 0.00 -f-0.00 .2 .2 .02 .025 .005 .2 .3 .03 .025 + .005 .4 .4 .04 .050 .01 .4 .5 .05 .050 4- .00 .6 .7 .07 .075 .005 .6 .7 .07 .075 .005 .8 1.0 .10 .100 -4- .00 .8 1.1 .11 .100 -f .01 1.0 1.2 .12 .125 .005 1.0 1.0 .10 .125 .025 Mean .003 Liihrig, H., and Becker, W., Zur Bestimmung des Mangans im Trinkwasser: Pharm. Zentralhalle, 48, 137-42 (1907). 2 Rodenburg, J., Over mangaanbepaling in leidingwater : Chem. Weekblad, 7, 877-9 (1910). 8 Haas, Fritz, Ueber die colorimetrische Bestimmung kleiner Mengen von Mangan im Trinkwasser: Z. Nahr. Genussm., 25, 392-5 (1913). 4 Schowalter, E., Colorimetrische Bestimmung kleiner Mengen von Mangan im Trink- wasser: Z. Nahr. Genussm., 26, 104-8 (1913); also Studien zur Kenntnis des Verlaufs der Marshall' schen Manganreaktion : 27, 553-62 (1914). B Hartwig, L., and Schellbach, H., Colorimetrische Bestimmung von kleinen Mengen Man- gan in Trinkwasser: Z. Nahr. Genussm., 26, 439-42 (1913). "Tillmans, J., and Mildner, H., Mangan im Wasser, sein Nachweis und seine Bestimmung : J. Gasbel., 67, 496-501, 523-6, 544-7 (1914). PERSULPHATE METHOD 21 results obtained by comparison of colors according to these methods are given in Tables 12, 13, 14, and 15. In the comparisons with standard solution of potassium perman- ganate diluted with water (Table 12) amounts of manganese greater than 0.125 milligram could not be compared easily on account of the difference in shade between the standards of permanganate and the samples. The solutions of potassium permanganate were reddish purple while the samples were bluish purple. This difference in hue was noticeable in all the concentrations used, but it did not cause great trouble except when the manganese is present in amounts great- er than 0.10 or 0.12 milligram. With lower concentrations accurate results were obtained, but with higher concentrations the comparison was too unsatisfactory to be used. When the standards were prepared by treating diluted solutions of manganous sulphate in the same manner as the samples, no diffi- culty was experienced in making the comparisons, and the results (Tables 13 and 14) show that the method is accurate. Series 3 in which the solution of manganous chloride was diluted with tap water TABLE 13. SECOND SERIES OF DETERMINATIONS OF MANGANESE BY THE PERSULPHATE METHOD. SOLUTIONS OF KNOWN CONTENT OF MANGANOUS CHLORIDE IN DISTILLED WATER COMPARED WITH DILUTE STANDARD SOLUTION OF MANQANOUS SUL- PHATE TREATED IN THE SAME MANNER. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard manganous sulphate. Determined content. Theoretical content. Excess of deter- mined over theo- retical content. 0.0 0.0 0.00 0.00 +0.00 .2 .2 .02 .025 .005 .2 .25 .025 .025 -l- .00 .4 .6 .06 .050 + .01 .4 .5 .05 .050 -1- .00 .6 .7 .07 .075 .005 .6 .8 .08 .075 + .005 .8 1.0 .10 .100 -+- .00 .8 1.1 .11 .100 -f .01 1.0 1.2 .12 .125 .005 1.0 1.2 .12 .125 .005 1.2 1.4 .14 .150 .01 1.2 1.4 .16 .150 + .01 1.5 1.8 .18 .187 .007 1.5 1.8 .18 .187 .007 2.0 2.4 .24 .250 .01 2.0 2.5 .25 .250 -+- .00 2.5 3.0 .30 .312 .012 2.5 3.3 .33 .312 -f .018 3.0 3.5 .35 .375 .025 3.0 3.8 .38 .375 + .005 3.5 4,0 .40 .438 .038 3.5 4.5 .45 .438 -f .012 4.0 5.0 .50 .500 H- .000 4.0 4.5 .45 .500 Mean . .050 .004 22 MANGANESE IN WATER SUPPLIES gave as accurate results as those in which distilled water was used, the mean differences for the two series of twenty-five determinations each being, respectively, 0.003 milligram and 0.004 milligram. The results show the desirability of using standards which have been oxidized with persulphate and treated in all respects like the samples. A content of 0.005 milligram of manganese in a volume of 50 cubic centimeters was easily detected under the conditions of the test. Liihrig 1 states that a high content of chloride interferes in the persulphate method by causing a blue coloration, and that iron inter- feres by causing a reddish coloration. Yet accurate results were ob- tained by the writer in a series of determinations in which 50, 100, and 200 milligrams of chloride as sodium chloride were present. ( See Table 15.) No bluish coloration was noted, and no difficulty was experienced in matching the colors. A large excess of silver nitrate and ammonium persulphate should be avoided as it seems to produce a cloudiness perhaps by precipitate of silver peroxide. Mar- TABLE 14. THIRD SERIES OF DETERMINATIONS OF MANGANESE BY THE PERSULPHATE METHOD. SOLUTIONS OP KNOWN CONTENT OP MANGANOUS CHLORIDE IN TAP WATER COMPARED WITH DILUTE STANDARD SOLUTION OP MANGANOUS SULPHATE TREATED IN THE SAME MANNER. Cubic centimeters of solution. Milligrams of manganese. Manganous chloride. Standard manganous sulphate. Determined content. Theoretical content. Excess of deter- mined over theo- retical content. 0.0 0.0 0.00 0.00 +0.00 .2 .3 .03 .025 + -005 .2 .2 .02 .025 .005 .4 .5 .05 .050 -t- .00 .4 .5 .05 .050 -t- .00 .6 .7 .07 .075 .005 .6 .7 .07 .075 .005 .8 .9 .09 .100 .010 .8 1.0 .10 .100 -f- .000 1.0 1.2 .12 .125 .005 1.0 1.1 .11 .125 .015 1.2 1.4 .14 .150 .01 1.2 1.5 .15 .150 -4- .00 1.5 1.8 .18 .187 .007 1.5 1.9 .19 .187 + .003 2.0 2.5 .25 .250 +- .00 2.0 2.4 .24 .250 .01 2.5 3.2 .32 .312 + .008 2.5 3.3 .33 .312 + .018 3.0 3.5 .35 .375 .025 3.0 3.8 .38 .375 + .005 3.5 4.5 .45 .438 + .012 3.5 4.5 .45 .438 -I- .012 4.0 5.0 .50 .500 + .000 4.0 4.7 .47 .500 .030 Mean .003 a Luhrig, H., Die colorimetrische Bestimmung kleiner Manganmengen im Wasser: Ztg., 38, 781-3 (1914). Chem. COMPARISON OF METHODS 23 shall 1 prepared silver peroxide by this method, and the interference noted by Liihrig is probably caused thus. Large amounts of iron doubtless interfere on account of the yellow color of ferric salts. When manganese is present the mixture produces the reddish coloration noted by Liihrig. COMPARISON OF THREE COLORIMETRIC METHODS In order to compare the three colorimetric methods for deter- mination of manganese under working conditions, the manganese in several natural waters was determined by each method. The amounts found, together with the amounts of residue, chloride, iron, and the alkalinity to show the character of the waters, are given in Table 16. The samples were taken below Streator from Vermilion River, which is polluted by coal-mine drainage, and their contents of iron and chlo- ride are large. In the persulphate method chloride was precipi- tated by silver nitrate, added in slight excess, and was removed by filtration. The colorimetric comparison was made with standard TABLE 15. FOURTH SERIES OF DETERMINATIONS OF MANGANESE BY THE PERSULPHATE METHOD. SOLUTIONS OF KNOWN CONTENT OF MANGANOUS CHLORIDE IN TAP WATER CONTAINING CHLORIDE COMPARED WITH STANDARD SOLUTION OF MANGANOUS SUL- PHATE TREATED IN THE SAME MANNER. [Results expressed in milligrams of manganese.] Solution of manganous chloride. Theoretical content. Determined content of manganese in presence of designated amounts of chloride. 50 mg. 100 mg. 200 mg. Cubic centimeters. 0.0 0.000 0.000 0.000 0.000 .2 .025 .02 .02 .02 .2 .025 .02 .02 .02 .4 .050 .04 .05 .04 .4 .050 .05 .05 .05 .6 .075 .07 .07 .08 .6 .075 .08 .07 .08 .8 .100 .11 .09 .10 .8 .100 .10 .10 .10 1.0 .125 .12 .13 .12 1.0 .125 .12 .12 .12 1.2 .150 .14 .15 .16 1.2 .150 .16 .16 .15 1.5 .180 .18 .19 .17 1.5 .180 .20 .20 .19 2.0 .250 .22 . .22 .25 2.0 .250 .25 .24 .25 2.5 .312 .30 .30 .32 2.5 .312 .28 .30 .30 3.0 .375 .35 .35 .40 3.0 .375 .40 .35 .40 3.5 .438 .45 .40 .45 3.5 .438 .45 .45 .50 4.0 .504 .50 .45 .55 4.0 .504 1 .50 .50 .50 1 Marshall, Hugh, The action of silver salts on solution of ammonium persulphate: Proc. Royal Soc. Edinburgh, 23, 163-8 (1900). 24 MANGANESE IN WATER SUPPLIES solution of manganous sulphate treated in the same manner as the sample. In the bismuthate method evaporation of the sample with sulphuric acid was omitted, and the colorimetric comparison was made with standards prepared by diluting the standard solution of potassium permanganate. In the lead-peroxide method the tests were made with and without nitration through Gooch crucibles and "with and without evaporation with sulphuric acid, and standards were pre- pared by treating portions of the dilute solution of manganous sul- fate in the same manner as the samples. The amounts determined by the persulphate and the bismuthate methods agree very well. The amounts found by the lead-peroxide method with chloride removed and without filtering through Gooch crucibles also agree very well with those obtained in the persulphate and the bismuthate methods. The results were low, however, when chloride was not first removed and irregular results were obtained when the Gooch crucible was used for filtration. TABLE 16. DETERMINATIONS OF MANGANESE IN NATURAL WATERS BY COLORIMETRIC METHODS. [Parts per million.] Manganese (Mn). Lead-peroxide method. Total residue. Chloride (01). Alkalinity as Ca CO 3 . Iron (Fe). Persul- phate method. Bismu- thate method. Gooch crucible. Decantation. Chlo- Chlo- Chlo- Chlo- rine rine rine rine not re- re- not re- re- moved. moved. moved. moved. 848 42 460 0.4 0.25 0.15 0.0 0.0 0.2 0.2 2328 60 20 150. 4.5 4.0 3.0 3.0 4.0 5.0 2070 80 20 86. 4.0 3.2 2.0 4.8 3.0 4.0 2290 83 26 90. 4.0 4.2 2.5 3.2 3.0 4.0 2198 84 40 65. 5.5 5.0 3.0 5.0 5.0 5.0 2371 103 60 66. 7.5 7.0 6.0 7.0 7.0 8.0 2293 103 122 4.0 8.0 9.5 4.0 6.0 6.0 8.0 345 25 144 .2 .0 .0 .0 .0 2396 102 90 46.5 9.0 8.5 6.0 7'. 6 8.0 7'. 6 1591 17 92 126.5 1.4 1.4 0.6 1.6 1.0 1.5 2660 65 200 57.5 2.0 1.8 1.8 2.0 2.0 2.0 1970 92 4 48.0 4.0 4.0 2.0 6.0 3.0 4.0 RELATIVE VALUE OF COLORIMETRIC METHODS The persulphate method is the most convenient and accurate method for the colorimetric determination of manganese in water. Chloride, being necessarily removed by precipitation, does not inter- fere. As small amount as 0.005 milligram of manganese in a volume of 50 cubic centimeters, equivalent to 0.1 part per million, can be de- tected. The bismuthate method recommended by the committee on OCCURRENCE 25 standard methods of water analysis 1 is accurate and reliable. The presence of chloride in amounts less than 5 milligrams does not in- terfere with this determination, and evaporation with sulphuric acid may be omitted unless the water contains much organic matter. By this method 0.01 milligram of manganese in a volume of 50 cubic centimeters, equivalent to 0.2 part per million, can be detected. The lead-peroxide method accepted by the committee on standard methods of water analysis gives results which are seriously low be- cause of reduction of permanganate in using the Gooch crucible. If this step is omitted more nearly accurate results are obtained. The presence of chloride interferes in this method more seriously than in either of the others, and if more than 5 milligrams of chloride are present no manganese may be found even if a comparatively large amount is present; evaporation with sulphuric acid is, therefore, necessary. About 0.02 milligram of manganese in a volume of 50 cubic centimeters, equivalent to 0.4 part per million, can be detected by the decantation method. The peroxide method is at best the least sensitive of the three, and it should be rejected as a standard method. It seems advisable to adopt as standard: (1) The persulphate method, in which colorless nitric acid should be used, evaporation with sulphuric acid should be omitted unless large amounts of organic matter are present, and comparison should be made with standards prepared by treating solutions of manganous sulphate exactly like the sample ; (2) The bismuthate method, in which colorless nitric acid should be used, evaporation with sulphuric acid should be omitted unless more than 5 milligrams of chloride or much organic matter is present, and comparison should be made with standards prepared by treating standard solutions of manganous sulphate exactly like the sample or by diluting a freshly prepared solution of potassium permanganate. MANGANESE IN WATER SUPPLIES General occurrence The presence of manganese in water supplies in concentrations great enough to be significant has always been considered rather un- usual, particularly in the United States. Manganese has been en- countered in several water supplies in Europe. Standard methods for the examination of water and sewage, Am. Pub. Health Assoc., New York, 2nd ed., 49-51 (1912). 