1、Designation: D6586 03 (Reapproved 2014)Standard Practice forthe Prediction of Contaminant Adsorption On GAC InAqueous Systems Using Rapid Small-Scale Column Tests1This standard is issued under the fixed designation D6586; the number immediately following the designation indicates the year oforiginal
2、 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 a test method for the evaluation ofgranular ac
3、tivated carbon (GAC) for the adsorption of solublepollutants from water. This practice can be used to estimate theoperating capacities of virgin and reactivated granular acti-vated carbons. The results obtained from the small-scalecolumn testing can be used to predict the adsorption of targetcompoun
4、ds on GAC in a large column or full scale adsorberapplication.1.2 This practice can be applied to all types of waterincluding synthetically contaminated water (prepared by spik-ing high purity water with selected contaminants), potablewaters, industrial waste waters, sanitary wastes and effluentwate
5、rs.1.3 This practice is useful for the determination of break-through curves for specific contaminants in water, the deter-mination of the lengths of the adsorbates mass transfer zones(MTZ) and the prediction of GAC usage rates for larger scaleadsorbers.1.4 The following safety caveat applies to the
6、 proceduresection, Section 10, of this practice:This standard does notpurport to address all of the safety concerns, if any, associatedwith its use. It is the responsibility of the user of this standardto establish appropriate safety and health practices anddetermine the applicability of regulatory
7、limitations prior touse.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2652 Terminology Relating to Activated CarbonD2854 Test Method for Apparent Density of ActivatedCarbonD2867 Test Methods for Moisture in Activated CarbonD2862 T
8、est Method for Particle Size Distribution of Granu-lar Activated Carbon3. Terminology3.1 Definitions:3.1.1 For definitions of terms in this practice relating toactivated carbon, refer to Terminology D2652.3.1.2 For definitions of terms in this practice relating towater, refer to Terminology D1129.4.
9、 Summary of Practice4.1 This practice consists of a method for the rapid deter-mination of breakthrough curves and the prediction of GACusage rates for the removal of soluble contaminants fromwater. This is accomplished by passing the contaminated waterat a constant controlled rate down flow through
10、 a bed of aspecially sized granular activated carbon until predeterminedlevels of breakthrough have occurred.4.2 When the assumption is made that conditions of con-stant diffusivity exist within the GAC column, the break-through data obtained from the column test can be used toestimate the size and
11、operational conditions for a full-scalecarbon adsorber.5. Significance and Use5.1 Granular activated carbon (GAC) is commonly used toremove contaminants from water. However if not usedproperly, GAC can not only be expensive but can at times beineffective. The development of engineering data for the
12、designof full-scale adsorbers often requires time-consuming andexpensive pilot plant studies. This rapid standard practice hasbeen developed to predict adsorption in large-scale adsorbersbased upon results from small column testing. In contrast topilot plant studies, the small-scale column test pres
13、ented in thispractice does not allow for a running evaluation of factors thatmay affect GAC performance over time. Such factors may1This practice is under the jurisdiction of ASTM Committee D28 on ActivatedCarbon and is the direct responsibility of Subcommittee D28.02 on Liquid PhaseEvaluation.Curre
14、nt edition approved July 1, 2014. Published September 2014. Originallyapproved in 2000. Last previous edition approved in 2008 as D658603 (2008).DOI: 10.1520/D6586-03R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annu
15、al 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 States1include, for example, an increased removal of target com-pounds by bacterial
16、colonizing GAC3or long term fouling ofGAC caused by inorganic compounds or background organicmatter4. Nevertheless, this practice offers more relevant opera-tional data than isotherm testing without the principal draw-backs of pilot plant studies, namely time and expense; andunlike pilot plant studi
17、es, small scale studies can be performedin a laboratory using water sampled from a remote location.5.2 This practice known as the rapid small-scale column test(RSSCT) uses empty bed contact time (EBCT) and hydraulicloading to describe the adsorption process. Mean carbonparticle diameter is used to s
18、cale RSSCT results to predict theperformance of a full-scale adsorber.5.3 This practice can be used to compare the effectivenessof different activated carbons for the removal of contaminantsfrom a common water stream.6. Summary of Practice6.1 The development of the RSSCT is based on thedispersed-flo
