HHHHHH H l l: 4:. 4; 975 , i — — fi - ‘ — —* —-'-e End \ T" m1 .1 - h“. 7*!" 7 mm -8 Ackncwledgernnt ”In“ :- "1. ' ‘ Lne «uthor teshes to express hls a rr901ation to .. qldrldee under whose huiéence ard direct;cn -4'._.' '.t - ‘ _;;L;¢tlun vus cerrled out. I~(\r!“)lt A!” 11"}fil) l) INDEX Historical Mass Action and pH Scope of Problem Laboratory Procedure Experimental Data and Curves Conclusion 15 17 20 49 H HI (1) *‘3 ORICAL Chlorine is one of the most widely distributed elements known, but it is never found in the free condition. It exists in enormous quantities in combination with potassium, calcium, and magnesium, and particularly with sodium as sodium chloride or common salt. Chlorine was discovered in 1774 by the Swedish chemist Soheele, who named it dephlogisticated muriatic acid. About 1785 Berthollet, because of the method used in the preparation of chlorine, considered it a compound of hydrochloric acid and oxygen and called it oxygenated muriatic acid. This term had previously been used by Lavoisier to describe chlorine. In 1810 Sir Humphrey Davy proved that chlorine was an element and gave it he name it bears today. The word chlorine is from the Greek word meaning green. Probably the first use to which chlorine was put was as a bleach. eres Watt first noticed that chlorine had bleaching properties. dis attempt to produce chlorine for this propose ended in failure because the chlorine had a destructive effect on fibers. This difficulty was overcome when Henry succeeded in preparing a combination with lime that could be reduced to a dry powder. The manufacture of chloride of lime wss taken up by Charles Tennant in 1799 in Scotland,1 As a disinfectant, chlorine Vs: first used about 1800 by de Yorieau, in Vrrnce, and by Criuksasnk, in England. These men didn't know whtt took place in disinfecting a substance. Yntil the middle of the 19th century disinfection was regarded as a process that arrested putrefaction. Hicro-orgsnisms were not associated with the process. In 1839 Theodor Schwann, who is regarded as the founder of the school of anti: optics reported thit "Fermertttion is arrested by tny influence cs “bl of killing fungi; specially by heat, pots ssium zrsenate, etc-----".‘3 :1 Ho '1') ’3 ID r-C H (+- (0 4 (D ’1 (D ."S n d- T (D :3 (" ”“1 3 H H 1 3 accepted because of the oelief in the theory of spontaneous gener- ation. This theory was finally refuted by Pasteur in 1862, who proved the possi oHlitr of preparing sterile culture media. a £1. One of the earliest chlorine pregrrsticns use work use an eloctrolyzed sea rater knorn as "crnite fluid. This tis introduced by H. Hermite in 1839 and res employed for domestic pur; os es and for flushing sewers and latrines. During elec rolys 0is of sea water the ragnesium chloride is partially converted into hypochlorite which dissociates into magnesium hydrate and hypochlor- ous acid. 1 Later strong salt solutions were substituted for sea in te and the product was commercially hnorn ss "Electrozore". In 1893 a plant wss installed rt Brerster, H, Y. for chlorinating severe "‘3 1 from a small group of houses with "Electrozore". The ssvaje v s dischrrosd into a s all creek r1 ich nolltted Croton Ls he. The application of "'lect rozone" proved successful. This see the first occasion on which the spec ific on; set of chl crnr ion vrs the des- . . l truction of hactsrna. The first occs sicn on vhich chlorine ccmror:n’s were used for the disinfection of water is not definitely known. As early as 1850 wells were treated with bleach, but these treatments were made without definite knowledge of the destruction of bacteria. The credit for the first sytemstic use of chlorire in water disinfection is due to A. C. Houston of Jngland. his work vzs performed at lincoln in 304-1905. Owing to flood conditions the reservors, filters and distribution system became infected with typhoid bacilli which caused a severe epidemic. The storage and purification works were treated with sodium hypochlorite containing ,1 v c o ‘ o o 1Cn availible chlorine. The dose e use one part per million of C"? ’3 chlorine. The results mere verv satisfatory.1 At the Royal Testing Station in Berlin, numerous experiments in severe chlorination were made by Kranejuhl and Furyjuivut. The results were judged by the B. coli content which was taken as the index of pathogenicity because this harmless intestinal bacillus were found to be more frequent and less viable than the majority of pathogenic organisms. E. coli is easy to test for and the E. coli index is still used in bacterial anrlysis of rate It use common European practice to use lsrge doses of chlorine, several parts per million, and then remove the excess after a predetermined contact period. Sodium bisulfite was used to remove the excess chlorine. Today water supplies are dosed to about 0.5 p.p.m. or less. The first big attempt to chlorinate on a larger scale in this country was in Chicago. In 