26 MANGANESE IN WATER SUPPLIES R. S. Weston 1 cites some twenty ground-water supplies in this country and in Europe which have been reported to contain man- ganese. TABLE 17. MANGANESE IN CERTAIN MUNICIPAL WATER SUPPLIES. Parts per million. Arad, Hungary Present Babylon, N. Y 07 Bayshore, N. Y 37 Berlin, Germany Present Bjornstorp, Sweden 3.4 53.4 Brunswick, Germany Present Breslau, Germany Trace 110 Calverton, N. Y 30 Halle, Germany 1.50 Hamburg, Hofbriinnen 45 Hanover, Germany Present Patchogue, N. Y 20 Beading, Mass 004 .56 Stargard, Germany Present Stettin, Germany 5.22 Superior, Wisconsin 12 Shewsbury, Mass 10 The first water in this country in which manganese was reported in sufficient quantity to cause trouble was, from a well supplying a New England mill in 1898. This supply was abandoned because of its high content of manganese. Sixty-two springs in the United States are listed by Mason 2 as having been reported to contain manganese. He states that nearly half of them contain only traces of the element and that only seven contain as much as the 4.5 parts per million which he found in a mineral spring at Excelsior Springs, Mo. Kaumer 3 reports a water near Fiirth which contained 6.2 parts per million of manganese. Bailey 4 states that the well-water supply of Hutchinson, Kans., contains 1.0 part per million of manganese. 1 Weston, E. S., The purification of ground waters containing iron and manganese : Trans. Am. Soc. 0. E., 64, 112-81 (1909). ^ason, W. P., The manganese waters of Excelsior Springs: Chem. News, 61, 123 (1890). 8 Raumer, E. von, Ueber das Auftreten von Eisen und Mangan in Wasserleitungswasser : Z. anal. Chem., 42, 590-602 (1903). *Bailey, E. H. S., Occurrence of manganese in a deposit found in city water pipes: J. Am. Chem. Soc., 26, 714-5 (1904). OCCURRENCE 27 The trouble in Breslau 1 in 1906 is a classic example of injury to a water supply by very high contents of iron and manganese. Breslau was formerly supplied with water from Oder River, but in 1905 a supply was substituted from 313 driven wells 30 to 40 feet deep in Oder valley. In March, 1906, the Oder overflowed its banks, and soon afterward the turbidity, odor, hardness, residue, manganese, and iron in the ground- water supply enormously increased. The con- tent of iron increased to 440 and the content of manganese to 220 parts per million. The filtered water from Oder River was necessarily substituted for the ground- water supply. Many explanations have been offered for this peculiar change in the quality of the water. Most authorities agree that it was caused by a process of oxidation and leaching of the soil, which contains a large amount of sulfides of iron and manganese. The iron sulfide was oxidized to iron sulfate by the dissolved oxygen of the river water. The water containing iron sul- phate then percolated through the soil to the water-bearing strata, a part hydrolyzing to sulphuric acid which dissolved the manganese. Extensive experiments on the removal of iron and manganese from the supply have been carried on by a number of investigators. Manganese waters at Bjornstorp Estate, Sweden, are described by Weibull. 2 Pipes were clogged, and fabrics laundered in several waters from ponds and wells in the vicinity were turned yellow. In- vestigation showed that some of the waters contained as much as 6.3 parts per million of manganous oxide, or 5 parts per million of man- ganese which was precipitated upon exposure to the air. The rock formation in the vicinity is gneiss and diorite, the latter of which contains 8.2 per cent of manganous oxide, which probably accounts for the high content of manganese of the waters. A study of the content of manganese of waters in France has been made by Jadin and Astrug. 3 In several city supplies 0.0005 to 0.015 part per million of manganese was found. Mineral waters at Vichy and Boulon contained 0.09 to 0.20 part per million. The content of manganese of sources very near each other widely differed. 1 Woy, Rudolph, Stoning der Breslauer Wasserversorgung durch Mangansulf at : Z. offent. Chem. 12. 121-125 (1906) ; Kritische Besprechung der Erfahrungen mit JLer Breslauer Grundwasserversorgung : 13, 401-411 (1907). Liihrig, H., t)ber die Ursachen der Breslauer Grundwasserverschlechterung und die Mittel zu ihrer Behelung: Z. Nahr. Genussm., 14, 40-63 (1907). Beyschlag, F., and Michael R., Uber die Grundwasserverhaltnisse der Stadt Breslau: Z. prakt. Geol., 15, 153-64 (1907). Luhrig, H. and Blasky, A., Mangan in Grundwasser der Breslauer Wasserleitung und die Frage der Abscheidung des Mangansulf ates aus demselben: Chem. Ztg., 31, 255-7 (1907). Weston, R. S., The purification of ground waters containing iron and manganese: Trans. Am. Soc. 0. E., 64, 112-81 (1909). 2 Weibull, Mats, Ein manganhaltiges Wasser und eine Bildung von Braunstein bei Bjornstorp in Sweden. Z. Nahr. Genussm., 14, 403-5 (1907). 8 Jadin, F., and Astrug, A., Le manganese dans les eaux d' alimentation et lea eaux minerals: Compt. Rend., 157, 338-9 (1913). 28 MANGANESE IN WATER SUPPLIES Discovery of manganese in several city water supplies of Illi- nois prompted an investigation to determine what relations, if any, exist between geological formation and content of manganese and to determine the source of the manganese in the supplies. Accordingly, manganese, iron, and dissolved solids were determined in a large number of samples from representative sources throughout the State. Samples were taken from streams and from wells, concerning which reliable information was available concerning the geological strata penetrated. As complete information of this kind concerning many private wells is not available whereas rather complete logs are usually kept of city wells most of the supplies examined are city water sup- plies. The samples were taken at the original sources, preliminary work having shown that manganese may completely separate in the pipes before the water reaches distant taps. Methods of Analysis MANGANESE The colorimetric persulfate method was used for the determina- tion of manganese. Two hundred and fifty cubic centimeters of the sample were acidified with 2 cubic centimeters of nitric acid (1 to 1) and concentrated to a volume of less than 50 cubic centimeters. If the sample contained more than 0.20 milligram of manganese a smaller amount was used for the determination. Surface waters and in general waters showing a clayey or silica-like turbidity were filtered before making the determination. After concentration chloride was pre- cipitated with a solution of silver nitrate added in slight excess, and the precipitate was removed by filtration. Samples which were very high in chloride were evaporated with sulphuric acid until white fumes were evolved, after which distilled water and a small amount of the solution of silver nitrate were added. One-half gram of crystals of ammonium persulphate was then added, and the solution was warmed until the maximum color of permanganate had developed. Standards were prepared containing 0.2, 0.4, 0.6, and more cubic centi- meters of standard solution of manganous sulphate, which was diluted to similar volume and treated in exactly the same manner as the sample was treated. The sample and the standards were then transferred to 50-cubic centimeter Nessler tubes and the colors were compared. If the above procedure is followed the limit of detection is 0.02 part per million. OCCURRENCE 29 IRON Iron was determined either colorimetrically with potassium sul- phocyanide or by titration with permanganate after the weighed oxides of iron and aluminium had been fused and dissolved. DISSOLVED SOLIDS Dissolved solids is the residue obtained by evaporating to dryness 100 cubic centimeters of the sample, heating the residue at 180 C. for one hour, and weighing it. Samples having a clayey or silica-like tur- bidity were filtered before evaporation. If the turbidity was due to precipitated ferric hydroxide the sample was not filtered. Manganese in Waters of Illinois The supplies have been grouped as follows with reference to source : 1. Wells in Potsdam sandstone. 2. Wells in St. Peter sandstone. 3. Wells in limestone. 4. Wells in unconsolidated deposits. 5. Springs. 6. Coal-mine drainage. 7. Lakes and streams. WELLS IN POTSDAM SANDSTONE Seventeen supplies from wells entering Potsdam sandstone were examined. (See Table 18.) No manganese could be detected in four- teen of them. A small amount was found in three, 0.08 part per mil- lion in water from a well at Chicago, and 0.04 part in water from wells at Riverside and Utica. These amounts are so small as to be of little significance. The content of iron ranges from 0.0 to 3.6 parts per mil- lion and dissolved solids from 278 to 5,520 parts. No relation is ap- parent between the contents of manganese, iron, and total mineral matter. Manganese apparently is not present in most water from wells drawing chiefly from Potsdam sandstone in Illinois. WELLS IN ST. PETER SANDSTONE Twenty-eight samples from wells entering St. Peter sandstone were examined. (See Table 18.) Manganese was absent from all but two of them. One of these was from a 1,300-foot well at Elgin, which furnished a water containing 0.10 part per million. As this well is 30 MANGANESE IN WATER SUPPLIES TABLE 17. CONTENT OF MANGANESE, IRON, AND DISSOLVED SOLIDS IN WATER FROM WELLS ENTERING POTSDAM SANDSTONE. [Parts per million.] Locality. County. Depth. Manganese (Mn). Iron (Fe). Dissolved solids. Aledo Feet. 3 165 00 2 078 Lee 2 400 00 1 4 450 Kane 2 000 00 4 2 198 L'elvidere Biiie Island Boone Cook 1,800 2 000 .00 00 .0 2 511 1 246 Byroii .