ASTM D1291-89(1994)e1
(Practice)Standard Practice for Estimation of Chlorine Requirement or Demand of Water, or Both
Standard Practice for Estimation of Chlorine Requirement or Demand of Water, or Both
SCOPE
1.1 This practice provides a means of estimating the quantity of chlorine required to be added to a unit volume of water to accomplish a predetermined treatment objective or to completely react with all chlorine reactable substances in the water, or both.
1.2 Temperature, pH, and initial chlorine dosage are all variables in estimating the optimum chlorination practice. The effects of these variables can be evaluated using this practice.
1.3 Chlorine residual is determined using Test Method D1253.
1.4 This practice is applicable to all types of water in which the stated treatment objective can be evaluated or residual chlorine can be measured, or both.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see Note 1.
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e1
Designation: D 1291 – 89 (Reapproved1994)
Standard Practice for
Estimation of Chlorine Requirement or Demand of Water, or
Both
This standard is issued under the fixed designation D 1291; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Section 12, Keywords, was added editorially in April 1994.
1. Scope all chlorine-reactable substances in the water. It is defined as
the difference between the amount of chlorine applied and the
1.1 This practice provides a means of estimating the quan-
amount of free chlorine remaining at the end of the contact
tity of chlorine required to be added to a unit volume of water
period.
to accomplish a predetermined treatment objective or to
3.1.2 chlorine requirement—the amount of chlorine that
completely react with all chlorine reactable substances in the
must be added to a unit volume of water under specified
water, or both.
conditions of pH, temperature, and contact time to achieve the
1.2 Temperature, pH, and initial chlorine dosage are all
objectives of chlorination.
variables in estimating the optimum chlorination practice. The
3.2 Definitions—For definitions relating to this practice, see
effects of these variables can be evaluated using this practice.
Terminology D 1129.
1.3 Chlorine residual is determined using Test Method
D 1253.
4. Summary of Practice
1.4 This practice is applicable to all types of water in which
4.1 Known amounts of chlorine are added to a series of 500
the stated treatment objective can be evaluated or residual
mL aliquots of sample. The treated sample aliquots are
chlorine can be measured, or both.
permitted to stand for a specified contact time (or a variety of
1.5 This standard does not purport to address all of the
different specified contact times) under specified conditions of
safety concerns, if any, associated with its use. It is the
pH and temperature. At the end of the contact time, the sample
responsibility of the user of this standard to establish appro-
aliquots are either analyzed for chlorine content by Test
priate safety and health practices and determine the applica-
Method D 1253 or subjected to whatever evaluative technique
bility of regulatory limitations prior to use. For a specific
is required to establish accomplishment of the treatment
hazard statement, see Note 1.
objective, or both.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards:
5.1 Chlorine is added to potable water, waste water, and
D 1129 Terminology Relating to Water
2 industrial water for a variety of purposes. Some of these
D 1193 Specification for Reagent Water
2 purposes are:
D 1253 Test Method for Residual Chlorine in Water
2 5.1.1 To eliminate or reduce the growth of microorganisms
D 1293 Test Methods for pH of Water
in water,
D 3370 Practices for Sampling Water from Closed Con-
2 5.1.2 To destroy or modify decomposable organic sub-
duits
stances so as to reduce the biochemical oxygen demand of the
3. Terminology water,
5.1.3 To eliminate or reduce taste, odors, and color in the
3.1 Definitions of Terms Specific to This Standard:
water,
3.1.1 chlorine demand—the amount of chlorine that must
5.1.4 To separate grease in waste water by eliminating the
be added to a unit volume of water under specified conditions
protective colloidal effect of proteins present, and
of pH, temperature, and contact time to completely react with
5.1.5 To destroy or modify substances in the waste water
that react directly by oxidation, such as ammonia, cyanates,
This practice is under the jurisdiction of ASTM Committee D19 on Water and cyanides, ferrous iron, nitrites, phenol, phosphorus, sulfides,
is the direct responsibility of Subcommittee D19.03 on Sampling of Water and
sulfites, thiocyanates, and other oxidizable constituents.
Water-Formed Deposits, Surveillance of Water, and Flow Measurement of Water.
5.2 It is important to avoid over-chlorination in order to
Current edition approved Oct. 27, 1989. Published December 1989. Originally
e 1
minimize chemical consumption, meet restrictions specified by
published as D 1291 – 53T. Last previous edition D 1291 – 81 .
Annual Book of ASTM Standards, Vol 11.01.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 1291
regulatory agencies, and minimize equipment degradation. 7.5.3.3 Titrate with sodium thiosulfate solution (0.10 N)
(see 7.11) until the yellow color of the liberated iodine is
6. Apparatus
almost discharged.
