I

I

AN INVTESTIGATION OF THE METHODS USED IN THEDETERMIN„ATI€2V OF THE CHLORINE DEMAND OF

SETTLED SEWAGE

YUCharles Edward Williams

Thesis sutmitted to the Graduate Faculty of the

Virginia Polytechnic Institute

in eandidacy for the degree of

MASTER W SCIENCE I

inSanitary Engineering

APPROVED: APPROVED:

Director of Graduate Studies Head of Department

‘ ’" “"“‘°" — ,e ~i" ° "V , _ 'o L-¤···ü"erin Fhjor Professor ·

Blacksburg, VirginiaAwu, 1952

P

jéogbf Ii

-2...

TABLE W CONTENTSPaea

I. INTRODUGTIM.................. 7

II.REVIEMOI·‘LI'I'ERATUR;E:.............. 9III.TI·EINVESTIGATIG¤................ ll

Thoorya11dApperotus............ 11

StarchIodideb¢ethodc......... 11

Acid {ktho Tolidiue Method . . . . . . 12

AmpercmetricMethod¤......... 14

Sampllng........ ......... 17P1·ooedurc................. 18

I Method oI‘Ch1orir1etio¤ . . . . . . . . 18Neutral Storch Iodide Method . . . . . 19

Acid Storch Iodide Method. . . . . . . 20

Acid Ortho Tolidiue Method . . . . . . 20

Neutral Amperemetric Method. . . . . . 20

Acid Amperometric Method. . . . . . . 214 Storch Amperometric Method . . . . . . 21

Rcsults..•.•.....•....... 22IV.DISCUSSIONOFRESULTS....•......... 38

Neutral and Acid Storch IodidoGh1o1·i¤cDe1uands.••••...••.. 38

..3..

TABLE OF Cm1TEN'1°S (Gcntinued)Page

Neutral Starch Icdide and Neutral

Ampercmetric Chlorine Demaxxds • • • • • • 40

Acid Starch Iodide and Neutral AmpercmetrioChlcrineDema11da••••••••••.. 41

Acid Ortho Tolidinc and Neutral Ampere-

metr1.oChlcrineDemands..••„•••• • A2

Acid Orthc Tolidiue and Acid Ampcrcmetric

Ch1c:·ineDema¤de.•„••„.•....• 43

Neutral and Acid Ampermetric ChlcrineDemands••••••••„••••„••• M

Neutral end Starch Ampercmctric Methode. • • L5

v. cormmexous................... 4749

VII.BIBLIOGRAPI1Y.•••••••••••••••••• 50

Literature0ited•••••••••.•••• 50

Lite1·atureE:mmsined..•••••••••• 51VIII.VITA.•••••••••••••••••...„ 5l+

IX•APPmIDICES.••••••••••••••„•„„ 55

Ne« ir

.4.

LIST GF FIGURES

Figure Page

1 Amperomatrie Titrater (Left) and Ortho

·1·¤11«11aa caapaeator (Right) 13

2 Sampling Station at the Primary Glarifier

Effluent ef the V, P, I, Treatment Plant. 16

3 Neutral and Acid Starch Iedide Ghlerine

Demanda................. 25

1, Neutral Starch lodide and Neutral Ampere-

reetricChlez·:Lnel)emanda......... 27

5 Acid Starch Iodide and Neutral Ampere-

metricühlerinebamands. . . . . . . . . 30

6 Acid Ortho Telidine and Neutral Ampere-

met1·icG'bleri¤eDemands.• .... . . . 32

'7 Acid Qrtho Telidine and Acid Amperemetrie

Gh1eri¤eDemaude............ BL

8 Neutral and Acid Amperemetric Chlerine ·

Demanda.... .. .......... 36

9 Gccrrelatien cf Chlcrine Demand Methods Based

cn the Neutral Ampercmatric Chlea··i·eeDemands.•.••••••..•••••• 39

A — ri

a

..5. ‘

IJST OF TABLES

Table Page

l Neutral and Acid Starch Iodide ChlcriueDcma-¤d••••••••••••„••••„„• 23

2 Oerrelatiom cf Neutral and Acid Starck

Iedide Chlorine Demauds• „ • • • • • . „ • „ • 24

3 Neutral Starch Icdide and Neutral Ampercmetric

Chlor:LueDemauda..•••••.••••••. 26Z, Acid Starch Icdide and Neutral Amperemetric

ChloriueDemax1ds„„••••••••••••• 28

5 Correlatiou of Acid Starch Iedide and Neutral

Amperemetrie Chloriue Demauda, . • • • • • • • 29

6 Acid Ortho Tclidine and Neutral Amperometric0blorineDema11da„•••••••••„•••• 31

7 Acid Grthe Tolidlne and Acid Ampercmetric

ChlorineDemauda•••••••••••„„•• 33

8 Neutral and Acid Amperemetric Chlorine Demandm • 35

9 Neutral and Starch Ampermnetric ChloriueDemauds••••••••••••••••••• 37

10 Ccrrelatiou cf Neutral Starch Iodide and

Neutral Ampermetric Ghlorine Demanda • • • • 58

ll Correlaticu of Acid Crthc Tolidiae and

Neutral Ampercmatric Chlorine Demaxxdc • • • . • 59

VA •

W u-6-

LIST TABL% (Ccmtinued)

Table Page

12 Gorralation of Acid Orthc Tolidine and Acid

Ampercmetric Ch1o1•:1.x1e Demanda . • • • • • • • . 60

13 Gorrelatieu of Neutral and Acid Amperemetric

Gh1.orineDa:2xandS••••••• „••••••• 61

‘ ‘

..7.

I, INTRODUCTION

Chlorine is used in the treatment of sewaga mainly topreventan

increase in ths bacteria populatiom, thereby protactimg the ra-

caiving water frcm coutaminatiun. It is also used to solva special

problems im the sawaga treatment system, such aa controlling odcrs

in the Sever lines and im the sawagu treatment System; controlling

trickliug filter flies amd trickliug filter foamiug; controlling

digaster foamiugg and raducing the B, 0. D, of the scwage. Ghloriua

may ba applied to Savage hy one am a ccmbimatiom of the fclloing

methods: in the sewar linßs bafcra the sawage reaches the aewaga

treatment plant (Up-sauer chlorination); 1¤.the iufluant to the

sawaga treatment plant (Pr6—chl¤ri¤at1¤n); in the offluant to the

sawaga treatment plant (Pbst«ch1¤rimatio¤); and at points within the

sewage treatment plant (P1a¤t—chl¤rinati¤m).

