1、Designation: D6249 06 (Reapproved 2011)Standard Guide forAlkaline Stabilization of Wastewater Treatment PlantResiduals1This standard is issued under the fixed designation D6249; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear 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. Scope*1.1 This document provides guidance for use of reactivealkaline materials (quicklime, hydrated lime, high lime fly
3、 ash,or other byproducts) for treating wastewater solids (biosolids)to reduce pathogen levels and achieve compliance with regu-latory requirements. Federal (40 CFR, Part 503) regulations foruse or disposal of biosolids became effective on March 22,1993; refer to USEPA regulations and guidance docume
4、nts forinformation on other treatment processes or for specific re-quirements for use or disposal of biosolids.1.2 Additional requirements may be imposed by individualstates, and these are available through state regulatory agenciesthat issue permits for treatment and use or disposal, or both, ofbio
5、solids.1.3 This guide does not purport to address all of the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced D
6、ocuments2.1 ASTM Standards:2C25 Test Methods for Chemical Analysis of Limestone,Quicklime, and Hydrated LimeC110 Test Methods for Physical Testing of Quicklime,Hydrated Lime, and Limestone2.2 USEPA Publication:Title 40, Code of Federal Regulations (CFR), Part 503,Standards for the Use or Disposal of
7、 Sewage Sludge; FinalRules, 58 FR 9248-940433. Terminology3.1 Acronyms:acronymsthese are defined by operatingparameters (for example, time, temperature) whose valuesmust be met in order for biosolids to be used in various waysas a nutrient source/soil conditioner. Ref. 40 CFR Part 257.3.1.1 PFRPProc
8、esses to Further Reduce Pathogens(equivalent to 503 Class A).3.1.2 PSRPProcesses to Significantly Reduce Pathogens(equivalent to 503 Class B).4. Significance and Use4.1 Operators of power and other plants producing alkalineby-products and wastewater treatment plant operators needingto treat and mana
9、ge wastewater solids will find this guidehelpful in dealing with their materials.4.2 This guide provides the tests, procedures, and param-eters that should be considered to significantly reduce patho-gens in wastewater treatment plant solids by the addition ofmanufactured or by-product alkaline mate
10、rials (1).45. Alkaline Materials Characteristics5.1 Chemical Composition:Alkaline materials may be tested for Available Lime Index(ALI) in accordance with the optional chemical test of Table 1.Other chemical components, if required, may be determined inaccordance with the appropriate procedure when
11、requested bythe purchaser.5.2 Reactivity:5.2.1 Alkaline materials should be tested for pH and heat ofhydration (heat rise or slaking rate) in accordance with therecommended tests of Table 2.5.3 Physical Characteristics:5.3.1 Alkaline materials should be tested to determine theparticle size in accord
12、ance with the recommended physicaltests of Table 3.6. Process Performance6.1 PFRP (Class A) Alkaline Treatment of Biosolids:1This guide is under the jurisdiction of ASTM Committee C07 on Lime and isthe direct responsibility of Subcommittee C07.02 on Specifications and Guidelines.Current edition appr
13、oved June 1, 2011. Published July 2011. Originally approvedin 1998. Last previous edition approved in 2006 as D6249 06. DOI: 10.1520/D6249-06R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards
14、volume information, refer to the standards Document Summary page onthe ASTM website.3Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.4The boldface numbers in parentheses refer to the lis
15、t of references at the end ofthis guide.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.1 MixingThorough mixing of the biosolids and stabi-lization reagent must be
16、 provided to ensure uniform pHdistribution and pathogen reduction throughout the biosolidsmass (2). Effective mixing depends upon achieving the appro-priate ratio of alkaline material to biosolids cake uniformlydistributed throughout the treated biosolids.6.1.1.1 Biosolids with a high moisture conte
17、nt will requireless mixing energy than high-solids biosolids cake.6.1.1.2 Biosolids characteristics will determine the propertype of equipment or system required for adequate mixing.Incomplete mixing can cause odor release during productstorage or application and may lead to failure to meet regula-t
18、ory requirements for pathogen and vector control.6.1.2 Particle Size:6.1.2.1 Given an adequate moisture supply using alkalineagents (for example, CaO) with smaller particle sizes willfacilitate rapid and efficient mixing of agents with biosolidsand increase reaction rates and pH, resulting in higher
