United States
Environmental Protection
Agency
Office Of Water
(4203)
EPA 833-B-89-100
August 1989
&EPA
POTW Sludge Sampling And
Analysis Guidance Document
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TABLE OF CONTENTS
ACKNOWLEDGEMENTS ............................................ vi
1. INTRODUCTION ........................................... 1-1
2. SLUDGE SAMPLING ....... ... ................................ 2-1
2 . 1 BACKGROUND INFORMATION ............................ 2-1
2.1.1 Solids Content and Viscosity ............... 2-1
2.1.2 Processed Sludge Characteristics ........... 2-2
2.1.2.1 Anaerobically Digested Sludge ..... 2-2
2.1.2.2 Aerobically Digested Sludge ....... 2-3
2.1.2.3 Dewatered Sludges ................. 2-3
2.1.2.4 Compost Product ................... 2-3
2.1.2.5 Dried Powder ..... ................. 2-3
2 . 2 SAMPLE POINT SELECTION ............................ 2-4
2.2.1 General Considerations ..................... 2-4
2.2.1.1 Sample Point Representation of
the Entire Sludge Stream. ......... 2-4
2.2.1.2 Availability of Flow Data and/or
Solids Data ....................... 2-7
2.2.2 Sludge Sample Points ....................... 2-8
2 . 3 SAMPLE COLLECTION ................................. 2-8
2.3.1 Sampling Equipment ......................... 2-11
2.3.2 Proper Sampling Practices .................. 2-12
2.4 SAMPLE SIZE, SAMPLE TYPE, AND SAMPLING FREQUENCY.. 2-14
2 . 5 SAMPLE PREPARATION AND PRESERVATION ............... 2-19
2.5.1 Sample Container Material .................. 2-20
2.5.2 Sample Container Preparation ............... 2-20
2.5.3 Sample Preservation ........................ 2-21
2.5.4 Holding Time Prior to Analysis ............. 2-22
2 . 6 PACKAGING AND SHIPPING
2.6.1 Packaging .................................. 2-22
2.6.2 Transportation Regulations ................. 2-22
111
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TABLE OF CONTENTS (Continued)
3.
4.
5.
6.
A.
B.
2 . 7 DOCUMENTATION
2.7.1 Sample Labeling
2.7.2 Chain-of -Custody
2.7.3 Sampling Log Book
2 . 8 SAFETY CONSIDERATIONS
ANALYTICAL PROCEDURES
3 . 1 CONVENTIONAL AND INORGANIC POLLUTANT PARAMETERS . . .
3 . 2 METALS
3.2.1 Analyte Isolation/Preparation Overview
3.2.2 Analytical Techniques for Metals
3.2.2.1 Sample Preparation/Digestion
3.2.2.2 Analytical Detection Methods
3 . 3 ORGANICS
3.3.1 Overview of Analyte Extraction and
Isolation
3.3.2 Recommended Analytical Techniques for
Organics
3.3.2.1 Methods 1624C and 1625C
3.3.2.2 Methods 62 4 -S and 625-S
3 . 4 PATHOGENIC MICROORGANISMS
QUALITY ASSURANCE .' .
SAMPLING AND ANALYTICAL COSTS
5 . 1 MANPOWER REQUIREMENTS
5 . 2 IN-HOUSE ANALYTICAL COSTS
5 . 3 CONTRACT ANALYTICAL COSTS
5 . 4 SAMPLING EQUIPMENT COSTS
5.5 Opportunities for Cost Savings
REFERENCES
APPENDIX A: Chain of Custody Perm
APPENDIX B: Determination of Volatile Solids Reduction.
Page
2-24
2-24
2-26
2-27
2-27
3-1
3-2
3-6
3-6
3-8
3-8
3-9
3-18
3-13
3-22
3-22
3-25
3-26
4-1
5-1
5-1
5-2
5-4
5-4
5-7
6-1
A-l
B-l
IV
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LIST OF TABLES
Table Page
2,1 Sludge Flow Measurement Devices 2-9
2 .2 Sludge Sampling Paints 2-9
2.3 Containers, Preservation, Holding Times, and Minimum
Sample Volume 2 -15
2.4 Potential Interferences Associated with Sampling
Shipping and Storage 2-23
2.5 Standard Preservatives Listed in the Hazardous
Materials Table (49 CFR 172.101) Used by EPA for
Preservation of Water, Effluent, Biological, Sediment
and Sludge Samples 2-25
3,1 Analytical Techniques for Conventional and Inorganic
Pollutants in Sludge 3-3
3.2 Recommended Preparation Technique for Elemental
Analysis of Sludge Samples 3-10
3 . 3 Comparison" Summary of ICAP and AAS 3-12
3.4 Recommended Inductively Coupled Wavelengths and
Estimated Instrumental Detection Limirs 3-14
3.5 Atomic Absorption Flame and Furnace Instrumental
Detection Limits for Wastewater Samples 3-16
3.6 Analytical Techniques for Determination of Pathogenic
Microorganisms in Sewage Sludge 3-29
5 .1 Sampling Manpower Needs 5-2
5.2 Typical Contract Analytical Costs for Commonly
Analyzed Sludge Parameters 5-5
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ACKNOWLEDGMENTS
This guidance document was completed under the direction of
Cristina Morrison, of the U.S. EPA's Office of Water Enforcement
and Permits (OWEP), with assistance from Tom Wall, also of OWEP.
This document was prepared by Science Applications International
Corporation (SAIC) under EPA Contract No. 68-01-7043. The
document was revised to address peer review comments under EPA
Contract No. 68-C8-0066.
The SAIC WorJc Assignment Manager was Werner H. Zieger.
Significant contributions were made by Jorge McPherson, John
Sunda, and MarJc Xlingenstein.
This document has been peer reviewed. EPA wishes to
acJoiowiedge the valuable review and comments provided by the
following entities:
o EPA Region 3
O EPA Region 5
o EPA Region 9
o EPA Region 10
o EPA Environmental Monitoring Support Laboratory
O AMSA
o California State Water Resources Control Board
o Connecticut Department of Environmental Protection
o Eli Lilly and Company
o Eugene Oregon Public Works Department
o LA County Sanitation District
o Missouri Department of Natural Resources
o Nampa, Idaho Wastewater Division
o Ohio EPA
o Unified Sewerage Agency of Washington County
o John F. Morrison, P.E., American Society of Quality
Control Engineers
vi
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1. INTRODUCTION
The passage of the 1987 amendments to the Clean Water Act
brought about significant changes in the regulation of the use
and disposal of municipal sewage sludge. Although the Clean
Water Act had required since 1977 that EPA develop technical
standards for sludge use and disposal, the 1987 amendments
required that these standards, when promulgated, be implemented
through permits. The amendments also state that prior to
promulgation of the technical standards, EPA must include sludge
conditions in NPDES permits issued to publicly-owned treatment
works or take other appropriate measures to protect public health
and the environment from pollutants in sewage sludge. This
requirement has initiated a program for "case-by-case" permitting
to ensure protection of the environment prior to the issuance of
final sludge standards which are scheduled for promulgation in
October 1991.
This focus on sludge permitting places increased emphasis on
the need to assess sewage sludge quality. In policy and guidance
documents that EPA has developed for implementing the sludge
requirements of the Clean Water Act, the Agency has recommended
that POTWs sample and analyze their sludge at least annually to
determine if the sludge quality is such that the sludge may be
safely reused and recycled or disposed. Accurate character-
ization of sludge composition spots operational problems at the
treatment works and may also signal adverse environmental
impacts. In addition, sludge sample and analysis is needed to
assess compliance with current requirements (e.g., 40 CFR Part
257 requirements for cadmium and PCBs).
1-1
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In view of the variability of municipal sludge quality,
appropriate procedures must be followed to collect and analyze
samples that accurately represent each POTW's sludge quality.
This manual was developed to provide that guidance to POTW
operators, engineers, managers, chemists and permit writers. It
was intended to provide guidance in developing and implementing a
sampling and analysis program, to gather information on sludge
quality and determine compliance with permit conditions. This
manual is based on current, state-of-the-art field and laboratory
practices and therefore is recommended for all sludge sampling
and analysis programs.
1-2
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2. SLUDGE SAMPLING
2.1 BACKGROUND INFORMATION
Depending on the use or disposal practice, it may be
necessary to sample various sludge types throughout a given POTW.
In order to sample a sludge stream effectively, it is necessary
for sampling personnel to be aware of the physical
characteristics of the sludge stream!s) at intended sampling
locations.
2.1.1 Solids Content and Viscosity
Two important physical characteristics of sludge with
respect to sampling and analysis are viscosity and solids
content. Solids content is the percent, by weight, of solid
material in a given volume of sludge. Sludges have a much higher
solids content than most wastewaters. Solids content and solids
settling characteristics determine whether a given sludge will
separate into different fractions which increases the potential
of obtaining a nonrepresentative sample.
Viscosity is the degree to which a fluid resists flow under
an applied force. The viscosity of a sludge is only somewhat
proportional to solids content. This property affects the
ability to automatically sample a liquid, since friction through
pipes is proportional to liquid viscosity. In general, sludges
of up to 20 percent solids may be conveyed by means of a pump.
Sludge with a greater solids content, often referred to as sludge
cake, must be conveyed by mechanical means. Automatic samplers
that rely on pumps may be useful only for liquid sludges with a
solids content of less than 20 percent. However, sludge caJces
require manual grab sampling. Other problems created by sludge
2-1
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solids (see Section 2.3.1) generally preclude the use of auto-
matic samplers.
Solids content is also significant from an analytical stand-
point. Increased solids content may require sample dilution and
cause a corresponding increase in experimental error and
detection limits. Also, water removal through dewatering can
either concentrate parameters of interest in the sludge and
increase analytical accuracy, or carry away pollutants and
decrease pollutant concentration and analytical accuracy.
Analytical precision (repeatability) and accuracy (closeness to
true value) may also decrease as the concentration of interfering
compounds and matrix effects increase, due to higher solids
content after dewatering.
2.1.2 Processed Sludae Characteristics
The quantity and quality of sludge generated depends on raw
wastewater characteristics and the sludge treatment practices.
The sludge to be sampled may be in the form of a liquid,
dewatered cake, compost product, or dried powder. Some of the
physical characteristics of each sludge type are described below.
2.1.2.1 Anaerobically Digested Sludge
Anaerobically digested sludge is a thick slurry of
dark-colored particles and entrained gases. When Well digested,
it dewaters easily and has a non-offensive odor. The addition of
chemicals coagulates a digested sludge prior to- mechanical
dewatering. The dry residue of digested sludge contains 30 to 60
percent volatile solids. Depending on the mode of digester
operation, the percent solids of digested sludges ranges from 4
to 8 uercent.
2-2
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2.1.2.2 Aerobically Digested Sludge
Aerobically digested sludge is a dark-brown, flocculent,
relatively inert waste produced by long-term aeration of sludge.
The suspension is bulky and generally difficult to thicken. The
odor of aerobically digested sludge is not offensive. The
percent solids of aerobically digested sludge is less than that
of the influent sludge (if not decanted), because approximately
50 percent of the volatile solids are converted to gaseous end
products during aerobic digestion.
2.1.2.3 Dewatered Sludges
Dewatering converts sludge from a flowing mixture of liquids
and solids to a cake-like substance more readily handled as a
solid. The characteristics of dewatered sludge depend on the
type of sludge, chemical conditioning, and treatment processes
employed. The percent solids content of dewatered cake ranges
from 15 to >40 percent. Cake with a lower percent solids is
similar to a wet manure, while cake with a higher percent solids
is a chunky solid.
2.1.2.4 Compost Product
Composting is a process in which organic material undergoes
biological degradation to a stable end product. Properly
composted sludge is a sanitary, nuisance-free, humus-like
material containing 75 to 80 percent solids. Approximately 20 to
30 percent of the volatile solids are converted to carbon dioxide
and water.
2.1.2.5 Dried Powder
Dried powder is the residue from heat drying processes.
Sludge drying reduces water content by vaporisation of water TO
permit sludge grinding, weight reduction, and to prevent
2-3
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continued biological action. The moisture content of dried
sludge is less than 10 percent.
Incinerator ash is a product of the incineration of sewage
sludge. Ash is therefore not covered under the sampling or
analysis of sewage sludge. It is covered under RCRA Subtitle C
if it is a hazardous waste and if not it falls under Subtitle D.
2.2 SAMPLE POINT SELECTION
2.2.1 General Considerations
NPDES, pretreatment and sludge program officials need sludge
quality data in order to determine whether sludge use or disposal
may pose a threat to public health or the environment. Thus, as
a general rule, sludge samples should be drawn from an
appropriate sampling point and in such a manner that the sample
represents, as well as possible, the quality of the sludge as it
will be disposed of or used. When selecting a specific sample
point, the following two factors should be carefully considered:
o Does the sample point represent the entire sludge
stream?
o Are the sludge stream flow or mass flux data available?
The following paragraphs examine both factors and present
recommendations on means to address each factor.
2.2.1.1 Sample Point Representation of the Entire Sludge Stream
Often it is not possible to obtain a wholly representative
sample of a given wastestream at any one time. Effort must be
made, however, to ensure that a sample is obtained that is as
representative as possible. Three concerns that need to be
2-4
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addressed to ensure that the sample points selected will provide
representative samples of the entire sludge stream are:
obtaining samples that are representative of the cross-section of
the entire flow; obtaining well mixed samples; and obtaining
samples of multiple sludge streams.
A particular concern in any sampling program is to obtain
samples which represent the entire flow past the sample point
throughout the sample period. Each discrete sample should
represent the cross-section of the entire flow at the sampling
point. Each composite sample of multiple contributory streams
should represent the cross-section of the entire flow of the
combined stream.
Samples should be obtained from points where the sludge is
well-mixed. While some pollutant parameters are predominantly
associated with the solids fraction (particularly precipitated
metals), others are more associated with the liquid-fraction
(many dissolved organics). Failure to acquire a sample with
representative solid/liquid fractions can significantly affect
the analytical results of a given sample. This is particularly
true of sludge streams with high percent solids and large flee
particles. Since turbulence ensures mixed samples, these
recommendations should be followed:
In sludge processing trains, samples from taps on the
discharge side of sludge pumps are well mixed since
flow at this point in the system is turbulent with no
solids separation within the flow stream.
If a sample is drawn from a tap on a pipe containing
sludge which is distant from the sludge pumps, the
average flow velocity through the pipe should be
greater than 2 feet per second (fps). Average
velocities of less than 2 fps result in solids
separation and settling, and affect sample solids
content, depending on the location of the tap (top,
2-5
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side or bottom of the pipe). Given a choice, a tap on
the side of the pipe is preferable. In addition, the
tap should be a large size to encourage draw from the
entire cross-section of flow when fully open.
At times it may be necessary to sample a poorly mixed open
channel flow. if this cannot be avoided, then each sample must
be a composite consisting of grabs taken at several levels (1/4,
1/2 and 3/4 depth, for example) in order to minimize sample bias
caused by solids stratification. For sampling solid sludges
(i.e. dewatered cake, compost, etc.), stratification can be
avoided by not only sampling at various depths, but at numerous
locations over the entire sludge pile.
Although it is preferable to sample sludge just prior to its
exit from the treatment plant in a combined stream, sometimes
that is not possible. Therefore, a consideration in many sludge
sampling situations is the need to produce a composite sample
from confluent streams. An example is the sampling of sludge
flows from several parallel sources which later combine
downstream in an unsafe or inaccessible location. Several
options exist to accommodate multiple streams. The most
appropriate choice depends on the sludge flow and solids flux
information available, the parameters being sampled and the
purpose of the generated data. Several options are as follows:
o The simplest option is to withdraw equal volumes of
sample from each of the multiple sludge streams to
create a composite sample. This approach is justified
in the case of identical units receiving equal flow and
generating equal sludge amounts.
o A second option is to weight the grab samples in each
composite according to the wastewater flow to each unit
(or in the case of filter cake, the thickened sludge
flow to each unit). This approach recognizes that for
different sized units with different design flows, the
volume of sludge produced win theoretically be
2-6
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proportional to the influent flow to the unit.
However, factors such as unequal loading rates,
differences in sludge collection mechanisms, etc. can
affect solids removal rates and sludge generation rates
by unequal, parallel treatment units. This option
particularly applies to situations where no sludge flow
or solids data exists for unequal parallel flow
streams.
o The third option is to weight grabs from individual
streams based on sludge flow data or solids flux data.
Whether to use sludge flow or solids flux will depend
on the sample streams, the parameters of interest, and
the planned use of the resulting data. For example, if
filter cake is being monitored for compliance with land
application limits, solids flux data would be used as
the criteria for proportioning grabs from parallel
dewatering systems, since most land application limits
are based on dry weight application rates.
