ASTM D3739-94(2003)

Standard Practice for Calculation and Adjustment of the Langelier Saturation Index for Reverse Osmosis

SCOPE
1.1 This practice covers the calculation and adjustment of the Langelier saturation index for the concentrate stream of a reverse osmosis device. This index is used to determine the need for calcium carbonate scale control in the operation and design of reverse osmosis installations. This practice is applicable for concentrate streams containing up to 10 000 mg/L of total dissolved solids.
1.2 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.

General Information

• Status: Historical
• Publication Date: 09-Jun-2003
• ICS: 07.030 - Physics. Chemistry
• Technical Committee: D19 - Water
• Drafting Committee: D19.08 - Membranes and Ion Exchange Materials

Relations

• Replaces: ASTM D3739-94(1998) - Standard Practice for Calculation and Adjustment of the Langelier Saturation Index for Reverse Osmosis
• Effective Date: 10-Jun-2003
• Replaced By: ASTM D3739-05 - Standard Practice for Calculation and Adjustment of the Langelier Saturation Index for Reverse Osmosis
• Effective Date: 01-Jan-2005
• Referred By: ASTM D6161-19 - Standard Terminology Used for Microfiltration, Ultrafiltration, Nanofiltration, and Reverse Osmosis Membrane Processes
• Effective Date: 10-Jun-2003
• Referred By: ASTM D4582-23 - Standard Practice for Calculation and Adjustment of the Stiff and Davis Stability Index for Reverse Osmosis
• Effective Date: 10-Jun-2003

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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An American National Standard
Designation:D 3739–94 (Reapproved 2003)
Standard Practice for
Calculation and Adjustment of the Langelier Saturation
Index for Reverse Osmosis
This standard is issued under the fixed designation D 3739; 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.
1. Scope pH, and solution temperature that shows the tendency of a
water solution to precipitate or dissolve calcium carbonate.
1.1 This practice covers the calculation and adjustment of
the Langelier saturation index for the concentrate stream of a
4. Summary of Practice
reverse osmosis device. This index is used to determine the
4.1 This practice consists of calculating the Langelier satu-
need for calcium carbonate scale control in the operation and
ration index for a reverse osmosis concentrate stream from the
design of reverse osmosis installations. This practice is appli-
total dissolved solids, calcium ion content, total alkalinity, pH,
cable for concentrate streams containing up to 10 000 mg/Lof
and temperature of the feed solution, and the recovery of the
total dissolved solids.
reverse osmosis system.
1.2 This standard does not purport to address all of the
4.2 This practice also presents techniques to lower the
safety concerns, if any, associated with its use. It is the
Langelier saturation index by decreasing the recovery, by
responsibility of the user of this standard to establish appro-
decreasing the calcium content of the feedwater, or by chang-
priate safety and health practices and determine the applica-
ing the ratio of total alkalinity to free carbon dioxide in the
bility of regulatory limitations prior to use.
feedwater.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards:
5.1 In the design and operation of reverse osmosis installa-
D 511 Test Methods for Calcium and Magnesium inWater
2 tions, it is important to predict the calcium carbonate scaling
D 1067 Test Methods for Acidity or Alkalinity of Water
properties of the concentrate stream. Because of the increase in
D 1129 Terminology Relating to Water
2 total dissolved solids in the concentrate stream and the differ-
D 1293 Test Method for pH of Water
ence in passages for calcium ion, bicarbonate ion, and free
D 1888 Test Methods for Particulate and Dissolved Matter
3 CO , the calcium carbonate scaling properties of the concen-
in Water
trate stream will generally be quite different from those of the
D 4194 Test Methods for Operating Characteristics of
4 feed solution. This practice permits the calculation of the
Reverse Osmosis Devices
Langelier saturation index for the concentrate stream from the
3. Terminology feed water analyses and the reverse osmosis operating param-
eters.
3.1 For definitions of terms used in this practice, refer to
5.2 A positive Langelier saturation index indicates the
Terminology D 1129.
tendency to form a calcium carbonate scale, which can be
3.2 Definitions of Terms Specific to This Standard:
damaging to reverse osmosis performance. This practice gives
3.2.1 For descriptions of terms relating to reverse osmosis,
various procedures for the adjustment of the Langelier satura-
refer to Test Methods D 4194.
tion index.
3.2.2 Langelier saturation index—an index calculated from
5.3 The tendency to form CaCo scale can be suppressed by
total dissolved solids, calcium concentration, total alkalinity,
the addition of antisealents or crystal modifiers. Suppliers of
antisealents and crystal modifiers can provide information on
This practice is under the jurisdiction of ASTM Committee D19 on Water and
the scale inhibition peformance of these types of chemical.
is the direct responsibility of Subcommittee D19.08 on Membranes and Ion
Their use may be appropriate for reducing scale formation in
Exchange Materials.
ROsystems.TheROsystemsuppliershouldbeconsultedprior
Current edition approved June 10, 2003. Published August 2003. Originally
to the use of antisealents and crystal modifiers to ensure they
approved in 1978. Last previous edition approved in 1998 as D 3739 – 94 (1998).
Annual Book of ASTM Standards, Vol 11.01.
will not have a negative impact on the RO system.
Discontinued—See 1989 Annual Book of ASTM Standards, Vol 11.01.
Annual Book of ASTM Standards, Vol 11.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 3739–94 (2003)
6. Procedure
Y = recovery of the reverse osmosis system, ex-
pressed as a decimal, and
6.1 Determine the calcium concentration in the feed solu-
SP = passage of total dissolved solids, expressed as a
tion in accordance with Test Methods D 511 and express as
TDS
decimal.
CaCO .
6.2 Determine the total dissolved solids of the feed solution
NOTE 2—SPTDS can be obtained from the supplier of the specific
using Test Methods D 1888.
reverse osmosis system. For most reverse osmosis devices SPTDS can be
6.3 Determine the total alkalinity of the feed solution using
assumed to be zero, in which case the equation simplifies to:
Test Methods D 1067, and express as CaCO .
3 TDS 5 TDS 3~1/1 2 Y! (4)
c f
6.4 Measure the pH of the feed solution using Test Method
The error introduced will usually be negligible.
D 1293.
6.5 Measure the temperature of the feed solution.
7.3 Calculate the alkalinity in the concentrate stream from
the alkalinity in the feed solution, the recovery of the reverse
7. Calculation
osmosis system, and the passage of alkalinity, by:
7.1 Calculate the calcium concentration in the concentrate
1 2 Y SP
~ !
alk
Alk 5 Alk 3 (5)
stream from the calcium concentration in the feed solution, the c f
1 2 Y
recovery of the reverse osmosis system, and the calcium ion
passage as follows:
where:
1 2 Y~SP !
Ca
Alk = alkalinity in concentrate, as CaCO , mg/L,
c 3
Ca 5 Ca 3 (1)
c f
1 2 Y
Alk = alkalinity in feed, as CaCO , mg/L,
f 3
Y = recovery of the reverse osmosis system, expressed
as a decimal, and
where:
SP =
...