19、 tem-peratures and greater pathogen reduction.6.1.2.2 Since dusts are more easily generated from finelydivided particles, precautions should be taken to preventexposure to eyes and mucous membranes, which may result inirritation.6.1.2.3 Reactivity and particle size also affect the rate ofdust and mi
20、st emissions from reactors or mixing devices, orboth. Particulate release may require scrubbing, water spray, orother emission controls on reactors or mixing devices foraesthetic reasons or to meet regulatory requirements.6.1.2.4 Very small particle size may also lead to “airslaking” or recarbonatio
21、n of active lime particles if the materialis exposed to high humidity. Air slaked/recarbonated materialswill not achieve the pH necessary to meet regulatory require-ments.6.1.3 Reactivity (Heat and pH Elevation):6.1.3.1 Reactivity is dependent upon the interaction be-tween the alkaline reagent and t
22、he material to be treated.Reactions occur as the alkaline material contacts the biosolids.The finer the alkaline product, the greater the potential for amore rapid pH/temperature elevation.6.1.3.2 Reagent reactivity affects mixing time and dosagerate and must be considered in process design.6.1.4 Mo
23、isture Content:6.1.4.1 Adequate moisture must be present to react with thefree CaO (as measured by Available Lime Index, ALI, as perTest Methods C25) to generate heat and elevate pH. Generally,dry biosolids cakes (18 to 30 %) require a more intimate mix toensure proper penetration and reaction than
24、is required by wetbiosolids (less than 18 %).6.1.4.2 The calcium oxide in the reagent must react with themoisture in biosolids (hydration) producing calcium hydroxideand heat. The moisture content in the biosolids mass must besufficient to allow the hydration reaction to occur between theselected re
25、agent (CaO concentration and fineness) and biosol-ids mass.6.1.4.3 Biosolids cakes with a high moisture content willtend to react faster than biosolids with a low moisture content.6.1.5 Biosolids Type:6.1.5.1 Case-by-case alkaline material demand should bedetermined for each biosolids type through p
26、ilot testing usingthe actual biosolids cake and proposed reagents for eachproject. Develop process guidelines for alkaline additions bybiosolids type and alkaline additive characteristics.6.1.5.2 Biosolids with a high moisture content may requirea higher dose ratio than drier dewatered biosolids cak
27、e whendosage ratios are expressed on a dry weight basis.6.1.6 Reaction Time and Curing Time:6.1.6.1 Heat will be generated as hydration of calcium oxideoccurs. The reaction time will vary depending on reagentcomposition moisture content of the biosolids mass, and mixerefficiency.6.1.6.2 Reaction tim
28、es to effect pathogen reduction areestablished by applicable federal and state regulations.Reaction/cure times depend upon a number of variables andshould be pilot-tested using the actual biosolids cake, alkalineadmixture, mix unit, cure vessel, and testing protocol andacceptance criteria to assure
29、compliance with regulatory stan-dards.6.1.6.3 For alkaline treatment processes, one of the threeperformance criteria is required:(1) The time-temperature relation established in 40 CFR503.32 (a) (3) (Alternative 1). Selected time-temperaturevalues are as follows:Biosolids Temp, C 50 55 60 65 70 75 8
30、0Moisture 7 % Time, hours 316 63 13 2.5 0.5 0.10 0.020Moisture 12 for 2 h or more.BModify Test Method C110 to proportion alkaline reagent in lieu of quicklime.Alkaline material and water ratio may need to be modified to obtain measurableresults. Any modification of Test Method C110 must be clearly s
31、tated on theanalysis report.CTo be specified only as required by purchaser.TABLE 3 Recommended Physical TestASTM Test Method Component SpecificationC110 Amount retained on 600 mA(No. 30 mesh), %C110 Amount retained on 75 m(No. 200 mesh), %AATo be specified only as required by purchaser.D6249 06 (201
32、1)26.1.6.4 Ammonia or other odors released may require waterspray, scrubbing, gas capture, or control of emission.6.1.7 Reaction/Cure Vessels or Containers:6.1.7.1 Consideration should be given to minimize heatlosses through materials management, configuration, and ma-terials of construction for pro
33、cesses that require extendedcuring times.6.1.7.2 Proper temperatures can be maintained without aninsulated vessel by adding adequate alkaline reagent to com-pensate for heat loss. However, some situations may benefitfrom an insulated vessel to efficiently retain the heat to meetPFRP temperature requ
34、irements.6.1.7.3 For processes using a windrow, at a minimum, themixture should be at least 18 inches thick at all locations in thepile to ensure heat retention throughout the entire mass for theapplicable curing time. Thin areas at the pile extremities shouldbe avoided as they will not retain adequ