- Carbon Hill Ogle 2,000 1 800 .00 00 .0 g 288 1 295 Chicago 8 Chicago* Cook do 2,100 1 600 .08 00 3.6 4 5,520 1 057 Dixon a Lee 1 922 00 1 301 940 00 2 278 Forest Park Minonk Cook Woodford 2,015 1 765 .00 oo .0 2 530 2 337 Morrison "Wh'teside 2 048 00 5 293 Riverside Cook 2 000 04 2 891 Utica La Salle 350 04 5 444 Waukegan Lake 1,300 .00 .1 557 Not public supply. TABLE 18. CONTENT OF MANGANESE, IRON, AND DISSOLVED SOLIDS IN WATER FROM WELLS ENTERING ST. PETER SANDSTONE. [Parts per million.] Locality. County. Depth. Manganese (Mn). Iron (Fe). Dissolved solids. Abingdon Bellwood Chad wick Knox Cook Carroll Feet. 1,350 1,400 fiflO 0.00 .00 on 0.0 1.0 1,323 546 Chenoa . . 2 100 00 i 1 1 98Q Cuba * . . . . Fulton 1 765 00 2*4.Q Elgin Do Kane do 1,300 1 300 .10 00 3.2 377 493 Peoria I Jf)A oo Fulton 1 465 00 Galesburg Genoa . Knox DeKalb 1,240 1 500 .00 00 .0 1,515 Henry Marshall 1 355 00 Ipava Fulton 1 575 00 2Q77 Jerseyville Jersey . 1 542 00 300-1 1 485 00 Lena . 600 00 4.Q7 Oregon Park Ridge Peru Ogle Cook La Salle 1,600 1,425 1 500 .00 .00 00 .8 1.0 285 820 River Forest Rochelle Roseville . Cook Ogle Warren 1,000 1,026 1 260 .03 .00 00 .1 .1 452 337 Kfifi Rockdale* Spring Valley. . . , . . Will Bureau 657 1 400 .00 00 1.4 .4 1 2,596 527 770 Sycamore . . Dekalb 905 00 O lAf) Toulon Stark 1 465 00 o 11 4.7 Warren Jo Daviess 865 00 j 070 Wyoming Stark 1,557 .00 Trace 1,047 Not city supply. cased only 100 feet and the pumps were started for the purpose of taking the sample, water from some upper stratum also may have entered the well. The other water, from a 1,000-foot well at River Forest contained very little manganese. The content of iron of these OCCURRENCE 31 supplies ranged from 0.0 to 4.0 parts per million, and dissolved solids from 285 to 2,977 parts. Manganese, then, is evidently absent from most waters in St. Peter sandstone in Illinois, and no relation appears to exist between the contents of manganese, iron, and dissolved min- eral matter. WELLS IN LIMESTONE Tests of samples from 27 wells entering limestone are given in Table 19. Manganese was found in water from wells at Flora, Marion, Matteson, and San Jose, although not more than 0.08 part per million is found in any of the waters examined. Such small amounts are without practical significance. The content of iron ranges from 0.0 to 4.8 parts per million and dissolved solids from 255 to 3,395 parts. Manganese, then, is occasionally found in small amounts in water from wells drawing chiefly from limestone, but it is usually absent. TABLE 19. CONTENT OF MANGANESE, IRON, AND DISSOLVED SOLIDS IN WATER FROM WELLS ENTERING LIMESTONE. [Parts per million.] Locality. County. Depth. Manganese (Mn). Iron (Fe). Dissolved solids. Union . . . . . Feet. 650 00 347 Harrington Carbondale Cook Jackson 325 410 .00 00 .4 1 397 2 igs Do do 610 00 4 3*395 Fairfield Wayne 200 00 4 905 Flora Clay 240 08 o 145 Forreston Highland Park 8 Lake Forest* Ogle Lake do 300 395 242 .00 .00 00 .0 .0 2 610 490 ''55 Leland La Salle 230 00 4 8 337 Libertyville Manteno . . . ~ Lake Kankakee 128 60 .00 00 I 4 712 678 Williamson 700 04 3 1 801 Do do 700 00 4 1 110 Do do 700 .04 .2 1 127 Do do 800 .05 .2 1 562 Do do 960 .06 .3 1 535 Matteson Cook Grundy 283 650 .04 00 4.0 o 713 434 Mount Morris Pecatonica Ogle 800 500 20 .00 .00 .1 .1 500 336 105 08 o 539 Steger Will 318 .00 1.0 465 Trenton Clinton . . 235 00 3 980 Villa Grove Douglas 629 .00 o 591 West Chicago North Crystal Lake. . Dupage McHenry 322 285 .00 .00 .8 .3 405 344 'Not city supply. WELLS IN UNCONSOLIDATED DEPOSITS Fifty-seven waters from wells in unconsolidated deposits were examined. (See Table 20.) The unconsolidated deposits of Illinois 32 MANGANESE IN WATER SUPPLIES TABLE 20. CONTENT OF MANGANESE, IRON, AND DISSOLVED SOLIDS IN WATER FROM WELLS IN UNCONSOLIDATED DEPOSITS. [Parts per million.] Locality. County. Depth. Manganese (Mn). Iron (Fe). Dissolved solids. Arlington Heights. . . Cook Feet. 125 00 2 751 Arthur ... Moultrie 7c 00 2 2 4.Q1 Bement Piatt 141 04 1 5 547 Bloomington McLean 100 00 1 768 Braidwood Will 20 08 3 492 Camp Point* Adams 40 12 825 Canton 8 Fulton . . 10 1 10 g 194 Carlyle* 25 2 80 26 Champaign 160 00 2 389 Chillicothe Peoria 35 00 3 504 Crystal Lake McHenry 32 00 06 444 Danville* . . 150 00 1 5 431 Do * do 150 00 4 420 Duquoin Perry . . 30 1 50 2 1 066 Edwardsville* Madison. . . 55 80 5 1 8 252 Eureka Woodford . . . 90 08 3 509 Freeport At) .20 00 ij 719 432 Gibson City Ford 55 04 I 320 Grand Ridge La Salle 196 12 8 328 Greenview Menard 80 50 1 655 Havana Mason 75 08 o 202 Henry Marshall 40 00 o 518 Morgan 30 00 1 7 515 Do do 35 00 2 424 Do do . 35 00 1 8 372 Keithsburg Lacon Mercer Marshall 35 en .16 no .3 o 1,262 400 LaHarpe Hancock 43 63 12 10 515 LaRose* Marshall 28 12 3 500 Lawrenceville* Lawrence 30 00 .0 424 Do do 15 08 1 309 Do do 30 00 1 273 Do do 11 08 2 340 Do do 13 00 1 279 Do do 20 00 1 377 Lexington McLean 115 00 1.0 400 Lovington* Moultrie . 147 08 1.3 548 Mansfield Piatt 214 04 2.1 390 Marengo . McHenry 14 04 1 392 Mount Sterling 11 53 28 3 698 Neoga 16 00 o 299 Pekin Tazewell 80 128 00 .1 465 Peoria Peoria 60 16 .0 394 Do do 60 44 .0 303 Do do 60 1.60 .1 302 Do do 60 75 8 270 Do do 60 75 6 289 Do do 90 08 .0 413 Roanoke. . Woodford 30 .06 .9 900 Rushville. . . . 20 .24 .2 362 Sheffield 50 .20 .1 505 Springfield Sangamon 45 .60 2.0 325 Staunton Macoupin 20 .12 .0 325 Tolono Champaign 140 .00 1.8 647 Urban a do 160 .00 2.0 380 Washington Tazewell 80 90 .00 2.4 367 Woodstock McHenry 85 .00 2.6 403 Not city supply. may be divided mainly into two classes; glacial drift is material de- posited by glaciers in their movement over the State; alluvium is material deposited by rivers. Carefully recorded records of the strata penetrated by wells are necessary in order to determine whether wells near large rivers are in glacial drift or in alluvium. The mineral mat- OCCURRENCE 83 ter in water from wells in alluvium may not represent exclusively mineral matter extracted from alluvium, for part or all of the water that circulates in alluvium may have entered from contiguous beds of glacial material. Few wells from which waters were examined pene- trate alluvium only, and available data regarding several wells did not permit precise classification of the materials as glacial drift in distinction from alluvium. All the wells in this group have, there- fore, been designated wells in unconsolidated deposits with distinc- tion between alluvium and glacial drift. The content of manganese of these 57 waters ranges from 0.0 to 2.8 parts per million. Twenty- two, or 39 per cent, contain more than 0.10 part per million, and 9, or 16 per cent contain 0.5 part per million or more. The results ob- tained are plotted in Figure 1. Waters from unconsolidated deposits in the eastern part of the State contain little or no manganese, those containing the large amounts are in the western part. The waters with the greatest content of manganese are near the rivers ; 10 of the 13 waters that contain more than 0.2 part per million of manganese are from wells in flood plains or terraces of rivers. The analyses of the 17 waters from wells in flood plains or terraces have been grouped in Table 21. As 12 of the 17 reveal contents of more than 0.2 part per million of manganese it seems that wells in unconsolidated deposits near rivers are more likely to contain manganese than those in uncon- solidated deposits elsewhere. TABLE 21. CONTENT OF MANGANESE, IRON, AND DISSOLVED SOLIDS IN WATER FROM WELLS IN UNCONSOLIDATED DEPOSITS NEAR RIVERS. [Parts per million.] Locality. County. Depth. River. Manga- nese (Mn). Iron (Fe). Dis- solved solids. Carlyle Clinton Feet. 25 Kaskaskia 2 8 26 Chilli cothe Peoria 35 Illinois 00 3 504 Edwardsville. . . . Madison , 55 5 1.8 252 Freeport 80 40 Pecatonica 28 .7 432 75 .08 .0 202 Keithsburg 35 Mississippi < .16 .3 1,262 Lacon Marshall 50 Illinois 00 .0 400 Peoria Peoria . 60 do 16 .0 394 Do . do . ... 60 do .44 .0 303 Do ... do 60 do ... 1.60 .1 302 Do do . 60 do .75 .8 270 Do do 60 do 75 .6 289 Do do 90 do 08 .0 413 Pulton 10 do 1.10 .6 194 Henry Marshall 40 do 00 o 518 Rushville Schuyler 20 do 24 2 362 Sangamon 45 .60 2.0 325 34 MANGANESE IN WATER SUPPLIES Figure 1. Map of Illinois showing occurrence of manganese in water from wells in unconsolidated deposits. OCCURRENCE 35 The great difference in content of manganese of water from five 60-foot wells within a few hundred feet of one another at Peoria is rather striking. The content of manganese of water from these wells ranges from 0.16 to 1.6 parts per million, and other mineral constituents also present similar differences. The percentages of manganese are shown in Table 22. Though no data concerning the normal content of manganese of unconsolidated material are avail- able the content of these samples does not seem unusual, but it may be sufficiently great to account for the occurrence of manganese in waters circulating in the deposits. No apparent relation exists be- tween the contents of manganese, iron, and total mineral matter of these waters. TABLE 22. MANGANESE IN BORINGS FROM TEST WELLS IN UNCON- SOLIDATED DEPOSITS AT PEORIA. Number of well. Depth of sample. Content of manganese. Feet. Per cent. 2 8.5 0.21 7 3.518 .30 78 5 .57 78 5 8.5 .46 78 8.519.5 .56 78 19.424.2 .31 119 5.5 .46 119 5.5 7.5 ,22 119 7.5 9 .23 119 21.6 coal .23 TABLE 23. CONTENT OF MANGANESE, IRON, AND DISSOLVED SOLIDS IN WATER FROM SPRINGS.* [Parts per million.] Locality. County. Manganese (Mn). Iron (Fe). Dissolved residue. Ashland Cass 00 1 8 490 Adams 40 1 2 876 Harrisburg Jacksonville Saline Morgan .12 00 2.3 o 281 378 Kewanee Oregon Henry Ogle. .16 00 2.4 5 541 402 Do do 00 2 449 Jefferson 7 80 51 2 1 189 Clay .00 3 4 1 272 Taylorville Morgan .00 .0 368 None of these springs is used as a public water supply. SPRINGS The 10 waters from springs that were examined show wide range in content of manganese. (See Table 23.) Six samples con- tained none, 3 contained 0.4 part per million or less, and one contained 7.8 parts per million. The water from Green Lawn Spring at Mount Vernon has a greater content of manganese than that from the spring 36 MANGANESE IN WATER SUPPLIES at Excelsior Springs, Mo., which contains 4.5 parts per million. 1 The water contains no bicarbonates or free sulphuric acid, and the iron and manganese are reported as sulphates. A surf ace water at Mount Vernon (see Table 25.) also contains 0.12 to 0.80 part per million of manganese. Water from a well at Camp Point, where the water of next greatest content of manga- nese is situated, contains 0.12 part per million of manganese. (See Table 20.) TABLE 24. CONTENT OF MANGANESE, IRON, AND DISSOLVED SOLIDS IN WATER FROM COAL MINES. [Parts per million.] Locality. County. Source. Manganese (Mn). Iron (Fe). Dissolved solids. Perry Abandoned mine. . . . 