ASTM D4692-01(2017)

Standard Practice for Calculation and Adjustment of Sulfate Scaling Salts (CaSO<inf >4</inf>, SrSO<inf>4</inf>, and BaSO<inf>4</inf>) for Reverse Osmosis and Nanofiltration

SIGNIFICANCE AND USE
5.1 In the design and operation of reverse osmosis and nanofiltration installations, it is important to predict the CaSO4, SrSO4, and BaSO4 scaling properties of the concentrate stream. Because of the increase in total dissolved solids and the increase in concentration of the scaling salts, the scaling properties of the concentrate stream will be quite different from those of the feed solution. This practice permits the calculation of the scaling potential for the concentrate stream from the feed water analyses and the reverse osmosis or nanofiltration operating parameters.  
5.2 Scaling by CaSO4, SrSO4, and BaSO4 will adversely affect the reverse osmosis or nanofiltration performance. This practice gives various procedures for the prevention of scaling.
SCOPE
1.1 This practice covers the calculation and adjustment of calcium, strontium, and barium sulfates for the concentrate stream of a reverse osmosis or nanofiltration system. The calculations are used to determine the need for scale control in the operation and design of reverse osmosis and nanofiltration installations. This practice is applicable for all types of reverse osmosis devices (tubular, spiral wound, and hollow fiber) and nanofiltration devices.  
1.2 This practice is applicable to both brackish waters and seawaters.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 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.

General Information

• Status: Published
• Publication Date: 30-Nov-2017
• ICS: 71.120.99 - Other equipment for the chemical industry
• Technical Committee: D19 - Water
• Drafting Committee: D19.08 - Membranes and Ion Exchange Materials

Relations

• Replaces: ASTM D4692-01(2010) - Standard Practice for Calculation and Adjustment of Sulfate Scaling Salts (CaSO₄, SrSO₄, and BaSO₄) for Reverse Osmosis and Nanofiltration
• Effective Date: 01-Dec-2017
• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D6161-19 - Standard Terminology Used for Microfiltration, Ultrafiltration, Nanofiltration, and Reverse Osmosis Membrane Processes
• Effective Date: 01-Jul-2019
• Refers: ASTM D4382-18 - Standard Test Method for Barium in Water, Atomic Absorption Spectrophotometry, Graphite Furnace
• Effective Date: 01-Feb-2018
• Refers: ASTM D3352-15 - Standard Test Method for Strontium Ion in Brackish Water, Seawater, and Brines
• Effective Date: 01-Feb-2015
• Refers: ASTM D4382-12 - Standard Test Method for Barium in Water, Atomic Absorption Spectrophotometry, Graphite Furnace
• Effective Date: 01-Sep-2012
• Refers: ASTM D516-11 - Standard Test Method for Sulfate Ion in Water
• Effective Date: 01-Sep-2011
• Refers: ASTM D1129-10 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2010
• Refers: ASTM D6161-10 - Standard Terminology Used for Microfiltration, Ultrafiltration, Nanofiltration and Reverse Osmosis Membrane Processes (Withdrawn 2019)
• Effective Date: 01-Feb-2010
• Refers: ASTM D511-09 - Standard Test Methods for Calcium and Magnesium In Water
• Effective Date: 01-May-2009
• Refers: ASTM D3352-08a - Standard Test Method for Strontium Ion in Brackish Water, Seawater, and Brines
• Effective Date: 15-Nov-2008
• Refers: ASTM D511-08 - Standard Test Methods for Calcium and Magnesium In Water
• Effective Date: 01-Oct-2008
• Refers: ASTM D3352-08 - Standard Test Method for Strontium Ion in Brackish Water, Seawater, and Brines
• Effective Date: 15-Aug-2008
• Refers: ASTM D4194-03(2008) - Standard Test Methods for Operating Characteristics of Reverse Osmosis and Nanofiltration Devices
• Effective Date: 01-May-2008
• Refers: ASTM D4195-08 - Standard Guide for Water Analysis for Reverse Osmosis and Nanofiltration Application
• Effective Date: 01-May-2008

Overview

ASTM D4692-01(2017), issued by ASTM International, is the standard practice for the calculation and adjustment of sulfate scaling salts-including calcium sulfate (CaSO₄), strontium sulfate (SrSO₄), and barium sulfate (BaSO₄)-in reverse osmosis (RO) and nanofiltration (NF) systems. The purpose of this standard is to predict and control the scaling potential of these salts, which can accumulate and impair the performance of membrane filtration installations.

