ASTM D6249-06(2011)

Standard Guide for Alkaline Stabilization of Wastewater Treatment Plant Residuals

SIGNIFICANCE AND USE
Operators of power and other plants producing alkaline by-products and wastewater treatment plant operators needing to treat and manage wastewater solids will find this guide helpful in dealing with their materials.
This guide provides the tests, procedures, and parameters that should be considered to significantly reduce pathogens in wastewater treatment plant solids by the addition of manufactured or by-product alkaline materials (1).
SCOPE
1.1 This document provides guidance for use of reactive alkaline materials (quicklime, hydrated lime, high lime fly ash, or other byproducts) for treating wastewater solids (biosolids) to reduce pathogen levels and achieve compliance with regulatory requirements. Federal (40 CFR, Part 503) regulations for use or disposal of biosolids became effective on March 22, 1993; refer to USEPA regulations and guidance documents for information on other treatment processes or for specific requirements for use or disposal of biosolids.
1.2 Additional requirements may be imposed by individual states, and these are available through state regulatory agencies that issue permits for treatment and use or disposal, or both, of biosolids.
1.3 This guide does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-May-2011
• ICS: 13.060.30 - Sewage water
• Technical Committee: C07 - Lime and Limestone
• Drafting Committee: C07.02 - Specifications and Guidelines

Relations

• Replaces: ASTM D6249-06 - Standard Guide for Alkaline Stabilization of Wastewater Treatment Plant Residuals
• Effective Date: 01-Jun-2011
• Replaced By: ASTM D6249-19 - Standard Guide for Alkaline Stabilization of Wastewater Treatment Plant Residuals
• Effective Date: 01-May-2019
• Referred By: ASTM D5050-08(2023) - Standard Guide for Commercial Use of Lime Kiln Dusts and Portland Cement Kiln Dusts
• Effective Date: 01-Jun-2011
• Referred By: ASTM C911-19 - Standard Specification for Quicklime, Hydrated Lime, and Limestone for Selected Chemical and Industrial Uses
• Effective Date: 01-Jun-2011
• Referred By: ASTM C1529-19 - Standard Specification for Quicklime, Hydrated Lime, and Limestone for Environmental Uses
• Effective Date: 01-Jun-2011

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D6249 − 06 (Reapproved 2011)
Standard Guide for
Alkaline Stabilization of Wastewater Treatment Plant
Residuals
This standard is issued under the fixed designation D6249; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 3. Terminology
1.1 This document provides guidance for use of reactive 3.1 Acronyms—These are defined by operating parameters
alkalinematerials(quicklime,hydratedlime,highlimeflyash, (for example, time, temperature) whose values must be met in
or other byproducts) for treating wastewater solids (biosolids) order for biosolids to be used in various ways as a nutrient
to reduce pathogen levels and achieve compliance with regu- source/soil conditioner. Ref. 40 CFR Part 257.
latoryrequirements.Federal(40CFR,Part503)regulationsfor 3.1.1 PFRP—Processes to Further Reduce Pathogens
use or disposal of biosolids became effective on March 22, (equivalent to 503 Class A).
1993; refer to USEPAregulations and guidance documents for
3.1.2 PSRP—Processes to Significantly Reduce Pathogens
information on other treatment processes or for specific re-
(equivalent to 503 Class B).
quirements for use or disposal of biosolids.
4. Significance and Use
1.2 Additional requirements may be imposed by individual
states,andtheseareavailablethroughstateregulatoryagencies
4.1 Operators of power and other plants producing alkaline
that issue permits for treatment and use or disposal, or both, of
by-products and wastewater treatment plant operators needing
biosolids.
to treat and manage wastewater solids will find this guide
helpful in dealing with their materials.
1.3 This guide does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility
4.2 This guide provides the tests, procedures, and param-
of the user of this standard to establish appropriate safety and
eters that should be considered to significantly reduce patho-
health practices and determine the applicability of regulatory
gens in wastewater treatment plant solids by the addition of
limitations prior to use.
manufactured or by-product alkaline materials(1).
