SLUDGE HANDLING
AND
DISPOSAL PRACTICES
AT
SELECTED MUNICIPAL WASTEWATER
TREATMENT PLANTS
APRIL 1977
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF WATER PROGRAM OPERATIONS
MUNICIPAL CONSTRUCTION DIVISION
WASHINGTON, D.C. 20460
MCD-36
-------
EPA REVIEW NOTICE
This report has been reviewed by the Environmental Protection Agency and
approved for publication. Approval does not signify that the contents
necessarily reflect the views and policies of the Environmental Protection
Agency, nor does mention of trade names or commercial products constitute
endorsement or recommendation for use. In this report there is no
attempt by EPA to evaluate the practices and methods reported.
NOTES
To order this publication, MCD-36, "Sludge Handling and Disposal Practices
at Selected Municipal Wastewater Treatment Plants," write to:
General Services Administration (8FFS)
Centralized Mailing Lists Services
Building 41, Denver Federal Center
Denver, Colorado 80225
Please indicate the MCD number and title of publication.
-------
E P A-430/9-77-007
APRIL 1977
SLUDGE HANDLING AND DISPOSAL PRACTICES
AT SELECTED MUNICIPAL WASTEWATER
TREATMENT PLANTS
by
Sverdrup & Parcel and Associates, Inc.
Prepared Under Contract No. 68-01-3289
U.I
C3
ROBERT K. BASTIAIM, PROJECT OFFICER
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF WATER PROGRAM OPERATIONS
WASHINGTON, D.C. 20460
MCD-36
-------
FOREWORD
This report was prepared for the Municipal Construction
Division of the Environmental Protection Agency as fulfillment of
Task Order No. 9 dated August 3, 1976 under continuing Contract
No. 68-01-3289 dated June 26, 1975. It reviews current practices
in managing the sludge produced at certain municipal wastewater
treatment plants.
-------
SUMMARY
This report describes the sludge handling practices employed
by members of the Association of Metropolitan Sewerage Agencies (AMSA).
Dewatering and disposal methods are evaluated with respect to the preva-
lence of various types of equipment and systems, sludge handling costs,
and other factors. Research needs and nontechnical aspects of sludge
management are discussed.
Composite flow charts are presented to illustrate how the
different plants process sewage sludge. Charts are included for primary,
secondary, and combined sludges. The quantities of sludge handled by
each unit operation and the number of plants using the process are
shown. The most commonly used types of equipment in decreasing order of
frequency, are anaerobic digestion, gravity thickening, and vacuum
filtration. Data on specific types of equipment were correlated with
the type of sludge processed, plant size, and other parameters.
Data on sludge handling costs were analyzed. Only limited
correlations could be made between types of equipment and costs because
most of the data were for the entire sludge handling system and were not
itemized by type of equipment. System costs were difficult to compare
because of the different cost accounting procedures used by the agencies.
Most personnel believe additional research and demonstration
projects will be helpful in improving sludge handling practices. Many
indicated a need for more information on ultimate disposal techniques
and their effects. Ultimate disposal is now the foremost concern for
many administrators because legal constraints have eliminated ocean
disposal and, in some cases, incineration.
XI
-------
TABLE OF CONTENTS
Foreword i
Summary ii
Table of Contents iii
I INTRODUCTION 1
II DATA EASE 4
A. PLANT SIZE DISTRIBUTION 5
B. SLUDGE QUANTITATIVE AND QUALITATIVE INFORMATION 5
C. SLUDGE PROCESS INFORMATION 8
D. OPERATING COSTS AND ENERGY CONSIDERATIONS 8
E. RESEARCH AND DEMONSTRATION ACTIVITIES 9
III PROCESS INFORMATION ANALYSIS 10
A. PRIMARY SLUDGE HANDLING PROCESSES 11
B. SECONDARY SLUDGE HANDLING PROCESSES 17
C. COMBINED SLUDGE PROCESSES 21
IV ANALYSIS OF TYPES OF EQUIPMENT AND DISPOSAL
INFORMATION 27
A. ANAEROBIC DIGESTION 28
B. VACUUM FILTRATION 29
C. CENTRIFUGES 29
D. INCINERATION 30
E. OTHER EQUIPMENT 30
F. TRANSPORTATION INFORMATION 30
G. DISPOSAL METHODS 31
V COST DATA ANALYSIS 33
VI RESEARCH AND DEMONSTRATION NEEDS 35
VII NON-TECHNICAL INFORMATION 37
APPENDIX A - List of AMSA Members Participating
in the Study 39
APPENDIX B - Sludge Processing Methods at
Participating AMSA Plants 43
111
-------
TABLES
I Frequency of Data Availability 6
II Plant Size Distribution by Average Daily Flow 6
III Sludge Quality Data Availability 7
IV Primary Sludge Processing Methods 14
V Secondary Sludge Processing Methods 20
VI Combined Sludge Processing Methods 25
VII Equipment Summary 27
VIII Disposal Method Distribution 31
FIGURES
1. Location of Participating AMSA Members 2
2. Use of Processes for Primary Sludge Management 12
3. Distribution of Flow, Primary Plants 13
4. Distribution of Sludge Processed, Primary Plants 13
5. Distribution of Primary Sludge Processed by
Digestion 16
6. Use of Processes for Secondary Sludge Management 18
7. Distribution of Flow, Secondary Plants 19
8. Distribution of Sludge Processed, Secondary Plants 19
9. Distribution of Flow, Combined Plants 22
10. Distribution of Sludge Processed, Combined Plants 22
11. Use of Processes for Combined Sludge Management 24
12. Distribution of Combined Sludge Processed by
Digestion 26
IV
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I INTRODUCTION
Sludge management has become the center of attention in the'
wastewater treatment industry. In examining the operation of many
treatment plants, sludge management is often found to command a major
portion of the budget, whether it be for capital, labor, materials, or
energy. The problem of economical sludge management becomes more
pressing as the 1977 and 1983 deadlines for more thorough wastewater
treatment approach; in many cases bringing with them voluminous quantities
of the most difficult of the sludges to dewater secondary waste activated
sludge. The sludge management problem is becoming more complicated as
some of the more economical and conventional practices such as ocean
disposal and incineration become environmentally unacceptable.
The Environmental Protection Agency (EPA) is preparing techni-
cal bulletins and reports to assist design engineers and wastewater
authorities in selecting and operating sludge handling systems. These
documents will supplement existing federal guidelines for municipal
wastewater sludge handling. The present study was undertaken to develop
background information on municipal sludge management practices by major
cities for use in preparing the technical bulletins. The basic data for
this report were collected by the Association of Metropolitan Sewerage
Agencies (AMSA) from its members.
AMSA members are responsible for treating a significant portion
of the municipal wastewater in the United States. Usable data were
obtained from 46 of the 54 member agencies, and included 98 plants serving
a total population of over 54 million people, or roughly one-third of
the sewered population of the United States. The Appendix lists those
AMSA members and plants participating in the study. The treatment
plants are located throughout the country as shown in Figure 1, but
nearly 50 percent of the flow treated occurs in the heavily populated
areas of the East and West coasts.