The amuunt of chlorine required dspends upon the type of sewaga

treated and the degree of treatment given the sewage, whsreiu enough

must ba addßd to satisfy the demand of the organic material present

in the aawage. When this demand has been satiafied, further addi•

tie will cause a reaidual chloriue content te bs present in the

sawage, Tha chlorine demand is defißd as the amnut of chlorine that

is required to ba added as ohlorinc water to satisfy the needs of all

the ccmpaunds in ths sawaga and still have a 0,10 pp. raaidual at

the end af a fiftaau minute coutaßt périod (2)• Discrepaucias in the

MMM-8-

results obteined by the various methods employed in the determine-

ticm ef chlorine residuals effers the possibility of either too

little er too much ehleriue used in sewsgeehleriuation.This

investigation ef the methods used in the determinatim

of the chlerine demand was mda in an effort to determine the

oorrelation which exists between the chlerine demand determine-

tion methods in settled seweg¤e„

"" FII. REVIHJ GF LITSRATURE k

IThe starch iodide method was the original chloriue

residualdeterminationtest (L); however, the ende-point was difficult to Edistinguish due to the absorpticm of the free iodine hy the sewage Econstituenta (7) and (8), The crtho tolidine method was developed

i(to eliminate this difficulty. This reagent will pmroduoe false end- ~points due to the presenoo of nitrites, manganese, or ferrio iron

. in the sewage (2) and (4)} however, W acidifying and W plaoing the

sample in the dark during color development, this interference may

be eliminated, Since the addition of acid to the ortho tolidine

induoed errors in the results obtained, the amperometric titrator

was developed (6) , Several variations of the amperometric titrator

have been developed: Barks, Joiner, and Strandskov (8) developed

the neutral amperometrio method; Marks end Joiner (7) developed the

acid amperometrie method; and Strandskov, Marks, and Horchler (10)

developed the starch emperometrie method,

Marks, Joiner, and Strandskov (8) reported that the acid ß

ortho tolidine and the neutral amperonzetric methods gave results

which varied widely from sample to sample. Strandskov, Fhrks, and

Horchler (10) found that a zero reading with acid ortho tolidine

was obtained on a large number of chlocrinated effluent samples which

gave neutral amperometric residuals as high as 1.00 ppm. Heukelekian Eand Day (5) found a correlation between the acid orthe tolidine and

”é%”Ü-10— I

neutral amperoetric methode using the method of least quaree,

wherein 1,2 to 1,6 ppm, ampeometrio residuala were required tc

produoe a measureahle ortho tolidine reaidual and the rate of

inerease·was 2,00 pm. amperometric residual fo each ppm. in-

crease in the ortho tolidine residue1• Mrke and Joiner (7)

reported that the acid amperetric reaiduala were comparable

with the acid ortho tolidine residuals,

Huebaum and ueyarae (9): using the spot taat to determine

chlorine reeiduale by the p—aminodimethyl, neutral and acid ortho

tolidine, and neutral and acid atarch iodide methode, found good

agreement between p·emincdimeth1, neutral ortho tclidine, and

acid atarch iodide methode; however, the acid ortho tolidine and‘

neutral staroh iodide methode did not have any relation to one

another except that the chlerine demand was much higher than that

of the other methode, Good agreement was obtained between the acid

etarch iodide and the neutral ampercetric methode.

II

. ··”···

III. THE INVESTIGATIN

When sewage is chlorinated at a neutral pH, sufficient chlorine

(HOCl) must be added to react with the sewage censtituents (X) other

than the amnonia and complexed organie compounds -HOG1 4 X —-•—-—

Futher addition of chlorine will cause chlorine residnals in

the fern of chloramines to be present in the eewage -HOCI 4 NH3 ~———-—- Nüéül 4 HUHn0¤1&mm2-—-•mmc1+a0H

These chlorine residuals are formed hy the reactien of the

chlorine with ammonia and cemplexed organic empounds. The chlo-

rine demand determination methode used in this investigation indicate

the amount of combined ehlorine residnal pesent in chlorinated

sewage,

ätgggh Iggigg yethoggz The felloing equations illustrate the

reactions which take place in determinatien of the ehlorine demand

of sewage hy the starch iodide method:

2KI 4 C12 -——- ZKC1 4 I2

I2 + 2Re2S203 —-—— HaQS4p6 + 2NaIIII

11 1

11·l2- 1

Potassium iodide (KI) combines with the combined forms of chlorine

to liberate free iodine which upon addition of starch solution

forms the characteristio blue color, providing a chlorine residual

is present in the chlorinated eewage sample, Titration with sodium

%hi0S¤lfä$@ (Nazägg) causee the blue color to disappear when all

the free iodine has reacted.with the sodium thiosulfate,

gg;d‘Qg§hg Toligdne thgds The following equation illustratee

the reaction which takes plac in the determination of the chlorine

deand by the acid ortho tolidine method (3):

H HH H ' '°

• H - N -<;]> -•<[Q> - N - H2H’—·<;)·-(Ä? -·H 4 C12 - -- I GH? CH3 :H CH3 GHB H1

1 1 1\11 cw} 01613 11 C1

Hhen the pH is above 1,8, acid ortho tolidine plus the free and

combined forms of chlorine react to form meriquinone of ortho

tolidine due to the onidatio of the ortho tolidine by the chlorine,

Pro a pH of 2,0 to over 6,0, chlorinated ortho tolidine appears tc

be a fairly good pH indiator (3), As the concentration of the

total chlorine inoreaees, the color developed by the meriquinone_

of ortho tolidine inoreases and standard color dieks have been

developed to determine the concentration of the total chlorine

.lg„

present on this basis, Nitrites, ferric iron, and manganese also

form with ortho tolidine the colors characteristic cf chlorine and

otho telidine,

A Hellas and Tiernan turbidity compensating comparator

(Figure 1) was used to determine the ehlorine residual present

in the chlorinated sewage sample, This instrument consists of a

standardized color disk, two sample tubes, and an eye piece, A

comparison is made of the reaction of ortho tolidine and chlorine

with that of the standard color disk,

Agpggggtgég ggthodss The following equatios illustrate the

reactions which take place in the determination of the chlorine

demand hy the amperometric methods (1):

2KL 4 G12 -——— 2KCl 4 I2G6H5ASO 4 I2 + HOH •-·--·- C6H5AS(0H)2 4. 2111

Phenylarseneoxide reacts with either free ehlorine or free icdine;

however, it will not reset with the combined forms of chlorine,

Potassium iodide is added to liberate iodine from the combined

forms of chlorine (1), when using this method in sewage determine-

tios, a process of “baek-titration" is omployed• Potaseium iodide

is added to liberate iodine from the combined forms of chlorine

which in turn reacts with the phenylarseneoxide• Since an excess

of phenlarseneoxide is added to the sample, the remaining unreact—

ed phenylarseneoxide mmst be titrated with free iodine; hence the

VV

I I.1§„

_ term “back~titration", Just before back•titrating with the iodine,

the pH is lowered, by the addition of HC1, to approximately 2.5.”when two electrodes are plaoed in contact with a solution

and an electrical voltage is impressed, the current can flow only

if the voltage is sufficient to cause a chemical reaction at both

olectrodes. The chemical reacticn at the positive electrode is

oxidation; that at the negative electrode is reduction. Current

can flow only if oxidation occurs at the positive electrode andreducticn occurs at the negative electrode, with a given impreseed

voltage, these reacticns are possible and, if the proper reducing

agent is in contact with the positive electrode and if the proper

oxidizing agent is in contact with the negative electrode. In the

determination of an oxidising agent, such as chlorine, a large

easily oxidiaed positive electrode is used. Under proper conditions,

the current that can flow will depend nly·upon the concentraticn

of the cxidizing agent which is reduced at the negative electrode (6)."