1908 the Union Stock Yards Co. were proceeded against by the City of Chicago regarding the effluent of the Eubbly Creek filter plant. COpper sulfcte had been used in the filters but stock shippers complained that the water had a deleterious effect upon the animals consuming it. The copper treatment was eliminated and bleach substituted. The results were very satisfactory.1 About the same time Jersey City water was treated with chlorine. The ability of this process to purify water adequately was contested in court. The judge held that from all evidence the chlorine had a beneficial effect on the water and that it left no deleter- ious substance in the water. The increase in the use of chlorine was tremendous the first few years of its use. In 1908 some 50,000,000 gallons were treated a day; in 1911 over 800,000,000 gallons per day. Today the majority of plants treat with chlorine and practically all plants are equipped to do so in case of danger of pollution. Where surface water is the source of supply, chlorination is used almost with- out exception. Today most plants chlorinate with pure chlorine rather than bleach as formerly. Chlorination usually requires complicated mechanisms which need the attention of skilled operators to avoid breakdown or incorrect dosage. The dangers from the interruptions of service are so great they must be avoided by every means pos- sible. In 1916 an attendant at the water works in Yilwaukee stopped the operation of the chlorinator for 8 hours. The water was badly polluted that day, and there resulted over 50,000 cases of enteritis, over 400 cases of typhoid, and 40-50 deaths.3 The graph below shows the typhoid fever cases in Philadelphia and the effect of chlorination of the public water supply on the typhoid rate. 700 ”T I l l Ti‘ilters put irtc use 1300 600 \ Typhoid 500 Cases per 400 100,000 PCP 300 n J Chlorination started .1100 ' ' ' 0 - , 1200 1900 1910 1920 1930 Years Typhoid fever cases per 100,000 pop. from 1890, Philadelphia4 During the years 1909-10-11, when practially the whole of the city supply was filtered the average typhoid rate was 90 cases per 100,000 population, but when the water was also chlori- nated, in 1914-15-16, the rate was only 35, a reduction of 61%. MASS ACTION Lfi‘a‘i.’ AIFD pH When two substances, A and B, react with each other and there is no further change in the relative masses of the two substances, eguilibrium has been reached. When the reaction products, C and D, can react with each other to form A and B, the reaction is said to be reversible and is generally written in the form: A.+-BJ=='C +iD When equilibrium has been reached the velocity of the reaction between A and 3 is equal to that between C and D. The speed of the reactions is expressed by the Law of Kass Action, first stated by the Yorwegians Guldberg and Yezfe in 1279: "The rate of reaction between any two substances in a mixture is preportionpl to the product of the active messes of these substances in the mixture."5 In line with common practice (A) will be used to represent the concentration of the substarce A in moles per liter. Denote the velocity of the reaction from left to rirht by v—q-, then v—, cc (9.) x (3), therefore v-—e =l’l(.'\.) x r) where K1 is a proportionrlit: frotor or number, Similarly ve—<£(o) x(D), therefore ve— =1?2(c) x (:3) K2 will he a differert number from Y. Before any A and B have reacted, the corcortration of those c+ ELI‘O i the highest values, i.e., v;_.is a maximium at the hefirning of tle reaction. To C or D are *resert at the :tart, therefore ‘ , - v<-—=C at the start. is A 61:6. ‘2 react to produce C {rd .3, +- ‘x 3 concertrztions cf 1 and I decrease ard corsCQVC?tly v__+ decreases. Cn the other hsnd, v4__.strrts at zero aid increases as the con- centrations of C and D becoue greater ard greater. Finally a point of eguilibrium is reached there the two velocities are equal, i.e., v—-. = ."_. At this point or transposin , K is simply a nurber or ccrstrrt. It is the guotient of the two numbers F1 and Y?. K is called the mess action corstsnt. This general algebraic expression will he found very rseful in studying reversible reactions. Tor era gle consider the icr- izaticn of a substance like acetic acid in ctuecrs solution. A L e reaction 3: irdicated by the eeuat ., .1. This ionization is a revorsih Since this is a reversible reaction it is governed by the inis exyression states thst the constant T is egusl to the D I O O v-+ 0 hydrogen ion concentration in moles per liter, (u ), times the acetate ion ccncentrrtion in moles per liter, (CBHICe \ divided 5.9/9 by the un-ionized acetic acid in moles per liter, FKCOF;o.fl. he) ‘4 The reSpoctive unantities of the three substances will alwc vrc J‘ L. 10 be such that the above indicated quotient will always have a value numerically equal to K. The constant K which represents the above relation between the concentrations of the ions and the unionized