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POPULATION SERVED
2-6 MILLION
A 1-2 MILLION
500,000^
(MILLION
60,000-
500,000
FIGURE 1
LOCATION OF PARTICIPATING AMSA MEMBERS
-------
Current sludge dewatering and disposal practices, costs, and
the non-technical aspects of sludge handling are discussed in this
report. Substantial information was available on process flow schemes
and quantities of sludge dewatered, but only limited data were available
on the details of each type of equipment, costs, sludge characteristics,
and the nontechnical aspects of sludge disposal. With a few exceptions,
efforts to correlate the handling methods with such factors as sludge
"type, plant size, geographical location, and climate were not successful.
Chapter II discusses the data base in more detail. The sludge
dewatering systems used by this segment of the industry are summarized
in Chapter III and individual types of equipment are discussed in Chapter
IV. Chapter V summarizes what cost information was available and Chapter
VI discusses the research and demonstration needs reported by the respondents.
Chapter VII is a summary of the non-technical data collected.
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II DATA BASE
The data used in this report were collected by AMSA from its
members throughout the United States. The data and results were summarized
in an AMSA report entitled "Field Report on Current .Practices and Problems
of Sludge Management" dated June 1976. The report, and in some cases,
follow-up telephone calls were the basis for this evaluation report.
AMSA membership is well distributed across the country; however,
in terms of population served, the east and west coastal areas predominate.
Many of the largest plants in the country are operated by AMSA members.
The majority of members control more than one plant.
Fifty of the 54 members provided some data, but only 46 provided
enough data to be useable in preparing Chapters III and IV. In some
cases a great deal of information was supplied, but others could give
only limited information. Many members had a great deal of information
for each of the plants under their control. Other authorities had
information for selected plants only or the information from several
plants was combined in such a way that it was difficult to attribute
characteristics or processes to individual plants.
Of the 250 plants operated by AMSA members, no data were
available from 67 plants and only very limited data were available from
85 plants. Sufficient information about 98 plants was available for the
preparation of the flow charts in Chapter III. The sample group included
a wide range of treatment processes, from virtually no treatment to
tertiary treatment with chemical precipitation. It was apparent that
many agencies are currently upgrading their treatment plants in order to
meet the requirements of PL 92-500.
1. More detailed information may be obtained by contacting AMSA,
1015 18th Street, NW, Washington, DC 20036
-------
Table I indicates the relative quantities and types of data
available within the original data base. In some cases combined plant
data were separated by cross referencing the data with other information.
In other cases, the information was used if the multiple source character
of the data did not interfere with the nature of the analysis.
A. PLANT SIZE DISTRIBUTION
Plant sizes range from 15 cu m/day (4,000 gpd) to over 3,000,000
cu m/day (800 MGD), and provide a wide sampling of plant types. Table
II shows the size distribution of plants covered in the AMSA study.
B. SLUDGE QUANTITATIVE AND QUALITATIVE INFORMATION
Most agencies had information on sludge weight and volume
readily available. Forty-eight reported quantitative sludge data on a
weight basis, 40 on a volume basis, and 41 specifically indicated the
percent solids content of the sludges. The weight basis for sludge
quantities appeared to be more consistent than volume and was chosen as
the basis for the further analyses in Chapters III and IV of this report.
Qualitative information on the sludges such as nitrogen,
phosphorus, potassium, metals, trace organics, and biological indicators
was not presented in a readily usable form. However, it is apparent
that a number of agencies have substantial quantities of this type of
data. One obvious difficulty in obtaining such information is that many
plants simply do not routinely analyze for these parameters, if at all.
Many take only infrequent grab samples. At other plants, frequent
analyses are required for land application programs. Some plants neglected
to identify the nature of the reported data as for single grabs, average
monthly grabs, or average quarterly grabs, and the units used in reporting
some of the data were unclear. Table III shows the data availability.
-------
TABLE I
FREQUENCY OF DATA AVAILABILITY
Data Available
Few parameters
Number of
Agencies
14
Number of
Plants Controlled
52
Combined data for
multi-plant agencies
12
47
Data for selected plants
only
Data for each plant
TOTAL
5
19
50
29
55_
183
TABL; TI
PLANT SIZE DISTRIBUTION bY AVERAGE DAILY FLOW
Flow
Cu m/day
Under 5,000
5,000 - 30,000
30,000 - 100,000
100,000 - 500,000
500,000 - 3,200,000
MGD
Under 1.3
1.3 - 7.8
7.8-26
26 - 132
132 - 8^7
No. of Plants
36
42
36
44
18
-------
TABLE III
SLUDGE QUALITY DATA AVAILABILITY
Number of
Parameter Agencies
Sludge Weight 48
% Volatile 41
Sludge Volume 40
Zinc (Zn) 33
Cadmium (Cd) 33
Copper (Cu) 31
Lead (Pb) 31
Chromium (Cr) 30
Mercury (Hg) 24
Nitrogen (N) 20
Phosphorus (P) 16
Arsenic (As) 14
Potassium (K) 11
Fecal Coliform 11
Total Coliform 10
Selenium (Se) 9
Boron (B) 6
PCB 5
DDT 5
Dieldrin 5
Salmonella 5
Parasite Ova 4
Chlorodane 4
Virus 2
-------
C. SLUDGE PROCESS INFORMATION
Information was provided on the equipment used to process and
dispose of sludge, as well as the sludge quantities processed by each
type of equipment. The processes were categorized as thickening, stabiliza-
tion, dewatering, and disposal/utilization. This classification worked
reasonably well with a few exceptions. A major difficulty was that some
agencies combined their information from different plants, making it
unclear as to which processes were used in which plants.
Quantitative information was not always supplied, especially
for sludge going to final disposal. In some cases, follow-up telephone
calls were made to supplement and clarify the processing and disposal
information. This information is presented in Chapters III and TV.
D. OPERATING COSTS AND ENERGY CONSIDERATIONS
Some information was also given on the capital, labor, materials,
and energy costs for sludge processing, transportation, and disposal/
utilization. Although costs are the most important aspect of any
process comparison, the scope of the data did not provide much useful
information for cost analysis. One of the major difficulties in analy-
zing sludge processing costs among a range of plants is that many agencies
cannot effectively separate sludge handling costs from the other treatment
costs. This is particularly so for labor and energy costs. In addition,
there is no standard cost accounting procedure that ensures that any two
authorities include the same items within any one cost category. The
result is that a wide distribution of costs were reported, when adjusted
to a per-ton-of-sludge-processed basis. Without background information
to explain the wide variations (most likely because of different accounting
procedures), few correlations could be drawn. The evaluation of this
data is discussed in Chapter V.
-------
E. RESEARCH AND DEMONSTRATION ACTIVITIES
A listing of possible research and demonstration efforts was
made to show both the types of information available to AMSA members and
types of information needed.
