ASTM D3739-19

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D3739 − 19
Standard Practice for
Calculation and Adjustment of the Langelier Saturation
Index for Reverse Osmosis
This standard is issued under the fixed designation D3739; 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 D1888 MethodsOfTestforParticulateandDissolvedMatter
in Water (Withdrawn 1989)
1.1 This practice covers the calculation and adjustment of
D4194 Test Methods for Operating Characteristics of Re-
the Langelier saturation index for the concentrate stream of a
verse Osmosis and Nanofiltration Devices
reverse osmosis (RO) device. This index is used to determine
D4195 Guide for Water Analysis for Reverse Osmosis and
the need for calcium carbonate (CaCo ) scale control in the
Nanofiltration Application
operation and design of RO installations. This practice is
D4582 Practice for Calculation and Adjustment of the Stiff
applicable for concentrate streams containing 10 to 10 000
and Davis Stability Index for Reverse Osmosis (With-
mg/Lof total dissolved solids. For concentrate containing over
drawn 2019)
10 000 mg⁄L, see Practice D4582.
D6161 Terminology Used for Microfiltration, Ultrafiltration,
1.2 The values stated in SI units are to be regarded as
Nanofiltration,andReverseOsmosisMembraneProcesses
standard. No other units of measurement are included in this
3. Terminology
standard.
3.1 Definitions:
1.3 This standard does not purport to address all of the
3.1.1 For definitions of terms used in this standard, refer to
safety concerns, if any, associated with its use. It is the
Terminologies D1129 and D6161.
responsibility of the user of this standard to establish appro-
3.1.2 For descriptions of terms relating to RO, refer to Test
priate safety, health, and environmental practices and deter-
Methods D4194.
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
3.2 Definitions of Terms Specific to This Standard:
dance with internationally recognized principles on standard-
3.2.1 Langelier saturation index, n—an index calculated
ization established in the Decision on Principles for the
from total dissolved solids, calcium concentration, total
Development of International Standards, Guides and Recom-
alkalinity, pH, and solution temperature that shows the ten-
mendations issued by the World Trade Organization Technical
dency of a water solution to precipitate or dissolve calcium
Barriers to Trade (TBT) Committee.
carbonate.
2. Referenced Documents
4. Summary of Practice
2.1 ASTM Standards:
4.1 This practice consists of calculating the Langelier satu-
D511 Test Methods for Calcium and Magnesium In Water ration index for a RO concentrate stream from the total
D1067 Test Methods for Acidity or Alkalinity of Water
dissolved solids, calcium ion content, total alkalinity, pH, and
D1129 Terminology Relating to Water temperature of the feed solution, and the recovery of the RO
D1293 Test Methods for pH of Water system.
4.2 This practice also presents techniques to lower the
Langelier saturation index by decreasing the recovery, by
decreasing the calcium content of the feedwater, or by chang-
ing the ratio of total alkalinity to free carbon dioxide (CO)in
This practice is under the jurisdiction of ASTM Committee D19 on Water and
the feedwater.
is the direct responsibility of Subcommittee D19.08 on Membranes and Ion
Exchange Materials.
5. Significance and Use
Current edition approved July 1, 2019. Published July 2019. Originally approved
in 1978. Last previous edition approved in 2010 as D3739 – 06 (2010), which was
5.1 In the design and operation of RO installations, it is
withdrawn January 2019 and reinstated in July 2019. DOI: 10.1520/D3739-19.
importanttopredictthecalciumcarbonatescalingpropertiesof
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
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D3739 − 19
the concentrate stream. Because of the increase in total 1 2 Y SP
~ !
Ca
Ca 5 Ca 3 (3)
c f
dissolved solids in the concentrate stream and the difference in 1 2 Y
passages for calcium ion, bicarbonate ion, and free carbon
where:
dioxide, the calcium carbonate scaling properties of the con-
Ca = calcium concentration in concentrate, as CaCO ,
c 3
centrate stream will generally be quite different from those of
mg/L,
the feed solution. This practice permits the calculation of the
Ca = calcium concentration in feed, as CaCO , mg/L,
f 3
Langelier saturation index for the concentrate stream from the
Y = recovery of the RO system, expressed as a decimal,
feed water analyses and the RO operating parameters.
and
5.2 A positive Langelier saturation index indicates the
SP = calcium ion passage, expressed as a decimal.
Ca
tendency to form a calcium carbonate scale, which can be
NOTE 1—SP can be obtained from the supplier of the specific RO
Ca
damaging to RO performance. This practice gives various
system. For most RO devices, SP can be considered to be zero, in which
Ca
procedures for the adjustment of the Langelier saturation
case the equation simplifies to:
index.
Ca 5 Ca 3 ~1/1 2 Y! (4)
c f
5.3 The tendency to form calcium carbonate scale can be
This assumption will introduce only a small error.
suppressed by the addition of antiscalents or crystal modifiers.
7.2 Calculate the total dissolved solids (TDS) in the con-
Suppliers of antisealents and crystal modifiers can provide
centrate stream from the total dissolved solids in the feed
information on the scale inhibition peformance of these types
solution, the recovery of the RO system, and the passage of
of chemical. Their use may be appropriate for reducing scale
total dissolved solids as follows:
formation in RO systems. The RO system supplier should be
consulted prior to the use of antisealents and crystal modifiers
1 2 Y SP
~ !
TDS
TDS 5 TDS 3 (5)
c f
to ensure they will not have a negative impact on the RO
1 2 Y
system.
where:
6. Procedure
TDS = concentration of total dissolved solids in
c
6.1 Determine the calcium concentration in the feed solu- concentrate, mg/L,
tion in accordance with Test Methods D511 and express as TDS = concentration of total dissolved solids in the feed,
f
CaCO as demonstrated in 6.6.
mg/L,
Y = recovery of the RO system, expressed as a decimal,
6.2 Determine the total dissolved solids of the feed solution
and
using Methods of Test D1888.
SP = passage of total dissolved solids, expressed as a
TDS
6.3 Determine the total alkalinity of the feed so
...