&EPA
United States
Environmental Protection
Agency
Office of Water and
Waste Management
Washington, DC 20460
January 1980
Solid Waste
Codisposal of Municipal
Solid Waste and
Sewage Sludge
An Analysis of Constraints
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Prepublication issues for EPA libraries
and State Solid Waste Management Agencies
CODISPOSAL OF MUNICIPAL SOLID WASTE AND SEWAGE SLUDGE
An Analysis of Constraints
This report (SW-184) describes work performed
for the Office of Solid Waste under contract no. 68-01-4427
and is reproduced as received from the contractor.
The findings should be attributed to the contractor
and not to the Office of Solid Waste.
Copies will be available from the
National Technical Information Service
U.S. Department of Commerce
Springfield, VA 22161
U.S. ENVIRONMENTAL PROTECTION AGENCY
1980
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This report was prepared by Gordian Associates Inc., Washington,
B.C., under contract no. 68-01-4427.
Publication does not signify that the contents necessarily re-
flect the views and policies of the U.S. Environmental Protection
Agency, nor does mention of commercial products constitute endorse-
ment by the U.S. Government.
An environmental protection publication (SW-184 c) in the solid
waste management series.
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ACKNOWLEDGEMENTS
This report was prepared by Dick Baldwin, Tom Barnett,
Dick Richards, and Jim Price under the direction of Harvey
Gershman of Gordian Associates Inc. Also, Klaus Feindler
of Quantum Associates served as a technical consultant on
this project. The authors wish to acknowledge the valuable
assistance provided by the EPA Project Officer, Dave Sussman
and the many members of the solid waste and wastewater treat-
ment industry who contributed time and information to this
effort.
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CONTENTS
Acknowledgement s
Preface
1. Introduction 1
1.1 Background 1
1.2 Highlights of the Report 2
1.2.1 Overview of Codisposal Alternatives (Chapter 2) 2
1.2.2 Institutional Factors Affecting Codisposal 4
(Chapter 3)
1.2.3 Implementation Examples of Codisposal 4
(Chapter 4)
2. Overview of Codisposal Alternatives 5
2 .1 Municipal Solid Waste 5
2.1.1 Municipal Solid Waste Disposal Alternatives 5
2.1.2 Cost Estimates for Municipal Solid Waste 18
Disposal >
2.2 Municipal Sewage Sludge 24
2.2.1 Sludge Disposal Alternatives 24
2.2.2 Summary of Sludge Disposal Costs 33
2.3 Codisposal Processes 36
2.3.1 Codisposal in a Sanitary Landfill 37
2.3.2 Codisposal in Conventional MSW Incinerators 41
2.3.3 Codisposal in a Sludge Composting Operation 43
2.3.4 Codisposal in a Multiple Hearth or
Fluidized Bed Sludge Incinerator 46
2.3.5 Codisposal in an MSW Waterwall Combustion
Furnace 49
2.3.6 Codisposal in an MSW Dedicated Boiler System 52
2.3.7 Codisposal in an MSW Modular Incinerator 52
2.3.8 Codisposal in an MSW Pyrolysis System 55
2.3.9 Summary and Conclusions 57
2.4 Economics of Codisposal 58
2.4.1 Landfilling 60
2.4.2 Conventional Coincineration 61
2.4.3 Composting Codisposal 61
2.4.4 Codisposal in an MHF/FBH 65
2.4.5 Waterwall Coincineration 67
2.4.6 Dedicated Boiler 67
2.4.7 Modular Combustion Unit 67
2.4.8 Copyrolysis 67
2.4.9 Summary and Conclusions 72
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3. Institutional Factors Affecting Codisposal
3.1 Organizational Issues 75
3.1.1 Planning Constraints ^7
3.1.2 Financing 80
3.2 Legal Isssues 83
3.3 Conclusions 87
3.3.1 Legal and Market Structure Issues 87
3.3.2 Planning Constraints 88
3.3.3 Financing Alternatives 89
4. Implementing Codisposal 95
4.1 A Few Real World Situations 95
4.1.1 Ansonia, Connecticut 95
4.1.2 Central Contra Costa County, California 97
4.1.3 Duluth, Minnesota 101
4.1.4 Glen Cove, New York 107
4.1.5 Harrisburg, Pennsylvania 109
4.1.6 Minneapolis - St. Paul, Minnesota Ill
4.2 Codisposal as an Alternative to Ocean Dumping 116
References 122
Appendix A. Municipal Solid Waste Economic Data. 129
Appendix B. Municipal Sewage Sludge Economic Data 142
Appendix C. Sludge Disposal Planning Activities of 167
Ocean Dumping Communities
Appendix D. Codisposal at Krefeld, West Germany 174
Appendix E. List of Abbreviations 203
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PREFACE
Data on codisposal was scarce or non-existent and
had to be gathered from an unusually disparate group
of public and private bodies. Work commenced on this
project in the summer of 1978 and, for a number of rea-
sons including delays caused by waiting for pertinent
Federal regulations to be issued and lengthy review pro-
cesses, the report was not completed until late 1979.
Unfortunately, it was not possible to update some of
the economic data that was gathered at the beginning of
the work effort. The reader should note that, as a re-
sult, the cost figures presented relate to mid 1978 le-
vels and therefore do not reflect the sometimes signi-
ficant prices increases of the past year. This time-
lag is true only for economic data. The information
concerning the status of technologies, existing or
planned projects, and Federal legislation has all been
updated and is current as of December 1979.
The reader should bear in mind that the major purpose
of this report is to provide an overview of the signifi-
cant issues confronting codisposal rather than to detail
specific economic or engineering data. In that sense,
this report should be a valuable reference document for
anyone seeking a better understanding of the codisposal
of refuse and sludge.
It should also be noted that EPA's Resource Recovery
Branch will soon be issuing updated versions of their
"Resource Recovery Plant Implementation: Guides for Muni-
cipal Officials" series. The new versions will include a
volume on codisposal.
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1. INTRODUCTION
1.1 Background
This report was prepared for EPA's Office of Solid Waste under
Contract No. 68-01-4427 (Task 14). Its' purpose was to assess the
nature and importance of institutional and economic factors asso-
ciated with the codisposal of municipal solid waste (MSW) and
municipal sewage sludge (MSS).
The study effort for the report was evolutionary in its nature,
commencing with an analysis of the relative cost of codisposal.
This seems a proper starting point, since, for most situations, if
codisposal is not economically attractive under some set of condi-
tions, then institutional problems are of no relevance. On the
other hand, if there is some cost advantage in codisposal, then
institutional issues will warrant close examination in order to
separate the significant obstacles frdm those which will be re-
moved almost reflexively when economic advantage can be shown.
The project examines eight distinct codisposal processes, as
well as the single-purpose solid waste and sludge handling pro-
cesses that would, if used together, comprise codisposal. The
processes are:
Single Purpose Single Purpose
Codisposal Solid Waste Sludge
Sanitary Landfill Sanitary Landfill Incineration
Conventional Conventional Landfill
Incineration Incineration Heat Drying
Sludge Composting Waterwall Combustion Composting
RDF in Sludge RDF
Incinerator Dedicated Boiler
Waterwall Combustion Modular Incinerator
Dedicated Boiler Pyrolysis
Modular Incinerator
Pyrolysis
For each process, the report presents a description and an
estimate of capital and operating cost for three scales of oper-
ation.
The analysis of relative costs was a problematic exercise,
because the available information on costs of wastewater residuals
and solid waste handling is replete with poor or conflicting data,
and there are a number of areas where relatively little is known
regarding process cost. In large part, the literature is intended
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to serve the needs of project planners who are able to specify
narrowly the dimensions of the systems they want to compare. As
a result, it is less useful as the basis for developing a set of
cost data that is consistent enough for comparison purposes.
A second thrust of study dealt with institutional issues, focusing
on three areas: organizational differences between wastewater and
solid waste management programs, planning and financing issues, and
legal issues. In this separate area, the literature is relatively
sparse, so that definite conclusions are not possible. Further, a
brief look at several codisposal projects around the country em-
phasized that institutional issues are as unique and site-specific
as engineering issues.
The data developed in the cost analysis served two purposes.
First, they enabled a comparison of the relative costs of various
codisposal options to be made. Second, they served as input to
an assessment of alternative approaches to EPA funding assistance
under recent provisions of the Clean Water Act.
In regard to limitations, it should be noted that this study
is intended to be highly general. Accordingly, the cost data, as
well as the institutional discussion, do not refer to events on
the level of a specific project, except for the analysis of funding
alternatives. The intent was to provide broad comparisons and con-
clusions regarding the economic and institutional viability of co-
disposal. Another limitation is that only municipal wastes are
considered in this report, excluding any discussion of the disposal
of industrial sludges or solid wastes.
Apart from the limitations in scope, the study is also restricted
as to the level to which any single issue could be developed. In
particular, this is evident in discussing issues of financing. Many
practical problems exist beyond the single question of EPA funding
policy. However, it was not possible within the study's time and
resource constraints to carry the discussion beyond what is shown
in Chapter 3, which compares several financing and cost allocation
procedures in a general way, using hypothetical data.
1.2 Highlights of the Report
The following is a brief listing of the major findings of each
chapter of the report.
1.2.1 Overview of Codisposal Alternatives (Chapter 2). This
section discusses both single purpose and multiple purpose sludge
and solid waste handling systems in terms of the criteria that indi-
cate their potential for further use in codisposal projects. Major
points are:
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• Extent of Use of Given Systems. Landfill is by far the most
widely used MSW disposal alternative, but it is perceived
as being restricted to some extent in the future by RCRA
requirements. Incineration is most widely used for sludge.
Of the codisposal processess, thermal methods seem to be the
most likely for the future. It is worth noting that the
literature indicates landfill codisposal to be a viable
process. However, it is not likely to apply in areas where
high technology codisposal is being considered.
• Relative Cost of Processes. Landfill is the least expensive
for both single and multiple purpose projects. If landfill
is prohibited, thermal methods are the next attractive al-
ternative. Thermal codisposal is a high technology option,
but it also shows significant scale economies. Our analysis
shows that codisposal is competitive with capital-intensive
single purpose processes and that it should always be con-
sidered.
• Status of Technology. Apart from landfill, the thermal methods
of MSW disposal appear to be the best understood. Similarly,
for MSS, thermal methods are well known, while the best-
developed codisposal options are those which relate to either
mass burning of MSW or sludge incineration. Pyrolysis, RDF
production, and composting represent the areas with greatest
need for technical or economic data development. In any case,
technologies are constantly evolving and, in general, more
data are needed.
• Future Prospects. EPA expects sludge incineration to grow
as a disposal alternative. For MSW, landfills will be able
to continue in many parts of the country. However, as energy
needs grow and as land-intensive options run out due to future
regulation, codisposal should be seen as an attractive alter-
native. This is particularly true in the populous north
eastern seaboard areas where landfill space is scarce and
communities are facing the 1981 ban on ocean dumping of
sludge, which is their current method.
• Other Issues. Relative rates of MSW and MSS in combination
were examined in the report. Based on dry weights, these
can range from equal parts sludge and solid waste, up to
greater than the 13:1 ratio that indicates equivalent populations.
Some processes are more flexible than others, with pyrolysis
and waterwall incineration showing the largest range of com-
binations. In general, however, the optimum rates of combin-
ation for most processes indicate that codisposal may not
represent a solution to disposal of both waste streams.
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• Policy Trends. Pending EPA decisions regarding codisposal
financing^ landfill regulations under RCA, and individual
state positions on exempting resource recovery from "offset"
regulations under the 1977 Clean Air Act Amendments will
significantly influence the future of codisposal.
1.2.2 Institutional Factors Affecting Codisposal (Chapter 3).
Three areas were found to constitute the most significant institu-
tional constraints:
• Organizational and Planning Issues. Because of the inherent
and programmatic differences in solid waste and wastewater
management, there are many points of significant difference.
The major items deal with problems in planning, many of which
can be resolved with an overview approach rather than con-
tinuing the current emphasis on specific project analysis.
• Financing Issues. The central issue is EPA's policy toward
funding. Several alternatives were examined, including one
which would not be based solely on formula allocations. In
general, it is not felt that EPA's funding policy is a major
obstacle, although it could be defined so as to be a more
positive incentive.
• Legal Issues. Waste control and interference with private
operations are the two major legal problems. These will be
dealt with over a period of time as court decisions and new
legislation begin to develop a body of law.
1.2.3 Implementation Examples of Codisposal (Chapter 4). The
report examines several current examples of codisposal, both success-
ful and otherwise. The data presented are merely objective summaries
of the projects, as opposed to analytical case studies. Also included
are contemporary reports on the plans of major East Coast ocean dumping
communities.
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2. OVERVIEW OF CODISPOSAL ALTERNATIVES
In discussing the constraints that might inhibit the broader
implementation of codisposal, it is important to frame the dis-
cussion in terms of the general viability of the various codisposal
alternatives. In planning, these alternatives would initially be
tested against standards of technical and economic feasibility.
If these tests indicate infeasibility, then no further action would
be warranted; the planning process would not be hindered by possible
institutional problems. This chapter examines codisposal relative
to the most widely used single-purpose sludge and solid waste dis-
posal practices. Its intent is to determine the approximate points
at which codisposal should be considered along with single-purpose
alternatives.
This chapter describes single-purpose sludge and solid waste
handling options and provides estimates of the cost per ton of
waste material disposed by each method. Codisposal processes are
also examined, along with estimates of the cost per ton for dis-
posal. In addition to cost estimates, the parallel issues of
financing, regulation, restrictions, and status of the technology
are discussed. These data are all drawn together to indicate the
boundaries of cost and feasibility where codisposal might be a
viable option.
The discussions of processes and disposal costs for both sludge
and solid waste are based on schematic, generalized processes. Cost
estimates for comparison among system options were developed by
drawing upon the broad estimates that can be found in the currently
available literature. The resulting cost data are approximate, but
they have been adjusted to the extent possible to eliminate differ-
ences in assumed unit costs, amortization terms and price levels.
The method of cost derivation is discussed in detail in this chapter
and in Appendices A and B.
2.1 Municipal Solid Waste
2.1.1 Municipal Solid Waste Disposal Alternatives. Seven major
alternatives for the disposal of municipal solid waste (MSW) are
discussed in this study, emphasizing those processes that have the
potential for compatibility with sludge disposal. The seven alter-
natives which are discussed below are: sanitary landfilling, con-
ventional (refractory-wall) incineration, waterwall combustion, RDF
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processing, dedicated boilers, modular incinerators with energy re-
covery, and pyrolysis. In addition to describing each process,
reference has been made to existing or planned examples, relative
cost data, the status of technology, external constraints, and fu-
ture prospects. Relative costs are summarized in Table 2.
Sanitary Landfills. This method of disposal handles
over 90 percent of the nation's solid waste stream. Its predom-
inance can be accounted for by the fact that in most cases land-
filling is the easiest, most reliable, and cheapest alternative.
A variety of landfilling methods may be followed, de-
pending primarily on the type and volume of the solid wastes, site
hydrology and the availability of cover material. In general, the
process consists of spreading the solid waste in thin, compacted
layers over a prescribed area of land, and then covering it each
day with the required amount of cover material. Usually the depth
and frequency of cover material are established by state or local
regulation.
Capital and operating costs are closely tied to site
factors and operating procedures. As a result, landfill disposal
systems display wide variations in cost. One of the primary vari-
ables is the cost of land, which ranges from nominal lease charges
in some rural areas to the high values found in many urban or subur-
ban communities.
Many of the landfill studies examined as sources for this
report showed lower average ton disposal costs than those developed
here. This was apparently due to a preponderance of low cost rural
landfills in areas that would be unlikely to have coincident sludge
disposal problems. Thus, the emphasis in this study was placed on
the higher landfill prices being paid in urban areas.
Landfills are required for the ultimate disposal of re-
sidues no matter what solid waste management system is employed.
Thus, they span the full spectrum of capacity in tons per day.
While there is no optimum size, it is generally recognized that
there are economies of scale to be gained from consolidating into
larger operations, up to the point of collection cost constraints.
The cost estimates in this report are based on landfilling
with unprocessed waste. Any additional costs or savings from shred-
ding and baling were not considered. It is not clear from the avail-
able data whether these processes add to or subtract from the net cost
of conventional landfilling, since their relative costs must be de-
termined for specific projects. However, two points of significance
for compatibility with sludge disposal should be noted: shredding
tends to increase the absorptive capacity of MSW, while baling
reduces it.
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Financing of landfills can take many forms, depending on
the scale of the project. The relatively low level of capital re-
quired, the typically public ownership, and the low risk nature of
the process make funding through general obligation bonds the most
popular approach. Many smalller landfills are financed entirely on
a "pay as you go basis," out of current revenue from general taxa-
tion. In our estimates, a capitial amortization period of ten years
was used since it is difficult to procure an area of land with suffi-
cient capacity for longer than that given the resistant climate of
prevailing public opinion.
At the moment, landfilling appears likely to be the
disposal method most directly affected by the requirements of the
1976 Resource Conservation and Recovery Act (RCRA). Section 4004
of the Act stipulates that specific criteria for acceptable land-
fills will be promulgated by EPA. These criteria have recently
been published (Sept. 1979) and it appears that their effect will
be to raise the cost of landfilling by imposing stricter standards,
especially for methane and leachate control. Landfilling will
probably continue to be the predominant method of waste disposal,
primarily because it will contine to be the cheapest alternative
for much of the nation's waste. Also, all of the more sophisticated
disposal alternatives leave some degree of residue that must ulti-
mately be disposed of in a sanitary landfill.
Incineration. This term covers a variety of specific
processes involving waste volume reduction through high temperature
oxidation and, in many systems, recovery of the energy released.
Incineration systems which recover materials and/or energy are dis-
cussed in subsequent sections. The present discussion is concerned
with those systems which incinerate waste for the purpose of volume
reduction. The incineration process is generally very effective;
reduction in excess of 90 percent by volume can often be achieved.
This has the effect of extending the landfill life by approximately
tenfold.
In a typical system (see Appendix A, '.Table A-2 for a
schematic diagram) waste is deposited in an unloading and storage
area. A furnace feed system passes the waste to a combustion
chamber where air is supplied in the quantitites required for thor-
ough combustion. Exhaust stacks must be equipped with a pollution
control device to clean up emissions and a means must be provided
for removing the residue.
Modular incinerators also perform as volume reduction
systems, but on a somewhat different principle. These units are
prefabricated and shipped to the site and consequently are suitable
for smaller volume of waste (5 to 30 TPD per unit), although
several may be co-located to achieve capacities of up to 150 TPD.
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The generalized system consists of a batch fed primary chamber
where raw MSW is combusted, usually under starved air conditions.
The resulting volatile gases are burned in a secondary combustion
chamber before being fed to an air pollution control device. If
combustion temperatures are kept high enough, emission control is
relatively easy and inexpensive.
Both of the systems described above, operate as mass
burning incinerators, which do not process the waste prior to
materials recovery. Extremely large or dangerous objects may be
sorted prior to incineration, but the remainder of the non-combus-
tibles are landfilled as part of the residue. Both systems also
require relatively small amounts of fossil fuel for start-up and
maintaining proper operating temperatures.
The system costs shown in Table 2 do not include any
allowance for residue materials recovery, although it is techni-
cally possible.* "Back end" materials recovery is considered to
be so economically questionable at this time that there is not
enough activity to warrant its inclusion. It can be ssen from
Table 2 that both systems have comparable costs, but at signifi-
cant scale differences, with an average value of $12.50 for re-
fractory wall (500 TPD) compared to $12.00 for modular incinerators
(50 TPD). When compared at their only commonly-calculated capacity
of 100 TPD, the modular system is more attractive: $9 per ton vs.
$15 per ton. The much higher excess air requirements of refrac-
tory wall incinerators and the resultant air pollution control costs
are a significant aspect of the higher costs.
A recent study of emissions from refractory type incin-
erators concluded that not only are suspended particulates a prob-
lem, but also "that incinerators are the major source of airborne
Cd, Zn, Sb and possibly, Sn and Ag in many areas."** The increasing
concern over the detrimental health effects of these substances may
lead to more stringent controls and therefore higher costs for this
disposal approach.
Modular units, operating on a starved air principle, gen-
erally have less difficulty in meeting emission standards with less
costly scrubber-type devices. Further, the systems can be adapted
to numerous smaller communities with landfill problems, for whom
high technology alternatives would be inefficient.
*A summary of MSW economics is shown in Table 2 on page 19.
**Greenberg, Zollen, and Oordon. "Composition and size distribution
of narticles released in refuse incineration."
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In volume reduction systems such as these, no revenues
are generated and operation represents a cost to be offset or
covered entirely by tipping fees. Financing can often be accom-
plished through the public pwnership options of short term bank
borrowing, general obligation bonds, or leasing from or contracting
with private firms. The method selected depends on the amount of
capital required and the community's financial condition. Contrac-
ting with a private firm may well prove to be more efficient, re-
gardless of the community's financial situation.
Mass Burning Waterwall Combustion Systems. A waterwall
furnace is a combustion chamber whose walls are lined with tubes
containing circulating water. The water recovers heat radiated
from the burning waste to be used in steam generation. Combustion
takes place on grates of varying design, which keep the waste moving
while allowing air to circulate for thorough combustion. Combustion
gases are passed through air pollution control devices (usually elec-
trostatic precipitators) prior to venting (A generalized system is
shown in Appendix A, Table A-3). This type of furnace has become
the clear favorite in the large scale burning of solid waste because
of its relative ease of maintenance and high efficiency in heat trans-
fer.
A listing of major existing or olanned resource recovery
facilities is shown in Table 1. At present, the smallest operating
waterwall combustion facility in the U.S. is the Navy's 360 TPD
capacity system in Norfolk, Virginia. A smaller facility is planned
in Hampton, Virginia (200 TPD). Most existing or planned facilities
are larger in order to capture the economies of scale evident from
Table 2.
This system discussion also assumes that no front end
processing occurs (although several have shredders for oversize
objects), and no back end recovery occurs; therefore, no materials
recovery revenues are realized. As noted earlier, revenues from
steam generation are quite variable. An important determinant of
a steam price is whether the steam can be supplied on a "firm"
basis, as with most fossil fuel produced steam, or if at a lower
price, an interruptible agreement is possible. In most cases, MSW
generated steam is sold to users who already possess steam producing
capabilities or who must build standby systems to ensure production,
and therefore need an incentive to purchase power from a new source.
The incentive is usually in the form of a reduced price compared to
the alternative fossil fuel price. For users with their own
steam generation capabilities such as utilities, MSW steam is us-
ually sold as supplementary power at reduced peak load prices
compared to the higher base load rates. Current agreements by
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10
TABLE 1
CURRENT STATUS OF MAJOR RESOURCE RECOVERY PROJECTS*
DISPOSAL x
ALTERNATIVES '
MASS
JNCINERATION--
WATERWALL
COMBUSTION
REFUSED DERIVED
- Fluff
- Dust
~ Wet
- Densified
DEDICATED
BOILERS
MODULAR
INCINERATORS
PYROLYSIS
- Landgard
- Torrax
- Furox
- Garret
ORIGINAL OR ESTIMATED
CAPITAL COST
LOCATION (S X 1000) CAPACITY
Harrisburg, PA
Saugus, MA»
Nashville, TN
Norfolk, VA
Braintree, MA
Chicago, II,
FUEL
Lane County, OR
Chicago, IL
Baltimore, MD
Ames, IA
Milwaukee, WI
Monroe County, NY
New Orleans, LA
Bridgeport, CT
E. Bridgewater, MA
Newark, NJ
Franklin, OH
Hemps tead, NY
Dade County, FL
Akron, OH
E. Hamilton, ONT
Niagara Falls, NY
Blytheville, AR
Grove ton, NH
Salem, VA
Siloam Springs, AR
Auburn, ME
N. Little Rock, AR
Baltimore, MD
Luxembourg and France
S. Charleston, W VA
San Diego, CA
12,800
61,000
32,600
5,537
4,850
39,100
2,100
19,000
8,400
7,600
18,000
32,400
7,750
53,000
10,000-12,000
70,000
5,440
73,000
60,000
46,000
9,000
65,000
976
305
501
29,200
-
17,290
15,500
720 TPD
1200 TPD
720 TPD
360 TPD
240 TPD
1600 TPD
500 TPD
1000 TPD
600-1500 TPD
200 TPD
1600 TPD
2000 TPD
700 TPD
1800 TPD
1200 TPD
3000 TPD
150 TPD
2000 TPD
3000 TPD
1000 TPD
600 TPD
2200 TPD
50 ITU
30 TPD
100 TPD
19 TPD
150 TPD
100 TPD
600 TPD
-
200 TPD
200 TPD
STATUS
Operational since ;1972
Operational since 1975
Operational since 1974
Operational since 1967
Operational since 1971^
Operational since 1971
(in shakedown)
Operational by Fall 1978
(in shakedown)
Full Production by Fall 1978
Testing
Operational since 1975
(in shakedown)
Partially Operational
Startup by 1979
In shakedown
Operational in 1979
Testing
Operational in 1980
Operational since 1971
Testing
Startup scheduled
Operational in 1980
Operating at 300 TPD
Operational in 1980
Operational since 1975
Operational since 1975
In shakedown
Operating since 1975
In final negotiations
Re-started Summer 1979
Operational since 1974
Demonstration Plant, now clos
* Source: Gordian Associates Inc.
t Landfill and/or Incineration without resource recovery are found in most major cities ana
many other areas. Capital and capacities vary widely as discussed 1n text.
f Recently shut down; see text.
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11
MSW steam purchasers are in the range of $2.75 to $3.50 per 1000
Ib. of steam, which is about $0.50 to $1.00 below in-house gener-
ation costs.* For this study an average price of $3.00 per 1000
Ib. steam was used. Steam revenues per input ton of MSW are based
on the above price multiplied by the amount of steam produced per
input ton. Current waterwall boilers can produce up to 6000 Ib.
steam per ton of MSW, therefore earning $18.00/ton from the sale
of steam.
Due to the large capital requirements and revenue pro-
ducing nature of this system, the most common form of financing
is through either municipal or industrial revenue bonds. The
method selected depends on who owns and operates the facility (if
public, then municipal revenue bonds), the amount of capital re-
quired, and alternative sources of that capital. For large, insti-
tutionally complex projects, a combination of approaches will often
be employed.
Mass burning waterwall technology in general is well
developed, with the European waterwall experience paving the way
for U.S. expansion of that process. European system manufacturers
such as VKW, Von Roll, and Widmer-Ernst have a total of over 100
facilities in operation in Europe. In fact, most waterwall processes
in this country involve American franchises for a European manufac-
turer. For mass burning systems, slagging and corrosion of water
tubes, along with larger than expected levels of residue have created
some difficulty, but the biggest problem in early U.S. plants has
been meeting stringent air quality standards. Modern electrostatic
precipitators have proven to be capable of meeting these requirements.
The short term future for waterwall incineration looks
promising. The technology is well developed and the economics appear
to be competitive with other disposal options. Consequently, many
communities (see Table 1) are commiting themselves to the major
investment which this process requires.
Refuse Derived Fuel (RDF) Processing. The basic RDF system
processes municipal solid waste to produce a transportable supplemental
solid fuel for use in fossil fuel fired energy systems. This fuel pro-
duct currently is made in several forms, but the processing approach
is very similar for most systems (Black Clawson's hydra-pulping being
a notable exception). A represntative system employing a composite
of the state-of-the-art processes is shown in Appendix A, Table A-6.
*Gordian Associates, "Overcoming Institutional Barriers to Solid
Waste Utilization As an Energy Source".
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12
Basic full materials recovery systems such as this employ a complex
processing train to separate ferrous metals, aluminum, and glass.*
Approximately 75 percent by weight of the incoming solid waste exits
the system as RDF, consisting mainly of paper and light organics,
and containing 5500-6500 Btus/lb. The initial trommeling stage and
secondary shredding step shown in Appendix A are the most recent
attempts to reduce maintenance costs and increase materials recovery
while producing a cleaner burning fuel.
The form of the end product RDF is the major distinguishing
feature among systems. The most common type is fluff-RDF, which re-
sults from the processing described up to this point. The best examples
of this system are found in Ames, Iowa, St. Louis, and AmericologyTs
plant in Milwaukee. "Hydra-pulping" also produces fluff-RDF. The
process has been demonstrated at Franklin, Ohio; a large scale plant
is operational at Hempstead, New York and planned for Dade County,
Florida.
Another promising form for the final product to assume
is termed dust-RDF. In this process, the shredded waster undergoes
a further step which coats the light portion with an embrittling
agent. This allows the waste to be fragmented into tiny particles
which have a higher Btu per pound value and burn more evenly than
standard fluff-RDF. The main proponent of this system is CEA/OXY, !
with a plant in shakedown in Bridgeport, Connecticut and planned
for Newark, New Jersey.
The third approach to RDF processes the shredder waste
through an additional stage which densities the product into pellets
of varying size and shape. This "densified RDF" is designed to be
of the same general size and consistency as Crushed coal, which
simplifies handling and feeding adaptions for conventional coalfired
boilers. The process has been demonstrated at the NCRR facility in
Washington, D.C. and is also being tested by Detroit Edison. The
design of the end product RDF is dependent on the specific type of
boiler that it will fuel. The minimization of adaptation costs is
generally the objective of this process.