Some information was provided on research and demonstration
projects being conducted by the AMSA members along with a listing of
areas requiring additional studies. The greatest area of research and
demonstration needs was the subject of health effects of sludge management,
and cost effectiveness studies. Other areas of needed information
related to energy conservation and market surveys for sludge treatment
by-products. Chapters VI and VII discuss this part of the study.
-------
Ill PROCESS INFORMATION ANALYSIS
One of the principal goals of this project was to analyze the
methods used by AMSA members for processing and disposing of wastewater
sludges. This chapter describes the processes used, the plant sizes,
and the sludge quantity handled by each method.
Present sludge quantities and data from plants now on-line
were used in the discussions in ,this chapter. The anticipated sludge
production from plants-presently under ..construction or in start-up was
not used. Where:-the information was not available, it was-necessary to
estimate some^of. the ,sludge quantities in the treatment plant flow
scheme. .This was restricted to cases in which the sludge quantity was
unknown following or preceeding digestion processes. In no case was
sludge production estimated on wastewater flow. The estimated percent
reduction through digestion processes was based upon other plants in the
data group which reported solids quantities before and after digestion.
Estimates of solids reductions through incineration processes were not
attempted since this figure varies widely.
The 98 plants for which usable data were available were placed
into one or two of three classifications, as follows:
1. Plants processing primary sludge (PRIMARY)
This category includes 40 plants that process only
primary sludge and one plant that processes primary
sludge independent of secondary sludge (also included in
the secondary category)
2. Plants processing secondary sludge (SECONDARY)
Of the 21 plants in this category 14 preprocess secondary
sludge before combining with primary for further dewatering
(also included in the combined category) 6 plants process
only secondary sludge, and 1 plant processes secondary
sludge independent of primary sludge (also included in
the primary category)
10
-------
3. Plants processing a mixture of primary and secondary
sludge (COMBINED)
This category includes 51 plants with 37 mixing primary
and secondary sludge before processing and 14 plants
preprocessing secondary sludge before combining with
primary for final processing (also included in the
secondary category). One of the 51 plants also receives
a small amount of chemical sludge from a water treatment
plant.
The terms Primary, Secondary, and Combined will be used in
this Chapter to describe the process flows in the 98 plants. This
distinction between plant types allowed the development of Figures 2, 6,
and 11, which graphically show the use of the different types of equip-
ment for handling the different types of sludge. None of the plants
handles inorganic sludge from chemical physical treatment. The amount
of sludge processed by each method is partially indicated by the size of
the process representations included on the Figures. The number of
plants using each flow line are also included on these diagrams. Since
some plants truck partially processed sludge to other plants, or use
more than one method to process sludge, the number of plants may change
along a process branch line.
A. PRIMARY SLUDGE HANDLING PROCESSES
Forty-one plants process primary sludge only or process it
separately from secondary sludge. These are shown in Figure 2. The
plants range in size from 295 cu m/day (0.078 mgd) to over 3 x 10 cu
m/day (800 mgd). The total average wastewater flow treated by this
group is 12.3 x 10 cu m/day (3,260 mgd). The reported quantities of
raw primary sludge processed daily ranges from 0.01 to 364 kkg/day (0.01
to 400 dtd), totaling 2048 kkg/day (2,260 dtd). This represents over
160 mg/1 of suspended solids removed from the flow of 12.3 x 10 cu
m/day (3,260 mgd). Figures 3 and 4 show the distribution by size and
the sludge production distribution within this category.
Table IV is a condensation of much of the information in
Figure 2 which tabulates the dewatering methods used and indicates the
11
-------
before land filling
FIGURE 2
USE OF PROCESSES FOR
PRIMARY SLUDGE MANAGEMENT
-------
FIGURE 3
DISTRIBUTION OF FLOW, cu m/day (mgd), FOR PRIMARY PLANTS
\-
z
I
D.
U. 6
o
CC
LLJ
CO
z
^
i
i
4
I
1
7
2
I
\\N
\^
i
1
i
6
3
i
^
i
i
§
\\^
^
^
i
1
4
1
1
(thousands) 0'5 5'20 2°-50 50-100 100-200 200-500 500-1000 over 1.000
MGD (0-1 3) (1 3-5.3) (5.
3-13.2) (13-26) (26-53) (53-132) (132-264) (over 264)
FIGURE 4
DISTRIBUTION OF SLUDGE PROCESSED PER DAY kkg/day (dt/d)
FOR PRIMARY PLANTS
CO
H-
Z
<
-I
0.
LL
O
CC
LU
CO
KKG 0-1
TONS (0-1 1;
I
1
1
1-5
(1 1-5.5)
I
5-10 10-25
(5.5-11) (11-27)
25-50
(27-55)
I
I
I
50-100 100-200 200 up
(55-110) (110-220) (220 up)
15
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TABLE IV
PRIMARY SLUDGE PROCESSING METHODS
A.
B.
C.
No. of
Plants $*
Anaerobic Digestion
1.
2.
3.
4.
5.
Gravity
1.
2.
3.
Drying Beds
Vacuum Filtration
a. Disposal
b . Incineration
Lagoons
Centrifuge
Ocean
Thickening
Anaerobic Digestion
a. Vacuum Filters
Disposal
Incineration
b . Lagoons
c . Centrifuge
d. Ocean
e. Drying Beds
Ocean
Vacuum Filters -
Incineration
Vacuum Filters
1.
2.
Incineration
Disposal
22**
7
6
4
2
4
1
1
14
11***
4
3
1
3
2
2
1
2
1
4
3
1
54
17
15
10
5
10
2
2
34
27
10
7
2
7
5
5
2
5
2
10
7
2
kkg/day dtd $*
534
5
66
47
19
8
227
18
1367
1155
178
38
140
229
98
63
209
164
48
143
142
1
589
6
73
52
21
9
250
20
1507
1273
196
42
154
252
108
69
230
180
53
157
156
1
26
1
3
2
1
1
11
1
67
56
9
2
7
11
5
3
10
8
2
7
7
1
D. Ocean Discharge 1144
* As a percentage of primary plants or primary sludge
** Three plants truck anaerobically digested sludge to a fourth
plant for vacuum filtering
*** One plant uses both vacuum filters and centrifuges to dewater
anaerobically digested sludge
16
-------
popularity of each flow scheme. Figure 2 and Table IV both show the
popularity of gravity thickening and anaerobic digestion for primary
sludges, but no particular preference was evident for a dewatering
method. Vacuum filters, centrifuges, drying beds, and lagoons take
similar quantities of primary sludge. Of the four categories, the
largest dry weight quantity of sludge is dewatered by centrifuge, but at
only three plants. This indicates a greater use of centrifuges among
larger plants. Three plants truck anaerobically digested sludge to a
fourth plant for vacuum filtering and one plant uses both vacuum filters
and centrifuges before landfilling.
The most direct handling method found in this group is ocean
disposal of raw primary sludge. Of three plants discharging raw sludge,
two use gravity thickeners to reduce the sludge volume prior to barging
and the other plant barges less than 4 kkg/day (4 dtd) without prior
thickening. All three plants are located in the New York area.
