1、Designation: D6908 06 (Reapproved 2017)Standard Practice forIntegrity Testing of Water Filtration Membrane Systems1This standard is issued under the fixed designation D6908; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、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 determination of the integrity ofwater filtration membrane elements and systems using airb
3、ased tests (pressure decay and vacuum hold), soluble dye,continuous monitoring particulate light scatter techniques, andTOC monitoring tests for the purpose of rejecting particles andmicrobes. The tests are applicable to systems with membranesthat have a nominal pore size less than about 1 m. The TO
4、C,and Dye, tests are generally applicable to NF and RO classmembranes only.1.2 This practice does not purport to cover all availablemethods of integrity testing.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standa
5、rd does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This inter
6、national standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) C
7、ommittee.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3864 Guide for On-Line Monitoring Systems for Water
8、AnalysisD3923 Practices for Detecting Leaks in Reverse Osmosisand Nanofiltration DevicesD4839 Test Method for Total Carbon and Organic Carbon inWater by Ultraviolet, or Persulfate Oxidation, or Both, andInfrared DetectionD5173 Guide for On-Line Monitoring of Total OrganicCarbon in Water by Oxidation
9、 and Detection of ResultingCarbon DioxideD5904 Test Method for Total Carbon, Inorganic Carbon, andOrganic Carbon in Water by Ultraviolet, PersulfateOxidation, and Membrane Conductivity DetectionD5997 Test Method for On-Line Monitoring of TotalCarbon, Inorganic Carbon in Water by Ultraviolet, Persul-
10、fate Oxidation, and Membrane Conductivity DetectionD6161 Terminology Used for Microfiltration, Ultrafiltration,Nanofiltration and Reverse Osmosis Membrane ProcessesD6698 Test Method for On-Line Measurement of TurbidityBelow 5 NTU in WaterE20 Practice for Particle Size Analysis of Particulate Sub-sta
11、nces in the Range of 0.2 to 75 Micrometres by OpticalMicroscopy (Withdrawn 1994)3E128 Test Method for Maximum Pore Diameter and Perme-ability of Rigid Porous Filters for Laboratory UseF658 Practice for Calibration of a Liquid-Borne ParticleCounter Using an Optical System Based Upon LightExtinction (
12、Withdrawn 2007)33. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard, refer toTerminologies D6161 and D1129.3.1.2 For description of terms relating to cross flow mem-brane systems, refer to Terminology D6161.3.1.3 For definition of terms relating to dissolved carbonand
13、carbon analyzers, refer to Guide D5173 and Test MethodsD5904 and D5997.3.2 Definitions of Terms Specific to This Standard:3.2.1 bubble point, nwhen the pores of a membrane arefilled with liquid and air pressure is applied to one side of the1This practice is under the jurisdiction of ASTM Committee D
14、19 on Water andis the direct responsibility of Subcommittee D19.08 on Membranes and IonExchange Materials.Current edition approved Dec. 1, 2017. Published December 2017. Originallyapproved in 2003. Last previous edition approved in 2010 as D6908 06 (2010).DOI: 10.1520/D6908-06R17.2For referenced AST
15、M 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.3The last approved version of this historical standard is referenced onwww.astm.