There is significant variance in the capital required
for the alternative processes. Fluff-RDF is the least expensive
system to construct, averaging $17,000/per daily design ton of capa-
city, with wet, densified, and dust systems ranging from $2000 to $5000
more per daily design ton.
*This study assumes that revenues from materials recovery will be
about $3.40 per input of MSW. For details on this assumption.
see Section 2.1.2
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13
Revenues from the sale of RDF are extremely variable and
dependent on the following factors.
• The energy recovery efficiency of the process - i.e., the BTU
content of the RDF expressed as a percentage of the Btus avail-
able in the input MSW. The efficiencies used here are based on
EPA data.*
• The price of the alternative fossil fuel which is currently be-
ing used or would be used in place of the RDF. In most instan-
ces, this fuel is coal since RDF is most compatible with coal
fired systems. The price assumed here is a national average
figure of $1.00/Mbtus.**
• The degree of difficulty which energy users will have in con-
verting their systems to burn RDF. This can be expressed in
terms of a discount in the price which RDF would commmand
if compared directly with fossil fuel on a Btu basis. This
"handling charge" varies with the physical form of the RDF.
Since pelletized RDF is designed to be compatible with crushed
coal feed systems, the discount is smaller. Dust-RDF also can
easily be adapted to pulverized coal burning boilers at com-
paratively little cost. These variations are reflected in the
energy revenues per ton of MSW shown in Table A-4 through A-6
in Appendix A.
As with waterwall systems, RDF systems are most often fin-
anced through revenue bonds. However, almost as many current or pro-
posed systems utilize state or local general obligation (GO) bonds for
their funding. The amount of funding available through GO bonds is
limited to statutory debt ceilings which may be a severe constraint for
communities already at or near that mark. GO bonds also require voter
approval. But, unlike revenue bonds, which are subject to the scru-
tiny of the underwriters, GO bonds do not require feasibility studies.
This often means that a project must be more clearly defined and well
researched in order for revenue bond sales to be successful.
The technology of producing RDF must still be considered
developmental at this point. Although a number of pilot and de-
monstration plants have been set up and many full scale facilities
are in the planning and construction stages, there are very few
commercially operational RDF systems in existence. Consequently,
the widespread endorsement of this approach is being withheld for
fear that newer technology will render recently acquired systems
obsolete. There have also been technical problems involving the
materials recovery process for aluminum and glass, the extreme wear
and downtime of shredders, and the handling of RDF. Two areas are
especially troublesome: RDF is proving difficult to store due to
its varying moisture content, microbial decomposition and potential
fire and explosion hazard; experience to date has shown that process
lines involving shredders must find ways to contend with the threat
of explosions. This danger has increased the popularity of trommel ing
as an alternative or supplement to shredding. To ensure continuous
*U.S. EPA, "Technologies; Resource Recovery Plant Implementation", p. 23
**U.S. FEA, Monthy Energy Review, August 1978.
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14
operation in the face of frequent breakdowns, costly redundancy
must be built into the system. Special consideration must also
be given to the compatibility of RDF with boilers and their present
fossil fuels. Current results indicate some minor problems with
slagging and corrosion and more difficult problems of handling
increased ash levels.
At present, federal and state regulations exert few
constraints on RDF facilities. As with all high technology systems,
emission standards necessitate elaborate and expensive pollution
control equipment on the stack of the fuel user. The study of in-
cinerator emissions cited earlier* also noted that RDF burning may
not generate the same level of noxious pollutants as mass burning
because the removal of the metal and glass laden fraction of the
waste stream may assist in reducing certain emissions.
The future for RDF systems will be shaped mainly by the
success or failure of the technology to develop a reliable, easily
used fuel which is adaptable to many systems. The critical element
for success will be the development of a large scale market for the
product. The widespread public endorsement of this approach as en-
vironmentally sound has been a boon to its development. EPA predicts
the operation of 40 to 70 resource recovery plants by 1985, many of
which will be RDF producers in some form.** So, in spite of tech-
nological and market uncertainties, the RDF solid waste disposal
alternative seems assured of at least a promising short-term future.
Long term predictions depend, again, on records yet to be established.
If fossil fuel prices escalate as expected, the process of producing
energy from waste will inevitably become more attractive. Note that,
currently, RDF and sludge combustion is one of several major focal
points of codisposal interest.
Dedicated Boilers. There are many different system ap-
proaches which can be grouped under the heading of dedicated boilers.
In the generalized system used in this study, incoming waste is
trommeled, shredded, passed through materials separation processes,
air classified and often re-trommelled or reshredded before entering
a furnace chamber designed to fire RDF exclusively. Of special note
is the Black Clawson hydra-pulping processing approach which differs
from this description in that the incoming waste is wetted and pro-
cessed in basically the same manner as above, except as a slurry.
Not only can the RDF be produced through a variety of processes, but
the boiler as well can fire the fuel in several different configur-
ations. For this discussion a generalized system is assumed,
*Greenberg, Zollen and Gordon, op. cit.
**U.S. EPA, Solid Waste Facts, May 1978.
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15
consisting of a full materials recovery, fluff RDF-process train
combined with a semi-suspension combusion unit using a waste.heat
boiler.
Table A-7 in Appendix A shows annual costs broken down
into RDF processing costs and boiler costs. The average capital
requirement is $35,000 per ton of daily design capacity, with
$14,000 going for the RDF train and the remaining $21,000 for the
boiler system.
Materials and energy revenues are based on the same
assumptions as for the earlier RDF and waterwall systems, respec-
tively. Steam is again assumed to be produced at 6000 Ib. per input
ton of MSW and sells for $3.00/1000 Ib., generating revenues per ton
of $18.00. Steam revenues may be slightly understated since newer
semi-suspension boilers are capable of generating up to 8000 Ib. of
steam per input ton of MSW, utilizing much lower rates of excess air
than comparable mass burning waterwall systems (30 - 50 'percent vs.
100 - 150 percent). This increased efficiency may yield higher re-
venues but, as the evidence to date is not clear, no differences are
assumed here.
Operations and maintenace costs are also somewhat specu-
lative since the documented data are limited. The figures used here
are higher than many estimates to ensure a conservative net cost
figure that is more in line with the limited historical data from
North America's only large-scale operational dedicated boiler facility
in Hamilton, Ontario.*
Dedicated boiler systems are subject to the same envir-
onmental constraints as waterwall and RDF systems. There are no
major impediments to developments, other than ensuring that air
quality standards are maintained, and building the system reliability
that major markets demand.
The universal adaptability of steam as an energy product
is a distinct advantage for systems like waterwall incinerators and
dedicated boilers. This eliminates costly conversions for the buyer,
but also means that the MSW processing facility and steam purchaser
must be co-located (within two miles of each other), since steam
cannot be economically conveyed over much distance.
Modular Incinerators with Energy Recovery. Modular in-
cinerator (MI) systems which recover energy can be considered as a
*Estimates of operating costs for the Akron and Niagara facilities
appear to be optimistic in view of the Hamilton costs.
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16
case by themselves. The process is operational in North Little
Rock, Siloam Springs and Blytheville, Arkansas; Groveton, New Hamp-
shire; Crossville, Tennessee; and Salem, Virginia; with numerous
other community systems in the planning stages. As discussed
earlier, this modular approach is most suitable for small waste
streams. The energy recovery system is fundamentally the same as
for the earlier-described volume reduction process, except that a
waste heat boiler is installed to capture the heat released in the
flue gases from the secondary combustion chamber (see Appendix A,
Table A-8). Energy is recovered in the form of steam for sale to
nearby users.
The average capital cost for this system is $24,000 per
daily design ton of capacity, based on an average capacity of 50
TPD. No materials recovery is assumed from this system and steam
revenues are calculated on a different basis than for the larger
waterwall and dedicated boiler systems. Modular combustion units
have been generally less efficient than the large scale systems,
averaging around 4000 Ib. steam per ton input of MSW. However,
newer units are more efficient, approaching the efficiencies of the
waterwall units. Also, due to their batch-fed nature and relatively
small scale, MI steam contracts are often made on an interruptible
basis. This fact, coupled with the user's sunk capital in existing
in-house steam systems, necessitates a substantial price discount
to provide an incentive for steam buyers. A review of current
sources* shows this discount to average approximately 25 percent
lower than comparable fossil fuel derived steam prices.
Existing systems report financing methods which encompass
the full range of possible options. The small size and relatively
low level of capital required place modular incinerator systems more
within reach of private industry funding. There are several instances
where the private steam user is involved in the financing process to
a significant extent. However, most systems are publicly owned and
operated, and consequently have used current revenues, GO or municipal
revenue bonds as the source of funding.
Pyrolysis. The pyrolysis of solid wastes refers to the
thermal decomposition of wastes in the absence or near absence of
oxygen. It differs from incineration in that it is endothermic
rather than exothermic. The processes currently under development
use the potential energy contained in the waste to provide the heat
absorbed during the pyrolysis itself and recover the remaining energy
in the form of steam or a gaseous or liquid fuel.
*Steam contracts for the facilities at Salem, VA, Auburn, ME and
published data from Siloam Springs, AR. This discount is compar-
able to the waterwall and dedicated boiler pricing arrangement.
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17
A representative system is difficult to define since there
are currently no commercially operational pyrolysis plants in the
U.S. However, most of the systems have in common a pre-processing
system, a pyrolysis chamber, a fuel product, air pollution control
equipment, and some form of materials recovery (see Appendix A,
Table A-9).
The different systems currently being developed work
under these same principles with slightly different end products.
There are four major processes under development: The Baltimore
City "Landgard" system, which produces steam through combustion of
low Btu pyrolysis gases; the Andco Torrax System (operational in
Luxembourg, France, and Germany) is similar to the Landgard process
except that heat from low Btu gases is recycled to pyrolyze the in-
coming waste; the Union Carbide Purox System (Charleston, West Virginia)
which utilizes small amounts of pure oxygen to combust some of the
waste, generate the heat necessary to pyrolize the rest of the wastes
and produce a medium Btu gas for use as fuel; and the Occidental Flash
Pyrolysis system (San Diego) which processes the waste to produce
dust-RDF, which is pyrolized using by-products of previous reactions.
The product is a gas which is cooled to a liquid, oil-like fuel.
The different approaches to pyrolysis have enough points
in common to be grouped together into a generalized system for the
purposes of this discussion. Since the technology is currently prac-
ticed °n such a limited scale, the cost and revenue averages presented
here for different sized facilities are especially tentative.
The average capital cost per daily design ton of capacity
of a "representative" system is $39,000, with the Torrax system
costing the least ($29,000) and the Purox approach topping the range
at $47,000. This difference can be attributed to the lack of MSW
processing required for the Torrax system and the need for an oxygen
generating source for the Purox.
Revenues from materials and energy recovery vary to some
extent with the specifics of each system. The individual values
were averaged to arrive at the figures shown in Table 2. All systems
(except Torrax) recover at least ferrous metals, so the $1.50 per
input ton value assumed earlier for materials recovery was used.
Also, pyrolysis systems produce a residue which has peculiar charac-
teristics with potential for revenue as a road bed material. The
level of revenues that can be expected from the sale of this material
is not well documented; a net value of $1 per ton of residue was
used here. This translates to approximately $0.20 per input ton of
MSW.
The revenues available from energy recovery are derived
from the sale of pyrolysis fuel products; either gas of varying Btu
content or a liquid oil-type substance. The dollar value per input
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18
ton of MSW was determined on the basis of the reported Btu contents
of those fuel products compared to the national average price per
million Btus of the comparable fossil fuel product. In using these
fuels, the purchaser incurs fuel handling adaptation costs analogous
to those discussed for steam sales. This cost is represented by an
average 10 percent discount from the comparable fossil fuel price
which results in the $9.00 per input ton MSW value from energy re-
venues shown in Table 2. Note that this discount may not be large
enough if the gas has to be cleaned to pipeline quality or if very
significant fuel burning adjustments are required.
The biggest unknown factor associated with pyrolysis is
the status of the technology itself. Each of the proposed systems
has encountered an array of fundamental problems which have forced
delays, restarts and significant shifts in approach. Communities
and vendors are understandably reluctant to commit a major invest-
ment to a technology that is clearly still so developmental. It
should be noted that several of these systems have been tested uti-
lizing sewage sludge in the pyrolytic reaction and that this tech-
nology appears to be compatible with codisposal.
2.1.2 Cost Estimates for Municipal Solid Waste Disposal. Table
2 shows the estimated costs for each process based on a compendium
of the most current data available. Historical data were used when-
ever possible and published estimates were used where actual data
are not yet available. Much of the information came from the cen-
tralized data files of EPA's Resource Recovery Branch and the National
Center for Resource Recovery. All capital cost estimates were brought
forward to March 1978 by using the Engineering News Record construction
cost index (March 1978 = 2693). Amortized capital costs were made
comparable by using a standard 7 percent interest rate and a 20 year
amortization period. The data were then grouped by disposal process
type, and average per-ton values were derived. A range of 800 to
1200 TPD capacity was used since 80 percent of the available data
were for facilities of that size.
Capital costs are fairly well documented; operating cost
estimates are based on less reliable data. The "Gross Costs" shown
include operating and maintenace costs based on averages of available
data. There are numerous documented examples of the costs of constructing
a facility, but shakedown-related problems and long construction time
lags have prevented the development of as large a body of representa-
tive operating cost information. Furthermore, none of the operations
data can be presumed to represent the cost of a system operating at
its optimum level. In fact, there seems to be an emerging record of
systems being over-designed. Anticipated solid waste streams in
some cases have not materialized, so that operating costs per ton are
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TABLE 2
SUMMARY OF MSW ECONOMICS
DISPOSAL
ALTERNATIVES
LANDFILL
INCINERATION
Refractory
Modular
RESOURCE
RECOVERY
Waterwall
Incineration
RDF
Representa-
tive System
DEDICATED
BOILERS
INCINERATION
Modular
PYROLYSIS
Representa-
tive System
CAPITAL COSTS
$/design
ton
22* of total
annual cost
7,000-25,000
12,000-24,000
20,000-51,500
7,000-32,000
24,000-48,000
20,000-30,000
20,000-50,000
- . . .
GROSS COSTS
Range Average
S/ton $/ton
1.5-20.00 6.00
8.00-15.00 12.50
8.00-18.00 12.00
13.00-38.00 25.00
12.00-22.00 17.00
18.00-40.00 31.00
2.00-22.00 15.50
15.00-40.00 24.00
- - - ....
REVENUE
Range Avg. $/ton
$/ton Materials Energy
N.A. N.A. N.A.
N.A. N.A. N.A.
N.A. N.A. N.A.
7.00-30.00 18.00 N.A.
.90-16.30 3.40 4.60
7.90-30.80 3.40 18.00
6.00-15.00 N.A. 9.00
5.00-22.00 1.70 9.00
- - - - - - -
NET COSTS
Average
S/ton
6.00
12.50
12.00
7.00
9.00
9.60
6.50
13.30
ESTIMATES FOR THREE CAPACITIES
Capital Average Revenue Net
$/in Cost Value Cost
Capacity Thousands $/ton $/ton $/ton
100 TPD 385 8.00 N.A. 8.00
400 TPD 1,185 6.00 N.A. 6.00
1000 TPD 2,400 5.00 N.A. 5.00
100 TPD 1,500 15.00 N.A. 15.00
400 TPD 3,200 12.00 N.A. 12.00
1000 TPD 6,500 10.00 N.A. 10.00
10 TPD 225 16.00 N.A. 16.00
50 TPD 750 12.00 N.A. 12.00
100 TPD 1,250 9.00 N.A. 9.00
250 TPD 12,200 31.00 18.00 13.00
400 TPD 17,000 29.00 18.00 11.00
1000 TPD 31,000 25.00 18.00 7.00
250 TPD 6,750 22.00 8.00 14.00
400 TPD 8,800 20.00 8.00 12.00
1000 TPD 17,000 17.00 8.00 9.00
250 TPD 13,000 40.00 21.40 18.60
400 TPD 16,750 34.00 21.40 12.60
1000 TPD 32,000 30.00 21.40 8.60
10 TPD 360 20.50 9.00 11.50
50 TPD 1,250 16.50 9.00 7.50
100 TPD 2,000 14.00 9.00 5.00
250 TPD 12,500 32.00 10.7021.30
400 TPD 16,000 28.00 10.70 17.30
1000 TPO 13,600 24.00 10.70 13.30
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20
probably higher than expected. A good example of this is found
in the Hamilton, Ontario, dedicated boiler project, which was
designed to process 600 TPD but is currently averaging only 150
TPD. This disparity has had the effect of raising per-ton costs
from the predicted $15.00 per ton to over $46.00 per ton. Most
of the additional cost ($22.00) is due to charging fixed costs,
such as capital amortization, against a lower daily throughput.
Capital costs in most cases include all contingency,
engineering, legal and administrative costs, as well as bond ac-
quisition, site preparation and construction costs. Most opera-
tions are also designed with some measure of redundancy (less than
total in most cases) built into the processing streams. For most
of the system categories presented in Table 2, the range of unit
costs is broad. This appears to be the result of two factors:
one is the small number of resource recovery facilities in actual
operation, the other is the site-specific nature of most solid
waste disposal costs and revenues. The data base for solid waste
disposal costs is simply not yet broad enough for reliable genera-
lized economic determination. It should be recognized that these
data are used only as a reference point for the comparisons essen-
tial to this study.
The data with the greatest degree of variation are for
revenues from the sale of recovered materials or energy. The range
of values was determined from the referenced sources, but the average
revenues were adjusted based on Gordian's experience with existing
markets. Average material revenues were derived using EPA data for
waste stream composition and recovery probabilities, applied with
our best judgement as to prices for the recovered products at the point
of origin. For all materials recovery systems, the average revenues
are determined as ehown in Table 3.
For this study, all materials recovery systems are assumed
to be full front end recovery, using state-of-the-art processes. The
percentages and prices shown in Table 3 could be realized by recovering
ferrous metals magnetically, aluminum through the use of eddy current
separators, and glass via froth flotation. While not all recovery
systems recover each of these materials in this manner, the trend is
toward incorporating these technologies as possible revenue generators
should market conditions become favorable. Energy revenues are keyed
to the latest available* national values for the price per million Btus
of competing fossil fuels adjusted according to typical conversion effi-
ciencies for solid waste disposal processes.
The result of the cost and revenue computations is shown in
Table 2 as the average net cost per ton. This number does not include
any revenues from tipping fees. This net cost in effect represents the
fee that would have to be charged if the process were to break even.
*February 1978 price data as shown in U.S. FEA, Monthly Energy Review.
August 1978.
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21
In reality, tipping fees are often determined more by local influ-
ences or by the costs of alternative disposal options. For this
reason, no tipping fee is specified here; but, as the net figure
is presented in terms of dollars per input ton, it is easy to
calculate the effect of varying charges directly.
TABLE 3
REVENUES FROM MATERIALS RECOVERY
Market Value
% of % Recovery $/ton F.O.B.* $/ton
Material Waste Stream Possible Recovery Facilities MSW
Ferrous Metal
Aluminum
Glass
TOTAL
7
0.7
9
90
60
70
25
200
15
1.60
0.85
0.95
3.40
Costs and revenues have been estimated for three differ-
ent size facilities. As a result of the paucity of data noted above,
the estimates for each process size include an error margin on the
*Higher values are often reported but they usually reflect the
price obtainable at the buyer's facility, neglecting costs of
transportation. Also, recovered materials are generally of poor
quality and command a lower than premium price. These figures
represent Gordian's assessment of realistic current market values.
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22
order of + 30 percent. The estimates were made by plotting documented
costs for~~varying size facilities and estimating a curve relating cost
per ton to the scale of operations. These curves were adjusted with
data drawn from independent studies of apparent economies of scale
in solid waste disposal. The resulting values are in general agree-
ment with data developed by NCRR.*
Since most current or planned facilities are large (in the
1000 TPD range), the estimated cost curve is more clearly defined in
that range; costs for smaller facilities are less reliable. Three
different facility sizes were selected to provide a range of repre-
sentative values that would be appropriate to most communities where
these disposal systems would be applicable. The capacities for most
processes are 250, 400 and 1000 TPD. The lower limit is based on
the generally accepted size below which capital intensive resource
recovery systems become impractical. The upper limit was set because
economies of scale for most systems are not significant beyond 1000
TPD. However, these sizes could not be applied to all processes.
These deviations were noted in the preceding process descriptions.
System economics are influenced by the method of finan-
cing selected. The typical public/private financing alternatives
are well documented and are presented in Table 4 along with a range
of representative interest rates. Capital costs in this study have
been included in annual costs by amortizing over 20 years at 7 percent.
This interest rate is felt to be indicative of public ownership of
the facility, which is the case for the majority of existing or
planned solid waste disposal activities. However, a significant
trend is evident in that some resource recovery systems are being
developed through full service procurement approaches which result
in private ownership and operation.
Federal funding can play an important role in financing
a solid waste disposal facility, currently done through two major
source agencies, EPA and DOE. Conventional waste disposal (i.e.,
non-resource recovery) does not qualify for most of the federal
funding available. At present, funding from EPA is concentrated
on resource recovery or source separation programs; although money
has been available in the past for the construction of demonstration
projects, current EPA policy is to limit funding to the project
planning stages.
Under the "President's Urban Policy Program" now being
implemented, up to 75 percent of the costs incurred prior to design
and construction may be eligible for EPA funding. This program pro-
vides $15 million for this purpose in FY '79, as "implementation"
*NCRR Bulletin, Spring 1975, p. 43, fig. 2.
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TABLE 4
FINANCING OPTIONS
Financing Method
"Pay As You Go"
Borrowing
Leasing
Public Ownership
Financing Maximum Interest
Instrument Amount Rate (%)
Current $100,000(7)
Revenues
Short-term $500,000 14-15%
Bank
Borrowing
General Limited by 6-8%
Obligation municipality
Bonds debt ceiling
Municipal Unlimited 6^-8*5%
Revenue
Bonds
Simple — (Lease
Lease Rates -
(Govt. leases 15-20%
privately-owned of cap.
facility) costs)
Private Ownership
Financing Maximum
Instrument Amount
Interest
Rate (%)
Current $100,000(7)
Revenues
Short-term $500,000
Bank
Borrowing
Stock Unlimited
sales
Corporate Unlimited
Bonds
Industrial Unlimited
Revenue
Bonds
Pollution Unlimited
Control
Bonds
Leveraged Unlimited
Leasing
14-15%
___
10.5-12%
7-9%
7-9%
6-8%
* Source: Gordian Associates Inc.
NJ
OJ
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grants to states and local governments. Also, under the provisions
of RCRA, technical assistance for solid waste problems is available
through the EPA regional "panels teams." DOE has awarded planning
money under a similar program for projects which recover energy
from municipal solid waste. At this writing , a loan guarantee
program is also under consideration by DOE.
2.2 Municipal Sewage Sludge
2.2.1 Sludge Disposal Alternatives. The removal of pollutants
from raw municipal wastewater produces a stream of residual solid
material (sludge) consisting generally of the solid organic and
inorganic impurities that were present in the influent plus any
further solids added as part of the treatment process. Due to the
dilute, active, and unstable nature of raw sludge, various conditioning,
dewatering, and stabilization processes must be undertaken to treat it
before final disposition. Once treated, the sludge can be disposed of
through landfilling, land application, ocean dumping or incineration.
A detailed discussion of these various final disposal options is
presented in this section, including a description of the major sludge
processing trains associated with each final disposal option.
Both land-based sludge disposal practices and sludge in-
cineration represent disposal options which can be suitably adapted
to a codisposal alternative, providng that economic and. institutional
constraints are not prohibitive. To examine the economic viability
of codisposal as a sludge disposal alternative, cost estimates have
been developed for each of the sludge disposal options. Specific
information on the derivation of those estimates is presented in
this section and in Appendix B.
At its origin in the treatment process, the sludge stream
is highly liquid, typically containing less than 4 percent solids.
Prior to disposal, this stream must be treated to increase the
solids content and, in some cases, to stabilize its active biolog-
ical and chemical constituents. A number of different sludge hand-
ling and treatment techniques, shown in Figure 1, are currently in
use. In designing a sewage treatment process, the decision of which
sludge handling train to use is influenced by a number of variables,
including the nature of the sludge, estimated process costs, and
regulatory requirements. Sludge processes are also limited by the
locally available options for ultimate sludge disposal. For example,
if only limited landfill area is available, then incineration may
be the next most attractive option. Once decisions such as this
have been made, the nature of the process used to prepare the sludge
for disposal can be seen more clearly.
-------
SLUDGE INPUT
THICKENING
CONDITIONING
& STABILIZATION
DEWATERING
INCINERATION
PRODUCT RECOVERY
|
ULTIMATE DISPOSAL
PRIMARY
NO THICKENING
NO CONDITIONING
OR STABILIZATION
NO DEWATERING
ACTIVATED
SLUDGE
MODIFICATIONS
NO INCINERATION
SLUDGE-
HEAT RECOVERY\
SLUDGE -
WITH HEAT
RECOVERY
NO PRODUCT
RECOVERY
REFUSE
AND SLUDGE
COMPOSTING
SLUDGE
COMPOSTING
REFUSE AND
SLUDGE -
NO HEAT
RECOVERY
FERTILIZER
REFUSE AND
SLUDGE -
WITH HEAT
RECOVERY
PYROLYSIS
HEAT
DRYING
ANIMAL
FEED
PRODUCTION
CONSTRUCTION
MATERIALS
LANDFILL
LAGOONS
SURFACE
SPREADING
UNDERGROUND
PRODUCT
MARKETING
TRANSPORTATION MECHANISMS (PIPE, RAIL, TRUCK, BARGE)
Figure 1. Alternative sludge processing systems. Source: Stanley Consultants, sludge processing and disposal, (2)
-------
26
The first step in the sludge processing train is
usually thickening to reduce the water content and thus the volume
of the sludge. Gravity thickening, increasing the solids content
of the sludge through normal settling, is the most prevalent
thickening process. It has been assumed as a standard procedure
in the ensuing discussion.
Thickened sludge normally contains approximately 4 to 6
percent solids, therefore usually requiring further dawatering be-
fore final disposal. Chemical or thermal conditioning is typically
employed prior to dewatering in order to break up the gelatinous
structure of the sludge and allow for improved dewaterability. For
the purposes of this study, the technologies employed in sludge con-
ditioning are limited to chemical (alum, ferric chloride, or polymer
addition) and thermal conditioning.
Sludge dewatering processes are employed to reduce the
sludge to a cake of approximately 15 to 40 percent solids, depending
upon the particular process. One of the primary dewatering technol-
ogies in use today is the vacuum filter, which utilizes a pressure
vacuum to draw liquid sludge through a filter medium, capturing the
solids. The resultant filter cake generally contains approximately
20 percent solids (although higher percentages are possible). Filter
presses, which utilize pressures to force the liquid through the
filter medium, are used fairly extensively throughout Europe, but
have only recently been employed in this country. Although the
technology of batch processing with filter presses has proved to
be less reliable to date (in the U.S.) than that of vacuum filters,
the higher solids content of the resulting filter cake (up to 40
percent vs. the 20 percent from vacuum filters) can reduce or elim-
inate the fuel requirements for incineration, thereby establishing
a significant incentive for its adoption.
Sludge processing steps beyond the dewatering stage are
specific to the ultimate disposal option that is chosen. Land
disposal sludge must be stabilized prior to final application,
either through digestion prior to the dewatering step, through
composting, lime/chemical conditioning, or heat-drying subsequent
to dewatering. Aerobic or anaerobic digestion used as a sludge
stabilitizing technique results in a sludge suitable for landfilling.
Composting and heat-drying, on the other hand, conserve the nutritive
value of the sludge and make it suitable for use as a general soil
conditioner/fertilizer. Incineration represents another disposal
option, with landfill of the residual ash. The processing trains
defined for this analysis are shown in Figure 2. Alt6gether, seven
processes have been defined. Three relate to incineration, each
assuming a different method of prior dewatering: chemical condi-
tioning followed by vacuum filtering or filter press dewatering,
and thermal conditioning followed by vacuum filtration. The intent
-------
27
of these differences is to illustrate the trade-off among dewatering
processes to achieve differing solids levels prior to incineration.
Also, each incineration process distinguishes between multiple hearth
and fluidized bed incineration. The remaining four process trains
relate to anerobic vs. aerobic digestion prior to landfilling, or
landspreading and flash drying vs. composting prior to distribution.
An assumption has been maintained throughout this discussion that
the sludge would be 60 percent primary and 40 percent waste-activated,
with a volatile solids content of not less than 70 percent. It is
further assumed that the solids ratio of the influent approximates
870 dry Ib. per one million gallons per day.
Landfilling/Land Disposal. As Table 5 illustrates, approx-
imately 50 percent of the nation's sludge is disposed of through land
application, either through the landfilling/landspreading of liquid
or dewatered sludge, or through composting/heat drying of the sludge
with distribution for crop use.
Landilling accounts for approximately 25 percent of the
total sludge produced in the U.S. It involves the truck delivery
of stabilized, dewatered sludge to a sanitary landfill where the
sludge is spread and compacted. At the end of each day's work the
sludge is covered with a layer of soil. As the landfill is completed,
a deeper layer of earth is compacted over the fill and planted to
control erosion. If it is of good quality, dried sludge can be mixed
with the final cover to condition the soil. The methods for the
sanitary ladnfilling of sludge are well developed, as it has served
as one of the most prevalent methods of disposal for many years.