The solution is agitated to increase the sensitivity of the negative

electrode.

A.wallaee and Tiernan Ampercetric titrator was used (Figure l),

which consisted of a displacement cup, ampermetric titrator (con»

sisting of a microammeter, burrette, porous cylinder, agitotor cup,

and sample jar), and reagent bottle.

r

.17.

Thea modifications of the amperometric titrator were used in

this investigation which are explained hiefly below, The neutral

and acid amperometric methods used the same reagents; however, the

difference was tTe order in which the reagents were added to the

chlorinated sewage sample, In the neutral amperometric method,

the phenylarseneoxide plus potassium iodide was added to the chlorin-

ated sewage sample fellowed by Hdrochloric acid solution; whereas,

in the acid amperometrio method, hydroohlorio acid was added to

the ehlorinated sewage sample fbllowed hy the phenylarseneoxide

plus potassium iodide„ In both methods, the sample was then back-

titrated with iodine; and the end—point noted in both of these

methods hy the permnent doflectio of the mioroammeter needle,

The starch amperoetric method is a modification of the neutral

aperometric method, wherein, starch solution is added prior to

baok—titrating with iodine and the appearance of the blue color

indicated the end—point,

wildes

All sewage samples were obtained from the primary clarifier

effluent at the V, P, I, Sewage Treatment Plant, Blacksburg,

Virginia, (Figure 2), Since only one—hal£ of the primary clarifier

was in operation during the summer months, these samples were taken

from the middle of the eastern olarifier midway between the concrete

-18-

baffle end the effluent wair, The ohlorine demand sample was ob-

tained by employing a dipper to fill a five··gal1om container with

the eewage.ümäwas.

&§@ Q Each chlorixxe residusl test used in

this study required a separate time schedule so that the operator

coxüd set up the chlorinated sewege samples and rum the desired

chlorine residual test to determine the chlorine demand, The ampero-

metric methods were set up for 6. four•miuute time schedule; although

the neutral amperomstric method was later deoreasad to a two··m;L¤ute

schedule, The acid ortho tolidine method was set up for a six-

minute schedule; but, when wo turbidity compensating comparators

were available, this time schedule was decreaeed to three minutes.

Since the acid smparometric method and the acid ortho tolidiue method

were run from the same ohlorinated sewage sample, their time schedule

depended on the comparetcre available for use, The starch iodide

methods were set up for a two-minute schedule,

The sewage, in the five·gal1on container, was mixed and a 1500

ml. baaker was filled with the sewage. Two hundred and fifty mls.

ofthesewagewerepouredintoaminimw¤offmu·sndama:d.m¤mcf

eißt 1000 ml, flaske, As the first chlorine dosage (see Appendices

for preparation of chlorine solution) was added to 250 mls• of sewage,

III

ßI

-19-

the stop watch was started. Immediately after addition of the

chlorine, the chlorinated sewage was mixed by rotating the flask for

one minute, After a time lapse of 2, 3, 4, or 6 minutes dependiug

on the chlcrine residusl test to be made, the next chlorine dosage

we added to the following sewage sample which was mixed for one

minute. This procedure was continued until the desired number of

samples had been chlorinated•

when the fifteen minutes had elapsed from the time of the

chlorination, the desired chlorine residual test was made, Another

sample was run according to the time schedule so that a fiftean

minute contact period was given to each chlorinated sample, 'During

some of the runs, samples were being chlorinated while other samples

were being tested for a chlorine rcsidual; however, a sample was

never ohlorinated at the same time that a chlorine residual test

was to be made.

Neutral §_;t_gr__g1g lgädg _Mp;tj1_gQs The praparation of reagents which

were used in the neutral stsrch iodidc method is explained in the

Appendioes, When the 15 minute contact period ended, 2,5 mls. of

potassium iodide solution was added to the sample, The sample was

mixed and one ml. of starch solution was added. If a blue color

appeared, the sample was titrated with 0,01 H sedium thiosulfate

solution until the blue color disappeared.

I

-20-

The preparation of reagents which

were used in the acid starch iodide method is explained in the

Appendices, When the fifteen minute contact period ended, 2,5 mls,

of 50 per cent glacial acetic acid solution, folloxwd by 2,5 mls, of

potassium iodide, was added to the chlorinated sewage sample, The

sample was mixed and one ml, of starch solution was added to the

sample, If a blue color appeered, the sample was titrated with

0,01 N sodium thiosulfate until the blue color disappeered,

{leid Q_1;_t@ Tgidine g;ip__1g1_gd_s The preparation of reagents used in

the acid ortho tolidine method is explained in the Appendices, This

chlorine residusl test was made using a Hallace and Tiernen compar-

ator, when the fifbeen minute contact period ended, 15 mls, of the

chlorinated sewage sample were poured into the sample tube which com-

tained 0,75 mls, of acid ortho tolidine reagent, Another 15 mls,

were poured into the other sample tube, After the sample tubes had

been placed in the ·compa.rato1·, the comparator was placed in the dark

for five minute color development, When the five minute period ended,

the comparator was taken out of the dark and, by looking into the eye

piece and rotating the color disk, the chlorine residual of the sample

was obtained,

{gg @„___ho_d_: The prepsration of reagents which

were used in the neutral. amperometric method is expladned in the

Appendices, This chlorine residual test was made using a !»IaJ.ls.ce amd

II

I...21..