16、org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of I
17、nternational Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1membrane, surface tension prevents the liquid in the poresfrom being blown out by air pressure below a minimumpressure known as the bubble point.3.2.2 equivalent dia
18、meter, nthe diameter of a pore ordefect calculated from its bubble point using Eq 1 (see 9.3).This is not necessarily the same as the physical dimensions ofthe defect(s).3.2.3 integrity, nmeasure of the degree to which a mem-brane system rejects particles of interest. Usually expressed asa log reduc
19、tion value (LRV).3.2.4 log reduction value (LRV), na measure of theparticle removal efficiency of the membrane system expressedas the log of the ratio of the particle concentration in theuntreated and treated fluid. For example, a 10-fold reduction inparticle concentration is an LRV of 1. The defini
20、tion of LRVwithin this practice is one of many definitions that are usedwithin the industry. The user of this practice should use care asnot to interchange this definition with other definitions thatpotentially exist. The U.S. EPA applies the LRV definition topathogens only.3.2.5 membrane system, nr
21、efers to the membrane hard-ware installation including the membrane, membranehousings, interconnecting plumbing, seals and valves. Themembrane can be any membrane with a pore size less thanabout 1 m.3.2.6 multiplexing, vthe sharing of a common set ofphysical, optical, and/or electrical components ac
22、ross multiplesystem sample points. Two approaches of multiplexing areconsidered in this practice: sensor multiplexing and liquidmultiplexing. Sensor multiplexing monitors a unique samplewith a dedicated sensor. Sensors are linked to a centralizedlocation, where data processing and the determinative
23、mea-surement is performed. Liquid multiplexing uses a commoninstrument to measure multiple process sample streams in asequential manor. Samples are fed to the common analyzer viaa system of a manifold, valves, and tubing.3.2.7 relative standard deviation (RSD), na generic con-tinuous monitoring para
24、meter used to quantify the fluctuationof the particulate light scatter baseline from a laser-basedincident light source. As an example, the RSD may becalculated as the standard deviation divided by the average fora defined set of measurements that are acquired over a shortperiod of time. The result
25、is multiplied by 100 to express thevalue as a percentage and is then reported as % RSD. Thesample monitoring frequency is typically in the range of 0.1 to60 seconds. The RSD parameter is specific for laser-basedparticulate light-scatter techniques which includes particlecounters and laser turbidimet
26、ers. The RSD is can be treated asan independent monitoring parameter. Other methods for RSDcalculations may also be used.3.2.8 UCL, na generic term to represent the aggregatequantity of material that causes an incident light beam to bescattered. The value can be correlated to either turbidity or tos
27、pecific particle count levels of a defined size.4. Significance and Use4.1 The integrity test methods described are used to deter-mine the integrity of membrane systems, and are applicable tosystems containing membrane module configurations of bothhollow fiber and flat sheet; such as, spiral-wound c
28、onfiguration.In all cases the practices apply to membranes in the RO, NF,and UF membrane classes. However, the TOC and Dye Testpractices do not apply to membranes in the MF range or theupper end of the UF pore size range (0.01 m and larger poresizes) due to insignificant or inconsistent removal of T
29、OCmaterial by these membranes.4.2 These methods may be used to identify relative changesin the integrity of a system, or used in conjunction with theequations described in 9.4, to provide a means of estimating theintegrity in terms of log reduction value. For criticalapplications, estimated log redu
30、ctions using these equationsshould be confirmed by experiment for the particular mem-brane and system configuration used.4.3 The ability of the methods to detect any given defect isaffected by the size of the system or portion of the systemtested. Selecting smaller portions of the system to test wil
31、lincrease the sensitivity of the test to defects. When determiningthe size that can be tested as a discrete unit, use the guidelinessupplied by the system manufacturer or the general guidelinesprovided in this practice.4.4 The applicability of the tests is largely independent ofsystem size when meas
32、ured in terms of the impact of defects onthe treated water quality (that is, the system LRV). This isbecause the bypass flow from any given defect is diluted inproportion to the systems total flowrate. For example, a10-module system with a single defect will produce the samewater quality as a 100-mo
33、dule system with ten of the same sizedefects.5. Reagents and Materials5.1 ReagentsAs specified for the TOC analyzer in ques-tion. Guide D5173 lists requirements for a variety of instru-ments.5.2 Soluble Dye SolutionUse FD that is, the conservative situation of cos = 1. In practicemost membranes used
34、 in water treatment have a contact anglegreater than zero, which is represented by the shaded regionunder the solid line in Fig. 3. If the contact angle is known orcan be determined, Eq 1 may be used. However, if the contactangle is not known, a conservative estimate of the test pressurerequired can
35、 be made by applying Eq 2.9.3.3 The test pressure is usually selected to ensure that theminimum defect diameter picked up by the test is smaller thancontaminates or particles of interest. For example, Eq 2indicates that a test pressure of 100 kPa would include alldefects larger than or equal to 3 m.
