ASTM D4692-87(1996)

Standard Practice for Calculation and Adjustment of Sulfate Scaling Salts (CaSO₄, SrSO₄, and BaSO₄) for Reverse Osmosis and Nanofiltration

SCOPE
1.1 This practice covers the calculation and adjustment of calcium, strontium, and barium sulfates for the concentrate stream of a reverse-osmosis system. The calculations are used to determine the need for scale control in the operation and design of reverse-osmosis installations. This practice is applicable for all types of reverse osmosis devices (tubular, spiral wound, and hollow fiber).  
1.2 This practice is applicable to both brackish waters and seawaters.

General Information

• Status: Historical
• Publication Date: 09-Jun-2001
• ICS: 71.120.99 - Other equipment for the chemical industry
• Technical Committee: D19 - Water
• Drafting Committee: D19.08 - Membranes and Ion Exchange Materials

Relations

• Replaced By: ASTM D4692-01 - Standard Practice for Calculation and Adjustment of Sulfate Scaling Salts (CaSO₄, SrSO₄, and BaSO₄) for Reverse Osmosis and Nanofiltration
• Effective Date: 10-Jun-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or
withdrawn. Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4692 – 87 (Reapproved 1996)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Practice for
Calculation and Adjustment of Sulfate Scaling Salts (CaSO ,
SrSO , and BaSO ) for Reverse Osmosis
4 4
This standard is issued under the fixed designation D 4692; 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 4.2 This practice also presents techniques to eliminate
++
scaling by decreasing the recovery, by decreasing the Ca ,
1.1 This practice covers the calculation and adjustment of
++ ++
Sr , and Ba concentrations in the feed water, and by
calcium, strontium, and barium sulfates for the concentrate
addition of scale inhibitors.
stream of a reverse osmosis system. The calculations are used
to determine the need for scale control in the operation and
5. Significance and Use
design of reverse osmosis installations. This practice is appli-
cable for all types of reverse osmosis devices (tubular, spiral 5.1 In the design and operation of reverse osmosis
installations, it is important to predict the CaSO , SrSO , and
wound, and hollow fiber).
4 4
BaSO scaling properties of the concentrate stream. Because of
1.2 This practice is applicable to both brackish waters and
seawaters. the increase in total dissolved solids and the increase in
concentration of the scaling salts, the scaling properties of the
2. Referenced Documents
concentrate stream will be quite different from those of the feed
2.1 ASTM Standards: solution. This practice permits the calculation of the scaling
D 511 Test Methods for Calcium and Magnesium in Water
potential for the concentrate stream from the feed water
D 516 Test Method for Sulfate Ion in Water analyses and the reverse osmosis operating parameters.
D 1129 Terminology Relating to Water
5.2 Scaling by CaSO , SrSO , and BaSO will adversely
4 4 4
D 3352 Test Method for Strontium Ion in Brackish Water, affect the reverse osmosis performance. This practice gives
Seawater, and Brines
various procedures for the prevention of scaling.
D 4194 Test Methods for Operating Characteristics of Re-
verse Osmosis Devices 6. Procedure
++ ++ ++
D 4195 Guide for Water Analysis for Reverse Osmosis
6.1 Determine the concentrations of Ca ,Sr ,Ba , and
Application
SO in the feed stream in accordance with Test Methods
D 4382 Test Method for Barium in Water, Atomic Absorp-
D 511, D 3352, D 4382, and D 516, respectively.
tion Spectrophotometry, Graphite Furnace
NOTE 1—If H SO is used for control of CaCO scale, measure the
2 4 3
3. Terminology SO after acid addition.
3.1 Definitions—For definitions of terms used in this prac-
6.2 Determine the concentration of all major ions using the
tice, refer to Terminology D 1129.
appropriate methods given in Guide D 4195. At a minimum,
++ + – −
3.2 Definitions of Terms Specific to This Standard:
the concentrations of Mg ,Na , HCO , and Cl must be
3.2.1 For definitions of terms relating to reverse osmosis,
determined.
refer to Test Methods D 4194.
7. Calculation
4. Summary of Practices
7.1 Calculate the calcium concentration in the concentrate
4.1 This practice consists of calculating the potential for
stream from the calcium concentration in the feed solution,
scaling by CaSO , SrSO , and BaSO in a reverse osmosis
4 4 4
from the recovery of the reverse osmosis system, and from the
++ ++ ++
concentrate stream from the concentration of Ca ,Sr ,Ba ,
calcium ion passage as follows:
and SO in the feed solution and the recovery of the reverse
1 2 Y ~SP !
Ca
osmosis system.
Ca 5 Ca 3
c f
1 2 Y
1 where:
This practice is under the jurisdiction of ASTM Committee D-19 on Water and
Ca 5 calcium ion concentration in concentrate, mg/L,
is the direct responsibility of Subcommittee D 19.08 on Membranes and Ion
c
Exchange Materials. Ca 5 calcium ion concentration in feed, mg/L,
f
Current edition approved May 29, 1987. Published July 1987.
Y 5 recovery of the reverse osmosis system, expressed
Annual Book of ASTM Standards, Vol 11.01.
as a decimal, and
Annual Book of ASTM Standards, Vol 11.02.
D 4692
7.5 Calculate the ion product (IP ) for CaSO in the
SP 5 calcium ion passage, expressed as a decimal.
c 4
Ca
concentrate stream as follows:
NOTE 2—SP can be obtained from the supplier of the reverse osmosis
Ca
m 11 m 5
IP 5 ~ Ca ! ~ SO !
system. For most reverse osmosis devices, SP can be considered to be
c c 4 c
Ca
zero, in which case the equation simplifies to:
where:
1 m ++ ++
( Ca ) 5 M Ca in concentrate, mol/L and
Ca 5 Ca 3 c
c f
1 2 Y
m 5 5
~ SO ) M SO in concentrate, mol/L.
4 c 4
This assumption will introduce only a small error.
7.6 Compare IP for CaSO with the solubility product (
c 4
7.2 Calculate the SO concentration in the concentrate
4 K ) of CaSO at the ionic strength of the concentrate stream
sp 4
stream from
...