2.2.1.2 Availability of Flow Data and/or Solids Flux Data
The availability of accurate solids flux data (weight/time/
or accurate flow data (volume/time) is an important consideration
in planning a sludge sampling program. Most information
requirements relating to sludge characteristics involve, at least
in part, the need for data on the solids flux of pollutant
parameters found in sludge discharged from a POTW. The percent
solids should be determined on sludge samples.
Portable flow monitoring devices are not well suited to
high-solids flow streams, and most sludge processing streams are
not designed in a manner which is physically conducive to the use
of these devices. Thus, in most cases, it is necessary to rely
on existing integrated flow monitoring equipment. Due to
difficulties in monitoring sludge flows, flow meters are high
maintenance items. Frequent calibration of sludge flowmeters is
necessary in order to ensure accurate flow measurement. This
data should be cross-checked agair.it mass balance data. When
ultimate use or disposal practices dictate monitoring sludge with
2-'
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a high solids content, liquid flow meters are replaced, by gross
weight scales. TaJDle 2.1 summarizes the types of flow
measurement equipment employed to monitor various sludge flows.
2.2.2 Sludae Sample Points
The determination of the appropriate sludge sanpling point
is dependent on the rationale behind the sampling. For permits
and regulation enforcement, sludge samples must come from the
treatment unit process immediately preceding disposal or use.
For example, if a POTW disposes of its dewatered filter cakes in
a sanitary landfill, then sampling activity focuses on the output
sludge stream from the dewatering device (i.e., vacuum filter,
belt filter, etc.). The sludge treatment processes commonly
employed are stabilization, dewatering, drying, composting, and
thermal reduction. Table 2.2 summarizes sampling points for
these processes. Other sludges sampling points may be necessary
to examine the origin or fate of pollutants within a POTW, (i.e.,
additional sludge samples from influent and output of other
processes may be needed).
2.3 SAMPLE COLLECTION
Having selected appropriate sampling points for a sludge
sampling program, it is then, necessary to determine the method
and equipment by which sampling vill be-carried out. In doing
so, the following objectives should be considered:
o Each grab sample, or aliquot of a composite sample,
must be as representative as possible of the total
stream flow passing the sampling point
o Effort must be made to minimize the possibility of
sample contamination
o The selected sampling method should be safe, convenient
and efficient.
2-8
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TABLE 2.1. SLUDGE FLOW MEASUREMENT DEVICES
Application
Measurement Means
Stabilized Sludge
Thickener
Dewatering
Drying
Composting
Thermal Reduction
Venturi
Flow Tube
Magnetic Meter
Positive Displacement Pump
Magnetic Meter
Positive Displacement Pump
Belt press scales
Bulk container or truck scales
TABLE 2.2. SLUDGE SAMPLING POINTS
Sludae Type
_5ampling Point
Anaerobically
Digested -
Aerobically
Digested -
Thickened
Sludaes -
Sample from taps on the discharge side of
positive displacement pumps.
Sample from taps on discharge lines from pumps.
If batch digestion is used, sample directly
from the digester. Two cautions'are in order
concerning this practice:
(1) If aerated during sampling, air .entrains in
the. sample. Volatile organic compounds may
purge with escaping air.
(2) When aeration is shut off, solids separate
rapidly in well digested sludge.
Sample from taps on the discharge side of
positive displacement pumps.
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TABLE 2.2.
SLUDGE SAMPLING POINTS
(continued)
Sludoe Type
Sampling Point
Heat Treatment
Dewatered, Dried,
Composted, or
Thermally Reduced
various depths.
Dewatered:
Sample from taps on the discharge side of
positive displacement pumps after decanting.
Be careful when sampling heat treatment
sludge because of:
(1) High tendency for solids separation
(2) High temperature of sample
(frequently >60°C as sampled) can
cause problems with certain sample
containers due to cooling and
subsequent contraction of entrained
gases.
Sample from material collection conveyors
and bulk containers. Sample from many
locations within the sludge mass and at
Belt Filter Press,
Centrifuge, Vacuum
Filter Press
Sludge Press
(plate and frame)
Drying Beds
Compost piles
Sample from sludge discharge chute.
Sample from the storage bin; select
four points within the storage bin,
collect equal amount of sample from
each point and combine.
Divide bed into quarrers , grab equal
amounts of sample from the center of
each quarter and combine to form a
grab sample of the total bed. Each
grab sample should include the
entire depth of the sludge (down to
the sand) .
Sample directly from front-end
loader as the sludge is beinc loaded
into trucks to be hauled awav.
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Except for limitations on the use of automatic sampling
devices, the actual .sampling techniques for sludges are similar
to those found in wastewater sampling. The following sections
describe two important considerations for selecting appropriate
sludge sampling methods: sampling equipment and proper sampling
practices.
2.3.1 Sampling Equipment
In general, automatic sampling devices, which are widely used
for wastewater streams, do not work well for sludge streams
because of the solids content and viscosity of sludges.
Automatic samplers which use pumps to draw samples up a suction
tube cause solids separation if flow velocity in the suction and
discharge tube is too low. This increases pump head requirements
and limits the range of tubing diameter. A second problem which
occurs in the use of automatic samplers is fouling of tubing
and/or pump structure by sludge solids. This results in
contamination of subsequent aliquots during composite sampling.
Sludge particles may also plug the sample tube or pumpjing
mechanism and interrupt sample collection. Therefore, it is
preferable to sample liquid sludge streams manually, particularly
if sample taps can be provided on pump discharge lines.
Sampling equipment must be made of materials which will not
contaminate or react with the sludge. ' The best material choices
are Teflon, glass, and stainless steel because they are
relatively inert. When the cost of Teflon and stainless steel
equipment prohibits or restricts their use, plastic, steel and/or
aluminum may be substituted for most sampling activities. (If
steel equipment is used, ensure that galvanized or zinc coated
items are not used because these materials will readily release
zinc into the sample.)
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Graduated glass or plastic pitchers or cylinders are used to
draw gratis for manually composted samples. Stainless steel
pitchers are also commercially available, and are used to gra_b
samples from taps and also can be affixed to lengths of conduit
to sample from open channel flows. Only aluminum conduits should
be used since most commercially available steel conduit is
galvanized. In addition, only stainless steel clamps should be
used to attach the sample container to the conduit.
2.3.2 Proper Sampling Practices
Listed below are practices that should be followed when
sampling sludges:
o Clean all sampling equipment between each sample period
to prevent cross-contamination. Cleaning consists of
thorough washing with a laboratory detergent, thorough
rinsing with tap water and then with at least three
distilled water rinses.
o Sample aiiquots should be composted directly into
sample containers. Sample containers, preservation of
sample and allowable holding time prior tc analysis are
discussed in Section 2.5.
o When collecting samples for oil and grease analysis,
sample directly into the sample container since oil and
grease tend tc adhere to surfaces. Sample composites
should be sent to the laboratory as a series of grab
samples.
o Sample collection procedures should be adequately
documented, as discussed in Section 2.7.
o When collecting samples for organic volatiles or semi-
volatiles, carefully pour liquid sludge into container
so as to avoid entrapping air within sample. Fill
container to overflowing and screw on lid. Check air
bubbles by turning container upside down and tapping
lid. If air bubbles rise, open container and fill with
additional sample. For sludge cake, care-fully pack
sludge in:o container so as to avoid air spaces. Fij.1
the container to overflowing and screw on lid.
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When collecting samples for dioxin/furan, fill the
container to 4/5 full to enable expansion of samples
when they are frozen.
When collecting samples for pesticides/PCBs/herbicides,
metals and nonconventionals, fill container to within
1/2 inch of the top to provide room for expansion
should there be any gas production during sample
shipment.
When sampling liquid sludges:
To draw a fresh representative sludge sample from a
tap:
a) Allow sufficient time following pump start up to
clear line of stagnant sludge, and
b) Allow sludge to flow for several seconds from tap
prior to sampling in order to flush out stagnant
sludge and solids accumulated in the tap.
Before drawing a sludge sample, rinse each piece of
sampling equipment 3 times with sample to reduce the
chance of contamination from the previous grab.
To prevent solids separation in the sample, use glass,
Teflon-coated stirring rods, or stainless steel spoons
to mix the sample before splitting or transferring any
portion of. it to another container (s).
When sampling solid sludges:
For either dewatered cakes, dried powder or compost
product, combine equal amounts collected"at various
locations/depths for each grab sample to obtain a more
representative sample.
a) To produce a sample from multiple sample locations
(e.g. , two or more dewatering units) , combine the
grab samples from each location (equal amounts or
weighted based on flow or solids flux data) in a
plastic or stainless steel pail and thoroughly mix
the sample (with a scoop or spoon) , then transfer
it to sample containers. This is not appropriate
for volatile or microbial samples.
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b) When sampling drying beds, divide each bed into
quarters. From the center of each quarter,
collect a single core sample through the entire
depth of the sludge using a coring device.
Usually a small amount of sand will be collected;
avoid large amounts of sand. Combine and
thoroughly mix in plastic or stainless steel pail
and transfer to sample containers.
2.4 SAMPLE SIZE, SAMPLE TYPE, AND SAMPLING FREQUENCY
Sample Size
A proper sample is small enough to transport conveniently
and handle carefully in the laboratory, but large enough to
accurately represent the characteristics of the whole material.
Minimum sample sizes required for accurate analysis are specified
in each analytical method. Table 2.3 lists minimum sample sizes
for some common analytical methods. For methods not listed here,
consult an analytical methods reference or the laboratory for
further guidance.
Sample Type
A grab sample collected at a particular time and location
can represent the composition of the source only at that time and
location. In the case of most sludges, single grab samples will
adequately represent only the instantaneous composition of the
material being sampled. The quality of a grab sample will be
improved if it is comprised of several smaller samples taken over
a period of a few minutes.
A composite sample gives a better reflection of the time-
and location-weighted average concentrations that are found in
the sludge flow stream. In most cases, the term "composite
sample" refers to a mixture of grab samples collected at the s. Tie
sampling point at different times. Although a 24-hour composite
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TABLE 2.3
CONTAINERS, PRESERVATION, HOLDING TIMES, AND MINIMUM SAMPLE VOLUMES
(I)
Parameter
Inorganic Compounds
Asbestos
Metals
Chromium VI
Mercury
Medals except above
Organic Compounds
Extractables (including
phthalates, nitrosamines ,
Wide-mouthed
Container
P,
P,G
P,G
P,G
G, teflon-
lined cap
/2)
Preservative
None
Cool , 4°C
HN03 to pH<2
HNO3 to pH<2
Cool, 4°C
0.008% Na?S?0.
Maximum . . Minimum
Holding Time( ' Sample Volume1
None
24 hours
28 days
6 months
7 days (U(a>
40 days lcu
2000 mL
300 mL
500 mL
1000 mL
1000 mL
nitroaromatics, isophorone,
polynuclear aromatic HC,
haloethers, chlorinated
HC and TCDD)
Extractable (phenols)
Purgeables (Halocarbons
and Aromatics)
Purgeab1es
(Acrole in and
Aery Ion i t.r i le)
P, for
dioxin and
furan only
G, teflon-
1 i ned c:ap
G,, teflon
lined sept.a
G, i.eflou
1 int'id sepi
°
Cool, 4C
H2S04 to pH<2
0.008% Na2S203
Cool 4°C
0.008% Na S203
1 ; 1HC1 to pH 2
4°C
Coo 1
0.008% Na.,3
pli i:o 4 or
40 days
7 days (w/0>
14 days in
darkness
1.4 days
1000 mL
>20 mL
>20 mL
-------
TABLE 2.3 (Continued)
CONTAINERS, PRESERVATION, HOLDING TIMES, AND MINIMUM SAMPLE VOLUMES(1)
Wide-mouthed . Maximum Minimum
Parameter Container Preservative Holding Time* Sample Volume
Pesticides & PCBs G, teflon- Cool 4°C 7 days (u* 1000 mL
lined septa 0.008% Na2S203 40 days
(1) 40 CFR Part 136
(2) Preservatives should be added to sampling containers prior to actual sampling
episodes. Holding times commence upon addition of sample to sampling container.
Shipping of pre-preserved containers to the sample sites may be regulated under DOT
hazardous materials regulations. Shipping of preserved samples to the laboratory
is generally not regulated as a hazardous material.
(3) Varies with analytical method. Consult 40 CFR Part 136,
P = Plastic (Polyethylene)
G ^ Glass (Non-etched Pyrex)
(a) After extraction
(u) Before extraction
(w/o) Without preservatives
-------
sample (consisting of a number of time- or flow-weighted grab
samples) is more representative than a grab sample, it can give a
picture of only one day's sludge quality. Historical data is
necessary to truly represent the sludge quality. A composite for
volatile components analysis is produced in the lab from grab
samples collected in the field.
Sampling Frequency
As sludge quality is directly related tc wastewater influent
quality (which can vary from day to day and hour to hour), a POTW
should sample and analyze its sludge frequently to obtain
representative data. Collection of representative sludge data is
crucial because the permitting authority will use the resultant
analytical data to establish permit monitoring parameters and
frequencies, and thereafter, to assess compliance with the permit
and to ascertain if there is a potential for adverse environ-
mental impacts. POTW operators should be aware that EPA's
"Strategy for Interim Implementation in Permits Issued to POTWs"
(draft June 1988) to be finalized during the fourth quarter of
1989) sets forth minimum recommended monitoring frequencies to be
included in the MPDES permit when it is reissued. The Interim
Strategy is scheduled to be finalized in the summer of 1989. The
NPDES permit writer may decide based on his/her best professional
judgment (BPJ) that more frequent monitoring is needed. The
sampling frequency will be set out in the POTWs permit.
To the extent practicable, the POTW should have a sludge
sampling program which adequately addresses random and cyclic
variation within the system and the potential for human exposure
to sludge once it is disposed of or used.
o Anticipated cyclical variation in pollutant loadings -
although they are difficult tc accurately predict,
anticipated cycles include daily industrial production
2-17
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cycles, weekly industrial production cycles, and other
known or suspected production cycles, particularly
those associated with intermittent batch discharges by
significant industries. Longer-term production cycles,
including seasonal and annual/multi-year production
cycles (e.g., business cycles), do not need to be
considered in determining monitoring frequency unless
they are known to affect short-term variation in sludge
quality.
o Risk of environmental exposures - As the risk of
environmental exposure from sludge use/disposal
increases, a POTW should increase its sampling
frequency to provide better information about potential
variation in sludge quality. For example, a sludge
that is applied to food-chain croplands should be
sampled more frequently than sludge that is disposed of
in a landfill that has an impermeable liner and a
groundwater monitoring system.
Other factors that should be considered in determining
sampling frequency include:
o Size - As influent flow increases, day-to-day sludge
variability increases, as does outflow volume. Thus,
where high volumes exist, the risk of adverse exposure
is higher. Since variability and potential impact are
major considerations, many sampling programs are based
on size alone (e.g. 40 CFR Part 503 proposed rule).
Size is also an easy factor to measure.
o Percentage of industrial flow - while sludge quality
variability is directly related to the individual
characteristics of each POTW, POTWs with little or no
commercial/industrial contributors in the. system can
expect relatively small variation in sludge quality.
POTWs with significant industrial contributions can
expect to have monthly, weekly and even daily variation
in sludge quality.
o Treatment plant characteristics - As either detention
time or mixing increases within a treatment plant,
sampling frequency can be reduced since treatment
processes will effectively composite sludge to a
greater degree. For example, high rate digestion and
storage/blending facilities will provide mechanical
mixing of sludge. Other plant technologie , such as
anaerobic digestion, aerobic digestion and storage,
2-18
-------
provide longer sludge detention, times, enabling greater
mixing through physical processes such as diffusion,
convection, etc. For combined sewer systems, a
sampling strategy may be designed to monitor the
effects of storm events on sludge quality.
Another consideration is the type(s) of information a POTW
wishes to collect. If, for example, a POTW desires to measure
daily variation over a typical week, the POTW may collect and
analyze seven or more 24-hour composite samples for the
pollutant. Similarly, if a POTW wishes to measure variation
within a single day, the POTW may collect and analyze several
grab samples taken at different times during the day.
2.5 SAMPLE PREPARATION AND PRESERVATION
There is the potential for errors of varying severity to be
introduced during sample collection and storage which affect
analytical determinations. To avoid potential errors and
maintain sample integrity, POTW operators should carefully
consider the following:
o Sample Container Material
o Sample Container Preparation
o Sample Preservation
o Holding Time Prior to Analysis.
Table 2.3 lists recommended container materials,
preservatives, holding times, and minimum sample volumes for the
analysis of sludges. For method-specific details concerning all
facets of sample preparation and preservation, consult the
references cited in 40 CFR Part 136, "Guidelines for Establishing
Test Procedures for the Analysis of Pollutants."