This practice serves as a crucial reference for water treatment professionals concerned with optimizing the operation and design of RO and NF systems, particularly those processing brackish water and seawater. Correctly managing sulfate scaling is essential for maximizing water recovery, minimizing maintenance, and ensuring consistent water quality.

Key Topics

• Scaling Salt Calculation: The standard details methods for calculating concentrations of CaSO₄, SrSO₄, and BaSO₄ in the concentrate stream based on feed water analysis and system recovery rates.
• Scaling Potential Assessment: Procedures are provided to evaluate the risk of membrane scaling using the calculated concentrations of key ions and solubility product values.
• Adjustment Techniques for Scale Control:
  • System recovery modification
  • Source water pretreatment (including ion exchange)
  • Chemical addition, such as scale inhibitors
  • Process parameter adjustments
• Applicability: Guidance covers all types of reverse osmosis devices (tubular, spiral wound, hollow fiber) and nanofiltration units operating with a variety of feed waters.
• Measurement Procedures: The standard references established ASTM methods for analyzing calcium, strontium, barium, and sulfate ions, ensuring consistency and accuracy in scaling assessments.

Applications

Water Treatment System Design

• Pre-installation Planning: Predicting scaling risk from sulfate salts is essential for selecting appropriate membranes, designing recovery rates, and specifying water treatment processes.
• Reducing Operational Downtime: Proper scaling calculation and adjustment enable longer membrane life and reduce the frequency of system cleaning and replacement, lowering costs and improving reliability.
• Optimizing Recovery Rates: By understanding and controlling scaling limits, operators can safely maximize the water recovery from brackish water or seawater, improving efficiency and overall system capacity.

Process Control and Maintenance

• Ongoing Monitoring: During system operation, the standard supports routine assessment of the concentrate stream, comparing actual measurements with calculated values for proactive scale management.
• Troubleshooting: If performance drops or scaling occurs, ASTM D4692 guides adjustments to operating conditions or chemical dosing to resolve issues swiftly and effectively.

Industry and Regulatory Compliance

• International Relevance: Developed according to World Trade Organization TBT principles, this standard aids organizations in meeting quality and performance targets consistent with global best practices.
• Broad Industry Use: Applicable in municipal water treatment, industrial process water reuse, desalination plants, and other sectors employing membrane separation technologies.

Related Standards

For comprehensive sulfate scaling management in membrane filtration, reference the following ASTM standards:

• ASTM D511 – Test Methods for Calcium and Magnesium in Water
• ASTM D516 – Test Method for Sulfate Ion in Water
• ASTM D3352 – Test Method for Strontium Ion in Brackish Water, Seawater, and Brines
• ASTM D4382 – Test Method for Barium in Water (Atomic Absorption Spectrophotometry)
• ASTM D4194 – Test Methods for Operating Characteristics of Reverse Osmosis and Nanofiltration Devices
• ASTM D4195 – Guide for Water Analysis for Reverse Osmosis and Nanofiltration Application
• ASTM D6161 – Terminology used for Microfiltration, Ultrafiltration, Nanofiltration, and Reverse Osmosis Membrane Processes

Keywords: sulfate scaling, membrane fouling, reverse osmosis, nanofiltration, calcium sulfate, strontium sulfate, barium sulfate, water treatment, scale inhibitor, ASTM D4692

Standards Content (Sample)

