EPA-43 0/9-75-018
SEPTEMBER 1975
TECHNICAL REPORT
WASTEWATER SLUDGE UTILIZATION
AND DISPOSAL COSTS
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Water Program Operations
Washington. D.C. 20460
MCD-12
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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 Environ-
mental Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
NOTES
It is the intention of the Environmental Protection
Agency to revise and update this Technical Report as
more technical information becomes available. The
most valuable source of information for revisions
will be the actual experiences of those using the re-
port. All users are encouraged to submit such infor-
mation to the Director of the Municipal Construction
Division (WH-547), Office of Water Program Operations,
Environmental Protection Agency, Washington, D.C. 20460.
Methods of estimating costs and evaluating the cost-
effectiveness of conventional wastewater treatment
works have been developed in a separate document, en-
titled, A Guide to the Selection of COST-EFFECTIVE
WASTEWATER TREATMENT SYSTEMS, NO. EPA-430/9-75-002,
MCD-11.
Methods of estimating costs and evaluating the cost-
effectiveness of land-application systems have been
developed in a separate document, entitled, Technical
Report, Costs of Wastewater Treatment by Land Appli-
cation, No. EPA 430/9-75-003, MCD-10.
To order publications MCDT10, MCD-11, or MCD-12 write to:
General Services Administration (8-FY)
Centralized Mailing List Services
Bldg. 41, Denver Federal Center
Denver, Colorado 80225
Please indicate the MCD No. and title of publication.
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EPA-430/9-75-015
SEPTEMBER 1975
WASTEWATER SLUDGE UTILIZATION
AND DISPOSAL COSTS
BY
Timothy G. Shea, Ph.D.
John D. Stockton
EPA CONTRACT P5-01-205
Prepared for
Municipal Technology Branch
Municipal Construction Division
Office of Water Program Operations
U.S. Environmental Protection Agency
Washington, D.C. 20460
MCD-12
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ABSTRACT
A flow sheet describing various sludge utilization and disposal
alternatives is presented. Amortized capital and O&M costs are shown
for plant capacities ranging from 1 - 1000 MGD. From this informa-
tion preliminary comparisons of the cost-effectiveness of various sludge
utilization and disposal alternatives can be made. The report pro-
vides supplementary information which when combined with the Technical
Report: A Guide to the Selection of Cost-Effective Wastewater Treat-
ment Systems, EPA-430/9-75-002 and Costs of Wastewater Treatment by
land Application provides construction grant applicants with informa-
tion for preliminary cost comparisons of various wastewater management
alternatives.
ACKNOWLEDGEMENT
This report was prepared by W. E. Gates and Associates, Inc.,
Fairfax, Virginia.
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TABLE OF CONTENTS
Section Page
I INTRODUCTION 1
II DESCRIPTION OF ALTERNATIVES 2
III DEVELOPMENT OF COST RELATIONSHIPS 5
Approach 5
General Cost Estimating Conditions 5
Unit Treatment Processes 6
Transport Methodologies 7
Ultimate Disposal Methodologies 8
Cost Relationships 9
IV SLUDGE DISPOSAL COST CURVES 11
V REFERENCES 12
FIGURES
No.
1 Sludge Disposal Alternatives
2 Sludge Disposal Cost Curves
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SECTION I
INTRODUCTION
The purpose of this report is to present a series of cost relationships
for sludge disposal alternatives and to describe briefly the process and
type of information used in creating the cost relationships. In this context
the term "sludge disposal alternative" is used to connote the combination
of sludge treatment processes and sludge transport and ultimate disposal
methodologies comprising a sludge management system.
The basic premises or conditions selected for development of the cost
curves were as follows:
1. The variables to be considered in the relationships were:
a. Sewage treatment plant flow rates varying from one to 1,000 MGD.
b. Two levels of treatment, primary and (activated sludge) secondary.
c. Sludge treatment processes incorporating incineration and anaerobic
digest ion.
d. Transport to ocean disposal by barging and to land disposal by
truck, rail, and pipeline.
e. Land disposal by landfill and land spreading.