The major cost elements associated with sludge landfilling
derive from the transportation of the sludge to the landfill site,
land purchase or lease, and the operation and maintenance of the
landfill. In general, landiflling is a relatively inexpensive method
of sludge disposal, where suitable land is available within reasonable
hauling distances. We have estimated that landfilled sludge currently
costs $75.00 to $160.00 per dry ton for disposal, including dewatering.
-------
28
Thickened
Sludge
Option 1
Option 3
'
; Thermal
| Waste Liquor
1 to Treatment
i
k
Vacuum
fc
0
k
Incineration
in MHF
Option 3a
Option 3b
Incineration
in FBF
Ash to
^
Anaerobic
Digestion
J
Chemical
Conditioning
^
Vacuum
Filter
Landfill or
r Land Spread
Option 4
Aerobic
Digestion
w
Chemical
Conditioning
*
Vacuum
Filter
'
Landfill or
Land Spread
Option 5
Option 6
.
Chemical
Conditioning
.
Filter
Press
k.
f
Flash
Dryer
Distribution
Option 7
.
Chemical
Conditioning
h.
9\
Vacuum
Filter
r
Composting
Distribution
Figure 2. Representative sludge processing trains.
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29
TABLE 5
ESTIMATED CURRENT DISPOSITION OF SLUDGE*
Disposal Method % Total Sludge
Landfilling 25
Land Application:
Croplands 20
Others 5
Incineration 35
Ocean Dumping 15
*Source: 1974 Needs Survey, 1968 Inventory, Construction Grants
Files.
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30
Land Application. Another low-cost, land-based disposal
alternative which is gaining increasing popularity is sludge composting.*
Composting is a method of biological oxidation of the organic matter
in sludge by thermophilic organisms. Under good conditions, Compost-
ing can dewater the sludge and destroy its odorous components, destroy
or reduce the disease-producing organisms in the sludge because of
the elevated temperature, and produce an aesthetically acceptable
and useful organic product.
In the composting process, dewatered sludge (typically
at 20 percent solids) is delivered to the site and is usually mixed
with a bulking agent. The bulking agent increased the porosity of
the sludge to ensure aerobic conditions during composting. If the
composting material is too dense or wet, it may become anaerobic,
thus producing odors. If it is too porous, the temperature of the
material will remain low, delay the completion of the composting,
and reduce the killing of disease organisms.
Various bulking materials can be used; suitable low cost
materials include wood chips, bark chips, rice hulls, and RDF-type
portion of processed solid waste. Unscreened finished compost has
also been used. Generally, one part sludge (20 percent solids)
is mixed with three parts bulking agent, although this mixture can
be varied depending on the moisture content of sludge, type of
bulking agent, and local conditions.
Following composting, the product is removed and cured in
storage piles for 30 days or longer. This curing provides for
further stabilization and pathogen destruction. Prior to or
following curing, the compost may be screened to remove a portion
of the bulking agent for reuse or for applications requiring a finer
product. The compost can also be used without screening. Removal
of the bulking agent reduces the dilution of the nutrient value of
the compost. The compost is then ready for distribution.
As with landfilling, the major costs associated with
sludge composting relat to its dewatering, transportation to the
composting site, land purchase or lease, and operation and mainten-
ance costs for the composting operation. In addition, marketing
and distribution may be incurred by a municipality which chooses
to sell its sludge. However, it is becoming a common practice for
municipalities to give away composted sludge free of charge in order
*In this section of the report, only the static-pile or "Beltsville"
method of composting is discussed. Other approaches involving mechan-
ical digesters are also available but have not yet been widely used
in this country.
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31
to avoid these marketing costs. In so doing, the municipalities
forgo the potential revenues from the sludge. Generally, however,
marketing costs are likely to exceed the potential revenues, due
to the low market value of soil conditioning materials. We have
developed a current cost estimate for sludge composting of $80.00
to $130.00 per dry ton, including dewatering. This assumes free
distribution and no revenue from the sale of the compost.
A final land based disposal option which has been imple-
mented by only a few municipalities in this country is the heat
drying (flash drying) of sludge. Flash drying is the instantaneous
removal of moisture from solids by introducing them into a hot gas
stream. The process was first introduced in Chicago in 1932.
Today, Milwaukee, Houston, and Largo, Florida, in addition to
Chicago, heat some portion of their sludges.
Heat dried sludge generally results in a dry product
(approximately 2 to 5 percent moisture) with some nitrogen content
(generally around 5 percent) and other nutritive elements. High
quality heat dried sludge can be used alone as a low analysis fer-
tilizer; lower quality sludges are generally sold as a bulking agent
for use in the production of synthetic fertilizers. Unlike com-
posted sludge, heat dried sludge may command a market price in
excess of the costs associated with its marketing and distribution
depending upon the nitrogen content of the sludge and the transpor-
tation costs for moving it to market.
Heat drying is an expensive sludge disposal option be-
cause of fuel costs (unlike incineration, no heat value is recovered
from the sludge). It is also a highly capital-intensive process in
comparison with alternative land disposal options. Many flash
drying installations have been abandoned due to high costs, odor
problems, and air pollution and explosion problems associated with
the fine particulates.* In addition, the market acceptance of heat
dried sludge appears to be declining, thereby reducing the likeli-
hood of obtaining revenues from its sale. Gordian has estimated
the cost of sludge disposal through heat drying to be approximately
$124 to $180 per ton, including a $20 per ton credit from sales
revenues.
The outlook for the continued disposal of sewage sludge
through land application appears to be questionable at this time,
due to anticipated regulatory changes. The Resource Conservation
and Recovery Act of 1976 requires that regulations be established
*Culp/Wesner/Culp, Municipal wastewater sludge management alternatives,
-------
32
for the land disposal of sludge, including disposal by landfill.
These regulations, which are still in draft form, will restrict
the conditions under which sludge can be applied to the land, de-
pending upon such factors as soil pH, the heavy metals content of
the sludge, and the use of the land (e.g., agricultural or non-
agricultural, food chain or non-food chain, etc.). The proposed
regulations are expected soon.
In addition to federal regulatory requirements, 35 states
now impose requirements on the land disposal of sludge, or have at
least promulgated a policy regarding land disposal. These regula-
tory and policy controls range from ad hoc evaluation of individual
proposals to strict requirements for dewatering and stabilizing
sludges prior to land disposal. In some cases, the effect of these
regulations and requirments is to increase the cost of land disposal
or to introduce significant obstacles into the planning process.
Incineration. Incineration is used to dispose of approx-
imately 35 percent of the nation's sludge. In essence, incineration
is a method that divides ultimate sludge disposal between two re-
ceiving media. The oxidized organics (mostly as H?0 and CO) are
disposed of as gases into the atmosphere, while ash and particulates
from flue gases are collected and deposited in a landfill with con-
siderable reduction in the mass and volume of solids. Incineration
is the most widely used single method of sludge disposal (see Table
5). It is expected to increase in prevalence in the future, reflecting
both a growing interest in the recovery of heat value from sludge and
an anticipated trend away from landfilling.
Because of the relatively high moisture content of sludge,
incineration involves both drying and combustion. Drying is partially
accomplished by dewatering prior to incineration, but even after mech-
anical dewatering, the sludge feed to incinerators typically contains
some 60 percent to 80 percent moisture. Before solids combustion can
be complete, this moisture must be evaported. With a sludge feed of
less than about 25 percent solids (assuming not less than 60 to 65
percent volatile solids), some additional fuel is required to sus-
tain combustion in incinerators of contemporary design. As the
solids content and/or volatility increases, the requirement for
additional fuel decreases to the minimum required for start-up pur-
poses. It is important to ensure that adequate time is allowed in
the combustion cycle for moistue to be evaporated and that a certain
amount of turbulence be designed into the movement of the sludge
through the combustion unit to assist heat transfer to the moist
incoming feed.
Incineration also carries with it the possibility of air
pollution from stack gases. There is concern regarding the emissions
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33
of odors; participates; HC1, CO, SO , and NO ; toxic metals; and
organic compounds. In investigations of incinerator emissions,
EPA has concluded* that properly designed and operated inciner-
ators can achieve all presently applicable particulate emissions
standards.
In general, sludge incineration is the most expensive
form of sludge disposal. It requires a highly capital-intensive
process train, and can also entail significant fuel costs. Specific
fuel requirements are largely a function of the water and inerts
content of the sludge; incineration of a 20 percent solids filter
cake requires 6 to 10 MBtu per dry ton, whereas sludge with a 35
percent solids content is essentially autogenous (depending on
solids composition and condition). It would appear that dewatering
to 35 percent solids is desirable, however, the costs of further de-
watering the sludge to this degree may exceed the resultant fuel
savings, depending upon the scale of the plant and the particular
technology that is employed. We have estimated that the total dis-
posal costs for incinerated sludge at 20 percent solids are $130 to
$230 per dry ton. A range of $110 to $240 per dry ton is estimated
for a 35 percent filter cake.
Ocean Disposal. For seaborad communities on both the
East and West Coasts of the U.S., the ocean dumping of sewage sludge
and other waste products (demolition debris, refuse, dredge spoils,
etc.) has been an economically attractive and operationally simple
disposal alternative. It involves only the collection and barge
transport of liquid sludge to a designated point at sea where the
sludge load is discharged.
In recent years attention has been focused on the hazards
that this procedure poses to marine life, as well as the aesthetic
problems that can be created as sludge migrates toward the shore-
line with ocean current. Consequently, an EPA ban has been placed
on any further ocean dumping, with all current ocean dumping to be
ceased by 1981. Thus, the 15 percent of the nation's sludge which
is currently ocean dumped will either be applied to land or incin-
erated in the future.
2.2.2 Summary of Sludge Disposal Costs. Table 6 represents a
summary of the cost estimates for the various sludge disposal alter-
natives, with schematic diagrams of the alternative sludge process
trains shown in Figure 2. The specific methodology used in calcu-
lating costs, as well as a detailed presentation of costs for each
*U.S. EPA, Process design manual for sludge treatment and disposal.
-------
TABLE 6
SUMMARY OF SLUDdE DISPOSAL COSTS
Disposal
Alternatives t
OPTION 1:
(a)§
(b)
OPTION 2:
(a)
(b)
OPTION 3:
(a)
(b)
OPTION 4:
OPTION 5:
OPTION 6:
OPTION 7:
Capital Costs
($ x 103)
10 50
TPD TPD
3,250
5,105
4,500
6,355
4,500
6,355
2,019
2,020
3,066
1,210
10,000
11,050
11,800
12,850
13,200
14,250
6,570
6,370
9,666
4,500
100
TPD
18,500
16,350
19,500
17,350
24,500
22,350
12,700
11,600
16,633
9,200
Annual
Operating Costs
($ x 103)
10 50 100
TPD TPD TPD
730
839
747
876
836
1,045
586
485
716
460
2,781
2,821
2,412
2,556
2,688
3,232
2,001
1,673
2,834
1,705
5,118
4,765
4,295
4,151
4,995
5,451
3,713
2,794
5,198
2,978
Total Cost
($/Ton)
10 50 100
TPD TPD TPD
200
230
205
240
230
265
161
133
198
126
153 140
155 131
132 117
140 113
148 137
156 133
113 101
92 76
156 144
94 81
Revenue
Potential 10
($/Ton) TPD
200
230
205
240
230
265
161
133
20 178
126
Net Cost
($/Ton)
50
TPD
153
155
132
140
148
156
113
92
136
94
100
TPD
140
131
117
113
137
133
101
76
124
81
* Source: Gordian Associates Inc.
t All values are stated as 1978 dollars per dry ton of solids.
f Refer to Figure 2 for description of disposal options.
§ (a) refers to incineration in MHF while (b) refers to incineration in FBF.
-------
35
unit process, are included in Appendix B. These estimates are not
intended to indicate the actual costs that might be incurred by a
specific project; rather, they were developed as a general reflec-
tion of the current costs of hypothetical sludge processing trains.
Together with similar cost estimates for solid waste management
processes, these can be used for determining the kinds of solid
waste/sludge management options within which codisposal might be
economically preferable to sole-purpose facilities.
The primary source document for the cost estimates em-
ployed here is a recent study of sludge disposal options in Nassau
County, New York.* This report was selected as a reference document
for several reasons:
o The numerous reference documents dealing with sludge disposal
costs present a set of estimates that is too disparate to be
useful for comparisons. Further, the disparities in these
documents are not always evident in explicit assumptions,
making it impossible to adjust the data to standard assump-
tions.
o The Nassau County report is based on general cost functions
developed previously for EPA. These cost functions appear
to underly a number of other sources of cost data; the
curves represent as widely used a data source as any re-
viewed in connection with this study.
o The Nassau County report presents data that have been
adjusted to reflect recent (1977) cost levels on the East
Coast. These would seem to be representative of the higher
costs expected in urban areas where density and population
levels might make codisposal a potential alternative.
The estimates developed from this single source were compared
with other references. In most cases, there was general agreement.
However, a specific adjustment was made to address apparent incon-
sistencies, for example, the fuel costs of sludge incineration for
solids contents of 18 to 20 percent (typical of vacuum filtered
sludge). The adjustments were developed using various sources,
including the EPA Process Design Manual and the Culp/Wesner/Culp
report.*"* In making these adjustments, it appears that the
*Consoer, Townsend & Associates, Nassau County, N.Y. sludge management study.
**U.S. EPA, op. cit.; Culp/Wesner/Culp, op. cit.
-------
36
inconsistency in fuel usage originates with such basic sources as
the EPA cost curve,* for it was noted in a number of the sources
that used these curves.
Another point of interest is that EPA's recent studies
of historical construction cost data for sewage treatment plants
indicate that for most sludge handling unit processes, there are
diseconomies of scale. This contradicts the economies of scale
shown in Table 6. However, it is felt that the diseconomies noted
in EPA's analysis are idiosyncracies of the statistical analysis,
rather than significant findings from the data sample.
2.3 Codisposal Processes
The primary purpose of this discussion is to provide an overview
of the currently practiced methods of disposing of municipal solid
waste (MSW) and municipal sewage sludge (MSS) simultaneously, in
the same place and/or manner. The emphasis is on understanding how
the two waste streams combine, and on identifying what the union
means in terms of process steps or costs that can be eliminated or
in terms of new technology required. In this section, the most
viable codisposal processes are described. The following section
addresses costs and other economic considerations.
One of the fundamental assumptions used here is that the sewage
sludge is of a standard nature. Sludge can vary widely in chemical
composition and its percentage of volatiles, depending on influent
characteristics and on the means of treatment. For the purposes of
this report, it is assumed that the sludge derives from general
residential sources (as opposed to specialized industries) and that
it is a mixture of primary and waste activated sludge with 70 per-
cnet volatile solids. Similarly, the solid waste is assumed to repre-
sent the generally accepted average characteristics of 5000 Btus per
lb., 150/yd density, and 75 percent combustible (weight) with 20
percent moisture as received.
Further assumptions must be made concerning the transporting
distances for MSW and MSS in order to develop generalized systems
for comparison. Except for solid waste landfilling, if the codis-
posal process is primarily for MSW disposal, the sludge is assumed
to be pumped in a pipeline at 4 to 6 percent solids to the site.
For a landfill, the sludge may well be trucked to the site. If the
process is basically for sludge disposal, then any MSW processing
*U.S. EPA, Areawide assessment procedures manual, Appendix H.
-------
37
facility is assumed to be co-located. These assumptions are based
on the premise that MSW must be collected by a vehicle in any case
and therefore it can be re-routed more easily.
A final important assumption concerns the ratios at which MSW
and MSS quantities will realistically combine. The viable set of
ratios will determine how the two waste streams, with their respec-
tive territorial boundaries and component populations, can fit to-
gether, if at all. One point to consider is the ratio of the solid
waste and sludge generated from equivalent populations. Generally
accepted daily generation rates of 2.5 dry Ibs. of MSW (3.3 Ibs.,
as received) and 0.2 Ibs. of dry sludge solids per capita are equiv-
alent to a ratio of 13 parts of MSW to one part of MSS. This ratio
is considered for each codisposal alternative presented in this
study whenever it proves feasible. However, for several of the
processes discussed, operating at the ratio is not realistic.
Further, it is often impractical to consider wastes from equivalent
populations because of political or institutional factors.* For
these reasons, this study does not limit the discussion of MSW:MSS
ratios to equivalent populations, but instead stresses the quantity
constraints imposed by the technology of the codisposal processes
themselves. As a result, each of the systems examined in the
following section will be discussed in terms of its own optimal
ratio as well as the ratio of equivalent populations for reference.
A summary of the refuse to sludge ratios is presented in Figure 3.
2.3.1 Codisposal in a Sanitary Landfill. Figure A presents a
generalized flow chart for codisposing MSS and MSW in a sanitary
landfill. The techniques employed depend upon the nature of the
sludge. If thickened (four to eight percent solids) sludge is
used, it may be piped or trucked to the landfill site and sprayed
onto a layer of solid waste. This mixture is then covered with a
layer of soil. The procedure is the same for dewatered sludge (20
percent solids) except that it will have been transported by truck
and spread by machine. Both approaches require that the sludge be
stablized by digestion as a first step in handling. The most im-
portant difference between the two sludge landfilling methods is
in the ratio of sludge to solid waste, based on the absorptive capa-
city of the refuse. The results of the Oceanside, California** de-
monstration project indicate that one pound of solid waste can absorb
O.A to 2.1 Ibs. of sludge (5 percent solids). However, the report
concludes that in order to provide a margin of safety against leachate
*See Chapter 3 for a detailed discussion of this matter
**Stone, Disposal of sewage sludge into a sanitary landfill.
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38
Codisposal Options
Landfill
Incineration
Composting
MHF/FBFt
Waterwall
Dedicated Boiler
Modular Incinerator
Pyrolysis
Wet Weight
Ratio (MSW:MSS)
optimum range
10:1 5:1 3:1 2:1
r \ ir
1:1 1:2 1:3 1:5 1:10
Figure 3. Refuse to sludge ratios for major codisposal options.
* Vertical dashed line represents combined waste stream (MSS & MSW)
generated by equivalent populations (13:1 dry weight ratio of MSW to MSS)
using 20% solids MSS.
tNote that these codisposal options employ RDF instead of raw MSW.
RDF is 75% (by weight) of incoming MSW. The scales and ratios shown here
are all for raw MSW plus MSS only.
-------
Optional
Dewatering
Landfill
• Spreading
• Covering
• Compacting
Figure 4. Landfill codisposal.
-------
problems, a ratio of 40 Ibs. of MSW to 1 Ib. of sludge (dry weight)
is desirable for sludge at 5 percent solids. If dewatered (20 percent
solids) sludge is used, the safe ratio translates to 10 Ibs. solid
waste for every one Ib. of sludge (dry weight). This safety margin
is designed to accommodate natural precipitation, but in wet climates
or following periods of heavy rainfall, application rates may have
to be adjusted. If these rations are not exceeded, it appears that
leachate problems arising specifically from the inclusion of sludge
in a solid waste sanitary landfill may be avoided.
The dry weight ratio of MSW generation to MSS generation
for equivalent populations is 13:1. Therefore,it can be seen that
liquid sludge will combine with refuse at a ratio that implies
either a larger MSW population base or only a partial solution to
sludge disposal. These conditions might describe the situation where
a regional landfill accommodates the solid waste disposal needs of
a large geographical area, but only a small, centralized population
is served by a sewage treatment plant. It might also apply in cases
where industrial sludge is the potential candidate for codisposal,
provided that the sludge does not contain hazardous waste products.
Dewatering the sludge to 20 percent soldis will increase
the ratio beyond the point of equivalent populations, so that a
larger sludge producing population can be accommodated. At this
level, the landfill could handle all of the sludge from the solid
waste generating population with some additional safety margin.
This additional flexibility would apply in situations where more
than one landfill is serving an area, raising the possibility that
just the site closest to any waste water treatment plant could handle
all of its dewatered sludge.
Landfilling as a codisposal option has several potential
benefits. It eliminates the need for any additional sites or facil-
ities for separate sludge disposal. It has been reported that the
increased moisture in the fill reduces vector problems and aids in
the control of blowing litter. Where undigested and/or primary
sludge is used, it may also increase methane generation, thereby
improving the site's potential for energy recovery. If the sludge
spreading operation is well designed, there should not be any appre-
ciable rise in the operating costs of the landfill. For those commun-
ities that are not facing a shortage of permitted landfill space and
where hauling costs are not prohibitive, this may well be the most
attractive codisposal option.
Any of the landfilling codisposal options will be signif-
icantly affected by the RCRA guidelines being drafted by EPA. The
preliminary signals from EPA indicate that most sewage sludge will
be regarded as non-hazardous waste which will be subject to the
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41
recently published RCRA section 4004 landfill criteria rather than
the RCRA subtitle C, hazardous wastes regulations. Final Federal
regulations are expected in early 1980.
2.3.2 Codisposal in Coventional MSW Incinerators. Conventional,
refractory walled solid waste incinerators without heat recovery
exist in many major cities as a means of reducing the volume of the
MSW that must be landfilled. For such cities, the coincineration of
MSS with refuse could be a codisposal option. The process describes
here is a generalized, theoretical approach drawing upon engineering
principles discussed in Weston's report and elsewhere.* This dis-
cussion is intended merely to provide a preliminary knowledge of the
more important principles involved in the coincineration of refuse
and sludge. Past experimentation with coincineration has led to the
conclusion that sludge must be partially dried in order to achieve
successful combustion. The sludge is dewatered to 20 percent solids
and then fed into a direct drier heated by hot flue gases from the
MSW incinerator. The dried sludge is blown into the incinerator's
combustion chamber along with exhaust gases from the drier. Before
the moist exhaust gases from the drier are released to the atmosphere,
they are heated to 1400°F to destroy odors. Residues are removed
as usual and landfilled.
This coincineration process is shown in Figure 5. The
most important variables in the system are the nature of the sludge
(percent volatiles versus ash) and the type of drier utilized. The
volatility of the sludge determines its Btu content as well as the
quantity of ash left as residue after combustion. The heat transfer
efficiency of the drier is also critical in determining the possible
ratio of MSW to MSS.
There are severable notable exceptions to this process.
The coincineration facility in Norwalk, Connecticut and a planned
facility for Glen Cove, New York, employ different drying techniques.
In their approach, dewatered sludge (20 percent solids) is sprayed
onto the MSW as it feeds into the combustion grate. The residence
period during combustion is designed to be of sufficnet length to
evaporate the moisture to the point where the sludge will combust.
An essential consideration with any of the approaches to
coincineration is the requirement for heating the moisture-laden drier
*An excellent discussion of the thermodynamics of combined sludge
and refuse incineration is provided in Klaus Feindler's paper on
the Krefeld, Germany codisposal plant. This paper is included
as Appendix D to this report.
-------
Dewataring
MSW
Incineration
(Refractory or
Starved
Air Modular)
Dryer
Ash to
'Landfill
Figure 5. Cbincineration of MSS with solid waste (no energy recovery).
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43
exhaust gases to the point where odor causing organics are destroyed.
A temperature of 1400°F is necessary to accomplish this. Thus, the
entire coincineration process must generate enough energy to dry the
sludge, sustain thorough combustion of refuse and sludge, and raise
the furnace exit gas temperature to 1400°F. According to the 1976
Weston Engineering study, the key to maintain this energy balance
is the moisture content of the input mix of MSS and MSW. The re-
sults of that study indicate that for typical refractory lined in-
cinerators, a total (MSW plus MSS) input moisture content of not
more than 50 percent must be maintained.
With this requirement, the refuse to sludge ratio for typ-
ical MSW (80 percent solids) and vacuum filtered (20 percent solids')
MSS ranges from a minimum of four parts solid waste to one part
sludge (on a dry weight basis) up to any higher proportion of MSW.
The equivalent population ratio of 13:1 (MSW to MSS) is well within
this range, even when a reasonable allowance for variation in refuse
moisture content is included. The basic ratio (4:1) allows for a
larger sludge generating population than MSW base, which is well
suited to the idea of multiple incinerator sites with the one closest
to the sewage treatment plant able to accommodate all of the sludge.
There are several potential considerations related to the
widespread implementation of coincineration. One is the possibility
of air pollution emission problems. Sludge incineration will con-
tribute additional trace metals or particulate pollutants. A related
difficulty is that the inert components of the sludge may become con-
centrated in the ash. If trace metals are present in the sludge ash,
the concentrations may become high enough to cause the residue to
be classified as a hazardous waste, with concomitant problems in
landfilling of the final residues. These are issues that would be
examined and resolved on a case-by-case basis and consequently are
not dealt with in this generalized process discussion.
2.3.3 Codisposal in a Sludge Composting Operation. Composting
MSS to produce a stable soil conditioner is gaining popularity in
communities considering alternative sludge disposal options. MSW
alone has been tried in the past without much success in this coun-
try, although in Europe, there are numerous succesful plants. The
combination of sludge and refuse in a composting operation can be
considered a technically proven process which merits discussion.*
*There are several continuing problems with composting such as
fungus growth,but the process has been operational for some time
in Altoona, Pennsylvania and in several European installations.
-------
The basic composting system is shown in Figure 6. The
MSS process is unchanged from the previously described, sludge-only
composting approach, except that processed solid waste is added as
a bulking agent instead of wood chips. The raw MSW must undergo
considerable processing in order to produce a marketable composted
product. Obviously, most non-organics should be removed from the
solid waste stream. The representative system described here em-
ploys a full recovery front end processing train to separate ferrous
metals, aluminum and glass; it would produce an RDF-like material
for use in the composting system. The solid waste processing system
is assumed to be co-located with the sludge composting operation.
Dewatered sludge may be trucked to the site.
There are currently two main variations in the composting
technique, both of which have proven feasible in the U.S. on a demon-
stration scale. One is the forced aeration static pile approach
developed at the USDA Agricultural Research Center in Beltsville,
Maryland. In this approach sludge and wood chips are mixed and
spread in a pile over a pipe configuration which employs a blower
to draw air through the pile, thus speeding digestion and elimin-
ating the need for turning. The second approach utilizes a large
enclosed mechanical digester to speed the stabilization process.
The digester systems are also based on air being forced through
the compost mixture, in this case through rotating auger-like arms
which also help mix the sludge and bulking material. Mechanical
systems are fairly widespread in Europe and a mechanical digester
has been operating in Altoona, Pennsylvania for several years.
Both of these systems require that the mixture to be
composted contain 40 to 60 percent moisture for optimal efficiency.
For systems using wood chips and vacuum filtered sludge (20 percent
solids), the recommended ratio is three parts bulking agent to one
part sludge (by volume). If processed MSW is used (at 80 percent
solids), it would combine at a 1:1 (MSW to MSS) wet ratio or a 4:1
ratio by dry weight. Since processed refuse represents about 75
percent of the weight of raw MSW, the maximum total ratio of MSW to
MSS is 5.3:1. This blending ratio still falls short of the 13:1
mix produced by equivalent populations, indicating that composting
can provide only a partial solution ot the solid waste disposal
problem.
Tests have show that these composting methods are capable
of accommodating raw sludge at 5 percent solids. In fact, at least
one of the mechanical processes (Fairfield) claims to work best with
that mixture. Results of experiments conducted at Beltsville, and
with the Fairfield mechanical digester at Altonna, show that carefully
designed compost systems are capabile of containing the odor and
pathogen problems associated with undigested liquid sludge. Using
-------
MSW
Processing
Sludge
Input
h_
w
Transport
Composting
Process
Product Storage
and
Marketing
Optional
Dewatering
Figure 6. Codisposal through composting.
t_n
-------
46
five percent solid sludge would tend to eliminate the cost of
sludge dewatering, but it would also result in a substantial in-
crease in the amount of bulking agent required. Since the cost
of wood chips is increasing (Beltsville recently tripled), an
approach employing a refuse derived bulking agent appears attrac-
tive. Contrary to expectations, however, the processed refuse is
very costly in itself to produce. Cost trade offs result which are
examined later in Section 2.4.
Codisposal through composting carries the same funda-
mental problem attendant to sludge composting: a questionable
market for the end product, especially in view of pending EPA
restrictions on the end use of sludges. In addition, the via-
bility of processed refuse as a bulking agent is not clear. Re-
searchers at the Beltsville facility feel that pelletized RDF may
be more suitable, but this entails further processing and expense.
2.3.4 Codisposal in a Multiple Hearth or Fluidized Bed Sludge
Incinerator. This approach has been the focus of much recent in-
terest in codisposal with projects planned in Contra Costa County,
California, and Memphis, Tennessee, and a facility in Duluth, Minne-
sota in final shakedown. For single purpose sludge disposal,
multiple hearth furnaces (MHFs) and fluidized bed furnaces (FBFs)
typically burn fossil fuel to evaporate the moisture from the de-
watered sludge (20 to 40 percent solids) to the point of self-
sustaining combustion. For codisposal, the system is essentially
the same except that processed MSW is used as the fuel. For both
types of furnace, the raw MSW must be passed through an RDF processing
train, which can recover materials for resale and produces combus-
tible shreds with a 3" to 6" particle size. For a multiple hearth
furnace, processed refuse and dewatered sludge can be mixed prior
to injection into the upper hearth or they may be fed in separately,
with sludge entering the upper levels and refuse entering the middle
hearths. Processed refuse and dewatered sludge may also be injected
together or separately into an FBF. The basic systems of these two
processes are depicted in Figure 7.
