1、Designation: D 6249 06Standard Guide forAlkaline Stabilization of Wastewater Treatment PlantResiduals1This standard is issued under the fixed designation D 6249; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 ash,or other b
3、yproducts) 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 documents forinformat
4、ion 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, ofbiosolids.1.3 This
5、 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 Documents2.1 AST
6、M 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 Sewage Sludge;
7、 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 PFRPProcesses to Furthe
8、r 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 manage wastewater s
9、olids 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 materials (1).45. A
10、lkaline 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 requested bythe
11、 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 accordance with the r
12、ecommended physicaltests of Table 3.6. Process Performance6.1 PFRP (Class A) Alkaline Treatment of Biosolids:6.1.1 MixingThorough mixing of the biosolids and stabi-lization reagent must be provided to ensure uniform pHdistribution and pathogen reduction throughout the biosolids1This guide is under t
13、he jurisdiction of ASTM Committee C07 on Lime and isthe direct responsibility of Subcommittee C07.03 on Industrial Uses.Current edition approved June 1, 2006. Published June 2006. Originallyapproved in 1998. Last previous edition approved in 2004 as D 6249 98(2004).2For referenced ASTM standards, vi
14、sit 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.3Available from the Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC
15、 20402.4The boldface numbers in parentheses refer to the list 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.mass (2). Effective
16、 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 content will requireless mixing energy than high-solids biosolids cake.6.1.1.2 Biosolids characteristics will dete
17、rmine 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-tory requirements for pathogen and vector control.6.1.2 Particle Size:6.1.2.1 Given an adequate moisture suppl
18、y 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 tem-peratures and greater pathogen reduction.6.1.2.2 Since dusts are more easily generated from finelydivide
19、d 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 mist emissions from reactors or mixing devices, orboth. Particulate release may require scrubbing, water spray,
20、 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 recarbonation of active lime particles if the materialis exposed to high humidity. Air slaked/recarbonated materialswill
21、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 the material to be treated.Reactions occur as the alkaline material contacts the biosolids.The finer the alkal
22、ine 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 Moisture Content:6.1.4.1 Adequate moisture must be present to react with thefree CaO (as measured by Available
23、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 is required by wetbiosolids (less than 18 %).6.1.4.2 The calcium oxide in the reagent must react with themois
24、ture 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 reagent (CaO concentration and fineness) and biosol-ids mass.6.1.4.3 Biosolids cakes with a high moisture conte
25、nt 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 pilot testing usingthe actual biosolids cake and proposed reagents for eachproject. Develop process guidelines
26、 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 cake whendosage ratios are expressed on a dry weight basis.6.1.6 Reaction Time and Curing Time:6.1.6.1 Heat will
27、 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 times to effect pathogen reduction areestablished by applicable federal and state regulations.Reaction/cure time
28、s 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 compliance with regulatory stan-dards.6.1.6.3 For alkaline treatment processes, one of the threeperformance c
29、riteria 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 80Moisture 7 % Time, hours 316 63 13 2.5 0.5 0.10 0.020Moisture 12 for 2 h or more.BModify Test Method C110to
30、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 stated on theanalysis report.CTo be specified only as required by purchaser.TABLE 3 Recommended Physical TestAS
31、TM 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.D62490626.1.7.1 Consideration should be given to minimize heatlosses through materials management, configuration, and ma-te
32、rials of construction for processes 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
33、 to meetPFRP temperature requirements.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
34、as they will not retain adequate 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
35、 should be recorded to comply 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
36、 mixing.6.1.8.3 Procedures to 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 (
37、3).6.1.9 Process Testing Schedule: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
38、organism testing and pollutantconcentration (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
39、 the pH probe surface foraccuracy. 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 measure
40、ments should be made at 25C, 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
41、levels, the reading must be correctedto 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
42、test sample due to solubility 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.
43、7.2 pHCalibrate routinely with 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 O
44、n-site storage should be considered 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 weatherco
45、nditions.6.2.8.3 Microbial recontamination 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 th
46、ese criteria will depend on the 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 5
47、03.13 (13 (Table 3)Metal Concentration 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 Regula
48、tions8.1 Introduction:8.1.1 Pathogen 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, result
49、ing 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 Pathogen Reduction:8.2.1 All 40 CFR Part 503 Class A alternatives must meetthe following criteria:8.2.1.1 Either the density of fecal coliform in the biosolidsmust be less than 1000 most probable numbers (MPN) pergram total solids (dry-weight basis), or the density of Salmo