2. The range of transport distances for the ocean barging and land disposal
methodologies were selected to reflect the transport distances likely
to be considered by Eastern Seaboard cities, and were as follows:
a. Barge transport to ocean disposal locations at distances of 15,
50, 80, 110, 150, and 180 miles from the barge loading station.
b. Land transport over distances of 20, 50, 100, and 150 miles.
3- Barging transport costs were to be developed for two situations, viz,
a. "Simple" case, wherein all sludge generated in a metropolitan
area can be loaded at a single barge loading station.
b. "Complex" case, where sludge is collected from a multiplicity
of barge loading stations in a metropolitan area before the
barge can be towed to sea.
4. All cost relationships were to be developed using March 1975 costs.
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SECTION I I
DESCRIPTION OF ALTERNATIVES
The sludge disposal alternatives for which cost relationships were
developed are shown in Figure 1. The basic alternatives are as follows:
1. Alternative I: vacuum filtration of primary and thickened biological
sludges to produce a sludge stream at 20% solids, followed by incineration
and truck haul of the incinerator ash to a landfill site.
2. Alternative II: digestion of primary and thickened biological sludges
followed by barging to an ocean disposal site under "simple" and "complex"
barging conditions as defined in Section I.
3. Alternative III: digestion of primary and thickened biological
sludges, vacuum filtration of a portion of the digested sludge stream
and blending of this portion with undewatered digested sludge to
produce a sludge at \0% solids, followed by barging to an ocean dis-
posal site under "simple" and "complex" barging conditions.
k. Alternative IV: digestion of primary and thickened biological sludge,
followed by tank truck or pipeline transport to a landspreading site.
5. Alternative V: digestion of primary and thickened biological sludge,
followed by vacuum filtration to produce a sludge stream at 20% solids,
and truck or rail transport to a landfill site.
Subalternatives were defined in each alternative to account for sludge
handling and disposal associated with primary and activated sludge secondary
treatment as follows:
1. The secondary treatment suba1ternatives within each alternative were
cost-evaluated as shown in Figure 1 and described above, i.e., inclusive
of the biological sludge stream and the thickening unit process for
this stream.
2. The primary treatment subalternatives were cost-evaluated exclusive
of the biological sludge streayn and the thickening unit process for
this stream.
In developing material balances for the sludge "flow" through the
unit process trains in each alternative, the normalized parameter selected
was "tons of dry solids per day per MGD of flow." The values of this
parameter for the sludge stream at each point in the unit process trains,
and the corresponding solids concentrations of the sludge stream, are shown
in Figure 1. These data were developed using the assumptions that:
1. Primary treatment generates 0.5 ton dry solids/day/MGD at 5% solids
in the sludge flow from the primary clarifiers.
2. Secondary treatment generates 0.5 ton dry solids/day/MGD at 5% solids
in the sludge flow from the primary clarifiers and 0.25 ton dry solids/
day/MGD at 2% solids in the biological sludge flow from the secondary
clarif iers.
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FIGURE 1. SLUDGE DISPOSAL ALTERNATIVES
Primary_ Sludge Biological Sludge
[~0. 25 T
Notes:
1 . Units of "T" are:
Q J0 Tons dry sol ids per
L ° day per MGD of raw
0.5 T @ 5% 1 DAF Thickening] sewage.
•
10.25 T
v M +
0.75 T @ 5%
i t
4
I VAC. FILTRATION! I DIGESTION |
1
0.71 T @ 20% °'1*5 T @ ^
| INCINERATION |
r~ . r .
| PARTIAL VAC. F 1 LT|
0.21 T (Ash) 0.^5 T 1 -W'
@ W Bypass 0.^ T
r @ 10?
| TRUCK | BARGING BARGING TP
| LAN
LI
DFILL | OCEAN DISPOSAL! 1 OCEAN DISPOSAq | LP
1 1 III
@ 5% 2. Units of "I" are:
weight percent dry
sol ids.
i
VAC. FILTRATION)
0.45 T 0.1*3 T
T UCK OR PIPE- TRUCK OR RAIL
NE TRANSPORT TRANSPORT
i ' ^ r
NOSPREAD ING LANDFILL
IV V
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3. Thickening by dissolved air flotation (DAF) increases the solids
concentration in biological sludges from 2 to 5%.