7.5.3.4 Add 1 mL of starch indicator solution (see 7.12) and
6.1 All of the apparatus listed in Test Methods D 1293 and
continue the titration to a colorless endpoint.
D 1253 may be required. Any other apparatus necessary to
7.5.3.5 Calculate the concentration of available chlorine as
carry out the final evaluation of the effects of chlorination will
follows:
be required.
A 3 B3 35.45
Available chlorine, mg/mL 5
7. Reagents and Materials
C
7.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
where:
all reagents shall conform to the specifications of the Commit-
A = sodium thiosulfate solution, standard, mL,
tee on Analytical Reagents of the American Chemical Society,
B = normality of sodium thiosulfate solution, standard,
where such specifications are available. Other grades may be
and
used, provided it is first ascertained that the reagent is of
C = chlorine solution titrated, mL.
sufficiently high purity to permit its use without lessening the
7.6 Hydrochloric Acid (1 + 1)—Mix equal volumes of con-
accuracy of the determination.
centrated HCl (sp gr 1.19) and water.
7.2 Purity of Water—Unless otherwise indicated, references
7.7 Potassium Dichromate Solution (0.100 N)—Dissolve
to water shall be understood to mean reagent water conforming
4.904 g of anhydrous potassium dichromate (K Cr O)of
2 2 7
to Specification D 1193, Type III, which has been rendered
primary standard quality in water and dilute to 1000 mL in a
chlorine demand-free. Chlorine demand can be removed by
volumetric flask.
treating with excess chlorine and allowing this treated solution
7.8 Potassium Iodide Solution (50 g/L)—Dissolve 50 g of
to stand in sunlight for several hours to destroy the chlorine
potassium iodide (KI) in 1 L of freshly boiled and cooled water.
residuals. Test Method D 1253 may be used to assure complete
Add1gof sodium bicarbonate (NaHCO ) to stabilize the
destruction of these residuals.
solution. Store in an amber bottle and avoid direct exposure to
7.3 Acetic Acid Solution (1 + 1)—Mix equal volumes of
sunlight.
glacial acetic acid and water.
7.9 Sodium Hydroxide Solution (10 g/L)—Dissolve 10 g of
7.4 Calcium Hydroxide Solution (10.7 g/L)—Weigh 10.7 g
sodium hydroxide (NaOH) in water and dilute to 1 L.
of 100 % hydrated lime, Ca(OH) , and suspend in water. Dilute
NOTE 2—Caution: Heat is generated when dissolving sodium hydrox-
the suspension to 1 L. Shake well each time before using.
ide in water.
7.5 Chlorine Solution, Standard—Prepare one of the stan-
dard solutions described in 7.5.1 and 7.5.2; standardize as
7.10 Sodium Thiosulfate Solution, Standard (0.10 N)—
described in 7.5.3.
Transfer 25 g of sodium thiosulfate pentahydrate (Na S O ·
2 2 3
7.5.1 Chlorine Water—Pass chlorine gas through reagent
5H O) to a 1-L volumetric flask containing about 800 mL
water until the solution contains from 0.5 to 10.0 mg/L Cl .
2 water. Dissolve the compound in the water by shaking and
periodic inversion. Add1gof sodium carbonate (Na CO ) and
2 3
NOTE 1—Warning: Use a slow rate of addition and carry out the
dissolve. Dilute the solution to 1 L with water.
operation under a hood. Store in a glass stoppered amber bottle and
standardize daily before use. 7.10.1 Standardize the sodium thiosulfate solution: Add 70
mL of water to a porcelain dish, and add, with constant stirring,
7.5.2 Sodium Hypochlorite Solution, Standard—Dilute a
1 mL of concentrated sulfuric acid (H SO ), 10.0 mL of 0.100
2 4
commercial sodium hypochlorite or bleach solution containing
N K Cr O , and 20 mL of potassium iodide solution (see 7.8).
2 2 7
10 to 100 g of available chlorine per litre with water to provide
Permit the reaction mixture to stand in the dark for about six
a solution containing from 0.5 to 10 mg available chlorine per
minutes. Then titrate with the sodium thiosulfate solution until
millilitre, depending upon the maximum expected chlorine
the yellow color of the liberated iodine is almost discharged.
requirement for the sample. This solution must be standardized
Add 1 mL of starch indicator solution (see 7.12) and continue
before use.
the titration to a colorless endpoint.
7.5.3 Standardize the chlorine water or sodium hypochlorite
7.10.1.1 The normality can be calculated as:
solution, standard, as follows:
7.5.3.1 Transfer 10 mL of the solution to be standardized to
Norm
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