24 1 1 160 Danville Harrisburg Saline stripping mine. . . . 17.0 56 5.0 7 33Q Ladd 1 3 2 8 3-1 A A Streator. . La Salle do .... 1 4 126 5 1 379 Do do Stobb's mine 2.0 57.5 2,245 COAL-MINE DRAINAGE Coal-mine drainage usually contains iron and often large amounts of it, and such drainage is often acid because of hydrolysis of salts of iron and precipitation of iron hydroxide. The iron is derived from pyrite, marcasite, sulphide-bearing shales, and other compounds of sulphur, which are leached by water containing oxygen, and oxidized to ferrous sulphate, a compound soluble in water. Though manganese has not been considered a constituent of mine water examination of 6 samples (See Table 24) of coal-mine drainage shows that all contain manganese and that some contain large amounts. The content of manganese of one sample, which con- tained free acid when it was analyzed was 56 parts per million. All the samples of mine drainage contained large amounts of dissolved mineral matter, but none except that from Harrisburg contained free acid. No report of such large amounts of manganese in mine water has come to the writer's attention. No trace of manganese could be found even in one-gram samples of pyrite, marcasite, and shale from mines in the Streator district. A sulphide shale, which occurs with the coal in the stripping mine at Danville, where water containing 17 parts per million of manganese was found, sontained 1.10 per cent of manganese. Manganese probably is leached from minerals by mine drainage in a manner similar to the removal of iron. iMason, W. P. (1890). The manganese waters of Excelsior Springs: Chem. News, 61. 123 OCCURRENCE 37 TABLE 25. CONTENT OF MANGANESE, IRON, AND DISSOLVED SOLIDS IN WATER FROM LAKES AND STREAMS. [Parts per million.] Locality. County. Source. Manganese (Mn). Iron (Fe). Dissolved solids. Reservoir on, o 6 170 Belleville St. Glair Franklin Kohler Creek Mississippi River .... Reservoir on creek. . . . 7.5 0.02 .12 1.0 0.1 3.5 214 234 282 Cairo Alexander Ohio River .00 .1 150 Carlinville Macoupin Creek 00 j 240 317 Centralia Crooked Creek 20 j_ Chicago Danville Cook Lake Michigan ... .00 00 .0 151 309 Macon Sangamon River .02 on .1 o 454 305 East St. Louis . . . . St. Glair Effingham Mississippi River Little Wabash River . . .02 .1 .1 1 375 230 235 Cook Lake Michigan no o 158 Fort Sheridan . . do do no o 162 do do 155 Granite City Madison Mississippi River. . . . 02 1 218 Cumberland .... Embarrass River 00 05 681 Hamilton Hancock Mississippi River .... 00 o 160 Saline 00 .1 3 274 671 Highland Park Lake Lake Michigan oo 05 140 oo 1 6 1,041 Kankakee River 04 1 377 La Salle 4 00 150 2,210 Cook no Q 192 Lake do no Q 177 Lawrenceville . . Lawrence Embarrass River. . . . 02 1 575 Lowell* La Salle Vermilion River 7 50 66 1.054 2,316 Madison Madison Mississippi River .... 02 .1 224 do .... 00 1 191 Wabash Wabash River 00 1 300 Mount Vernon Reservoir 12 1 215 Do do . . .8 00 .8 1 402 155 North Chicago. . . Lake Lake Michigan 00 o 164 Oblong 8 Crawford Creek 36 1 1,353 Olney Richland Fox River 04 .7 145 Oglesby a La Salle 9 00 46 5 2,325 Pontiac do 00 05 447 Pullman ,. . . Cook . . Lake Michigan .08 00 .2 o 557 151 Quincy Adams . . Mississippi River. . . . 00 1 222 Rock Island do .02 02 J 1 250 224 Stauuton . Cahokia Creek 16 1 550 Streator La Salle 00 o 848 Venice 02 1 234 Waukegan Lake 00 o 134 West Hammond . . Cook do 00 o 146 'Not city supply. . RIVERS AND LAKES No manganese was found in any of the waters from Lake Michi- gan (See Table 25), and not more than 0.02 part was found in any of the samples from Mississippi, Ohio, Wabash, and Sangamon Rivers. Samples from Fox and Embarrass Rivers contained only small amounts. The water of Vermilion River below Streator contains 4 to 9 parts per million of manganese, and much larger amounts of iron, 38 MANGANESE IN WATER SUPPLIES as shown by analyses of samples collected at Kangley, Lowell, and Oglesby. Samples taken at Streator above the dam at the water- works contained no manganese or iron. This river below Streator is heavily polluted with mine drainage containing iron and manganese, a condition that explains the high content of manganese and iron. The presence of 0.32 part per million of manganese in the city supply of Harrisburg which is taken from Saline River, is also due. to the en- trance above the city of coal-mine drainage of high content of man- ganese. Many impounding reservoirs on small creeks in southern Illinois like the supplies at Anna, Benton, Centralia, and Mount Vernon, contain manganese. Such reservoirs are fed partly by springs, which may contribute the manganese. Their content of manganese widely varies. At Anna a variation from 0.2 to 7.5 parts per million from July, 1914 to May, 1915, was observed, and at Mount Vernon from 0.1 to 0.8 part per million during the same period. The occurrence of such amounts of manganese in surface waters nearly saturated with dissolved oxygen is contrary to past conceptions of the occur- rence of the element. In fact, much experimental work on the re- moval of manganese has been based on the theory that aeration oxi- dizes the manganous salt to an insoluble hydrated oxide, which can be removed by nitration. SUMMARY Manganese as a constituent of water supplies in the United States has been overlooked and its importance underestimated. It oc- curs normally in certain classes of water in Illinois, and amounts suf- ficient seriously to affect the quality have been found in several waters. This may be said of the water supplies at Mount Vernon, Anna, Centralia, Peoria, Springfield, Freeport, and Harrisburg. Little manganese is present in water from Potsdam sandstone, St. Peter sandstone, the overlying limestones, Lake Michigan, and the large rivers. ^ Manganese is usually present and often in very large amounts in coal-mine drainage. Manganese is present in water from some impounding reservoirs on small streams in southern Illinois, and from some wells entering unconsolidated deposits near rivers. No apparent relation exists between the content of manganese of a water and any of the other mineral constituents. METHODS OF REMOVAL 39 REMOVAL OF MANGANESE FKOM WATER SUPPLIES Methods The experimental work which has been done on the removal of manganese from water has led to the development of three practical methods aeration and filtration through sand, filtration through permutit, and filtration through pyrolusite. The problem of remov- ing manganese has been attacked by most workers in a manner similar to that of removing iron. The usual method for the removal of iron from water is by aeration followed by filtration through sand, and it is generally and successfully used in many plants in the United States and Europe. Iron occurs in most ground waters in the ferrous con- dition. When the water is aerated the iron is oxidized to the ferric condition and separates as the hydroxide. This combination of oxida- tion, hydrolysis, and precipitation is the basic principle of the method though the presence of other substances somewhat affects the results. The occurrence of manganese with iron in many waters and its sep- aration as the hydrated dioxide under certain conditions have led to the assumption that the element in water has chemical properties practically similar to those of iron. Extensive experiments on removal of manganese by this method have been conducted by Thiesing, 1 who worked with a water at Pom- merensdorf, Germany. He has concluded that manganese occurring in water as the bicarbonate can be successfully removed by aera- tion and filtration. Trickling through beds of coke or spraying through nozzles were used as methods of aeration. The removal of carbon dioxide as well as solution of oxygen was found to be important in the process of aeration. Subsequent filtration through sand gave an effluent containing very little manganese, sedimentation effected little removal. In this country extensive experiments along similar lines have been conducted by R. S. Weston 2 with several waters containing iron and manganese in Massachusetts. Mr. Weston 's problems have dealt chiefly with the removal of iron. A well water containing 0.73 part per million of iron and 0.23 part per million of manganese was treat- ed at Cohasset by being sprayed through nozzles followed by passage through a coke trickling filter and mechanical filters. Satisfactory results were obtained in the experiments and arrangements have been made for construction of a large plant. In experiments at Brookline Thiesing, [Experiments on the removal of manganese from ground water] : Mitt. kgl. Prufungsans. Wasserversorgung, 16, 210-96 (1912). ^Weston, R. S., The purification of ground waters containing iron and manganese: Trans. Am. Soc. C. E., 64, 112-81 (1909); Some recent experiences in the deferrization and demanganization of water: J. N. E. Water Works Assoc., 28, 27-59 (1914). 40 MANGANESE IN WATER SUPPLIES sprinkling through nozzles followed by passage through a coke trick- ling filter and slow sand filters decreased the content of iron from 0.6 to 0.2 part per million. The content of manganese of the untreated water was 0.26 part per million, though Weston published no figures concerning the efficiency of the removal of manganese he stated that he found it roughly proportional to that of the removal of iron. A plant for removal of iron and manganese, which has been installed at Middleboro, treats 335,000 gallons a day of water. The water, after it has been sprayed over a coke trickling filter 10 feet deep, flows into a settling basin and through slow sand filters operating at a rate of 10,000,000 gallons per acre per day. The content of iron was de- creased from 1.5 to 0.2 part per million and the content of manganese from 0.67 to 0.27 part per million during the first run from Septem- ber 26, 1913, to January 12, 1914. The efficiency of the removal of manganese increased as the plant was operated longer, and the efflu- ent on January 22 contained 0.10 part per million of manganese. Barbour 1 performed a similar series of experiments on the well- water supply of Lowell, Mass. The waters of the wells differ in con- tent of manganese, the strongest containing 2.0 parts per million. Aeration, sedimentation, and sand filtration were tried on an experi- mental scale. The efficiency of the plant was at first rather erratic, but it finally became possible to reduce the content of manganese to 0.01 part per million. A dark coloration due to precipitated oxides of manganese was observed in the sand bed, and this extended in diminishing amounts to the bottom of the bed. On the basis of this study a plant was erected at a cost of $180,000 for the removal of manganese and iron. Practically all students of removal of manganese by aeration and filtration have concluded that manganese is much more difficult to remove than iron. The details of the process, such as the amount of aeration and the rate of filtration, differ with the character of the water. The permutit process for removal of manganese has come recent- ly into the field. Permutit, the artificial zeolite 2 first produced and patented by Gans of the Prussian Geological Institute of Berlin, has come into somewhat common use in softening water. Its use for re- moving calcium and magnesium from water has been studied by 1 Barbour, F. A., Removal of carbonic acid, iron, and manganese from the Lowell (Mass.) well-water supply: Eng. Record, 70, 78-9 (1914). 