Tiernan amperometric titratom when the fifteen minute contactperiod ended, five mls. of 0,00564 N pherxylarseneoadde plus potas-eium iodide was added to 200 mls• of the chlorinated sewage sample.After thorough miudng, two mls. of H hydroohloric acid was added

to the sample, which was then titrated with 0,0282 N iodine solu-tion, The permanent deflection of the micrcemnetor needle to the

right indicated the end-point•Agig §_e_t_hg: The preparation of reagents which

were used in the acid amperometric method is explained in theAppendices, This chlorine residual test was made using a Wallaceand Tiernan amperosuetric titrator, when the fifteen minute contact

period ended, two als, of H hydrocblcric acid was added, with agita·-tion, to the 200 mls, of chlorinated sewage sample, Then five ml.cf 0,00564 N phenylarseneoxide solution was added and the sample

titrated with the 0,0282 E iodine solution, The permanent deflec-·tion of the microamneter needle to the right indicated the end—··point,

The preparation of reagents which

were used in the starch amperometric method is explained in the

Appandioes, This chlorine residual test required that a light be_

used to determine when the blue color appeared along with a Wallace

and Tiernan amperonetric titrator, the fifteen minute contact

period ended, five mls, of 0,00562 E phenylarseneoxide solution was

added to 200 mls, of chlorinated sewagc. After thorough mixing, two

,-22- E

mls, of H hydrochloric acid was added followed by che ml, of starch

solution, The mixture was then titrated with 0,0282 H iodine solu-

tion to the blue color end-point,

The data that was ebtained by the chlorine demand determine-

tion methods is tabulat• in Tables 1, 3, .4., 6, 7, 8, end 9, and

the ccrresponding results pletted gaphioally in Figures 3, lu 5,

6, 7, and 8, The method ef least equeree, which was used to corre-

Late the ebtained data i presented in Tables 2, 10, ll, 12, end 13

with the excepticn of the acid starch iodide end neutral ampero-

metric chlcrine demanda which ie presented in Table 5,

LL

-23-I

Table 1Neutral, end Acid Stareh Iodide

Ghlerine Demands

Date Time Chleriue Demand Ghloriue Demanduv by

Neutral Starch Acid StarchIedide Iodide(mm,) (pps,)

August 21 12:00 4,44 4,20August 21 1:00 4,64 4,62August 22 9:05 3,45 3,14August 22 11:30 4,56 4,18August 22 12: 30 4,00 3,05August 28 10:15 4,02 3,54August 28 11:40 5,16 4,82August 28 12:40 4,46 3,66August 29 10:15 3,20 2,80August 29 11:40 4,40 4,20 IAugust 29 12:40 6,00 5,45 IAugust 29 1:/,5 5,60 3.80 IAugust 29 3:00 4,20 3,20 IAugust 30 9:30 3,80 2,80 IAugust 30 11:30 4,60 4,00 ISeptember 17 9:50 2,50 1,90

’

September 17 10:40 2,90 2,30II

III

I

I

-24-

Table 2” Gcrrelation of Neutral and Acid Starck Iodida

Ghlorine Dmands

Number Acid Neutral (x)2 (1;) (y)of Starck Starck

Runs Icdide Ioöidc(n) (x) (Y) __1 4,20 4,44 17,6400 18,64801 4«62 4,64 21,3444 21,43681 3,14 3,84 9,8596 12,05761 4,18 4,56 17,4724 19,06081 3,05 4,00 9,3025 12,20001 3,54 4,02 12,5316 14,23081 4,ä 5,16 23,2324 24,87121 3,66 4,46 13,3956 16,32361 2,00 3,20 7,8400 8,96001 4,20 4,40 17,6400 18,48001 5,45 6,00 29,7025 32,70001 3,80 5,60 14,4400 21,28001 3,20 4,20 10,2400 13,44001 2,80 3,80 7,8400 10,64001 4,00 4,60 16,0000 18,4000

* 1 1,90 2,50 3,6100 4,75001 Ä 2,30 2,90 5,2900 6,670017 61,66 72,32 237,3810 274,1488

61.66 2 4- 1*/.001, , 72.32 = 0 21;231,2QQg j; @,66}: - 274,148_§ ; 0 2

Salva aimultauacusly for a

a I '6058.7

Substitute 0,8*7 for a in cquaticm (1)

b 2 + 3-•U9

Eqläßtiütl of 1388*0 fit Y 3 0,8*71: -6 1,09 Ä

..26-

Table 3Neutral Starck Iodida and Neutral

Amperemetric Ghlorius Demauds

Date Time Ghlerine Demand Ghlwins Demandbv bvNeutral Amperemetrio Neutral

(ppm.) Starck Iedide(pm.)August 21 10:00 4.00 3.8/.August 21 12:00 4../.0 ‘ /..4-I.August 21 1:00 /..41. 4.6/.August 21 2:00 4,36 4,02August 22 9:05 3.98 3.48August 22 10:05 3.& 3.10August 22 11:30 /..4-0 4.56August 22 12:30 /..20 4..00August 28 10:15 /..36 4.02August 28 11:40 4.88 5.16August 28 12:40 4,60 4,46August 29 11:/.0 /..56 /..40August 29 12:/.0 5.56 6.00August 29 1:45 5.22 A.60August 29 3:00 /..30 4.20August 30 9:30 4.02 3.80

ä August 30 11:30 4.56 4,60

Table Z,

Acid Starck Iodide and Neutral Ampsrcmctric

Chleriue Demauds

Data Time Ghlcrine Demand Ghlorius Demandbi 9 by

Neutral Acid StarckAmpsrcmctric Iodids(ppm) (ppm)

August 21 12:00 4.40 4.20August 21 1:00 4.44 4,62

August 22 1.1:30 4.40 4.18August 22 12:30 4,20 3,05August 28 10:15 l„36 3.54August 28 11:40 4.88 4•82August 28 12:40 4.60 3.66August 29 11:40 4.56 4.20August 29 12:40 5.56 5.45August 29 1:45 5.22 3.80August 29 3:00 4.30 3.20August 30 9:30 4.02 2.00August 30 11:30 4.56 .4,00

I..;39...

Table 5Ccrrelatiem cf Acid Starck Iedida ami Neutral

Ampercmetric Ghlcrine Demande

Neutral ampermetric and neutral starch iedide titraticcu

cquatim of beat fit:

Y ¤ 0,596% 4- 1,846 (1)

Neutral and acid etarch icdide titraticm equation of best

fit:y2

2 7-2subatxtuta y2 for ::2 in aquarien (1)

Y • 0,596(0,87x ·I· 1,09) + 1,846

y ; 0,518: 4- 0,650 4- 1,846

Equatioza cf best fit:' Y ¤ 0,52X + 2,49 I

E

4Table 6

Acid Qstho Tolidim and Neutral Ampercmstric

Chlcrius Demands

Date Time Ghlozcius Dmaud Ghloriue Demand. by by A

7 Neutral Acid Ortho °Amperometric Tolidiue(pm.) (pm.)

July 26 11:15 4.805

5.76July 26 1:45 4.45 5.80July 27 8:15 4.18 5.56July 27 11:00 4,90 6,04July 31 9:35 4.14 5.12August 2 11:30 5,18 6,20August 8 9:30 4.16 5.10August 8 1:05 4.10 4.85August 8 2:55 4.30 5.05August 10 10:00 4.50 5.66August 15 9:20 4.40 5.50August 19 1:30 4.14 5.55August 20 1:25 4.46 5.70August 20 3:00 3.84 5.10August 20 4:15 3.55 4.24

_ August 21 10:00 4.00 4.96

II

a ···33··

Table 7

Acid Ortho Tolidiue and Acid Amperometric

Ohloriue Demands

Date Time Ohloriue Dsuuaud Chlcriue DemandW W

Acid Acid OrthcAmpmtmetric Tclidine(ppm.) (ppm.)