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: D4692 −01 (Reapproved 2017)
Standard Practice for
Calculation and Adjustment of Sulfate Scaling Salts (CaSO ,
SrSO , and BaSO ) for Reverse Osmosis and Nanofiltration
4 4
This standard is issued under the fixed designation D4692; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D4382TestMethodforBariuminWater,AtomicAbsorption
Spectrophotometry, Graphite Furnace
1.1 This practice covers the calculation and adjustment of
D6161TerminologyUsedforMicrofiltration,Ultrafiltration,
calcium, strontium, and barium sulfates for the concentrate
Nanofiltration and Reverse Osmosis Membrane Processes
stream of a reverse osmosis or nanofiltration system. The
calculations are used to determine the need for scale control in
3. Terminology
the operation and design of reverse osmosis and nanofiltration
3.1 Definitions:
installations.This practice is applicable for all types of reverse
3.1.1 For definitions of terms used in this standard, refer to
osmosis devices (tubular, spiral wound, and hollow fiber) and
Terminologies D1129 and D6161.
nanofiltration devices.
3.2 Definitions of Terms Specific to This Standard:
1.2 This practice is applicable to both brackish waters and
3.2.1 For definitions of terms relating to reverse osmosis,
seawaters.
refer to Test Methods D4194.
1.3 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 This practice consists of calculating the potential for
1.4 This international standard was developed in accor-
scaling by CaSO , SrSO , and BaSO in a reverse osmosis or
4 4 4
dance with internationally recognized principles on standard-
nanofiltration concentrate stream from the concentration of
ization established in the Decision on Principles for the
++ ++ ++
Ca ,Sr ,Ba ,and SO inthefeedsolutionandtherecovery
Development of International Standards, Guides and Recom-
of the reverse osmosis or nanofiltration system.
mendations issued by the World Trade Organization Technical
4.2 This practice also presents techniques to eliminate
Barriers to Trade (TBT) Committee.
++
scaling by decreasing the recovery, by decreasing the Ca ,
++ ++
2. Referenced Documents
Sr , and Ba concentrations in the feed water, and by
addition of scale inhibitors.
2.1 ASTM Standards:
D511Test Methods for Calcium and Magnesium In Water
5. Significance and Use
D516Test Method for Sulfate Ion in Water
5.1 In the design and operation of reverse osmosis and
D1129Terminology Relating to Water
D3352Test Method for Strontium Ion in Brackish Water, nanofiltrationinstallations,itisimportanttopredicttheCaSO ,
SrSO ,andBaSO scalingpropertiesoftheconcentratestream.
Seawater, and Brines
4 4
D4194Test Methods for Operating Characteristics of Re- Because of the increase in total dissolved solids and the
increase in concentration of the scaling salts, the scaling
verse Osmosis and Nanofiltration Devices
D4195Guide for Water Analysis for Reverse Osmosis and propertiesoftheconcentratestreamwillbequitedifferentfrom
thoseofthefeedsolution.Thispracticepermitsthecalculation
Nanofiltration Application
ofthescalingpotentialfortheconcentratestreamfromthefeed
water analyses and the reverse osmosis or nanofiltration
This practice is under the jurisdiction ofASTM Committee D19 on Water and
operating parameters.
is the direct responsibility of Subcommittee D19.08 on Membranes and Ion
Exchange Materials.
5.2 Scaling by CaSO , SrSO , and BaSO will adversely
4 4 4
Current edition approved Dec. 1, 2017. Published December 2017. Originally
affect the reverse osmosis or nanofiltration performance. This
approved in 1987. Last previous edition approved in 2010 as D4692–01 (2010).
practicegivesvariousproceduresforthepreventionofscaling.
DOI: 10.1520/D4692-01R17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6. Procedure
Standards volume information, refer to the standard’s Document Summary page on
++ ++ ++
the ASTM website. 6.1 Determine the concentrations of Ca ,Sr ,Ba , and
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4692 − 01 (2017)
SO in the feed stream in accordance withTest Methods D511, 7.5 Calculate the ion product (IP ) for CaSO in the
4 c 4
D3352, D4382, and D516, respectively. concentrate stream as follows:
NOTE1—IfH SO isusedforcontrolofCaCO scale,measuretheSO
2 4 3 4 m 11 m 5
IP 5 Ca SO
~ ! ~ !
c 4
c c
after acid addition.
6.2 Determine the concentration of all major ions using the where:
m ++ ++
appropriatemethodsgiveninGuideD4195.Ataminimum,the
( Ca ) = M Ca in concentrate, mol/L and
c
++ + −
m 5 5
concentrations of Mg ,Na , HCO , and Cl must be deter-
~ SO ! = M SO in concentrate, mol/L.
3 4 4
c
mined.
7.6 Compare IP forCaSO withthesolubilityproduct(K )
c 4 sp
of CaSO at the ionic strength of the concentrate stream (Fig.
7. Calculation 3
1). If IP > K , CaSO scaling will occur and adjustment is
c sp 4
7.1 Calculate the calcium concentration in the concentrate required.
stream from the calcium concentration in the feed solution,
NOTE4—Somesuppliersuseasafetyfactor.Checkwiththesupplierof
from the recovery of the reverse osmosis or nanofiltration
the reverse osmosis or nanofiltration device to determine if some fraction
system, and from the calcium ion passage as follows:
of the K , for example 0.8 K , should be used to compare with IP .
sp sp c
1 2 Y ~SP ! 7.7 Determine the scaling potential for SrSO using the
Ca 4
Ca 5 Ca 3
c f
1 2 Y a
...