2. Referenced Documents
5. Alkaline Materials Characteristics
2.1 ASTM Standards:
5.1 Chemical Composition: Alkaline materials may be
C25Test Methods for Chemical Analysis of Limestone,
tested for Available Lime Index (ALI) in accordance with the
Quicklime, and Hydrated Lime
optional chemical test of Table 1. Other chemical components,
C110Test Methods for Physical Testing of Quicklime,
if required, may be determined in accordance with the appro-
Hydrated Lime, and Limestone
priate procedure when requested by the purchaser.
2.2 USEPA Publication:
5.2 Reactivity:
Title 40, Code of Federal Regulations (CFR), Part 503,
5.2.1 Alkaline materials should be tested for pH and heat of
StandardsfortheUseorDisposalofSewageSludge;Final
hydration (heat rise or slaking rate) in accordance with the
Rules, 58 FR 9248-9404
recommended tests of Table 2.
5.3 Physical Characteristics:
5.3.1 Alkaline materials should be tested to determine the
This guide is under the jurisdiction ofASTM Committee C07 on Lime and is
the direct responsibility of Subcommittee C07.02 on Specifications and Guidelines. particle size in accordance with the recommended physical
CurrenteditionapprovedJune1,2011.PublishedJuly2011.Originallyapproved
tests of Table 3.
in 1998. Last previous edition approved in 2006 as D6249–06. DOI: 10.1520/
D6249-06R11.
6. Process Performance
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6.1 PFRP (Class A) Alkaline Treatment of Biosolids:
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:// Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
www.access.gpo.gov. this guide.
*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
D6249 − 06 (2011)
TABLE 1 Optional Chemical Test
6.1.3.1 Reactivity is dependent upon the interaction be-
Test Method Component Specification tween the alkaline reagent and the material to be treated.
A
C25 Available Lime Index (ALI), %
Reactions occur as the alkaline material contacts the biosolids.
A
To be specified only as required by purchaser.
The finer the alkaline product, the greater the potential for a
more rapid pH/temperature elevation.
6.1.3.2 Reagent reactivity affects mixing time and dosage
TABLE 2 Recommended Reactivity Tests
rate and must be considered in process design.
ASTM Test Method Component Specification
A
C25 pH $ 12.0 6.1.4 Moisture Content:
B C
C110 Heat rise, C
6.1.4.1 Adequate moisture must be present to react with the
A
Based on 40 CFR Part 503 for pH >12 for 2 h or more.
free CaO (as measured by Available Lime Index, ALI, as per
B
Modify Test Method C110 to proportion alkaline reagent in lieu of quicklime.
TestMethodsC25)togenerateheatandelevatepH.Generally,
Alkaline material and water ratio may need to be modified to obtain measurable
results. Any modification of Test Method C110 must be clearly stated on the
drybiosolidscakes(18to30%)requireamoreintimatemixto
analysis report.
ensure proper penetration and reaction than is required by wet
C
To be specified only as required by purchaser.
biosolids (less than 18%).
6.1.4.2 Thecalciumoxideinthereagentmustreactwiththe
TABLE 3 Recommended Physical Test
moistureinbiosolids(hydration)producingcalciumhydroxide
ASTM Test Method Component Specification and heat. The moisture content in the biosolids mass must be
A
C110 Amount retained on 600 µm
sufficient to allow the hydration reaction to occur between the
(No. 30 mesh), %
selected reagent (CaO concentration and fineness) and biosol-
C110 Amount retained on 75 µm
A
(No. 200 mesh), %
ids mass.
A
To be specified only as required by purchaser.