July 26 11:15 5.98 5.76July 26 1:45 5.80 5.80July 2'7 8:15 5.20 5.56July 27 11:00 5.94 6.0/:,July 31 9:35 5.24 5.12August 2 11:30 6.25 6.20August 8 9:30 5.20 5.10

August 10 10:00 5.70 5.66August 15 9:20 5.58 5.50August 19 1:30 5.60 5.55Allgllßt AMOO 3•9OAugust 20 1:25 5.92 5.70August 20 3:00 5.,28 5.10August 20 4:15 4.32 4.24August 21 10:00 5.10 4.96

..35-

Table 8

Neutral und Acid Awercmstris Ghlorine Demands

Date Time Chloriä Demand Chlorilxägv DemandNeutral Acid Amper-

Amperemetric emetric(pm.) (mm.)July 7 9:30 4.00 /+.85

July ll 9:15 4.00 /:.96Jul? 12 9:00 /+.37 5.60July 26 8:50 /+.32 5.16July 26 11:15 4.80 5.98

-, July 26 1:45 4.45 5.80July 2'7 8:15 /+.18 5.20July 27 11:00 4.90 5.94July 31 9:35 4.1/+ 5.2/+August 2 8:45 4.17 5.20August 2 11:30 5.18 6,25August 6 9:00 4.06 4.98August 8 9:30 4.16 5.20August 8 2:55 4.30 5.30August 9 u 8:55 3.30 3.46August 10 10:00 4.60 5.70August 13 9:10 3.56 4.30August 15 9:20 /+./+0 5.58Äugllßt 19 1:30 4.14 5.60August 19 3:15 3.20 4.00August 20 1:25 4.46 5.92Augllßt 20 BBÜÜ3•8A-August20 4:15 3.55 4.32August 21 10:00 4.00 5.10

z

..37..

Table 9

Neutral ami Stareh Ampermuetric

Ghleriue Demunda

Date Tim Ghlorine Demand Chloriue Demandby bvNeutral Starch

Ampemtric Ampercmetrie(pm.) (ppm.)August 6 9:00 4.06 4,08August 8 9:30 4.16 1,,,30 —August 8 1:05 4.10 4.20August 8 2:55 4.30 4.36Augvßt 9 8:50 3.30 3.42August 10 10:00 - 4.50 4,60August 13 9:10 3.56 3.66

—38~

IV, DISCUSSIO G RESULTS

Figure 11 shows the graphical correlation which exists between

the chlorine demand determination methods, based on the neutral

amperometric chlorine demand, Marks, Joiner, and Strandskov (8),

and Strandskov, Marks, and Herehler (10) fond that the neutral

amperometric mthod could be crrelated with the bacterial reduc-

tien in sewage; whereae the other method, used in this study, could

net he cerrelatedg therefore, the results obtained are correlated

with respect to the neutral ampermetric method,

The neutral etarch iodide method end-point was not es definite

as the acid starch iodide method end—point, Apparently, the addi-

tion of glacial acetie acid made the end-point in the acid starch

iodide method more definite than the endepoint in the neutral starch

iodide end»point•

As can be seen from Table 1 and Figures 3 end ll, the chlorine

demand by the neutral starch iodide method was greater than the acid

starch iodide chlorine demand, When solving the equation of best

fit, (Table 2) y'¤ ,87x 4 1,09, the following correlatio exists

between the two methode:

E..;„g-.

Chlorine Demand Ghlorine Demand

Acid Stagzrh Iodide Neutral Säch Iodide(mm.) (pm.)2,00 2.833.00 3.704.00 4.575.00 5.44

As the strength of the sewage inoreaeed, the ehlorine demand by the

acid starch iodide method was progressively approaching the chlorine

demand by the neutral starch iodide method.

The acid starch iodide method gave erratio results, at times es

reported by Marks, Joiner, and Strandskov (8), The neutral starch

iodide method had a chlorine demand of 3,10 ppm,; however, when

3,00 ppm, of chlorine were added, the acid starch iodide method had

a chlorine residual content of 4,35 ppm,

äeutrg §__t_ggh lggdg gd gpergtrio

As can be seen from Table 3 and Figures 4 and ll, the chlorine

demand by the neutral staroh iodide method was sometimes lower than

the neutral amperometric method and at other times the chlorine

demand by the neutral etarch iodide method was greater than the neu-

tral amperometric ohlorine demand, When solving the equaticm of best

fit: (Tabh 10): 7 ¤ .596x ·|· 1,846, the following correlation eusta

between the two methods:

.4;.

Ghlorine Demand Chlorine Demand

Neutral Artgaeroxuetric Neutral Sitäärch Iodide(ppm-) (ppm.)3.00 1.934.00 _ 3.645,00 5,286.00 6.97

The ehloräne demand of both the neutral atarch iodide and neu-

tral amperometric methode la identieal at A.5'7 ppm. At a ohlorine

demand greater than A. 5*7 ppm. , the neutral atarch iodide method

inereaaes more than the neutral amperometrio chlorine demand, At a

chlorine demnd less than 4..57 ppm, , the neutral starch iodide chlo-

rine demand decreaaes more than the neutral amperometrio cblorine

demand.

§_t_a_r___o_h_ }__;_;_•di__d_e_ gd Ngutgal @rometrio

As can be seen from Table L and Figures 5 end ll, the chlorine

demand by the acid atarch iodide method was sometimes lower than the

neutral amperometric chlorine demand and at other times the chlorine

demand by the acid etarch iedide method was greater than the neutral

amperometrio chlorine demand, The required number of tests were not

completed ao that a oorrelation between the two methods could not be

made using the method of least squaree; however, the equation of best

fit, (Table 5) , was obtained by aolving the equations for the neutral

uV

..,/2.,.

amperemetrio and neutral etarch iodide methode with the neutral and

acid etarch iodide methode. When solving the equation of beat fit,

Y z .52x 4 2.49, the following correlation exists between the two

methods:

Ghlorine Demand Chlorine Demand

Neutral Aääeroetric Acid Sagäh Iodide(ppm.) (ppm.)3.00 .984.00 2.905.00 4.826.00 6.71.

The chlorine demand of both the neutral amperemetric and acid starch

iodide methods are identical at 5.18 ppm. At a chlorine demand greater

than 5.18 pm., the acid etarch iodide method inceaeee more than the

neutral amperemetric ethod. tt a chlorine demand lese than 5.18 ppm.,

the acid etarch iodide method decreaeee more than the neutral amper—

emetric method.

held ESM leädaiaeradQhlggineDemägds

Nitrite interference was noted in the acid orthe tclidine methods

during the morning houre; however, the nitratee did not interfere in

the neutral amperometric method.