35、ate heat and can lead topotential regrowth and recontamination of the entire mass.6.1.8 Process Testing Requirements:6.1.8.1 Process testing requirements vary with the specificalkaline process selected.6.1.8.2 Temperature and pH measurements for the requisitetime periods should be recorded to comply
36、 with pathogenreduction (and vector attraction reduction). Daily testing mayinclude monitoring and documenting the elevated temperatureand pH for a predetermined period of time (see 6.2.6 fordetails). Some methods also require documentation of reducedmoisture content and mixing.6.1.8.3 Procedures to
37、 monitor or collect samples for analy-sis are developed for each project based upon site-specificconditions considering the process selected, equipment uti-lized, volumes of materials to be processed, local state andfederal regulatory requirements, and local conditions (3).6.1.9 Process Testing Sche
38、dule:6.1.9.1 Testing must be conducted in accordance with fed-eral, state, and local regulations. Product testing, to meetend-use requirements, will be site-specific. Under 40 CFR Part503 regulations, pathogen (salmonella, virus, protozoan, andhelminth egg) or indicator organism testing and pollutan
39、tconcentration (metals) testing requirements are:Amount of Biosolids(dry metric tons/365 days) Frequency 0 and 12 for twohours.6.2.7.1 When testing a liquid/solid mixture with a systemdesigned for liquids (pH probe), care must be taken to keepflow of sample moving across the pH probe surface foraccu
40、racy. Clean the electrode frequently, paying particularattention to the reference electrode junction. Bits of adherentbiosolids or alkaline agent can strongly alter the measured pH,resulting in erroneous values not representative of the entiremass of material. pH measurements should be made at 25C,
41、orcorrected for sample temperature differences as shown in Table4, which demonstrates the temperature/pH relationship as themeasured pH approaches the regulatory limit.NOTE 1At high pH (above 11), temperature has a significant effect onpH readings. Therefore, at high pH levels, the reading must be c
42、orrectedto 25C, standard temperature. Table 4 and following examples may beuseful for a better understanding.NOTE 2pH meters often have temperature correction controls. Thesecontrols correct for probe temperature and conductivity only. Changes inthe concentration of the test sample due to solubility
43、 that changes withtemperature are not compensated by these controls. For example, at 30C:Correction Factor (CF) = 0.03 pH units 3 (Tmeas 25C)CF = 0.03 3 (30 25); CF = 0.03 3 5CF = + 0.15Actual pH = Measured pH 6 the Correction FactorActual pH = 12.304 + 0.15 = 12.4546.2.7.2 pHCalibrate routinely wit
44、h laboratory-grade stan-dards developed for high pH monitoring.6.2.8 On-Site Storage:6.2.8.1 PSRP (Class B) biosolids have regulatory restric-tions preventing application of material to a site duringinclement weather, standing water, ice- or snow-covered fields.6.2.8.2 On-site storage should be cons
45、idered to hold biosol-ids, unless backup options are available when application sitescannot be used. Storage design must address regulatory con-cerns for runoff or leachate and local site-specific concerns forodor. Storage capacity should be consider worst-case weatherconditions.6.2.8.3 Microbial re
46、contamination and regrowth is possibleat pH 10, with concomitant odor potential.7. End Use Criteria7.1 Matrix of Product Factors:7.1.1 Table 5 addresses various factors that influence spe-cific product criteria for alkaline-treated biosolids. The relativeimportance of these criteria will depend on t
47、he type of productand its intended use; for example, for agricultural limingmaterial, CaCO3equivalency and friability for handling will beimportant, along with metal levels, which must meet Table 3 ofEPAs 503 Rule for a product to be sold or distributed.EPA 40 CFR Part 503.13 (13 (Table 3)Metal Conc
48、entration LimitsMetalPollutantConcentrations (mg/kg)Arsenic 41Cadmium 39Copper 1,500Lead 300Mercury 17Molybdenum 75ANickel 420Selenium 100Zinc 2,800AThis is the ceiling concentration for Molybdenum. EPA is still developing apollutant concentration value.8. Federal Regulations8.1 Introduction:8.1.1 P
49、athogen reductionAlkaline materials reducepathogens in municipal wastewater solids by creating a seriesof stresses on the microbial population in the solids. Theaddition of an alkaline material raises the pH of the mixture tolevels that are toxic to some microbes, resulting in theirreduction or elimination (5). The exothermic reaction ofquicklime with water also releases heat (often intense) and theresultant temperature rise helps inactivate pathogens. Hydra-tion of alkaline oxide materials helps dry the biosolids, furtherstressing the microorganisms.8.2 Class A