2-19
-------
2.5.1 Sample Container Material
The requirements for sample containers are method-specific,
but containers are usually made of Teflon, glass or polyethylene.
Sample containers should be wide-mouthed for sludge sampling,
particularly for solids (cake) sampling. Teflon containers are
typically supplied with Teflon caps. Glass containers frequently
are supplied with caps which can cause sample contamination
(phenol, phthalate compounds). For organic parameters, these
glass container caps should be fitted with Teflon liners;
aluminum liners could be used but they must be fitted precisely
within the circumference of the cap to prevent tearing and
possible sample leakage.
2.5.2 Sample Container Preparation
Proper sample container preparation is necessary to prevent
contamination of the sample by material left from the container
manufacturing process or that has otherwise been introduced into
the unused sample containers. All containers should be washed
with a good quality laboratory detergent, thoroughly rinsed vith
tap water, and then rinsed at least 3 times with distilled water
prior to air drying. Additional container preparations for
analysis of particular parameters are described below:
o Extractable Organics - Use glass containers with
Teflon-lined caps only. Wash containers as above and
rinse with solvent (typically methylene chloride); air-
dry.
o Volatile Organics - Prepare containers by washing and
rinsing as described above, and then bake both vials
and septums at 105°C until dry. Cool in an
organic-free atmosphere.
o Metals - Wash and rinse as described above. Then rinse
with dilute acid !1 part deionized, distilled water to
1 part nitric acid {HNC,}), followed by two rinses with
deionized, distilled water.
2-20
-------
2.5.3 Sample Preservation
Table 2.3 presents U.S. EPA's recommended preservation
protocols. These protocols are primarily intended for effluent
monitoring; however, they are generally applicable to liquid
sludge sampling.
The following are specific recommendations regarding sample
preservation:
o In instances where it is desirable to split one
composite sample into several fractions, each having
incompatible preservation requirements, it is
acceptable to chill the entire sample to 4CC during
compositing. Following the sample period, the
composite is then cautiously mixed and split into
various fractions, each of which is appropriately
preserved. This does not apply to samples for analysis
of volatile, semivolatile or microbial contaminants.
o If processing of microbial samples cannot occur within
one hour of collection, iced coolers should be used for
storage during transport to the lab. Samples should be
held below 10°C during the maximum transport time of 6
hours. Note: these samples must be immediately
refrigerated and processed at the lab within 2 hours of
receipt.
o Whenever possible, sample containers should be
pre-preserved. Thus, grab samples are preserved upon
sampling and composite samples are preserved during
compositing. This is not appropriate, however, when
sampling for metals or pathogens.
o In general, all samples should be chilled ( 4°C) during
compositing and holding.
o For solid sludge samples (cake), adding chemical pre-
servative is generally not useful since the
preservative usually does not penetrate the sludge
matrix. Preservation consists of chilling to 4°C.
o When sampling and holding sludges, particularly
biologically active sludges, gas production in the
sealed container may cause an explosion unless the
pressure is periodically released. This should not be
2-21
-------
done however if volatile or semivolatile pollutants are
to be analyzed.
2.5.4 Holding Time Prior to Analysis
Table 2.3 lists the maximum holding times for various
pollutant samples. Table 2.4 lists some potential interferences
that may affect samples during shipping and storage. There are
many more interferences associated with particular analytical
methods, which are discussed further in chapter 3 as well as in
the particular methodology.
2.6 PACKAGING AND SHIPPING
When analysis will be performed away from the sampling
locale, samples must be packaged and transported.
2.6.1 Packaging
Sample containers must be packaged in order to protect rhem
and to reduce the risk of leakage. Containers should be held
upright and cushioned from shock. In addition, sufficient
insulation and/or artificial refrigerant ("blue ice") should be
provided to maintain a sample temperature of 4°C for the duration
of transportation.
2.6.2 Transportation Regulations
The following guidelines control the shipment of wastewater
and sludge samples:
o Unpreserved normal (i.e., not heavily contaminated)
environmental samples are not regulated under DOT
Hazardous Material Regulations. These samples may be
shipped following the packaging guidelines in Section
2.6.1, and using a commercial carrijr, etc. To assure
proper sample temperature, transit time should be held
to less than 24 hours.
2-22
-------
TABLE 2.4
POTENTIAL INTERFERENCES ASSOCIATED WITH
SAMPLE SHIPPING AND STORAGE
Parameter
Interferences
Prevention
Acidity
Ammonia
Cyanide
Chromium VI
Phenols
Silica
Sulfide
Sulf it.e
Organic
Chemicals
Carbon dioxide loss Fill container completely
Chlorine
Volatilization
Sulfides
Reducing agents
Hydrogen sulfide,
Sulfur dioxide
Oxidizing agents
Aeration, agitation
Aeration, agitation
Photodearadation
Sodium thiosulfate
Fill container completely
Cadmium nitrate, tetrahydrate
Minimize holding time
Aerate
Ferrous sulfate
Avoid freezing
Fill container completely
Fill container completely
Use brown alass container
Other than those addressed by protocols shown in Table 2.3
-------
o When environmental samples are preserved as recommended
(see Table 2.5), they may be shipped as non-hazardous
samples.
The guidelines above assume no material is present in the
samples at concentrations which would result in a "hazardous" DOT
rating. Should hazardous material (as defined by DOT) be
present, DOT regulations concerning packaging, transportation and
labeling must be followed {see 49 CFR Parts 172, 173 and 178). A
material is considered hazardous by DOT if it fails one of the
four characteristic tests of: corrosivity, ignitability ,
reactivity and EP Toxicity [see "Test Methods for Evaluating
Solid Waste, SW 846, 1986 for exact methods]. Municipal sewage
sludges labeled as hazardous are usually from failed EP Toxicity
tests and occasionally from reactivity tests.
2 . 7 DOCUMENTATION
Adequate documentation of sludge sampling activities (1) is
important for general program quality assurance/quality control,
and (2) is required by most monitoring regulations. Proper
sampling activity documentation includes proper sample labeling,
chain-of-custody procedures and a log book of sampling
activities. The number of people in the chain of custody should
be kept to a minimum to limit the possibility of contamination
and to increase accountability.
.
.1 Sample Labeling
It -is important that each sample label include the following
nformation (items in bold text are minimum elements):
o Sampling Organization Name
o Facility Name (being sampled)
o Bottle Number (specific to container
2-24
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TABLE 2.5
STANDARD PRESERVATIVES LISTED IN THE HAZARDOUS MATERIALS TABLE (49 CFR 172.101)
USED BY EPA FOR PRESERVATION OF WATER, EFFLUENT, BIOLOGICAL, SEDIMENT, AND SLUDGE SAMPLES
Sample Type/
Parameter
Preservative
Organic Carbon
Nitrogen Species
Metals, Hardness**
Nitrogen Species
COD, Oil 6. Grease,
P (hydrolyzable)
Organic Carbon
Hydrochloric acid
Mercuric chloride
Nitric acid
Sulfuric acid
PH
commendatioi
<2 ->l
N.A.
<2 - >1
<2 - >1
Quantity of
Preservative Added WT. % of
i Per Liter* Preservative
2
40
5
2
ml of 1:1
mg
ml of Cone. (70%)
ml of 36N
0.
0.
0.
0.
04%
004%
35%
35%
Cyanides
Phenolics
Biological - Fish &
Shellfish Tissue***
Sodium hydroxide
Ortho-phosphoric acid
Freezing 0°C
(Dry Ice)
>12 - <13 2 ml Of ION 0.080-
<4 - >2 to yield desired pH
N.A. N.A. N.A.
A *
Sample dilution must be avoided. The volume of washings must be minimized and any
dilution that does occur must be documented and the data corrected for the dilution.
The sample may be initially preserved by cooling and immediately shipping it to the
laboratory. Upon receipt in the laboratory, the sample must be acidified with cone.
UNO-, to pH<2. At time of analysis, sample container should be thoroughly rinsed
with 1 : 1HNO-, ; washings should be added to sample.
*** Dry ice is classified as an ORM-A hazard by DOT. There is no labeling requirement
for samples preserved with dry icy, but each package must be plainly and durably
marked on at least one side or edge with the designation ORM-A. Advance arrangements
which must be met to ship dry ice are found in DOT regulation 49 CFR 173.616.
-------
o Sample Number (specific to sampling event i.e. location)
o Type of sample, i.e., graJb, 24 hour composite, etc.
o Date, Time (24 hour time is preferable, i.e. , 1600 vs.
4:00 p.m.)
o Sample Location
o Preservatives
o Analytical Parameter(s)
o Collector
o Special Conditions or Remarks.
Labels and ink should be waterproof. Fix labels to con-
tainers with clear waterproof tape. Tape completely around
container and over label to prevent accidental label loss or ink
smear during shipping and handling.
2.7.2 Chain-of-Custody
Each sample shipment requires a chain-of-custody record. A
chain-of-custody document provides a record of sample transfer
from person to person. This document helps protect the integrity
of the sample by ensuring that only authorized persons have
custody of the sample. In addition, the chain-of-custody
procedure ensures an enforceable record of sample transfer which
is necessary if the sample results are to be used in a judicial
proceeding alleging violations of sludge standards. This
document shall record each sample's collection and •handling
history from time of collection until analysis as well as the
information listed on each sample bottle. All personnel handling
the sample shall sign, date and note the time of day on the
chain-of-custody document. A sample chain-of-custody document is
provided in Appendix A.
2-26
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2.7.3 Sampling Log Book
All sampling activities should also be documented in a bound
log book. This book duplicates all information recommended for
the chain-of-custody document above, and notes all relevant
observations regarding sample stream conditions.
2.8 SAFETY CONSIDERATIONS
Safety is important in sludge sampling, especially since
many sampling points preclude direct collection of grab samples.
Several safety considerations are noteworthy given the potential
health-related effects of sewage and sludge, and the hazards
associated with treatment plant equipment (water, electricity,
moving components, etc.).
Personal hygiene is important for all personnel involved in
sludge sampling efforts. Sludge presents a unique health hazard,
not only because of the potential presence of toxic substances,
but also because of the abundance of pathogens (bacteria, viruses
and worms). As a precautionary measure, inoculations are
recommended for all personnel who have direct contact with sludge
(as well as any wastewater) samples. As a minimum, inoculation
should include diseases such as typhoid and tetanus. Avoidance
of direct sludge contact is preferred and is possible if proper
precautions are taken. Wear rubber or latex gloves at all times,
especially while collecting or handling samples, and use
waterproof garments when the risk of splashing exists. Wash any
cuts or scrapes thoroughly and treat immediately.
Gas production from biologically active sludge samples may
cause pressure build up, especially if the samples are not stored
at 4°C as recommended in Table 2.3. Treating samples with the
appropriate preservatives (e.g., acids for metals samples) as
2-27
-------
well as refrigeration will significantly suppress biological
activity and. therefore gas evolution. However, except for
volatile and semi-volatile analysis samples, pressure may need to
be periodically released to prevent explosions of the sealed
sampling containers. The field control sample should also be
vented to expose it to the same potential contaminants.
There are several universal safety precautions that are
applicable to sludge sampling as well. When sampling sludge in
confined areas, particularly around anaerobic digesters,
dangerous gases may be present. These gases may include either
explosive vapors (methane), poisonous mixtures (including
hydrogen sulfide), or oxygen-deprived atmospheres (carbon
dioxide). Explosive vapors require care to avoid sparks and
possible ignition. These situations necessitate adequately
ventilated equipment, gas detection meters and backup breathing
apparatus. Exercise care around open pits or uncovered holes.
Proper lighting increases the visibility of such hazards. Loose
or dangling garments (ties, scarves, etc.) should not be worn
around equipment with moving parts, especially pumps. Exercise
extra awareness around pumps controlled by intermittent timers.
Finally, be very careful when sampling high pressure sludge lines
or lines containing high temperature, thermally-conditioned
sludges (i.e., Zimpro or Porteus) in order to avoid injury by
either high pressure streams or burns.
2-28
-------
3. ANALYTICAL PROCEDURES
Sewage sludge is compositionaiiy diverse, rich in organic
matter! and highly variable in physical and chemical properties,
Sewage sludge analysis is difficult because of the inherent
complexity of sludge matrices. Matrix complexity often results
in significant analytical interference which can lead to poor
analytical accuracy and precision with a resultant loss of data
reliability. For example, matrix interference, which is
exacerbated in sludges, can both mask the identity of analytes by
suppressing instrumental response, or falsely contribute to a
positive response.
Variations in the physical and chemical properties of sewage
sludge often maJce it difficult to obtain samples which represent
the material as a whole. The diversity of sludge
characteristics, coupled with the heterogeneous nature of
sludges, presents a considerable challenge to precise and
accurate determinations of trace levels of pollutants in sludges.
Often sludge samples must be diluted to attain analytical
results. A tenfold sample dilution means a tenfold increase in
the detection limit (e.g., 1 ppm to 10 ppm). This increases the
complexity of attaining accurate, precise data.
The following sections provide a summary of the analytical
techniques available for characterization of the sewage sludge
and soil constituents considered important in the selection of
use or disposal options. Analytical techniques for conventional
pollutants, inorganics, priority pollutant metals, priority
pollutant organics, and pathogenic organisms are discussed.
3-1
-------
3.1 CONVENTIONAL AND INORGANIC POLLUTANT PARAMETERS
Conventional pollutant parameters have historically been the
focal point of sewage sludge analyses. The parameters normally
associated with this group include total suspended solids, pH,
oil and grease, BOD and fecal coliform. Inorganics, which have
also been of concern, include phosphorus species, nitrogen
species, phenolics, and total cyanide. As Table 3.1 indicates,
the analytical protocols commonly employed for these analyses are
adaptations of gravimetric or colorimetric techniques developed
for aqueous samples.
Existing federal regulations (40 CFR Part 257) require PCTWs
that apply sludge to food-chain croplands to measure the pK of
the sludge-soil mixture and background soil cation exchange
capacity (CEO. Soil pH should be measured using a 1:1 solution
of sludge-soil mixture and deionized water (see Table 3.1). For
distinctly acid soils, CEC should be measured using the summation
method (see Table 3.1). For neutral, saline, or calcareous
soils, the sodium acetate method should be used (see Table 3.1).
Another inorganic of more recent concern is asbestos.
Asbestos is a generic term which refers to naturally occurring,
commercially useful fibrous silicate mineral. There are two
types. Chrysotile, which comprises 93 percent of the current
asbestos production, is a hydrated magnesium silicate which
exhibits a much higher cancer risk for textile workers.
Amphibole, which occurs in five forms, crccidolite, amosite,
actinolite, tremolite and anthrophyllite, is a hydrated silica
associated with various lung carcinogenic trace metals (nickel,
chromium, aluminum and iron). Crocidolite poses the greatest
health risk of all asbestos types and is the riskiest to miners
and millers.
3-2
-------
TABLE 3 . 1
ANALYTICAL TECHNIQUES FOR CONVENTIONAL AND INORGANIC POLLUTANTS IN SLUDGE
Parameter
Phos-
phorous
(Ortho &
Total)
Total
Kjeldahl
Nitrogen
Ammonia
Nitrate
Nitrate-
Nitrite
Nitrite
Analytical
Preparation Technique
Techniques (a)
Acidic Digestion C
Turbid samples
must be filtered
after digestion
H2S04 digestion C
Colorimetric C
reaction ISE
Reaction to C
brucine sulfate or
Nitrate-nitrite N
minus Nitrite N
Hydrazine or C
Cd reduction
Diazot i zation S
Aqueous
QA/QC Detection
(b) Limit (mg/1) Comments
B 0.001 - High iron concentration
St can cause precipitation
Sp and loss of phosphorous
- Turbidity interference
- 24 hr-holdina time
- Digestion solution 2
B 0.05 times for sludge
St - 24 hr-holding time
- Fe t Cr catalyze; Cu
inhibits reaction
Sp 0.05 - Hg can complex with NH4
- Filter sample
- Distillation required
prior to analysis
0.1 - Dissolved organic
matter
Method
(1)
(1)
351
(1)
350
(2)
B. D
(1)
(3)
0.05 - Filter sample for Cd (1)
1 - Strong oxidizing or
or reducing agents
- Suspended matter in
reduction column
- Samples which contain high
cone, of metals or orcranics
0.5
(1)
(2)
365. 3
.2, 3
350. 1
.2, 3
417A,
. E. G
352. 1
9200
353.1,
353.2
354. 1
419
-------
TABLE 3.1 (Continued)
ANALYTICAL TECHNIQUES FOR CONVENTIONAL AND INORGANIC POLLUTANTS IN SLUDGE.
