1、Designation: D 6807 02Standard Test Method forOperating Performance of Continuous ElectrodeionizationSystems on Reverse Osmosis Permeates from2 to 100 S/cm1This standard is issued under the fixed designation D 6807; the number immediately following the designation indicates the year oforiginal adopt
2、ion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the oper-ating characterist
3、ics of continuous electrodeionization (CEDI)devices, indicative of deionization performance when a deviceis applied to production of highly deionized water from theproduct water of a reverse osmosis system. This test method isa procedure applicable to feed waters containing carbonic acidand/or disso
4、lved silica and other solutes, with a conductivityrange of approximately 2 to 100 microsiemens-cm-1.1.2 This test method covers the determination of operatingcharacteristics under standard test conditions of CEDI deviceswhere the electrically active transfer media therein is predomi-nantly regenerat
5、ed.1.3 The method is not necessarily indicative of:1.3.1 Long term performance on feed waters containingfoulants and/or sparingly soluble solutes;1.3.2 Performance on feeds of brackish water, sea water, orother high salinity feeds;1.3.3 Performance on synthetic industrial feed solutions,pharmaceutic
6、als, or process solutions of foods and beverages;or,1.3.4 Performance on feed waters less than 2 S/cm, par-ticularly performance relating to organic solutes, colloidal orparticulate matter, or biological or microbial matter.1.4 The test method, subject to the limitations described,can be applied as
7、either an aid to predict expected deionizationperformance for a given feed water quality, or as a method todetermine whether performance of a given device has changedover some period of time. It is ultimately, however, the usersresponsibility to ensure the validity of the test method for theirspecif
8、ic applications.1.5 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of this standard toestablish appropriate safety and health practice
9、s and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 513 Test Methods for Total and Dissolved Carbon Diox-ide in Water (Method A or B)D 859 Test Method for Silica in WaterD 1125 Test Methods for Electrical Conductivity and Re-sistivit
10、y of Water (Method B)D 1129 Terminology Relating to WaterD 1293 Test Methods for pH of Water (Method B)D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D19 on WaterD 4194 Test Methods for Operating Characteristics of Re-verse Osmosis Devices (Method B)3. Term
11、inology3.1 DefinitionsFor definitions of general terms used inthese test methods, refer to Terminology D 1129.3.2 For descriptions of terms relating to reverse osmosis,refer to Test Methods D 4194.3.3 Definitions of Terms Specific to This Standard:3.3.1 cellan independently fed chamber formed by two
12、adjacent ion exchange membranes, or by a membrane and anadjacent electrode.3.3.2 continuous electrodeionization (CEDI) devicea de-vice that removes ionized and ionizable species from liquidsusing electrically active media and using an electrical potentialto influence ion transport, where the ionic t
13、ransport propertiesof the active media are a primary sizing parameter. CEDIdevices typically comprise semi-permeable ion exchangemembranes and permanently charged ion exchange media.Examples include continuous deionization, electrodiaresis, andpacked-bed or filled-cell electrodialysis.3.3.3 current
14、effciencythe ratio, expressed in percent, ofthe net transfer of ionized and ionizable solutes per unit cellwithin a CEDI device, expressed in chemical equivalentstransferred per unit time, to the number of coulombs trans-ferred from an external DC power source to each electrode1This test method is u
15、nder the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.08 on Membranes and IonExchange Materials.Current edition approved June 10, 2002. Published August 2002.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custom
16、er Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.pair, expressed in faradays per unit
17、time. Calculation of currentefficiency is described in 9.2.4. Summary of Test Method4.1 This test method is used to determine performancecapabilities of CEDI devices with regard to extent of ionremoval, pressure/flow relationships and electrical power con-sumption at standard or nominal operating co
18、nditions, electri-cal current characteristics, and the relative ability of the deviceto remove ionized and ionizable species when fed reverseosmosis permeate water. On this type of feed, there is consid-erable water splitting and ion-exchange resin regeneration,causing certain species to become ioni
