ASTM_D_4692_-_01_2010.pdf

Designation:D469201(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 year 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 ofcalcium,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 of 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 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 and Nanofiltration DevicesD4195 Guide for Water Analysis for Reverse Osmosis andNanofiltration ApplicationD4382 Test Method for Barium in Water,AtomicAbsorptionSpectrophotometry,Graphite FurnaceD6161 Terminology Used for Microfiltration,Ultrafiltration,Nanofiltration and Reverse Osmosis Membrane Processes3.Terminology3.1 DefinitionsFor definitions of terms used in thispractice,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 consists of calculating the potential forscaling by CaSO4,SrSO4,and BaSO4in a reverse osmosis ornanofiltration concentrate stream from the concentration ofCa+,Sr+,Ba+,andSO45in the feed solution and the recoveryof the reverse osmosis or nanofiltration system.4.2 This practice also presents techniques 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,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 calculationof 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 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.NOTE1If H2SO4is used for control of CaCO3scale,measure the SO45after acid addition.6.2 Determine the concentration of all major ions using theappropriate methods given in Guide D4195.At a minimum,the1This 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 as D4692 01(2006)1.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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 concentrations of Mg+,Na+,HCO32,and Clmust be deter-mined.7.Calculation7.1 Calculate the calcium concentration in the concentratestream 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 YSPCa!1 2 Ywhere:Cac=calcium ion concentration in concentrate,mg/L,Caf=calcium ion concentration in feed,mg/L,Y=recovery of the reverse osmosis system,expressedas a decimal,andSPCa=calcium ion passage,expressed as a decimal.NOTE2SPCacan be obtained from the supplier of the reverse osmosisor nanofiltration system.For most reverse osmosis and nanofiltrationdevices,SPCacan be considered t