36、Alower pressure could beused for less hydrophilic membranes. For example, if thecontact angle is 60 degrees (typical for polypropylene,polysulfone, or PVdF) Eq 1 indicates that defects of 3 mwould be included at a test pressure of 50 kPa. An even lowertest pressure may be used for larger defects, su
37、ch as forexample detection of broken fibers in a hollow fiber system.9.3.4 In practice the applied test pressure is rarely more than300 kPa, which is usually sufficient to include defects smallerthan most pathogens of interest. At this pressure limit the testis not suitable for direct validation of
38、virus rejection as theseparticles are very small (typically less than 0.01 m) with acorresponding test pressure of several thousand kilopascals.9.4 Interpreting PDR and VDR Results as Log ReductionValuesBoth the PDR and the VDR are measurements of theairflow from one side of the membrane to the othe
39、r under aknown set of test conditions (temperature and pressure). Thisinformation can be used to estimate the flow of liquid throughthe same defects during filtration conditions. This provides anestimate of the membrane bypass flow and thereby an estimateof the log removal of particles for the syste
40、m. One approach isbased on the Hagen-Poiseuille law, which assumes laminarflow through cylindrical defects. Whilst this method provides auseful estimate, its applicability is limited to small fibers ( 300 to 400 m lumen diameter) which can leadto error in the calculated LRV.As with all methods to co
41、rrelateintegrity test results to LRV the relationship should be verifiedby field tests for the particular membrane and configurationused.X2. GUIDANCE TO OBTAINING RELIABLE AND QUALITY MEASUREMENT DATA FROM CONTINUOUSMONITORING SYSTEMSX2.1 Throughout Practice D, there contains several piecesof key sa
42、mpling information related to instrument setup,sampling and data handling that aid in achieving optimumreliability and sensitivity for these technologies.Asummary ofthis information is provided below:X2.1.1 Common turbimeters such as those that comply withU.S. EPAMethod 180.1 are not suggested for u
43、se due to havinglower sensitivity. Laser turbidimeters with a greater sensitivityare suggested (see 22.3).X2.1.2 Insure instrumentation is installed at appropriatesample points that insure a homogeneous and representativesample. Sample points that insure filtrate or permeate waterchanges direction (
44、such as following a 90-degree elbow) aresuggested (see 23.3.1).X2.1.3 Instrument bodies (sensor bodies) must be condi-tioned prior to the establishment of any baseline that is used foran upper control limit (UCL) or alarm condition. A stablecontinuous monitoring baseline is represented by a levelmea
45、surement values that are void of random and unpredictedspikes (see 25.1).X2.1.4 Continuous monitoring methods can be applied toeither positive or negative filtration, but both types requiredifferent sampling to minimize bubble interference. The fol-lowing information can be used as guidance for spec
46、ific typesof membranes:X2.1.4.1 For UF, NF, and RO systems with no air backwashrequire the least amount of sampling conditioning becausebubble generation during the cleaning processes in minimal.Typically, reverse-flow cleanings do not cause spikes in themeasured values. Standard sampling protocols
47、that are pro-vided by the instrument manufacturers are adequate (see 23.3).X2.1.4.2 MF and UF systems that are outside infiltrationprocesses often use air scour at the within filtration cycle. Forthese systems, bubble generation and subsequent bubble inter-ference can occur. For these systems bubble
48、 interferences areminimized through the use of: (1) sample chambers that can bepressurized to prevent further outgassing (see 25.1); (2) addi-tional bubble traps such as those that contain a larger volumemay be added to dampen bubble interference (see 25.1); (3) theintegration of a signal from the r
49、ack that indicates the stoppageof forward filtration flow can be fed to either the plant(SCADA) system or data logging program. Under this condi-tion data is either ignored or not logged (see 25.2); and (4) atime lag should be incorporated into the data logging programto ignore data for the first 2 to 6 minutes (user changeable) afterthe completion of an air-scour cleaning procedure. This is to allfor air to vacate sample lines prior to resuming the logging ofmeasurement data (see 25.2). Many instruments contain mea-surement algorithms that aid in the reduction or r
