1、Designation: D6908 06 (Reapproved 2010)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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 AST
6、M 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 Continual On-Line Monitoring Systemsfor Water AnalysisD3923 Practices for D
7、etecting Leaks in Reverse Osmosisand Nanofiltration DevicesD4839 Test Method for Total Carbon and Organic Carbonin Water by Ultraviolet, or Persulfate Oxidation, or Both,and Infrared DetectionD5173 Test Method for On-Line Monitoring of CarbonCompounds in Water by Chemical Oxidation, by UV LightOxida
8、tion, by Both, or by High Temperature CombustionFollowed by Gas Phase NDIR or by Electrolytic Conduc-tivityD5904 Test Method for Total Carbon, Inorganic Carbon,and Organic Carbon in Water by Ultraviolet, PersulfateOxidation, and Membrane Conductivity DetectionD5997 Test Method for On-Line Monitoring
9、 of Total Car-bon, Inorganic Carbon in Water by Ultraviolet, PersulfateOxidation, and Membrane Conductivity DetectionD6161 Terminology Used for Microfiltration, Ultrafiltra-tion, Nanofiltration and Reverse Osmosis Membrane Pro-cessesD6698 Test Method for On-Line Measurement of TurbidityBelow 5 NTU i
10、n WaterE20 Practice for Particle Size Analysis of Particulate Sub-stances in the Range of 0.2 to 75 m by Optical Micros-copy3E128 Test Method for Maximum Pore Diameter and Per-meability of Rigid Porous Filters for Laboratory UseF658 Practice for Calibration of a Liquid-Borne ParticleCounter Using an
11、 Optical System Based Upon LightExtinction33. Terminology3.1 DefinitionsFor definitions of terms used in this prac-tice, refer to Terminologies D6161 and D1129.3.1.1 For description of terms relating to cross flow mem-brane systems, refer to Terminology D6161.3.1.2 For definition of terms relating t
12、o dissolved carbonand carbon analyzers, refer to D5173, D5904 and D5997.3.1.3 bubble pointwhen the pores of a membrane arefilled with liquid and air pressure is applied to one side of themembrane, surface tension prevents the liquid in the poresfrom being blown out by air pressure below a minimumpre
13、ssure known as the bubble point.3.1.4 equivalent diameterthe diameter of a pore or defectcalculated from its bubble point using Eq 1 (see 9.3). This isnot necessarily the same as the physical dimensions of thedefect(s).1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the
14、 direct responsibility of Subcommittee D19.08 on Membranes and IonExchange Materials.Current edition approved May 1, 2010. Published May 2010. Originallyapproved in 2003. Last previous edition approved in 2006 as D6908 06. DOI:10.1520/D6908-06R10.2For referenced ASTM standards, visit the ASTM websit
15、e, 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.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org1Copyright ASTM Inte
16、rnational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.5 integritymeasure of the degree to which a mem-brane system rejects particles of interest. Usually expressed asa log reduction value (LRV).3.1.6 log reduction value (LRV)a measure of the particleremov
17、al efficiency of the membrane system expressed as thelog of the ratio of the particle concentration in the untreatedand treated fluid. For example, a 10-fold reduction in particleconcentration is an LRV of 1. The definition of LRV within thisStandard is one of many definitions that are used within t
18、heindustry. The user of this standard should use care as not tointerchange this definition with other definitions that poten-tially exist. The USEPA applies the LRV definition to patho-gens only.3.1.7 membrane systemrefers to the membrane hardwareinstallation including the membrane, membrane housing
19、s,interconnecting plumbing, seals and valves.The membrane canbe any membrane with a pore size less than about 1 m.3.1.8 multiplexingthe sharing of a common set of physi-cal, optical, and/or electrical components across multiplesystem sample points. Two approaches of multiplexing areconsidered in thi
20、s 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 mea-surement is performed. Liquid multiplexing uses a commoninstrument to measure mult
21、iple process sample streams in asequential manor. Samples are fed to the common analyzer viaa system of a manifold, valves and tubing.3.1.9 relative standard deviation (RSD)a generic continu-ous monitoring parameter used to quantify the fluctuation ofthe particulate light scatter baseline from a las
22、er-based incidentlight source. As an example, the RSD may be calculated as thestandard deviation divided by the average for a defined set ofmeasurements that are acquired over a short period of time.The result is multiplied by 100 to express the value as apercentage and is then reported as % RSD. Th