The use of thickened sludge as the input is theoretically
possible for both furnace types. However, technical considerations,
such as the huge hearth area required, make that approach impractical
in many existing furnaces. Several recent tests suggest that optimum
efficiency is obtained when the waste input (RDF+MSS) is a mixture
that is 30 to 40 percent solids.* This translates to a dry weight,
*A Review of Techniques for Incineration of Sewage Sludge with Solid
Wastes, Roy F. Weston, Inc., December 1976 pp. 67-76 and personal
communication with Terry Allen, Envir. Tech Engineering.
-------
Raw
MSW
>,
RDF
Process
_ i
r
*-
Transport
i
r
Materials
Recovery
MHF
FBF
Starved Air Mode
Optional
Dewatering
Ash to
-> Landfill
Hot
Gases
Waste Heat
Boiler
Gaseous
^.Effluents
to APC Device
Figure 7. Multiple hearth or fluidized bed coincineration.
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48
raw MSW to MSS ratio that ranges from 1:1 to 3:1. Since equivalent
populations generate these wastes on a 13:1 dry basis, this codis-
posal option may provide only a partial solution to the solid waste
disposal problem. Either a large portion of the RDF roust be sold
elsewhere, extra combustion capacity must be built, or the MSW
processing facility must be built on a smaller scale to accomodate
only a portion of the waste. With the high capital costs and dis-
tinct economies of scale in RDF processing, these three options
present some tradeoffs, which are discussed in the next section.
It is interesting to note that the Contra Costa facility includes
extra capacity for RDF combustion. In Duluth the codisposal facil-
ity is not planned to handle the entire regional MSW flow until
additional RDF markets are found.
There is an alternative approach to codisposal in an
MHF, where the furnace is operated in a pyrolysis mode. • The
process is the same as combustion except that the incoming air
is reduced to be below stoichiometric proportions; the gas re-
sulting from pyrolysis of the mixed feed has a heat value of up to
130 Btu per sdcf. This pyrolytic gas is suitable for combustion
in an afterburner and may be suitable for combustion in an ex-
isting boiler or furnace as a means of energy recovery. The MSW
and MSS ratio is basically unchanged for this mode of operation,
although slightly higher moisture percentages appear possible
(up to 60 percent) as air requirements are reduced.* This approach
has been tested briefly at a pilot facility at the Constra Costa
project. The limited success of the initial testing has led to
plans for a larger facility there.
It should be noted that, based on experiences in Europe
and Contra Costa, EPA now feels that coincineration in an MHF
under pyrolysis conditions is the preferred approach.**
Fluidized bed codisposal has been successfully demon-
strated at the EPA supported demonstration hydra-pulping facility
in Franklin, Ohio. The 400 TPD facility in Duluth which will co-
dispose of RDF and MSS in two fluidized bed furnaces is now in
the final shakedown phase.
*Incineration-Pyrolysis of Waste Water Treatment Plant Sludges,
R.B. Sieger and P.M. Maroney (Brown & Caldwell) U.S. EPA 1977.
**Sludge Treatment and Disposal; Sludge Disposal, (U.S. EPA Tech-
nology Transfer series), Vol. 2, EPA - 625/4-78/012, October 1978,
pp. 23-24.
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49
All of the MHF/FBF codisposal systems currently planned
in the U.S. incorporate some form of energy recovery, usually
through waste heat boilers which capture the heat contained in
hot exit gases and transform it into steam.
It is also possible to retrofit existing multiple
hearth and fluidized bed furnaces to accommodate RDF. The main
modification required is adapting the feed system to accommodate
RDF. The Contra Costa facility was retrofitted and the major
MHF manufacturers feel that their furnaces can be easily adapted
to codisposal.*
2.3.5 Codisposal in an MSW Waterwall Combustion Furnace.
Widespread experience in Europe has shown that incineration of
MSW and MSS in a mass burning waterwall furnace with heat recovery
is a technically proven and even reliable method of codisposal.
The sludge handling approach employed in the European
codisposal facilities encompasses a wide variety of technologies,
ranging from indirect dryers using thickened sludge (4 percent
solids as input - Dieppe, France) to direct dryers using dewatered
sludge (25 percent solids - Lefeld , Germany).** The system which
will be described here is a representative one, designed to illus-
trate general materials flow and some of the more important issues.
It is not intended to represent the "best" or even most prevalent
approach, since the merits of the alternative processes are still
very much in debate.
A representative system, shown in Figure 8, is similar
to the solid waste only combustion process discussed earlier. As
a mass burning system, preprocessing of the MSW is not required.
The sludge input, which can be pumped or trucked to the incinerator
site as a liquid, is dewatered (20 percent solids) and fed into a
steam-heated drier. (Note that it is also possible to use a direct
drier employing hot fine gases.) When it has been dried to 85
percent solids, it is then fired in the combustion chamber.
The system designated for this analysis uses an indirect
drier heated by steam as opposed to the direct drying method, where
hot flue gases intermingle directly with the sludge.
*Richards, D. and Gershman, H., The conversion of existing muni-
cipal sludge incinerators for codisposal.
**For a detailed explanation of European approahces see European
Refuse Fired Energy Systems, Vol. 2, U.S. EPA, SW 176C.1, 1979
-------
Dewatering
Steam
Ash to
'Landfill
Recovered
Energy
Figure 8. Codisposal in a waterwall combustion furnace.
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51
There are currently a number of different driers capable
of handling this technique. Much of the technology has been de-
veloped in the food preparation industry. Among the driers currently
in use are the jacketed or hollow-flight type, wiped-surface evap-
orators (widely used in Europe), and jacketed or steam-tube rotary
driers. Some of the driers now in use recycle a portion of the
previously dried sludge for use as an admixture to the incoming
dewatered sludge, producing a 50 percent solids in-feed which
exits the drier at about 85 percent solids. Drying thickened
sludge (4 percent solids) is impractical for some drying approaches
due to the energy demands of such a wet mixture and the potential
for fouling of the drying surface, although, as noted earlier, the
system at Dieppe operates using thickened sludge. Weston estimates
that using 20 percent solids sludge as input to the codisposal sys-
tem, at equivalent population input rates, some 15 percent of the
boiler output will be consumed for sludge drying. The remaining
steam (as well as steam generated by sludge combustion) is avail-
able as a potential source of revenue.
The ratio of refuse to sludge is likely to be limited in
this case by practical and economic, rather than technical, consid-
erations. For many systems, sludge drying is a net consumer of
steam, even considering the steam regained when the dried sludge
is burned. However, this is not always the case, the Krefeld sys-
tem being a notable exception. Outside steam sales are a critical
revenue source in the finances of waterwall combustion units,and the
loss of saleable steam output through sludge drying will reduce the
quantity available to supply outside demands. Even though the steam
used for sludge drying would itself be sold, steam sales to the
major users typically sought after for energy recovery projects in-
volve large volumes of available steam. For those codisposal sys-
tems which involve reduction in the steam output of existing or
planned MSW only facilities, pinning down markets in advari'.i assumes
even greater importance. For the purpose of this analys:,-, 3nly
ratios greater than ten parts of MSW to one part of sludgt. .iave been
considered, in order to ensure that there would be sufficient steam
output regardless of the sludge drying approach.
Despite the spread of waterwall combustion MSW incin-
erators in this country, only one system currently incorporates
sludge disposal (Harrisburg, Pennsylvana). However, several other
communities are considering this approach. The fact that codisposal
waterwall applications are not further advanced in the U.S. is not
the fault of technology but rather the consequence of institutional
contraints.
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52
2.3.6 Codisposal in an MSW Dedicated Boiler System. Dedicated
boiler systems are gaining popularity as an MSW disposal option.
Large new facilities are being constructed in Akron, Ohio and
Niagara Falls, New York. While neither of these facilities currently
plans to include sludge disposal, dedicated boilers should be compat-
ible with codisposal in principle. The basic system, depicted in
Figure 9, is fundamentally the same as the previously described
waterwall system except that the incoming MSW is processed into RDF
before entering the combustion chamber. The input sludge may be
dried via direct or indirect drying, depending upon the ease of
adaptability, thermodynamics, and economics of the specific system.
The most significant differences between this system and
the waterwall system lie in the higher costs and increased revenue
potential of the dedicated boiler, both of which relate to the higher
energy transfer efficiencies of the semi-suspension combustion unit.
With limited data it is not possible to comment definitely on such
a codisposal system. Refuse to sludge dry weight ratios would not
vary appreciably from those explained earlier for direct and indi-
rect drying except that, since RDF instead of raw MSW is being
added, the minimum proportion of refuse to sludge would increase.
2.3.7 Codisposal in an MSW Modular Incinerator. Thermal co-
disposal in a modular incinerator (as shown in Figure 10) differs
from other incinerator-based systems only in scale. The process is
essentially a solid waste mass burner with the capability for either
direct sludge drying, or indirect drying when the system is equipped
with a waste heat boiler. There are currently no codisposal modular
incinerator facilities but, according to system vendors, the process
is feasible. Coburning sludge and refuse is currently being tested
at the Consumat Facility in North Little Rock and the unit under
construction in Auburn, Maine includes plans for industrial sludge
incineration.
One consideration for codisposal in modular incinerator
systems is that the fairly low energy transfer efficiency of the
combustion unit would affect refuse to sludge ratios. If energy
recovery is involved, the amount of energy left over from sludge
drying would also be less than for waterwall systems. MSW to MSS
ratios could range upward from 3:1 (dry weight), although at that
level there is not much allowance for the considerable moisture
variability that occurs in the input refuse stream. Mixture at
the generation ratio of equivalent populations (13:1) would be more
desirable.
-------
Raw
MSW
Materials
Recovery
Boiler
Ash to
"Landfill
Dewatering
Recovered
Energy
Steam
Figure 9. Codisposal in a dedicated boiler system.
OJ
-------
Combustion
Unit
Dewaterin
Ash to
•> Landfill
Recovered
Energy
Figure 10. Codisposal in a modular combustion unit.
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55
2.3.8 Codisposal in an MSW Pyrolysis System. Pyrolysis may be
be used for the disposal of either MSW or MSS. The major sludge
pyrolysis codisposal system has already been discussed in the
multiple hearth furnace section. This section will discuss codis-
posal in developmental pyrolysis systems that are primarily for
the disposal of MSW. The generalized system is presented in
Figure 11. This system assumes a representative pyrolysis approach,
synthesized from the four major processes currently under develop-
ment (Purox, Torrax, "Flash" pyrolysis, and the LANDGARD System).
Most of the systems require some degree of MSW processing (except
Torrax) prior to MSW entering the pyrolitic chamber. The MSW pro-
cessing train is assumed to be co-located with the pyrolysis unit
and the sludge is assumed to be piped in and dewatered to 20 per-
cent solids at the site. The fundamental concept of using heat
from the thermal disposal of M3W tc dry the sludge remains unchanged.
The unique features of pyrolysis are the reduced air
requirements and the fact that the thermal decomposition process
is endothermic rather than exothermic - in theory, there is no com-
bustion at all. A distinct advantage of this approach is that the
product of pyrolysis is a transportable fuel (either gas or oil) of
low to medium Btu value which appears to be adaptable to existing
fossil fuel firing systems. The addition of sludge to the system
poses several problems. The major difficulty is that moisture in
the sludge results in dilution of the end fuel product, lowering
the overall Btu value. Further , drying the sludge consumes what
would otherwise be exportable energy. If a direct drying system
is used, an after burner may be necessary to destroy the odoriferous,
moisture-laden drier exit gas, since its introduction into the py-
rolysis chamber would be detrimental to the pyrolysis process and
to the final fuel quality. The use of an indirect drier would re-
quire the addition of a waste heat boiler which would also drain
saleable energy. There is a fundamental trade-off here, as in
all of the energy-recovery systems, between selling recovered energy
to an outside user and utilizing it for the drying of sludge. How-
ever, the successful European experience indicates that, under certain
conditions and using proven technologies, energy recovery can be
compatible with coincineration.
The refuse to sludge mixture ratios for copyrolysis are
similar to the other thermal disposal alternatives. Historical data
are non-existent (although both the Torrax and Purox systems have
demonstrated technical feasibility), but Weston notes that for the
Torrax system the input mixture should be at least 45 percent solids;
while for the Purox process, the solids content can dropt to as low
as 35 percent. These figures correspond to dry weight ratios of
4:1 (MSW to 20 percent solids MSS) and 3:1 (?J)F to 20 percent solids
MSS) respectively. Both systems would easily accommodate waste
streams from equivalent populations.
-------
MSW
Processing
Heat or
Fuel for
Drying
Fuel or
Energy
Recovery
Residue to
Landfill
or Resale
Sludge
Input
t
Transport
^
Dewatering
w
Sludge
Dryer
Figure 11. Copyrolysis.
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57
Pyrolysis systems which produce only a fuel and do not
combust it to produce steam or drier heat should have little diffi-
culty in meeting air quality standards. Many of the potential
pollutants are contained in the fuel itself and scrubber or bag-
house filters should be capable of cleaning any remaining particu-
lates from the in-house system exhausts. However, the addition of
sludge to the system, with the requirement for fuel combustion in
some form for drying, may necessitate more costly emission control
equipment. Until full-scale facilities begin operation, many of
these issues will remain unresolved and this technology should be
considered developmental.
2.3.9 Summary and Conclusions. Eight of the more promising
codisposal alternatives have been briefly examined here. Within
certain mixing ration constraints, all are technically feasible,
although none (except for landfilling) have been demonstrated in
this country on a full production basis. Each system has both ad-
vantages and disadvantages, depending on the specific circumstances
in which it is applied. One conclusion that is readily apparent
from the analyses conducted in this report is the need for more
empirical data concerning the actual processes. However, there are
several other useful conclusions to be drawn from the data on hand.
The first is that, while landfill codisposal is one of
the least expensive and most proven systems, the fact that it re-
duces rather than extends landfill life diminishes its problem-
solving potential in the urban areas that are the most likely to
have sludge and solid waste problems in combination. Consequently,
landfill codisposal will not be emphasized in this study.
A further distinction is that several of these techniques
are very compatible with existing facilities. Retrofitting existing
MHF or FBF sludge incineration systems has been demonstrated and
warrants further study in view of the large number of such furnaces
currently in use. The solid waste thermal disposal systems can also
be adapted relatively easily to handle sludge as well. However, all
of the systems are more economical if originally desined for the
purpose of codisposal.
Six of the eight processes are based on systems designed
primarily for the disposal of MSW. MHF/FBF and composting are the
only ones that are essentially sludge disposal oriented. For the
MSS disposal systems, solid waste is employed as a replacement for
an ingredient in the disposal process (i.e., bulking agent or fossil
fuel), while for the MSW-based processes sludge disposal is an
energy consuming, addition which has the potential to increase
pollution control problems. On the other hand, the inclusion of
sludge disposal in MSW systems may provide a built-in source of
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58
recovered energy revenues as well as possibility of partial Federal
funding for facility construction under the Construction Grants
provisions of the Clean Water Act. These distinctions are impor-
tant from the cost allocation point of view, which will be discussed
in the following section.
Landfilling and composting are the only viable non-thermal
based processes, although composting involves many uncertainties.
The main questions concern the quality of the product, the compati-
bility of MSW as a bulking agent, the effect of pending EPA regu-
lations, and especially, the availability of a market for the pro-
duct. Of the thermal codisposal options, copyrolysis is the most un-
proven. This situation stems directily from the as yet unresolved
technological problems of the underlying MSW pyrolysis process.
However, pyrolysis via MHF sludge incinerators appears promising
as does coincineration in MSW waterwall or dedicated boiler systems.
The two systems with the most potential at present are
the MHF/pyrolysis coincineration option as tested in Contra Costa
County, California and the waterwall mass burning combustion process
along the lines of the systems in Harrisburg, Pennsylvania and num-
erous European locations. These systems will be examined in more
detail in the follox^ing chapter.
2.4 Economics of Codisposal
This section will examine the relative costs of specific Co-
disposal systems as compared to alternative codisposal options.
Again, due to the general nature of this analysis, no attempt is
made to present these costs in detail. However, it is apparent that
economics may be the pivotal argument in the decision of whether to
commit to a codisposal process or to single purpose facilities.
Therefore, the data developed here are presented to enable commun-
ity decision makers to evaluate relative levels of cost for several
different scale systems and to determine which approach, if any, is
applicable to their specific needs. A brief general discussion of
the economic trade-offs between solid waste and wastewater agencies
is also presented.
The economics of each codisposal process are presented through
the same general format. Two codisposal facilities are compared,
a large and a small (TPD capacity), based on the feed ratios and
moisture contents developed earlier. For those approaches which
are constrained to narrow ranges of compatibility ratios, only one
scale facility will be examined. Costs are broken down by source;
those attributable to the MSW processing, the MSS processing, or
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59
those "other costs" not directly linked to either process. The
most commonly encountered "other cost" arises from the need for
additional sludge drying before it can be introduced to the solid
waste-based thermal disposal process. The costs for direct and
indirect sludge driers are based on the data developed in the
Weston study.
Capital and annual costs for the individual waste processing
streams are based on the figures developed earlier for single
purpose systems. However, these costs are adjusted when the co-
disposal approach involves savings or additional costs as noted
in the specific process descriptions to follow.
For most solid waste based systems, a general additional
cost is incurred by the requirement to transport the sludge to
the site although with sufficient planning the wastewater treat-
ment plant and solid waste disposal facility can be coloacted.
The two major means of transporting sludge are by truck or by
pumping through a pipeline. Rail and barge transportation are
also feasible alternatives, but their applicability is so limited
that they will not be considered here. transporting by truck is
more economical after the sludge has undergone dewatering, either
to 20 percent or 40 percent soldis. Dump trucks are the commonly
employed vehicle. Costs for an 80 TPD (dry weight) facility run
$1.20 per dry ton mile based on an average 10 mile trip,* including
capital costs.
In order to be pumped through a pipeline, sludge must be re-
latively liquid (no more than 5 percent solids). Pipeline capital
costs are high but operating costs are small and the unit costs are,
therefore, very sensitive to economies of scale. Total capital and
operating costs for this approach range from $0.60 to $3.10 per
dry ton (10 to 100 TPD) depending on the scale of the operation.
Corresponding capital costs range from $100,000 to $200,000 per dry
ton mile. An average pumping distance of 10 miles is also assumed;
resulting in a total transportation cost of from $6.00 to $31.00
per dry ton of sludge, with capital costs of $1-2 million. As
noted in an earlier section, this evaluation assumes dewatering to
20 percent at the codisposal site and transportation to that facility
via pipeline for all codisposal options unless otherwise noted.
Perhaps the most important economic issue in the minds of many
officials is the extent of federal funding available to codisposal
projects under the Construction Grants (Sec. 201) provisions of
PL 92-500. Some confusion has been generated by EPA's disparate
*Consoer, Townsend, op. cit.
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60
handling of two current codisposal projects. For Contra Costa
County, only those aspects of the solid waste processing which
directly contributed to the MSS incineration process were con-
sidered eligible for grant money. In Duluth the entire project,
including the RDF facility, was determined eligible. EPA, how-
ever, has stated that the Minnesota project is the exception and
that future codisposal projects will receive funding according to
a specific formula discussed in Chapter 3.
2.4.1 Landfilling. According to the ratios determined earlier,
dewatered 20 percent solids sludge can be safely added to solid
waste in a sanitary landfill at a dry weight ratio of one part MSS
for 10 parts MSW. Accordingly, the costs presented here are for
landfill codisposal facilities combining 100 tons of MSW with 10
dry tons MSS and 1000 tons MSW with 100 dry tons MSS. This ratio
comes close to the equivalent population generation rate (13:1)
and is representative of communities with populations in the range
of 75,000 to 100,000 and 750,000 to 1,000,000, respectively.
The cost breakdowns for this approach are shown in
Table 7. Capital and operating costs attributable to the solid
waste process are unchanged from the single purpose system. The
sludge related costs are based on aerobic digestion, dewatering
to 20 percent solids via vacuum filtration, and truck transporta-
tion to the fill site. In Table 7 the costs for co-landfilling
MSW with stabilized (aerobically digested) thickened sludge are
shown. This approach eliminates the expense of dewatering. How-
ever, it is unclear at this writing whether the addition of 5
percent solids MSS will be economical in view of the potentially
stringent requirements of pending RCRA guidelines.
According to the Oceanside, California data, the addi-
tion of sludge to the MSW sanitary landfill does not significantly
increase operating costs. Therefore, no additional landfilling
costs are included in the sludge processing train. However, it
should be noted that pending EPA sludge disposal guidelines have
the potential to substantially increase the costs of codisposal in
an MSW sanitary landfill. At this writing, any attempt to specify
the amount of increase would be speculative, so no additional costs
have been presented for this process. It is apparent that as a
result of the recently published RCRA landfill criteria, the annual,
and especially capital, costs of landfilling in general (including
codisposal) will be greater than is shown here.
The potential for savings with this approach over single
purpose landfilling stems from the elimination of a separate land-
fill facility with its attendant capital costs and institutional
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61
obstacles. Also, annual costs are reduced by the smaller capital
amortization costs and reduced operating costs. Clearly, no
matter what the implications the RCRA guidelines, landfill codis-
posal should be considered as a viable sludge disposal alternative
in areas where land is available.
2.4.2 Conventional Coincineration. The costs shown in Table i
reflect the costs of constructing and operating a refractory wall
MSW incinerator without heat recovery, fitted with a rotary drum
type direct dryer to accommodate dewatered (20 percent solids) MSS,
The large and small capacities are both shown at a 10:1 MSW to MSS
ratio which approximates the equivalent population ratio and main-
tians autogenous combustion.
Major MSS expenses stem for dewatering and transport.
MSW costs are unchaned from those of single-purpose facilities.
It should be noted that increased costs due to more extensive
residue handling and emissions control equipment are not included
here. Measurements at the Krefeld plant indicate that the addi-
tion of sludge in refuse fired incinerators will significantly
increase particulate emissions.
2.4.3 Composting Codisposal. The economics for the two major
composting approahces are shown in Table 9. Part "a" of this
table covers the static pile process, employing processed MSW with
dewatered sludge in a 5:1 ratio. The individual costs are identi-
cal to the single purpose MSW (RDF) and MSS (composting) costs
except that $10 per dry ton has been deducted from ithe MSS cost
of composting to account for the replacement of wood chips with
RDF as bulking agent.
The key to the economics of this system is that RDF is
relatively expensive to produce, and using it as a replacement for
a low value input such as wood chips is not an economical prospect.
RDF combines the dry sludge at a 4:1 ratio so that, at this scale,
the RDF bulking agent costs $100 per dry ton of MSS, vs. $10 for
wood chips. Since RDF has a potential revenue value of $6/ton as
an alternative fuel product, the opportunity cost of each dry ton
of MSS is $24.* Even with the $10/dry ton MSS credit, the MSW
facility is losing $3.50 per ton of RDF in fuel sales foregone.
Of course, this analysis does not take into account revenues from
the sale of the composted product.
*USDA, Costs of sludge composting, p. 13.
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TABLE 7
ECONOMICS OF LANDFILL CODISPOSAL
la) MSW with dewatered sludge (20% solids) added:
Ratio of Design
TPD Capacties
(MSW:MSS)
Cost Source
MSW
MSS
Other Costs
TOTAL
100:10
Capital
Cost (103)
$ 385
1,900
NA
$2,285
Cost/Ton*
$ 8
147
NA
$21*
Total
Annual
Cost (103)+
$ 245
450
NA
$ 695
1000:100
Capital
Cost (103)
$ 2,400
11,500
NA
$13,900
Cost/Ton*
$ 5
101
NA
$14*
Total
Annual
Cost (103)1"
$ 1,530
3,091
NA
$4,621
Ib) MSW with thickened sludge (5% solids) added:
Ratio of Design
TPD Capacities
(MSW:MSS)
Cost Source
MSW
MSS
Other Costs
400:10
Capital
Cost (103)
$1,185
1,250
NA
Cost/Ton*
$ 6
114
NA
Total
Annual
Cost (103)f
$ 734
349
NA
TOTAL
$2,435
$9*
$1,083
* Includes capital amortized over 20 years at 7%.
+ Based on 306 days per year (6 days/week minus holidays).
* Represents total cost per ton of combined waste (MSW + MSS).
0-.
r-o
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TABLE 8
ECONOMICS OF CODISPOSAL IN A REFRACTORY WALL SOLID WASTE INCINERATOR
Ratio of Design
TPD Capacities
(MSW:MSS)*
Cost Source
MSW
MSS
Other Costs §
100:10
Capital
Cost (103)
$1,500
1,850
750
Cost /Ton +
S 15
107
23
Total
Annual
Cost (103H
$459
327
70
TOTAL
$4,100
$ 25
$857
1000:100
Capital
Cost (103)
$ 6,500
8,000
6,000
Cost/Tori*"
$10
55
18
Total
Annual
Cost (103)t
$3,060
1,683
551
$20,500
$5,294
* MSS input is assumed 20% solids.
t Includes capital amortized over 20 years at 7%.
* Based on 306 operating days oer year 96 days/week minus holidays.
§ Other costs include a rotary drum type direct dryer and all equipment necessary for sludge handling.
U Represents total cost per ton of combined wastes (MSS + MSW).
ON
U)
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TABLE 9
ECONOMICS OF CODISPOSAL THROUGH COMPOSTING
3a) MSW processed Into RDF and composted (static pile) with
dewatered (20% solids) MSS
Ratio of Design
'iPD Capacities
(MSW: MSS)
Cost Source
MSW
MSS
Other Costs
250:50
Capital
Cost (103)
$ 6,750
4,500
NA
Cost /Ton*
$19
84*
NA
Total
Annual
Cost (10 )f
$1,423
1,285
NA
TOTAL
$11,250
$309
$2,708
3b) MSW processed into RDF and composted
(mechanical digester) with thickened
(5% solids) MSS
1000:50
Capital
Cost (103)
$17,000
3,150
NA
Cost/Ton*
$14
42t
NA
Total
Annual _ ,
Cost (10 )
$4,162
642
NA
$20,150
$15 =
$4,804
* Includes capital amortized over 20 years at 7%.
t Based on 306 days per year (6 days/week minus holidays).
T Does not include any revenues from sale of compost product.
§ Represents total cost per ton of combined waste (MSW + MSS).
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65
For this codisposal option to operate economically, the
following conditions appear necessary: no source, or a very expen-
sive source of bulking agent; a strong, lucrative market for compost;
no market for RDF as fuel. However, the cost per dry ton of MSS for
a bulking agent could be significantly reduced if a partially or
coarsely separated RDF from a simple pulverizer were used.
Part "b" of Table 9 reflects costs of the mechanical di-
gester process employed at a 20:1 MSW to MSS ratio with 5 percent
solids sludge. The process appears very economical since MSS pro-
cessing involves no more than thickening and transport to the com-
post site. However, until more data is provided through a full-
scale facility, serious questions remain concerning the practicality
of such a system.
2.4.4 Codisposal in an MHF/FBF. The economics for this approach
are shown in Table 10; the costs for both systems are comparable.
Again, it should be noted that the costs shown are for retrofitting
existing units, so that in reality some capital costs of the inciner-
ator may already have been incurred. The capacity ratios shown
(2.5:1) are within the range of optimum furnace performance, but
are much less than the equivalent population (13:1) proportions.
RDF is being used as fuel in the MSS furnace, thereby
eliminating the need for $22/day for sludge in fossil fuel cost.
Some $62.50 worth of RDF is required for each dry ton of MSS. How-
ever, with the fuel savings noted above, this codisposal system has
a lower annual cost than a combination of comparably sized single
purpose RDF and MHF/FBF systems.
It is reasonalbe to assume that the MSW facility would
receive a credit from the WWTP that approaches the value of the
MSS systems savings. If this credit equals or exceeds the RDF's
value as a fuel in alternative markets, then the system might be
attractive from both points of view. The economics of MHF/FBF
codisposal therefore hinge on whether $15/dry ton of sludge ($6/tcn
RDF x 2.5) is saved by the WWTP by entering the system. However,
other factors must be considered such as the wear and tear on the
equipment, increased dust loadings and ash removal resulting from
the incineration of RDF as opposed to a conventional fossil fuel.
A further consideration is the mismatch between the
large MSS population usage required compared to the relatively
small number of people needed to produce the proper input propor-
tion of MSW. As RDF facilities are capital intensive, the tendency
is to make them handle as much waste as possible to capture econ-
omies of scale. It may be possible to arrange to sell excess RDF
to outside users, or alternatively, RDF facilities could consider
other MHF/FBF operations as markets for thier excess RDF. In
-------
TABLE 10
ECONOMICS OF CODISPOSAL IN AN EXISTING MULTIPLE HEARTH OR FLUIDIZED BED FURNACE
a) MSW processed into RDF and added to an MHF with dewatered
(20% solids) MSS
Ratio of Design
TPD Capacities
(MSW:MSS)
Cost Source
MSW
MSS
Other Costs
250:100
Capital
Cost (103)
$ 6,750
18,500
5,000
Cost/Ton*
$ 19
1194
15
Tota]
Annual ,
Cost (.!•>)
$1,423
3,641
459
TOTAL
$30,250
$ 52
$5,523
b) MSW processed into RDF and added to an
FBF with dewatered (20% solids) MSS
250:100
Capital
$ 6,750
16,350
5,000
Cost /Ton*
$ 19
not
15
Total
Annual
Cost (103)f
$1,423
3,366
459
$28,100
3 49"
$5,248
* Includes capital amortized over 20 years at 7%.
t Based on 306 days per year (6 days/week minus holidays).