As can be seen from Table 6 and Figures 6 and 11, the chlorine

demand by the acid orthe tolidine method was more than the neutral

I

.../P}.,

amperometric chlorine demand, When solving the equation of best fit,

(Tat)18 y= •73x "‘ ,384,, thö GOI'1"B].3.t•iOI1 BXÄSÜS ÖOÜVGGII

the two methods:

Chlorine Demand Chlorine Demand

Neutral Aääerometrio Acid Ortäyo Tolidine(ppm) (ppm)3•00 BAL!+•00 4.895.00 6.356.00 7.80

As the strength of the sevage increaeed, the acid ortho tolidine

method ckitorine demand was progreseively more than the neutral amper-·

ometric chlorine demand,

2.212 @$.9. 12121129. @.229119.äl21‘£2Mam.12

Nitrites did not interfere with the acid ampercmetric method;

however, the acid ortho tolidine method could not be run during the

morning hours because of nitrite interfcrcnceu

As can be seen from Table 7 end Figures 7 and 11, the chlorine Idemand by both of these methods are approximately the same, when

isolving the equaticm of best fit, (Table 12) y • 1,03 - 0,087, the I

following correlation exists between the two methods: III

I

..4;..

Chlorine Demand Ghlorine DemandAcid Klrtläjci Tolidine Acid Amgärometric 3(ppm) (ppm) I

4.00 4.03 w5.00 5.06 36.00 6.09 {

Therefore, it can be said that these two methods indicate thesameohlorinedemand in settled domesticsewage.It

is sigxificant to notice that both ef these methods,whichareaoidified with hydrochloric acid, indicate a chlorinedemandequally

geater than that of the neutral ampercmetriochlorinedemand;

therefore, it is aesumed that the hydrochlorio acid must Icause this discrepancy in these chlorine demanddeterndnations.Eaasszd

ess asia. Qhkniap.i

These wo methods required the same reagents but in the neu-Itral amperometric method, phenylarseneoxide solution was added folien- ,

ed by the hydrochloric acid solution, and, in the acid amperometric

method, hydrcofücric acid solution was added followed by the phenylar-

seneeucide solution. In the neutral amperometric method, the residual

chlorine present oombined with the phemlarseneoxide plus potassium

iodide at a neutral pH and the back titration with the iodine was

made at a pH of 2.5. In the acid ampermetric method, the solution

was acidified and the chlorine residual present oombined with the

I

phenylarseneoxide plus potassium iodide at a pH cf 2,5, The back

_ -46-titrationwith the iodine solution was made et a pH of 2,5; therefore,

the time of acidifying the chlorinated aewage sample was the difference

between the two methods,As can be seen from Table 8 and Figures 8 end ll, the chlorine

demand by the acid amperometric method was more than the neutral

amperometrie ohlccrine demand, when eolving the equation of best fit,

(Table 137 Y : ,66611: 4 ,693, the following correlation exists between

the two methode:Ghlorine Demand Chlorine Demand

Neutral Eperometrio Acid Amäirometric(pm,) (pm,)3,00 3,454,00 4,955,00 6,456,00 7,95

l Aa the strength of the sewege inereaeed, the acid amperometric method

ohlorine demand was progreseively more than the chlorine demand by

the neutral amperometrio method,

daaäal @ ääaä l”..........a¥@’¤h<><?«The staroh ampermwtric method was made in conjunctien with the

neutral emperometric method to determine if the same relation ae ob-

tained by hhrks, Joiner, end Strandekov (7) was found,Aa can be seen km Table 9, the ehlorine demand of the starch

amperometric method was approudmately 0,10 ppm, greater than the

N

NNneutral amperometric method, The neutral amperometric end-·poiut

was more sensitive then the atereh amperometric end-point,

I-

{

{-47- {{

V, CONGLUSIONSE

1. The chlcrine demand correlations, which exist in the settled {domestic sewage at the V, P. I, Savage Treatment Plant between {the limits of one and seven pm, of applied, chlcrine dcsage, are

Ees followss {(a) Neutral starch icdide (1:) and neutral amperometric (y) E

relationship ·· y n .5961: 4 1.846. {(b) Acid atarch icdide (1:) and neutral ampercmetric

(y)Yßletiwßhip······ Y == .521: 42,4,9,(c)Acid crbho tclidine (1:) and neutral amperometric(y)relationship·- y ·;,· .73x 4 ,384, {

(d) Acid ampercmetric (1:) and neutral amperometric (y) {

reletivnßhip ···· sr a .666:: + .693. {

(e) Acid starch meine (1:) and neutral am-eh ieaiae (y) {!’@l&'€·i<>¤ShiP ·••* Y : 0.8%+1.09.(if')Acid artho tclidine (rx:) and acid amperometric (y) {

relationship -—-— y z 1,03;; - 0,087,{

2, The acid ampercmetric and acid orthe tolidine methods indicate {

approximately the same chlorine demand in settleddcmesticaewage,3,

Nitritee do not interfere with the acid or neutral ampercmetric {methode.{

{

S ;SSS

4, The end-point in the acid etareh iodide methcd ie more defiuite

them the neutral etareh iodide methoch5. The visible eterch emperemetrie method ie not ae sensitive ae

«the neutral ampercmetric method for detemining the chlorine Edemand. S

SSSSSSSSSS

S

LL•·!+9•·- ßVI. AGm§The author wishes to express his spprecitzicm to Dr. L, G, Richand Professors R, C, Briuker, J, A, Rives and P, H, Moüaubey for

making this investigation possible; to Mr, R, E, Opferkush fortechnical assistance; and to Dr, L. G, Rieh and Mr, R, E,Opferkush for editing assistance,

LLLL

L LL L, LL L

II-50-VIII,

BIBLIOGaAPH1'(

seem Qilad.(1) Annan, **wa11aco and 'riornan Instructions for Installation,

Operation and Maintenance of Wallace and Tiernan Apparatusß

Newark 1, New Jersey,

(2) American Public Health Association and American Water Works

äiwäé. Ass aiHalse:gggg, · American Public Health Association,

(1948),(3)Chamberlin, N, S, "Ths Dotmninatinn of man cnlorinsQ,(1942),(4)

¤e<,¤,<><¤-¤@· 5Shepperd-lhnn Publishing 0o1·p¤1·at1on, Paß, 220-2.6,2,(1946),(5)Hanksiaxann, H, and may, a, ·*¤1s1nrsst1sn of Savage na-tnChlorine, III, Factors Affecting Ccliforms Remsining andOorrolation of Ortho·to1idine and Amperometric Chlorine

Rssidnslsß ggg wg; ÄIQQ., gg, 155, (1951).(6) Barks, H, C, and Glass, J, R, "A New Method ofDeterminingRasidwl

¤¥=1¤¤·=‘!-¤¤•" £@'L s£ wlw Hs~1>.a IlznlsaAsse;-an-ggg,Q 1227, (1942}. I(7) Maas, a, c. and Joanna-, R. a, ·*¤ata·nanat1an of assisns.1

in Savage} Q 119*7, (191,8). 5(8) lhrks, H, C,, Joinsr, R, R, and Strandskov, F, B, "Ampcro—· E

metric Titration of Raaidual Chloriue inSewage,"gwwggw,gg, 1*75, (1948),I

..51..

