ASTM D1291-06(2011)
(Practice)Standard Practice for Estimation of Chlorine Demand of Water
Standard Practice for Estimation of Chlorine Demand of Water
SIGNIFICANCE AND USE
Chlorine is added to potable water, waste water, and industrial water for a variety of purposes. Some of these purposes are:
To eliminate or reduce the growth of microorganisms in water,
To destroy or modify decomposable organic substances so as to reduce the biochemical oxygen demand of the water,
To eliminate or reduce taste, odors, and color in the water,
To separate grease in waste water by eliminating the protective colloidal effect of proteins present, and
To destroy or modify substances in the waste water that react directly by oxidation, such as ammonia, cyanates, cyanides, ferrous iron, nitrites, phenol, phosphorus, sulfides, sulfites, thiocyanates, and other oxidizable constituents.
It is important to avoid over-chlorination in order to minimize chemical consumption, meet restrictions specified by regulatory agencies, and minimize equipment degradation.
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 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D1291 − 06(Reapproved 2011)
Standard Practice for
Estimation of Chlorine Demand of Water
This standard is issued under the fixed designation D1291; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This practice provides a means of estimating the quan- 3.1 Definitions of Terms Specific to This Standard:
tity of chlorine required to be added to a unit volume of water
3.1.1 chlorine demand—theamountofchlorinethatmustbe
to accomplish a predetermined treatment objective or to
added to a unit volume of water under specified conditions of
completely react with all chlorine reactable substances in the
pH, temperature, and contact time to completely react with all
water, or both.
chlorine-reactable substances in the water. It is defined as the
difference between the amount of chlorine applied and the
1.2 Temperature, pH, and initial chlorine dosage are all
amount of free chlorine remaining at the end of the contact
variables in estimating the optimum chlorination practice. The
period.
effects of these variables can be evaluated using this practice.
3.1.2 chlorine requirement—the amount of chlorine that
1.3 Chlorine residual is determined using Test Method
must be added to a unit volume of water under specified
D1253.
conditions of pH, temperature, and contact time to achieve the
1.4 This practice is applicable to all types of water in which
objectives of chlorination.
the stated treatment objective can be evaluated or residual
3.2 Definitions—For definitions relating to this practice, see
chlorine can be measured, or both.
Terminology D1129.
1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4. Summary of Practice
standard.
4.1 Known amounts of chlorine are added to a series of 500
1.6 This standard does not purport to address all of the
mL aliquots of sample. The treated sample aliquots are
safety concerns, if any, associated with its use. It is the
permitted to stand for a specified contact time (or a variety of
responsibility of the user of this standard to establish appro-
different specified contact times) under specified conditions of
priate safety and health practices and determine the applica-
pH and temperature.At the end of the contact time, the sample
bility of regulatory limitations prior to use. For a specific
aliquots are either analyzed for chlorine content by Test
hazard statement, see Note 1.
Method D1253 or subjected to whatever evaluative technique
is required to establish accomplishment of the treatment
2. Referenced Documents
objective, or both.
2.1 ASTM Standards:
D1129 Terminology Relating to Water
5. Significance and Use
D1193 Specification for Reagent Water
5.1 Chlorine is added to potable water, waste water, and
D1253 Test Method for Residual Chlorine in Water
industrial water for a variety of purposes. Some of these
D1293 Test Methods for pH of Water
purposes are:
D3370 Practices for Sampling Water from Closed Conduits
5.1.1 To eliminate or reduce the growth of microorganisms
in water,
5.1.2 To destroy or modify decomposable organic sub-
This practice is under the jurisdiction of ASTM Committee D19 on Water and
stances so as to reduce the biochemical oxygen demand of the
is the direct responsibility of Subcommittee D19.03 on Sampling Water and
Water-Formed Deposits, Analysis of Water for Power Generation and Process Use,
water,
On-Line Water Analysis, and Surveillance of Water.
5.1.3 To eliminate or reduce taste, odors, and color in the
Current edition approved May 1, 2011. Published June 2011. Originally
water,
approved in 1953. Last previous edition approved in 2006 as D1291 – 06. DOI:
10.1520/D1291-06R11.