Analytical Aqueous
Preparation Technique QA/QC Detection
Parameter Techniques (a) (b) Limit (mg/1)
Comments
Method
Cyanide
Phenolics
Total
Organic
Carbon
Chemical
Oxygen
Demand
Bio-
chemical
Oxygen Pen
Oil and
Grease
PH
CEC
CN converted to C
HCN by reflux-
distillation
Distillation and C
extraction
Inorganic Catalytic
carbon combustion &
removal dispersive IR
Oxidation to Titration
potassium dichro-
mate and HCl
Incubation Measurement
of reduction
iiand in DO
Solvent G
extraction
Solution in ISE
suspension with
fluid
BaCiy treatment T
(acid exchange) C
(base exchange)
B 0.02
St.
So
B 0.002
St
SP
B 1.0
St
Sp
B 5.0
St
Spi
B 2.0
St
Sp
B 5.0
Sp
St
None cited in
references
- Fatty acids and
sulfides interfere
- 24 hr-holding time
- Sulphur compounds and
oxidizing agents
interfere
- Carbonate + bicarbonate
interfere
- Possible loss of
volatiles
- Chloride oxidation
could be an
interference
- 5-day incubator
- Interference from solids
and oily residues
- Acid soils
(1) 335.2
(3) 9010,
or 9012
(1) 420.1
(2) 510A
or C
(3) 9065,
9066. 9067
( 1 ) 415.1
(2) 505A
(3) 9060
(1) 410.1,
(Block
digestion)
(2) 1508 A
or B
(1) 405.1
(2) 507
(1) 413. 1 ,2
(2) 503A, D
(3) 9070,
or 9071
(1) 150.1
(3) 9040
(4) p. 900,
57-4
(3) 9080
(4) Ibid.
-------
TABLE 3.1 (Continued)
ANALYTICAL TECHNIQUES FOR CONVENTIONAL AND INORGANIC POLLUTANTS IN SLUDGE
Parameter
CEC
Preparation
Techniques
Na acetate
sludge sol 'n,
isopropanol
wash , NH.
Analytical Aqueous
Technique QA/QC Detection
(a) (b) Limit (ing/1)
Emission One B No data
or per available
absorption batch
AAS
Comments Method
- Neutral, saline, or (3)
calcareous soils (4)
9081
p. 891
acetate exchange
Solids
% Solids
Filtration
Evaporation
Gravimetric B 4.0-10.0
Gravimetric B N/A
(1)
or
(1)
(2)
160.1
.5
160. 3
209A
(U Me_tjipds_j-'pr Chemical Analysis of Water and Hastes, EPA-600/4-79-020, March 1983.
(2) Standard Methods for the Examination of Water and Wastewater. 16th Edition, Mary Ann
Franson, managing ed., American Public Health Association, Washington, DC, 1985.
(3) Test Methods for Evaluating Solid Waste, Third Edition, (SW-846), EPA, September
1986.
(4) "Methods of Soil Analysis", Agronomy Monograph Number 9, C.A. Black, ed. , American
Society of Agronomy, Madison, Wisconsin, 1965.
(a) C Colorimetric; DO - Dissolved Oxygen; G - Gravimetric; IR - Infrared; ISE - ion
Selective Electrode; S - Spectropnotometric; T - Titration
(b) B - Blanlc(s); St. - Standards; Sp - Spike(s)
-------
In certain cases, such as when large scale asbestos removal
is/will occur during the permit term or in municipalities where
asbestos industries are located, the permit writer or the
permittee may feel that sampling the sewage sludge for asbestos
is warranted. Consult Table 2.4 for the appropriate sample
sizes, containers, preservatives and holding times. Unless
sample preparation will be within 48 hours, the sample should be
refrigerated or stored in the dark to prevent bacterial growth.
Although there are tests which differentiate between the
various asbestos types, current research does not associate
health risk with specific types. The risk from asbestos is
directly proportional to the concentration of airborne respirable
particles. Thus current recommended analytical detection methods
count fibers per area. Respirable particles are those with a
diameter (length in this case) of less than 2 microns, which can
only be detected using transmission electron microscopy (TEM).
The polarized light microscopy (PLM) method does not detect
respirable particles.
3.2 METALS
There are several analytical techniques used for the
determination of metals in sewage sludge, with variations in both
the sample preparation and analysis steps. A discussion cf these
techniques follows.
3.2.1 Analyte Isolation/Preparation Overview
Two approaches are currently used to evaluate the
concentrations of metal contaminants ir. sludges. The most
frequently used approach involves determination of the total
metal content or other materials of interest, without regard to
chemical form. The analytical techniques for such determinations
3-6
-------
are designed to solubilize all of the metal species (bound to
organic particulates and mineralogically bound). In the other
approach, often referred to as the "leachate approach," the
proportion of the total contaminant loading which will become
available or mobilized under environmental conditions is
determined. Thus, leachate techniques are designed to mimic a
given environmental scenario. With either approach, the
complexity and variability of sludge matrices has made the
development of sample preparation techniques a great analytical
challenge.
The two primary steps for sample preparation of merals in
sewage sludge are (1) dissolution of the sample portion
containing the metal components of interest, and (2) elimination
of inorganic and organic interferences. The preparation
procedure must be capable of effectively liberating the analytes
from, the solid constituents, solubilizing the elemental species,
homogenizing the sample phase(s) of interest, as well as
completely oxidizing the associated organics. Sludge matrices
are challenging in this regard because of the high organic levels
and solids leadings characteristics.
All state-of-the-art sample preparation procedures for total
metal determinations depend on acid-mediated digestions and
chemical or physical oxidation techniques. The approach involves
the use of strong acid and elevated temperature digestion
procedures in combination with chemical or physical oxidants.
The modifications which have been used include variations in
acids, oxidation reagents, physical oxidation techniques,
reaction conditions, and/or the sequence in which components are
employed. Acids used most frequently include nitric acid (HN03) ,
hydrofluoric acid (HF), hydrochloric acid (KCL), and perchloric
acid (HCL04); while hydrogen peroxide and perchloric acid are
3-7
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common oxidizing reagents. High temperature (550°OC) combustion
and low temperature plasma ashing (LTPA) have been used success-
fully as physical oxidants. Closed system digestion procedures
are also used successfully.
Two closely related techniques to estimate the amount of
inorganic and organic contaminants which may be leached from the
sludge after disposal in landfills or surface impoundments are
the Extraction Procedure protocol and the Toxicity Characteristic
Leachate Procedure. In both procedures the sludge is maintained
in an aqueous slurry under a given set of conditions, after which
contaminant levels are measured on the filtered aqueous media.
The Extraction Procedure (EP) test developed by EPA (in response
to RCRA legislation) to evaluate the impact of landfill waste
disposal practices on subsurface and surface waters (40 CFR Part
261 Appendix II) evaluates criteria for 8 metals and 6
pesticides. The proposed Toxicity Characteristic Leaching
Procedure {TCLP) 51 Federal Register 21648 is expected to be
promulgated in August/September of 1989. The TCLP test which
evaluates the same 8 metals and 6 pesticides and an additional 38
compounds will replace the EP test after promulgation.
3.2.2 Analytical Techniques for Metals
3.2.2.1 Sample Preparation/Digestion
Table 3.2 shows the sample preparation/digestion technique
recommended by the USEPA. Method 3050 (SW-846, 3rd ed.) is an
acid digestion procedure used to prepare sediments, sludges, and
soil samples for analysis by flame or furnace atomic absorption
spectroscopy (FLAA and GFAA, respectively) or by inductively
coupled argon plasma spectroscopy (ICAP). Samples prepared by
this method may be analyzed by ICAP for all the metals listed
below, or by FLAA or GFAA as indicated:
3-8
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FLAA
GFAA
Aluminum
Antimony
Barium
Beryllium
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Potassium
Silver
Sodium
Thallium
Tin
Vanadium
Zinc
Arsenic
Beryllium
Cadmium
Chromium
Cobalt
Copper
Iron
Lead
Manganese
Nickel
Selenium
Silver
Zinc
Thallium
Vanadium
Method 3050 prepares samples for analysis of total metals
(except mercury, silver and antimony) determination through
vigorous digestion in nitric acid and hydrogen peroxide followed
by dilution with either nitric or hydrochloric acid. This method
is not appropriate for mercury, silver, and antimony because of
potential for volatilization. For the digestion and analysis
procedures for mercury, silver and antimony, see section 3.2.2.2.
3.2.2.2 Ana-lytical Detection Methods
Metals should be analyzed using either Atomic Absorption
Spectrometry (AAS) or Inductively Coupled Argon Plasma (ICAP).
The following discussion generally describes both methods.
Inductively Coupled Argon Plasma is a form of.optical
emission spectroscopy which uses an argon plasma to excite ions
and atoms. This process causes the ions and atoms to emit light
which is measured as a signal. The signal response is
proportional to concentration level, and each element emits a
uniquely characteristic light. This technique poses several
advantages. A linear relationship between concentration and
signal response can be expected over 4-6 orders of magnitude.
Detection limits are low (although not as low as AAS, and not
strongly inhibited by matrix variation); costs are moderate since
3-9
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TABLE 3.2.
RECOMMENDED PREPARATION TECHNIQUE
FOR ELEMENTAL ANALYSIS OF SLUDGE SAMPLES
METHOD 3050(1!
1) Mix the sample thoroughly to achieve homogeneity. For each
digestion procedure, weigh to the nearest 0.01 g and
transfer to a conical beaker a 1.00- to 2.00-g portion of
sample.
2) Add 10 ml of 1:1 HN03, mix the slurry, and cover with a
watch glass. Heat the sample to 95°C and reflux for 10 to
15 min without boiling. Allow the sample to cool, add 5 ml
of concentrated HNOj, replace the watch glass, and reflux
for 30 min. Repeat this last step to ensure complete
oxidation. Using a ribbed watch glass, allow the solution
to evaporate to 5 ml without boiling, while maintaining a
layer of solution over the bottom of the beaker.
3) After Step 2 has been completed and the sample has cooled,
add 2 mi of Type II water and 3 ml of 30% H202. Cover the
beaker with a watch glass and return the covered beaker to
the hot plate for warming and to start the peroxide
reaction. Care must be taken to ensure that losses co not
occur due to excessively vigorous effervescence. Heat unti:
effervescence subsides and cool the beaker.
4) Continue to add 30% H202 in 1-ml aliquots while warming
until the effervescence is minimal or until the general
sample appearance is unchanged.
NOTE: Do not add more than a total of 10 ml 30% H-0-.
(1) USEPA "TEST METHODS FOR EVALUATING SOLID WASTE: VOLUME 1A"
SW-846 3rd EDITION, NOVEMBER 1986. CHAPTER 3, PP. 3050-1,5
3-10
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many elements may be determined at once; and analysis time is
fairly rapid. The primary drawbacks are: matrix interferences
(as with all analyses); the fact that solid samples cannot be
analyzed directly as in AAS; and the high cost of purchasing ICAP
instruments (more than $100,000).
The basic principle behind atomic absorption spectroscopy is
the opposite of the emission method, ICAP. In AAS, the analyte
(metal) is dissociated into atoms in a flame or furnace, and
passed through a light beam from the reference source. This
reference source emits a beam of the characteristic atomic
spectrum of the analyte. The anaiyte in the sample will absorb
this energy thus decreasing the original signal to the detector
from the reference beam. Since absorption is directly
proportional to concentration, the analyte concentration can be
determined. Selection of a specific wavelength which corresponds
to one of the more intense characteristic line of the analyte's
spectra allows for high element specificity. For this reason,
AAS is more responsive than ICAP to lower concentrations of
metals in sludge. However, this very precise nature of AAS is
also the cause of its major drawback: only one elemental
determination per sample is possible at a time. Thus, the total
analysis time of AAS is significantly greater tihan thar of ICA?
when many metals are present in the sample.
In sewage sludge applications, it is important to realize
that both of these analytical techniques are reliable tools and
neither offers a significant technical advantage over the other.
However, ICAP's capability to simultaneously analyze multiple
elements is a tremendous advantage in terms of sample throughput
and labor savings, which may outweigh the noted limitations." For
sludge applications, EPA recommends either method and leaves the
3-11
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final decision to individual POTWs. Table 3.3 summarizes the
relative advantages and disadvantages of ICAP and AAS.
TABLE 3.3
COMPARISON SUMMARY OF ICAP AND AAS
ICAPAAS
Cost for Instrument
Cost per Sample
Detection Limits
Precision
Linear Working Range
Sensitivity
Number of Elements/Sample
Analysis Time
Spectral Interference
Matrix Interference
disadvantage
+ advantage
+ extra advantage
ICAP Method 6010
EPA recommends Method 5010 for the determination of metals
in solution by Inductively Coupled Argon Plasma atomic emission
spectroscopy (ICAP). This method can be found in the USEPA
manual "Test Methods for Evaluating Solid waste," (SW-346, :-:cv.
1986, 3rd Ed., Vol 1A, pp. 6010-1,17). The method is applicable
to a large number of metals and wastes. All matrices, including
ground water, aqueous samples, E? extracts, industrial wastes,
soils, sludges, sediments, and other solid.wastes, require
digestion prior to analysis. EPA recommends digestion Method
3050 (SW-846, 3rd Ed. - see Section 3.2.2.1).
3-12
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Elements for which Method 6010 is applicable are listed in
Table 3.4. Detection limits, sensitivity, and optimum ranges of
the metals win vary with the matrices and model of spectrometer.
The data shown in Table 3.4 provide concentration ranges for
clean (interference-free) aqueous samples. Due to matrix
interferences, the detection limits in typical sludge samples
will be somewhat higher. Use of this method is restricted to
spectroscopists who are knowledgeable in the correction of
spectral, chemical, and physical interferences.
Atomic Absorption Methods
EPA recommends use of the methods listed in the manual "Test
Methods for Evaluating Solid Waste" (SW-846, Nov. 1935, 3rd Ed.,
Vol 1A) for the determination of metals in solution by atomic
absorption spectroscopy. A complete set of procedures for each
metal-specific method may be found on pages 7000-1 to 7950-3.
These methods are simple, rapid, and applicable to a large number
of metals in drinking, surface, and saline waters as well as
domestic and industrial wastes. Ground water, aqueous samples
other than drinking water, E? extracts, industrial wastes, soils,
sludges, sediments, and other wastes require digestion orior to
analysis. EPA recommends digestion Method 3050 (SW-846, 3rd Ed.
- see section 3.2.2.1).
Detection limits, sensitivity, and optimum ranges of the
metals will vary with the matrices and models of atomic
absorption spectrometers. The data shown in Table 3.5 provide
some indication of the detection limits obtainable by direct
aspiration and by furnace techniques. Due to the matrix
For drinking water and other non-sludge applications, priority
pollutant scans may require very low contaminant detection
levels. Therefore, there may be no choice except to rely en the
lower detection limit capability of graphite furnace AAS. This,
in turn, will determine'the digestion method used.
3-13
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TABLE 3.4
RECOMMENDED INDUCTIVELY COUPLED WAVELENGTHS
AND ESTIMATED INSTRUMENTAL DETECTION LIMITS
Element
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Chromium
Cobalr
Copper
Iron
Lead
Magnesium
Manganese
Molybdenum
Nickel
Potassium
Wastewater EMSL ' s Best EMSL's
Wavelength9 Estimated SLUDGE Estimate of
(nm) Detection Detection Routine
Limitb Limit0 SLUDGE Limit
(ug/L) (ug/L) (ug/L)
308.
206 .
193.
455.
313.
249.
225.
317.
267.
228.
324.
259.
220.
279.
257.
202.
231.
766 .
215
833
696
403
042
773
502
933
716
616
754
940
353
079
610
030
604
491
45
32
53
2
0.3
C __
4 1
10
7 --
7 —
6 5
7
42 20
30
2
8 10
15
See note d --
—
--
—
—
—
—
5
--
--
—
10
--
50
--
--
30
—
-------
TABLE 3 . 4
[cont.)
RECOMMENDED INDUCTIVELY COUPLED WAVELENGTHS
AND ESTIMATED INSTRUMENTAL DETECTION LIMITS
Element
Wavelength
(run)
Wastewater
Estimated
Detection
Limitb
(ug/L)
EMSL'S Best
SLUDGE
Detection
Limit0
(ug/L)
EMSL's
Estimate of
Routine
SLUDGE Limit
(ug/L>
Selenium
Silicon
Silver
Sodium
Thallium
Vanadium
Zinc
196.
288.
328.
588.
190.
292.