Within the primary sludge group, sludge that is neither anaero-
bically digested nor discharged raw to the ocean is dewatered using
vacuum filters. Five plants process 191 kkg/day (211 dtd) in this
manner. Only one such installation uses a separate gravity thickener
before filtration. Four of the five plants use incineration after
vacuum filtration to reduce the bulk before landfilling, in some cases
preceded by interim ash lagooning. All five of these plants are located
in large midwestern cities, four of which have populations of over
300,000.
Anaerobic digestion, the process most frequently used to
handle primary sludge, is used at 33 of the plants. Eighty-two percent
of the separately processed primary sludge is handled in this manner.
Figure 5 illustrates the distribution of these plants by size. The
average total solids reduction through this process is 35 percent for
those plants reporting solids values both into and out of their digesters.
Gravity thickeners are used to reduce the volumetric load to some of the
digesters, most notably those at larger installations as seen in Figure 5.
17
-------
FIGURES
DISTRIBUTION OF SLUDGE PROCESSED PER DAY, kkg/day (dt/d) FOR
PRIMARY SLUDGES PROCESSED BY ANAEROBIC DIGESTERS
INDICATES
PRE-THICKENED
BY GRAVITY
!
0.
LL
n
NUMBER (
44 4
3
1
3
I
W////////A
2
§3
KKG 0-1 1-5 5-10 10-25 25-50 50-100 100-200 200 up
TONS (0-11) (1.1-5.5) (5.5-11) (11-27) (27-55) (55-110) (110-220) (220 up)
18
-------
Many different processes were reported for dewatering anaerobi-
cly digested sludge before disposal or use. Within the sampled group,
plant size could not be correlated with a preference for dewatering
method, except that many of the smaller plants use drying beds. Vacuum
filters are used at 10 plants, with three of these incinerating the
resultant filter cake. The other plants truck the dewatered cake to
landfill. Seven of the plants store the stabilized sludge in lagoons
either temporarily or indefinitely. Those plants that must periodically
remove this sludge do so to land, landfill, or ocean disposal. Three
Atlantic Coast plants barge or use a pipeline to move anaerobically
digested sludge directly to ocean disposal.
B. SECONDARY SLUDGE HANDLING PROCESSES
Those plants processing secondary sludge alone or preprocessing
it before combining it with primary sludge are in the secondary plant
category. Twenty-one of the sample group of 98 plants belong to this
category. Figure 6 illustrates the processes, and Figures 7 and 8
relate the distribution of size and sludge production among these plants.
One plant processes secondary sludge independently from the primary
sludge, and six are contact stabilization plants, with only secondary
sludge. The average daily flows within this category ranged from 6400
cu m/day (1.7 mgd) to 3.2 x 10 cu m/day (8-47 mgd) with a total flow of
7 x 10 cu m/day (1866 mgd) among all 21 plants. The quantity of secondary
sludge processed at each plant ranged from 0.39 kkg/day (0.43 dtd) to
164 kkg/day (181 dtd) for a total of 648 kkg/day (714 dtd) for all of
the plants. This total figure represents over 90 mg/1 of secondary
sludge removed from the wastewater treated.
The manner in which secondary sludges are processed varies
widely. For this reason, it was difficult to arrange the flow diagram
for these plants around a few central processes. Instead, Figure 6 has
been arranged around that process by which the secondary sludge is first
handled. Table V is a summary of the information contained in Figure 6.
19
-------
MIXED WITH PRIMARY
'NOTE One plant uses bolh
dissolved air dotation
secondary sludge dewalenng
USE OF PROCESSES FOR
SECONDARY SLUDGE MANAGEMENT
-------
FIGURE?
DISTRIBUTION OF FLOW, cu m/day (mgd) , FOR SECONDARY PLANTS
I-
z
o
CC
LLJ
CD
1
cu m/day
(thousands) °"5 5"20 20-50 50-100 100-200 200-500 500-1.000 over 1.000
MGD (0-13) (13-53) (53-13) (13-26) (26-53) (53-132) (132-264) (over 264)
FIGURES
DISTRIBUTION OF SECONDARY SLUDGE PROCESSED PER DAY,
kkg/day (dt/d), FOR SECONDARY PLANTS
1-
z
Q.
LL
0
CC
LU
QQ 2
3 kx\
Z RV
KKG °-1
7
1
1
1
VX
1
\X
\V
^
5
1
t^l
i
vv
1
XV
XV
^
3
i
1 VV
p_n__ V\
^ ^
1-5 5-10 10-25 25-50 50-100 10
TONS (0-1.1) (1.1-55) (5.5-11) (11-27) (27-55) (55-110) (11
23
-------
TABLE V
SECONDARY SLUDGE PROCESSING METHODS
No. of
Plants %* kkg/day dtd %*
A. Gravity Thickening 8 38 329 363 51
1. Anaerobic digestion 5 24 143 158 22
2. Vacuum Filter-Dryer-Sale 1 5 172 190 27
3. Mixed With Primary 1 5 14 15 2
4. Aerobic Dig.-Mixed
w/Primary 1 5 n.a. - -
B. Dissolved Air Flotation 8** 38 241 266 37
1. Mixed With Primary 6 29 63 69 10
2. Vacuum Filter-Dryer-Sale 1 5 163 ISO 25
3. Aerobic Dig.-Mixed
w/Primary 1 5 14 15 2
C. Centrifuge 4** 19 76 84 12
1. Mixed With Primary 3 14 22 24 3
2. Heat Treatment -
Vacuum Filter 1 5 54 60 8
D. Aerobic Digestion 2 10 2 21
* As a percentage of secondary plants or secondary sludge
** One plant uses dissolved air flotation and centrifugation for the
first step in secondary sludge dewatering
-------
The greater use of thickening processes before dewatering or
stabilization in this category reflects the more dilute nature of secon-
dary sludges. Four plants use centrifuges to thicken secondary sludge
before combining it with primary sludge or further dewatering the
sludge. Dissolved air flotation is also used as a preliminary thickening
process. Six of the eight plants using flotation mix the thickened
secondary sludge with primary sludge following flotation. One large
municipality uses a vacuum filter to dewater flotation thickened sludge,
dryers to further dewater the cake, and then sells the dried material.
Gravity thickeners are used by eight plants, most frequently before
anaerobic digestion for contact stabilization sludges. In a process
arrangement similar to the one mentioned above, gravity thickening is
used rather than dissolved air flotation, followed by vacuum filtration,
drying, and sale as fertilizer/soil conditioner. One plant uses both
dissolved air flotation and centrifugation for the first stop in secondary
sludge dewatering.