23、e samplemonitoring frequency is typically in the range of 0.1 to 60seconds. The RSD parameter is specific for laser-based par-ticulate light-scatter techniques which includes particlecounters and laser turbidimeters. The RSD is can be treated asan independent monitoring parameter. Other methods for
24、RSDcalculations may also be used.3.1.10 UCLa 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 tospecific particle count levels of a defined size.4. Significance and Use4.1 The integrity t
25、est 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 configuration.In all cases the practices apply to membranes in the RO, NF,and UF membrane c
26、lasses. 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 TOCmaterial by these membranes.4.2 These methods may be used to identify relative changesin
27、 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 critical applica-tions, estimated log reductions using these equations should beconfirmed by experiment for the particular membran
28、e andsystem 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 willincrease the sensitivity of the test to defects. When determiningthe size that can be tes
29、ted as a discrete unit, use the guidelinessupplied by the system manufacturer or the general guidelinesprovided in this standard.4.4 The applicability of the tests is largely independent ofsystem size when measured in terms of the impact of defects onthe treated water quality (that is, the system LR
30、V). 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-module system with ten of the same sizedefects.5. Reagents and Materials5.1 ReagentsAs speci
31、fied for the TOC analyzer in ques-tion. D5173 lists requirements for a variety of instruments.5.2 Soluble Dye SolutionUse FD that is, the conservative situation of cosu = 1. In practicemost membranes used in water treatment have a contact anglegreater than zero, which is represented by the shaded re
32、gionunder 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 be made by applying Eq 2.9.3.3 The test pressure is usually selected to ensure that theminimum
33、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.Alower pressure could beused for less hydrophilic membranes. For example, if thecontact angle is
34、 60 degrees (typical for polypropylene, polysul-fone, or PVdF) Eq 1 indicates that defects of 3 m would beincluded at a test pressure of 50 kPa. An even lower testpressure may be used for larger defects, such as for exampledetection of broken fibers in a hollow fiber system.9.3.4 In practice the app
35、lied 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 virus rejection as theseparticles are very small (typically less than 0.01 m) with acorrespond
36、ing 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 other under aknown set of test conditions (temperature and pressure). Thisinformation can be used
37、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 system. One approach isbased on the Hagen-Poiseuille law, which assumes laminarflow through cylindr
38、ical 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 correlateintegrity test results to LRV the relationship should be verifiedby field tests for the
39、 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 sampling information related to instrument setup,sampling and data handling that aid in achievin
40、g optimumreliability and sensitivity for these technologies.Asummary ofthis information is provided below:X2.1.1 Common turbimeters such as those that comply withUSEPA method 180.1 are not suggested for use due to havinglower sensitivity. Laser turbidimeters with a greater sensitivityare suggested (
41、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 (such as following a 90-degree elbow) aresuggested (see 23.3.1).X2.1.3 Instrument bodies (sensor
42、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 levelmeasurement values that are void of random and unpredictedspikes (see 25.1).X2.1.4 Continuous monit
43、oring 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 specific typesof membranes:X2.1.4.1 For UF, NF and RO systems with no air backwashrequire the least
44、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 that are pro-vided by the instrument manufacturers are adequate (see 23.3).X2.1.4.2 MF and UF sys
45、tems 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 interferences areminimized through the use of: (1) sample chambers that can bepressurized to pre
46、vent 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 rack that indicates the stoppageof forward filtration flow can be fed to either the plant(SCADA) s
47、ystem 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
48、 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 rejection ofbubble interference (see 24.1).D6908 06 (2010)19ASTM International takes no position respecting the validity of an
49、y patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM I