213,
026
158
068
995
864
402
856
75 75
58
7
29
40 100
8
2 5
100
—
—
—
150
--
15
Reference: Test Methods for Evaluating Solid Waste: SW-846.
a The wavelengths listed are recommended because of their
sensitivity and overall acceptance. Other wavelengths may be
substituted if they can provide the needed sensitivity and are
treated with the same corrective techniques for spectral
interference. In time, other elements may be added as more
information becomes available and as required.
b The estimated instrumental detection limits are shown. They are
given as a guide for an instrumental limit. The actual method
detection limits are sample dependent and may vary as the sample
matrix varies.
c EPA's Environmental Monitoring Support Laboratory detection
limit ranges.
Highly dependent on operating conditions and plasma position.
-------
TABLE 3.5
ATOMIC ABSORPTION FLAME AND FURNACE INSTRUMENTAL DETECTION
AND SENSITIVITY LIMITS FOR WASTEWATER SAMPLES
Direct Aspiration
Metal
Detection Limit
(mg/L)
Sensitivity
(mg/L)
Furnace Procedure'
Detection Limit
(ug/L)
Aluminum
Antimony
Arsenic
Barium(p)
Beryllium
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury2
Molybdenum(p)
Nickel (p)
Potassium
Selenium3
Silver
Sodium
Thallium
Tin
Vanadium ( p)
Zinc
0.1
0.2
0.002
0.1
0.005
0.005
0.01
0.05
0.05
0.02
0.03
0.1
0.001
0.01
0.0002
0.1
0.04
0.01
0.002
0.01
0.002
0. 1
0- 2
1
0.5
0.4
0.025
0.025
0.08
0.25
0.2
0.1
0.12
0.5
0.007
0.05
—
0.4
0. 15
0.04
--
0.06
0.015
0.5
0.8
0.8
0.005
3
1
—
0. 2
0. 1
—
1
1
—
—
1
—
—
—
1
—
—
2
--
--
i_
4 —
4
0.02--
Reference: Test Methods for Evaluating Solid Waste: S/J-846.
NOTE: The symbol (p) indicates the use of pyrolytic graphite
with the furnace procedure.
a For furnace sensitivity values, consult instrument operating
manual.
b Gaseous hydride method.
c The listed furnace values are those expected when using a
20-uL injection and normal gas flow, excepr in the cases of
arsenic and selenium, where gas interrupt, is used.
d Cold vapor technique.
-------
interferences, the detection limits for typical sludge samples
will be somewhat higher.
Mercury Analysis
The physical-chemical characteristics of mercury are not
amenable to digestion by the generally recommended technique,
Method 3050. For the determination of total mercury (organic and
inorganic) in soils, sediments, bottom deposits, and sludge
material, EPA recommends using Method 7471, a cold-vapor atomic
absorption spectrcmetry. This method appears in the EPA manual
"Test Methods for Evaluating Solid Waste." (SW-846, Nov. 1986,
3rd Ed., pp. 7471-1,10). Prior to analysis, the solid or
semi-solid samples must be prepared according to the procedures
discussed in this method. The typical detection limit for this
method is 0.0002 mg/L.
Antimony and Silver Analysis
The procedures for preparation of antimony and silver
samples are given in Method 3005. Method 3005, a soft digestion,
is presently the only digestion procedure recommended for
antimony. It yields better recoveries than either Method 3010 or
3050. There is no hard digestion for antimony at this time
(SW-846, Nov. 1986, 3rd Ed., p. 7041-2). Samples prepared by
Method 3005 are amenable to determination by either ICAP Method
6010 or the atomic absorption furnace technique, Method 7041.
{SW-846, 3rd Ed. - see pp 7041-1 through 7041-4). Detection
limits for Method 7041 are 3 ug/L for antimony and 10 mg/1 for
silver.
3-17
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3 . 3 ORGANICS
The evolution of analytical techniques for organic
contaminants has involved a number of modifications to a basic
method in order to widen potential applications. Because the
instrumentation is complex and the number of possible analytes is
large, quality control is difficult to monitor and several
analytical techniques are required. As with analyses for metals
and other elements, the organic-rich complex matrices character-
istic of sewage sludges often mean that analyte
extraction/isolation procedures play a significant role in -he
reliability of the resultant analytical data.
3.3.1 Overview of Analyte Extraction and Isolation
For a number of reasons, EPA has focused regulatory
attention on two categories of contaminants: volatile organics
and semi-volatile organics. While the classification of these
groups is founded upon inherent physical/chemical properties,
extraction and isolation techniques are the functional basis for
the distinction.
Volatile Oraanics
Two methods are available for extraction and isolation of
volatile organics in aqueous and solid matrices: aeadspace
techniques and purge and trap techniques. Several versions of
these procedures have been sanctioned by regulatory agencies
and/or developed for use in specific applications. For POTW
sludge sampling and analysis, EPA recommends two analytical
methods (1624C, 624-S) which both extract via purge and trap (see
Section 3.3.2) .
3-18
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Purge and trap requires moderate sample preparation. The
method relies upon a stripping process in which an inert gas is
bubbled through the sample to remove the volatile organics. The
volatilized organics are transferred from the aqueous/solid phase
to the gaseous phase and subsequently trapped on a solid
adsorbent column. The adsorbent column is then heated and the
trapped organics are thermally desorbed and swept into the
analytical instrument.
Semi-volatile Organics
The first step in all procedures for determination of semi-
volatile organics is solvent extraction. (Note: For extraction
procedures recommended by EPA for sludge analysis see Section
3.3.2). The sample material is mixed and agitated with a
solvent, causing the organic analytes to be preferentially
partitioned into the solvent phase. Extractions are typically
performed at both acidic and basic pH ranges to facilitate
extraction of ionizable organics. Modifications to the
extraction method are usually based upon the manner in which the
sample-solvent mixture is agitated and post-extraction cleanup
procedures.
The organic solvent used most frequently for extraction of
semi-volatile analytes is methylene chloride, either singly or in
combination with a more polar solvent. Extraction techniques
which are applicable to sludge and solid matrices include:
o Sonication extraction
o Continuous liquid-liquid extractors
o Soxhlet extraction
o Mechanical agitation (shaJcer table, homogenization, or
wrist-action shaJcer) .
3-19
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Sonication relies on the mechanical energy developed from
ultra-sonic devices to affect agitation and solvent-solid
contact. The best approach involves the use of a sonication horn
which is immersed into the solvent-sample mixture, rather than a
sonication bath. This technique has also been proven effective
in sludge and sediment applications.
Continuous liquid-liquid extractors and Soxhlet extractors
employ the same basic principle of operation. The extraction
solvent is distilled from a reservoir, condensed above the sample
material, and subsequently rains down through the sample. The
distillation-condensation process continues until a volume of
solvent has collected sufficient force to establish a siphon, at
which point the extraction solvent is siphoned back into the
reservoir. The cycle is repeated with freshly distilled solvent
and is generally allowed to occur for 12-24 hours. The
continuous liquid-liquid extraction procedure can only be used on
low solids «5%) sludges, while the Soxhlet technique is most
useful for materials with low water content.
A variety of mechanical agitation techniques have been used
for extractable organics determinations, including hcmogen-
ization, wrist-action shakers and platform shakers (shaker
tables). The objective of each technique is to maximize the
contact between the extraction solvent and. the solid particles.
Wrist-action and platform shakers have both proven adequate, with
wrist-action shakers generally preferable for smaller sample
containers and platform shakers preferable for larger extraction
vessels. Homogenization relies on agitation of the solvent-solid
mixture, rather than agitation of the entire extraction vessel.
This technique has been used quite successfully in sludge
applications as a result of its superior agitation. However ,
3-20
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sand, a fairly common constituent of sewage sludge, literally
chews up high speed homogenizers.
As a result of the complexity of sludge matrices ,
fractionation and/or cleanup procedures are often required after
sample extraction to minimize interference. The basic concept
used in virtually all cleanup techniques is selective adsorption
of the interfering components. Although a variety of cleanup
procedures have been developed for specific analytes, the
techniques commonly employed for the listed applications include:
o Gel permeation resins - broad spectrum cleanup and
higher molecular weight biogenic organics
o Activated carbon - fractionation and general purpose
cleanup
o Alumina adsorbent - inorganic adsorbent
o Florisil adsorbent - inorganic adsorbent
o Silica gel adsorbent - inorganic adsorbent
o Copper and mercury - removal of sulfur-containing
compounds.
Cleanup procedures can be used individually or in combination
with.other procedures, depending upon the need of the particular
application and the complexity of the sample.
For more detail regarding extraction and isolation
techniques, consult the references cited in 40 CFR Part 136,
"Guidelines for Establishing Test Procedures for the Analysis of
Pollutants."
3-21
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3.3.2 Recommended Analytical..Techniques for Organics
For determining concentrations of organic pollutants in
sludge, EPA recommends two methods designed for qualitative and
quantitative analysis of municipal and industrial wastewater
treatment sludges:
o Volatile Organics - 624-S (EPA 1984b) or 1624C (EPA
1988a)
o Semi-Volatile Organics - 625-S (EPA 1984b) or 1625C (EPA
1988a)
Each of these two methods employ gas chromatography/mass
spectrometry (GC/MS).
GC/MS is a combination of two microanalytical techniques:
gas chromatography (a separation technique) and mass spectrometry
(an identification technique). A sample aliquot is prepared for
extraction, extracted, then introduced to the GC/MS system. The
extract is vaporized quickly at an elevated temperature ana
carried by an inert gas (mobile phase) through a coatsd column
(stationary phase). Separation of the extract components is
effected by their differential partitioning between stationary
and mobile phases. The separated components exit the column and
enter the mass spectrometer (MS) where they are decomposed to
specific unimolecular species. The manner in which a component
fragments is characteristic of that component and is the basis
for identification. The MS detector quantifies a compound by
responding with a signal proportional to the detected amount of
the compound.
The GC/MS system is calibrated by measuring sigral response
to three to five analyte standard solutions of various
concentrations (e.g., 20-160 ng/ml). The solutions are carefully
3-22
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prepared mixtures of pollutants suspected to be present in the
sample, as well as a few labeled pollutant analogs known as
internal standards. The accumulated measurements form an
instrument response curve. Samples are spiked with the same
internal standards at a fixed concentration immediately prior to
analysis. If the MS detects any sample-originated pollutants,
the generated signal for each pollutant is measured against both
the internal standard and the response curve.
GC/MS analysis affords several advantages over other
techniques:
o Provides qualitative and quantitative information about
a wide range of organic compounds.
o Confirms specific information from a small sample size.
o Produces a spectrum with a fragmentation pattern, or
fingerprint, which can be used to identify an unknown.
3.3.2.1 Methods 1624C and 1625C
Methods 1624C and 1625C are draft methods for analyzing
volatile organics (Method 1624C) and base/neutral, non and semi-
volatile organics (Method 1625C) in sludge. These methods were
developed by the USEPA Office of Water Industrial Technology
Division, and are derived from previous methods 1624 and 1625
(see 40 CFR Part 136) for analyzing wastewaters.
The 1624C/1525C (and 1624/1625) test procedures are isotope
dilution techniques. In conventional GC/MS, up to six internal
standards are used to quantify the response of perhaps several
dozen analytes. Isotope dilution GC/MS employs stable,
isotopically labeled analogs of the compounds of interest, which
is analogous to providing a separate internal standard for each
analyte. The result is that isotope dilution GC/MS is sensitive
3-23
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to even minute contaminant concentrations. Methods 1624C/1625C
and 1624/1625 are similar in this respect but differ in sample
preparation.
Method 1624C sample preparation for sludge samples consists
of the following three routes, depending on the percent (%)
solids content of the sludge. If the solids content is less than
one percent, stable isotopically labeled analogs of the compounds
of interest are added to a 5 gram sample and the sample is purged
in a chamber designed for soil or water samples. If the solids
content is 30 percent or less, the sample is diluted to one
percent solids with reagent water, and labeled compounds are
added to a 5 gram aliquot of the sludge/water mixture. The
mixture is then purged. If the solids content is greater than 30
percent, five ml of reagent water and the labeled compounds are
added to a 5 gram aliquot of sample. The mixture is then purged.
Method 1625c sample preparation for sludge.samples consists
of the following three routes, depending on. the percent (%)
solids content of the sludge. If the solid's content is less than
one percent, a one liter sample is extracted with methylene
chloride using continuous extraction techniques. If the solids
content is 30 percent or less, the sample is diluted to one
percent solids with reagent water, homogenized ultrasonically,
and extracted. If the solids content is greater than 30 percent,
the sample is extracted using ultrasonic techniques. Each
extract is subjected to a gel permeation chromatography (GPC)
cleanup.
These methods are currently undergoing revision at EPA's
Environmental Monitoring and Support Laboratory for problems
relating to the sample preparation portions. They are the
3-24
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methods used in the National Sewage Sludge Survey (which EPA is
conducting to provide a current data base to be used to set
pollutant limits, evaluate risks of use and disposal practices,
and evaluate the impacts of the proposed rule) and also are
discussed in the 40 CFR Part 503 regulation proposed on February
6, 1989 and now out for comment. Depending on the results of the
comment period, the isotope dilution methods may be exclusively
required for priority pollutant organics analysis when 40 CFR
Part 503 is finalized.
3.3.2.2 Methods 624-S and 625-S
Methods 624-S and 625-S are existing methods for the
measurement of organic priority pollutants in sludges. These
test procedures were derived from previously developed methods
624 and 625 for analyzing wastewaters (see 40 CFR Part 136). The
624-S/625-S techniques are conventional GC/MS and operate as
described in Section 3.3.2. Method 624-S is used to analyze for
volatile organic compounds. Method 625-S is used for
semi-volatile or nonvolatile organics.
In Method 624-S, an inert gas is bubbled through a 10-ml
sludge aliquot contained in a purging chamber at ambient
temperature. The purgeable compounds are transferred from the
aqueous phase to the vapor phase. The vapor is carried through a
sorbent column where the purgeables are trapped. After purging
is completed, the sorbent column is heated and backflushed with
the inert gas to desorb the purgeables into a gas chromatographic
column. The gas chromatograph is temperature programmed to
separate the purgeables which are then detected with a mass
spectrometer.
Method 625-S uses repetitive solvent extraction (see section
3.3.1) aided by a high-speed homogenizer. The extract is
3-25
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separated by centrifugation and removed with a pipette or
syringe. Extracts containing base/neutral compounds are cleaned
by silica gel or florisil chromatography or by gel permeation
chromatography (GPC). Extracts containing the acidic compounds
are cleaned by GPC. The organic priority pollutants are
determined in the cleaned extracts by capillary column or packed
column GC/MS. Option A, i.e., extract cleanup by silica gel cr
florisil chromatography and analysis by capillary column GC/MS
(HRGC/MS) is preferred since HRGC/MS allows easier data
interpretat i on.
While Methods 1624C/1625C provide lower detection limits, in
some cases, than Methods 624-S/625-S, these methods are also more
costly. Presently, Methods 1624C/1625C cost about $2,200-S2 , 400
per sample, which is approximately $200-$400 more than a similar
analysis by Methods 624-S/625-S. The extra cost reflects the
Method 1634/1635 isotope spikes and approximately two weeks of
work necessary to prepare additional spectral Libraries.
Neither Methods 624-S/625-5 or Methods 1624C/1625C detect
pesticides at very low concentrations. Without rrtegabore column
analysis, which may cost an additional 31,000, none of these
methods will do better than the detection limits, 20-50 ppb. For
some highly mixed pesticides such as chlordane, these methods can
only detect 200-300 ppb. At this lime, EPA is not.recommending
megabore column pesticide analysis nationally. However, in
situations where lower detection limits are crucial such as in
PCS or pesticide analysis, megabore column analysis is necessary.
3.4 PATHOGENIC MICROORGANISMS
A pathogen or pathogenic agent is any biological species
that can cause disease in the host organism (primarily humans).
These organisms fall into four broad categories: viruses,
3-26
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bacteria, parasites, and fungi. From these categories, species
commonly found in sewage sludge include fecal coliforms, fecal
streptococci, salmonella, and ascaris (helminth). Wastewater
sludge disinfection, the destruction or inactivation of
pathogenic organisms in the sludge, is carried out to minimize
piiblic health concerns regarding these and other microbial
agents.
The 40 CFR Part 257 regulations issued under joint authority
of Subtitle D of the Resource Conservation and Recovery Act
(RCRA) and Section 405(d) of the Clean Water Act establish
requirements for the disposal of solid waste which include
pathogens in sewage sludge. The regulations (40 CFR Part
257.3-6} require that sewage sludges applied to the land surface
or incorporated into the soil be treated by a Process to
Significantly Reduce Pathogens (PSRP). Public access must be
controlled for at least twelve months after sludge applications
and grazing by animals whose products are consumed by humans must
be prevented for at least one month after application. Treatment
by a Process to Further Reduce Pathogens (PFRP) is required for
sewage sludge applied to the land surface or incorporated into
the soil if crops for direct human consumption are grown within
eighteen months after application, if the edible portion of the
crop will touch the sludge.