5.1.4 To separate grease in waste water by eliminating the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
protective colloidal effect of proteins present, and
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.1.5 To destroy or modify substances in the waste water
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. that react directly by oxidation, such as ammonia, cyanates,
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1291 − 06 (2011)
cyanides, ferrous iron, nitrites, phenol, phosphorus, sulfides, 7.5.3 Standardize the chlorine water or sodium hypochlorite
sulfites, thiocyanates, and other oxidizable constituents. solution, standard, as follows:
7.5.3.1 Transfer 10 mLof the solution to be standardized to
5.2 It is important to avoid over-chlorination in order to
a porcelain dish.
minimize chemical consumption, meet restrictions specified by
7.5.3.2 Add 10 mL of acetic acid (1 + 1) (see 7.3) and 10
regulatory agencies, and minimize equipment degradation.
mL of potassium iodide solution (see 7.8).
7.5.3.3 Titrate with sodium thiosulfate solution (0.10 N)
6. Apparatus
(see 7.11) until the yellow color of the liberated iodine is
6.1 All of the apparatus listed in Test Methods D1293 and
almost discharged.
D1253 may be required. Any other apparatus necessary to
7.5.3.4 Add 1 mLof starch indicator solution (see 7.12) and
carry out the final evaluation of the effects of chlorination will
continue the titration to a colorless endpoint.
be required.
7.5.3.5 Calculate the concentration of available chlorine as
follows:
7. Reagents and Materials
A 3B 335.45
7.1 Purity of Reagents—Reagent grade chemicals shall be
Available chlorine, mg/mL 5
C
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit-
where:
tee onAnalytical Reagents of theAmerican Chemical Society,
A = sodium thiosulfate solution, standard, mL,
where such specifications are available. Other grades may be
B = normality of sodium thiosulfate solution, standard, 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
to Specification D1193, Type III, which has been rendered 2 2 7
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
to stand in sunlight for several hours to destroy the chlorine
7.8 Potassium Iodide Solution (50 g/L)—Dissolve 50 g of
residuals. Test Method D1253 may be used to assure complete
potassiumiodide(KI)in1Loffreshlyboiledandcooledwater.
destruction of these residuals.
Add1gof sodium bicarbonate (NaHCO ) to stabilize the
7.3 Acetic Acid Solution (1+1)—Mix equal volumes of solution. Store in an amber bottle and avoid direct exposure to
sunlight.
glacial acetic acid and water.
7.4 Calcium Hydroxide Solution (10.7 g/L)—Weigh 10.7 g
7.9 Sodium Hydroxide Solution (10 g/L)—Dissolve 10 g of
of100 %hydratedlime,Ca(OH) ,andsuspendinwater.Dilute sodium hydroxide (NaOH) in water and dilute to 1 L.
the suspension to 1 L. Shake well each time before using.
NOTE 2—Caution: Heat is generated when dissolving sodium hydrox-
7.5 Chlorine Solution, Standard—Prepare one of the stan- ide in water.
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 .
water. Dissolve the compound in the water by shaking and
periodic inversion.Add1gof sodium carbonate (Na CO ) and
NOTE 1—Warning: Use a slow rate of addition and carry out the
2 3
operation under a hood. Store in a glass stoppered amber bottle and
dissolve. Dilute the solution to 1 L with water.
standardize daily before use.
7.10.1 Standardize the sodium thiosulfate solution: Add 70
7.5.2 Sodium Hypochlorite Solution, Standard—Dilute a
mLofwatertoaporcelaindish,andadd,withconstantstirring,
commercial sodium hypochlorite or bleach solution containing
1 mL of concentrated sulfuric acid (H SO ), 10.0 mL of 0.100
2 4
10 to 100 g of available chlorine per litre with water to provide
N K Cr O , and 20 mL of potassium iodide solution (see 7.8).
2 2 7
a solution containing from 0.5 to 10 mg available chlorine per
Permit the reaction mixture to stand in the dark for about six
litre, depending upon the maximum expected chlorine require-
minutes. Then titrate with the sodium thiosulfate solution until
ment for the s
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