19、zed within the device,either by the electromotive force or a localized pH shift. Themethod is applicable to both new and used devices.4.2 Pressure loss data is obtained. This information providesinformation relating to possible particulate plugging, fouling,or internal damage of the device. Deioniza
20、tion performance,extent of silica and dissolved carbon dioxide removal, concen-trating stream pH, and applied voltage are determined at apredetermined level of electrical current transfer. The ohmic(electrical) resistance is determined. This information in com-bination with concentrating stream pH p
21、rovides basic designand performance information.5. Significance and Use5.1 CEDI devices can be used to produce deionized waterfrom feeds of pretreated water. This test method permits themeasurement of key performance capabilities of CEDI devicesusing a standard set of conditions. The data obtained c
22、an beanalyzed to provide information on whether changes may haveoccurred in operating characteristics of the device indepen-dently of any variability in feed water characteristics oroperating conditions. Under specific circumstances, the methodmay also provide sufficient information for plant design
23、.6. Apparatus6.1 Description:6.1.1 The test apparatus is schematically represented in Fig.1. Feed water to the apparatus may be passed through a heatexchanger and/or other accessories to modify and/or controlfeed water temperature as desired. Alternately, data obtainedfrom the operation of the appar
24、atus may be normalized fortemperature if normalization factors are known.6.1.2 Feed water to the apparatus enters a holding tank(open or vented) of volume sufficient to maintain good controlof water level and solute concentrations. The tank is unpres-surized, ported to be capable of occasional clean
25、ings orsanitizations, and incorporates needed safety features such ashigh temperature and overflow protection. The tank alsoincorporates a drain valve. During operation of the apparatus,the drain valve may be used in combination with a valvecontrolling the rate of feed water to the apparatus to aid
26、incontrol of solute concentrations, water level, and temperaturewithin the tank. The tank supplies water to a recirculationpump designed to feed water to the CEDI device at a flow rateand pressure consistent with the ratings of the CEDI device. Arecirculation line with shut off valve from the pump d
27、ischargeto the tank may be incorporated as required for proper pumpoperation.6.1.3 Adjustment of feed water solute concentration is notrequired.Adjust feed water pH as required by the manufacturerof the CEDI device. Feed water to the CEDI device must bemonitored for solute concentrations, pH (Test M
28、ethod D 1293),and temperature. Solute concentration may be monitored viaelectrical conductivity or resistivity (Test Method D 1125)incombination with silica (Test Method D 513) and carbondioxide (Test Method D 859) concentration measurement, oralternately may be monitored for individual ionic specie
29、s anddissolved carbon dioxide and silica, depending on the feedwater supplied to the tank and the solutes of interest.6.1.4 Feed water provided to the CEDI device should beplumbed as specified by the supplier, with appropriate flow andpressure controls, internal recirculations, drains, interlocks,sa
30、fety controls, and other features as required. Pressure at theinlet and outlet and flow rates of each the streams of interestmust be monitored (for example, deionized water stream,concentrate stream, and electrode feed stream).6.1.5 The CEDI device should be powered as specified bythe supplier, with
31、 equipment and wiring to provide appropriatesupply DC voltage and amperage, controls, interlocks, ground-ing, and safety features. Supply voltage and supply amperageto the CEDI device should be monitored at positions within thedevice or device assembly as specified by the supplier.6.1.6 Streams leav
32、ing the CEDI device may be returned tothe tank via return lines.Alternately, one or more of the streamsmay be sent either completely or partially to drain viaappropriate valving if such operation provides easier control ofdesired feed water conditions. The outlet deionization stream ismonitored for
33、the same solutes as for the feed water. The outletconcentrating stream is also monitored for the same solutes asfor the feed water. Control of temperature is not required. ForCEDI devices with internal recirculation and “feed and bleed”features, solute concentrations must be measured at locationstha
34、t are indicative of conditions within the CEDI module priorto mixing of recirculation flows.6.1.7 Feed water to the tank of the test apparatus shall beprepared using reverse osmosis apparatus. The pretreatmentrequirements for the RO are optional depending on theapplication, but should, at minimum, c