substance is called the ionization constant. Instead of four substances - A, B, C and D - we have only three, namely, fit, CZHBOZ' and H(C2H302). This does not alter the situation: it makes a simple relation with three factors instead of four. Pure water is ionized to a very small extent according to the ionic equation H20:=: H‘ +-oH' Applying the Law of Mass Action (H‘) x (OH') _ K (H20) _ On account of its slight dissociation, any change in (H') or (OH') will have only a slight effect on the value for (H20) In fact, (H20) may be considered as a constant. If the value (H20) is designated as K1, then (m) an (art) ix or (H‘) 1 (OH') = K1 1 K = Kazo K1 KHZO equals the ion product for water. By experiment the numerical value for K320 =1 1: 10-14. If (1%") is made small then (OH') will be correspondingly larger and vice versa. In pure water, the value for (11") = (OH') =1 1 10'7 m./1. Since water is a neutral substance, it is possible to define a neutral solution as one which has a value for (H‘) or (OH')== 1 x 10'7 m./l. 11 Assume a slightly acid solution, the (H’) of which has been determined to be 1 X 10"6 m./l. Applying the equation (m x (Oh‘) = 1 x 10-14 1 x 10'14 8 = 1 x 10- m./l. -7 It follows that a solution in which (5‘) > 10 or the (ow) < 10"7 is an acid solution or gives an acid reaction. Also, a '7 is an alkaline solution in which (H‘)< 10‘7 or the (ca')> 10 solution or gives a basic reaction. It is customary, now, to use the system of expressing the acidity or alkalinity of a solution in terms of the logarithm of the reciprocol of the (H‘) and this is known as the "pH" value. Then 1 pH=='log-rH,T- Suppose the (H‘) of a solution is l X 10’3 m./l., then pH = logi—é—E? =log 10*3 = 3 The following table shows the relationship between the (H‘) and the pH values. Acid Neutral -7 (11*) 10-0-5 10'1 10-2 10-3 10—4 10-5 10"5 10 pH. 0.5 1 2 3 4 5 6 7 Alkaline (5+) 10-8 10-9 10-10 10-11 10-12 10-13 10-14 pH 8 9 10 11 12 l3 l4 Thus, an acid solution is one in which (H’)> 10'"7 or pH<~7. 12 A neutral solution is one in which (H‘) = 10'7 or pH = 7 An alkaline solution is one in which (H‘) < 10'? or pH) 7 See bibliography note 6 for source of information on mass action and pH. The pH of a solution can be determined by figuring the con- centration of the reacting substances, but in water and sewage analysis there are two other methods in common use, namely the colorimetric and electrometric methods. Colorimetric methods make use of the changes in color which certain dyes undergo under various changes in hygrogen-ion con- centration. This change in color is not complete with a very small change in pH but extends over a comparatively wide range of pH. Indicators have certain definite pH ranges for color change and the indicator selected should be governed by the pH of the sample tested. The accuraculy of the indicator is greatest near the center of its range and decreases as the limits are approached. The sample under test is compared with color standards. The follow- ing are some indicators and the pH ranges covered by them.7 Indicator . 2H Range Benzo yellow 2.4 to 4.0 Bromphenol blue 3.0 to 4.6 Bromcresol green 3.8 to 5.4 Chlorphenol red 5.2 to 6.8 Bromthymol blue 6.0 to 7.6 13 Phenol red 608 to 804 Cresol red 702 to 808 Thymol blue 8.0 to 9.6 Tolyl red 10.0 to 11.6 There are several types of electrometric pH meters. They make use of standard cells and a Wheststone bridge. Glass elec- trodes are commonly used. A Beckman electrometric pH meter was used in the control work for this thesis. 14 SCOPE OF PROBLEM The problem of chlorine stability is a direct result of ob- servations of swimming pools which formerly used hard water and more recently softened water. A few case histories are cited to give an overall picture of the problem.8 Prior to 1931 the Michigan State College pool was supplied with a pool water of 500 p.p.m. hardness and a pH of about 7.6. Liquid chlorine was added for disinfection and residuals of 0.3 to 0.5 p.p.m. were maintained. In the fall of 1931 the pool was supplied with zeolite-softened water. After several weeks of 'operation the pH drapped to 5.5 and chlorine residuals were zero. The pool water was badly contaminated. The pool was emptied and refilled with hard water. The pool operated satisfactorily as previously. In the summer of 1940, when the Moore's Park outdoor pool in Lansing was opened, a lime-soda treated water was used and a similar experience resulted. Formerly a well water of 500 p.p.m. was used. The pool was operated at a pH of 7.2 to 7.4, with a chlorine residual of 0.3 to 0.5 p.p.m. In 1940 the pool was sup- plied with lime-soda softened water with a hardness of 85 p.p.m. and a pH of 7.6 to 8.6. Vith bright sunlight the pH fell to a range of 5.5 to 3.5. To correct the pH, about 175 pounds of soda ash were added during the course of two weeks. The pH would reach 7.1 at night but drop to 5.5 during the day. A similar situation existed at the outdoor pool at Midland. 