1、Designation: D4692 01 (Reapproved 2010)Standard Practice forCalculation and Adjustment of Sulfate Scaling Salts (CaSO4,SrSO4, and BaSO4) for Reverse Osmosis and Nanofiltration1This standard is issued under the fixed designation D4692; the number immediately following the designation indicates the ye
2、ar oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the calculation and adjustment of
3、calcium, strontium, and barium sulfates for the concentratestream of a reverse osmosis or nanofiltration system. Thecalculations are used to determine the need for scale control inthe operation and design of reverse osmosis and nanofiltrationinstallations. This practice is applicable for all types o
4、f reverseosmosis devices (tubular, spiral wound, and hollow fiber) andnanofiltration devices.1.2 This practice is applicable to both brackish waters andseawaters.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.2. Referenced
5、Documents2.1 ASTM Standards:2D511 Test Methods for Calcium and Magnesium In WaterD516 Test Method for Sulfate Ion in WaterD1129 Terminology Relating to WaterD3352 Test Method for Strontium Ion in Brackish Water,Seawater, and BrinesD4194 Test Methods for Operating Characteristics of Re-verse Osmosis
6、and Nanofiltration DevicesD4195 Guide for Water Analysis for Reverse Osmosis andNanofiltration ApplicationD4382 Test Method for Barium in Water, Atomic Absorp-tion Spectrophotometry, Graphite FurnaceD6161 Terminology Used for Microfiltration, Ultrafiltra-tion, Nanofiltration and Reverse Osmosis Memb
7、rane Pro-cesses3. Terminology3.1 DefinitionsFor definitions of terms used in this prac-tice, refer to Terminology D1129 and D6161.3.2 Definitions of Terms Specific to This StandardFordefinitions of terms relating to reverse osmosis, refer to TestMethods D4194.4. Summary of Practice4.1 This practice
8、consists of calculating the potential forscaling by CaSO4, SrSO4, and BaSO4in a reverse osmosis ornanofiltration concentrate stream from the concentration ofCa+,Sr+,Ba+, and SO45in the feed solution and therecovery of the reverse osmosis or nanofiltration system.4.2 This practice also presents techn
9、iques to eliminatescaling by decreasing the recovery, by decreasing the Ca+,Sr+, and Ba+concentrations in the feed water, and byaddition of scale inhibitors.5. Significance and Use5.1 In the design and operation of reverse osmosis andnanofiltration installations, it is important to predict the CaSO4
10、,SrSO4, and BaSO4scaling properties of the concentrate stream.Because of the increase in total dissolved solids and theincrease in concentration of the scaling salts, the scalingproperties of the concentrate stream will be quite different fromthose of the feed solution. This practice permits the cal
11、culation1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.08 on Membranes and IonExchange Materials.Current edition approved May 1, 2010. Published May 2010. Originallyapproved in 1987. Last previous edition approved in 2006 a
12、s D4692 01 (2006)e1.DOI: 10.1520/D4692-01R10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM
13、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.of the scaling potential for the concentrate stream from the feedwater analyses and the reverse osmosis or nanofiltrationoperating parameters.5.2 Scaling by CaSO4, SrSO4, and BaSO4will adverselyaffect
14、the reverse osmosis or nanofiltration performance. Thispractice gives various procedures for the prevention of scaling.6. Procedure6.1 Determine the concentrations of Ca+,Sr+,Ba+, andSO45in the feed stream in accordance with Test Methods D511,D3352, D4382, and D516, respectively.NOTE 1If H2SO4is use
15、d for control of CaCO3scale, measure theSO45after acid addition.6.2 Determine the concentration of all major ions using theappropriate methods given in Guide D4195.At a minimum, theconcentrations of Mg+,Na+, HCO3, and Clmust bedetermined.7. Calculation7.1 Calculate the calcium concentration in the c
16、oncentratestream from the calcium concentration in the feed solution,from the recovery of the reverse osmosis or nanofiltrationsystem, and from the calcium ion passage as follows:Cac5 Caf31 2 Y SPCa!1 2 Ywhere:Cac= calcium ion concentration in concentrate, mg/L,Caf= calcium ion concentration in feed
17、, mg/L,Y = recovery of the reverse osmosis system, expressedas a decimal, andSPCa= calcium ion passage, expressed as a decimal.NOTE 2SPCacan be obtained from the supplier of the reverse osmosisor nanofiltration system. For most reverse osmosis and nanofiltrationdevices, SPCacan be considered to be z
18、ero, in which case the equationsimplifies to:Cac5 Caf311 2 YThis assumption will introduce only a small error.7.2 Calculate the SO45concentration in the concentratestream from the SO45concentration in the feed solution, fromthe recovery of the reverse osmosis or nanofiltration system,and from the su
