ASTM D6529-22

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: D6529 −22
Standard Test Method for
Operating Performance of Continuous Electrodeionization
Systems on Feeds from 50 µS⁄cm to 1000 µS/cm
This standard is issued under the fixed designation D6529; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
1.1 This test method covers the determination of the oper-
standard.
ating characteristics of continuous electrodeionization (CEDI)
1.6 This standard does not purport to address all of the
devices using synthetic feed solutions and is not necessarily
safety concerns, if any, associated with its use. It is the
applicable to natural waters. This test method is a procedure
responsibility of the user of this standard to establish appro-
applicable to solutions with a conductivity range from approxi-
priate safety, health, and environmental practices and deter-
mately 50 µS⁄cm to 1000 µS⁄cm.
mine the applicability of regulatory limitations prior to use.
1.2 This test method covers the determination of operating
1.7 This international standard was developed in accor-
characteristics under standard test conditions of CEDI devices
dance with internationally recognized principles on standard-
where the electrically active transfer media therein is predomi-
ization established in the Decision on Principles for the
nantly unregenerated. This results in more rapid achievement
Development of International Standards, Guides and Recom-
of steady state and shorter test time than when performing a
mendations issued by the World Trade Organization Technical
test which requires the active media be predominantly regen-
Barriers to Trade (TBT) Committee.
erated.
2. Referenced Documents
1.3 This test method is not necessarily indicative of the
2.1 ASTM Standards:
following:
D1125 Test Methods for Electrical Conductivity and Resis-
1.3.1 Long-term performance on feed waters containing
tivity of Water
foulants or sparingly soluble solutes, or both,
D1129 Terminology Relating to Water
1.3.2 Performance on feeds of brackish water, sea water, or
D1193 Specification for Reagent Water
other high-salinity feeds,
D1293 Test Methods for pH of Water
1.3.3 Performance on synthetic industrial feed solutions,
D2777 Practice for Determination of Precision and Bias of
pharmaceuticals, or process solutions of foods and beverages,
Applicable Test Methods of Committee D19 on Water
or,
D4189 Test Method for Silt Density Index (SDI) of Water
1.3.4 Performance on feed waters less than 50 µS⁄cm,
particularly performance relating to organic solutes, colloidal 3. Terminology
or particulate matter, or biological or microbial matter.
3.1 Definitions—For definitions of other terms used in this
test method, refer to Terminology D1129.
1.4 This test method, subject to the limitations previously
described, can be applied as either an aid to predict expected
3.2 Definitions of Terms Specific to This Standard:
deionization performance for a given feed water quality, or as
3.2.1 cell, n—an independently fed ion-depleting chamber
a test method to determine whether performance of a given
formed by two adjacent ion-exchange membranes, or by a
device has changed over some period of time. It is ultimately,
membrane and an adjacent electrode.
however, the user’s responsibility to ensure the validity of this
3.2.2 continuous electrodeionization (CEDI) device, n—a
test method for their specific applications.
device that removes ionized and ionizable species from liquids
using electrically active media and using an electrical potential
to influence ion transport, where the ionic transport properties
This test method is under the jurisdiction of ASTM Committee D19 on Water
and is the direct responsibilities of Subcommittee D19.08 on Membranes and Ion
Exchange Materials. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2022. Published November 2022. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approvedin2000.Lastpreviouseditionapprovedin2011asD6529–11,whichwas Standards volume information, refer to the standard’s Document Summary page on
withdrawn in July 2020 and reinstated in October 2022. DOI: 10.1520/D6529-22. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6529 − 22
of the active media are a primary sizing parameter. The CEDI unpressurized, ported to be capable of occasional cleanings or
devices typically comprise semipermeable ion-exchange mem- sanitizations, and incorporates needed safety features such as
branes and permanently charged ion-exchange media. Ex-
temperature and overflow protection. The tank also incorpo-
amples include continuous deionization, electrodiaresis, and rates a drain valve. During operation of the apparatus, the drain
packed-bed or filled-cell electrodialysis.
valve may be used in combination with a valve controlling the
rate of feed water to the apparatus to aid in control of solute
3.2.3 current effıciency, n—the ratio, expressed in percent,
concentrations, water level, and temperature within the tank.
of the net transfer of ionized and ionizable solutes per unit cell
The tank supplies water to a recirculation pump designed to
within a CEDI device, expressed in chemical equivalents
feed water to the CEDI device at a flow rate and pressure
transferred per unit time, to the number of coulombs trans-
consistent with the ratings of the CEDI device.Arecirculation
ferred from an external dc power source to each electrode pair,
line with a shut off valve from the pump discharge to the tank
expressed in faradays per unit time. Calculation of current
may be incorporated as required for proper pump operation.
efficiency is described in 9.2.