*». Incineration results in destruction of 70% of the dry solids content
of the sludge flow.
5. Digestion (anaerobic) results in destruction of kO% of the dry solids
content of the sludge flow.
6. Dewatering to 20% solids can be achieved with vacuum filtration.
7. The maximum solids concentration of which sludge can be discharged
(pumped) from a barge is 10%.
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SECTION III
DEVELOPMENT OF COST RELATIONSHIPS
APPROACH
X
The steps used in the development of the cost estimates were as follows:
1. Cost data were developed for each unit process, transport method, and
ultimate disposal method specified in the sludge disposal alternatives
presented in Figure 1, taking into consideration the variables of:
a. Plant flow rate (1, 10, 100 and 1,000 mgd).
b. Type of treatment (primary and secondary).
c. Type of transport (truck, rail, pipeline, and barging) and one
way transport distance (land, at 20, 50, 100, and 150 miles; and
ocean, at 15, 50, 80, 110, 150, and 180 miles).
d. Type of barging (simple or complex).
2. The above cost data were used in compiling costs by alternative for
each combination of variables within each alternative, to obtain
the desired sludge disposal alternative cost data; because of the
number of variables considered in each alternative, the sets of cost
data developed in each alternative were as follows:
a. Alternative I - 32
b. Alternative I I- 96
c. Alternative 11 I- 96
d. Alternative IV- 32
e. Alternative V - 32
3- The selection of which transport mode was to be used in Alternatives
IV and V (truck or pipeline in Alternative IV and truck or rail in
Alternative V) was based on least cost.
k. The 288 sets of cost data obtained in the preceding steps were utilized
in the development of a graphical presentation of capital cost and
total annual (amortization plus operation/maintenance) costs as a
function of flow rate, treatment level, transport distance, etc., as
the end product.
The cost relationships developed in Step ^ above are presented and
described in Section IV, and the development of the cost data for the
individual unit treatment processes and transport and ultimate disposal
cost relationships is presented below.
GENERAL COST ESTIMATING CONDITIONS
The cost estimating conditions that were applied generally in the
development and/or updating of cost curves for individual unit treatment
processes and the transport and ultimate disposal methodologies are as
follows:
1. Economic factors:
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2,000
2,500
3,000
3,500
1 ,000
1,500
2,000
2,500
500
1 ,000
1 ,000
1,000
500
1,000
1,000
1 ,000
a. Interest rate - 5 7/8% and project life = 20 years, for which the
value of the Present Worth Factor is 11.59 and the value of the
Capital Recovery Factor is 0.0863.
b. Labor rate (including fringe benefits) = $6.50 per man hour.
c. Service and Interest Factor = 7.1%.
d. STP Index (Environmental Protection Agency) = 232.1 (March 1975).
e. Wholesale Price Index (Department of Commerce) = 170.^ (March 1975)
f. CCI (Engineering News Record) = 2200.
2. Land Unit Costs:
a. Treatment plant sites:
Q(MGD) Land Cost ($/Acre)
1 3,000
10 *4,000
100 5,500
1,000 8,000
b. Landfill or landspreading sites:
Q Land Cost ($/Acre) at Haul Distances of
(MGD) 20 mi . 50 mj_. 100 mi. 150 mi.