(9) Nusbaum end Meyereon, L. A. Wetemxination of ChlorineDemands and Chlorine Resicluale in Savage} gggg

22. 968. (1951).(10) Strandekov, F. B., mrka, H, C. and Hcrchler, D. H, ”App1ica-

tion of a New Residual Chlorine Method to Chlorinated Ei'fluont,”ggglgggg g‘_gg._r__:g;, gg, 23., (1%,9).

Literatzme äcamined1. Beardaley, C, M, ‘*Disiz1feo‘tion by Subreeidual Chlorination,"

1094-• (1950)-2. Chamberlin, N. S. 'Wßblerination of Sewe.ge,”’ gg gang ggg-

ää ¥iag_§9_, @,9,, 30:5,, (1948).3. Faber, H. A. "Gontmuporary Chlorination Practice," §g__1:m__n_Q.__ gg

t__[g._tg_r_ }_~gg}__:g_ Aggocigicm, 32, 200, (1947).

L., Ibid. '*The Chlorination of Sewage and Industrial Was‘te,"

E‘ggg§gg<_g_J__Qgg_r_g_g, gg, 211, (1942).5. Gard, C. M. "Experienee with Break•PointCh1o1·ination,"gd

Sewgg äjgigg, gé, A15, (1949).‘

6, Griffin, A. E. "Evaluation of Reeidual Ch1ox·ine,” Journal ggIgg, 666, (1935). „

7. Griffin, A. E. and Ghamberlin, N. S. ”EXP1OI'iI1g the Effect of IHeavy Doses of Gblorine in Sewage," Qournal, gz, I730, (1945).I

I

I8. Halliman, F. J. and Thompson, N, R, VA Critical Study of i

the Thiosulfate Titration of Chlorina," Journal gi gggIAmaricggä Chemical Society, gl, 265, (1939). {

9. Harvill, C. H. Morgan, J. H., and Mauzy, H. L. '*Praot5.ca1lApplicationof Ammonia—Induead Braak·-Point Ch1orir1ation,"

Amergacg ;g_a_t_a__1y_ Agsgcggtion, 14,, 275,(1942).10,

Heukelakian, H, "Disinfaction of Savage with Chlorina,IV,Afbergrwthof Coliform Organisms in Streams Receiviug EClalorinatad Savage} ggg ggg Induatgal hgaßaigg, 2},

273,(1961),I

11. Heukalekian, H. and Day, R. V. “Disin.f‘ection of Savage withtChlorina, II, Method and Uniformity of Distribution of ,

Ghlorina in Savage Plants," ägg _a_.n_<}_ Induatgigl \j£g_1_@_, 22

Av, (1951).12, Keukelakian, H, and Smith, M. B, "Disiufection of Savage with

Cblorine, I, Laboratory Experiments on the Ei‘aet of Chlorina IDosages on Raeidual ColiformQrganismaß\j_a._g§_e_,

Q3, 1509,(1950).13,Mahzm, M, A, “Simp1ifiad Amporometric Titration Apparatua Efor Determining Hesidual Chlorina in Mater,“ }_{_a;_t_a_;_•_ @

i§_gs_g_a@_Vj_g;;}c_s_, QQ, 171, (1949). E

14. McLach1an, J. A. and Gaillard, J. R. "Tha SterilisationofSavageEffluents by Gaaeous Üh1OI‘iI'18,“ ¥_{qIj_<_g

E-_Q_171.,

(1948).paaaaaaa

ä-53-

15, Moore, E, W, ”F¤ndamente‘1ls of Chlorinatioxx of Savage and

Ed- 139- (1951)-16. Nagano, J, "Oxidation of Sulfidee During Sewage chlOPiH&°(Z-10H,n

Ser-rage and Industrial waste, 22, 884, (1950),

17, Rudelfs, W, *’Chlox·inatien of Sex-rage," (·>_§a_t_„g §_»f_e_1j_}5_g Sewergg,

m, 242, (mz-).18, Symons, G, E.

”A Modifieatien of the Chloriue Demand Test and

the Qrtho Telidine Test for Residual Chlorine in Sen-1ege,"

§_e_·¤_.;g&\5_g;g_;_:_g_ ,_L@_1·_qgl_,, Q, 569, (193*7)-19, Symons, G, E, , Terhoeven, G, E., and Torrey, M. L., "Laboratory

and Field Studies em Chlorine Demand of Sex-rage,” )j_g‘§_e_1; \j_g_1·k__g

gg Seweggä, §§, 789, (1938),20, Tarree, M, J, "Px·el:Lmina1·y Studies of the Cblerine Demand of

Specific. Chemical Cmpmmds}"

A2- :-62, (mso)-21, Nillacm, V, A, "Determiuation of Available Chlorine in Hypo--

chlorite Solution by Direct Titratim with Sodium Thiesulfate,"

Z- M- (1935)-

1 ·-55-·IX. APPEEDICES

R..2s.2..88 1äesab. ÄQSEEIE ..2..2118¤¤d IPatassium Iodide Solution: I

(1) Dissolve 75 yam ¢p. KI (free from iodine and iodate) Iin ana liter frashly boiled and cooled distilledwater,AcidSolutions(1) Ddlute 500 rule. af Glacial Aoetic Acid with 500 m1s„of distilled water.Starck Solution:

(1) Anke a thin paste af about 2 @8. of starch in cold

A water, Paur into 200 mle, of boiling distilled water. ·When cool add a few drops of chlouroform,Thiaeulfate Solution:(1) Make up 0,10 N sodium thioszilfate solution hy dissolv-·

$118 25 81*8-¤1S GY N82S2O3•5H20 in one liter of freshlyboiled water and allow to stand for at least two weeks.As needed standardize with 0.10 E K2G1•2O7 and dilute to0,01 N, Standardize frequently to insure strength of I0,01 N sodium thiosulfate, I

IOrtho Tolidine Reagent:(1) Dissolve l•35 mas. of ortho tolidine dihydrockloride Iin 500 mls. of distilled water. Add this solution,

I

»

·····$6- §

with constant stirring, to 500 mls, of dilute HC1 i(mix 350 mls, of distilled water and 150 mls,ofconeentratedHC1),.=;¤.a

mass EPhemrlsrseneosddeSolution:(1)

Dissolve approzcinaately 0,8 ms, ofphenylarseneoacidein

150 mls, of 0,30 N Ha0H, This solution isunstableand

should be used immediately by adding 110 mls,ofit

to 800 mls, of distilled water containing 7,5 gas, Eof KI and mix thoroughly,

s

(2) Bring to a pH of 6 to 7 with dilute HC1 and finally

dilute to one liter,(3) A 50 ml, sample is titrated with freshly standardized

0,0282 N iodine solution using starch as the iudicator,(A) Dilute with distilled water until 0,00561, N is reaohed

and titrated again,

Iodine Solutions(1) Dissolve 2 gas, of KI orystals in small qusntity of hot

boiled distilledwater,(2)When cool, add 3,173 @718, of iodine and make up to one

ßliter with distilledwater,(3)Titrate against 0,025 N sodium thiosulfate until 0,0282 N Eiodine solution is obtainedä

?