2 Gans, Robert, [Manufacture of artificial zeolite in crystalline form] : U. S. pat. 914, 405, March 9, 1909, Chem. Rev. Fett-Harz-Ind., 16, 302-3 (1909). Duggan, T. R., Zeolites, natural and artificial (Abstract) : Orig. Com. 8th Intern. Congr. Appl. Chem. (Appendix), 25, 125-9 (1912). Gans, Robert. Ueber die technische Bedeutung der Permutite (der kunstlichen zeolithartigen Verbindungen) : Chem. Ind., 32, 197-200 (1909). METHODS OF REMOVAL 41 numerous investigators. Gans, however, has adapted it to the remov- al of manganese from water. The principles involved in this latter process are decidedly different from those involved in ordinary pro- cesses of softening water. Sodium permutit is made by fusing together 3 parts of kaolin, 6 parts of sand, and 12 parts of soda. The melt, after cooling, is leached with water. Gans 1 proposes the following to represent sodium per- mutit. / OH Si OH / OH \0-A1 \ :Na / OH Si OH \ OH The sodium in this compound is replaceable by other metals. For example, when a solution of a compound of calcium percolates through the crushed material, the calcium replaces the sodium in the silicate, is removed from the solution, and is in turn replaced in the water by an equivalent of sodium. On the other hand, when a solution of a a compound of sodium is filtered through the calcium permutit the calcium is forced out by the sodium. The process may be simply represented by the equilibria : ++ + Ca+2Na-permutit=2Na+ Ca-permutit. ++ + Mg+2Na-permutit=2Na+Mg-permutit. Thus, if a hard water percolates through sodium permutit, the calcium and magnesium in the water are replaced by sodium. If, after this change is complete, a solution of sodium chloride percolates through the used permutit the calcium and magnesium therein are re- placed and removed by sodium. The permutit is thus regenerated, or restored, to its original condition without loss. The series of reactions constitutes an apt application of the law of mass action. Permutit is not lost unless the water contains free carbon dioxide, which has on the permutit a solvent action that results in the formation of bicarbonate. Gans 2 noted that manganese can be removed with compounds of 1 Gans, Robert. Ueber die technische Bedeutung (der Permutite der kiinstlichen zeo- lithartigen Verbindugen) : Chem. Ind., 32, 197-200 (1909). 2 Gans, Robert, Reinigung des Trinkwassers von Mangan dutch Aluminatsilicate: Chem. Ztg., 81. 355-6 (1907). 42 MANGANESE IN WATER SUPPLIES calcium and magnesium when a manganese-bearing water is filtered through the zeolite. Usually, however, it is desired to remove only the manganese without the extra expense of softening the water. To accomplish this, Gans 1 treated permutit with a strong solution of manganous chloride or sulphate, and then with a strong solution of a permanganate. He found that if a water containing manganese or iron is filtered through this medium, the manganese and iron could be removed without the accompanying softening action. After a time the filter medium no longer effected removal, but its efficiency was re- stored by regenerating it with permanganate. The chemistry of this process is explained by Gans. 1 Treatment with manganous chlo- ride gives a manganese zeolite. 2SiO 2 A1 2 O 3 CaO-f-MnCl 2 = 2SiO 2 A1 2 O 3 MnO -}-CaCl 2 When this zeolite is treated with permanganate, the following re- actions may take place: (a) 2Si0 2 -Al 2 (V MnO a -f-CaMn 2 O 8 2SiO 2 - Al 2 Mn 2 O x +S0 3 . This is the basic reaction involved in the permutit process. The acid which is formed when the manganese is removed is undoubtedly neutralized by the alkaline silicate, for Gans 1 has shown that free acid, even carbonic acid, has a solvent action on permutit. Manganese permutit consists of a zeolite with which a layer of manganese dioxide is incorporated. When a manganese-bearing water is filtered through this medium the manganese is removed from the water by the formation of a lower oxide of manganese by reaction between the manganese in the water and the manganese dioxide in the permutit. At the same time the alkali or alkaline-earth of the silicate is replaced by the manganous compound of the water. The replace- ment is of minor importance, and the slight extent to which it takes place is dependent on the concentration of manganese in the water. Manganese is added to the permutit not only when manganese per- mutit is regenerated by potassium permanganate but also when man- ganese is removed from water by the regenerated permutit ; therefore, the content of manganese dioxide increases and the filter medium ap- proaches in composition pure manganese dioxide with each successive regeneration and reduction. As the zeolite can not increase in amount 48 MANGANESE IN WATER SUPPLIES with successive reductions and regenerations the replacement effect must become less and less as the substance is used. These conclusions are in entire accord with that reached independently by Tillmans 1 that the action of manganese permutit is realty the action of manga- nese dioxide. Sand Filtration Some preliminary experiments made by filtering an aerated arti- ficially prepared manganese-bearing water through a small sand filter showed that no removal of manganese was effected. A mechanical fil- tration plant has been installed at Mount Vernon, 111., however, for the Figure 2. Experimental sand filters for the removal of manganese. purpose of removing manganese as well as effecting hygienic purifica- tion of a surface water, and analyses of the water some months after installation of the mechanical filters showed that manganese was being removed by this plant. Manganese is also removed in a filter plant at Anna, 111., designed for hygienic purification of a surface-water sup- ply. These results seemed contradictory to the negative results ob- tained on a small scale. Yet, as manganese dioxide had been used Tillmans, J., Uber die Entmanganung von Trinkwasser: J. Gasbel., 57, 713-24 (1914). SAND FILTRATION 49 successfully for removal of manganese and as this compound is the basic part of manganese permutit it was concluded that manganese dioxide was the principal factor in the removal of manganese in suc- cessful sand filtration. Two filters were, therefore, prepared for experimental use. The apparatus (See Figure 2) consisted of two gas- washing cylinders (A, A) connected at their tops by a siphon to a large carboy (B) holding the water to be treated. The rate of filtration could be so adjusted by two stopcocks (S, S) that both niters would deliver their effluents at the same rate. A glass tube () extending to the bottom of the carboy provided means for admitting compressed air for aera- tion. Each filter was filled with one liter of clean high-grade filter sand, having an effective size of 0.50 millimeter and a uniformity co- efficient of 1.32. One filter was treated successively with solutions of manganous sulphate, sodium hydroxide, and potassium permangan- ate. After two or three treatments a thin film of black oxide of man- ganese had formed on the grains of sand. The filter was then washed with water until an effluent free from manganese was obtained. The other filter was used without such treatment. The apparatus consist- ed, therefore, of two filters working in parallel, one containing sand only, and the other containing sand which had been slightly coated with manganese dioxide. As the depth of sand in each was 35 centi- meters the filtering area of each was 28 square centimeters. The removal of manganese in a manganese-removal filter, depends on the contact of the manganous compound with man- ganese dioxide; consequently, the rate of filtration should be ex- pressed in terms of volume of water filtered per volume of fil- ter medium and not per area of filter surface. The rate varied slightly in these experiments, but it was so adjusted that a volume of water equal to the volume of the filter medium was filtered in twenty minutes. The waters used were prepared by dissolving com- pounds of iron and manganese in tap water, distilled water, and a mixture of the two. The tap water is a bicarbonate, iron-bearing water from drift wells. The determinations in Table 29 represent the character of the tap water used in reference to a discussion of re- moval of manganese. TABLE 29. CHARACTER OF TAP WATER USED IN EXPERIMENTATION ON REMOVAL OF MANGANESE. Parts per million. Turbidity 5 Color . 15 50 MANGANESE IN WATER SUPPLIES Eesidue on evaporation 370 Chloride .3 Alkalinity as CaCO 3 in presence of methyl orange 355 Free carbon dioxide 40 Iron 2.0 Manganese none Total hardness 300 Dissolved oxygen none Oxygen consumed 4.8 The first artificial water was prepared by adding 5 parts per mil- lion of manganese as MnS0 4 4H 2 to a mixture of about equal parts of tap water and distilled water. The water was aerated by blowing air through it for one hour and allowing to stand for two hours. It was then filtered through the apparatus, and manganese, iron, car- bon dioxide, dissolved oxygen, and alkalinity, were determined in samples taken at two-hour intervals. The results are shown in Table 30. TABLE 30. REMOVAL OF MANGANESE BY AERATION AND FILTRA- TION OF A MIXTURE OF TAP WATER AND DISTILLED WATER CONTAINING 5 PARTS PER MILLION OF MANGANESE. [Parts per million.] Water filtered through Sand. Sand coated with manganese dioxide. AT ST \RT 4 8 4 4 o 4 .05 o Alkalinity 200 200 196 Dissolved oxygen 7.4 7.2 6 2 Carbon dioxide 4.0 2.0 2.0 AFTER 2 HOURS ' OPERATION Manganese 4.8 4.8 o Iron .4 .05 o Alkalinity 200 200 194 Dissolved oxygen 7.2 7.4 6.6 AFTER 4 HOURS ' OPERATION Manganese 4 8 4 4 o Iron 05 o Alkalinity 200 200 194 7 4 7 4 6 6 Carbon dioxide 2.0 4.0 6.0 AFTER 6 HOURS ' OPERATION 4 8 4 05 Iron .4 05 o Alkalinity 200 200 192 Dissolved oxygen 7.5 7.5 6.8 SAND FILTRATION 51 Aeration decreased the content of free carbon dioxide to 2 to 4 parts per million, and increased the content of dissolved oxygen to 7.4 parts per million. Filtration through sand removed practically all the iron, but caused practically no change in the content of manganese, dissolved oxygen, and alkalinity. Filtration through sand coated with manganese dioxide, on the other hand, removed all manganese and iron, has decreased the content of dissolved oxygen an average of .8 part per million and the alkalinity an average of .4 part per million. These results indicate that aeration and sand nitration do not remove appreciable amounts of manganese. In the manganese-dioxide filter the manganous compound evidently combines with the manganese dioxide to form a lower oxide exactly as in the pyrolusite and the permutit processes. When manganese is removed the equivalent of free acid that is formed causes a corresponding decrease in the alkalinity. This decrease should theoretically be 10 parts per million when 5 parts per million of manganese is removed, whereas the actual decrease was only 4 parts per million. The disappearance of 0.8 part per. million of dissolved oxygen in the manganese-dioxide filter is undoubtedly due to oxidation of the lower oxide of manganese to manganese di- TABLE 31. KEMOVAL OP MANGANESE BY AERATION AND FILTRATION, OF TAP WATER CONTAINING 10 PARTS PER MILLION OF MANGANESE. [Parts per million.] Water filtered through Determinations. Unfiltered water. Sand. Sand coated with manganese dioxide. AT ST./ LET Manganese '. . . . 