15 It was found that by adding lime the pH would remain up and chlorine residuals could be maintained. Following this experience, the Moore's Park pool was treated with 15 to 20 pounds of lime during the course of two days. The pH was raised from 5.5 to 7.6. The chlorine consumption dropped from a maximum of 12 lb. to 6 lb. per day and chlorine residuals of 0.3 to 0.5 p.p.m. were maintained throughout the day. The Richmond Park pool at Grand Rapids was examined. The water is a softened river water with a hardness of 100 p.p.m. and a pH range of 9.0 to 10.0. No difficulty is experienced in main- taining chlorine residuals in bright sunlight. The stability of the chlorine in this pool as contrasted to the other pools cited is probably due to two factors - (1) the high pH and (2) the relatively higher calcium and magnesium carbonate content of the soft water. In this investigation an attempt to duplicate this condition in the laboratory was made. It is also desired to find out the effect of pH on chlorine stability. 16 Sac} series tested in the laboratory ccnsisted of ten one- liter samples, each of different pH. Ten one-liter volumetric flasks were filled with the sample w:ter. The {H of each RfS adjusted so thtt the pH values ranged from about 3.0 to 12.0. The pH value below that of the sample was adjusted with sulfuric acid. The pH above that of the sample wrs adjusted with sodium hydroxide and lime. No attempt was made to adjust the pH to a certain value, but rather to adjust for values within the range 3 to 12. The pH values were determined with a Beckman electro- metric pH meter. Small Quantities of different types of organic matter were added to each sample in equal amounts. Organic matter used in- cluded settled sewage, peptone, activated sludge and urea. Chlo- rine in the liquid form was added in equal amounts to each sample. The same quantity of chlorine as was added to the samples was added to a liter of distilled water. This was tested for residual chlorine and this value used as the initial chlorine. The indivudual samples Were tested at 15 minutes, 4 hours and 24 hours. The starch-iodide method as outlined below was used to test for chlorine residual. l. Placed 100 ml. of the sample in an Erlenmeyer flask. 2. Added 1 ml. of concentrated hydrochloric acid (This test must be carried out in an acid medium because free iodine l7 forms compounds in an alkaline solution) 3. Added a small crystal of potassium iodide. 4. Added 1 m1. of starch indicator solution. 5. Titrated with 0.005N sodium thiosulfate solution. The reactions that take place are as follows: 2K1 -|- C12 = 21 + 2KC1 2I + 2i~Ta28203 = I‘la28405 + ZNaI Calculations: M1. 0.005N thiosulfate X 1.773:='p.p.m. Chlorine The factor 1.773 is obtained as follows; Equivalent weight of Nazszos = 158.11 Equivalent weight of I =126.92 Equivalent weight of Cl = 35.457 3. One milliliter of 0.005N Na28203 contains 0.005 x 158.11/1000 = 0.00079055 gm. or 0.79055 mg. of 112335203, ‘0. 0.79055 mg. Na25203 is equivalent to 126.92/158.ll 3‘ 0.79055- 0.6342 mg. iodine. c. 0.6342 mg. of iodine is equivalent to 35.457/126.92 x O.6342== 0.1773 mg. chlorine- Of the 1-1iter sample under test, 100 ml. was used for the chlorine determination (Step 1 above). Then 0.1773 X moo/100: 1.773 mg. of 013 per liter per m1. of 0.005N sodium thiosulfate or 1.773 p.p.m. per milliliter l8 of 0.005N sodium thiosulfate used. Therefore, ml. thiosulfate (Step 5) X 1.773 =*p.p.m. 012. The chlorine residual thus found in each sample was subtracted from the initial chlorine to find the loss in chlorine. 19 EXP 2.17%.]: II'Z‘AL Dim}. AI‘TT‘) CUTVTIS On the following pages are recorded all the results of the 29 experimental series run in the laboratory. The curves are plotted with chlorine loss as ordinate and pH as abscissa. The different types of water tested include college tap mater, zeolite and lime-soda softened waters, distilled mater and college tap lime softened. Approximately 960 titrations were preformed in this investigat- ion. The first few series were tested only once or twice during the 24 hour run. As the investigation proceeded it was believed advantageous to compile data three times for each series. he term stability is taken to mean the degree to VhiCh chlorine remains available in the solution for bactericidal purposes. 20 10 - p5 ‘ . iMixtures of Distilled Whter and College Tap NaOH ------- - No Organic Matter Added Ce(OH)2 .____; Nb. water Chemical Dosage pH Cl Chlorine ; es i .m. p.9gln p.p.gtd 39 hrs., 1 Distilled none 6.1 9.58 1.96 2 nudism: .. 7.3 8.87 1.78 3 Dist. 25% .. ~ ~ 2.03 ha '15? 4 Tap " " ' 2.65 I! N803 4'0 809 n 2031 6 ' ' 80 10.6 ' 2.49 7 " Ca(0H)2 37 8.1 ' 2.49 8 ' ' 74 8.7 " 2.31 Series 1 21 .