T $22 dry ton MSS has been deducted from the single purpose operating cost to account for eliminating the need for fossil fuel
(usually oil).
§ Includes cost of retrofitting furnaces to burn RDF.
t Represents total cost per ton of combined waste (MSW + MSS).
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67
any case, the sizing must be resolved if this approach to codis-
posal is to be economically attractive.
2.4.5 Mass Burning Waterwall Co incineration. The large (10:1)
and small (25:1) scale operations presented in Table 11 both re-
present technically efficient mixing ratios for this approach.
That is, the energy balance contains enough Btus to dry 20 percent
solids MSS and still export energy in the form of steam. The MSW
and MSS costs shown are from the single purpose process except for
the addition of sludge transportation costs and the "other costs."
For the 250:10 ratio, this latter category includes $18 per dry
ton MSS from the indirect dryer and related sludge handling costs
and also $44 per dry ton MSS as the cost of the steam required for
drying the sludge. This is based on 14,800 Ibs. of steam required
per dry ton MSS in an indirect dryer at $3/1,000 Ibs. steam. This
cost is based on the assumption that the waterwall facility charges
the WWTP the same price it commands on the open market for the rest
of its steam. These conditions are similar to the situation in
Harrisburg, Pennsylvania. Note that these conditions may not hold
true where the direct drying method is employed.
2.4.6 Dedicated Boiler. The conomics of this approach are
shown in Table 12. Except for the differences in MSW processing
costs, this system's economics are essentially the same as for
waterwall codisposal.
2.4.7 Modular Combustion Unit. The costs for this approach
shown in Table 13. The analysis is similar to the preceding water-
wall and dedicated boiler systems. Only the scale, MSW costs, and
the steam revenues vary from the previous discussions.
2.4.8 Copyrolysis. Table 14 displays the costs for two sizes
of copyrclysis facilities, with MSW to MSS ratios ranging from
2:5:1 to 10:2. The MSW costs shown include revenues from fuel pro-
ducts sale, but not tipping fees. MSS costs are based on single
purpose digesting and dewatering plus transportation to the site.
Other costs are derived from Weston's indirect drier costs and from
the costs of purchasing fuel from the pyrolysis system for drying
the sludge. The $22/dry ton MSS is based on EPA estimates of the
average Btu value of the pyrolysis fuel products and on Gordian's
estimate of the Btu requirements (14.8M/ton) for drying. As this
system is as yet unproven, the potential for error is high.
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TABLE 11
ECONOMICS OF CODISPOSAL IN A WATERWALL FURNACE
Ratio of Design
TPD Capacities
(KSW:MSS)*
Cost Source
MSW
MSS
Other Costs '
250:10
Capital ,,
Cost (10 )
$12,200
1,850
600
-L
Cost/Ton'
§
$13
107
62**
Total
Annual _ ,
Cost (10 )T
$ 995
327
190
TOTAL
$14,650
$19'
$1,512
1000:100
Capital ,
Cost (10 )
$37,000
8,000
4,500
Cost/Ton
§
$ 7
55
58**
Total
Annual ,
Cost (10 )*
$2,142
1,683
1,775
$49,500
17
$5,600
* MSS input is assumed 20% solids.
t Includes capital amortized over 20 years at 7%.
^ Based on 306 days per year (6 days/week minus holidays).
§ Includes revenues of $18/lnput ton MSW from sale of steam.
fl Includes costs of porcupine type indirect dryer and all related sludge handling costs.
** Includes costs of purchasing steam at $3/1000 Ibs. for sludge drying.
^ Represents total cost per ton of combined waste (MSW + MSS).
-------
TABLE 12
ECONOMICS OF CODISPOSAL IN A DEDICATED BOILER SYSTEM
Ratio of Design
TPD Capacities
(MSW:MSS)*
Cost Source
MSW
MSS
Other Costs
250:10
Capital ,
Cost (10 )
$13,000
1,850
600
Cost/Ton
$19§
107
62**
Total
Annual ., .
Cost (10J)t
$1,454
327
190
TOTAL
$15,450
$25
tt
$1,971
1000:100
Capital .,
Cost (10 )
$32,000
8,000
4,500
Cost /Ton
$95
55
58**
Total
Annual -, ,
Cost (10 )T
$2,754
1,683
1,775
$44,500
$18
tt
$6,212
* MSS input is assumed 20% solids.
t Includes capital amortized over 20 years at 7%.
t Based on 306 days per year (6 days/week minus holidays).
§ Includes revenues of $18/input ton MSW from sale of steam.
11 Includes costs of porcupine type indirect dryer and all related sludge handling costs.
** Includes cost of purchasing steam at $3/1000 Ibs. for sludge drying.
^ Represents total cost per ton of combined waste (MSW + MSS).
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TABLE 13
ECONOMICS OF CODISPOSAL IN A MODULAR COMBUSTION UNIT (WITH ENERGY RECOVERY)
Ratio of Design
TPD Capacities
(MSW:MSS)*
Cost Source
MSW
MSS
Other Costs
50:10
Capital
Cost (10 )
$1,250
1,850
600
Cost/Ton"*"
$85
107
51**
Total
Annual ., ,
Cost (10 )T
$122
327
156
TOTAL
$3,700
$33T
$605
100:10
Capital -
Cost (10 )
$2,000
1,850
600
Cost/Ton
$5§
107
51**
total
Annua 1 _. ,
Cost (10 )T
$153
327
156
$4,450
$19"*
$636
* MSS input is assumed 20% solids.
t Includes capital amortized over 20 years at 7%.
+ Based on 306 days per year (6 days/week minus holidays).
§ Includes revenues of $9/input ton MSW from sale of steam.
11 Includes costs or porcupine type indirect dryer and all related sludge handling costs.
** Includes cost of purchasing steam at $2.25/1000 Ibs. for sludge drying.
^-f Represents total cost per ton of combined waste (MSW -t- MSS).
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TABLE 14
ECONOMICS OF CODISPOSAL IN AN MSW PYROLYSIS UNIT
Ratio
TP0 Capacities
(MSW: MSS)*
Cost Source
MSW
MSS
Other Costs ^
250:1000
Capital
Cost (103)
$12,500
8,000
4,500
Cost /Ton"1"
$21§
56
36**
Total
Annual
Cost (103)f
$1,607
1,714
1.102
TOTAL
$25,000
$41**
1000:100
Capital
Cost (103)
$33,600
8,000
4,500
Cost/Ton"'"
$13§
56
36**
Total
Annual
Cost (103)*
$3,978
1,714
1,102
$4,423
$45,100
$20**
$6,794
* MSS input is assumed 20% solids.
t Includes capital amortized over 20% years at 7%.
£ Based on 306 days per year (6 days/week minus holidays).
§ Includes $9/incotning ton MSW from sale of fuel product.
11 Includes costs of porcupine type indirect dryer and all related sludge handling costs.
** Includes cost of purchasing energy for sludge drying from pryolysls process at $22/dry ton MSS.
tt Represents total cost per ton of comhlned waste (MSW 4- MSS).
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72
2.4.9 Summary and Conclusions. A summary of the economics
for the major codisposal options is presented in Table 15. This
table was prepared so that the costs of codisposal could be easily
compared with the cost summaries developed earlier for single pur-
pose systems. It should be noted that these systems are not directly
comparable with each other due to variance in scale.
A major conclusion of this economics section is that
codisposal can be seen to be competitive with most combinations
of single purpose systems. Landfill codisposal is cheaper than
all higher technology codisposal systems that involve landfilling
as one process. However, as noted earlier, for most communities
faced with MSW and MSS problems, landfilling is not one of the
options open. Consequently, high technology codisposal is an
economically sound alternative for urban areas with waste disposal
problems.
For codisposal to be economically attractive, its imple-
mentation must involve a saving to either the MSW or MSS adminis-
tration (providing the two are separate entities). This saving
is the key to cost allocation between the two agencies. The amount
of the saving and the agency to which it accrues dictate boundaries
and bargaining positions for negotiations between institutions.
As is frequently the case in Europe, one agency may be charged
with both MSW and MSS disposal thereby elminating the need for
bargaining. The leeway and the opportunity costs of alternative
approaches are among the significant economic determinants. The
remaining factor is the availability of Federal capital funding
under the Construction Grants program of PL 95-217. That aspect
is considered in the following chapter.
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73
TABLE 15
SUMMARY OF COSTS FOR CODISPOSAL OPTIONS
Total Annual Total
Capital Costs Net Costs of
($103) ($103)f
Codisposal Option* Small Large Small Large Small
Landfill
Small - 100: lot 20% Solids
Large - 1000:100 MSS
Large - 400:10 5% Solids
MSS
Incineration
Small - 200: 10+
Large - 1000:100
Composting
Small - 250: 50* 20% Solids
MSS
Large - 1000:50 5% Solids
MSS
MHF ( 250: 100) t
FBF (250: lOOt
Waterwall
Small - 250: lot
Large - 1000:100
Dedicated
Small - 250: lot
Large - 1000:100
Modular Incinerator!
Small - SOaof
Large - 100:10
Pyrolysist
Small - 250:10$
Large - 1000:100
2,285 13,900 695 4,621 21
§ 2,435 § 1>083 §
4,100 857 25
20,500 5,294
11,250 § 2,708 § 30
20,250 § 4,804 § 15
30,250 § 5,523 § 52
28,100 § 5,248 § 49
14,650 1,512 19
43,500 5,600
15,450 1,971 25
44,500 6,212
3,700 650 33
4,450 636
25,000 4,423 41
45,100 6,794
Cost Per Dry Ton
Combined Waste
(MSS + MSW)
Large
14
9
16
§
§
6
§
17
18
19
20
* All processes are assumed to use MSW plus 20% solids MSS except as noted.
t Costs do not include tipping fees.
t All ratios refer to facility capacity In tons per day as received MSW to dry weight MSS.
S For these systems, only one capacity range is applicable due to technological or economic
limitations.
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3. INSTITUTIONAL FACTORS AFFECTING CODISPOSAL
The technological and economic factors that bear on the potential
viability of codisposal have been examined in previous sections. This
chapter explores a third distinct family of equally important con-
siderations that have been labelled, for lack of a more precise term,
institutional factors. The term "institutional" refers to the com-
plex legal, organizational and administrative factors that deter-
mine the framework within which wastewater and solid waste manage-
ment operate. Specific aspects of each of these institutional
factors are discussed in this chapter. The purposes of the dis-
cussions are to:
1. Identify legal, organizational and administrative features
of wastewater and solid waste management that appear to be
impediments to codisposal.
2. Suggest how these obstacles might be avoided in planning
or implementing codisposal projects.
Two points should be borne in mind. First, institutional con-
siderations differ from project to project because of disparities
in local and state laws or because of differences in the nature of
wastewater and solid waste agencies from one municipality to another.
Second, the importance of institutional factors depends on whether
a project can be seen as technically or economically feasible. It
will eventually be necessary for those involved in codisposal pro-
jects to look at each codisposal project on its own merits; since
this study is not focused on specific projects, the concepts are
generalized.
In broad terms, the apparent institutional problem areas in
codisposal fall into two main groups, as follows:
® Inherent organizational differences between water and solid
waste management programs, specifically with respect to
planning and financing of codisposal facilities. These
differences are an outgrowth of the trends in program
devleopment in these two areas in the U.S. They encom-
pass not only differences in purpose and function, but
also related differences in organizational structure
and administration at all levels of government. The
discussion that follows points out that, as a practical
matter, these divergencies constitute obstacles pri-
marily to integrated project planning, not to operating
a project once it is conceived, planned, funded and
constructed. If basic differences can be satisfactorily
overcome in the planning stages of a project, they will
not obstruct operations.
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75
• Legal issues, such as waste control and coordination of
the complex mix of public and private interests in solid
waste handling and disposal. These issues are seen as
obstacles because they are key elements in the foundation
for proper project planning. Further, they are issues
that must be specifically addressed at several levels of
government. However, these legal issues are generally
no more of an obstacle than if single purpose resource
recovery or wastewater treatment projects are being
addressed.
3.1 Organizational Issues
As separate public works programs in the U.S., solid waste
management and water quality management have not developed in
parallel, so that today the two programs display fundamental
differences at all levels. A list of some key differences appears
in Table 16, which shows that disparities are manifest in the
mission, structure, function, authorities, financing, capitali-
zation, staff and operating modes. These disparities stem from
the different evolutionary processes which have formed the two
distinct programs as they now exist.
Water quality management programs were initiated as a local
public health concern; the emphasis on protection and eventual im-
provement of the nation's waterways is a relatively recent develop-
ment of federal policy. Stream quality is now the primary thrust
of most water quality management programs. Particular concern over
potential problems of sludge disposal is only now emerging as a
result of continual growth of nationwide treatment capacity.
Municipal wastewater treatment has also evolved as a wholly
public function. Widespread secondary and advanced treatment
requires capital-intensive facilities. To construct these facilities,
a sizeable federal grant program* was established to assist in finan-
cing. Grants under the Federal Water Pollution Control Act are made
available to public agencies, and corollary requirements of the pro-
gram have created a complex system of state, areawide, and local
water quality agencies. The effect of these program requirements
has been the creation of municipal or regional public bodies, vested
with considerable responsibility and authority to carry out the
planning and financing required to establish and run a wastewater
treatment facility.
*Federal Water Pollution Control Act, as amended - Construction Grants
program, P.L. 95-217 (40 CFR 35).
-------
TABLE 16
SOME KEY DIFFERENCES BETWEEN WASTE WATER AND SOLID WASTE MANAGEMENT
76
Waste Water Management*
Solid Waste Management
Focus is mainly on disposal of a li-
quid waste in a receiving waterway.
High capital requirements for
wastewater treatment.
Large, well-developed Federal grant
program underway with complex state,
areawide and local planning require-
ments.
Municipal facilities are almost
entirely owned by public sector.
Broad planning functions usually
carried out by an areawide waste-
water management agency.
In many cases, a separate organi-
zation exists to plan, finance and
own individual facilities.
Service organized according to
hydrologic boundaries.
Focus is mainly on land disposal
of a solid waste product.
Typically capitalized at a lower
level.
Limited financial assistance,
varied planning requirements,
emerging government regulation.
More than 50% of activity is by
private operators.
Planning is historically less
sophisticated, more fragmented;
broad planning done at the state
level, local planning ususlly
handled perfunctorily by indivi-
dual municipalities or counties
according to "least-cost" cri-
terion.
In many cases, these functions
are vested in an integral muni-
cipal or county agency with more
limited functions and possibly
other responsibilities.
Typically organized according to
local political boundaries.
Under the Clean Water Act of 1977, P.L. 95-217.
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77
The organizational development of solid waste management, on
the other hand, has progressed along different lines. While being
a public health concern, solid waste management has traditionally
been handled by the individual waste generator — the household,
factory, institution, etc. Further, where the focus of wastewater
treatment is on effluent and stream quality, the focus of solid
waste management has been mainly on removal of the waste to a
dumD or landfill.
Following the increase in population levels and densities,
much of the collection, hauling, and disposal functions of
larger cities and towns had to be performed in some centralized
manner. This has led to the growth of private waste hauling and
disposal industries in the United States. Unlike wastewater treat-
ment, the different components of solid waste management (i.e.,
collection, transport, processing, storage, disposal) can con-
ceivably be handled by different concerns, and in most places
in the U.S. have never been handled by one authority. At this
time, well over half of America's cities have their residential
waste collected by private carters.*
A federal grant program similar to that established for waste-
water treatment has never been established to help finance local
solid waste management, due in part to the far lower levels of
capitalization required and also due to the potential for inter-
ference with private operations. Consequently, solid waste manage-
ment has developed far less centralized activity than wastewater
programs. The various planning and financing functions are instead
vested in a melange of different groups, some public and some pri-
vate.
3.1.1 Planning Constraints. The evolution of two separate
programs for wastewater and solid waste management has influenced
the creation of distinct, separate program structures. Within each
structure, planning activities are guided by different requirements
and objectives.
In terms of economics, both programs are aimed at cost
minimization. However, since federal grants are available for a
significant proportion of capital costs, sewage treatment planning
emphasizes the minimization of locally supported operating costs,
*E.S. Savas, 1977. Of a large sample of cities surveyed, 66 percent
are served at least partially by private haulers, while 57.8 percent
are served exclusively by private firms.
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often substituting capital items in favor of added operating
expense. Virtually all solid waste project costs must be borne
locally, so that the emphasis has typically been on the lowest
cost mix of capital and other factors of production, often re-
sulting in labor- or land-intensive processes. Where high capital
solid waste processes have been recently installed, the basis of
economic planning has been revenues from resources or energy re-
covery rather than the availability of capital grant funding.
This is a significant barrier, in that codisposal largely means
capital intensity. While high levels of capitalization are typi-
cal of sewage treatment, they are less so in solid waste manage-
ment. Naturally, this introduces difficulties into financing
facilities. However, it also makes planning difficult, in that
the planning process for high capital solid waste facilities is
considerably more complex that that required for more typical
operations, such as landfilling. This additional complexity
creates an immediate demand for greater human, technical and data
resources, as well as for greater funding levels.
Similarly, the nature of facilities planning differs
between th two programs. In the interest of cost-effectiveness,
the Construction Grants Program has sponsored considerable re-
finement and standardization in process design for wastewater
treatment. In addition, the 201* planning process specifies that
the grant applicant demonstrate a cost-effective selection of
processes. The "cost-effective" analysis looks at a number of
factors, including unit costs, reliability, ease of operation and
environmental impact. Codisposal, as a relatively new application
of technology, is at a disadvantage in this procedure, since the
technology has not been demonstrated to the extent that it is
seen as a "standard" process option among 201 applicants or their
engineer-planners.
As mentioned previously, the geography of solid waste
and wastewater management concerns do not naturally coincide. Not
only are wastewater functions planned according to hydrologic
boundaries as opposed to municipal ones, but treatment plants are
also typically sited downstream from population centers, near the
planned outfall location. Sites available to meet these water-
related criteria may not be well located for solid waste handling.
It can also be seen from the discussion of codisposal processes
that the viable scales of operation do not lend themselves in all
cases for servicing the same geographic area or population base.
To some extent (e.g., joint siting and the need to organize sewage
collection for maximum gravity flow), these are practical problems
^Section 201, P.L. 95-217, ibid.
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that can be worked out during planning once a commitment is
made to consider codisposal. However, they also represent
real institutional issues in that the designation of joint
service area boundaries requires an overview level of planning
that is not usually found in the individual plans of two separate
organizations. Area-wide water quality management planning under
Section 208 operates at this overview level, but does not include
any solid waste planning mandate.
This issue is apparent in at least two current examples
of codisposal planning.* In Duluth, Minnesota, the refuse collec-
tion area includes customers who are not connected to the sewer
system; a problem arises in settling how to charge these cus-
tomers for the increased costs of codisposal. In Minneapolis,
the planning for codisposal that was undertaken by the Waste Con-
trol Commission found that competing resource recovery projects
in other parts of the Twin Cities threatened to absorb the refuse
available for codisposal. In consideration of these competing
demands (as well as a number of system-specific technical and
cost issues), the project was abandoned.
Another major organizational barrier to planning lies
in the difference between a completely public wastewater program
and a partly public, partly private solid waste activity. Apart
from legal issues, this interferes with planning in that private
operations have no incentive to plan or operate jointly. Further,
public agency planning that has an impact on local private en-
trepreneurs must be carried out with attention to securing their
support and preserving their livelihood.
The planning requirements for wastewater treatment
facilities also differ significantly from those for solid waste
facilities. The 201 Construction Grants Program proceeds through
a three step planning process, from initial study through design
to construction. The allocation of grant funds in each step is
governed by a priority list established in each state. The criteria
for assigning priorities are closely specified, and are based gen-
erally on the severity of the pollution problem and the size of
the affected population. Thus, Construction Grant applications
that include codisposal must compete against other water quality
problems to reach a position on the priority list where funds are
available. The emphasis in priority assignments is on first meeting
unfilled treatment needs.
Solid waste planning is not bound so closely to an out-
side schedule, since federal funds are not involved as often, nor
are available planning funds distributed in the same manner. Solid
*See Chapter 4 for a more detailed discussion of these two projects.
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waste planning schedules will be governed by the problems of
developing project feasibility and financing. Where resource
recovery is involved, the time required to develop firm markets
would be an equally significant factor.
Meshing the two schedules would involve careful coor-
dination at local, state and federal levels of planning. Of these
three levels, the local planning agencies are the most important,
for two reasons. First, the motivation for considering codisposal
should originate locally. Second, in the absence of strong solid
waste funding programs at both state and federal levels, there
may not be sufficient program coordination to ensure that schedules
can be brought together.
In summary, a comparison of wastewater and solid waste
management planning is characterized by different economic objec-
tives, different facility design and process selection criteria,
different geographical coverage and process scales, and different
degrees of public-private involvement. In several of these areas,
the differences point to joint planning on a regional or areawide
level as the appropriate approach to problem resolution.
3.1.2 Financing. Capital financing for wastewater treatment
is a combination of federal, state and local public funds, plus
private capital contributions for specific elements of the system
(through the Industrial Cost Recovery program). For the treatment
works and major interceptor sewers, eligible capital items may be
75 percent funded by a federal grant under the Clean Water Act.*
The remaining 25 percent is provided by state and local sources
in shares that vary from state to state. The state share may be
provided as a grant or as a low-interest loan, while the local
share is in most cases raised by general obligation or revenue
bonding. For collection facilities other than major interceptors,
funds are also provided locally from bonded indebtedness or from
assessments against individual property owners.
Operating costs are not subsidized by grant funds; they
must be generated locally by user charges. These charges must be
sufficient to cover all current costs of operation, maintenance
and repair, as well as to provide funds to retire local bonds and
any other capital debt, such as low-interest loans.
Solid waste management activities are funded in a
different manner. The most important difference is that limited
*Several exceptions to this funding percentage are possible,
notably the availability of 85 percent funding for certain
innovative or energy saving treatment processes.
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federal funds are available only for project planning, not for
capital financing. In addition, there is a greater presence of
private risk capital in application to both collection and dis-
posal activities. Thus, the potential capital funding mix includes
local public funds, perhaps augmented with state-level funding
assistance, and private funds from entrepreneurs operating solid
waste handling concerns.
A second basic difference is in the origin of solid
waste operating and debt retirement funds. Collection, hauling,
and, to a degree disposal are covered by user charges. However,
for costly solid waste disposal operations, project funding re-
lies on revenues potentially available from the sale of recovered
resources or energy and from the disposal fee. The expectation
of these revenues is often the basis of planning for high tech-
nology solid waste facilities, where materials on energy revenues
are planned to offset increases in the total cost of disposal;
without these revenues, the facility would not be feasible. The
key to assuming sufficient income from the sale of recovered energy
or materials lies in successful market development. In effect, in
a project involving energy recovery, codisposal is likely to be
subordinate to the need to serve the energy market. For example,
if providing the maximum volume of available steam is a central
issue in negotiations between the energy producer and the steam
purchaser, then codisposal may be deemed impractical, as it may
be a net user of recovered energy under some conditions.
Perhaps the most important issues in codisposal financing
revolve around the problems of cost allocation both for capital and
operating costs. Each of these cost categore is made up of three
components, if codisposal is viewed as the union of two otherwise
separate activities. One component consists of the costs attribu-
table solely to solid waste handling activities; the counterpart to
these are the costs attributable solely to sludge handling. The
third element of cost comprises the joint costs, which refer to
those parts of the process that handle both sludge and solid waste.
The two direct cost components are relatively easy to account for,
but there is no clear-cut way to allocate the joint costs. Never-
the less, if two separate agencies exist, or if the project serves
two different populations, the cost must be allocated between the
two so that capital financing proportions and user charges can be
developed. Capital cost allocation is particularly important in
establishing the part of project funds that can be provided by an
EPA Construction Grant.
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At this writing, EPA is in the process of establishing
a new policy for capital cost allocation. Under the former policy,
joint costs were allocated between solid waste and wastewater
treatment according to a concept and formula* developed for allo-
cating the costs of multiple purpose water resource projects. The
concept was based on the presumption that the cost of a multiple
purpose project would be less than the total cost of two single
purpose projects. The formula procedure was essentially a standard-
ized method for allocating joint project costs in proportion to
the savings realized in each purpose of the multiple purpose pro-
ject. In codisposal, joint costs were those incurred for the
simultaneous incineration of MSS and MSW, or those incurred to
produce RDF for sludge burning. It is not yet clear what form
EPA's new policy will take, but the Agency's Wastewater and Solid
waste offices are both hopeful that an incentive for codisposal
will be provided.
The other aspect of codisposal project financing is
the allocation of operating costs. This allocation must be made
so as to split the cost of joint processing between the solid
waste and the sludge agencies. Another factor in allocation may
be the division of charges between those customers served by both
processes and those served by only one. This allocation is not
likely to be a significant difficulty, since onpratinp costs can
be divided according to the division of capital costs for funding
purposes.
Whether EPA's eventual funding policy is a disincentive
to codisposal appears to depend upon the type of project under con-
sideration and the nature of the agencies sponsoring the project.
For codisposal processes that are primarily for solid waste dis-
posal such as large scale energy recovery, the funding policy is a
trivial barrier, if any at all, for two reasons. First, the solid
waste facility should be feasible in its own right. Since sludge
disposal is usually a large energy user, it is basically just a
part of the facility's energy market. If the Contruction Grants
funding policy will assist the sewer agency in financing the equip-
ment to deliver and prepare the sludge for incineration, the capital
funding is not an issue to the agency financing the energy recovery
facility.
However, codisposal may not appeal to the solid waste
agency if the cost of solid waste handling increases as a result,
*U.S. EPA, Construction grants program requirements No. PKM 77-4.
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or if codisposal involves only a part of the solid waste stream.
Under these circumstances the cost allocation policy is a key
issue, since the total cost of solid waste handling is entirely
dependent on the extent to which EPA funding will assist in the
cost of processing.
It should be noted that the pending cost allocation
procedure is distinct from EPA's funding policy for financing
"alternative and innovative" treatment processes. Under this policy.*
several advantages may be available in considering alternative or
innovative processes such as codisposal. The first is that EPA
may allow for the present worth cost of such processes to be as
much as 15 percent higher than the most cost-effective traditional
process and the alternative process can still be eligible for a
federal grant. Further, the grant may be as much as 85 percent
charged against special funding allocations in each state. To
account for the added risk, EPA will pay up to 100 percent of the
cost of process replacement if failure should occur within two
years of project start-up.
EPA is studying the possibility of revising the cost
allocation procedure in order to cover multi-purpose projects
(such as codisposal or wastewater reuse) on the same terms as
other, single purpose innovative processes. One option is to es-
tablish the limit of grant eligibility according to the cost of the
cheapest single-purpose alternative. The 15 percent premium could
also be added to this cost. The effect of this policy change
would be to increase the grant eligible funds in codisposal, there-
by reducing the solid waste shares of project capital outlays. The
new policy is expected to be issued in early 1980.
3.2 Legal Issues
Control of the sold waste stream is a critical element in
planning codisposal projects. Sewage sludge is controlled by
the municipal or regional authority as part of its responsibility
for the environmentally proper handling of sewage. However, the
more fragmented, partially public and partially private handling
of solid wastes results in a less clear picture of solid waste
control for the public sector. Since a prerequisite of any solid
waste resource recovery system is the assurance of a steady waste
supply, municipal solid waste must be controlled in some fashion
by the concerned public agency.
*43CFR 44022, Sep. 27, 1978.
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In some municipalities, the collection and disposal of solid
waste is a public function, and in such cases, effective public
control of the waste stream already exists. However, almost
twice as many cities in the U.S. have their residential refuse
collected not by public employees but by private collection firms.*
In these cases, waste control can be achieved in one of two
fashions: by offering a tipping fee at the public facility which
is lower than competing landfills or other area disposal alterna-
tives; or by legislating, at the local or state level, public
control of the municipal waste stream.
Currently, the least controversal means of achieving public
control of the waste stream is by offering a lower tipping fee
at the disposal facility. This is a less dependable form of
waste control than actual ordinances or state laws, as reflected
in the fact that mortgage bankers will often encourage munici-
palities to seek some form of legal waste control prior to reven-
ue bond financing for solid waste processing facilities, with the
argument that such arrangements significantly reduce the long term
risk involved in such projects. Public control of the solid waste
stream can be legislated in one of two fashions: by instituting
flow control of the waste or by actually stipulating public owner-
ship of the waste.