1
10
100
1 ,000
3. Sludge generation quantities: the assumption used is that secondary
treatment results in generation of 0.75 ton dry solids/day/MGD, and
primary treatment in 0.5 tons dry solids/day/MGD; thus for any given
flow rate, the sludge quantity generated for primary treatment is
assumed to be equal to two thirds of the quantities generated for
secondary treatment.
The additional assumptions, specific to cost evaluating each unit
process and sludge transport and disposal methodology, are discussed below.
UNIT TREATMENT PROCESSES
Dissolved Air Flotation
Capital, 0/M and total annual costs for the DAF (dissolved air flotation)
thickening of biological sludges were estimated using cost relationships
developed by McMichael (Reference l), updated to March 1975- The para-
meters used in developing the DAF cost data were as follows:
1. Dry solids loading rate of kB Ib/day/sq ft.
2. Polymer dose at 10 Ib/ton dry solids and polymer cost at $1 per Ib.
Vacuum Fi1trat ion
Estimates of capital, 0/M, and total annual costs for the vacuum
filtration process were developed using the following Bechtel cost rela-
tionships, updated to March 1975:
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1. Alternative I: vacuum filtration of raw primary and biological sludge
(Reference 2).
2. Alternatives II and V: vacuum filtration of digested primary and
biological sludge (Reference 3).
Incinerat ion
Estimates of capital, 0/M, and total annual costs for the incineration
process were developed using Bechtel cost relationships (Reference k),
updated to March 1975-
Digestion
Estimates of capital, 0/M, and total annual costs for the anaerobic
digestion process were developed using Bechtel cost relationships (Re-
ference 5), updated to March 1975-
TRANSPORT METHODOLOGIES
P i peli ne
Estimates of capital, 0/M, and total annual costs for pipeline trans-
port of sludge slurries were developed using cost relationships presented
by Thompson e_t^ a_l_ (Reference 6), updated to March 1975- The updated
cost relationships were applied using the assumptions that:
1. "Downtown" construction cost curves apply for pipeline installations
from zero to 10 miles from the treatment plant.
2. "Suburban" construction cost curves apply for pipeline installations
between distances of 10 and 20 miles from the plant.
3. "Rural" construction cost curves apply for pipeline installations at
distances greater than 20 miles from the plant.
Truck and Ra i1
The primary source of information used in developing truck and rail
haul total annual cost curves were unpublished cost relationships developed
in the James River Comprehensive Water Quality Management Study (197' ~
1973), updated to March 1975. These unpublished cost relationships were
developed by obtaining sludge haul bid costs from tank truck and rail
haul carriers as a function of wet tonnage hauled and haul distance, and
were updated by direct contact with the haulers to obtain cost escalation
factors.
Barg ing
Barging costs were developed using the barging economics model developed
by Clark e_t^ aj_ (Reference 7). The steps used in updating the parameters
in this model were as follows:
1. Barging capacity was assumed to cost $3^0/ton (Reference 8), and towing
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costs (at eight knots) were estimated as follows, using updates of
data from References 9 and 10:
Barge Capacity (Tons) Towing Cost ($/hr)
8,000 300
5,000 225
2,000 150
2. Total annual barging cost curves were constructed as a function of
annual wet tonnage hauled, barge size, and haul distance.
3. From the above curves, the least total annual cost was defined as a
function of annual tonnage and haul distance, and a second set of cost
curves defining least annual cost as a function of annual tonnage and
haul distance were constructed.
1*. The resultant cost curves were compared with cost projections for
sludge barging (Reference 9) from Philadelphia and DuPont (exemplary
of the "simple" case) and New York (representative of the
"complex" case).
5- Excellent comparison was found between the Philadelphia cost projections
and estimates for the Philadelphia and DuPont cases developed using
the updated economic model; however, it was found that unit sludge
barging costs ($/wet ton) for New York were about twice those estimated
using the updated economic model.