6.1.4.3 Biosolids cakes with a high moisture content will
tend 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 be
6.1.1 Mixing—Thorough mixing of the biosolids and stabi-
determined for each biosolids type through pilot testing using
lization reagent must be provided to ensure uniform pH
the actual biosolids cake and proposed reagents for each
distribution and pathogen reduction throughout the biosolids
project. Develop process guidelines for alkaline additions by
mass (2). Effective mixing depends upon achieving the appro-
biosolids type and alkaline additive characteristics.
priate ratio of alkaline material to biosolids cake uniformly
distributed throughout the treated biosolids. 6.1.5.2 Biosolids with a high moisture content may require
6.1.1.1 Biosolids with a high moisture content will require
a higher dose ratio than drier dewatered biosolids cake when
less mixing energy than high-solids biosolids cake. dosage ratios are expressed on a dry weight basis.
6.1.1.2 Biosolids characteristics will determine the proper
6.1.6 Reaction Time and Curing Time:
type of equipment or system required for adequate mixing.
6.1.6.1 Heatwillbegeneratedashydrationofcalciumoxide
Incomplete mixing can cause odor release during product
occurs. The reaction time will vary depending on reagent
storage or application and may lead to failure to meet regula-
composition moisture content of the biosolids mass, and mixer
tory requirements for pathogen and vector control.
efficiency.
6.1.2 Particle Size:
6.1.6.2 Reaction times to effect pathogen reduction are
6.1.2.1 Given an adequate moisture supply using alkaline
established by applicable federal and state regulations.
agents (for example, CaO) with smaller particle sizes will
Reaction/cure times depend upon a number of variables and
facilitate rapid and efficient mixing of agents with biosolids
should be pilot-tested using the actual biosolids cake, alkaline
and increase reaction rates and pH, resulting in higher tem-
admixture, mix unit, cure vessel, and testing protocol and
peratures and greater pathogen reduction.
acceptance criteria to assure compliance with regulatory stan-
6.1.2.2 Since dusts are more easily generated from finely
dards.
divided particles, precautions should be taken to prevent
6.1.6.3 For alkaline treatment processes, one of the three
exposure to eyes and mucous membranes, which may result in
performance criteria is required:
irritation.
(1)The time-temperature relation established in 40 CFR
6.1.2.3 Reactivity and particle size also affect the rate of
503.32 (a) (3) (Alternative 1). Selected time-temperature
dust and mist emissions from reactors or mixing devices, or
values are as follows:
both.Particulatereleasemayrequirescrubbing,waterspray,or
other emission controls on reactors or mixing devices for
Biosolids Temp, °C 50 55 60 65 70 75 80
Moisture >7 % Time, hours 316 63 13 2.5 0.5 0.10 0.020
aesthetic reasons or to meet regulatory requirements.
Moisture <7 % Time, hours 120 24 4.8 0.95 0.19 0.04 0.008
6.1.2.4 Very small particle size may also lead to “air
slaking”orrecarbonationofactivelimeparticlesifthematerial (2)ThepH-time,temperature-time,dryingprocedurein40
CFR 503.32 (a) (4) (Alternative 2). Basically, the biosolids are
is exposed to high humidity.Air slaked/recarbonated materials
will not achieve the pH necessary to meet regulatory require- held at a pH above 12 for 72 hours with a 12-hour period in
ments. whichthetemperatureexceeds52°C,followedbyairdryingto
6.1.3 Reactivity (Heat and pH Elevation): a solids content exceeding 50%.
D6249 − 06 (2011)
(3)Pasteurization (40 CFR 503, App. B, Part B—PFRP 6.1.10.1 Product utilization may be affected by solids con-
Option 7) in which the biosolids are maintained at a minimum tent to aid in control of microbial regrowth during storage to
minimize odor potential at application sites and during storage
temperature of 70°C for 30 minutes.
ortoimproveend-productmarketabilityandphysicalhandling
6.1.6.4 Ammonia or other odors released may require water
characteristics.
spray, scrubbing, gas capture, or control of emission.