Rather than requiring a specific reduction or concentration
for given pathogens, the process-based regulation (see Appendix
II of 40-CFR Part 257) describes and sets numerical requirements
for unit processes and operating conditions that qualify as PSRP
and PFRP (e.g., criteria for process time and temperature and for
volatile solids reduction). Thus permit compliance is based on
meeting process requirements, not pathogen reduction per se.
Appendix II of 40 CFR Part 257 allows methods or operating
3-27
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conditions other than those listed under PSRP or PFRP if
pathogens and vector attraction are reduced commensurate with the
reductions attainable from listed methods. Appendix II (of 40
CFR Part 257) does not prescribe the operation mode (i.e., batch
or continuous) for digesters. The regulation also does not
specify a method for calculating volatile solids reduction. For
a comprehensive discussion of the ways that volatile solids
reduction may be calculated and their limitations, refer to
Appendix B of this guidance document.
Although the 40 CFR Part 257 regulations are based on
specific processes rather than on meeting specific pathogen
reduction levels, the regulations do provide that other processes
"may be acceptable if pathogens are reduced to an extent
equivalent to the listed processes." In order to provide
guidance on the equivalence of these other methods EPA has a
panel of experts, the Pathogen Equivalency Committee (PEC), which
evaluates the acceptability of the process based on the level of
pathogen reduction, as determined by standardized analytical
tests. For more comprehensive information on pathogen and
guidance on whether alternative processes provide equivalent
levels of pathogen reduction consult the draft "Guidance for
Controlling Pathogens in Municipal Wastewater Sludge" PEC/EPA May
1989 (to be finalized July/August 1989).
Sampling techniques for determining pathogens in sewage
sludge are no different than for other tests except that no
preservatives are used. In the absence cf definitive sludge
methods for determining bacteria concentrations, modified
standard wastewater methods are often utilized. The analytical
methods for analysis of pathogens and indicator organisms are
provided in Table 3.6. Unfortunately no standardized rethods
exist for parasitic determinations.
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TABLE 3.6
ANALYTICAL TECHNIQUES FOR DETERMINATION OF PATHOGENIC MICROORGANISMS IN SEWAGE SLUDGE
Pathogen Preparation Technique Culture Media Reference
Fecal Colifo m A(908 or 909)
Fecal streptococcus/
enterococci. A(910A) or B
E. Coli Cent.rifugation and filtration M-PC broth membrane A(912E)
fi Iters
Salmonella sp. Filtration Brilliant green-xylose A(912C.l) or C
lysine desoxycholate agars
I
Animal Viruses Centrifugation, elutriation, Tissue culture D
filtration, and f.locculatJon
Helminth Ova Filtration A(917) or E
Protozoa Fj Itrat ion A ( 9 1 7 ) or E
A) APHA-AWWA-WPCF StandarcA Methods for the Examination of Water and Wastewater. 16th Ed.
B) Slantely, L.W. arid Bartley, "Numbers of enterococci in water, sewage, and feces
determined by the membrane filter technique with an improved medium", J. Bacteriology
11: 591-595 (1957).
(.:} Kenner, B.A., and Clark, "Detection-and enumeration of Salmonella and Pseudomonas
aeruginosa", J. water Pollution Control federation 46(9): 216.1-2171 (1974).
[)) "The Manual of Methods tor Virology", EPA/600/4-84/01'3 (February 1984) as revised.
E) Fox, J.C., Fitzgerald, and Lue-lling, "Sewage Organisms: A Color Atlas", Lewis
Publishers, Chelsea, Michigan (1981).
-------
The effectiveness of many PSRPs and PFRPs for reducing
pathogens can be estimated by measuring the effects on fecal
indicator organism densities (e.g., fecal coliform and/or fecal
streptococcus). These tests are less expensive and easier to run
than tests for specific pathogens and also provide good control
data.
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4. QUALITY ASSURANCE/QUALITY CONTROL
An essential part of a sampling and analysis program
includes a well designed quality assurance/quality control
(QA/QC) program. The extent of the QA/QC program should mirror
the intent and purpose of the sampling effort. It should be
noted that the facility is ultimately responsible for the quality
of the data even if a contractor is used. Therefore, it behooves
the POTW to have a good QA/QC program.
If the purpose of the sampling and analysis program is to
determine compliance with permit conditions, or to provide
critical data for maJcing a major cost decision, then the QA/QC
program should be extensive and be aiJle to demonstrate the
precision, accuracy, representativeness, comparability and
completeness of the data. The determination of these QA/QC
parameters and their definitions are as follows:
o QA is an overall program which guarantees the quality
of the product. It includes a QC auditing process to
prevent future defects. QA is synonymous with process
control, continuous improvement and prevention of poor
quality. QC is the examination of the product to
determine if it meets the specifications of the QA
program. QC is part of the overall QA program. QC is
synonymous with appraisal after the fact. An example
of QC is that lab duplicate results must be within a
certain percentage of each other or else the whole
batch must be redone.
o Laboratory QA includes prevention of data contamination
during laboratory procedures. Contamination may be due
to various other tests that are run in the lab at any
given time. In order to assure that any sample
contamination that does occur does not contaminate lab
data, a lab QA sample, usually a deionized water
"blank" (or other "clean" appropriate material), is run
along with the actual field samples. Lab QA also
includes doing duplicates and spikes of the actual
samples. Field QA serves the same purpose, to prevent
data from being erroneous. However, it is virtually
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impossible to prevent contamination of the samples
since the sampling environment is not controllable.
Therefore, the field blanks are subject to the same
conditions as the samples, i.e., the containers are
exposed to the environment as long as the sample
containers are open, the sample and field "blank" are
transported together.
o Accuracy, which is closeness to actual values, of all
sample testing and analyses should be evaluated at a
minimum frequency of 5 percent of the samples tested
(i.e., at least one in every 20 samples), using spiked
samples. Accuracy is calculated from the known and
analytically derived values of spiked parameters, and
expressed as percent recovery. The accuracy required
in the quality assurance program for the analyses is
specified in each of the EPA methods (e..g. , EPA 600 or
1SOO Series or EPA Methods for Chemical Analysis of
Water and_Wastes).
o Precision, which is repeatability of results, of sample
analyses should be evaluated at a minimum frequency of
5 percent (i.e. , at least one in every 20 samples) ,
using spiked samples in duplicate. Precision is
calculated from the analytical results of the. spiked
analytes in each set of duplicate samples., and
expressed as percent relative standard deviation. The
precision required in the quality assurance program for
the analyses is specified in each of the EPA Methods
(e.g., EPA 600 or 1600 series or EPA Methods for
Chemical Analysis of Water and Wastes).
o Completeness is calculated as the ratio of valid
measurements obtained to the number of valid
measurements needed to reach a predefined statistical
level of confidence in the resulting data.
Completeness is determined and evaluated en the basis
of data sets for each specific measurement process.
Data are considered to be valid if both the accuracy
and precision of the measurements meet the data quality
objective (i.e., accuracy, precision, and compliance
with analysis method protocol).
o All sampling should be performed using methods,
procedures, and controls that ensure the collection cf
representative samples which thus ensures that the
analytical results are representative of the media and
the conditions being measured.
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Comparability is a more qualitative QA measurement.
All analytical data must be calculated and reported in
units consistent with those specified in the applicable
permit. Previously developed data generated for each
facility about to be inspected is reviewed to ensure
that no difficulties of data comparability will be
encountered by following the specifications of the
permit. If no previous data exist and the permit
requirements are incomplete or ambiguous, data should
be reported in the standard units prescribed in the
appropriate EPA Methods (e.g., EPA 600 or 1600 series
or EPA Methods for Chemical Analysis of Water and
Wastes).
These QA/QC procedures are necessary for ensuring data quality.
On the other hand, if the purpose of the sampling effort is to
monitor plant performance for routine operation and maintenance
(O&M) decisions, a simplified QA program that includes sample
replicates and a field blank might suffice.
Sludge sampling and analysis programs for determining
compliance with permit conditions should include a written QA
Plan. EPA guidance for the development of a QA Program (EPA
Quality Assurance Project Plans (QAPP), 1983) identifies 16
elements which should be addressed in a QA plan:
Title Page
Table of Contents
Project Description
Project Organization and Responsibility
QA Objectives for Measurement Data in Terms of Precision,
Accuracy, Completeness, Representativeness, and
Comparability
Sampling Procedures and Frequency
Sample Custody
Calibration Procedures and Frequency
4-3
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Analytical Procedures
Data Reduction, Validation and Reporting
Internal Quality Control Checks
Performance and System Audits
Preventive Maintenance
Specific Routine Procedures Used to Assess Data Precision,
Accuracy and Completeness
Corrective Action
Quality Assurance Reports to Management
In preparing a QAPP, the QA parameters and specifications of
the analytical program should be dictated by the analytical
parameters. The QA parameters are specified in each analytical
protocol. There are situations (particularly for enforcement
actions) in which more stringent protocols will be desired.
In preparing the QA plans, the collection of field blanks
(blanks to reflect sample handling effects) and sample replicates
should be addressed. At a minimum, field blanks should be
collected every day that sampling is performed. Field blanks
should be prepared at the beginning of each sampling event, at
each discrete sampling site, by pouring American Society for
Testing and Materials (ASTM) Type II reagent-water ' into prepared
sample bottles. These sample bottles are randomly selected from
the supply of prepared sample bottles; a sample container should
be selected that is appropriate for each type of analysis for
which environmental samples are being collected (see Table 2.4).
The field blanks should be handled and analyzed in the same
manner as environmental samples. Because field blanks and
environmental samples are collected under the same conditions,
field blanks analyses should be used to indicate the presence of
4-4
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external contaminants that may have been introduced into samples
during collection.
One field replicate for every 20 samples or less should be
collected at a preselected POTW monitoring point. Field
replicates should be collected at the same time and in the same
manner as the other environmental samples. Results of the field
replicate analyses should be used primarily to assess the
precision of the field sampling methods.
In preparing and evaluating the analytical report, attention
should be given to the data quality, and the impact of both the
sampling and analysis data quality to the overall interpretation
of the analytical results. Both the data from the field QA
samples and the laboratory QA samples should be evaluated for the
presence of contaminants. Additionally, statistical procedures
should be used for the determination of precision, accuracy, and
completeness. The QAPP 1983 document provides a description of
the statistical procedures and their applications. All reports
of analytical data should contain a separate section which
assesses che quality of the reported data.
The sample procedures and frequency section of the quality
assurance plans should address, among other elements, sample
holding times, sample preservation procedures, and sample
chain-of-custody. Maximum sample holding times are presentee in
Table 2.4. Section 2.5.3 addresses sample preparation. Section
2.7.2 addresses sample chain-of-custody.
The section of the quality assurance plan on internal
quality control checks specifically discuss how the following
activities will be addressed:
4-5
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Organic Priority Pollutants
o Instrument tuning and calibration
o Method blank analysis
o Surrogate spike analysis
o Matrix spike/matrix spike duplicate analysis
o Internal standards analysis
Inorganic Priority Pollutants
o Initial calibration verification
o Continuing calibration verification
o Instrument response and linearity verification
o Calibration and preparation blank analyses
o Interference check sample analyses
o Spike sample analyses
o Duplicate sample analyses
o Quality control sample analyses
o Serial dilution analyses (if applicable)
o Instrument detection limit determination
o Method of standard additions abdication.
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5. SAMPLING AND ANALYTICAL COSTS
The cost of carrying out a sludge sampling program can vary
depending on the number and type of samples, parameters analyzed,
and whether analytical services are contracted out. The
following discussion examines sampling and analytical costs as of
April 1989.
5.I MANPOWER REQUIREMENTS
Manpower requirements fall into two categories: (1)
supervisory and program development, and (2) sampling/analytical.
All sampling programs should be designed and supervised by
qualified personnel. Developmental and supervisory needs will
vary according to the following factors:
o Type and number of samples
o Number of streams to be sampled
o Number of facilities/locations
o Availability of suitable sample points
o Parameters to be analyzed
o Experience and guaiifications of field and laboratory
personnel -
The number of factors influencing supervisory needs makes
estimating average costs for these needs impractical. Costs will
vary according to the hours needed for each program and according
to the salary range of qualified personnel within a given
organization.
Sampling manpower needs will ai^o vary widely depending on
the conditions listed above. For 24-hour composite sampling, a
5-1
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minimum- of two shifts (more likely three) are required. The
actual time spent sampling during the shifts will depend on how
frequently grab samples are collected (one per hour or once every
4 hours) during the 24-hour sampling period. In addition to the
manpower required to actually collect the sample, additional time
is required for sample preparation and handling. On-the-job
training is generally acceptable for sampling procedures.
Estimates of some of these needs are presented below:
TABLE 5.1
Activity Manpower
o
Automatic Sampler Setup1 0.5-4 manhours
o Sample Container 2-15 man-minutes
Preparation2 sample
o Sample Documentation3 2-15 man-minutes
sample
o Sample Handling4 2-60 man-minutes
sample
1 Depending on sample point characteristics.
2 Depending on parameter.
3 Depending on parameter, ultimate data use and number of points
sampled simultaneously.
4 Depending on parameters sampled and whether samples are
analyzed on site, are delivered or shipped.
5.2 IN-HOUSE ANALYTICAL COSTS
If any analytical work is done in-house, manpower,
equipment/facility and operating (i.e., electrical, chemical
supplies, etc.) costs will be incurred. Real costs will vary
according to what extent the analytical load imposed by the
sludge sampling is marginal to the laboratory's operational
5-2
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capacity. Two extremes serve as examples of this cost
variability.
A plant electing to do in-house analysis which has no
laboratory would need to make a sizable expenditure for an
adequate facility and the necessary analytical equipment and
supplies. In addition, qualified (B.S. Chemistry or equivalent)
laboratory personnel must be put on the payroll. Given these
circumstances, it would generally not be practical to do in-house
analysis. Instead, it is likely that this plant would contract
out for analytical services.
A second plant, conducting a similar sludge sampling
program, also elects to do all related analytical work in-house.
This plant, however, has. an analytical laboratory in place which
is capable of performing all analyses required. In addition, the
laboratory is presently operating below capacity. The additional
load imposed by the sludge sampling program will not require any
capital expenditure, and will require little, if any, additional
laboratory manpower (any additional manpower needs can be
accommodated by limited overtime rather than new employee hires).
In the case of this plant, in-house analysis for a sludge
sampling program can be accomplished at a very low real cost.
Because of the wide range of real costs possible for
sampling and in-house analytical work, no attempt is made herein
to quantify these costs on a dollars per sample basis. Rather,
each sampling program must be analyzed in light of applicable
salary scales, sampling program complexity and in-house
analytical capabilities.
5-3
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5.3 CONTRACT ANALYTICAL COSTS
Many sludge sampling programs, particularly those conducted
by small municipalities or authorities, will utilize contract
laboratories for analytical work. In contrast to sampling costs,
which vary greatly due to a wide variety of factors, contract
analytical costs fall within a relatively narrow range. Table
5.2 presents typical analytical costs for parameters commonly run
on sludge samples. These cost estimates were obtained in a March
1988 and 1989 telephone survey of analytical laboratories.
Two factors must be considered in estimating contract
analytical costs for sludge sampling programs. The first is the
need, depending on parameters, for additional preparation of
sludge samples prior to analysis. Many laboratories charge an
additional fee for this preparation, which can be as much as
$100, depending on the parameters to be run.
The second factor impacting analytical costs is the practice
by most laboratories of offering discounts on per sample prices
for multiple sample analysis. These discounts vary from
laboratory to laboratory, and can be substantial depending on the
number of samples involved. Of particular importance is the
number of samples being received simultaneously by the laboratory
(i.e., a greater discount will typically be offered for 10 sam-
ples if all are to be analyzed at one time rather than if one is
to be delivered to the lab each week for 10 weeks).