C. COMBINED SLUDGE PROCESSING
The majority of the plants within the sample group have both
primary and secondary sludges to dispose of, and combine the two at some
point within their processing scheme. Fifty-one plants fit this category,
ranging in average daily flow from 3,800 cu m/day (1.0 mgd) to 1.32 x
10 cu m/day (3<+8 mgd), and treat a total average daily flow of 10.7 x
10 cu m/day (2,831 mgd). Raw sludge production ranges from 0.5 to 250
kkg/day (0.5 to 274 dtd), totaling 1972 kkg/day (2,174 dtd) for all 51
of these plants. This represents an average removal of over 180 mg/1 of
sludge solids for these plants. Distributions by plant size and sludge
production are shown in Figures 9 and 10.
-------
FIGURE 9
DISTRIBUTION OF FLOW, cu m/day (mgd), FOR COMBINED PLANTS
CO
I-
z
o
CC
UJ
CO
cu m/day
(thousands) °"5
MGD (0-1 3)
5
5-20 20-50
(1.3-53) (53-13)
10
50-100
(13-26)
100-200
(26-53)
11
8
1
200-500 t>00-1000 over 1 000
(53-132) (132-264) (over 264)
FIGURE 10
DISTRIBUTION OF SLUDGE PROCESSED PER DAY, kkg/day (dt/d)
FOR COMBINED PLANTS,
10
10
CO
0.
LL
O
cc
UJ
m
KKG °'1
TONS (0-1 1
8
1-5
(1 1-5 5)
5-10
(5 5-1 11
10-25
(11-27)
3
6
25-50 50-100 100-200 over 200
(27-55) (55-110) (110-220) (over 2201
26
-------
As with uncombined primary sludge, the most common process
within the combined category is anaerobic digestion as shown in Figure
11 and Table VI. A total of 35 plants digest 1,374 kkg/day (1,515 dtd)
of combined sludges. Figure 12 shows a size distribution of plants
processing combined sludges by anaerobic digestion based on the dry tons
per day digested. Gravity thickening preceded digestion in more than
half of these plants indicating a preference among larger plants for
using separate gravity thickeners for combined sludge. The total solids
reduction for plants reporting influent and effluent solids from the
digesters was 40 percent.
As shown on Figure 11, many methods are used to dewater and
dispose of anaerobically digested combined sludges. Five installations
reported using centrifuges before land application, landfilling, or
composting the dewatered sludge. An equal number of plants use vacuum
filters, and one plant incinerates the filtered cake. Fourteen plants
use lagoons or drying beds to concentrate a total of almost 300 kkg/day
(331 dtd) before landfill or land application. Three of the smaller
plants use land application as a means of directly disposing of such
digested sludge. Five intermediate and one very large plant use barges
or pipelines to discharge these stabilized sludges directly to the
ocean. Two plants truck anaerobically digested sludge to other plants
for dewatering.
Vacuum filtration is the second most commonly used process to
handle raw combined sludges. Four of the thirteen plants that handle
sludge in this manner use gravity thickeners to increase feed solids to
the vacuum filters. One plant uses flotation thickening followed by
aerobic digestion to increase dewaterability and decrease the loading on
the filters. Of the thirteen plants using vacuum filters, twelve incin-
erate the filter cake, and either lagoon or landfill the resultant ash.
Two plants use centrifuges to dewater raw combined sludges.
Both of these plants use gravity thickening before centrifuging, then
incinerate the centrifuged cake.
27
-------
NOTE Two planls truck anaerobically digested sludge lo other plants lor
USE OF PROCESSES FOR
COMBINED SLUDGE MANAGEMENT
-------
A.
B.
C.
D.
TABLE VI
COMBINED SLUDGE PROCESSING METHODS
Grav:
1.
2.
3.
4.
No, of
Plants %*
Ity Thickening
Anaerobic Digestion
a . Lagoons
b. Disposal
c. Vacuum Filter
Disposal
Incineration
d. Drying Beds
e. Heat Treat. -Centrifuge
Vacuum Filters
a. Incineration
b. Disposal
Centrifuges-Incineration
Ocean
Anaerobic Digestion
1.
2.
3.
4.
5.
Disposal
Centrifuge
Lagoons
Vacuum Filters
Drying Beds
Vacuum Filters
1.
2.
Incineration
Disposal
25
18
6
5
3
2
1
3
1
4***
4
1
2
1
17**
4
4
3
2
2
8
7
1
49
35
12
10
6
4
2
6
2
8
8
2
4
2
33
8
8
6
4
4
16
14
2
kkg/day dtd %*
965
803
208
59
78
67
11
37
109
122
112
9
13
28
571
166
17
49
93
3
383
288
94
1064
885
229
66
86
74
12
41
120
135
123
10
14
31
630
183
19
54
103
3
422
318
104
49
41
11
3
4
3
1
2
6
6
6
1
1
1
29
8
1
2
5
1
19
15
5
Flotation - Aerobic Digestion-
Vacuum Filters -
Incinceration
1
2
54
60
3
*#*
As a percentage of combined plants or combined sludges
Two plants truck anaerobically digested sludge to other plants
for further dewatering: one to vacuum filtration followed by
incineration and the other to a plant not shown.
One plant disposes of sludge by landfilling and incineration
31
-------
FIGURE 12
DISTRIBUTION OF SLUDGE PROCESSED PER DAY, kkg/day (dt/d) FOR
COMBINED SLUDGES PROCESSED BY ANAEROBIC DIGESTERS
1
INDICATES
PRE-THICKENED
BY GRAVITY
o>
z
Q.
LL
O
NUMBER
3
I
4
1
WH
«
5
''//////////,
1
OsN
XVs
4
V/////////A
2
KKG 0-1 1-5 5-10 10-25 25-50 50-100 100-200 over 200
TONS (0-1.1) (11-55) (55-11) (11-27) (27-55) (55-110) (110-220) (over 220)
32
-------
IV ANALYSIS OF TYPES OF EQUIPMENT AND DISPOSAL INFORMATION
The preceding Chapter summarized the information about the
different systems used by AMSA members to process various types of
sludges. This Chapter summarizes the information available on the types
of equipment and disposal methods used within these dewatering systems.
The numbers of plants using each of these unit operations are tabulated
in Table VII. Particular cost items are included if cost data can be
attributed to any particular equipment such as chemical addition costs
for vacuum filtration. A series of telephone contacts made to complete
information for Chapter II was a major source of this information.
TABLE VII EQUIPMENT SUMMARY
No. of
Type of Equipment Plants % of 98 Plants kkg/day (dtd)
Anaerobic digestion 73 74 3,206 (3,535)
Gravity thickening 47 48 2,661 (2,934)
Vacuum filtration 36 37 1,538 (1,695)
Incineration 22 22 812 ( 895)
Lagoons 22 22 567 ( 625)
Centrifuge 14 14 540 ( 595)
Dryers 3 3 340 ( 375)
Dissolved air flotation 9 9 295 ( 325)
Drying beds 13 13 255 ( 281)
Heat treatment 2 2 163 ( 180)
Aerobic digestion 5 5 70 ( 77)
-------
A. ANAEROBIC DIGESTION
Within the sample group, 73 plants use anaerobic digestion for
stabilization and volume reduction of sewage sludge. The breakdown of
sludge types so processed is as follows:
1. Combined - 35 plants
2. Primary - 33 plants
3. Contact stabilization - 5 plants
The total feed of solids was 3206 kkg/day (3535 dtd). The average
solids content of the feed sludge was 5.5 percent, which indicates that
over 58,000 cu m/day (15 mgd) of sludge is anaerobically digested within
this sample group alone.