Flow control is currently the more prevalent of the two methods;
it requires that the solid waste set out by residents for collection
be delivered to the municipality's facility(ies) by the private
refuse haulers, although the solid waste is not the property of
the municipality. Such an arrangement has thus far been legis-
lated by the State of Florida; the City of Akron, Ohio; Monroe
County, New York; Jefferson County (Louisville), Kentucky; and
the Western lake Superior Sanitary District in Duluth, Minnesota.
The second method, which at present has been legislated in the
U.S. only by the State of Wisconsin, is actual ownership of the
waste stream by the municipality. Figure 12 gives an example of
a statewide waste ownership law as proposed in the General Assembly
of the State of Indiana. Waste control legislation in effect ensures
the municipality's access to a steady supply of municipal solid
waste for the life of its processing facility. However, munici-
palities and states are likely to encounter varying degrees of
resistance from the private waste hauling and disposal industries
when trying to enact such enabling legislation.
*E.S. Savas, Policy analysis for local government: public vs.
private refuse collection.
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Under either type of waste control legislation, private waste
haulers and landill operators can be subjected to an increased
degree of public control. The industry's feeling, if it can be
generalized, is that such levels of control diminish or eliminate
any profit incentive to the local operators by limiting their
disposal options and therby disallowing the negotiation of lower
tipping fees at area landfills. In addition, both types of flow
control laws may also effectively remove any private recyclers and
scrap dealers from the loop by requiring direct delivery to the
municipal facility. In the extreme case of municipal waste own-
ership, the haulers are reduced to providing a strict public ser-
vice, and are subject to regulation as public utilities under the
law.
The waste control issue is currently being challenged in Federal
District Court in the case of Glenwillow Landfill, Inc. et al. v.
City of Akron et al.* The City of Akron, Ohio, which enacted
flow control legislation in order to facilitate the establishment
of an areawide solid waste resource recovery facility, is being
challenged by Glenwillow Landfill, Inc., a private landfill oper-
ator, as to the constitutionality of the law. The legal issues
involved which define this case as a Federal Constitutional concern
are described below:
• Interstate Commerce of Recyclables - recycling materials
from municipal solid waste is considered a form of inter-
state commerce, as is some hauling and disposal of solid
waste by private operators. Such activities are thus
regulated by a large body of federal statutes which
cannot be preempted by local or state legislation. The
plaintiff in this case argues that Akron's flow control
law amounts to an unconstitutional infringement on in-
terstate commerce activity.
• Anti-trust Violation - the plaintiff argues that the City
is violating the Clayton Act by establishing a monopoly
over a given area of commercial activity.**
Glenwillow Landfill, Inc. et al. v. The City of Akron is now
in the late discovery state, and is expected to move to trial in
the near future. It is unclear at present whether the City will
be successful in defending the constitutionality of its law.
*Case C 78-65A of the Northern District, Eastern Division, of the
Federal Court of Ohio.
**A significant body of legal precedents exists which defines the
hauling, processing and disposal of municipal solid waste as a form
of commerce.
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DIGEST
Adds 1C 19-2-1.5 to establish the ownership in solid waste in local units
of government or in regional solid waste districts.
A BILL FOR AN ACT to amend 1C 19-2 is amended by adding a new chapter concern-
ing the ownership of solid waste.
BE IT ENACTED BY THE GENERAL ASSEMBLY OF THE STATE OF INDIANA:
SECTION 1. 1C 19-2 is amended by adding a NEW chapter 1.5 to read as
follows:
Chapter 1.5. Solid Waste Ownership.
Sec. 1. (a) Each regional solid waste management district, or city, town,
or county, if it is not within a regional solid waste district, has a franchise
right to solid waste within its jurisdiction which it may exercise itself or
contract away.
(b) Each regional solid waste management district, or city, town, or
county, if it is not within a regional solid waste district, shall issue, by
ordinance, specific regulations stating the methods and placement for materials
for pick-up, or if pick-up is not to be made, specific regulations designating
how solid waste material is to be deposited at those sites. Materials placed
in the manner and places specified in the regulations are presumed to be
abandoned, and the owner's rights to those materials are relinquished to the
regional solid waste district, or city, town, or county, as appropriate.
(c) A copy of each such ordinance shall be published two (2) times in a
newspaper within that jurisdiction before the ordinance takes effect.
Figure 12. Example of waste control legislation - Waste Ownership
Act. Source: Draft prepared by the Indiana Solid Waste Management Com-
mission, August 30, 1978.
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A recent decision of the U.S. Supreme Court, however, may have
significant implications on the anti-trust issue for the above case
and future waste control legislation. The Supreme Court's decision,
handed down in the Spring of 1978 in the case of Lafayette y.
Louisiana Power and Light Company, states that municipalities do not
have the same exemption from the Clayton Act's anti-trust provisions
that states are allowed By the terms of the Act. This sets legal
precedent to the effect that cities cannot create monopolies. Such
a precedent indicates that any future waste control legislation
might have to be enacted on a statewsie basis; even this is contin-
gent upon a ruling in the Akron case that waste control legislation
in general is not offensive on interstate commerce grounds. State-
wide laws, of course, are considered by the private waste management
industry to be fully as threatening, if not more so, than local
statutes, for all the same reasons enumerated here. These can be
expected to meet with varying degrees- of resistance and legal
challenge in the future.
To add to the dilemna of waste control facing many municipalities,
some private carters or landfill operators will hold long-term con-
tracts for handling of a municipality's waste, preventing enactment.
of waste control legislation until the contracts can be renegotiated
or allowed to expire.
3.3 Conclusions
The most significant institutional issues affecting codisposal
relate to project planning and financing, and to the basic legal
formulations of solid waste management. The perspectives and oppor-
tunities for resolution of these three problem areas are different,
as explained below.
3.3.1 Legal and Market Structure Issues. The legal issues of
waste control and coordination with private market operations are
pervasive and fundamental, overshadowing the prospects of codisposal
in general (as well as other high technology solid waste disposal
techniques), without regard to specific projects. The resolution
of these issues is likely to depend on evolving policy decisions
and legal precedents, rather than on ad hoc arrangements at the pro-
ject level.
It is beyond the scope of this analysis to address the ques-
tion of whether broader public involvement is desirable in the areas
of solid waste collection, hauling and disposal. Nevertheless, it
is an important question. Codisposal means high capital cost and
complex technology in solid waste handling; these two characteristics
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indicate increase public regulation and ownership. Given the re-
latively informal and minimally capitalized nature of private
municipal refuse disposal in most areas, a trend toward greater
public control or ownership will bring considerable pressure to
bear on traditional market structures and arrangements.
The presence of private enterprise raises certain ob-
stacles to codisposal, but at the same time, private capital and
private entrepreneurs are essential to the financing and imple-
mentation of resource recovery (and hence codisposal). Thus, care
is important in establishing the limits of public authority over
solid waste handling. A number of approaches are available for
preserving the options of private initiative. These include the
following:
• Use of market incentives to control waste flow
• Use of full-service arrangements for facility
implementations
• Use of public funds to reduce the risk inherent in
the application of new technologies
3.3.2 Planning Constraints. The majority of codisposal
planning obstacles originate in the basic differences between
solid waste and wastewater management. It appears that a number
of these obstacles can be dealt with by approaching codisposal
planning functions at a regional level. This would have several
advantages. First, it would allow solid waste and water quality
managment concerns and hierarchies to be integrated at the level
of the 208 agency or the A-95 planning agency, where other regional
issues (population growth, land use, transportation, environmental
protection, etc.) are under more or less continuous review.
Second, it would create an overview sufficiently broad to identify
possibilities for solid waste management and codisposal at the
most economical scales. Third, if a project were proposed that
involved multiple jurisdictions, the regional agency would be a
form for discussion of regional arrangements for funding or im-
plementation.
The development of an overview level planning procedure
would assist in coordinating dialogue among planners at the project
level and above. However, another important aspect of planning is
data to support dialogue and decisions. In this regard, codisposal
is at a disadvantage. It will be necessary to develop a steady
flow of technical and economic information about the technologies of
the projects planned or underway, and the evolution of federal and
state wastewater and solid waste management policies.
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3.3.3 Financing Alternatives. Since the codisposal of muni-
cipal sludge and solid waste may involve wastewater treatment works
and Construction Grants funds, the central issue is the policy for
cost sharing under the Clean Water Act. As discussed previously,
a new EPA cost allocation policy is imminent and it is hoped that
any new policies would be designed to allow the 115 percent pre-
mium and 85 percent funding for codisposal as an "alternative/
innovative" technology. In this regard, the funding policy would
not appear to constitute a definite barrier to codisposal projects.
However, it is useful to examine project financing from other
viewpoints to see whether other policy arrangements within the
limits of the Construction Grants program are relatively more con-
ducive to codisposal.
Considerations of Economic Theory. For the most part,
economic theory offers very little useful guidance for the alloca-
tion of costs in multiple purpose projects. This is particularly
true of codisposal. The reasons for this are primarily the following:
• The most widely used economic criterion, that of
"economic efficiency," is of no practical value in
guiding allocation. To achieve economic efficiency,
it is necessary to equate the marginal social cost
of waste disposal with marginal benefits in order
to find the optimum level and type of solid waste
and sludge disposal. While some measures of mar-
ginal cost could be estimated, it is now easy to
estimate the marginal social benefits of waste
management. Besides the fact that many benefits
cannot be quantified or evaluated, the benefits
of the two programs do not accrue to the same
groups of people. Essentially all that the effi-
ciency criterion dictates is that codisposal should
be cheaper than the cost of single purpose dis-
posal; if no cost savings are possible, do not
codispose.
• Without information regarding benefits, there is
no useful method in economic theory that will
pinpoint the "proper" relative shares of joint project
costs. Thus, allocation of the costs that relate to
joint processes (and also the savings from codisposal)
is a matter to be decided by negotiation or by a policy
rule. EPA's former cost allocation policy, termed
the "Alternative Justifiable Expenditure" procedure
(AJE) is such a policy rule, as are the revised allo-,
cation procedures now under consideration.
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Other Criteria for Policy Evaluations. In the absence
of a theoretical basis for cost allocation, the next best guide
is to assess alternative cost allocation procedures against several
simple rules. With respect to these, a cost allocation policy
should:
• Help to achieve EPA's stated goals. The most
definite goal statement is found in the policy
that encourages alternative and innovative
processes, including codisposal and energy
efficient processes. The constraining policy
is that EPA is not empowered to spend Clean
Water Act funds for solid waste disposal pur-
poses. However, as the policy is now struc-
tured, it does allow funding for a portion of
a codisposal project.
• Encourage least-cost wastewater treatment and re-
siduals handling. The cost-effective analysis
required in 201 planning should ensure this,
along with the natural incentive for local
agencies to minimize their costs.
• Encourage least-cost solid waste disposal processes.
While EPA is restricted from funding solid waste
disposal under the Clean Water Act, its policies
should not tend to increase the cost of this
essential service. This implies that cost allo-
cation should promote the most economical scale
for processing of both wastes. It also implies
that all sources of project revenues and finan-
cing should be taken into account.
• Be equitable and consistent in application.
These are useful characteristics for any public
funding program. They require that the funding
policy be clearly stated and be based on the
same data from project to project. It could be
difficult to achieve consistency in codisposal
funding, since the viable processes differ con-
siderably in technology, scope and cost. Using
these criteria, and looking at codisposal in
terms of the mechanics of financing, it is
possible to construct an alternative approach
to EPA1 funding posture.
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An Alternative Cost Allocation Procedure. In codisposal,
costs are incurred to deliver and prepare wastes for processing,
to process the combined waste flow, to market recovered resources,
and to dispose of residuals. Revenues are available from solid
waste and wastewater user charges and from the sale of recovered
resources. Financing is a matter of matching revenue sources with
cash needs for operation, maintenance and debt service.
Each participant in the codisposal project has some
limited financial capacity to contribute to capital and operating
costs. Asa practical matter, for each participant, this limit is
equal to the cost of the next cheapest available alternative.
Within these limits, and considering project revenues, many financ-
ing schemes can be worked out.
Table 17 summarizes the limits to financial participa-
tion in the 1000 TPD waterwall incinerator discussed previously.
It can be seen in Table 18 that when the financing available within
these limits is applied to the hypothetical project, a potential
surplus exists among all sources. This surplus is an artifact of
the cost of alternative sludge disposal in a multiple hearth fur-
nace, but it should be borne in mind that codisposal is favored be-
cause of its advantageous total cost. Therefore, other available
options should generally be more expensive.
This single example is by no means conclusive. Its
purpose is simply to demonstrate the effect of approaching EPA
funding as though the agency were a financing partner in the ven-
ture. With this approach, even the restricted 75 percent funding
available as EPA's contribution to the MHF alternative is sufficient
to approach what appears to be adequate financing. However, there
are a number of implicit features of this approach, both pro and
con, as follows:
Pro Con
Recognizes the importance of • May not be implementable
project revenues. under PL 95-217.
Based on alternative costs. • Should be based on a full
20-year cash flow analysis.
Maximum flexibility.
• Would require a separate
detailed analysis of each
case.
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TABLE 17
SUMMARY OF AVAILABLE FINANCIAL SUPPORT FOR CODISPOSAL - 1000 TPD
WATERWALL INCINERATOR, 100 TPD SLUDGE
92
Project
Participants
Limits of Financial Support
Nature
Amount
Solid Waste
Agency
• Maximum tipping fee
• Revenues from sale of
energy and recovered
materials
$ 7-12/ton
$18/ton for steam
$ 3 ton for materials
Local Waste-
water Agency
• O&M cost of next most
cost-effective sludge
disposal option (as-
sume MHF)
• Local share of capital
cost (25%)
$2,540,000/yr.
$4,875,000
EPA
Either
a) 75% of capital cost
of MHF, or
b) 85% of 115% of MHF
capital cost
$14,625,000
$19,061,000
Local Energy
User
• Unit price of alternative $2.50-3.50/1000 Ibs. of
energy source steam
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93
TABLE 18
ANALYSIS OF FUNDING SOURCES - 1000 TPD WATERWALL INCINERATOR,
100 TPD SLUDGE
General Elements of Cost
Capital Cost
Present Worth O&M Cost
Total
$ 43,500,000
74,179,000 (20 years @ 7%)
$117,679,000
Available Funds*
Steam Revenues
(1000 TPD @ $18/ton)
Tipping Fee
(1000 TPD @ $7/ton)
O&M Cost, MHF
Capital Cost, MHF
Local Share @ 25%
EPA Share @ 75%
Total
Surplus/(Deficit)
$ 58,352,000
22,692,000
22,908,000
4,875,000
14,625,000
$127,452,000
$ 9,773,000
Potential Uses of Surplus
• Reduce EPA share to $4,852,000.
• Reduce Local share to zero and MSS O&M cost by $15/ton.
• Reduce tipping fee to $4/ton.
• Reduce steam price to $2.50/1000 Ibs. from $3.
* Steam revenues, tipping fee, and O&M cost are shown as the
present worth over 20 years at a 7% discount rate.
-------
The limitations of the Clean Water Act may well be the
deciding limitation. But in any event, such an analytic approach,
as shown simplistically in Table 18, or in a more detailed cash
flow format, would be a useful planning tool.
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95
4. IMPLENTING CODISPOSAL
4.1 A Few Real World Situations
4.1.1 Ansonia, Connecticut. In 1976 Ansonia constructed a
solid waste incineration facility. The following year, in a sep-
arate decision, the City installed a spray drier using the flue
gases from the furnaces to dry sludge from the wastewater treat-
ment plant. Ansonia's Department of Public Works runs both the
wastewater treatment plant and the collection of solid waste.
The service area for both of these functions is delineated by
the City's boundaries.
While the refuse incinerator was out of service due to
an explosion in the shredder, Ansonia took the opportunity to
rebuild the air pollution control equipment to meet air pollution
standards and to modify the sludge drier. Meanwhile, solid waste
was being transported a landfill at a cost of $14 per ton and the
sludge was dried in drying beds before being landfilled. The wet
scrubber has been replaced and the incinerator is now back on
line. However, as no funds were available for repairs and modi-
fication needed for the drier, sludge is still landfilled following
solar drying.
The solid waste incineration consists of two rocking
grate, continuously stoked incinerators with a combined capacity
of 200 TPD of MSW. The plant operates on an eight hours per day,
five days per week schedule, burning 40 TPD of shredded MSW, which
represents about 70 percent of Ansonia's solid waste load. The
remainder is primarily bulky refuse which is landfilled.* A com-
bined flow diagram of the wastewater treatment and solid waste
disposal operations is shown in Figure 13.
The sewage treatment plant generates 12.5 dry TPD
of digested sludge with a 5 percent solids content. When the
codisposal system was operating, the sludge was pumped there to
be dried in a Nichols spray drier to 85 percent solids. As the
drier never reached design capacity, only about half of the sludge
was ever dried in it, with the remainder being dried in drying
beds. The spray drier will be modified in order to increase its
capacity; after modification, the dried sludge will be given away
for use as a soil conditioner.
*Roy F. Weston, Inc., op. cit.
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Raw Sewaga
Primary
Degritter
I Settling Tank I-
Aeration Tank
Secondary
I J Settling Tank
Chlorinator
Sludge Storage
Feed Pump
To Drying Beds
To Naugatuck
River
To Landfill
Figure 13. Codisposal process schematic, Ansonia, Connecticut. Source: Roy F. Weston, Inc.
-------
97
The implementation of the codisposal project at Ansonia
was facilitated by having the authority for the disposal of both
MSW and MSS lie with the Department of Public Works. As the ser-
vice areas for these functions are the same, covering only the
City of Ansonia, it was not necessary to allocate the operating
costs of the project between the wastewater and solid waste users.
The economics of landfilling MSW in northeastern communities such
as Ansonia are such that incineration is frequently a viable method
of disposing of MSW. Sludge drying provides a convenient market
for the recovered energy from MSW incineration, and is usually a
cost-effective method of sludge disposal.
4.1.2 Central Contra Costa County, California. Planning for
the expansion of the Central Contra Costa Sanitary District (CCCSD)
sewage treatment plant began in 1970; it was subsequently decided
to reclaim the effluent for industrial reuse. A water contract
was negotiated with the Central Contra Costa Water District (CCCWD)
which will market the water to a nearby oil refinery.
Two things combined to make CCCSD consider codisposal:
o The high lime treatment will result in a relatively
inert sludge (30 percent volatile) which would
require a large amount of fuel for incineration.
CCCSD also plans to recalcinate to recover lime,
which is also an intensive operation.
o Natural gas service has been withdrawn, and alter-
native fuels are prohibitively expensive.
The CCCSD is responsible for wastewater collection and
treatment and the disposal of sewage sludge. The service area
boundaries for solid waste and sewage collection are shown in
Figure 14. The collection of wastewater will be gradually ex-
tended to the boundaries of the District when the expansion of
the treatment plant is complete.
The authority for the collection and disposal of solid
waste was given to CCCSD so that the District could franchise the
collection of MSW by private haulers in unincorporated areas of
Central Contra Costa County. Collection rates are set by the
Cities of Concord, Martinez„ Pleasant Hill and Walnut Creek, and
by CCCSD in Lafayette and unincorporated areas.
Solid waste from Central Central Costa County is
collected by private haulers and taken to the Acme Fill Corpor-
ation's sanitary landfill near Martinez. The tipping fee for
-------
er Service
yUithori zed
: Water Service
CONTRA COSTA COUNTY BOUNDARY
PRESENT SOLID WASTE SERVICE AREA BOUNDARY
CCCSO BOUNDARY
PRESENT AREA SERVED BY CCCSD
A ACME FILL CORP. LANDFILL
O CCCSO TREATMENT PLANT
10 MILES
Figure 14. CCCSD boundary and present service area, and solid waste area service boundary for
Acme corporation landfill. Source: Brown and Caldwell, 1974.
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99
MSW at this facility is $0.75 per cubic yard,* which is approx-
imately $2.60 per ton, assuming a density of 290 Ibs. per cubic
yard. The useful life of this facility is at least 20 years, and
possibly 40 years, depending on the amount of waste imported from
other parts of Contra Costa County.
The present CCCSD treatment plart has a capacity of
30 MGD which is being increased to 40 MGD. Two sludges will be
produced from the centrifugal classification stage in the completed
CCCSD plant. One will contain mostly organic solids and will have
a 12 to 18 percent solids content, with a heat content of 4300 Btus
per pound of dry solids. The second sludge will contain mostly
lime solids (66 percent of total solids), and will have a heat
content of 1300 Btus per pound of dry solids, at 24 to 30 percent
solids. The generation rate of the first sludge is expected to
be 35 dry TPD, and 60.5 dry TPD for the second sludge.
In 1976 Brown and Caldwell and the BSP Division of
Envirotech Corporation retrofitted a six-hearth multiple hearth
furnace (MHF) at the old CCCSD treatment plant to use refuse-
derived fuel. Tests run on that unit indicated that pyrolysis
(starved air combustion) of an RDF and sludge mixture at a ratio
fo 2:1 was technically and economically feasible.
The two existing eleven-hearth MHFs at the CCCSD treat-
ment plant will be retrofitted so that RDF can be fed to hearths
number 4 and 5. The top hearth in each furnace will be adapted
for use as an afterburner. Two additional ten-hearth MHFs will
be constructed with RDF feed ports on hearths number 3 and 5.
Two waste heat boilers will be constructed in order to provide
steam for the generation of 100 percent of the electricity re-
quirements of the plant. A schematic depiction of this codisnosal
process is shown in Figure 15.
The design capacity of the proposed solid waste pro-
cessing facility is 1200 TPD, which is the anticipated MSW gen-
eration in 1986. Processing will include primary shredding and
air classification after which the light fraction will undergo
cyclone separation, screening, and secondary shredding to produce
about 605 TPD of RDF. Plans to recover ferrous metals and alum-
inum have been abandoned.
The construction of the new MHFs and the modifications
of the old units to accept RDF will make the plant 100 percent
eligible for funding under EPA's Clean Water Act Construction
*Brown and Caldwell, Central Contra Costa Sanitary District:
solid waste resource recoverv study.
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31 TPO
SOL 10 fUEL
FROM RESOURCE
RECOVERY PLANT
2B* TPO
150 " STEAM (125,000 K/HR)
VENT
ME flTING/COOLING
AER * T ION AIR
ELECTRICITY
VENT
VENT
° T/ie t*islir
-------
101
Grants Program (75 percent federal, 12% percent state, and 12?i
percent local funding). The capital cost associated with gen-
erating electricity will be partially eligible (approximately
20 to 30 percent) for Construction Grant Funds. These costs in-
clude the waste heat boilers, the solid waste processing facility,
and the generators.
CCCSD does not intend to charge a tipping fee for MSW
deposited at the resource recovery facility, but it will be able
to dispose of its ash and the heavy fraction produced in RDF pro-
duction at the Acme Fill Corporation site without charge or for
a nominal fee only.* The Acme Fill Company is owned by a group
of private solid waste collection companies who would be reluctant
to lose the revenues from solid waste converted to RDF that would
normally be landfilled at their facility. Although CCCSD has the
authority to require that MSW be taken to the solid waste pro-
cessing facility, it chose not to exercise this authority because
of political considerations.
The driving force behind the implementation of the CCCSD
codisposal project appears to have been the extremely high costs
projected for sludge incineration and recalcinating using fossil
fuels. The additional costs associated with codisposal will be
paid for by the wastewater user, since CCCSD has declined to re-
quire that MSW be deposited at the RDF facility for an artificial
tipping fee. Presumably, these costs will be offset by the reduced
cost of fuel.
4.1.3 Duluth. The Western Lake Superior Sanitary District
(WLSSD) was formed in 1971 by enabling legislation passed by the
Legislature of the State of Minnesota. Its purpose is to improve
and protect the water quality of the St. Louis River and St. Louis
Bay, as well as to safeguard other important rural natural re-
sources that lie within the District's boundaries. The first goal
of WLSSD was the construction of a regional advanced wastewater
plant to replace seven obsolete primary treatment facilities. This
plant is under construction in Duluth.
The original design of the WLSSD regional facility called
for the incineration of sludge in multiple hearth furnaces. How-
ever, after the Oil Embargo of 1973-1974 and the subsequent sharp
rise of fuel oil prices, WLSSD examined other fuels to meet its
sludge disposal needs. It was found that the codisposal of sludge
*John Larson, CCCSD, personal communication.
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102
with MSW would be more cost-effective than the original system.
A comparison of the costs for the latter and the best codisposal
scheme is shown in Table 19.* When it became clear that MSW
could provide the energy for thermal sludge disposal, enabling
legislation was passed to specify WLSSD's solid waste powers
and responsibilities. WLSSD encompasses portions of two
counties, Carlton and St. Louis (see Figure 16), both of which
are covered under existing county-wide or regional solid waste
management plans. The problem of overlapping responsibilities
has been avoided by close cooperation between WLSSD and responsi-
ble county departments. The WLSSD anticipates that both Carlton
and St. Louis Counties will recognize WLSSD's solid waste plan by
formal amendment of their respective county plans to incorporate
WLSSD's plans by reference.**
Municipal solid waste is hauled by private companies
to two landfills, the Duluth Disposal Company Sanitary Landfill
(DDCSL) and the Carlton County Sanitary Landfill (CCSL). These
landfills are located within the WLSSD boundaries, but also serve
portions of St. Louis and Carlton Counties outside the boundaries
of WLSSD. In 1975 the MSW generation rate in WLSSD was 248 TPD;
this figure is expected to increase to 315 TPD by 1984.*** Land-
fill costs at DDCSL and CCSL are currently about $2.49 to $2.57
per ton of MSW.****
The regional advanced wastewater treatment plant re-
cently constructed by WLSSD in Duluth is expected to generate
approximately 68.4 dry TPD of waste activated sludge (WAS) de-
watered to 20 percent solids. Also included in this figure are
grit and screenings. It is anticipated that the heating value
of this sludge will range between 5060 and 5400 Btus per pound
of dry solids.
The codisposal technology selected for this project
provides for the combustion of a combined RDF/MSS feed in a
fluidized-bed furnace (FBF). The RDF will be prepared by coarse
shredding, magnetic separation, air classification. The light
fraction will be shredded to a maximum size of 1 to 1^ inches
*Consoer, Townsend & Associates, Solid waste disposal system:
preliminary engineering reoort.
**WLSSD, Solid waste management plan. 1977 version.
***Consoer, Townsend & Associates, op. cit.
****WLSSD, op. cit.
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103
TABLE 19
COMPARISON OF COSTS FOR ORIGINAL SYSTEM AND SYSTEM WITH
COINCINERATION IN FLUIDIZED-BED FURNACE*
Original
System
Coincineration
with FBF
Capital Investment
Engineering, Legal Fees,
etc., at 10%
TOTAL
Amortization at
15 Years
Personnel
Electrical Power
Process Fuel
HVAC Fuel
Maintenance
Residue Disposal
Waste Transfer Operation
Gross Annual Cost
($000)
11,165
1,117
12,282
1,307
226
108
1,022
261
343
30
3,297
15,848
1,585
17,433
1,855
432
285
NIL
NIL
457
119
126
3,274
Credits
Disposal Fees at 45
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104
DISPOSAL FACILITIES
] LANDFILL SERVICE AREAS
WLSSD
Figure 16. WLSSD boundaries and service areas for Duluth Disposal
Company Sanitary Landfill (DDCSL) and Carlton County Sanitary Landfill.
Source: Western Lake Superior Sanitary District.
-------
105
for use as RDF. A waste heat boiler is used to recover heat
from the flue gases; the steam thus generated can be either used
within the plant or sold. A potential market for steam is the
nearby transit authority building. A schematic of the system is
shown in Figure 17. Construction of the codisposal system is
complete and is currently undergoing shakedown.
The capacity of the solid waste processing facility
(SWPF) is 280 TPD for each of two process trains, although only
160 TPD will be required for the incineration of the sludge.
WLSSD hopes eventually to operate the SWPF at near capacity
if a market for the additional RDF can be found. Meanwhile, the
excess MSW will be landfilled at the CCSL.
The 1974 enabling legislation prohibits WLSSD from
using revenues from the operation of disposal facilities (i.e.,
tipping fees) to fund the operation of the wastewater treatment
facilities. The intent of this legislation was to prevent the
residents of Carlton and St. Louis Counties who will not be served
by the WLSSD wastewater treatment plant from being assessed for
part of the facilities' costs through increased tipping fees at
WLSSD disposal facilities. Consequently, the solid waste tipping
fee will include the capital, operating and maintenance costs for
only the scale, tipping floor, primary shredder, and ferrous
metals separation at the SWPF. The solid waste user also receives
the credits from the sale of recovered ferrous metals. The re-
maining costs associated with the SWPF are to be allocated to the
wastewater user. The tipping fee has tentatively been set at
$3.10 per ton.*
The Federal Government is funding 75 percent of the
capital costs for both the regional advanced wastewater treatment
plant and the SWPF under EPA's Construction Grants Program. State
funds are providing a further 15 percent, with the remaining 10
percent to be financed locally through the sale of General Obli-
gation bonds. EPA's allowance of 75 percent funding eligibility
for the entire capital costs (including the SWPF) occurred prior
to the issuance of any formal Federal policy concerning codis-
posal projects. In the future, funding will be provided according to
a specific multi-purpose allocation formula.
The ability of WLSSD to gain control of the municipal
solid waste stream through the 1974 enabling legislation played
a major role in the successful implementation of the project.