— ,4 ‘___ .m.... -_— 'College Tap Water (350 p.p.m. Hardness) No Organic Matter Added gfim 22 No. Chemical Dosage pH #01 Chlorine Loss in p. .m. p.p.m. .p.m. 24 hrs. 1 32504 300 4.9 8.87 2.65 2 ” 200 6.1 ” 2.13 3 ' 100 6.6 " 1.6 4 none 7.3 " 2.49 5 NaOH 100 9.5 ” 2.65 6 " 200 10.9 ” 3.02 7 " 300 11.1 " 2.65 8 oa(on)z 100 7.9 ' ~ 3.19 9 " 200 8.1 ” 3.37 10 ' 300 9.4 " 3.54 Series 2 *— .W...—.-. . r e 6 v v . ,. c...— -1 tone ”03“.“. (we \ P College Tap Water (350 p.p.m. Hardness) O m C P O D. n .1. 1m . 9126 s.n 4. A. a. a. wr4 am an . . L2 66 e n .1 r. 00 .1 s q. no 4. 1. gm r no a. 4. Au hi 0 e e a. 11 11 4. A. m a...» Pen n n .8 2 H on n u p 7 60 8m a . nu n2 nu nu 5 pl 11 no 00 DP 1 a 8 c n .1 0 mm. h e» n n C P. b. e "m 11 92 a. 4. Series 4 23 pH College Tap water (350 p.p.m. Hardness) NaOH ....... 5 p.p.m. Peptone Ca(OH)2 —....... No. Chemical Dosage pHI Cl Chlorine Loss in p.p.m. p.p.m. p.243. 3 hrs. 24 hrs. 1 Héso4 300 5.0 8.16 1.6 3.55 2 ' 200 6.1 " 1.78 4.26 3 ' 100 6.6 " 1.78 5.33 4 none 7.3 " 3.12 6.74 5 NaOH 100 9.4 ~ ‘ 3.55 7.1 6 ” 200 10.8 " 2.84 6.74 7 ' 300 11.4 ' 1.95 6.03 8 Ca(OH)2 100 7.9 " 3.12 5.22 9 ' 200 8.4 " 3.2 5.39 10 ' 300 9.4 f 3.2 5.22 Series 5 24 . pH: College Tap water (350 p.p.m. Hardness) NaOH ---- No Organic Matter Added Ca(OH)2 ....... no. Chemical Dosage pH C1 _____£2h.‘l..72zina_Ia9J!l_1.n_rz.1l21m1_____1 p.p.m. p.p.nL 1 82304 300 4.9 3:4‘ 2,53 ‘ 2 ' 200 6.1 ' 1.66 3 " 100 6.6 " 1.84 4 none 7.3 " 2.2 5 N303 100 9.4 “ 2.55 6 ” , 200 10.9 " 2.55 7 " 300 11.6 " 2.47 8 ca(on)2 150 8.2 " 2.83 9 ~ 275 9.4 ~ 2.83 10 ” 400 11.3 " 2.2 Serieshé 25 10 College Tap Water (350 p.p.m. Hardness) 5 p. p .n. Peptone pfi' - Nb. Chenica1r Dosage p5: Cl Chlorine Loss in p.p.m. ' p.p.m. ~ p.p.m. 24 hrs. 1 32504 300 3.9 8.41 4.33 2 ' 200 6.0 ' 4.86 3 ' 100 6.6 ' 6.28 4 none 7.3 ' 7.17 5 NaCH 100 9.5 ' 7.35 6 ' 200 10.9 " 7.51 7 ' 300 11.7 ' 6.28 8 was); 150 8.2 - 6.81 9 ' 275 10.7 " 6.81 10 " 400 11.6 ' 6.46 Series 7 26 Distilled Inter uaon ...... Ca(0H)2 -—__. no. Che-ical Dosage pH C1 1 sheath sneaks—LU 1‘" 1 82804 50 3.2 8.4 3.08 2 ~. 10 3.9 ' 3.08 3 none 6.0 ' 2.9 4 N803 5 7.5 ' 3.44 5 ' 10 9.5 A" 4.5 6 ' 50 10.5 " 6.1 #.7 Ca(0H) 29111 8.5 ' 5.85 8 ' 24 10.2 " 7.34 9 ' 50 10.8 " 6.63 Series 8 27 6.4 6.6 6.8 pH 7.0 Mixtures of College Tap and Distilled Water No Organic Matter Added 28 ' No. Water Percent pH Cl Thlorine Loss in p.p.m. .p.m. 24 hrs. . 1 Dist. 100 8.1 8.4 4.14 L._L_Taa 2 DiBte 80 Vol . 5e45 Tan 29 3 918*- 60 7.2 - 8184 Tag; 49 ‘ Diflte 40 7.3 I! 6e98 18D 40 5 Diflte 20 7.‘ " 7e16 Tan 80 8 Diato - 7.4 ~ 7.18 Tap 100 __.._ ._ Series 9 V‘s -_..—_ ”It College Tap water (350 p.p.m. Hardness) NaOH 5 p.p.m. Peptone Ca(OH)2 ..._..__;_ No. Chemical grass 93 P‘SLMMMW 1 112804 300 4.7 7.38 1.24 2.84 4.79 2 ' 200 6.1 ' 1.51 2.93 5.14 3 “-fi 100 6.6 ' 1.86 3.37 6.2 4 none 7.3 ' 2.04 4.88 6.65 5 ' Na08_— 100 9.4 ' 2.48 5.85 6.83 6 ' 200 10.8 ' 0.88 '4.52 '6.48 ’7 ' " "’“336"")”11.s - 0.88 3.64 6.21 8 l c.(on)z 150 8.2 - 2.88 5.5 6.56 9 ' 275 10.7 " 1.33 4.88 6.65 10 ' 400 11.4 " 1.24 2.48 6.22 Series 10 - 29 lav- II .251... '. - . . . 5 _ . . . . . 4 I O O. o .s . O O O I e ,0 ' C O y . . C I C Distilled Water' 5 p.p.m. Peptene lo. Chemical Dosage ~pH Cl Chlorine Loss ig_p.p.m, ‘ p.p.m. p.p.g;_ 1; min, 4 hrs, 25 3:3. 1 8:304 50 3.2 8.9 ’1.55 246 4.56 2 " 10 3.9 ” 1.35 2.87 4.73 3 ' 2 4.7 ' 1.45 4.47 4.47 4 none 6.1 " 1.25 2.78 5.0 5 «(0282 2 7.5 n 1.45 2.42 4.29 6 " 4 8.4 ' 1.6 2.96 4.29 7 ' 10 9.4 " 2.9 3.94 6.06 8 ' 15 9.9 ' 2.6 5.35 7.75 9 ' 25 10.5 ' 1.55 3.67 7.75 10 ' 50 11.4 " 1.45 3.58 7.13 Series 11 30 O _—-,- s -a.-. Q 9 a .2! C I . Q 0 4 ,. .s .. .. -. s Q U , -- . . U I ..g - - . . I 0.. _ I I e. .. .- 4 e I 1 e. -- l I 5 ' ‘ ' O a! l s . .2n. . -.-. a s s .. - a 9 : ... - - . 1 a~ c ' I I C -. ' a. pH College Tap water (350 p.p.m. Hardness) 20 m1. Activated Sludge 31 No. Chemical Dosage pH Cl Chloride Loss in p.p.m. p.p.m. p.p.m. 15 min. _4’hrs. 21 hrs. 1 32304 300 5.1 6.3 0.15 2.66 3.81 2 ' 200 6.1 ' 0.92 2.58 3.29 3 ' 100 6.7 " 1.51 2.58 3.73 Ir~4.- 1888.- 7.4 ' 1.34 3.11 4.0 5 17.08 100 9.4 ~ 1.42 -11, 2.93 43.7.-.. 6 " 200 10.8 " 4.0 ., - -5117 "ii“i 3:7 7 8 Ca(OH)2 150 8.3 " 1.69 2.84 J‘m4.35 9 " 275 9.4 " 1.51 3.46 4.35 10 ~ 400 11.1 - 0.1 1.15 3.82 A Series 12 ~ .1 _-.—__-. .4.. C'. .7. . _ pH' College Tap water (350p.p.m. Hardness) 20 ml. Activated Sludge 32 N00 Chemical Dosage pH Cl ‘_Chlorine Loss in‘§.p.m. gp.p.m. p.p.m. 15 min. 4 Hrs. 21 hrs. 1 H2504 300 5.0 5.96 0.19 2.32 4.18 2 " 200 6.1 " 1.67 2.85 3.84 3 ' 100 6.6 " .01 3.03 4.09 4 none 7.2 ' 1.34 3:38 4.53 NaOH 100 10.3 " 1.69 3.65 4.62 6 ” 200 10.7 ' 0.36 3.38 4.80 7 7 300 11.2 ' 0.48 1.51 3.91 8 Ca(0H)2 150 7.9 ” 2.49 3.38 4.98 9 ' 275 10.1 ' 2.85 2.41 4.98 10 ” 400 11.1 " 0.19 4.18 4.27 Series 13 1 College Tap water 2 3 .4. (350 p.p.m. Egrdness) 20 m1. Settled sewage 5 1.6 2,7 _ n}! 110 fij1l‘. NaOH CE2 ....__._ N01 Chemical Dosage pH Cl Chlorine Loss in p.p.ma 4p.p.m. p.p.m 15 min. 4 hrs. 21 hrs. 1 82804 300 5.0 5.7V 0 2.48 3.53 2 " 200 6.1 " 0.44 3.287 3.81 3 " 100 6.6 " 1.95 3.46 4.34 4 none 7.3 ” 2.3 3.63 4.52 5 NaOH 20 7.9 " 2.74 4.08 4.88 6 ” 200 10.8 " 0.74 3.19 4.51 7 ” 300 11.2 " . 