The personnel of twelve plants using anaerobic digestion
provided detailed information about the operation of their digesters.
The group was evenly divided between single- and multiple-stage digesters.
All use internal gas mixers, and seven use external heat exchangers.
The remainder use steam injection or internal hot water circulation
pipes for heating. The average volatile suspended solids reduction
through the digesters was reported as 50 percent. The detention times
reported ranged from 15 to 65 days, and averaged 30 days. The cleaning
schedules for digesters ranged from none (eight-year old digesters) to
every two to three years. The addition of pretreatment by major industrial
users was cited by some members as a great aid in extending the time
between cleanings.
Of the 73 plants using anaerobic digestion, data on gas
production, utilization, and wastage were available from 52. The quantity
of gas produced per pound of volatile matter destroyed could not be
determined from the data; 152 cu m/kkg (4,880 cu ft/dt) were produced,
however. The total quantity of digester gas produced was indicated as
178 x 10 cu m/yr (6.3 x 10 cu ft/yr). Within the group, the number of
plants practicing digester gas energy recovery is as follows:
-------
Plants reporting 52
Plants recovering energy as:
Usable heat 30
Electricity 12
Mechanical energy 4
One facility with extensive digester operations indicated that over half
of the daily digester gas production is sold. Other agencies indicated
plans to sell digester gas in the future. Two agencies specifically
indicated that digester gas is not wasted.
B. VACUUM FILTRATION
Thirty-six plants use vacuum filters to dewater raw and
digested sludges. Of these plants, 19 process raw sludge, 16 process
digested sludge, and one processes heat treated sludge with vacuum
filters. Twenty incinerate the cake and 17 landfill it or dispose of it
in some other manner. A total of 1538 kkg/day (1,695 dtd) are dewatered
on vacuum filters within this group.
Information on the common operational characteristics of
vacuum filters was provided by 16 plants. Within this group, eight
plants are equipped with belt type filters, and an equal number have
coil spring media filters. A preference for either type for either raw
or digested sludge was not apparent. The average solids content for raw
sludge cake was 29 percent. Digested sludges yielded a wetter cake with
21 percent solids. Very few of the plants had cost figures attributable
directly to the vacuum filters; however, chemical conditioners were
quoted as costing $4 to $19 per kkg processed ($4 to $17 per dt). Six
plants rely solely on polymer conditioners, three on lime and ferric
chloride, and three reported using a combination of all three chemicals.
Personnel at one plant stated that polymer works well in winter months,
but becomes very difficult to control in the warmer months.
C. CENTRIFUGES
Fourteen plants use centrifuges for dewatering or thickening,
eight for digested and six for raw sludges. Most of the centrifuges are
35
-------
the solid bowl type, except for two plants that use disc-nozzle type
machines. Both authorities using the disc-nozzle centrifuges reported
concentration to 4 to 4.5 percent solids with waste activated sludge.
Nozzle wear and plugging were cited as difficulties with the machines,
and one plant noted that fines buildup was a potential problem.
Seven plants centrifuging primary sludge provided information
on solid bowl centrifuge operations. The average cake dryness was 22
percent, with feed solids averaging 5.7 percent. Four of these plants
use polymers, with costs averaging $13 per kkg ($12 per dt) for the
three which had costs available. Most of the authorities were pleased
with their centrifuges, but stated that maintenance was a high cost item
for the process.
D. INCINERATION
Twenty-two plants incinerate 812 kkg/day (853 dtd) of primary
and combined sludge solids. The resultant ash quantities were not
reported in many cases. Twenty of the plants use vacuum filters before
incineration, with two using centrifuges. Only four plants incinerate
anaerobically digested sludge.
E. OTHER TYPES OF EQUIPMENT
Few process or operating details were available for the other
sludge handling methods and equipment, such as heat treatment and dryers.
As would be expected, there is little operational information available
for simpler operations such as lagooning and sand bed drying.
F. TRANSPORATION INFORMATION
A broad base of information on transporting processed sludge
was not available for analysis. Of those agencies reporting, trucking
to disposal was the most commonly reported transportation method.
Pipelines are also used by several agencies, but little additional
information was available on costs or operational characteristics.
36
-------
G. DISPOSAL METHODS
The disposal methods used by the plants discussed in Chapter
III are summarized in Table VIII. The chart reflects the limited applicabilit
of certain disposal/utilization methods and the versatility of others
with respect to the sludge solids content. Whereas landfill is used to
dispose of liquid sludge, dewatered sludge and ash, sale or giveaway
programs must produce a dry cake. There is, on the other hand, apparently
no advantage for land applying ash, or for ocean dumping dewatered
sludge.
TABLE VIII DISPOSAL METHOD DISTRIBUTION
LIQUID DEWATERED
Plants
Sale & giveaway
Ocean
Landfill*
Land Application*
Lagoons*
Incineration** - 22 812 (895)
* Incinerator ash not included
** Of those plants incinerating sludge, 18 landfill and 4 lagoon the
ash for final disposal.
The range of disposal methods was carefully examined to corre-
late geography and plant size with the method chosen. Definite preferences
could not be discerned, aside from the expected preference of large
coastal cities for ocean disposal.
One significant factor common to all the plants, large and
small, is that many are located in relatively large urban areas, especi-
ally within the dense population centers of the East and West coasts.
Plants kkg/day (dtdj
_
19 756 (833)
2 6(7)
9 228 (251)
7 n.a n.a.
Plants kkg/day (dtd)
8 864 (953)
- - -
25 412 (454)
5 137 (151)
_ _
37
-------
Air emission requirements compatible with the constraints of densely
populated areas, and effective land use planning restrict the available
acceptable methods of disposal in these locations. Many of the agencies
in these areas expressed great concern about the disposal problem, in
many cases because of impending ocean dumping restrictions.
38
-------
V COST DATA ANALYSIS
Limited data were available on the cost of sludge dewatering.
The costs were given for the entire sludge dewatering process and it was
not possible to itemize costs for particular types of equipment. Because
of the many combinations of equipment, only very general correlations
can be drawn between cost items and processing methods. Cost information
development was further complicated by the difficulty most plants have
in determining what part of their budget is attributable to sludge
handling as contrasted with the main flow wastewater treatment costs.
The data were analyzed to reflect the dollar-per-kkg or manhours-per-
kkg costs on a plant by plant basis. In all cases, the costs were
related to raw sludge processed, not to the reduced sludge quantity
following digestion. Although the scatter in the data does not warrant
including it here, general cost trends are discussed below.