It prevented a situation where WLSSD would have to compete with
a privately run landfill (DDCSL) for MSW, and has allowed WLSSD
to levy a tipping fee of $3.10 per ton at the SWPF which is $0.50
to $0.60 per ton greater than prevailing landfill costs. The
*Minutes of WLSSD Board Meeting, October 25, 1977.
-------
106
MUNICIPAL
REFUSE
REFUSE
RECEIVING
OPERATION
PRIMARY
SHREDDER
MAKE UP WATER
PUMP
, .MAGNETIC
r- SEPARATOR
AIR
1LASSIF1ER
SURGE
TANK
conditioning
transfer
pump
STEAM CONDENSER
HEATING .VENTILATION
& AIR CONDITIONING
W&NETIC
SEPARATOR
dewatered
sewage
W4S7E
HEAT
BOILER
FLUID/ZED
BED
REACTOR
V
ferrous
metals
to
scrap
metal
industry
combustion
air
blower
QUENCHER
noncombustables
& ash residue
to landfill
ash
orocessor
final effluent
sewage
reatment
plant
VENTURI
SCRUBBER
ti.
Figure 17. Process schematic for Western Lake Superior Sanitary
District Coincineration Facility.
-------
107
justification for the higher fee is that DDCSL does not comply
with environmental standards and the tipping fee would have to
have been increased to pay for the required modifications. A
second reason for success was the approval of full construction
Grants funding for the SWPF capital costs. These factors greatly
increased the economic attractiveness of the project to WLSSD.
A.1.4 Glen Cove, New York. The City of Glen Cove (population
27,000 is currently dumping its sewage sludge in the ocean and
hauling its MSW tojthe New Jersey Meadowlands for landfilling.
With the EPA ban on ocean dumping after 1981 and New Jersey's efforts
to prevent the disposal of out-of-state solid waste at their landfills,
the City was forced to examine alternative disposal options for both
sludge and MSW.*
The City examined three systems:
o co-burning of MSW and MSS and generation of electric power
for the wastewater treatment plant and incinerator complex,
o a sludge burning incinerator at the wastewater treatment
plant and an independent refuse disposal facility, and
o sludge disposal at a proposed Nassau County regional sludge
disposal facility and refuse disposal at the existing Hemp-
stead incineration facility.
The first of these alternatives was considered to be the most cost-effec-
tive and is being implemented by the City.
The City of Glen Cove controls both the collection of MSW and the
operation of the wastewater treatment plant through the Department of
Public Works. The City currently collects 125 TPD of MSW and pays a pri-
vate company $22 per ton to haul it to landfill sites in New Jersey. The
existing 4 MGD treatment plant generates 3.5 dry TPD of sludge at 20 per-
cent solids which is barged to the Atlantic Ocean for disposal. An 8 MGD
activated sludge nitrification treatment plant is under construction and
will produce 5 dry TPD of sludge also at 20 percent solids.
In the codisposal phase of the project, a thin layer
of sludge will be placed on the surface of the MSW being fed to
a conventional mass-burning incinerator. A waste heat boiler will
produce steam which will generate all of the treatment plant's
electricity by means of a 2.2 megawatt multi-stage condensing
turbine generator set.** A schematic rendering of the codisposal
process and a cross-section of the incinerator are shown in
Figure 18.
* William F. Cosulich,Co-burnine of sludge and refuse and waste heat recovery
** William F. Cosulich, op. cit.
-------
Sludge
a) Schematic of Codisposal
Process
Flototion
Thickeners-
Pumps
Aeroted Sludge
Storoge TonKs
108
Feed Pumps O
-------
109
The Glen Cove facility will consume 175 TPD of MSW plus
the 5 TPD of MSS produced by the treatment plant. Since only 125
TPD of MSW are generated within the Glen Cove city limits, 50 TPD
will have to be imported from nearby communities. Glen Cove will
have to compete for MSW with the energy recovery facility located
in the Town of Hempstead. Since Glen Cove is closer to the commun-
ities involved, city officials are confident that a tipping fee
of $12 per ton (vs. $16 to $18/ton at Hempstead) will be low enough
to attract adequate supplies of MSW.*
Construction Grant Funds will be available for
approximately 50 percent of the entire Glen Cove wastewater treat-
ment and solid waste incineration complex. The wastewater treat-
ment plant, up to the centrifuges, is 100 percent eligible for
Construction Grants Funds, and the furnaces are partially eligible.
The energy recovery aspects of the project (waste heat boilers, gen-
erators, etc.) are ineligible.
The idential service areas for sewage treatment and MSW
collection, the consolidation of these activities, and the ultimate
disposal of MSW and MSS under the authority of one city department
(Public Works) undoubtedly have greatly facilitated the implemen-
tation of codisposal in Glen Cove. The need to allocate operating
costs between the solid waste and wastewater users is minimized,
and the centralization of authority minimizes the problems of
coordinating actions regarding MSW and MSS disposal.
Another factor that favored the adoption of codisposal
in Glen Cove was the fact that it became necessary to find alter-
native disposal systems for both MSS and MSW at about the same
time when the City was planning to construct a new wastewater treat-
ment plant. Thus, Glen Cove was not irreversibly committed to a
disposal alternative for either MSS or MSW and could consider a
combined disposal option.
4.1.5. Harrisburg, Pennsylvania. The Harrisburg refuse
incinerator was completed in 1972, and it was subsequently de-
cided to use it for the disposal of sewage sludge as well.
Digested sludge has been combusted at the facility by adding it
directly to the furnace feed hopper. A sludge drying facility
using steam generated by the refuse incinerator is under con-
struction and is scheduled for completion by late 1979.
*Ernest Pascucci, Public Works Director, City of Glen Cove,
N.Y., personal communication.
-------
no
The authority for the collection and disposal of MSW
is exercised by the Department of Public Works for all solid
waste generated within the City limits of Harrisburg. The City
requires that all MSW be dumped at the incinerator. Private
refuse haulers bring MSW from suburban communities to the incin-
erator and are levied a tipping fee of $10.80, $11.80 or $12.80
per ton, depending on the bulk density of the waste. Many sub-
urban haulers find it more economical to use these facilities
than to haul their loads for greater distances to transfer
stations or landfills, where the tipping fees are $7.00 to $7.50
and $5.00 to $6.00, respectively.
The 31 MGD capacity wastewater treatment plant is oper-
ated bt the Department of Public Works in Harrisburg, but is owned
by the Harrisburg Sewage Authority which also is responsible for
financing the facility. The service area of the treatment plant
includes Harrisburg and six suburban communities. The cost of
treatment is shared on the basis of sewage flow contributed to
the system.
The wastewater treatment process produces primary
sludge and a waste activated sludge conditioned with aluminum
sulfate. The combined sludge will be pumped to the dewatering
facility where it will be dewatered to 22 percent solids by
vacuum filtration and then dried to 85 percent solids using steam.
This product may be marketed as a mulch/soil conditioner or burned
in the incinerator. It is anticipated that about two-thirds of
the energy used in drying the sludge can be recovered from the
combustion of the dried product. The Harrisburg Sewerage Authority
will buy steam from the incinerator for sludge drying and pay an
additional fee to dispose of the dried sludge at the incinerator.
The Harrisburg incinerator consists of two waterwall
furnaces with a design capacity of 720 TPD, although it normally
operates seven days per week and consumes 400 TPD of MSW. Metals
are separated from the MSW after hammermilling and shredding the
bulky materials, and also from the residue after combustion using
magnetic separators. It is hoped that the residue can be recovered
for use in road construction as road base aggregate and asphalt.
The dewatering facility and the equipment that will
deliver the dried sludge to the furnace feed hopper will be 100
percent eligible for funding under the Construction Grants Program.
The chances of success for a codisposal project are
greatly enhanced in a situation as Harrisburg's, where the via-
bility of refuse incineration has been demonstrated. Institutional
problems can be greatly reduced by selecting a technology that re-
quires no commonly-owned equipment. This allows the capital and
-------
Ill
operating costs incurred by the sludge and solid waste components
of the codisposal project to be clearly defined. This was achieved
in Harrisburg by having a separate sludge dewatering facility whose
only connections with the incinerator will be pipe for incoming
steam and a means of conveying the dried sludge to the feed hopper
at the incinerator. These will also be the points of economic trans-
fer between the wastewater treatment plant (Harrisburg Sewerage
Authority) and the incinerator (Harrisburg Department of Public
Works), as the former will pay for steam and the disposal of dried
sludge. The advantage of this arrangement is that it results in
a mutually beneficial economic relationship between the two in-
stitutional entities, rather than a partnership where some equitable
method must be found to allocate the costs and/or benefits to the
partners.
4.1.6 Minneapolis - St. Paul, Minnesota. The Metropolitan
Waste Control Commission (MWCC) is in the process of expanding
the Metropolitan Wastewater Treatment Plant (Metro Plant) from 219
MGD to 290 MGD. The sludge disposal system must be desinged to
handle the associated increase in sludge generation from 288 TPD
to 390 TPD. At the time of design the Metro Plan was experiencing
increasing interruption of its natural gas supply, which, when com-
bined with the rise in the price of oil, led to the careful con-
sideration of codisposal.
In 1975 the MWCC proposed the construction of sludge
disposal facilities for the copyrolysis of sludge and refuse.
An independent evaluation of this system found that it was not
the most cost-effective alternative and raised questions as to
whether a dependable supply of MSW could be secured.* MSWW subse-
quently abandoned the copyrolysis project in favor of a system that
will incinerate heat dried sludge in MHFs, recoverying energy using
waste heat boilers. Flue gases from the MHFs will be used to dry
the sludge in two rotary driers.**
The authority for the collection and treatment of waste-
water in the Twin Cities Metropolitan ARea (TCMA) is held by the
Metropolitan Council (MC). Representatives from the seven counties
in the TCMA sit on the MC. This body determines the boundaries of
the sewage service area and determines the long-term development of
*Camp Dresser & Me Kee, Inc., Evaluation of Proposed Sludge
Disposal Facilites with Pyrolysis of Sludge/Refuse - Metropolitan
Wastewater Treatment Plant.
**Sludge. (11): September 19, 1978.
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112
MWCC. The MWCC is composed of commissioners from the communities
in the MWCC service area, and is concerned with the operation of
its wastewater treatment facilities. MWCC operates two treatment
plants, the Metro Plant (219 MGD) in St. Paul and the Severa Plant
(24 MGD) in Burnsville, which receive sewage from Minneapolis and
St. Paul and their suburbs within about a 20 mile radius. MWCC
currently incinerates 288 TPD of sludge in MHFs at the Metro Plant
using fuel oil only when natural gas supplies are interrupted.
Natural gas service has been discontinued.
In creating the MWCC, the Minnesota Legislature intended
that this body should eventually acquire authority over the collec-
tion and disposal of MSW; however, this authority has not been trans-
ferred from the counties. Solid waste is collected by the City of
Minneapolis and by private haulers in St. Paul and suburban areas.
St. Paul and some suburban communities do not have mandatory refuse
collection.
Municipal solid waste is currently hauled to sanitary
landfills (there were ten operating within 30 miles of the Metro
Plant in 1975) (see Figure 19). Tipping fees ranged from $2.20
to $4.00 per ton at these facilities in 19J5.
The codisposal system under consideration called for
the copyrolysis of some of the sludge with solid waste to produce
a pyrogas to be used in the incineration of the remainder of the
sludge in MHFs. Heat was to be recovered from these furnaces by
a waste heat boiler producing steam to be used in the sludge driers.
The char produced in the pyrolyzer was also to be recovered and used
as a fuel. A schematic rendering of the proposed system is shown
in Figure 20.
The RDF was to be prepared by primary shredding, pri-
mary air classification, secondary shredding and secondary air
classification. Ferrous metals and aluminum were also to be re-
covered from the heavy fraction. The design capacity of the
processing plant was 360 TPD. A depiction of the proposed solid
waste processing system is shown in Figure 21.
Since MWCC does not have control over the municipal
waste stream, the allocation of costs between the system's solid
waste and wastewater users would have occurred through the tipping
fee. This fee would have had to be low enough to attract MSW on
a competitive basis. MWCC calculated that a tipping fee of $6 to
$8 at the Metro Plant would be more attractive option than hauling
MSW to outlying landfills for many communities In the center of the
TCMA.
-------
113
METRO PLANT
10
20
30 Miles
I i
• Sanitary Landfill
Figure 19. Map of Twin Cities Metropolitan Area (TCMA) showing
location of metro plant and landfill sites. Source: Camp, Dresser &
McKee, Inc.
-------
©_
,© ©
CHAR
/•—
2
PRIMARY SLUDGE
V
ROLL
PRESSES
SECONDARY SLUDGE
HEAT
COND.
REFUSE
WHD
i©
STEAM
INCINERATORS
ASH
©
FILTER PRESSES
MIXER
DRIED SLUDGE
PYROGAS
CHAR
(TO PRIMARY SUBSYSTEM)
Figure 20. Proposed MWCC codisposal system. Source: Camp, Dresser & McKee, Inc.
-------
FLOOR
STORAGE
PRIMARY
SHREDDING
PRIMARY
AIR DENSITY STORAGE
SEPARATOR QlNS (52O T)
SECONDARY
SHREDDING
SECONDARY
AIR DENSITY
SEPARATOR
EMERGENCY BY-PASS
NON-FERROUS
SEPARATORS(2)
STORAGE
BIN (6T)
*-TO SLUDGE/REFUSE
MIXER
RESIDUAL
FERROUS METALS
DIVERTER
NON-FERROUS
SEPARATOR 10
:x
J///J
ALUMINUM
TO LANDFILL
. T MIXED
NON-FERROUS
Figure 21. Proposed MWCC solid waste processing system. Source: Camp, Dresser & McKee, Inc.
-------
116
In their evaluation of the proposed project, Camp
Dresser & McKee, Inc. (CDM) expressed conern about the avail-
ability of solid waste.* Two waste-to-energy projects were
under consideration at the time, one in Hennepin County and the
second in St. Paul proposed by Phoenix, Inc., a trash hauling firm
which has a five-year contract with Minneapolis to haul MSW to
landfill sites. CDM concluded that when non-processable solid
waste (construction and demolition wastes, inert materials, trees,
fly ash and slag, auto hulks, etc.), the 25 percent reduction
in MSW generation that occurs in the winter and the waste gen-
erated beyond a 30-mile radius of the Metro Plant are substracted
from the total waste generation in the TCMA, there may not be
sufficient MSW to support the two-waste-to-energy projects, let
alone the Metro Plant codisposal scheme (see Table 20).
CDM also concluded that both the capital and annual
operating costs of the codisposal system would be significantly
greater for the proposed codisposal system than for a system
that directly incinerates sludge and recovers energy for sludge
drying.
4.2 Codisposal as an Alternative to Ocean Dumping
For seaboard communities on both the East and West coasts of
the U.S., the ocean dumping of sewage sludge and other waste pro-
ducts (demolition debris, refuse, dredge spoils, etc.) has been
an economically attractive and operationally simple disposal al-
ternative. It involves only the collection and barge transport
of liquid sludge to a designated point at sea, where the sludge
load is then discharged.
In recent years, attention has been focused on the hazards
that this procedure poses to marine life as well as the aesthetic
problmes that can be created as sludge migrates toward the shore-
line with ocean currents. Consequently, a federal ban on all
ocean dumping activities has been implented and will become effec-
tive in 1981.
For those cities which currently ocean dump their sludges, a
new sludge management program must be developed and implemented
before the 1981 deadline. Since these cites are in a unique posi-
tion of being able to design disposal systems from the ground up,
it is assumed that they have greater incentives and opportunites
to utilize innovative systems/technologies than any other U.S.
*Camp Dresser & McKee, Inc., op. cit.
-------
117
TABLE 20
AVAILABILITY OF PROCESSABLE MSW IN TWIN CITIES METROPOLITAN AREA (TCMA)
FOR THE PROPOSED CODISPOSAL FACILITY AT THE METRO PLANT*
Tons Per Week
Average MSW generation 72,500
Non-processable -33,500
MSW beyond 30 miles -1,500
25 percent winter reduction in MSW generation -9,000
Waste recycled -5,OOP
Availability of processable MSW 23,500
Waste required by Phoenix Inc. facility 12,000
Waste required by Hennepin Co. facility 13,000
25,000
* Source: Camp, Dresser & McKee, Inc.
-------
118
community. Therefore, the seven* major ocean dumping municipal-
ities were investigated to identify the status of their waste-
water management planning and to assess their interest in codis-
posal as a sludge management option. However, in most cases, the
institutional impediments to its implementation are sufficiently
great so as to preclude it as a viable option within the 1981
timeframe. Therefore, a number of these cities have either elim-
inated codisposal from consideration, or have elected to implement
an interim sludge disposal system, while planning to re-evaluate
codisposal along with alternatives at a later date. Table 21
summarizes the status of planning activities with the ocean
dumping communities (for specific details, See Appendix C).
The major concern of the ocean dumping communities at this
time is to ensure that a practical, reliable alternative sludge
disposal system can be implemented before the 1981 ban. While all
of the communities contacted have expressed a philosophical commit-
ment to innovative systems such as codisposal, they are unwilling
to risk the possibility that the resolution of institutional prob-
lems, particularly establishing the authority to control wastes
and a program of joint management, could delay codisposal's im-
plementation beyond the 1981 timeframe. This is particularly true
for those communities in which the current method of solid waste
disposal is landfilling. In these cases, a new solid waste manage-
ment system would have to be developed, as well as a sludge manage-
ment system, before more sophisticated codisposal options like
coincineration are possible. As a result, many of the ocean dumping
communities have reserved codisposal systems for consideration in
their "second stage" planning efforts, while settling on an "interim"
sludge disposal plan (usually composting) which can be implemented
within the designated timeframe, and which will allow them time for
more careful consideration of the other options.
Cost is also mentioned as an area of concern by these communi-
ties. While the cost of coincinerating solid waste with sewage
sludge may not significantly exceed that of sludge incineration,
the cost of processing the solid waste prior to incineration can be
considerable, especially for those communities which currently land-
fill their solid waste at little cost. In addition, several commun-
ities reported that uncertainties over federal and state funding
policies disposed them toward single purpose alternatives.
*The seven waste management agencies contacted are responsible for
about 92 percent of the total sludge quantity permitted for ocean
dumping on the East coast.
-------
TABLE 21
SUMMARY OF 201 PLANNING STATUS IN OCEAN DUMPING COMMUNITIES
Major Ocean
Dumping
Communities
Bergen Co.
Sewer
Authority
Linden
Roselle-
Rahway
Sewer
Authority
Middlesex
County
Sewer
Authority
Passaic
Valley
Sewer
Commission
Actual
Quantity
Dumped
(Wet Tons)
(1976)
246,000
228,000
300,000
579,000
Status of
201 Planning
Report
Not Yet
Completed
Not Yet
Completed
Completed
Not Yet
Completed
Recommended
Sludge
Management
Alternative
Interim: Compost-
ing Long Term: Co-
disposal
Composting
Incineration in
MHFs
Comments
Would like to implement the Union
Carbide Purox System as a long term
disposal alternative.
Has recently begun to consider coin-
cineration of sludge and solid waste
in modular combustion units, utiliz-
ing low-termperature pyrolysis.
Codisposal not recommended because
of:
- Institutional problems (obtaining
authority, allocating costs, etc.)
- Cost (solid waste currently land-
filled at $3/ton) .
Looking at several codisposal op-
tions, which would be preferred "if
economics work out." Worried about
Clean Air Act. Not enough land to
compost, so will be forced into some
other alternative.
-------
TABLE 21
SUMMARY OF 201 PLANNING STATUS IN OCEAN DUMPING COMMUNITIES
(Con't)
Actual
Quantity Recommended
Major Ocean Dumped Status of Sludge
Dumping (Wet Tons) 201 Planning Management
Communities (1976) Report Alternative Comments
Nassau 401,000 Complete Not Yet Finalized Conducting pilot studies on compost-
County ing, codisposal, landfilling. Co-
Department disposal (Black Clawson) preferred.
of Public Participation in the Hempstead or
Works Glen Gove projects also being con-
sidered.
Westchester 138,000 Interim Composting (Being Coincineration eliminated due to an-
County Report Re-evaluated) ticipated air quality problems. Pre-
Department Complete sent solid waste disposal plans are
of Environ- for resource recovery through steam
mental generation (project stalled).
Facilities
New York City 2,152,000 Not Yet Interim: Compost- Opportunities are being identified
Department Completed ing Long Term: for coincineration of sludge in
of Water Not Yet Decided existing and planned combustion
Resources units, such as refuse incinerators
and utility boilers. To date, the
extent of interest has not been de-
termined .
-------
121
Unlike most communities in the U.S., however, the ocean r'umpine
communities in general seem to be well suited for the implementation
of codisposal systems. The communities are predominantly large,
producing in excess of 200 dry tons of sludge per day. Thus, they
would be able to benefit from the economies of scale inherent in
capital intensive sludge processes, including codisposal. Further,
these cites are all located in a densely populated geographic area
along the Eastern seaboard, making the large scale land disposal of
sludge and solid waste difficult, if not impossible, for all of them
over the long run. Sludge incineration would appear to be a more
appropriate disposal alternative, which would likely make codisposal
increasingly competitive over time. Until codisposal's intitutional
problems are resolved, however, it is likely that the ocean dumping
communities will continue to pursue single-purpose sludge and solid
waste management programs.
-------
122
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128
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129
APPENDIX A. MUNICIPAL SOLID WASTE ECONOMIC DAT£*
All source references cited in the following tables may be found
at the end of this appendix.
-------
TABLE A-l
LANDFILLING*
MSW
Unloading
Optional
Shredding
Baling
Spreading
and
Compacting
Covering
System Economics based on Sources and Assumptions shown below:
Range
Capital/TPD
2,400-4,800
Range-Annual
Cost/Ton
1.50-20.00
Avg.-Annual
Cost/Ton
6.00
Range-Revenue/Ton
Materials Energy
NA
Avg.-Revenue/Ton
Materials Energy
NA
Avg. Net
Cost/Ton
6.00
Gordian Estimate for 3 facility sizes
Capital Annual Cost — $/Ton
TPD (x 1000) Capital O&M Total
100 385 1.76 6.24 8.00
400 1,185 1.32 4.68 6.00
1000 2.400 1.10 3.90 5.00
Revenue — $/Ton
Materials Energy
NA
NA
NA
Net Cost — $/Ton
8.00
6.00
5.00
• Assumptions:
Capital is determined as 22% of total annual cost; capital amortization is at 7% over 10 years.
*Source: 1, 2, 3.
-------
TABLE A-2
REFRACTORY WALL INCINERATION/MODULAR INCINERATOR
MSW
Refractory Wall
Combustion
Chambers
APC
.fc
^.To
Atmosphere
Residue to Landfill
Modular Incinerator
MSW_ Batch
Primary
Combustion
Chamber
^
w
Secondary
Gas
Combustion
Chamber
To
Atmosphere
T
Residue to Landfill
• System Economics based on Sources and Assumptions shown below:
Range
Capital/TPD
Refractory Wall
7,000-25,000
Range-Annual
Cost/Ton
8.00-15.00
Modular Incinerator
12,000-24,000 8.00-18.00
Avg.-Annual
Cost/Ton
12.50
12.00
Gordian Estimate for 3 facility sizes
- Refractory Wall
Capital Annual Cost — $.Ton
TPD
100
400
1000
(Thousands) Capital O&M Net $/Ton
1,500
3,200
6.500
4.60 10.40 15.00
2.50 9.50 12.00
2.00 8.00 10.00
Range-Revenue/Ton
Materials Energy
Avg.-Revenue/Ton
Materials Energy
NA NA
NA NA
Avg, Net
Cost/Ton
12.60
12.00
- Modular Incinerator
Capital Annual Cost — $/Ton
TPD (Thousands) Capital O&M Net $/Ton
10
50
100
225
750
1,250
7.00 9.00 16.00
4.50 7.50 12.00
3.85 5.15 9.00
• Assumptions:
Capital amortized over 20 years at 7%. Resource recovery is not considered as part of these systems.
* Source: 8, 20, 21.
-------
TABLE A-3
RESOURCE RECOVERY - WATERWALL INCINERATION*
MSW
*
Unloading
and
Storage
Stea
k
Combustion
Chamber
with
Boiler Tubes
tn^
. APC
To
Atmosphere
Residue to
System Economics based on Sources and Assumptions shown below:
Range
Capital/TPD
Range-Annual
Cost/Ton
20,000-51,500 13.00-38.00
Avg. Annual
Cost/Ton
25.00
Range-Revenue/Ton
Materials Energy
Avg.-Revenue/Ton
Materials Energy
NA
7.00-30.00
(steam)
NA
18.00
Avg. Net
Cost/Ton
7.00
Gordian Estimate for 3 facility sizes
Capital Annual Cost — $/Ton
TPD (x 1000) Capital O&M Total
250 12,000 15.00 16.00 31.00
400 17,000 13.25 15.75 29.00
1000 37,000 9.65 15.35 25.00
Revenue — $/Ton
Materials Energy
NA
NA
NA
18.00
18.00
18.00
Net Cost — $/Ton
13.00
11.00
7.00
Assumptions:
Both front and back end materials recovery is possible with this system. However, in this report
front end recovery is discussed in the dedicated boiler section and the marketing of back end re-
covered materials is assumed to be too speculative to consider it as a measurable revenue source.
. .Capital is amortized over 20 years at 7%. Average steam revenues are based on $3.00/1000 Ibs. of
steam and assuming no efficiency variation among differing boiler sizes.
Source: 1, 4, 8, 9, 10.
-------
TABLE A-4
RESOURCE RECOVERY - RDF (DUST)
MSW
-*
Ov
Unlo,
'ai
Stoi
ersiz
Shre
iding
-
-------
TABLE A-5
RESOURCE RECOVERY - RDF (WET)*
MSW
Unloading
and
Storage
w
W
Hydrapulper
Ferrous
Recovery
h*
k.
1
r
Liquid
Cyclone
i
r
Glass
Recovery
w.
Thickening
Process
± Residue
Ferrous Scrap to
Landfill
Gullet
V
RDF
System Economics based on Sources and Assumptions shown below:
Range
Capital/TPD
Range-Annual
Cost/Ton
16,000-20,000 18.00-25.00
Avg.-Annual
Cost/Ton
20.00
Range-Revenue/Ton
Materials Energy
Avg.-Revenue/Ton
Materials Energy
.90-5.80 3.00-10.50 3.40
5.00
Avg. Net
Cost/Ton
12.50
Gordian Estimate for 3 facility sizes
Capital Annual Cost — $/Ton
TPD (x 1000) Capital O&M Total
250 5,000 6.15 17.85 24.00
400 7,000 5.40 16.60 22.00
1000 16,000 4.90 15.10 20.00
Revenue — $/Ton
Materials Energy
3.40
3.40
3.40
5.00
5.00
5.00
Net Cost — $/Ton
15.60
13.60
11.60
Assumptions:
Materials assumptions are the same (as for previous dust RDF system) for all recovery processes.
RDF revenues are based on process efficiency of 70% for converting Btus/lb. incoming MSW to Btus/
f Ib. of RDF compared to $1.00/million Btu price for coal less 30% handling charge.
*Source: 1, 3, 11, 5.
-------
TABLE A-6
RESOURCE RECOVERY - RDF (FLUFF, DENSIFIED)*
Unloading
MSW • fc and
Storage
1
Bulky Ferrous
Recovery
^
werrous Scrap
Primary
Shredder
i \_
Residue
to
Landfill
Air
Classifie
Lights Secondary „„„
r Shredder
Heavies
Aluminum
Recovery
^
Aluminum
Glass
Recovery
* /
Gullet Fluff
RDF
"ZONAL1" — > Pellitizer
d-
RTVF
• System Economics based on Sources and Assumptions shown below:
Range Range-Annual
Capital/TPD
Cost/Ton
7,000-32,000 12.00-22.50
• Gordian Estimate for 3 facility
Avg. -Annual
Cost/Ton
17.00
sizes
Range-Revenue/Ton Avg. -Revenue/Ton Avg. Net
Materials Energy Materials Energy Cost/Ton
.90-5.80 0-10.50 3.40 4.50 9.00
Capital Annual Cost — $/Ton Revenue — $/Ton
TPD (x 1000) Capital O&M Total Materials Energy Net Cost — $/Ton
250 6,750 8.25 13.75 22.00 3.40 4.60
400 8,800 6.75 13.25 20.00 3.40 4.60
1000 17,000 5.25 11.75 17.00 3.40 4.60
• Assumptions:
14.00
12.00
9.00
Capital is amortized over years at 7%. Materials revenue is same as previous processes. RDF
revenue is calculated on basis of 70% process efficiency in Btu/lb. conversion from imout .
MSW to RDF, compared to $l/million Btu, price of coal less 30% handling charge.
*Source: 1, 2, 3, 4, 5, 6, 11, 15, 16.
IDens'ifying or pelletizing adds an average of $4/input ton to gross costs. RDF revenue is worth
around $2/input ton more due to decreased handling charges for a net increase of $2 per ton.
u>
Ul
-------
TABLE A-7
RESOURCE RECOVERY - DEDICATED BOILER
MSW— r>
Unloading
and
Storage
Primary
Shredder
Air
Classifier
lights
Secondary
Shredder
1
Heavies
h
Combustion
Chamber
^
F
Boiler
APC
1
To
Atmosphere
Ferrous
Recovery
Trommel
1
Ferrous
Metals
w
Aluminum
Recovery
k.