35、onform to the manufac-turers specifications for the particular system.6.2 Installation:6.2.1 Materials of construction shall be as specified by thesupplier of the CEDI device and in conformance to standardengineering practice.6.2.2 Controls and monitors should be calibrated and main-tained according
36、 with suppliers requirements and standardengineering practice.7. Reagents7.1 Specific chemical reagents are not required for this testmethod. However, chemical modification such as pH adjust-ment, addition of trace solutes, and the addition of dissolvedcarbon dioxide may be applicable under certain
37、circumstances.Unless otherwise indicated, it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalD6807022FIG.1ProcessFlowSchematicD6807023Reagents of the American Chemical Society, where suchspecifications are available.3Other grades may be used, pro-vided
38、it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8. Procedure8.1 Start Up:8.1.1 Ensure that the tank and reagent feed reservoirs aresufficiently full, with adequate feed water rate to accommodateany losses of
39、water caused by the positioning of the variousdrain valves. Control valves to the CEDI device should beclosed and the device should be unpowered.8.1.2 Turn on the recirculation pump and then slowly openthe feed water throttling valves and various valves and recir-culation devices on the CEDI device
40、until the device isoperating at nominal or supplier recommended flow condi-tions. Modify throttling valves to adjust inlet and outletpressures of the various device streams in accordance withsupplier recommendations.8.1.3 Operate the system with no DC power applied for asufficient time to ensure ade
41、quate removal of any residual airfrom the piping and device. During this time, flows, pressures,feed solute concentrations, and temperature, should be adjusteduntil a desirable steady state device feed water condition hasbeen attained.8.2 Electrical Property and Deionization PerformanceMeasurements:
42、8.2.1 Turn on the DC power supply to the CEDI device,beginning at a low voltage. Raise the applied DC voltage untilDC amperage between electrode pairs attains a pre-determinedelectrical current efficiency, typically below 20 %, but do notapply a voltage or amperage that exceeds suppliers recom-menda
43、tions (consult supplier for recommended values). Cur-rent efficiency should be calculated as described in 9.2 using asNdi the total combined normality of all ionized and ionizableconstituents (for example, including all ionized species, anddissolved carbon dioxide as monovalent bicarbonate ion anddi
44、ssolved silica as monovalent bisilicate ion).8.2.2 As the internal media electroregenerates, pH shifts andnon-steady state concentrate concentrations should be ex-pected. Therefore, recirculation flows, flows to drain, andvoltage should be controlled so as to avoid exceeding suppli-ers recommended o
45、perating parameters and to speed theattainment of steady state conditions.8.2.3 Continue to operate until steady state is achieved,including applied voltage, concentrate stream electrical con-ductivity, deionization performance, silica and carbon dioxideconcentrations at the deionizing and concentra
46、ting streamoutlets, and deionizing and concentrating stream flows andinlet and outlet pressures. Since electroregeneration of theactive media can be a gradual process, it will typically take 4to8htoreach steady state. Pressures should be expected tochange as the internal media electroregenerates. Do
47、 not exceedsuppliers specifications for pressure differentials.8.2.4 Measure and record DC voltage, DC amperage, devicefeed water temperature, deionizing stream inlet and outletconductivity or resistivity, and deionizing stream flow rate.Also, measure and record feed pH, feed and deionizing streaman
48、d concentrating stream outlet silica and carbon dioxideconcentrations. Attachment A is a sample test data sheet.NOTE 1In RO permeates, dissolved CO2often comprises the majorityof ionized and ionizable material present, and the CO2concentration canvary greatly depending upon the pH of the RO feed wat
49、er. Since it may notbe practical to control the CO2concentration feeding the CEDI device, itis very important that the feed CO2be measured when this test isperformed.8.3 Pressure Drop MeasurementsOnce steady state isachieved, as described in 8.2, measure and record pressures ofthe various inlet and outlet streams of the device. If necessary,normalize pressure differentials for temperature and compareto suppliers specifications.8.4 Shut Down ProcedureThe CEDI system should beshut down in accordance with the manufacturers recommen-dations. If no specific recommendations