Labor costs were examined on a manhours per kkg basis for the
59 plants reporting this data. Information from the participating
plants was carefully examined to determine the more prevalent methods at
the low and high ends of the distribution. Although the data were very
scattered, it was apparent that plants expending less than one mh/kkg
frequently use anaerobic digesters followed by indefinite lagooning or
ocean disposal. The highest mh/kkg plants included a few using anaerobic
digesters and lagooning or ocean disposal, plus a significant number of
the more labor intensive operations such as flotation, incineration, and
vacuum filters. It was apparent that much of the variation in costs
could be attributed to data reporting differences and that the range of
manhour requirements for a given type of equipment would generally have
been less had all of the data been reported on the same basis.
Materials costs were compared on a dollar per kkg of raw
sludge basis. This category includes such items as conditioning chemicals
and spare parts. As with other cost items, it was difficult to draw
conclusions about the relative costs of different individual types
39
-------
of equipment. Forty-five plants reported materials costs. Equipment
requiring high dosages of chemical conditioning agents were prevalent
in the plants with high materials costs. This group includes plants
using centrifuges, flotation units, and vacuum filters.
Electrical costs were reported by 53 plants, and were extremely
variable. Although the data were scattered, the highest figures were
reported for plants that employ one or more of the following: air
flotation, vacuum filtration, centrifugation, and incineration.
-------
VI RESEARCH AND DEMONSTRATION NEEDS
In addition to covering process flows and equipment, 30
authorities indicated the areas they felt were lacking in sludge manage-
ment information. Five general topics were covered: management activi-
ties, socio-political or institutional constraints, public health,
monitoring and surveillance, and disposal alternatives. A. strong interest
was shown in cost effective sludge handling and disposal processes that
will not adversely affect public health. Public health is the most
important factor in many cases.
Only 15 percent of the authorities felt sufficient information
was available on the public health aspects of sludge management. Topics
of particular interest were epidemiological studies, disinfection alterna-
tives, and landfill leachates.
Eighty-five percent of the study group also want more information
related to management activities such as energy conservation efforts,
market surveys for commercial projects, and cost-effectiveness studies
on sludge management.
The majority of the 19 authorities indicating a need in the
socio-political or institutional constraints category felt more information
was needed in the areas dealing with legal constraints, environmental
groups, competition or cooperation from other government groups, and
public acceptance and public meeting response.
A similar indication was seen regarding the issues of monitoring
and surveillance. Although 42 percent indicated that sufficient informa-
tion was available on ocean and estuary monitoring, fewer authorities
felt there was sufficient material available associated with land
disposal, such as surface and groundwater, soil, and crops monitoring.
-------
Over 20 authorities indicated that more information was needed
on disposal alternatives. The greatest need was for information on soil
reclamation, soil enrichment, and composting. Fewer indicated a desire
for more information on ocean disposal, incineration, pyrolysis, and
sludge and solid waste landfill. Only minor interest was expressed in
by-product recovery, co-incineration, the Carver-Greenfield process, and
sale as commercial fertilizer.
In addition to the specific listings discussed above, authorities
listed other information needs. Too numerous for listing here, over 60
needs for research and demonstration projects were listed. Generally,
interest was in the areas of processing and disposal with emphasis on
the health aspects and the effects of land disposal on agriculture and
livestock. Only minor interest was indicated in the areas of utilization
and regulatory requirements.
-------
VII NON-TECHNICAL INFORMATION
Non-technical information was also provided by twenty selected
AMSA members on such issues as energy recovery, disposal problems, land
acquisition for disposal, institutional constraints, funding, public
involvement, health issues, and metals concentrations. The agencies
providing information represented a cross section of the membership
based on size, location, and agency type (city; county, special district,
or state). The most common difficulty reported was establishing a
disposal method that is compatible with existing local, state, and
federal regulations at an acceptable cost.
Many authorities are reluctant or find it impossible to use
land application. This, in most cases, is because of the unavailability
of suitable land within economical transportation distances. Other
related problems are the inability to transport sludge across juris-
dictional lines or other legal problems associated with overland trans-
portation and land disposal. One agency cited the lack of a heavy
metals ordinance as preventing the implementation of land application
programs. Other agencies felt that land application was totally unaccept-
able because heavy metal concentrations could not be acceptably reduced.
The unknown effects of trace materials on groundwater were also viewed
as reason for a cautious approach to land application. Those authorities
in favor of land application (5 of the 20) had been doing so for some
time, either to park areas, golf courses, etc., or to farms. In all of
these cases, the chance of human ingestion was felt to be unlikely for
the particular practices used. Of the group interviewed, only three had
actually purchased land for ultimate disposal.
Several of the agencies oppose incinerating as a means of
sludge disposal. The most frequently cited point of opposition is
-------
the strict air pollution codes that require costly control measures.
One agency felt that incineration was a waste of both fuel and residual
materials that can be used as a valuable resource for soil enrichment.
The twenty selected agencies also commented on public involvement
with sludge management issues. The most common form of public involvement
is complaints about odors around disposal sites or treatment plants.
Although usually limited to specific areas, the resolution of such
problems takes considerable effort. The other form of public involvement
is selecting disposal sites and processes. Such input is usually negative,
in the form of opposition by particular groups which feel they will be
unfairly jeopardized by particular locations. Reduced property values
are a major concern. On the positive side, some environmental groups
encourage the use of processes that they feel are the most environmentally
acceptable, e.g., regulated land application.
In review of the non-technical comments, the most pressing
problem is evidently the ultimate disposal of sludge. As sludge quantities
increase and environmental restrictions become more stringent, the
agencies feel they are often faced with unrealistic deadlines set by
regulatory agencies.
-------
APPENDIX A
LIST OF AMSA MEMBERS
PARTICIPATING IN THE STUDY
-------
SUMMARY CHARACTERISTICS OF AMSA MEMBERS
Agency
Chicago, IL
New York, NY
Philadelphia, PA
Los Angeles County, CA
Boston, MA
Los Angeles City, CA
St. Louis, MO
Cleveland, OH
Passaic Valley, NJ
Baltimore, MD
Milwaukee CO, WI
Allegheny Co, PA
Orange Co, CA
Cincinnati, OH
Miami-Dade Co, FL
Seattle, WA
Denver, CO
Atlanta, GA
Dallas, TX
Columbus, OH
San Diego, CA
ADF
Thousand
cum/ day
5,378
3,846
1,805
1,665
1,654
1,359
1,048
929
924
765
719
681
659
621
568
537
530
519
462
454
424
mgd
1421
1061
477
440
437
359
277
245
244
202
190
180
174
164
150
142
140
137
122
120
112
Raw Sludge
kkg/day
568
260
269
372
122
249
145
211
111
123
263
116
159
162
171
41
94
23
73
n/a
81
(dry).