5.4 SAMPLING EQUIPMENT COSTS
The cost of sampling equipment and containers is typically a
relatively small fraction of the overall cost of a sludge
sampling program. In general, the manual collection methods used
for sludge sampling require only simple, relatively inexpensive
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TABLE 5.2
TYPICAL CONTRACT ANALYTICAL COSTS FOR
COMMONLY ANALYZED SLUDGE PARAMETERS
COST RANGE ($/SAMPLE)
Washington District of
State Columbia California Massachusetts
Priority Pollutants
Organics Methods:
1624C/162SC 2200-2400
Office of Solid 250
Waste #8240
624-S/625-S 1800-2200 425 550
Acid Fraction Only N/A N/A 225
Base Neutral Only N/A N/A 325
Metals:
ICAP or AAS 25-200/metal 240/U3) 290/(13)
Others:
Cyanide 20-30 75 60
Phenols 20-30 75 50
Total PCBs 60-150 200 175
Pesticides included 150
in above
Total for Priority Scan without Dioxin
2225-5210 1265 1275
Other Won Priority _Pollutants
Oil & Grease 15-25
" total grav. 60
" HC " 80
11 HC & tot " 130
11 IR method 100
Ammonia, as N 10-20 35
Tot Kjeldahl N 10-20 35
Tot Suspend Sol 10-20 15
Tot % Solids 10-20 15
Tot Phosphorus 10-20 35
Phosphate 10-50 35
Potassium 20-30 15
Tot Org Halides 50-100 80
EP Toxicity
extraction N/A 100 75
8 metals 140 185
2 pest. 100 150
4 nerb. 150 175
TOTAL SP $ 420 $490 $585
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equipment. The following paragraphs highlight the primary
equipment cost items in a typical sludge sampling program.
Sample Containers - Sample container costs are related
to: (1) the number of containers needed, and (2) the
type of container needed, depending on parameter(s) to
be analyzed. The following are typical per-container
prices for some commonly used containers:
Container
Teflon
Graduated Glass
(w/TefIon-lined cap)
Polypropylene
Polypropylene
Polypropylene
Glass
(w/Teflon lined cap)
1 liter
1 liter
1 liter
0.5 liter
10 liter
0.5 liter
Approx. Price
$ 35 - 40
S 3-4
$ 2
$ 1.50
$ 15
$ <1 - 2
As with analytical costs, suppliers of containers often
offer substantial discounts for volume purchases.
Automatic Samplers - In most sludge sampling programs
the use of automatic sampling equipment win be
precluded due to sample characteristics. If automatic
sampling is utilized in a given sampling program,
automatic sampler costs will typically constitute the
majority of sampling equipment costs. Portable,
battery-powered peristaltic-type samplers typically
cost from $1000 to $3000, depending on features such as
computerized controls, etc. Pneumatically operated
plunger-type samplers will vary in price according to
application and capacity.
Manual Sampling Equipment - In general, equipment
costs for manual sludge sampling are minimal.
Stainless steel pitchers (2 liter), which are useful
for sampling from either a tap or an open channel flow,
are available for approximately $20. Polypropylene
pitchers typically cost about 1/2 of the price of
stainless steel. Stainless steel scoops used for
sludge caJce sampling cost approximately $40 (depending
on size), while aluminum scoops of similar size are
available for less than $10.
Preservatives - Reagent grade chemicals should be used
as preservatives. Since each sample will typically
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require very small amounts of preservatives, cost on a
per sample basis is negligible.
5.5 OPPORTUNITIES FOR COST SAVINGS
To provide a representation of sludge quality over a fixed
duration, sewage sludge can be composited (i.e. mixed), reducing
the number of samples to be analyzed. In light of the high costs
associated with analysis of priority pollutant organics in sewage
sludge, compositing samples provides an opportunity to
Substantially lower analytical co-sts. Field compositing is not
an appropriate technique to use when the sample will be analyzed
for volatile components. Lab personnel can composite graJb
samples in the lab.
When interested in daily variation in sludge constituents, a
POTW can collect and analyze 24-hour composite samples, each
consisting of six or more gra±> samples. This represents a
significant cost savings when compared to separately analyzing
many individual, non-composited samples. Smaller POTWs, with
less variation in sludge quality, may elect to composite samples
over several days as opposed to 24-hour composites. The
suitability cf a multi-day compositing procedure will depend upon
whether the specific sludge constituent can be adequately
preserved in the sludge sample. Table 2.3 shows the recommended
preservatives and maximum sample holding times for organic and
metal pollutants.
Another way to reduce costs would be to sample more
frequently for parameters that are relatively inexpensive to
analyze such as metals, nitrogen, phosphorus, and potassium, and
to test for organic pollutants (expensive) less frequently, so
long as some data are available indicating that the levels of
organic contaminants in the sludge are acceptable.
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6. REFERENCES
APHA-AWWA-WPCF. 1976. "Standard Methods for the Examination of
Water and Wastewater". Washington, B.C.: APHA-AWWA-WPCF.
Black, C.A. (ed.). 1965. "Methods of Soil Analysis, Agronomy
Monograph No. 9." Madison, Wisconsin: American Society of
Agronomy.
Colby, Bruce N., and Ryan, Philip W. 1986. "Initial Evaluation
of Methods 1634 and 1635 for the Analysis of Municipal Wastewater
Treatment Sludges by Isotope Dilution GC/MS". Washington, B.C.:
U.S. Environmental Protection Agency, Office of Water Regulations
and Standards.
"Criteria for Classification of Solid Waste Disposal Facilities
and Practices," 40 CFR Part 257. Washington, D.C.: National
Archives and Records Administration, Office of the Federal
Register.
EPA. 1974. "Process Design Manual for Sludge Treatment and
Disposal", EPA625/1-74-006. Washington, D.C.: U.S.
Environmental Protection Agency, Office of Technology Transfer.
EPA. 1976. '"Analytical Methods for Trace Metals",
EPA-430/1-76-002. Cincinnati, OH: U.S. Environmental Projection
Agency, National Training and Operational Technology Center.
EPA. 1977. "The Sources and Behavior of Heavy Metals in
Wastewater and Sludges", EPA-600/2-77-070. Cincinnati, OH: U.S.
Environmental Protection Agency, Municipal Environmental Research
Laboratory.
EPA. 1978a. "Microbiological Methods for Monitoring the
Environment, Water and Wastes", EPA-600/8-78-017. Cincinnati,
OH: U.S. Environmental Protection Agency, Environmental
Monitoring and Support Laboratory.
EPA. 1978b. "Validity of Fecal Coliforms, Total Coliforms, and
Fecal Streptococci as Indicators of Viruses in Chlorinated
Primary Sewage Sludge Effluents", EPA-600/J-78-175. Cincinnati,
OH: U.S. Environmental Protection Agency, Environmental
Monitoring and Support Laboratory.
EPA. 1979a. "Methods for Chemical Analysis of Water and Wastes" ,
EPA-600/4-79-020. Cincinnati, OH: U.S. Environmental Protection
Agency, Environmental Monitoring and Support Laboratory.
6-1
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EPA. 1979Jb. "Process Design Manual - Sludge Treatment and
Disposal", EPA 625/1-79-011. Cincinnati, OH: U.S. Environmental
Protection Agency, Municipal Environmental Research Laboratory.
EPA. 1981. "Parasites in Southern Sludges and Disinfection by
Standard Sludge Treatment", EPA-600/2-81-166. Cincinnati, OH:
U.S. Environmental Protection Agency, Municipal Environmental
Research Laboratory.
EPA. 1983a. "Process Design Manual - Land Application of
Municipal Sludge", EPA-625/1-83-016. Cincinnati, OH: U.S.
Environmental Protection Agency, Municipal Environmental Research
Laboratory.
EPA. 1983b. "Interim Guidelines and Specifications for
Preparing Quality Assurance Project Plans". PB83-170514,
QAMS-005/80. Office of Research and Development.
EPA. 1984a. "Multielemental Analytical Techniques for Hazardous
Waste Analysis: The State-of-the-Art", EPA-600/4-84-028. Las
Vegas, NV: U.S Environmental Protection Agency, Environmental
Monitoring systems Laboratory.
EPA. 1984b. "Interim Methods for the Measurement of Organic
Priority Pollutants in Sludges". Cincinnati, OH: U.S.
Environmental Protection Agency, Environmental Monitoring and
Support Laboratory.
EPA. 1984c. "Development of Analytical Test Procedures for the
Measurement of Organic Priority Pollutants in Sludge",
EPA-600/4-84-001. Cincinnati, OH: Environmental Monitoring and
Support Laboratory.
EPA. 1984d. "USEPA Manual of Methods of Virology",
EPA-600/4-34-013. Cincinnati, OH: U.S. Environmental Protection
Agency, Environmental Monitoring and Support Laboratory.
EPA. 1986a. "Proceedings: Workshop on Effects of Sewage Sludge
Quality and Soil Properties on Plant -Uptake of Sludge - Applied
Trace Constituents". Las Vegas, NV: U.S. Environmental
Protection Agency, Office of Research and Development.
EPA. I986b. "Test Methods for Evaluating Solid Waste, SW-846".
Washington, D.C.: U.S. Environmental Protection Agency, Office
of Solid Waste and Emergency Response.
EPA. 1987. "Preparation Aid for HWERL's Category II Quality
Assurance p-oject Plans". Cincinnati, OH: U.S. Environmental
Protection Agency, Office of Research and Development.
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EPA. 1988a. "Analytical Methods for the National Sewage Sludge
Survey". Washington, D.C.: U.S. Environmental Protection
Agency, Office of Water Regulations and Standards.
EPA. 1988b. "Draft Guidance for Writing Case-by-Case Permit
Requirements for Municipal Sewage Sludge". Washington, D.C.:
U.S. Environmental Protection Agency, Office of Water Enforcement
and Permits.
EPA. 1988c. "Strategy for Interim Implementation of Sludge
Requirements in Permits". Washington, B.C.: U.S. Environmental
Protection Agency, Office of Water Enforcement and Permits (final
due August 1989).
EPA. 1989. "Control of Pathogens in Municipal Wastewater Sludge
for Land Application". (Draft May 1989, final due Augusr 1989).
"Guidelines for Establishing Test Procedures for the Analysis of
Pollutants," 40 CFR Part 136. Washington, D.C.: National
Archives and Records Administration, Office of the Federal
Register.
"Memorandum: Pathogen Equivalency Committee," U.S. Environmental
Protection Agency, Office of Water, November 2, 1987.
Metcalf and Eddy, Inc. 1979. Wastewater Engineering.
Treatment, Disposal, Reuse. New York: McGraw-Hill Book Company.
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APPENDIX A
CHAIN OF CUSTODY RECORD
-------
Chain of Custody Record
W.O. No.
Project Name
Samplers: (Signature)
Sta. No.
Date
Time
Relinquished By: (Signature)
Station Description
Date
Time
Sample
Type
Number
and
Type of
Containers
Remarks
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Source: 1987 tPA Document 'Piepacalion Aid for IIWlKl't (.attijmy II Quality AHumiue Piojtxl flam'
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APPENDIX B
DETERMINATION OF VOLATILE SOLIDS
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DETERMINATION OF VOLATILE SOLIDS
REDUCTION IN DIGESTION1
By J.B. Farrell
INTRODUCTION
Vhen sewage sludge is utilized on land, Federal regulations require that
it be treated by a "process to significantly reduce pathogens" (PSRP) or a
"process to further reduce pathogens" (PFRP). A requirement of both of these
steps is a reduction in "vector attraction" of the sludge. If the PSRP or
PFRP is anaerobic or aerobic digestion, the requirement for vector attraction
reduction is achieved if volatile solids are reduced by 38 percent. As
Fischer1 has noted, the Federal regulation2 does not specify a method for
calculating volatile solids reduction. Fischer observed that the United
Kingdom has a similar requirement for volatile solids reduction for digestion
(40 percent), but also failed to prescribe a method for calculating volatile
solids reduction. Fischer has provided a comprehensive discussion of the
vays that volatile solids reduction may be calculated and their limitations.
He presents the following equations for determining volatile solids reduction:
1. Full mass balance equation
2. Approximate mass balance equation
3. "Constant ash" equation
4. Van Kleeck equation
The full mass balance equation is the least restricted but requires more
information than is currently collected at a wastevater treatment plant. The
approximate mass balance equation assumes steady state conditions. The
"constant ash" equation requires the assumption of steady state conditions as
well as the assumption that ash input rate equals ash output rate. The Van
Kleeck equation, vhich is the equation generally suggested in publications
originating in the United States is equivalent to the "constant ash"
equation. Fischer calculates volatile solids reduction using a number of
1Source: "Control of Pathogens in Municipal Vastewater Sludge," EPA, to be
published August, 1989.
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examples of considerable complexity and illustrates that the different methods
frequently yield different results. He closes vith the recommendation,
obviously directed to rulemakers, that "if it is necessary to specify a
particular value for FVSR (fractional volatile solids reduction) then the
specification should indicate the method of calculation of FVSR."
Fischer's paper is extremely thorough and is highly recommended for
someone trying to develop a deep understanding of potential complexities in
calculating volatile solids reduction. Hovever, it was not written as a
guidance document for field staff faced with the need to calculate volatile
solids reduction in their own plant. The nomenclature is precise but so
detailed that it makes comprehension difficult. In addition, two important
troublesome situations that complicate the calculation of volatile solids
reduction—grit deposition in digesters and decantate removal—are not
explicitly dismissed. Consequently, this presentation has been prepared to
present guidance that describes the major pitfalls likely to be encountered in
calculating volatile solids reduction and assists the practitioner of
digestion to the best route to take for his situation.
The recommendation of this presentation is not the same as Fischer's. He
suggests that the authorities should have provided a calculation method vhen
they required specific volatile solids reductions. From a review of Fischer's
results and this presentation, it will be clear that sometimes very simple
calculations vill give correct results and in other cases the simple methods
will yield results seriously in error. Selecting one method and requiring
that it be followed is excessively restrictive. The best solution is to
require that the calculation be done correctly and then provide adequate
guidance. This presentation attempts, belatedly, to provide that adequate
guidance.
It is important to note that the calculations of volatile solids
reduction will only be as accurate as the measurement of volatile solids
content in the sludge streams. The principal cause of error is poor sampling.
Samples should be representative, covering t1 e entire charging and withdrawal
periods. Averages should cover extended periods of time during which changes
in process conditions are minimal. For some plants it is expected that
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periodic checks of volatile solids reduction will produce results so erratic
that no confidence can be placed in them. In this case, adequacy of
stabilization can be verified by the method suggested in the text —
periodically batch digest the product for 40 days. If VS reduction is less
than 152, the product is sufficiently stable.
The Equations for FVSR
The equations for fractional volatile solids reduction (FVSR) that will
be discussed below are the same as developed by Fischer1, except for omission
of his "constant ash" equation. This equation gives identical results to the
Van Kleek equation so it is not shown. Fischer's nomenclature has been
avoided or replaced vith simpler terms. The material balance approaches are
called "methods" rather than "equations." The material balances are drawn to
fit the circumstances. There is no need to formalize the method with a rigid
set of equations.
In the derivations and calculations that follow, both VS (total volatile
solids content of the sludge or decantate on dry solids basis) and F/SR are
expressed throughout as fractions to avoid the frequent confusion that occurs
when these terms are expressed as percentages. "Decantate" is used in place
of the more commonly used "supernatant" to avoid the use of "s" in subscripts.
Similarly, "bottoms" is used in place of '"sludge" to avoid use of "s" in
subscripts.
The "full mass balance" method
The "full mass balance" method must be used when steady conditions do not
prevail over the time period chosen for the calculation. The chosen time
period must be substantial, at least twice the nominal residence time in the
digester (nominal residence time = average volume of sludge in the digester +
average volumetric flow rate. Note: when there is supernatant withdrawal,
volume of sludge withdrawn should be used to calculate average volumetric flow
rate). The reason for the long time period is to reduce the influence of
short-term fluctuations in feed or product flow rates or compositions. If
input compositions have been relatively constant for a long period of time,
then the time period can be shortened.
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An example vhere the full mass balance method vould be needed is an
aerobic digester operated as follows:
1. Started with the digester 1/4 full (Time zero).
2. Rav sludge is fed to the digester daily until digester is full.
3. Supernatant is periodically decanted and rav sludge is charged into
the digester until not enough settling occurs to accommodate daily
feeding. (Hopefully this will not occur until enough days have
passed for adequate digestion.)
4. Draw down the digester to about 1/4 full (final time), discharging
the sludge to sand beds.
The full mass balance is written as follows:
Sum of total volatile solids inputs in feed streams
during the entire digestion period = sum of volatile
solids outputs in withdrawals of decantate and bottoms *
loss of volatile solids + accumulation of volatile
solids in the digester. (1)
Loss of volatile solids is calculated from Equation 1. FVSR is calculated by
Equation 2:
FVSR = loss in volatile solids
sum of volatile solids inputs (2)
The accumulation of volatile solids in the digester is the final volume
in the digester after the drawdowns times final volatile solids concentration
less the initial volume at time zero times the initial volatile solids
concentration.
To properly determine FVSR by the full mass balance method requires
determination of all feed and withdrawal volumes, initial and final volumes in
the digester and determination of volatile solids concentrations on all
streams. In some cases, which will be discussed later, simplifications are
possible.