10.5 9.0 0.1 Iron .8 .0 .0 Alkalinity 356 354 342 5.3 3.4 5.0 4 '6 8 AFTER 2 HOURS ' OPERATION Manganese 10 10.5 .1 Iron .8 .0 .0 Alkalinity 358 356 344 5 6 4 2 4 1 Carbon dioxide 6 8 12 AFTER 4 HOURS ' OPERATION Manganese 9 5 10 o Iron 8 1 o Alkalinity 358 358 342 Dissolved oxygen 5.6 4.0 4.0 AFTER 6 HOURS ' OPERATION 10 10 o Iron 8 o o Alkalinity 356 354 340 5.7 4.5 3.5 52 MANGANESE IN WATER SUPPLIES oxide. If this were quantitative the removal of 5 parts of manga- nese should reduce the content of dissolved oxygen 1.6 parts; the actual reduction was, however, only 08 part. In another series of experiments (See Table 31) tap water in which 10 parts per million of manganese as MnS0 4 4H 2 had been dissolved was used. These results are generally similar to those in Table 30. Filtra- tion through sand removed iron, but did not detectibly decrease man- ganese. The content of dissolved oxygen was decreased throughout more than one part per million by passage through the niters, even in the experiment in which no removal of manganese apparently took place. Filtration through sand coated with manganese dioxide re- moved all manganese and iron, decreased alkalinity 14 parts per mil- lion, and decreased dissolved oxygen about the same extent to which it was decreased in the sand filter. In order to determine the effect of adding a coagulant, 2 grains per gallon of alum was added to the artificial water, the water was then aerated, and allowed to settle one hour as in the other series. The results obtained (See Table 32) indicate that little change is caused TABLE 32. REMOVAL OF MANGANESE BY AERATION AND FILTRATION, OF ARTIFICIAL WATER CONTAINING 5 PARTS PER MILLION OF MANGANESE AND 2 GRAINS PER GALLON OF ALUM. ALKALINITY BEFORE TREATMENT 356 PARTS. [Parts per million.] Determinations. Unfiltered water. Water filtered through Sand. Sand coated with manganese dioxide. AT START Manganese 5.0 .2 340 8.0 4.8 .0 340 6.5 0.0 .0 328 6.5 Iron Alkalinity AFTER 2 HOURS' OPERATION 5.0 .2 338 8.0 4.7 .0 338 7.2 .0 .0 330 6.0 Iron . Alkalinity Dissolved oxygen AFTER 4 HOURS' OPERATION 5.0 .2 340 8.0 4.8 .05 338 7.0 .0 .0 328 6.2 Iron Alkalinity Dissolved oxygen AFTER 6 HOURS' OPERATION Manganese 4.8 .2 336 7.5 5.0 .2 334 7.0 .0 .0 330 6.0 Iron Alkalinity SAND FILTRATION 53 by addition of the coagulant. Complete removal of manganese was obtained by filtration through sand coated with manganese dioxide but practically no removal by filtration through sand alone. The action in presence of both iron and manganese was studied by treating a mixture of distilled water and tap water in which 10 parts per million of manganese as MnS0 4 4H 2 and 10 parts per mil- lion of iron as FeS0 4 -(NH 4 ) 2 S0 4 6H 2 had been dissolved (See Table 33). After this water had been aerated it had a high reddish-brown turbidity caused by precipitated ferric hydroxide. Treatment of this solution by filtration through sand alone resulted in complete removal of iron but no removal of manganese. Treatment of it by filtration through sand coated with manganese dioxide, however, completely re- moved manganese and iron. The alkalinity was not decreased by pass- age through either filter ; this is not in accordance with the theory as the removal should have decreased the alkalinity by an amount equiva- lent to the manganese removed. This apparent discrepancy might be accounted for either by the presence of small amounts of substances capable of neutralizing free acid in the sand, or by oxidation of the manganous compound to a marked degree in the aeration and yet to a degree insufficient to form an insoluble compound. TABLE 33. REMOVAL OF MANGANESE BY AERATION AND FILTRATION OF A MIXTURE OF TAP WATER AND DISTILLED WATER CONTAINING 10 PARTS PER MILLION OF MANGANESE AND 10 PARTS PER MILLION OF IRON. [Parts per million.] Determinations. Unfiltered water. Water filtered through Sand. Sand coated with manganese dioxide. AT START 10.0 5.0 24 7.3 10.0 .1 26 7.4 0.0 .0 30 2.9 Alkalinity Dissolved oxygen AFTER 2 HOURS' OPERATION 9.5 4.8 24 7.6 10.0 .0 24 7.5 .0 .0 30 2.8 Alkalinity Dissolved oxygen AFTER 4 HOURS' OPERATION Manganese 9.0 5.0 7.6 10.0 .0 24 7.8 .0 .0 30 6.0 Alkalinity . ... Dissolved oxygen AFTER 6 HOURS' OPERATION Manganese 10.0 4.8 24 7.6 9.0 .0 24 7.8 .0 .0 28 7.0 Alkalinity Dissolved oxygen 54 MANGANESE IN WATER SUPPLIES Though no removal of manganese by nitration through sand could be detected by analysis the upper part of the sand became discolored by a slight deposit of manganese dioxide after the filter had been used for some time. This shows that there must have been some slight but continual removal of manganese by aeration and nitration. This slight deposit would rapidly aid in removal of more and more manganese until sufficient manganese dioxide would have been de- posited to remove completely the manganese from water filtered through it ; the process might be erroneously considered to be simply one of aeration and filtration through sand when in reality it is a catalysis by manganese dioxide. Manganese-Removal Plants in Illinois Manganese is efficiently removed from surface-water supplies by filtration through sand coated with manganese dioxide at two plants in Illinois. One of these filter plants was installed for removal of manganese as well as for hygienic purification of the water, and the other was installed for hygienic purification only, the presence of manganese in the water not being suspected. There was evidence of unsatisfactory removal of manganese for some time after the installa- tion of these plants, but efficient removal resulted after a period had elapsed for the deposition of sufficient manganese dioxide in the fil- ters. As no similar observations have been reported a descrip- tion of these two plants with some of the operating results are pre- sented. REMOVAL OF MANGANESE AT ANNA. The waterworks of Anna State Hospital, in southern Illinois, are located about 2 miles from Anna and about 3i/> miles from the hos- pital buildings. The plant was put in operation in January, 1914. About half the supply is derived from a 2,000,000-gallon impound- ing reservoir, on Kohler Creek, which is fed by springs which bubble up over the bottom of the reservoir as well as by rainfall on the water- shed. The other half of the supply used is taken from Wilson Creek, a near-by stream. Mineral analyses of these two sources of supply are given in Table 34. The supply from Wilson Creek contains practically no mangan- ese, but that from the reservoir contains a large amount. The content of manganese of water from the reservoir varies widely. Turbidity, color, and bacterial content are low compared with those of other surface waters of Illinois. The water contains much REMOVAL OF MANGANESE AT ANNA 55 TABLE 34. MINERAL ANALYSES OF THE WATER SUPPLY OF ANNA STATE HOSPITAL, OCTOBER, 1914. [Parts per million.] Wilson Creek. Reservoir. IONS Potassium (K) 5.6 4.7 Sodium (Na) . 17.8 11.8 12.6 7.5 Calcium (Ca) 78.6 43.9 Iron (Fe) 1.0 0.6 Manganese (Mn) Trace 1.4 Alumina (AbOs) 1.2 3.0 Silica (SiOj) 18.2 6.3 Nitrate (NOs) 5.3 4.0 Chloride (Cl) 3.0 1.0 Sulf ate ( SCU) 5.2 11.1 HYPOTHETICAL COMBINATIONS Potassium nitrate (KNOs) 8 6 6 5 Potassium chloride (KC1) 6 3 2 i Potassium sulfate (K2SO<) 2 4 Sodium sulfate (Na2SO4) 7 7 14 5 35 2 10 8 43 6 26 196 2 109.8 Iron carbonate (FeCOs) 2 o 1 2 Trace 2 9 1 2 3 Silica (SiOz) 18 2 6.3, Bases 2.0 0.0 Total 321.0 185.5 dissolved oxygen and very little carbon dioxide. Determinations showed 9.8 parts per million of dissolved oxygen, which is high, but only 3 parts per million of carbon dioxide when the temperature of the water was 20 . The water is treated by ordinary mechanical nitration. About one grain per gallon of alum is added, after which the water passes through a sedimentation basin affording retention for 4 hours. Calcium hypochlorite is added at the outlet of the sed- imentation basin at the rate of 0.2 part per million of available chlor- ine, after which the water passes to the niters. There are 3 concrete filter units, each having a capacity of 300,000 gallons per 24 hours. The nominal rate of filtration is 125,000,000 gallons per acre per day. The filters contain 9 inches of gravel and 30 inches of sand, which had, when it was put in place, an effective size of 0.55 millimeter and a uniformity coefficient of 1.43. The presence of manganese in a surface water containing so much dissolved oxygen was not suspected until complaint was received that the filtered water was causing unsightly stains on white plumbing fixtures and was staining fabrics in the laundry a pale yellow. A con- tent of 12 parts per million of manganese was found in the raw water July 22, 1914. Subsequent tests showed that the untreated water from the impounding reservoir contained 7.5 parts, July 30, and only 56 MANGANESE IN WATER SUPPLIES 1.4 parts, October 5. The water of Wilson Creek contained 0.05 part July 30 and a trace October 5. The effluent from the niters con- tained 0.05 part July 30 and 0.0 part October 5. The analyses of raw and filtered water indicate an efficient removal of manganese by the treatment which the water received. In order to determine the cause of this removal the plant was visited in December, 1914, and it was arranged to have determinations of manganese made regularly in the laboratory of the waterworks. It was impossible to obtain representative samples of the raw water, as the supplies from both reservoir and Wilson Creek enter the settling basin through separate inlets in such manner that thoroughly mixed samples can not be obtained until they emerge from the basin. Determinations of manganese in /the water from the reservoir were made from December 1 to February 11, and one-half of this value was taken as the true content of manganese of the raw water used. Determinations