19、w pore surface diffusion model (DFPSDM)(Crittenden, et al5) which takes into account many of themechanisms that are known to occur in fixed-bed adsorption.The following mechanisms, which cause the breakthroughcurves for an adsorber to spread out and create the masstransfer zone are included in the D
20、FPSDM: external mass-transfer resistance or film transfer, axial mixing due to disper-sion and the internal mass-transfer resistances of pore andsurface diffusion.6.2 To simulate full-scale performance, the amount ofspreading in the breakthrough curve relative to column depthmust be identical for th
21、e RSSCT and the full-scale column. Toachieve this, the relative contributions of the mechanisms thatcause most of the spreading are matched by maintainingsimilarity as the GAC process is scaled. Studies5have shownthat matching of the spreading of the breakthrough curve canbe achieved by equating the
22、 dimensionless groups in PFPSDM(Plug Flow Pore Surface Diffusion Model). Under the condi-tions that intraparticle diffusivities are assumed to be indepen-dent of the carbon particle radius, i.e. the condition of constantdiffusivity, the following equation describes the relationshipbetween the small
23、and large columns:EBCTscEBCTlc5SRscRlcD25tsctlc(1)where: EBCTscand EBCTlcare the empty-bed contact timesfor the small-column (RSSCT) and the large-column (full-scaleadsorber), respectively; Rscand Rlcare the radii of the carbonparticles used in the small and large columns, respectively; andtscand tl
24、care the elapsed times required to conduct the small-and large-column tests, respectively. The condition of constantdiffusivity also requires the Reynolds numbers for the RSSCTand the large-column be equal. This means the followingequation must also be satisfied:VscVlc5RlcRrc(2)where: Vscand Vlcare
25、the hydraulic loadings in the RSSCTand large columns, respectively. Based upon the aboveequations, the operating conditions for the RSSCT can beselected to precisely simulate the desired (specified) operatingconditions for a full-scale adsorber.NOTE 1There is an important issue relating to RSSCT des
26、ign usingEquation 26. Sometimes using leads to a design with a high head loss,which increases dramatically with operating time, as the GAC is crushedby a large pressure drop across the RSSCT. This may be avoided bylowering the superficial velocity as long as dispersion does not become thedominant tr
27、ansport mechanism and intraparticle mass transfer is limitingthe adsorption rate. The Peclet number based on diameter can be estimatedfrom the following equation7:Ped50.334 for 160#ReSc#40,000When the velocity is reduced below what is given in Equation A, axialdispersion, which is caused by molecula
28、r diffusion, can be more importantin the RSSCT than in the full scale process. Consequently, EquationAcanbe used to check whether dispersion becomes important as the velocity ofthe RSSCT is reduced in an effort to reduce the head loss. Typical Scvalues for SOCs is 2000; consequently, the Re for the
29、RSSCT must bekept greater than 0.1 and the Pe must be kept above 50 for the length ofthe mass transfer zone.NOTE 2Empty-bed contact time (EBCT) is defined as the bed volume(in liters) divided by the water flow rate in liters/minute. For example if afull scale adsorber holds 20 000 L of activated car
30、bon and the water flowrate is 2500 L/min, the EBCT would be equal to 20 000/2500 or 8.0 min.6.3 The assumption that conditions of constant diffusivityexist within the GAC column does not apply to all waters or alltarget compounds. For example this assumption does not applyfor the decolorization of w
31、ater and the adsorption of largemolecules, such as humic and fulvic acids. It is recommendedthat at least one RSSCTpilot-column comparison be conductedto aid in selecting the RSSCT design variables for a givenwater matrix (Crittenden, et al5). A detailed comparison be-tween the constant diffusivity
32、and proportional diffusivityapproaches and their respective domains of application isbeyond the scope of this practice.6.4 GAC bed volume and preparation methods are impor-tant design parameters for the RSSCT. The GAC bed volumeused will determine the required water pumping rate and affectthe amount
33、 of water needed to complete the test. The minimumcolumn diameter needed to avoid channeling should be 50particle diameters. For the 10-mm diameter column commonlyused in RSSCT systems, a 60 by 80 mesh carbon should beused. Proper GAC sampling (Practice E300) and preparation(grinding, classification
34、 and washing) are required for repro-ducible results.6.5 Based upon the water feed rate to the column, the timerequired to reach the desired breakpoint and the weight of3Owen, D.M., Chowdhury, Z.K., Summers, R.S., Hooper, S.M., and Solarik, G.,“Determination of Technology and Costs for GAC Treatment
35、 Using the ICRMethodology,”AWWAGAC column testing; granular activatedcarbon; RSSCTASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the v
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