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The "approximate mass balance" method
If volumetric inputs and outputs are relatively constant on a daily
basis, and there is no substantial accumulation of volatile solids in the
digester over the time period of the test, an approximate mass balance (AMB)
may be used. The basic relationship is stated simply:
volatile solids input rate = volatile solids output
rate + loss of volatile solids. (3)
The FVSR is given by Equation 2.
No decantate, no grit accumulation - Calculation of FVSR is illustrated
for Problem 1 in Table 1 vhich represents a simple situation with no decantate
removal and no grit accumulation. An approximate mass balance is applied to
the digester operated under constant flow conditions. Since no decantate is
removed volumetric flow rate of sludge leaving the digester equals flow race
of sludge entering. Applying Equations 3 and 2,
FYf = BYb + loss (4)
Loss = 100 (50-30) = 2000 (5)
FVSR = Loss (6)
FYf
FVSR = 2000 = 0.40 (7)
(100)(50)
Nomenclature is given in Table 1. Note that the calculation did not
require use of the fixed solids concentrations.
The calculation is so simple that one venders vhy it is so seldom used.
One possible reason is that the input and output volatile solids concen-
trations (Yf and Yfe) may show greater coefficients of variation (standard
deviation * arithmetic average) than the fraction volatile solids (VS,
fraction of the sludge solids that is volatile—note the difference between VS
and Y).
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Grit deposition - Grit deposition can be a serious problem in both
aerobic and anaerobic digestion. The biological processes that occur in
digestion dissolve or destroy the substances suspending the grit and it tends
to settle. If agitation is inadequate to keep the grit particles in
suspension they will accumulate in the digester. The approximate mass balance
can be used to estimate accumulation of fixed solids.
For Problem 1, the balance yields the following:
FX, = BXV •»• loss (8)
i o
(100)(17) = (100)(17) + Fixed Solids Loss (9)
Fixed Solids Loss =0 (10)
The material balance compares fixed solids in output vith input. If some
fixed solids are missing this loss term will be a positive number. Since we
know that digestion does not consume fixed solids, ve assume that the fixed
solids are accumulating in the digester. As Equation 10 shows, the fixed
solids loss equals 2ero. Note that for this case where input and output
sludge flow rates are equal, the fixed solids concentrations are equal vhen
there is no grit accumulation.
The calculation of fixed solids is repeated for Problem 1. Conditions in
Problem 2 have been selected to show grit accumulation. Parameters are 'he
same as in Problem 1 except for the fixed solids concentration (Xb) and
parameters related to it. Fixed solids concentration in the digested sludge
is lower than in Problem 1. Consequently, VS is higher and mass flov rate of
solids (input rate = output rate •>• rate of loss of fixed solids) is presented
in Equation 11-13.
FXf = BXfc + Fixed Solids Loss (11)
Fixed Solids Loss = FX, - BXb (12)
Fixed Solids Loss = (100)(17) - (100)(15) = 200 kg/d (13)
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The material balance, which only looks at inputs and outputs, informs us
that 200 kg/d of fixed solids have not appeared in the outputs as expected.
Ve knov that fixed solids are not destroyed and conclude that they are
accumulating in the bottom of the digester. The calculation of FVSR for
Problem 2 is exactly the same- as for Problem 1 (see Equations 4-7) and yields
the same result. The accumulation of solids does not change the result.
Decantate withdrawal, no grit accumulation - In Problem 3, supernatant is
withdrawn daily. Volatile and fixed solids concentrations are known for all
streams but the volumetric flow rates are not known for decantate and bottoms.
It is impossible to calculate FVSR without knowing the relative volume balance
and a fixed solids balance, provided it can be assumed that loss of fixed
solids (i.e., accumulation in the digester) is zero.
Selecting a basis for F of 100 m3/d,
Volume balance: 100 = B + D (11)
Fixed solids balance: 100 X. = BXb + DXd (12)
Since the three Xs are known, B and D can be found.
Substituting 100-D for 3 and the values for the Xs from Problem 3 and
solving for D and B.
(100)(17) = (100 -DX23.50) + (D)(7.24) (13)
D = 40.0 m3/d, B = 60.0 m3/d (14)
The FVSR can now be calculated by drawing a volatile solids balance:
FY, = BYfa * DYd + loss (15)
loss = FYf - BYfe - DYd
FVSR = (16)
FYf FY,
FVSR = (100)(50) - (60K41.42) - (4Q)(12.76) « 0.40 (17)
(100)(50)
Unless information is available on actual volumes of decantate and
sludge, there is no way to determine whether grit is accumulating in the
digester. If it is accumulating, the calculated FVSR will be in error.
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When we make the calculation shown in Equation 15-17, ve assume that the
volatile solids that are missing from the output streams are consumed by
biological reactions that convert them to carbon dioxide and methane, Ve
assume accumulation is negligible. Volatile solids are less likely to
accumulate than fixed solids but it can happen. In poorly mixed digesters,
the scum layer that collects at the surface is an accumulation of volatile
solids. FVSR calculated by Equations 15-17 will be overestimated if volatile
solids accumulation rate is substantial.
Decantate withdrawal and grit accumulation - In Problem 4, there is
suspected grit accumulation. The quantity of B and D can no longer be
calculated by Equations 11 and 12 because Equation 12 is no longer correct,
The values of B and D must be measured. All parameters in Problem 4 are the
same as Problem 3 except measured values for B and D are introduced into
Problem 4. Values of B and D calculated assuming no grit accumulation
(Problem 3—see previous section), and measured quantities are compared belov:
Calculated Measured
B 60 49.57
D 40 50.43
The differences in the values of B and D are not large but they make a
substantial change in the numerical value of FVSR. The FVSR for Problem 4 is
calculated belov:
FVSR = (100)(50) - (49.57)(41.42) - (50.43)(12.76) =0.461 (18)
(100)(50)
If it had been assumed that there was no grit accumulation, FVSR vould equal
0.40 (see Problem 3). It is possible to determine the amount of grit
accumulation that has caused this change. A raaterial balance on fixed solids
is drawn:
FXf = BXb + DXd + Fixed Solids Loss (19)
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The fractional fixed solids loss due to grit accumulation is found by
rearranging this equation:
Fixed Solids Loss FX, - BX - DX, (20)
6 d
FXf FXf
Substituting in the parameter values for Problem 4.
Fixed Solids Loss = (100)(17) - (49.57)(23.50) - (50.43)(7.24) (21)
FXf (100)(17)
= 0.100
If this fixed solids loss of 10 percent had not been accounted for, the
calculated FVSR would have been 13 percent lower than the correct value of
0.461. Note that if grit accumulation occurs and it is ignored, calculated
FVSR vill be lower than the actual value.
The Van Kleeck Equation
Van Kleeck first presented his equation vithout derivation in a footnote
for a review paper on sludge treatment processing in 1945''. The equation is
easily derived from total solids and volatile solids mass balances around :he
digestion system. Consider a digester operated under steady state conditions
vith decantate and bottom sludge removal. A total solids mass balance and a
volatile solids mass balance are:
Mf = Mfa -r Md + (Loss of total solids) (22)
M.'VSj = VVSb * Md'VSd * (Loss of v°latile solids) (23)
The masses must be mass of solids rather than total mass of liquid and solid
because VS is an unusual type of concentration unit — it is "mass of volatile
solids per unit mass of total solids."
It is now assumed that fixed solids are not destroyed and there is no
grit deposition in the digester. The losses in Equations 22 and 23 then
comprise only volatile solids so the losses are equal. It is also assumed
that the VS of the decantate and of the bottoms are the same. This means that
the bottoms may have a much higher solids content than the decantate but the
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proportion of volatile solids to fixed solids is the same for both streams.
Assuming then that VSb equals VSd and making this substitution in the defining
equation for FVSR (Equation 2),
Loss of vol. solids = 1 - (M + M ) VS.
FVSR « (24)
Mf-VSf M,-VSf
From Equation 22, recalling that ve have assumed that loss of total
solids equals loss of volatile solids,
Mb + Md * Mf - loss of vol. solids (25)
Substituting for Mb + Md into Equation 24,
(M, - Loss of vol. solids)
FRVS = 1 - — -VS. (26)
„ 5
Simplifying further,
FRVS »!-(!- FRVS)-VS. (27)
VS.
Solving for FRVS,
VS. - VSb
FRVS =
vs, - vs;-vsb
This is the form of the Van Kleeck Equation found in UPCF's Manual of
Practice No. 16 . Van Kleeck presented the equation in the
following equivalent form:
VSb-(l - VS )
1 (29)
VS,-(1 - VS. )
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The Van Kleeck Equation is applied below to Problems 1-4 in Table 1 and
compared to the approximate mass balance equation results:
Approximate Mass Balance (AMB) 0.40 0.40 0.40 0.461
Van Kleeck (VK) 0,40 0.318 0.40 0.40
Problem 1: No decantate and no grit accumulation. Both methods give
correct answers.
Problem 2: No decantate but grit accumulation. VK is invalid and
incorrect.
Problem 3: Decantate but no grit accumulation. AMB method is valid VK
method is valid only if VS. = VS..
*— o a
Problem 4: Decantate and grit acumulation. AMB method valid only if B
and D are measured. VK method is invalid.
The Van Kleeck equation is seen to have serious shortcomings when applied
to certain practical problems. The AMB method can be completely reliable
vhereas the Van Kleeck method is useless under some circumstances.
Review and Discussion of Calculation Methods and Results
Complete Mass Balance Method - The complete mass balance method allows
calculation of volatile solids reduction of all approaches to digestion, even
processes where final volumes in the digester does not equal initial volume
and where daily flows are not steady. A serious drawback is the need for
volatile solids concentration and volumes of all streams added to or withdrawn
from the digester as well as initial and final volumes and concentrations in
the digester. This can be a daunting task particularly for the small plants
which are most likely to run their digesters in other than steady flow modes.
For plants of this kind, an "equivalent" method that shows that the sludge has
undergone the proper volatile solids reduction is likely to be a better choice
than trying to demonstrate 38 percent volatile solids reduction. An aerobic
sludge has received treatment equivalent to a 38 percent volatile solids
reduction if specific oxygen uptake rate is below a specified maximum.
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Anaerobically digested sludge has received treatment equivalent to a 38
percent volatile solids reduction if volatile solids reduction after batch
digestion of the product sludge for 40 days is less than a specified maximum .
Approximate Mass Balance (AHB) Method - The approximate mass balance
method assumes that daily flows are steady and reasonably uniform in com-
position, and that digester volume and composition does not vary substantially
from day to day. Results of calculations and an appreciation of underlying
assumptions shov that the method is accurate for all cases, including vith-
drawal of decantate and deposition of grit, provided that in addition to
composition of all streams the quantity of decantate and bottoms (the digested
sludge) are knovn. If the quantities of decantate and bottoms are not kjiovn,
the accumulation of grit cannot be determined. If accumulation of grit is
substantial and FVSR is calculated assuming it to be negligible, FVSR will be
lower than the true value. The result is conservative and could be used to
shov that minimum volatile solids reductons are being achieved.
The Van Kleeck Equation - The Van Kleeck Equation has underlying
assumptions that should be made clear vherever the equation is presented. It
is never valid vhen there is grit accumulation because it assumes the fixed
solids input equals fixed solids output. Fortunately, it produces a ""con-
servative result in this case. Unlike the AMB method it does not provide a
convenient vay to check for accumulation of grit. It can be used vhen
decantate is vithdravn provided VSb equals VSd. Just how big the difference
betveen these VS values can be before an appreciable error in FVRS occurs is
unknovn, although it could be determined by making up a series of problems
with increasing differences betveen the VS values, calculating FRVS using the
AMB method and a Van Kleeck equation, and comparing results.
The shortcomings of the Van Kleeck equation are substantial and may
eventually lead to a recommendation not to use it. Hovever, it has one strong
point. The VS of the various sludge and decantate streams are likely to shov
much lover coefficients of variation (standard deviation -r arithmetic average)
than volatile solids and fixed solids concentration. Reviev of data are
needed to determine hov seriously the variation in concentrations affect the
confidence interval of FVSR calculated by both methods. A hybrid approach may
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turn out to be advantageous. The AMB method could be used first to determine
if grit accumulation is occurring. If grit is not accumulating, the Van
Kleeck equation could be used. If decantate is withdrawn, the Van Kleeck
equation still cannot be used unless VSb is nearly equal to VSd .
Average Values - The concentrations and VS values used in the equations
will all be averages. For the material balance methods, the averages should
be weighted averages according to the mass of solids in the stream in
question. The example below shows how to average the volatile solids con-
centration for four consecutive sludge additions.
Volatile Solids
Addition Volume Concentration
1
2
3
4
Y av =
10 m3
73
m
15 m3
12 m3
10 X 50 + 7 X 45 4
50 kg/m3
45 kg/m3
40 kg/m3
52 kg/m3
- 15 X 40 * 12
X 52
____^ (30)
10 +• 7 + 15 * 12
For the Van Kleeck equation, the averages of VS are required. Properly
they should be weighted averages based on the weight of the solids in each
component of the average although an average weighted by the volume of the
component or an arithmetic average may be sufficiently accurate if variation
in VS is small. The following example demonstrates the calculation of all
three averages.
Total Solids
Addition Volume
1 12 m3
2 8m3
3 13 m3
4 10 m3
Concentration
72 kg/m3
50 kg/m3
60 kg/m3
55 kg/m3
VS
0.75
0.82
0.80
0.77
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Weighted by Mass
VS av = 12 X 72 X 0.75 * 8 X 50 X 0.82
+ 13 X 60 X 0.80 + 10 X 55 X 0.77 (31)
12 X 72 + 8 X 50 + 13 X 60 + 10 X 55= 0.795
Weighted by Volume
VS av = 12 X 0.75 + 8 X 0.82 + 13 X 0.80 + 10 X 0.77 (32)
12 + 8 + 13 + 10 = 0.783
Arithmetic Average
VS av = 0.75 + 0.82 + 0.80 + 0.77 (33)
5= 0.785
In this example the arithmetic average vas nearly as close as the volume-
weighted average to the mass-weighted average, vhich is the correct value.
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LITERATURE CITED
Fischer, W.J., "Calculation of volatile solids during sludge digestion,"
p 499-529, in Bruce A. (ed.) "Sewage Sludge Stabilization and
Disinfection," pub. for Water Research Centre by E. Horwood Ltd.,
Chichester, England (1984).
U.S. EPA, Code of Federal Regulations, Title 40, part 257 (40 CFR 257),
"Part 257—Criteria for Classification of Solid Waste Disposal Facilities
and Practices."
Water Pollution Control Federation, Manual of Practice No. 16, "Anaerobic
Sludge Digestion," pub. Water Pollution Control Federation, Washington, DC
(1968).
Van Kleeck, L.W., Sewage Works J., 17 (6), 1240-1255 (1945), "Operation of
sludge drying and gas utilization units," Refer to footnote on p 1241.
U.S. EPA, "Technical Support Document: Pathogens," pub. by EPA's Office
of Water Regulation and Standards, Washington, DC (1989).
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TABLE 1
QUANTITATIVE INFORMATION FOR EXAMPLE PROBLEMS l'J'
Parameter
Nominal residence time
Time period for averages
Feed Sludge
Volumetric flow rate
Volatile solids concentration
Fixed solids concentration
Fraction volatile solids
Mass flow rate of solids
Digested Sludge (Bottoms)
Volumetric flow rate
Volatile solids concentration
Fixed solids concentration
Fraction volatile solids
Mass flow rate of solids
Decantate
Volumetric flow rate
Volatile solids concentration
Fixed solids concentration
Fraction volatile solids
Mass flow rate of solids
Symbol
9
F
i.
D
Units
d
d
3
kg/ra3
kg/m3
kg/kg
kg/d
kg/m
kg/m
kg/kg
kg/d
Problem Statement Number
kg/m
kg/kg
kg/d
1
20
60
2
20
60
1
20
60
*
20
60
100 100
50 50
17 17
0.746 0.746
6700 6700
100 100
30 30
17 15
0.638 0.667
4700 4500
100 100
50 50
17 17
0.746 0.746
6700 6700
41.42
23.50
0.638
49.57
41.42
23.50
0.638
0 0 50.43
- 12.76 12.76
7.24 7.24
- 0.638 0.638
1. Condi ions are steady state; all daily flows are constant. Volatile solids are not accumulating in the
digester, although grit may be settling out in the digester.
2. Numerical values are given at 3 or 4 significant figures. This is unrealistic considering the expected
accuracy in measuring solids concentrations and sludge volumes. The purpose of extra significant figures
is to allow more understandable comparisioiu; to lie made of the different calculation methods.
3. All volatile solids concentrations are based on the total solids, not merely on the suspended solids.
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