were made, however, from February 11 to May 4 on the water at the outlet of the settling basin. It was found that the content of manganese of water at this point was about half that of water from the reservoir. As the determinations were made by the persulphate method on 50-cubic centimeter samples only figures in the first decimal place are significant. The results obtained on samples from December 1 to May 4 are shown in Table 35. Manganese could be detected in the filtered water in only 7 of the 100 tests. The water applied to the filters during this period had a content of manganese of 0.0 to 1.0 part per million; the removal is, therefore, very efficient. The content of manganese of the reservoir supply has been slowly decreasing since the summer of 1914. In March and April, 1915, the content was 0.2 to 0.6 part per million, whereas in December, 1914, it was 1.0 to 2.0 parts per million. In order to determine the effect, if any, of treatment with hypochlorite on the removal of manganese the application of that chemical was omitted from May 1 to 4, 1915. As an effluent free from manganese was obtained during this period as before it seems apparent that as good results were obtained without as with bleach. The walls of the concrete filter units were covered with a layer of manganese dioxide, which in appearance resembled asphaltum paint. Samples of the filter sand were collected for examination. The sand was black although the incrustation was not sufficient greatly to increase the size of the grains. The incrustation was somewhat te- nacious, but some of it became detached when the sand was stirred with REMOVAL OP MANGANESE AT ANNA 57 TABLE 35. CONTENT OF MANGANESE OP RESERVOIR, RAW, AND FILTERED WATER AT ANNA STATE HOSPITAL. [Parts per million.] Date. Reservoir water. Raw water. Filtered 1 water. | Date. Reservoir water. Raw water. Filtered water. 1914 1915 Dec. 1 1.5 0.7 0.2 Mar. 1 .4 .2 .0 2 2.0 1.0 .2 2 .4 .1 .0 3 1.0 .5 .0 .5 .2 .2 5 1.2 .6 .1 4 .6 .4 .0 7 1.4 .7 .0 5 .4 .2 .0 9 .8 .4 .0 g .4 .2 .1 11 1.2 .6 .0 8 .6 .4 .1 13 1.4 .7 .0 9 .4 2 .0 15 1.2 .6 .0 10 .2 .0 .0 17 1.8 .9 .0 11 .2 .0 .0 19 1.9 1.0 12 .2 .0 .0 21 1.7 .8 .0 15 .4 .2 .1 23 1.1 .6 .0 16 .4 .1 .0 29 2.0 1.0 .0 17 .6 .2 .0 31 1.7 .9 .0 18 .4 .2 .0 19 .4 .1 .0 20 .5 .3 .0 22 .4 .2 .0 1915 23 .2 .1 .0 Jan. 1 1.6 .8 .0 24 .2 .1 .0 3 1.8 .9 .0 25 .2 .0 .0 5 2.1 1.0 .0 26 .4 .2 7 2.2 1.1 .0 27 .2 .0 .0 9 2.1 1.1 .0 29 .2 .1 .0 11 2.1 1.1 .0 30 .3 .2 .0 13 1.9 .9 .0 31 .3 .0 .0 15 1.8 .9 .0 17 1.7 .9 .0 1915 19 .6 .8 .0 Apr. 1 0.2 0.1 0.0 21 .6 .8 .0 2 .2 .0 .0 23 .4 .7 .0 3 .1 .0 .0 25 .4 .7 .0 5 .2 .2 .0 27 .6 .8 .0 6 .3 .1 .0 29 1.8 .9 .0 7 .3 .0 .0 31 1.9 1.0 .0 8 .3 .1 .0 9 .4 .2 .0 10 .4 .2 .0 12 .4 .1 .0 13 .3 .1 .0 1915 14 .3 .1 .0 Feb. 1 1.6 0.8 0.0 15 .4 .2 .0 3 1.4 .7 .0 16 .3 .0 .0 5 1.2 .6 .0 17 .5 .3 .0 7 1.6 .8 .0 19 .4 .0 .0 9 .8 .4 .0 20 .5 .3 .0 11 .5 .3 .0 21 .4 .2 .0 13 .4 .2 .0 22 .3 .1 .0 15 .2 .1 .0 23 .4 .2 .0 *17 .0 .0 24 .5 .3 .0 19 .0 .0 .0 26 .3 .2 .0 21 .2 1 .0 27 .4 .3 .0 23 .2 .0 .0 28 .4 .2 .0 25 .2 I .0 29 .5 .3 .0 27 .3 .1 .0 30 .3 .1 .0 1915 May 1 .3 .1 .0 3 .6 .4 .0 4 1.0 .5 .0 Heavy rains. water. The results of a soil analysis of the sand are given in Table 36. Microscopic examination of the sediment washed from the sand grains as well as of the sediment from the water used in washing the niters showed the presence of diatoms and algae, but no organisms 58 MANGANESE IN WATER SUPPLIES resembling Crenothrix were found. The material consisted chiefly of debris, such as sand, clay, and precipitated hydroxides of manganese, iron, and aluminium. TABLE 36. ANALYSIS OF FILTER SAND, ANNA STATE HOSPITAL. Insoluble in hydrochloric acid 98.25 Soluble in hydrochloric acid 1.75 Loss on ignition .91 The soluble portion consists of: Ferric oxide (Fe a O,) 16.8 Alumina (A1 2 O,) 26.5 Manganese dioxide (MnO 2 ) 12.0 Loss on ignition 54 The presence of manganese dioxide in the incrustation on the filter sand is sufficient to account for the removal of the manganese from the water. Some experiments were undertaken, however, to de- termine whether manganese dioxide was the only factor in the process. The two experimental filters, one containing sand and the other sand impregnated with manganese dioxide, which had been used in the former experimental work with artificially prepared waters, were used at Anna for filtering the raw water. The raw water contained 9.6 parts per million of dissolved oxygen and 3 parts per million of free carbon dioxide. Its temperature was 20 C. The results obtained are shown in Table 37. Complete removal of manganese was obtained when the filter containing manganese dioxide was used, but only slight removal of manganese was obtained when the filter containing sand alone was used. This filter, however, had been used for similar work previously, and a small amount of manganese dioxide that may have been present on the sand grains doubtless aided the removal. TABLE 37. REMOVAL OF MANGANESE BY FILTRATION OF RAW WATER AT ANNA STATE HOSPITAL THROUGH EXPERIMENTAL FILTERS OF SAND AND OF SAND ARTIFICIALLY COATED WITH MANGANESE DIOXIDE. [Parts per million of manganese.] Raw water. Water filtered through Sand. Sand coated with manganese dioxide. 1.0 1.0 1.0 1.0 0.8 1.0 .9 .9 0.0 .1 .0 .0 REMOVAL OF MANGANESE AT ANNA 59 In order to test the theory more completely the raw water was filtered through another pair of filters, one containing some unused sand like that with which the large filters at Anna are filled and the other containing sand from the filters which had been used nearly a year. The latter sand was coal black due to the coating of manga- nese dioxide which had formed on the grains. The results of these experiments are shown in Table 38. -Complete removal of manga- nese was obtained with the used sand, and practically no removal was obtained with the unused sand. TABLE 38. REMOVAL OF MANGANESE BY FILTRATION OF RAW WATER AT ANNA STATE HOSPITAL THROUGH EXPERIMENTAL FILTERS OF UNUSED SAND AND OF SAND AFTER USE NATURALLY COATED WITH MANGA- NESE DIOXIDE. [Parts per million of manganese.] Raw water. Water filtered through Unused sand. Used sand. 1.0 1.0 1.0 1.0 1.0 1.2 1.0 1.0 0.0 .0 .0 .0 The city of Dresden, Germany, has installed 1 a manganese-remov- al plant, in which the water is filtered through a growth of manga- nese-depositing microorganisms that remove the manganese from the water. No microorganisms of this character could be detected by microscopic examination of the filter sand and the sediment in the wash water from the plant at Anna. In order to test the possibility of their significance in the removal, however, some of the black sand which had been in use for several months and was removing the man- ganese was sterilized in the autoclave. A filter was prepared from TABLE 39. REMOVAL OF MANGANESE BY FILTRATION OF A SOLUTION OF 5 PARTS PER MILLION OF MANGANESE IN DISTILLED WATER THROUGH AN EXPERIMENTAL FILTER OF STERILIZED USED SAND. [Parts per million of manganese.] Raw water. Water filtered through- Unused sand. Used sand sterilized. 5.0 5.0 5.0 5.0 4.8 5.0 5.0 5.0 0.0 .0 .0 .0 , D., Die Entmanganung des Grundwassers im Elbtale und die fur Dresden ansgefuhrten Anlagen: J. Gasbel., 67, 944-8, 956-9 (1914). 60 MANGANESE IN WATER SUPPLIES this sterilized sand, and after it had been washed until it was free from manganese it was used to filter a solution of 5 parts per mil- lion of manganese as MnS0 4 4H 2 in distilled water. The results, in Table 39, show that complete removal of manganese was obtained by filtration through the sterilized sand. The results of these experiments prove conclusively that the de- posit of manganese dioxide on the grains of sand effects the removal of manganese. The deposit, however, has been formed gradually by the slow deposition of manganese from the manganese-bearing water assisted by direct oxidation by the dissolved oxygen. The large amount of dissolved oxygen always present in the raw water evident- ly oxidizes the lower oxide of manganese to the dioxide at the time the manganese is removed. The process is, therefore, catalytic and no regeneration is necessary. When the filter is washed the grains of sand are stirred up, and the friction probably is sufficient to scour off the coating of manganese dioxide sufficiently to prevent difficulty in operation of the plant. REMOVAL OF MANGANESE AT MOUNT VERNON Mount Vernon, a city of approximately 8,000 population, is in the central part of Jefferson County, Illinois. The water supply is TABLE 40. MINERAL ANALYSES OF THE WATER SUPPLY OF MOUNT VERNON. [Parts per million.] Casey Fork. Reservoir. IONS 7 6 8 3 Sodium (Na) 9 3 13 1 10 17 6 Calcium (Ca) ..... 13 2 23 3 Iron (Fe) 1 1 6 Manganese (Mn) Trace 1 15 Alumina (AlzOs) 2 1 Silica (SiO2) 174. 7 Nitrate (NOs) 6 2 7 Chlorine (Cl) 3 5 Sulphate (SO4) 62 1 130 8 Bases 5 4 3 8 HYPOTHETICAL COMBINATIONS Potassium nitrate (KNOs) 9 8 4 4 Potassium chloride (KCl ) 6 3 10 5 Potassium sulphate (KaSOO g 2 2 Sodium sulphate (Na2SO4) 28 7 40 Magnesium sulphate (MgS04) . .... 49 4 87 Calcium sulphate (CaSC-4) 3 5 45 8 Calcium carbonate (CaCOs) 30 5 24 5 Iron carbonate (FeCOs) 2 3.3 Manganese carbonate (MnCOs) Trace 2 3 Alumina (AhOs) 2 1 Silica (SiO2> 17 4 7.0 5 4 3.8 Total 154.1 231.8 REMOVAL OF MANGANESE AT MOUNT VERNON 61 TABLE 41. CONTENT OF MANGANESE OF RAW AND FILTERED WATER AT MOUNT VERNON. [Parts per million.] Date. Raw water. Filtered 1 water. Date. Kaw water. Filtered water. 