0.05 1.51 3.74 8 Ca(0H)2 150 8.0 " 2.48 3.81 4.70 9 ” ‘55 275 10.5 " 1.06 4.08 4.70 10 ” 400 11.3 " 0.26 1.51 2.92 Series 14 EB __-._~‘.-_. -—- "a... ”O _--“a- ”- ‘ g..."- s \ 9 ' ' e 4. . 9 2. 3 College Tap water 20 m1. setteled sewage 34 '-N3:T—Chfimical gfiosage pH 01 Chlorine Loss in p.p.m.i p.p.m. p.p.m. 15 min. _5 hrs. 24 hzg. 1 H2504 300 4.9 5.4 0 2.39 4.18 2 ' 7 200 6.0 7 0.52 4.16 4.60 3 ' 100 6.6 " 2.48 4.43 4.78 4 none 7.3 " 3.36 4.43 4.95 5 NaOH 20 7.9 ” 3.27 4.29 4.95 6 ' 200 10.8 " 70.35 3.54 4.69 7 7 300 11.2 " 0.08 1.42 3.10 8 Ca(OH)2 150 8.1 " 3.54 4.60 5.13 9 ” 275 10.4 " 2.21 4.6 5.13 10 ' 400 11.1 " 0.08 1.68 3.10 Series 15 - -4-_- a. ....-- 1 2 3 4 Red Cedar River water W—N'ST'Themic 23-2: .pH I)Cl Chlor1Ms_igrggm_ 1 H2804 300 2.9 3.4 1.54 2.78 2 " 150 4.0 " 1.41 2.69 3 ' 100 6.0 ' 0.6 2.34 4 none 7.3 ' 1.45 2.90 5 NaOH 10 8.4 " 1.27 3.01 6 ' 80 9.3 ” 0.65 3.10 7 " 150 11.2 " 0.48 2.48 ._____ 8 Ca(OH)2 100 8.7 ” 1.18 - 2.90 9 ” 150 9.4 ' 0.65 2.51 10 ” 300 11.5 " 0.04 2.16 Series 16 Red Cedar River-water pH N808 H 7———_. 08(0 )2 36 No Chemical Dosage pH Cl Chlorine Loss in p.p.m. . p.p.m. p.p.m. 15 min. 4 hrs. 21 hrs. 1 HZSQ‘ 200 3.1 9.75 4.05 9.04 9.45 2 ” 150 4.6 " 4.05 8.95 9.43 3 " 100 5.9 ” 8.75 8.55 9.31 4 none 7.2 ” 4.15 8.65 9.34 NaOH 10 8.3 ' 4.25 8.69 9.36 6 " 80 9.3 " 4.45 8.60 9.40 7 " 150 11.2 ” 3.75 8.10 9.25 8 Ca(0H)3 50 8.5 ' 4.65 8.75 9.45 9 ~ 150 9.5 ~ 4.15 8.15 9:4 10 " 300 11.4 " 3.65 7.15 9.22 '5 I Series 17 .. Ill-II I .4 8‘ III-I. . . c . . . . ll. . a. ....II.... . .f .I. I: .14 .c .9 .4 I 1... 1 o Ile- c. _ . a . . . . . . . . m .- . . u . * . n. . 4 . u n 1 . u q n e \ O 0 v w . . . . o . . . . 4' I. .9 C. . ‘0 l 4 MI .8 n .. +.u. O. h 6 . 1 . . . . 1 . _ . a . . . . e \ a c — a s . o . o . c . s . m I . . . 9 n o a 9 4 g . . . I . . — . — 4 h . . . s r u . . . — w - . . I O 1 ~ . _ . a . . _ . . . . . u a ., . .. c u . . 1 . .- l . a o . s . ~ 9 | I O 1. L. I- I h 9..) ‘7 I‘D IQ. l1ln‘.l . ~ . . o I I c Q A - e . . . I < w _ 4 O u . 1 p p n U 4 . 9 a . I . fl . . n . . . . 0 v U .I. I 0 9 4 I OI I .-.u s I. s n. In I . . H . . . . . . . J . . e e . . e e e e a .. _ . . a . 1 . l- . It [It 0 I. n L II I 0|. 4: u o . . . 0 . . . . . u . . l . . I U . ' - D s Q w. - . . . . O I . .1 .1. 4 . 4 9 e. v. .e . C # n O O . a e . e e . e e e e e 9‘ . . u . s o e 1 4 el 0 Q I O I T . Ill 5.. c ‘ . . I fie I. 4 4 -1 . . h o . . g . . . I O O O 0 O O I . 4 a s i e . n: s I I. O . I u . o 4 es .n I. o .9 u .7 L a s I! 4 e .4 . n I C . O . I e 1 . . o n a p . O O O O O O O C v 1 O . 1 . . . . . a . w . — . . a \ H . u . v . . - O . . W O _. . . .1 I. I . . e 9...e.-|'n.. '0... e . l 8818.... Added 10.6 Red Cedar River water NaOH ------- Ca(OH)2._———_. 1"N0 Chemical Dosage pH C155 Chlorine Loss in 0.p.m. p.p.m. - .- .. pflm. 15 min. m—m 1 55504 200 3.3 10.6 5.1 9.0 10.07 2 " 150 5.0 " 4.4 8.83 9.89 3 " 100 6.2 ' 4.2 7.94 9.98 4 none 7.3 " 5.0 8.74 10.12 5 NaOH 10 8.3 " 5.0 8.65 10.19 6 ” 80 9.1 " 5.2 8.92 10.16 7 " 150 11.1 " 4.84 8.04 10.16 8 Ca(OH)2 30 ' 8.7 " 5.55 9.1 10.12 9 ” 150 9.4 " 5.8 9.1 10.25 10 " 200 10.9 ' 4.84 8.12 10.05 Series 18 37 114 full U .IV Chlorine Added >;“““‘ NaOH Red Cedar River Water Ca(OH e s r .uu a. a. a. a. A. v. =5 :5 a. 6 6 6 2 5 3 4 6 6 4 or e e o o e 0 e o o e 29 9 9 9 9 9 9 9 9 9 O p . 8 Brno 8 2 8 . 8 8 4. 4 4 Ehl 0 5 3 6 4 2 2 6 6 O o e o o o e o o e e 39 9 8 7 8 8 6 9 8 7 e n 1 PC. on 1.1 . am 6 8 5 7 2 4. 3 C 7 8 6 6 9 7 7 2 0 3 5. e o e e e o o o e 14. 4. 4. 4. 4. 4. 4 5 5 4. 8 6 5 9 1 3 2 9 2 2 H o o o o o o o 0 o o p 9» 4. 5 6 8 9 0 7 9 o 1 1 0 m0 0 0 N I N N N I I I I lpo Col p 90 gm a . AU .0 Au Au AU nu .U AU AU 80.0 5 0 2 2 O 5 5 O 0.2 1 1 1 3 2 4. DD. 1 a 2. C 4 ‘1 1 0 8 H H m s n 0 0 e 2” N o a n I I...\ N N w H n N a C 0 1 2 3 4 5 6 7 8 9 m Series 19 u—. o o—v—“- -_—~~’ —.._'. l '.\\\1|| ' 10.6 Chlorine ggded 15.3 10 3 hrs. / Red Cedar River Water NaOH Ca(0H)2 ......_._ No Chemical 'Dosage pH C1 Chlorinengss;in p.p.m. p.p.m. Ap.p.m. 15 min. 3 hrs. 23 hrs. ‘___1.__§g§04 200 3.8 15.3 3.4 10.1 11.9 2 " 150 5.6 ” 3.4 8.68 13.7 3 " 100 6.3 ' 2.8 9.4 13.35 4 none 7.4 ' 3.9 9.98 14.01 5 NaOH 30 8.8 ' 4.15 10.6 14.29 6 ' 150 9.8 " 3.1 8.68 13.35 7 ' 300 11.1 " 2.7 8.27 12.55 8 Ca(OH)9 50 8.7 ” 3.97 9.45 14.24 9 ' 250 9.7 " 3.8 9.34 13.53 10 ' 400 10.8 " 3.1 8.02 13.08 Series 20 20 m . Chlorine Added 11.? NaOH College Tap (350 p.p.m. hardness) 25 m1. Settled Sewage V-NET—Chemical Dosage pH Cl Chlorine Loss in p.p.m. L; p.p.m. p.p.m. ’15 min. 34hrs. 23 hrs. 1 3250* 300 2.7“ 11.7 o 1.1 4.15 2 " 200 5.4 ' 0.1 2.6 4.88 3 none 7.3 ” 1.95 3.55 6.03 4&4 100 6.3 ~ 2.0 3.55 5.5 5 NaOH 30 8.4 ” 2.85 4.45 6.38 6 ” 100 9.4 ' 1.95 4.53 5.65 7 " 200 10.1 ” 0.4 4.1 5.7 8 Ca(0H)z 75 8. ' 2.05 4.44 6.38 9 " 250 9.0 " 3.1 4.61 6.62 10 " 500 10.fl " 1.08 3.38 6.38 Series 21 Zeolite softened (Zero hardness) NaOH -------- 25 ml. settled sewage 03(0H)2 No Chemical Dosage C1 pH ‘Jlmm in pun. mm 15 min...