6.1.3 The concentration and pH of the feed water to the
4. Summary of Test Method
CEDI device is controlled by metering pumps that meter a
4.1 This test method is used to determine performance
controlled flow of concentrated aqueous sodium chloride, and
capabilities of CEDI devices with regard to extent of ion
either sodium hydroxide or hydrochloric acid as needed into
removal, pressure/flow relationships and electrical power con-
the feed water to maintain the desired feed water solute
sumption at standard or nominal operating conditions, electri-
concentration and pH.
cal current characteristics, and the relative ability of the device
6.1.3.1 The concentrated reagents may be metered into the
to remove ionized species when fed pretreated tap water. On
discharge line of the pump or alternately may be metered into
this type of feed there is little water splitting or resin
the tank. In either case, mixing means are required to ensure
regeneration, thus only ionized species are removed. This test
that the feed water concentrations do not fluctuate. Metering
method is applicable to both new and used devices.
pump assemblies and controllers should be designed with
4.2 Pressurelossdataisobtained.Thisinformationprovides
proper safety interlocks and controls configured so as to be
information relating to possible particulate plugging, fouling,
“fail safe.” Suitable instrumentation must be provided to
or internal damage of the device. Deionization performance,
monitor solute concentration (by means of electrical conduc-
concentrating stream pH, and electrical current transfer is
tivity or resistivity, see Test Methods D1125), pH (Test
monitored as a function of applied voltage. The initial ohmic
Methods D1293), and temperature of the feed water to the
(electrical) resistance, rate of change of ohmic resistance, and
CEDI device. Instrumentation may be in-line or alternately,
maximal ohmic resistance is determined. Also the electrical
appropriate sample taps may be incorporated to allow for
current efficiency as a function of deionization performance
determination off-line.
and voltage is determined. This information in combination
6.1.4 Feed water provided to the CEDI device should be
with concentrating stream pH as a function of applied voltage
plumbed as specified by the supplier, with appropriate flow and
provides basic design and performance information.
pressure controls, internal recirculations, drains, interlocks,
safety controls, and other features as required. Pressure at the
5. Significance and Use
inlet and outlet and flow rates of each of the streams of interest
5.1 The CEDI devices can be used to produce deionized
must be monitored (for example, deionized water stream,
water from feeds of pretreated water. This test method permits
concentrate stream, and electrode feed stream).
the relatively rapid measurement of key performance capabili-
6.1.5 The CEDI device should be powered as specified by
ties of CEDI devices using standard sets of conditions. The
the supplier, with equipment and wiring to provide appropriate
data obtained can be analyzed to provide information on
supply dc voltage and amperage, controls, interlocks,
whether changes may have occurred in operating characteris-
grounding, and safety features. Supply voltage and supply
tics of the device independently of any variability in feed water
amperage to the CEDI device should be monitored at positions
characteristics or operating conditions. Under specific
within the device or device assembly as specified by the
circumstances, this test method may also provide sufficient
supplier.
information for plant design.
6.1.6 Streams leaving the CEDI device may be returned to
6. Apparatus
the tank by means of return lines. Alternately, one or more of
the streams may be sent either completely or partially to drain
6.1 Description:
by means of appropriate valving if such operation provides
6.1.1 The test apparatus is schematically represented in Fig.
easier control of desired feed water conditions. The outlet
1. Feed water to the apparatus may be passed through a heat
deionization stream is monitored for electrical conductivity or
exchanger or other accessories, or both, to modify or control
resistivity and optionally pH, and the outlet concentrating
feed water temperature, or both, as desired. Alternatively, data
obtained from the operation of the apparatus may be normal- stream is monitored for pH and optionally electrical conduc-
ized for temperature if normalization factors are known. tivity or resistivity. For CEDI devices with internal recircula-
6.1.2 Feed water to the apparatus enters a holding tank tion and “feed and bleed” features, solute concentrations must
(open or vented) of volume sufficient to maintain good control be measured at locations that are indicative of conditions
of water level and solute concentrations. The tank is within the CEDI module prior to mixing of recirculation flows.
D6529 − 22
FIG. 1 Process Flow Schematic Test Method for Operating Performance of Continuous Electrodeionization Systems on Feeds from 50 µS⁄cm to 1000 µS⁄cm
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