1914 1915 Jan. 9 0.4 0.2 Feb. 16 0.4 0.0 Feb. 16 .4 .25 18 .5 .1 Mar. 24 .5 .1 20 .4 .0 July 23 .05 .05 23 .5 .0 Aug. 18 .12 .12 25 .5 .0 Oct. 14 .0 28 .4 .0 Dec. 2 .0 Mar. 2 .4 .1 5 .0 4 .4 .1 7 .0 6 .4 . .1 9 .0 15 .4 .0 11 .0 18 .4 .1 14 .6 .2 20 .3 .0 16 .6 .2 23 .3 .0 19 .7 .1 25 .3 .0 21 .7 .2 27 .3 .0 23 .8 .1 29 .3 .0 26 .6 .0 31 .2 .0 28 .6 .1 31 .6 .1 1915 Jan. 4 .6 .1 Apr. 2 .3 .1 6 .6 .1 5 .2 .0 9 .6 .0 6 .2 .0 12 .7 .1 8 .2 .0 * 13 .7 .2 10 .2 .0 15 .8 .2 12 .2 .0 18 .8 .3 13 .2 .0 22 .8 .3 16 .2 .0 23 .8 .2 17 .2 .0 25 .7 .1 22 .3 .0 27 .7 .0 24 .3 .0 29 .6 .0 Feb. 1 .6 .1 3 .6 .2 6 .6 .1 9 .4 .0 12 .4 .0 15 .4 .0 1 obtained chiefly from an impounding reservoir fed by springs in the bottom, but Casey Fork, a branch of Big Muddy River, furnishes an auxiliary supply. Water from an impounding reservoir on Casey Fork is pumped into the reservoir which is fed by springs. The mineral char- acter of these two supplies is shown by the analyses in Table 40. Both supplies have a high percentage of saturation with dissolved oxygen. The water is treated with about one-half grain per gallon of alum. After sedimentation it is treated with calcium hypochlorite at the rate of 0.2 to 0.3 part per million of available chlorine. Three concrete filters, each having a capacity of 500,000 gallons a day, oper- ate at a rate of 125,000,000 gallons per acre per day. The results of determinations of manganese made in the raw and in the filtered water from January, 1914, to April, 1915, are shown in Table 41. The determinations after December 1, 1914, were made in the laboratory of the waterworks at Mount Vernon. The content 62 MANGANESE IN WATER SUPPLIES of manganese of the untreated water varied rather widely, the range having been from 0.05 to 0.8 part per million during one year. The efficiency of removal of manganese is well shown by comparison of the contents of the raw and filtered waters. The content of manga- nese of the filtered water has ranged from 0.0 to 0.3 part per million. No manganese was found in the filtered water on 35 of the 65 days on which tests were made. The filter sand was coated with a dark colored substance, which contained a large amount of manganese. The results of the analysis of the sand are shown in Table 42. When the sand was examined microscopically before being washed no Crenothrix or similar organ- isms were found. The wash water contained clay, dirt, inert matter, diatoms, chlorophyl-bearing algae, debris, and similar material. TABLE 42. ANALYSIS OF FILTER SAND, MOUNT VERNON. Insoluble in hydrochloric acid 99.01 Soluble in hydrochloric acid 99 Loss on ignition .43 The soluble portion consists of: Ferric oxide (Fe a O 8 ) 4.8 Alumina (A1 2 O,) 27.7 Manganese dioxide (MnO 2 ) 35.0 Loss on ignition 43 The filter medium used at this plant is, therefore, similar to that used at Anna State Hospital. As the incrustation of the sand is not so great its content of manganese dioxide is somewhat smaller. This fact probably explains the somewhat lower efficiency of removal at Mount Vernon compared with that obtained at Anna State Hospital. The removal is effected, however, in exactly the same process as at the hospital, namely, by filtration through sand coated with a layer of manganese dioxide, which effects the removal. INCRUSTATION" OF WATER PIPES BY MANGANESE-BEARING WATERS The fact that water which carries only a small amount of man- ganese will cause serious incrustation of water pipes has been noted by many investigators. The incrustations consist cjhiefly of oxides of manganese and iron. Weston 1 gives analyses of three such incrusta- tions, collected from the water mains at Hanover, Germany and analyzed by him. The largest amount of manganese present was 7.15 1 Weston, R. 8., The purification of ground waters containing iron and manganese: Trans. Am. Soc. C. E., 64, 112-81 (1909). INCRUSTATION OF WATER PIPES 63 per cent. Raumer 1 found an incrustation in the water supply of Fiirth which contained 43.85 per cent of Mn 3 4 , equivalent to 10.52 per cent of manganese. The raw water contained 2 parts per million of manganese. Threadlike organisms resembling Crenothrix were found. Other examples of the clogging of pipes by manganese waters are noted by Bailey, 2 Jackson, 3 Beythien, Hempel, and Kraft, 4 Vol- mar, 5 and others. Most of these investigators attribute the deposi- tion to the growth of iron- and manganese-secreting bacteria which deposit the oxides of these metals in their sheaths. Similar incrustations, whose composition is reported by Bartow and Corson, 6 have caused serious difficulty in the water supplies of Mount Vernon and Peoria, Illinois. In a microscopic examination of these deposits no organisms resembling Crenothrix could be found. Specimens from the water mains of Mount Vernon, Peoria, Anna, and Springfield contained large amounts of iron and manganese, but none of the oxide-depositing bacteria. These incrustations, moreover, did not present the thread-like, filamentous appearance which is usually characteristic of growths of Crenothrix. In view of the important catalytic effect of manganese dioxide in processes of removal it seems probable that this substance is re- sponsible for the formation of the incrustations where organisms do not play a part. If a manganese-bearing water containing dissolved oxygen is pumped into the distribution system there is undoubtedly a very slight precipitation of manganese as the hydrated dioxide. This dioxide then reacts with the manganous compound in the water and removes it as a lower oxide. The dissolved oxygen present, how- ever, simultaneously oxidizes this lower oxide to manganese dioxide. The process is, therefore, catalytic, and is exactly the same as that occurring in the removal of manganese in a manganese-dioxide filter. As acid is formed as one of the products of reaction when manganese is removed the hydrogen-ion concentration of the water determines the point at which equilibrium is reached. Free carbon dioxide in solution renders water acid. So- a Raumer, E. von, Ueber das Auftreten von Eisen und Mangan in Wasserleitungswasser: Z. anal. Chem., 42, 590-602 (1903). 2 Bailey, E. H. S., Occurrence of manganese in a deposit found in city water pipes: J. Am. Chem. Soc., 26, 714-5 (1904). 'Jackson, D. D., The precipitation of iron, manganese, and aluminum by bacterial action: J. Soc. Chem. Ind., 21, 681-4 (1902). 4 Beythien, A., Hempel, H., and Kraft, L., Beitrage zur Kenntnis des Vorkommens von Crenothrix Polyspora in Brunnenwassern : Z. Nahr. Genussm., 7, 215-21 (1904). 5 Vollmar, D., Die Entmanganung des Grundwassers im Elbtale und die fur Dresden ausgefiihrten Anlagen: J. Gasbel., 57, 944-8, 956-9 (1914). Corson, H. P., Occurrence of manganese in the water supply and in an incrustation in the water mains at Mount Vernon, Illinois: Illinois Univ. Bull., Water-Survey Series 10, 57-65 (1913). 64 MANGANESE IN WATER SUPPLIES dium, calcium, and magnesium bicarbonates, on the other hand, render water alkaline because they are hydrolyzed. Both carbon dioxide and bicarbonate are usually present, and whether a water is acid or alkaline depends on the relative amounts of each in the solution. It is clear that the lower the content of free carbon dioxide and the higher the content of bicarbonate, the lower will be the hydrogen-ion concentra- tion, and, therefore, the greater the tendency toward precipitation of manganese. CONCLUSION The results of the researches and experimental investigations con- ducted by the writer on manganese in water and described herein are summarized in the following paragraphs. The persulphate method is the most convenient and accurate method for the colorimetric determination of manganese in water. Chloride does not interfere. Five-thousandths of a milligram of man- ganese in a volume of 50 cubic centimeters, equivalent to 0.1 part per million, can be detected. The standardized bismuthate method is accurate and reliable. The presence of chloride in amounts less than 5 milligrams does not interfere with this determination. By this method 0.01 milligram of manganese in a volume of 50 cubic centimeters, equivalent to 0.2 part per million, can be detected. The lead-peroxide method gives too low results because of reduc- tion of permanganate in using the Gooch crucible. The presence of chloride interferes in this method more seriously than in either of the others, and if more than 5 milligrams of chloride are present no man- ganese may be found even if a comparatively large amount is present. This method is at best the least sensitive of the three, and it should be rejected as a standard method. Manganese occurs normally in certain classes of water in Illinois, and amounts sufficient to affect the quality have been found in several waters. Little manganese is present in water from ' ' Potsdam ' ' sandstone, St. Peter sandstone, the overlying limestones, Lake Michigan, and the large rivers. Manganese is usually present in large amounts in coal-mine drainage, in water from some impounding reservoirs on small streams in southern Illinois, and in water from some wells entering uncon- solidated deposits near rivers. No apparent relation exists between the content of manganese of a water and any of the other mineral constituents. CONCLUSION- .-/-;..: V : **', \ ^ ] ] '-, 65 The principle underlying all processes for the removal of manganese from water supplies, except those of direct chemical pre- cipitation, is the reaction between manganous compounds and manga- nese dioxide to form a lower oxide. The removal of manganese by the permutit process takes place according to this reaction, as the state of oxidation of manganese in the substance is not greater than that in manganese dioxide. This is in agreement with the view of Tillmans. No evidence of the existence of oxides higher than Mn0 2 in this substance was found by the writer, contrary to the suggestion of Gans and the Permutit Co. No appreciable removal of manganese was obtained on an experi- mental scale by aeration and sand nitration, as reported by Thiesing, Weston, and Barbour. When an artificial coating of manganese dioxide was prepared on the grains of sand, however, complete re- moval of manganese was obtained. Manganese is efficiently removed from water supplies at Anna and Mount Vernon, Illinois, by this process, a coating of manganese dioxide having formed on the sand. If the water contains dissolved oxygen regeneration of the filter is unnecessary, and the process may be considered catalytic. The success of the aeration and sand-filtration process used by Thiesing, Weston, and Barbour is in reality due to the action of man- ganese dioxide and not to aeration and sand filtration alone. The as- sumption that manganese may be removed by the same process which removes iron is incorrect. The formation of incrustations of manganese in water pipes, where manganese-secreting bacteria are not present, is explainable by the catalytic action of manganese dioxide. VITA The writer received his early education in the public schools of Concord and Laconia, New Hampshire. He was graduated with the the degree of Bachelor of > Science from New Hampshire College in 1910. He received the degree of Master of Science from the Uni- versity of Illinois in 1912. He was assistant in chemistry from 1910 to 1911 and assistant in sanitary chemistry from 1911 to 1915 in the University of Illinois. He was chemist in the Illinois State Water Survey from 1911 to 1912 and chemist and bacteriologist of the same survey from 1912 to 1915. His publications are : With Charles L. Parsons, The solubility of barium nitrate and barium hydroxide in the presence of each other : J. Am. Chem. Soc., 32, 1383-7 (1910). With Edward Bartow, Methods of analyzing chemicals used in water purifica- tion. Proc. 111. Water-Supply Assoc., 3, 114-29 (1911). With Edward Bartow, The occurrence of manganese in the water supply and in an incrustation in the water mains at Mount Vernon, Illinois: Illinois Univ. Bull., State Water-Survey Series 10, 56-65 (1913). 66 THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. THE PENALTY WILL INCREASE TO 5O CENTS ON THE FOURTH DAY AND TO $1.OO ON THE SEVENTH DAY OVERDUE. JAM 3 J^fr m*-+ RECTD MAY Z 1 1963 LD 21-95m-7,'37 YC 21793 UNIVERSITY OF CALIFORNIA LIBRARY