__4_hn.__21_hu.._n 1 H2504 300 7.0 3.9 0.1 2.3- 4.6 2 ” 200 " 5.9 1.5 4.29 5.23 3 " 100 " 6.5 3.06 4.75 5.58 4 none " 7.6 3.67 4.93 5.67 5 N303 20 " 8.7 3.72 5.0 5.76 6 " 50 " 9.3 2.12 5.05 5.76 7 " 150 ” 10.3 0.16 2.65 4.7 8 03(OH)2 50 " 8.6 3.64 5.14 5.58 ' 150 ” 9.2 2.3 5.23 6.06 1' 7 550 " 0.3L 0.88 2.3 3.86 Series 22 .191 -.o -.w- “-7- .“. O.. 0.. . n . e O. .1... e. A I I O . . . h . Zeolite softened (Zero hardness) 25 m1. settled sewage NaOH Ca(OH)2 ...__. 1 No Chem1oal 3:5:— Cl. pH 1 0:11? Wmm, __11 §2504 300 71 3.8 0.4 3.06 4.62 2 7 200 5.8 2.8 4.94 5.27 3 ~ 100 6.4 3.4 5.08 5.56 4 none 7.8 3.7 5.01 5.86 5 Neon 20 8.8 3.74 5.3 6.13 6 ~ 50 9.3 1.9 5.15 6.04 7 ~ 150 10.1 .93 4.26 5.21 8 06108)g 50 8.5 4.07 5.42 6.21 9 7 150 9.1 3.0 5.77 6.48 1L10 ~ 550 10.0 1.16 3.15 5.06 Series 23 1 Lime-Soda Softened (Lansing Plant) (85 p.p.m. Hardness) NaOH Settled Sewage F-fi5F_Ehemical Dosage Cl pH . thgzigg_Lg§§ in ‘.p.m. p.p.m. .p.m 15 min. 4 hrs. 4m..— 1 H2804 100 8.47 2.8 0.27 1.73 4.06 2 ” 50 ” 3.5 0.43 1.73 4.22 3 ” 20 ” 6.5 0.67 2.45 4.75 4 none " 9.3 1.57 3.24 4.93 5 NaOH 10 " 10.1 0.43 3.24 4.22 6 ” 20 " 10.3 0.67 2.80 4.67 7 ” 50 ' 10.8 0.13 1.92 4.29 3 °‘(°H)2 25 ~ 10.1 0.41 3.24 4.67 9 ” 50 " 10.2 0.57 3.07 4.83 0 ' 100 " 110.6 0.4 2.45 4.75 Series 24 """T‘" . Lime-Soda Softened (Lansing Plant) (85 p.p.m. Hardness) Settled Sewage NaOH 44 N0 Chemical Dosage CleH Chloriég_§oss in njp.m. p.p.m. p.p. 15 min. _4 hrs. 23 hrs. 1 82804 60 7.26 3.25 0 2.66 4.41 2 ' 40 " 4.3 0 2.83 4.46 3 ” 15 " 7.3 0.79 3.45 4.66 4 none " 9.5 0.59 3.54 4.42 5 neon 5 " 9.8 0.38 3.8 4.6 6 " 20 " 10.5 0.06 1.66 4.78 7 ~ 60 n 10.9 0 1.5 3.54 8 Ca(0H)2 15 ' 9.9 0.71 3.72 4.6 9 " 70 " 10.5 0.53 2.11 4.25 _;Q " 150 ' 10.9 0.16 1.14 3.36 Series 25 w; ._ _ _,V‘_; ‘7 — _ h -- 7 c . ‘ C 0 4 ,. n e e a . ' ~ I 0 1 I 1. 4 5 7 - o 4 I , '1 C . O ‘ . . r - . a O n 5 O O ‘ I ° I . . Q . . 7 e . . O - O a" College Tap water (Lime-Softened to 110 p.p.m.) 25 m1. Settled Sewage . NaOH ------- 45 N04 Chemical Dosage pH C1 Chlorine Loss in p.pTfiT-"“ p.p.m. p.p.m. 15 min. 4 hrs. 22 A . 1 HéSO4 100 3.5 6.2 0.17 1.95 3.27 ’2 " 70 6.3 ' 2.39 4.96 5.4 3 ' 65 6.7 ” 3.19 5.32 5.56 4 ” 50 8.8 " 4.16 5.58 5.76 5 ” 25 9.9 " 0.44 3.19 4.25 6 none 10.5 " 0 1.33 3.9 7 NaOH 30 10.8 ” 0 1.59 3.72 8 ' 100 11.1 ” 0.25 1.24 3.1 9 Ca(OH)2 100 10.9 " 0.7 1.5 2.66 10 ' 300 11.1 ' 0.53 1.68 3.37 Series 26 I...- '16 _ pf] College Tap water (350 p.p.m. Hardness) 5 p.p.m. Urea N0. Chemical 3:: pH hgmfi 15 711“.an m 1 35304 300 3.4 7.62 . 0.08 0.62 1.23 2 ' 200 5.7 ” 0.17 3.45 6.82 3 ' . 100 6.3 . ' 0.36 5.76 7.09 4 none 7.1 ' 0.44 2.12 4.52 5 N805 30 8.1 " 0.97 3.9 6.11 6 ' 100 9.1 ” 0.97 3.01 5.04 7 ' 200 9.8 ' 0.52 2.3 4.52 8 Ca(OH)2 75 8.4 ~ 0.97 3.01 5.22 9 ' 350 9.3 ' 1.06 2.39 4.52 10 " ' 500 10.6 ' 0.35 1.6 3.9 Series 27 Wm— «Mm A “*- 0 I e o , O C . . o a. . . ‘ ' D . D O O . I a C o 1 O 3 4... pH' Zeolite Softened (0 Hardness) NaOH - ...... 5 p.p.m. Urea Ca(OH) ............. No. Chemical Dosage pH Cl Chlorine Loss in '0. pm. p.p.m. p.p.m. 15 Mine 4 hrs. 21 hrBe 1 32804 300 4.6 7.1 0 1.17 2.75 2 " 200 5.6 ” 0 4.88 6.83 3 ' 100 6.3 " 0 6.39 6.83 ' 4 DODQ 7e3 n Oel 3e02 4062 5 NaOH 20 803 7 105 4062 5e86 6 ' 100 9.2 " 1.6 4.79 6.12 #5 7 " 200 10.0 " 1.78 3.38 5.06 i 8 08(0H)2 50 805 n 009 302 5006 9 " 200 9.4 ' 0.2 1.78 3.83 10 ' 600 10.4 ' 0 1.6 3.91 Series 28 47 . ‘ w ‘ l I l 9 v o -uh-h “F' (85 p.p.m. Hordness) 10 11 Lime-sods Softened Nagy ...... 5 p.p.m. Urea Ca(OH)2 _____ 33:23 pH .33. 12:23:. 4 ,3: ' 22m 1 H2804 so 3.1 8.5 0.35 1.4 2.92 2 " 15 6.7 " 0 3.98 7.7 3 ” 8 8.1 " 0.26 3.62 7.79 4 none '9.3 " 0.26 2.1 5.04 5 NaOH 10 9.9 " 1.15 3.54 5.84 6 " 20 10.2 ” 1.05 2.82 5.66 7 " 50 10.6 ' 0.35 1.76 4.24 s Ca(OH)2 20 10.0 n 1.15 2.92 5.34 9 ” 50 10.4 " 1.05 2.73 4.95 10 ” 150 10.9 ” 1.67 2.3 4.69 Series 29 48 CONCLUSION An interpretation of each series will be presented and then a general conclusion. Series 1 - Series 2 - Series 3 - Series 4 - Tap water - No organic matter added. The curve is fairly straight; there are no marked changes. Tap water - Ho organic matter added. The greatest stability is at pH 6.6. Chlorine activity increases until pH 10 where it drops off. Lime causes greater chlorine loss than NaOH. Omitted because pH's were not checked. Peptone in tap water without adjustment of pH. Indicates that with increase of organic matter there is an increase in chlorine loss. Series 5,6,7 - Tap water- Peptone added. Series 8 - Series 9 - The chlorine is more stable at low pH and is suc- cessively less stable as the pH increases until about pH 9 to 10, after which a greater residual is maintained. Lime solution offers greater chlorine stability than NaOH. Distilled water Chlorine stability decreases as the pH increases up to pH 10.2 at which point stability increases. Nixtures of tap and distilled. 