E

...5*7..

Starch Indicator:

(1) Mike a thin paste of about 2 @16, of starch in cold

water, Pour into 200 mls, of boiling water end stab',

When cool add a few drops of chloroform,

Qgorino $@1.5.011

The chlorine solution was made up daily using 95 mle. of dis-

tilled water and five mla, of "zonite"; each ml, of this solu-

tion was equivalent to two ppm, of free available chlorine per

250 mls, of sevagm

-58-

Table 10

Correlation of Nutra.1 Starch Iodide and Neutral

Amperematria Chlorine Demancla

Number Neutral Neutral 2of Starch Amparometria (xx) (X) (y)Runs Iodida(rx) (X) (1)1 3.84 4.00 14.74,56 15.36001 4.44 4.40 19.7136 19.53601 4.64 4.44 21.5296 20.60161 4.02 4,36 16.1604 17.52% _1 3.4/8 3.98 12.1104 13.85041 3.10 3.& 9,6100 11.84201 44 56 4.40 20.7936 20.06401 4.00 4,20 16.0000 16.80001 4.02 4.36 16.1604 17.52%1 5.16 4.88 19.8916 20.51601 4.46 4.60 26.6256 25.18081 4.40 4.56 19.3600 20.06401 6.00 5.56 36.0000 33.36001 5.60 5.22 31.3600 29.23201 4,20 4.30 17.6400 18.06001 3.80 4.02 14.4400 15.27601 4.60 4.56 21.1600 20.9760

17 74.32 75.66 333.3008 335.7732

74.32 6 + 17.00b -· 75.66 s 0 (1)333‘2ÜÜ88 3 *7;,,336 - 35.mZ -·_ 0 (2)

Salve aimultanaously fer 6.

8. 2: "‘

Ü•Subatitute0.596 fer 6. in aquaticm (1)

b 2: 4, 1.846

Equaticm of best fit -·-····-·-··—·--·--·-·-·~·-· y .6 .596:: 4 1.846~

-59·

Table 11Cocrrelatiou of Acid Ortho Tolidiue and Neutral BAmperometric Chlorinc Demaude

BB

Number Acid Neutral2ofOrtho Amporometric (ac) (x) (y)Runs Tolidiue(rx) (x) Lv)1 5.76 4.80 33.1776 27.6480 B1 5.80 4.45 33.6400 25.81001 5. 56 4.18 30.9136 23.2408l 6.04 4.90 36.4816 29.5960” 1 5.12 4.14 26.2144 21.19681 6,20 5.18 38,4400 32,1.1601 5.10 4.16 26,0100 21,21601 4.85 4.10 23.5225 19.88501 5.05 4.30 25.5025 21.71501 6.66 4.50 32.0356 25.47001 5. 50 4.40 30.2500 24.,2000 B1 5.55 4.14 30.8025 22.9770 ~1 3.90 3.20 · 15.2100 12.4800 B1 5.70 4.46 32.4900 25.42201 5.10 3.84 26.0100 19.58401 4.24 3.55 17.9776 15.0520

( 17 90.09 72.30 483.2795 387.44869O•® 8 + •• 2

Q QQIQQ •• O 2

Solve eimultaueoualy for 6.

Subetitute 0,73 for a in equaticm (1) B

6 = + 0.384 A BEqmmeu er 66.1; 1*16 ----—-----—-—-- y . 0.73:: 4- 0.384 T

EB

E

--60-Table 12

Correlation of Acid Orthc Tclidine and AcidAmparometric Chlorine Demande

Number Acid Acidof Ortho Amp.m¤m~1¤ (602 (X) (X)

Rune Telidiue(0) (x) (1*)1 5.76 5.98 33.1776 34.44481 6.00 6.00 33.6400 33.64001 6.04 5.94 36.4816 35.87761 5.12 5.24 26.2144 27.3408 ·1 „ 6,20 6.25 38.4400 38.75001 5.10 5,20 26,0100 26.52001 5.05 5.30 25.5025 26.76501 5.66 5.70 32,0356 32,26201 5.50 5.58 30.2500 30.69001 — 5.55 6.60 30.8025 31.08001 309040001

5.70 X 5.92 32.4900 33.74401 5.10 5,28 26,0100 26,92801 4.24 4.32 17.9776 18.31681 4.96 5.10 24.6016 25.29601 5.56 5.20 30.9136 28.912016 85.24 86.41 459-.7570 466.1670

85,21. 16.00b - 86,41 0 1ggg ggg; I 8§,2_4g •- @6,1670 Z 0 (2)

Solve aimultanaously for a

a -7 ·I· 1,03Substitute 1,03 fer a in equaticn (1)

b -7 ··· 0.087

Equatlou of best fit •·•·-·-··-•··-·-••--····-·-········· Y = 1.03X •-· 0.087

II

Table 13Correlaticn of Neutral and Acid Ampercxmetric

Chleriue Demaguda

Number Acid Neutral 2ef Ampercmetric Amperometric (1) (I) (y)Runs(u) (wr) (Y)

1 4.85 4.00 23.5225 19.40001 5.36 4.00 28.7296 21.44001 4.96 4.00 24.6016 19.84001 5.60 4.37 31.3600 24.47201 5.16 4,32 26,6256 22,29121 5.98 4.80 35.7604 28.7040' 1 5.80 4.45 33.6400 25.81001 5.20 4.18 27,0400 21.73601 5.94 4.90 35.2836 29.10601 5.24 4.14 27.9816 22.10764 1 5,20 4.17 27,0400 21.68401 6.25 5.18 39.0625 32.37501 4.98 4.06 24.0004 20.21881 5,20 4.16 27,0400 21..63201 5.30 4.30 28.0900 22.79001 3.46 3.30 11.9716 11.41801 5.70 4.50 32.4900 25.65001 4.30 4.56 18.4900 15.30801 5. 58 4.40 31.1364 24. 55201 5.60 4.14 31.3600 23.18401 4.00 3.20 16.0000 12.8000

1 5.10 3.84 26.0100 19.58401 4.32 3.55 18.6624 15.33601 5.10 4.00 26.0100 20.4000

25 130.10 103.98 687.7546 548.2418130,10 a J- 25.00b ·- 103.98 ¤ 0 (1)ggg 4 130,;,06 - gglage ll 0 (2)

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·-62..Solvs simultaxxaoualy for a.

3 S O,666Substituts 0,666 for a in equatiou (1)

b ='· 4 0.693Equation of best fit -—-•-—-—·—-——-—-——-•-••• y g 0,666:: —·|· 0•693

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