6. Based on the preceding comparisons, two sets of barging cost curves
were developed, one each for the:
a. "Simple" case, using the cost curves constructed with the updated
economic model.
b. "Complex" case, constructed by escalation of the cost curves
for the "simple" case by 1001.
ULTIMATE DISPOSAL METHODOLOGIES
Landfi11 ing
Landfill capital, 0/M and total annual costs were estimated as follows:
1. Landfill construction cost (excluding land) and 0/M costs were developed
using cost relationships presented by Wyatt and White (Reference 11).
2. Land costs were estimated using the unit land costs presented earlier
in this section and a land requirement rate of 3-75 x 10 acre/ton
of sludge (wet or dry)/year (Reference 12).
3. Land costs were estimated to provide land for five years of operation,
and no salvage value was assumed for the land.
Landspread ing
Landspreading capital, 0/M, and total annual costs were estimated as follows:
8
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1. An application rate of 10 tons dry solids/acre/year (Reference 13)-
2. Distribution costs at $20/day/ton dry solids (Reference 1*0 and land
preparation costs of $2,000/acre (Reference 12).
3. The purchase and salvage value of the land required were assumed to
be equal; the net annual cost of the land was estimated as equal to
the annual interest cost on the purchase price of the land.
COST RELATIONSHIPS
The initial objective in the assessment of the 288 sets of cost data
developed for Alternatives I to V was to develop a single-page graphical
presentation allowing the user to:
1. Estimate graphically the following types of costs, by alternative,
type of treatment, flow rate, and type and distance of residuals
transport:
a. Capital costs.
b. 0/M costs, in units of cents per 1,000 gallons, and dollars per year.
c. Total annual costs, as the sum of amortization and 0/M costs,
in units of cents per 1,000 gallons and dollars per year.
In the processes of evaluating the sets of cost data and exploring ways
to develop the presentation, it was observed that:
1. Because of the lack of ready information on capital costs for acquiring
truck, rail, and barging systems, estimates could be obtained only
for contract hauling (i.e., for total annual costs), and no breakdown
could be developed for amortization and/or 0/M costs for these
transport methodologies.
2. While barging costs were found to be variable with respect to distance
at a given flow rate and treatment level, such was not the case for
the land disposal alternatives (Alternatives I, IV, and V). The
total annual costs for Alternatives I and V were found to be distance
independent, and those for Alternative IV were found to vary +_ 20 percent
at each haul distance with respect to the average value for all
distances at a given flow rate and treatment level.
3. The latter circumstance, i.e.", the absence of a trend of increasing
total annual cost with increasing land haul distance, at a given
fTow rate and treatment level, was fortuitous in that it reflects
the values of unit land costs selected for the analysis (see subsection
entitled GENERAL COST ESTIMATING CONDITIONS).
4. That is, for the schedule of unit land costs selected for the evaluation,
the sum of transport and land disposal costs on a total annual basis
was nearly equal at each haul distance, for all haul distances, in
each land disposal based alternative at the same flow rate and treatment
level.
Because of the preceding circumstances, it was necessary/possible to
adjust the framework of the graphical presentation as follows:
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1. Capital costs are presented graphically only for the sludge processing
and land disposal related elements of each alternative; no capital
costs are included in any alternative for the transport element, such
that the capital costs for each alternative are distance independent.
2. Total annual costs for the land based alternatives are presented
graphically for the sludge processing land disposal related, and
transport elements on a distance independent basis.
10
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SECTION IV
SLUDGE DISPOSAL COST CURVES
A graphical presentation of the sludge disposal cost curves is presented
in Figure 2. The elements of the cost curves are as follows:
1. A flow rate scale ranging from 1 to 1,000 MGD.
2. Capital cost scales for the primary and secondary treatment subalter-
natives within each alternative, wherein capital costs are included
for the sludge processing and land disposal elements within each
subalternative.