6.1.11 On-Site Storage:
6.1.7 Reaction/Cure Vessels or Containers:
6.1.11.1 On-site storage may be required for a land appli-
cation or marketing program of the tested product. Programs
6.1.7.1 Consideration should be given to minimize heat
that produce an end-product for sale should consider on-site
losses through materials management, configuration, and ma-
storage capacity to meet the seasonal fluctuations in market
terials of construction for processes that require extended
demand,theschedulingneedsoftheconsumer,andproduction
curing times.
rates of the generator.
6.1.7.2 Proper temperatures can be maintained without an
6.1.11.2 On-site storage may require odor control for end-
insulated vessel by adding adequate alkaline reagent to com-
products with high moisture content or a low alkaline reagent
pensate for heat loss. However, some situations may benefit
dosage rate.
from an insulated vessel to efficiently retain the heat to meet
6.2 PSRP (Class B) Alkaline Treatment of Biosolids:
PFRP temperature requirements.
6.2.1 Mixing—Thoroughmixingofthebiosolidsandchemi-
6.1.7.3 For processes using a windrow, at a minimum, the
calreagentmustbeprovidedtoensureuniformpHdistribution
mixtureshouldbeatleast18inchesthickatalllocationsinthe
and pathogen reduction (2). Mechanical mixing to achieve a
pile to ensure heat retention throughout the entire mass for the
homogeneous blend of reagent throughout the biosolids mass
applicablecuringtime.Thinareasatthepileextremitiesshould
depends upon a number of factors, including achieving the
beavoidedastheywillnotretainadequateheatandcanleadto
proper ratio of alkaline reagent to biosolids, and sufficient
potential regrowth and recontamination of the entire mass.
moisture to enable the reaction to occur.
6.1.8 Process Testing Requirements: 6.2.1.1 Incomplete mixing or an inadequate reagent dosage
rate can cause odor generation and release during product
6.1.8.1 Process testing requirements vary with the specific
storage or application and failure to meet regulatory pathogen
alkaline process selected.
or vector control requirements.
6.1.8.2 Temperature and pH measurements for the requisite
6.2.2 Alkaline Reagent Particle Size:
time periods should be recorded to comply with pathogen
6.2.2.1 Reactions occur as the alkaline reagents contact the
reduction (and vector attraction reduction). Daily testing may
moist biosolids particles. The rate of reaction of the alkaline
include monitoring and documenting the elevated temperature
reagent tends to increase with: (1) finer reagent particle size,
and pH for a predetermined period of time (see 6.2.6 for
and (2) increased free moisture content. Reagents with a finer
details). Some methods also require documentation of reduced
(smaller) particle size distribution generally are more easily
moisture content and mixing.
and uniformly blended into the biosolids.
6.1.8.3 Procedures to monitor or collect samples for analy-
6.2.2.2 When using an alkaline slurry, or treating liquid
sis are developed for each project based upon site-specific
biosolids, particle size may not be as critical as long as
conditions considering the process selected, equipment sufficient mixing and reaction time are provided.
6.2.3 Reactivity (pH elevation):
utilized, volumes of materials to be processed, local state and
6.2.3.1 Caremustbetakentoensuremoisturewillnotcome
federal regulatory requirements, and local conditions (3).
into contact with the reagent prior to entering the mixer. Air
6.1.9 Process Testing Schedule:
slaking of the alkaline reagent can be a problem in long-term
6.1.9.1 Testing must be conducted in accordance with
storage or pneumatic transfer systems. Guidance for proper
federal, state, and local regulations. Product testing, to meet
storage of reactive alkaline materials can be found in Lime—
end-userequirements,willbesite-specific.Under40CFRPart
Handling,Application and Storage, National LimeAssociation
503 regulations, pathogen (salmonella, virus, protozoan, and
Bulletin 213.
helminth egg) or indicator organism testing and pollutant
6.2.3.2 Increasing the alkaline reagent oxide concentration
concentration (metals) testing requirements are:
may increase potential for reactivity.
Amount
...