dt/d
626
287
297
410
135
274
160
233
122
136
290
128
175
179
188
45
104
25
80
n/a
89
Service Population
5,500,000
7,867,760
3,000,000
3,800,000
2,176,000
3,100,000
1,520,000
1,276,000
1,157,215
1,550,000
1,272,000
1,250,000
1,400,000
920,000
1,800,000
1,200,000
1,100,000
850,000
993,400
790,000
1,200,000
Plants
7
12
3
12
2
3
4
3
1
2
2
1
2
4
3
5
1
6
3
2
5
-------
CD
Agency
San Francisco City & Co, CA
Monroe Co, NY
Hampton Roads, VA
Akron, OH
Kansas City, MO
Louisville, KT
Middlesex Co, NJ
Portland, OR
Bergen County, NJ
Oakland (East Bay
M.U. Dist. ), CA
Wayne County, MI
Nashville, TN
Fort Worth, TX
Dayton, OH
Omaha, NE
Hartford Co, CT
Providence, RI
Ventura Regional Co, CA
El Paso, TX
Trinity River, TX
Wichita, KS
Raw Sludge (dry)
Service Population
Plants
Thousand
cum/day
409
379
367
341
337
333
318
314
299
291
280
250
242
208
197
170
170
155
148
144
132
mgd
108
100
97
90
89
88
84
83
79
77
74
66
64
55
52
45
45
41
39
38
35
kkg/day
n/a
46
35
29
48
38
54
82
60
18
82
54
71
38
33
33
54
n/a
15
28
33
dt/d
n/a
51
39
32
53
42
59
90
66
20
90
59
78
42
36
36
60
n/a
17
31
36
700,000
714,000
859,238
377,700
500,000
495,000
600,000
307,000
600,000
625,000
450,000
290,000
606,000
371,000
530,000
283,517
210,000
370,000
376,000
363,000
280,000
3
3
9
1
15
1
1
2
1
1
4
5
2
1
3
4
1
9
4
2
1
-------
Agency
Albany, NY
Tuscon, AZ
Washington, Suburban MD
Duluth (Western Late
Superior Sanitation
Dist.) m
Greensboro, NC
Honolulu, HI
Boise, ID
Charleston, WV
ADF
Raw Sludge (dry)
Thousand
cum/day
132
121
106
79
76
68
38
26
mgd
35
32
28
21
20
18
10
7
klcg/day
22
n/a
33
9
23
11
10
n/a
dt/d
24
n/a
36
10
25
12
11
n/a
250,000
349.000
203,000
116,480
167,000
531,627
64,155
75,000
i rj.tU10t>
2
2
3
9
2
19
3
1
vo
-------
APPENDIX B
SLUDGE PROCESSING METHODS
AT
PARTICIPATING AMSA PLANTS
-------
SLUDGE PROCESSING METHODS
AT
PARTICIPATING AMSA PLANTS
AKRON
ALBANY North
South
ALLEGHENY CO.
ATLANTA South River
Intrenchment
Flint River
Camp Creek
Utoy Creek
BALTIMORE Patapsco
Back River
BERGEN CO.
BOISE Lander Street
BOSTON Deer Island
Nut Island
CHICAGO Calumet
West-SW
CINCINNATI Mill Creek
CLEVELAND Southerly
Westerly
DALLAS Central
DAYTON
DENVER
s
c
s
c
s
c
c
s
c
c
s
c
c
s
c
p
c
p
s
c
p
p
c
p
s
p
c
p
c
c
s
c
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
1
2
1
2
2
2
1
1
2
2
1
1
2
2
2
1
1
1
1
1
2
1
2
3
2
3
2
2
1
2
2
2
2
2
2
2
2
3
3
2
2
2
2
2
4
3
3
2
4
4
3
3
3
3
3
3
3
3
3
3
3
3
4
5
3
3
3
2
4
2
Numbers Indicate Process Order
53
-------
SLUDGE PROCESSING METHODS
AT
PARTICIPATING AMSA PLANTS
DULUTH Main
Fairmont
Cloquet
Smithville
Carlton
Gary New Duluth
Scanlon
EL PASO Haskell Street
FORT WORTH Village Creek
Riverside
GREENSBORO North Buffalo
HARTFORD CO.
HONOLULU Mililani
Wahiawa
Kaneohe
Kailua
Pearl City
KANSAS CITY Blue River
LOS ANGELES CITY Hyperion
LOS ANGELES CO. Joint
District 14
District 20
District 26
District 32
LOUISVILLE
MIAMI-DADECO. Central
p
p
p
p
p
p
p
s
c
s
c
c
c
s
c
c
c
c
c
p
p
c
p
p
p
s
c
s
c
p
c
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
2
1
2
1
1
1
1
1
1
1
1
?
2
2
2
1
2
1
4
2
1
2
1
3
2
2
3
2
3
2
2
2
2
2
3
3
2
2
3
2
2
3
2
4
3
2
3
2
2
2
3
3
3
3
5
2
3
4
2
3
3,4
3
4
3
4
3
3
S
3
4
3
?
?
Numbers Indicate Process Order
-------
SLUDGE PROCESSING METHODS
AT
PARTICIPATING AMSA PLANTS
MIDDLESEX CO.
MILWAUKEE CO. Jones Island
South Shore
MONROE CO. Frank E.Vanlare
Northwest Quadrant
Gates-Chili-Ogden
NASHVILLE Central
NEW YORK CITY 26th Ward
Wards Island
Newtown Creek
Rockaway
Jamaica
Coney Island
Port Richmond
Oakwood Beach
Tallman Island
Bowery Bay
Owls Head
Hunts Point
NORFOLK Chesapeake
Army Base
Lamberts Point
Boat Harbor
James River
Wilhamsburg
Western Branch
Washington
OAKLAND East Bay Munic.
p
s
c
c
c
p
c
c
c
s
s
c
s
p
c
c
c
s
c
s
p
p
p
c
c
p
p
p
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
2
2
2
2
2
2
2
2
2
2
2
1
1
1
2
1
1
1
2
2
2
2
2
3
2
3
2
3
2
3
3
4
3
2
3
2
3
3
3
3
1
3
3
3
3
4
3
4
2
2
3
2
2
4
3
5
4
3
3
3
4
3
4
3
3
Numbers Indicate Process Order
55
-------
SLUDGE PROCESSING METHODS
AT
PARTICIPATING AMSA PLANTS
OMAHA Missouri River
Papillion
ORANGE CO.
PASSAIC VALLEY
PHILADELPHIA Northeast
Southwest
PORTLAND Columbia
Tryon Creek
PROVIDENCE
SAN DIEGO Point Loma
SEATTLE West Point
ST. LOUIS Bissell Point
Lemay
Coldwater
Sugar Creek
TRINITY RIVER Central Region
WASHINGTON SSC Piscataway
Western Branch
Parkway
WAYNE CO. Wyandotte
WICHITA
p
p
p
p
p
p
p
s
c
c
p
p
p
p
c
c
c
p
c
c
c
c
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
1
2
2
1
1
2
2
2
1
3
1
3
2
?
1
3
3
2
3
1
1
3
3
1
2
2
2
3
2
3
2
2
4
3
2
2
4
4
4
3
3
3
3
3
2
3
2
4
3
4
4
4
4
4
4
4
5
4
3
4
Numbers Indicate Process Order
6GPO 1802-328
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