3. Unit cost scales (in units of cents per 1,000 gallons) for each sub-
alternative; "unit cost" is defined as the normalized total annual
cost, inclusive of amortization and 0/M costs, for the sludge processing,
transport, and disposal elements of each alternative.
k. "Slant lines" for determining unit costs for barging disposal at one
way ocean haul distances of 15, 50, 80, 110, and 150 miles.
5- A "slant" line for determining unit costs for the land disposal
alternatives as a function of haul distances between 20 and 150 miles.
6. A nomograph for determining total annual cost (dollars per year) as a
function of flow rate and the unit cost for a given subalternative at
that flow rate.
The procedure for using the diagram is as follows:
1. Select flow rate, treatment level, alternative, and haul distance
(haul distance If an ocean disposal alternative is selected).
2. Enter flow rate on the "0_, MGD" scale in the upper left hand corner
of th° graph.
3- Read capital cost by moving rightward horizontally across the capital
cost scales; guide scales are provided at either side of the capital
cost scales to assist *1ineup of the straight edge.
^4. Read unit cost by reading horizontally from the "0_, MGD" scale to
the deflector line; proceed vertically downward to the appropriate
slant line; then read unit cost by moving rightward horizontally
across the unit cost scales; guide scales are provided to assist lineup
of the edge at each step.
5. Using the selected flow rate, the unit cost as determined above, and a
straight edge, enter the "Nomograph for Determining Total Annual Cost"
and read total annual cost directly.
11
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PAGE NOT
AVAILABLE
DIGITALLY
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SECTION V
REFERENCES
1. McMichael, W. F. Cost of Flotation Thickening of Waste Activated
Sludge. U. S. Environmental Protection Agency, National Environmental
Protection Agency, Cincinnati, August 1972.
2. Van Note, R.H. e± a_L A Guide to the Selection of Cost-
Effective Wastewater Treatment Systems. Prepared by Bechtel Corporation
for U. S. Environmental Protection Agency, EPA-430/9-75-002, July 1975,
Page 11-44 and Appendix B
3. Van Note, R. H. et_ aj_. Op_. cit. Page 11-48 and Appendix B.
4. Van Note, R. H. e_t^ aj_. Q£. c_i_t_. Page 11-53 and Appendix B.
S. Van Note, R.H. et §_]_. Op., cit. Page 11-38 and Appendix B.
6. Thompson, T. L. et_ a_K Economics of Regional Waste Transport and
Disposal Systems. Presented at the Third Joint AICHE-IMIQ Meeting,
Denver, Colorado, September, 1970.
7- Clark, B.D. e_t^ a_l_. The Barged Ocean Disposal of Wastes. A Review
of Current Practice and Methods of Evaluation. U. S. Environmental
Protection Agency, Pacific Northwest Water Laboratory. Pages 81-90.
July, 1971.
8. Wyatt, J.M. and P. E. White, Jr. A Methodology Guideline for the
Ultimate Disposal of Solid Wastes. Prepared by Engineering-Science,
Inc. for U. S. Environmental Protection Agency. Page VII-7-
February, 1975.
9- Mosser, William. Personal communication. April, 1975-
10. Economic Aspects of Ocean Activities. Vol. III. Economic Aspects
of Solid Waste Disposal at Sea. Massachusetts Institute of Technology.
Appendix. Pages IV-1 to 6. March, 1970.
11. Wyatt, J. M. and P. E. White, Jr. OJD. cit. Figure Vlll-l.
12. Municipal Sewage Treatment: A Comparison of Alternatives. Prepared
by Battelle Pacific Northwest Laboratories Council on Environmental
Quality and Environmental Protection Agency, 1974.
13- Rutgers Symposium Reviews Land Disposal of Municipal Effluents and
Sludge. Compost Science. Vol. 14. Page 26. March, 1973-
14. Wyatt, J. M. and P. E. White, Jr. 0£. cit. Page VI11-40.
13
*U.S. Government Printing Office: 1975-681-880/115
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