19、lfate ion passage by using the appropriatesubstitutions in the equation given in 7.1. The simplifiedequation can be used.7.3 Calculate the concentration of the major ions in theconcentrate stream using the appropriate substitutions in theequation given in 7.1. The simplified equation can be used.7.4
20、 Calculate the ionic strength of the concentrate stream asfollows:Ic512( miZi2where:Ic= ionic strength of concentrate stream,mi= molal concentration of ion, i (moles/1000 g ofwater) in the concentrate stream, andZi= ionic charge of ion, i.NOTE 3The molal concentration is calculated as follows:mi5Ci1
21、000 MWiF1062 TDS106 G51000 CiMWi1062 TDS!where:Ci= concentration of ion, i, in concentrate stream, mg/L,MWi= molecular weight of ion, i, andTDS = total dissolved solids in concentrate stream, mg/L.7.5 Calculate the ion product (IPc) for CaSO4in theconcentrate stream as follows:IPc5 mCa11!cmSO45!cwhe
22、re:(mCa+)c= M Ca+in concentrate, mol/L andmSO45)c= M SO45in concentrate, mol/L.7.6 Compare IPcfor CaSO4with the solubility product (Ksp) of CaSO4at the ionic strength of the concentrate stream(Fig. 1).3If IPc Ksp, CaSO4scaling will occur and adjust-ment is required.NOTE 4Some suppliers use a safety
23、factor. Check with the supplier ofthe reverse osmosis or nanofiltration device to determine if some fractionof the Ksp, for example 0.8 Ksp, should be used to compare with IPc.7.7 Determine the scaling potential for SrSO4using theappropriate substitution in steps 7.1 to 7.4. Compare IPcforSrSO4with
24、the Kspof SrSO4at the ionic strength of theconcentrate stream (Fig. 2).47.8 Determine the scaling potential for BaSO4using theappropriate substitutions in steps 7.1-7.4. Compare IPcforBaSO4with the Kspof BaSO4at the ionic strength of theconcentrate stream (Fig. 3).48. Adjustments for Scale Control8.
25、1 If the IPcfor CaSO4, SrSO4, and BaSO4is less than theKspor the recommended fraction of Ksp, a higher recovery canbe used with respect to scaling by the various salts. Reiterationof the calculations at higher recovery can be used to determinethe maximum conversion with respect to scaling by the var
26、ioussalts.8.2 If the IPcfor CaSO4, SrSO4, or BaSO4is greater thanthe Kspof the recommended fraction of Ksp, a lower recoverymust be used to prevent scaling. Reiteration of the calculationsat lower recovery can be used to determine the allowablerecovery with respect to scaling by the various salts.8.
27、3 If the maximum allowable recovery is lower thandesired, sodium cycle ion exchange (softening) can be used toremove all or part of the Ca+,Sr+, and Ba+. This will permithigher recovery of the reverse osmosis or nanofiltration systemwith respect to scaling by the various salts.3Marshall, W. L. and S
28、lusher, R., “Solubility to 200C of Sulfate and itsHydrates in Sea Water and Saline Water Concentrates and Temperature, Concen-tration Limits,”Journal of Chemical and Engineering Data, Vol 13, No. 1, 1968, p.83.4Davis, J. W. and Collins, A. G., “Solubility of Barium and Strontium Sulfatesin Strong El
29、ectrolyte Solutions,” Environmental Science and Technology, Vol 5, No.10, 1971, p. 1039.D4692 01 (2010)28.4 Lime softening with lime or lime plus soda ash willdecrease the Ca+concentration and thus permit higher con-version with respect to scaling by CaSO4.8.5 Addition of a scale inhibitor to the fe
30、ed stream permitsoperation of the reverse osmosis or nanofiltration system abovethe Kspvalue. Check with supplier of the reverse osmosis orFIG. 1 Kspfor CaSO4versus Ionic StrengthFIG. 2 Kspfor SrSO4versus Ionic StrengthD4692 01 (2010)3nanofiltration system to determine compatibility of inhibitors,co
31、ncentration of the inhibitor needed, and amount by which theKspcan be exceeded when a scale inhibitor is used.9. Reverse Osmosis or Nanofiltration in Operation9.1 Once a reverse osmosis or nanofiltration system isoperating, the scaling potential of CaSO4, SrSO4, and BaSO4can be directly calculated f
32、rom the analyses of the concentratestream and compared with the projected scaling potentialcalculated above.10. Use of Computers for the Determination of ScalingPotential10.1 The preceding calculations are adaptable to simplecomputer analysis.11. Keywords11.1 barium; calcium; membrane fouling; membr
33、ane scal-ing; nanofiltration; reverse osmosis; strontium; sulfate scalingASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity o
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36、ceived a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies)
37、 of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).FIG. 3 Kspfor BaSO4versus Ionic StrengthD4692 01 (2010)4