49 As in series 8, there is increasing chlorine loss with increase in pH. Series 10 - Tap water and peptone In this series chlorine residuals were run three times during the 24-hour period. Chlorine loss increases as the pH increases up to pH 9.4, after which a decrease is noted. The greatest chlorine loss in the 15-minute run was at pH 7.3. Series 11 - Distilled water and peptone Chlorine activity is low at low pH and increases with greater pH up to nH 9.9 after which point the chlorine becomes more stable. Series 12,13 - Tap water and activated sludge Chlorine loss increases as the pH increases up to about pH 9.4. The critical point was not located in series 13 because no sample was adjusted to a pH: between 8 and 10. Chlorine stability is about equal in lime and NaOH solutions. Series 14,15,21 - Tap water and settled sewage As with peptone chlorine stability decreases as pH increases to a pH of about 9, after which chlo- rine becomes more stable. The critical point was not reached in 14 and 15, but in series 21 there were several pH values near the critical point. Lime and NaOH solutions follow similar patterns. The greatest chlorine loss occurs in the 15 minutes. 50 Series 16,17,18,19,30 - fled Cedar River rater There is not quite the marked change in river water as in other samples. Chlorine loss was con- siderable over the whole pH range. ituhility did increase between pH 6 and 7, and then ayzin rt values greater than 8.5. Series 22,23 - Zeolite-softened and settled sewage This water shows marked changes, with good chlorine stability at low pH and decreasing stability with increasing pH up to 9 to 9.5. The critical point is at pH 8.5 for the 15 minute runs. Series 24,25 - Lime-soda softened water and settled sewage This water shows successively less chlorine stabil- ity with increasing pH up to pH 9.5 to 10.0 after which greater stability is indicated. The curve is not so marked as college tap and zeolite soft- ened. There is considerable loss in the lower pH range. Series 26 - Tap water, lime-softened and settled sewage There is a marked change here with increasing chlorine loss of the pH increases up to pH 8.8 after which the loss drOps very rapidly. Series 27 - Tap water and urea Series 28 - Zeolite softened and urea Series 29 - Lime-soda softened and urea These three samples show increasing chlorine loss up 51 to pH 6.5 at which point there is less loss up to 7.0 - 7.5 in 27 and 28, and 9.3 in 29. Then the curves swing up as in all previous samples until pH 8 to 9 in 27 and 28, and 10.0 in 29, after which stability increases. Little loss is experienced in 15 minutes. General Conclusions; In all samples tested (except those with urea where two critical points occured) chlorine is increasingly less stable until pH 8.5 to 10 after which stability increases. Not much difference was noted between lime and NaOH solutions as concerns chlorine stability. The ammonia radical in the different organic matter used is probably responsible for the loss of chlorine. Chlorine combines with ammonia to form chloramines. The test results indicate that these combinations take place more readily at certain pH's. Some chemical combinations take place within a very narrow pH range, but whether this is true in this case is not known. The action of chlorine in swimming pools was not duplicated in the laboratory. Both hard and soft waters showed similar tendencies in the laboratory as concerns chlorine stability. The use of lime in swimming pools to increase chlorine stability did increase stability in the test samples, but the pH was higher in the test samples than in the pools. Suggested further study: In any future investigation of this type it would be well to 52 work within narrower pH limits, 1.6., 6.5 to 10.0. Tests for ammonia should be made since indications are that ammonia is a big factor. Also, pH values should be checked at time of test to determine if there is a drOp in pH. 53 1. 2. 3. 4. 5. 6. 7. 8. BIBLIOGRAPHY Race, Joseph "Chlorination of Water," pp. 1-13, John Wiley and Sons, Inc., 1918 Schwann, Theodor (quoted in (1) from the German publication "Microshopische hntersuchungen.when die hbereinstimmung in der Testur und den wachstum der Tiere und Pflanzen" Berlin, 1839) Hansen, Paul, "Proc. Lake Michigan Sanitation Cong.”, p. 17, July, 1927 Steel, Ernest‘W., "Water Supply and Sewerage," p. 3, McGraw- Hill Book Company, Inc., 1938 Kolthoff and Sandell, "Textbook of Quantitative Inorganic Analysis," p. 33. The Macflillan Co., 1936 Long and Anderson, "Chemical Calculations," pp. 209-219, McGraw-Hill Book Company, Inc., 1932 Theroux, Eldridge and Mallmann, "Analysis of Water and Sewage", p. 31, McGraw-Hill Book Company, Inc., 1934 Filler, Mallmann, and Devereux, "Stabilization of Chlorine in Water”, American Journal of Public Health, Vol. 32, No. 9, September 1942 54 A) n .3 '49 Nm MICHIGQN STQTE UNIV. LIBRQRIES ‘H HEN ‘M \W \‘\|H|,‘1\\\‘1|‘1‘.|‘, \|'\ WI H W W ‘« »| 61726 312935002