Glass
Recovery
Residue
to
Landfill
1 1
Aluminum Gullet
i
• Systen Economics based on Sources and Assumptions shown below:
Range Range-Annual
Capital/TPD Cost/Ton
24,000-48,000 18.
• Gordian Estimate for
TPD Capital
250
400
1000
13,000
16,750
32,000
Avg. -Annual Range-Revenue/Ton Avg . -Revenue/Ton
Cost/Ton Materials Energy Materials Energy
00-40.00 31.00 .90-5.80 7.00-25.00 3.40
3 facility sizes
Annual Cost — $/Ton
Capital
Process Boiler
8.60
6.90
4.60
7.40
6.00
5.25
O&M
Process
10.40
9.10
8.40
Boiler
14.60
12.00
11.75
Total
40.00
34.00
30.00
18.00
Revenue/Ton
Materials Energy
3.40
3.40
3.40
18.00
18.00
18.00
Avg. Net
Cost/Ton
9.60
Net Cost/Ton
18.60
12.60
8.60
Assumptions:
Materials revenue assumptions are same as for earlier systems.
Waterwall systems. Capital is amortized over 20 years at 7%.
Steam revenue is the same as for
* Source: 1, 4, 9, 10, 6, 5.
-------
TABLE A-8
RESOURCE RECOVERY - MODULAR INCINERATOR
ucu .... *
Unloading
and
Storage
Batch
Feed
Primary
Combv
Chan
is t ion
»ber
•
Secondary
Gas
Combustion
Chamber
».
Waste
Heat
Boiler
1
fc
APC
To
Atmosphere
Residue to Landfill
Steam
• System Economics based on Sources and Assumptions shown below:
Range
Capital/TPD
Range-Annual
Cost/Ton
20,000-30,000 12.00-22.00
Avg.-Annual
Cost/Ton
15.50
Range-Revenue/Ton
Materials Energy
NA
6-15.00
Avg.-Revenue/Ton
Materials Energy
NA
9.00
Avg. Net
Cost/Ton
6.50
• Gordian Estimate for 3 facility sizes
TPD
Capital Annual Cost — $/Ton
(x 1000) Capital O&M Total
360 11.00 9.50 20.50
1,250 7.50 9.00 16.50
2,000 6.00 8.00 14.00
Revenue — $/Ton
Materials Energy
NA
NA
NA
9.00
9.00
9.00
Net Cost — $/Ton
11.50
7.50
5.00
Assumptions :
Materials recovery is possible with this system, but as it is not a common practice it is not
considered here. Revenues from steam sales are based on boiler efficiencies capable of pro-
ducing 4000 Ibs. of low pressure steam per ton/input waste with sales pegged to $3/ thousand
Ibs. with an average 25% incentive discount. Capital is amortized over 20 years at 7%.
Source: 5, 13, 16.
-------
TABLE A-9
RESOURCE RECOVERY - PYROLYSIS
MSU ^
Unloading
and
Storage
^ Shredding -
1
i
Ferrous
Metals
Pyrolysis
^ Chamber
1
1
Residue
for Resale
or Landfill
bi
Secondary
Heat
Process
|, Apr fr- Tri Afm"c!pl1fiT''i
1
1
Pyrolysis
Fuel
Product
• System Economics based on Sources and Assumptions shown below:
Range
Capital/TPD
Range-Annual
Cost/Ton
20,000-50,000 15.00-40.00
Avg.-Annual
Cost/Ton
24.00
Range-Revenue/Ton
Materials Energy
Avg.-Revenue/Ton
Materials Energy
0-3.00 5.00-19.00 2.00
9.00
Avg. Net
Cost/Ton
13.00
Gordian Estimate for 3 facility sizes
Capital Annual Cost — $/Ton
TPD (x 1000) Capital O&M Total
250 12,500 15.50 16.50 32.00
400 16,000 12.25 15.75 28.00
1000 33,600 10.25 13.75 24.00
Revenue — $/Ton
Materials Energy
1.70
1.70
1.70
9.00
9.00
9.00
Net Cost — $/Ton
21.30
17.30
13.30
• Assumptions:
The system shown here represents a generalized composite of the various pyrolysis systems cur-
rently under development. Costs and revenues are similarly generalized. Most systems require
processing of the MSW, including ferrous recovery, prior to pyrolizing. Therefore, materials
revenues are based on $1.50/ton of metals plus a $l/ton value for slag and frit type residues
as road bed material. Energy revenues are derived from EPA estimate of Btu contents of pyroly-
sis fuel products (gas, oil) compared to current market prices of the corresponding fossil fuel
($1.60/mil Btu-gas, $2.40/mil Btu-oil) less a 10% handling charge. Capital has been amortized
over 20 years at 7%.
* Source: 1, 3, 4, 6, 7, 11, 12.
-------
139
REFERENCES FOR APPENDIX A
1. Raytheon Service Co. Resource recovery for municipal solid waste:
an overview of the 1978 proceedings of the 6th mineral waste util-
ization symposium. Lexington, Massachusetts, Raytheon Service Co.,
May 1978.
2. Smith, Frank. Resource recovery plant cost estimates: a compara-
tive evaluation of four recent dry shredding designs. U.S. Environ-
mental Protection Agency publication 530/SW-163. Washington, U.S.
Government Printing Office, July 1975.
3. U.S. Environmental Protection Agency. Resource recovery plant im-
plementation: technologies. U.S. Environmental Protection Agency
publication SW-157.2. Washington, U.S. Government Printing Office,
1976.
A. Ralph M. Parsons Co. Engineering and economics analysis of waste
to energy systems. U.S. Environmental Protection Agency publication
600-17-78-086. Washington, U.S. Government Printing Office, May
1978.
5. Gordian Associates Incorporated. Overcoming institutional barriers
to solid waste utilization as an energy source. U.S. Federal Energy
Administration publication CO-04-50172-00. Washington, U.S. Govern-
ment Printing Office, January 1977.
6. Bechtel Corporation. Fuels from municipal refuse for utilities:
technology assessment. Palo Alto, California, Electric Power Research
Institute, publication 261-1, March 1975.
7. Roy F. Weston, Inc. A review of techniques for incineration of sew-
age sludge with solid wastes. U.S. Environmental Protection Agency
publication 600/2-76-288. Washington, U.S. Government Printing
Office, December 1976.
8. Weinstein, N. and Tore, R. Costs for thermal processing of solid
wastes. Public Works, May 1976.
9. Oak Ridge National Laboratories and Argonne National Laboratory.
Solid waste utilization - incineration with heat recovery. Stony
Brook, New York, April 1978.
10. C-E Inc. Prepared vs. unprepared refuse fired steam generators.
Presented at Conversion of Refuse to Energy, First International
Conference and Technical Exhibition, November 1875.
-------
140
11. Schultz, H. Energy from municipal refuse: a comparison of ten
processes. Professional Engineer, November 1975.
12. Brown and Caldwell. Solid waste resource recovery study - Central
Contra Costa Sanitary District. San Francisco, Brown and Caldwell,
August 1974.
13. Ross Hoffman Associates. Evaluation of small modular incinerators
in municipal plants. U.S. Environmental Protection Agency publi-
cation SW-113-c. Washington, U.S. Government Printing Agency, 1976.
14. Maryland Environmental Service. Energy from wastes. Annapolis,
Maryland, Maryland Environmental Service, June 1978.
15. National Center for Resource Recovery. RDF and d-rdf. Washington,
NCRR publication 77-2, June 1978.
16. National Center for Resource Recovery. Cost analysis for the New
Orleans resource recovery and disposal program. Washington, NCRR,
1974.
17. Urban Services Group. Draft final report, Metropolitan Washington
Waste Management Agency resource recovery implementation assistance
project. Washington, D.C., Urban Services Group, June 15, 1976.
18. National Center for Resource Recovery. Resource recovery engineer-
ing and feasibility study for the 1-95 complex. Washington, NCRR,
1975.
19. Consoer, Townsend & Associates. Preliminary engineering report/
solid waste disposal system for Western Lake Superior Sanitary Dis-
trict. Chicago, Consoer, Townsend & Associates, 1974.
20. Resource Planning Associates, Inc. Assessment of alternative finan-
cing methods for solid waste facilities and equipment. Volume I.
Cambridge, Massachusetts, Resource Planning Associates, May 1973.
21. Wilson, David G., editor. Handbook for solid waste management.
New York, Van Nostrand Reinhold Company, 1976.
22. U.S. Environmental Protection Agency. Cost estimating handbook for
transfer, shredding and sanitary landfilling of solid waste. U.S.
Environmental Protection Agency publication SW-124c. Washington,
U.S. Government Printing Office, 1976.
23. U.S. Environmental Protection Agency. Composting at Johnson City:
final report. U.S. Environmental Protection Agency publication
SW-31r.2. Washington, U.S. Government Printing Office, 1975.
-------
141
24. Salem, Virginia Steam Contract, Auburn, Maine Steam Contract.
25. Energy Information Administration. Monthly energy review. Wash-
ington, U.S. Department of Energy, August 1978.
26. Minelich, D. Breakeven economics of resource recovery systems.
Paper presented at the Fifth Mineral Waste Utilization Symposium.
Tulsa, Oklahoma, Williams Brothers Urban Ore, Inc., April 1976.
27. Hecklinger, R., Velzy Associates. The relative value of energy
derived from municipal refuse. The American City, August 1975.
28. Greenberg, Zollen, and Gordian Associates Inc. Composition and
size distributions of particles released in refuse incineration.
Environmental Science and Technology, May 1978.
29. U.S. Environmental Protection Agency. Composting sewage sludge by
high rate suction aeration techniques. U.S. Environmental Protec-
tion Agency publication SW-614d. Washington, U.S. Government
Printing Office, 1977.
30. Agricultural Research Service. Cost of sludge composting. Wash-
ington, U.S. Department of Agriculture, 1977.
31. Black & Veatch and Franklin Associates Ltd. Detailed technical
and economic analysis of selected resource recovery systems. Kan-
sas City, Black & Veatch, 1978.
-------
142
APPENDIX B. MUNICIPAL SEWAGE SLUDGE ECONOMIC DATA
-------
143
Methodology. Cost estimates for various representative sludge pro-
cessing trains were developed by aggregating the costs for each unit
process within the train. A summary of these cost estimates is displayed
in Table B-l. Tables B-2 through B-13 display the total estimated capital
and operating costs and relevant assumptions for each of the unit proces-
ses. These unit costs are aggregated into process trains in Tables B-l4
through B-23, in order to derive an estimated cost per ton of dry solids
for each of the various processing options. Specific assumptions re-
lating to adjustments or deviations resulting from the aggregation of the
unit costs are also presented in Tables B-14 through B-23.
Primary reliance was placed upon cost curves developed by Consoer,
Townsend & Associates in their report for Nassau County, New York facil-
ities planning. The estimates reflect November 1977 costs in the New
York area, and are based on the following assumptions:
• Operation and maintenance costs, unless otherwise specified,
include labor, power, materials and chemical costs.
• Power costs are estimated at $0.05 per IcWh.
• Labor costs are estimated to be $8.35 per hour, including
fringe benefits.
• Fuel oil and gasoline are estimated at $0.37 per gallon and
$0.60 per gallon, respectively.
• Chemical costs of $0.02 per Ib. for lime and $0.10 per Ib.
for ferric chloride were assumed.
• Construction costs are based upon an ENR index of 3108.
• Capital costs are amortized over 20 years at 7 percent interest.
• Level of reliability of the estimates equals + 30 percent.
-------
TABLE B-l
SUMMARY OF SLUDGE DISPOSAL COSTS*,t
Disposal
Alternatives
OPTION 1:
A
B
OPTION 2:
A
B
OPTION 3:
A
B
OPTION 4:
OPTION 5:
OPTION 6:
OPTION 7:
Capital Costs
($ x 103)
10 50 100
TPD TPD TPD
3,250
5,105
4,500
6,355
4,500
6,355
2,019
2,020
3,066
1,210
10,000
11,050
11,800
12,850
13,200
14,250
6,570
6,370
9,666
4,500
18,500
16,350
19,500
17,350
24,500
22,350
12,700
11,600
16,633
9,200
Annual
Operating Costs
($ x 10')
10 50 100
TPD TPD TPD
730
839
747
876
836
1,045
586
485
716
460
2,781
2,821
2,412
2,556
2,688
3,232
2,001
1,673
2,834
1,705
5,118
4,765
4,295
4,151
4,995
5,451
3,713
2,794
5,198
2,978
Total Cost
($/Ton)
10 50
TPD TPD
200
230
205
240
230
265
161
133
198
126
153
155
132
140
148
156
113
92
156
94
100
TPD
140
131
117
113
137
133
101
76
144
81
Net Cost
Revenue ($/Ton)
Potential 10 50 100
($/Ton) TPD TPD TPD
200
230
205
240
230
265
161
133
20 178
126
153
155
132
140
148
156
113
92
136
94
140
131
117
113
137
133
101
76
124
81
* Source: Gordian Associates Incorporated.
t All values are stated as 1978 dollars per dry ton of solids.
-------
Costs:
TABLE B-2
UNIT PROCESS ECONOMICS - VACUUM FILTRATION
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
850
3000
6000
Annual Costs
($ x 103)
Capital Operating Total
76
270
540
200
800
1250
276
1070
1790
Cost Per
Day ($)
756
2932
4904
Cost Per Ton
Dry Solids
($)
75.60
58.64
49.04
Assumptions:
- Capital costs include pumps, internal piping and electrical controls, mechanical equipment,
conveyors, sludge-cake storage hopper, and buildings.
- Operating costs include costs of chemical conditioning, chemical costs of $0.10/lb for
and $0.02/lb for CaO. FeCl3 additions @ 25% by weight, CaO @ 10% by weight.
* Source: Consoer, Townsend & Associates
-------
TABLE B-3
UNIT PROCESS ECONOMICS - MULTIPLE HEARTH INCINERATION (SLUDGE SOLIDS @ 20%)*
Costs:
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
2400
7000
12,500
Annual Costs
($ x 103)
Capital Operating Total
216
630
1125
238
1081
2203
454
1711
3328
Cost Per
Day ($)
1243
4687
9118
Cost Per Ton
Dry Solids
($)
124.00
93.74
91.18
Assumptions;
- Dewatering in vacuum filter to 20% solids prior to incineration is assumed but not included
in cost estimates.
- Sludge contains 10,000 Btus per Ib. dry solids, 75% volatile solids.
- Two units are used for 100% standby at average operating conditions.
- Maintenance and supplies estimated to be 6% of major equipment costs.
- Ash equals 30% of total dry solids by weight and costs $15/ton for hauling and disposal.
* Source: Consoer, Townsend & Associates
and Gordian Assoicates Incorporated.
-------
Costs:
TABLE B-4
UNIT PROCESSING ECONOMICS - FILTER PRESS*
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
2100
4800
7000
Annual Costs
($ x 103)
Capital Operating Total
189
432
630
180
650
1100
369
1082
1730
Cost Per
Day ($)
1011
2964
4739
Cost Per Ton
Dry Solids
($)
101.10
59.30
47.39
Assumptions:
- Capital costs include filter presses, pressure pumps, conveyor equipment, sludge storage tanks,
and buildings.
- Operating costs include cost of chemical conditioning. Chemical additions for FeCl3@ 2.5% by
weight, CaO @ 10% by weight, for raw sludge. Chemical costs of $0.10/lb for FeCl3 and $0.02/3lb.
for CaO.
- Filter press results in sludge solids content of 35%.
* Source: Consoer, Townsend & Associates
-------
TABLE B-5
UNIT PROCESS ECONOMICS - MULTIPLE HEARTH INCINERATION (SLUDGE SOLIDS @ 35%)*
Costs:
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
2400
7000
12,500
Annual Costs
($ x 103)
Capital Operating Total
216
630
1125
162
700
1440
378
1330
2565
Cost Per
Day ($)
1036
3644
7027
Cost Per Ton
Dry Solids
($)
103.60
72.88
70.27
Assumptions;
- Dewatering in filter presses to 35% solids prior to incineration is assumed but not included
in cost estimates.
- Sludge contains 10,000 Btus per Ib. dry solids, 75% volatile solids.
- Two units are used for 100% standby at average operating conditions.
- Maintenance and supplies estimated to be 6% of major equipment costs.
- Ash equals 30% of total dry solids by weight and costs $15/ton for hauling and disposal.
* Source: Consoer, Townsend & Associates
and Gordian Associates Incorporated
-------
TABLE B-6
UNIT PROCESSING ECONOMICS - FLUIDIZED BED INCINERATION (SLUDGE SOLIDS @ 20%)*
Costs:
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
4255
8050
10,350
Annual Costs
($ x 103)
Capital Operating Total
382
724
931
181
1027
2044
563
1751
2975
Cost Per
Day ($)
1542
4797
8150
Cost Per Ton
Dry Solids
($)
154.00
96.00
82.00
Assumptions:
- Dewatering in vacuum filter to 20% solids prior to incineration is assumed but not included
in cost estimates.
- Sludge contains 10,000 Btus per Ib. dry solids, 75% volatile solids.
- Two units are used for 100% standby at average operating conditions.
- Waste heat used as combustion air pre-heat.
- Maintenance and supplies estimated to be 6% of major equipment costs.
- Ash equals 30% of total dry solids by weight and costs $15/ton for hauling and disposal.
* Source: Consoer, Townsend & Associates
and Gordian Associates Incorporated
-------
TABLE B-7
UNIT PROCESSING ECONOMICS - FLUIDIZED BED INCINERATION (SLUDGE SOLIDS @ 35%)*
Costs:
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
4255
8050
10,350
Annual Costs
($ x 103)
Capital Operating Total
382
724
931
125
750
1490
507
1474
2421
Cost Per
Day ($)
1389
4038
6632
Cost Per Ton
Dry Solids
($)
138.90
81.00
66.32
Assumptions:
- Dewatering in filter process to 35% solids prior to incineration is assumed but not included in
cost estimates.
- Sludge contains 10,000 Btus per Ib. of dry solids, 75% volatile solids.
- Waste heat used as combustion air pre-heat.
- Maintenance and supplies estimated to be 6% of major equipment costs.
- Ash equals 30% of total dry solids by weight and costs $15/ton for hauling and disposal.
* Source: Consoer, Townsend & Associates
and Gordian Associates Incorporated
-------
Costs:
TABLE B-8
UNIT PROCESSING ECONOMICS - THERMAL CONDITIONING*
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
1250
3200
6000
Annual Costs
($ x 103)
Capital Operating Total
112
288
540
150
400
700
262
688
1240
Cost Per
Day ($)
719
1885
3397
Cost Per Ton
Dry Solids
($)
71.90
37.70
33.97
Assumptions:
- Capital costs include: sludge feed pumps, grinders, heat exchangers, reactors, boilers, gas
separators, and buildings.
* Source: Consoer, Townsend & Associates
-------
Costs:
TABLE B-9
UNIT PROCESSING ECONOMICS - AEROBIC DIGESTION*
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
999
3200
6200
Annual Costs
($ x 103)
Capital Operating Total
90
288
558
125
440
950
215
728
1508
Cost Per
Day ($)
588
1994
4131
Cost Per Ton
Dry Solids
($)
58.80
40.00
41.31
Assumptions;
- Capital costs include basins (20 day detention time) and floating mechanical aerators.
- Mixing requirements: 134 hp/mg
- Oxygen requirements: 1.6 Ibs 02/lb VSS destroyed.
* Source: Consoer, Townsend & Associates
-------
Costs:
TABLE B-10
UNIT PROCESSING ECONOMICS - ANAEROBIC DIGESTION (TWO STAGE)*
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
1000
3000
5100
Annual Costs
($ x 103)
Capital Operating Total
90
270
459
24
70
130
114
340
589
Cost Per
Day ($)
312
932
1613
Cost Per Ton
Dry Solids
($)
31.20
18.64
16.13
Assumptions:
- Capital costs include digestor, heat exchanger, gas collection equipment, control building.
- Feed to digesters is combined primary/WAS and is thickened.
- Feed - 1,900 Ib/mg. at 4% solids (75% volatile)
- Loading rate of 0.16 Ib/cu. ft./day.
- Operating temperature of 85-110°F.
- Credit is taken for using digestor gas for heating.
* Source: Consoer, Townsend & Associates
-------
Costs:
TABLE B-ll
UNIT PROCESSING ECONOMICS - LANDFILLING*
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
170
370
500
Annual Costs
($ x 103)
Capital Operating Total
15
33
45
80
230
370
95
263
415
Cost Per
Day ($)
260
720
1136
Cost Per Ton
Dry Solids
($)
26.00
14
11.36
Assumptions:
- Construction costs include site preparation, front end loaders, monitoring wells, fencing and
leachate collection and treatment.
- Operating and maintenance costs are based on landfilling digested biological sludge at 20% solids.
- Costs do not include land purchase or lease, or costs to transport the dewatered sludge.
* Source: Consoer, Townsend & Associates
-------
TABLE B-12
UNIT PROCESS ECONOMICS - HEAT DRYING*
Costs:
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
966
4866
9633
Annual Costs
($ x 103)
Capital Operating Total
87
438
867
260
1314
2601
347
1752
3468
Cost Per
Day ($)
950
4800
9501
Cost Per Ton
Dry Solids
($)
95
95
95
Assumptions:
- Dewatering in vacuum filters prior to drying is assumed but not included in cost estimate.
- Maintenance and supplies are estimated to be 6% of major equipment costs.
- Potential economies of scale are not included, due to data limitations.
* Source: Consoer, Townsend & Associates
-------
Costs:
TABLE B-13
UNIT PROCESSING ECONOMICS - COMPOSTING *
Capacity
(Tons Per Day
Dry Solids)
10
50
100
Total Capital
Costs ($ x 103)
360
1500
3200
Annual Costs
($ x 103)
Capital Operating Total
32
135
288
152
500
900
184
635
1188
Cost Per
Day ($)
504
1740
3254
Cost Per Ton
Dry Solids
($)
50.4
34.8
32.5
Assumptions;
- Sludge cake solids content at 20%.
- Capital costs include site construction, but do not include land
- Capital costs amortized over 20 years at 7%.
* Source: Consoer, Townsend & Associates
-------
TABLE B-14
OPTION 1-A*
Sludge
^
w
Chemical
Processing
w
Vacuum
Filtration
w\
Incineration
in MHF
I
Ash to
Landfill
System Economics ($/Ton Dry Solids)
Sludge Input
(TPD)
10
50
100
Assumptions:
t
t
t
76
59
49
124
94
91
- Ash disposal costs are included in incineration costs.
- Vacuum filtration results in sludge cake of 20% solids.
Total Cost
($/Ton Dry Solids)
200
153
140
* Source: Consoer, Townsend & Associates, Nassau county, new york sludge management study, and
Gordian Associates Incorporated.
t Included in dewatering costs.
Ul
-------
TABLE B-15
OPTION 1-B*
Sludge
9
Chemical
Processing
fc,
Vacuum
Filtration
H
Incineration
in FBF
i
Ash to
Landfill
System Economics ($/Ton Dry Solids)
Sludge Input
(TPD)
10
50
100
t
t
t
76
59
49
Assumptions;
154
96
82
- Ash disposal costs are included in incineration costs.
- Vacuum filtration results in sludge cake of 20% solids.
- Fluidized bed incinerator includes combustion air preheater
Total Cost
($/Ton Dry Solids)
230
155
131
* Source: Consoer, Townsend & Associates, Nassau county, new york sludge management study, and
Gordian Associates Incorporated.
Included in dewatering costs.
-------
TABLE B-16
OPTION 2-A*
Sludge
t
Chemical
Processing
w
Filter
Press
r ^
Incineration
in HHF
!
Ash to
Landfill
System Economics ($/Ton Dry Solids)
Sludge Input
(TPD)
10
50
100
t
t
t
101
59
47
104
73
70
Total Costs
($/Ton Dry Solids)
205
132
117
Assumptions;
- Ash disposal costs included in incineration costs.
- Filter press results in sludge cake of 35% solids.
* Source: Consoer, Townsend & Associates, Nassau County, new york sludge management study, and
Gordian Associates Incorporated.
t Included in dewatering costs.
Ln
-------
TABLE B-17
OPTION 2-B*
Sludge
K
Chemical
Processing
^
w
Filter
Press
^
w
Incineration
in FBF
]
AcV. !-,->
Landfill
System Economics ($/Ton Dry Solids)
Sludge Input
(TPD)
10
50
100
t
t
t
101
59
47
139
81
66
Total Costs
($/Ton Dry Solids)
240
140
113
Assumptions:
- Ash disposal costs included in incineration costs.
- Filter press results in sludge cake of 35% solids.
- Fluidized bed incinerator includes combustion air preheater.
* Source: Consoer, Townsend & Associates, Nassau County, new york sludge management study, and
Gordian Associates Incorporated.
Included in dewatering costs.
-------
TABLE B-18
OPTION 3-A*
Sludge Handling Process
Sludge
Thermal
Conditioning
Vacuum
Filtration
Incineration
in MHF
Ash to
Landfill
System Economics ($/Ton Dry Solids)
Sludge Input
(TPD)
10 72
50 38
100 34
54
37
33
104
73
70
Total Cost
($/Ton Dry Solids)
230
148
137
Assumptions:
- Ash disposal costs included in incineration costs.
- Vacuum filtration results in sludge cake of 35% solids following thermal conditioning.
- Additional treatment costs for waste liquor are included in costs for thermal conditioning
* Source: Consoer, Townsend & Associates, assau ounty, new york sludge management study.
-------
TABLE B-19
OPTION 3-B*
Sludge Handling Process
Sludge
hi
w
Thermal
Conditioning
t
Vacuum
Filtration
^
Incineration
in FBF
;
Ash to
Landfill
System Economics ($/Ton Dry Solids)
Sludge Input
(TPD)
10
50
100
72
38
34
54
37
33
139
31
66
Total Cost
($/Ton Dry Solids)
265
156
133
Assumptions;
- Ash disposal costs included in incineration costs.
- Vacuum filtration results in sludge cake of 35% solids following thermal conditioning.
- Additional treatment costs for waste liquor are included in costs for thermal conditioning
* Source: Consoer, Townsend & Associates, Nassau county, new york sludge management study.
-------
TABLE B-20
OPTION 4*
Sludge Handling Process
Sludge
fc
Aerobic
Digestion
Chemical
Conditioning
^
Vacuum
Filter
^
Landfill or
Land Spread
System Economics ($/Ton Dry Solids)
Sludge Input
(TPD)
Total Cost
($/Ton Dry Solids)
10
50
100
59
40
41
t
t
t
76
59
49
26
14
11
161
113
101
* Source: Consoer, Townsend & Associates, Naussau county, new york sludge management study, and
Gordian Associates Incorporated
•f' Included in dewatering costs.
-------
TABLE B-21
OPTION 5*
Sludge Handling Process
Sludge
kw
Anerobic
Digestion
w
Chemical
Conditioning
k.
Vacuum
Filter
w
Landfill or
Land Spread
System Economics ($/Ton Dry Solids)
Sludge Input
(TPD)
Total Cost
($/Ton Dry Solids)
10
50
100
31
19
16
t
t
t
76
59
49
26
14
11
133
92
76
* Source: Consoer, Townsend & Associates, Naussau county, new york sludge management study, and
Gordian Associates Incorporated
t Included in dewatering costs.
-------
TABLE B-22
OPTION 6*
Sludge Handling Process
Sludge h Chemical k Fj
o -. p „ p
uona 1 1 loning 1 1
System Economics ($/Ton Dry Solids) :
Sludge Input
(TPD)
10 t
50 t
100 t
Assumptions:
liter k Flash * Distribution
P w
Total Cost
($/Ton Dry Solids)
101 95 2 198
59 95 2 156
47 95 2 144
Cost estimates do not reflect possible economies of scale in heat-drying operations.
* Source: Consoer, Townsend & Associates, Nassau county, new york sludge management study, and
Gordian Associates Incorporated.
+ Included in dewatering costs.
-------
Sludge Handling Process
TABLE B-23
OPTION 7*
Sludge
ik
Chemical
Conditioning
K
Vacuum
Filter
tf
Composting
w
Distribution
System Economics ($/Ton Dry Solids);
Sludge Input
(TPD)
Total Cost
($/Ton Dry Solids)
10
50
100
t
t
t
76
59
49
50
35
32
0
0
0
126
94
81
* Source: Consoer, Townsend & Associates, Nassau county, new york sludge management study, and
Gordian Associates Incorporated.
t Included in dewatering costs.
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167
APPENDIX C. SLUDGE DISPOSAL PLANNING ACTIVITIES
OF OCEAN DUMPING COMMUNITIES
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168
Permittee: Bergen County, New Jersey Sewerage Authority
Little Ferry, New Jersey
Status of Plans;
Codisposal has been examined as an alternative sludge
disposal option to ocean dumping, and is seen as the most
desirable system in the long run.
The County has been looking at the Union-Carbide Purox
System (including electrical generation).
Composting will be pursued as an interim solution, until
the codisposal system can be set up.
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169
Permittee; Linden Roselle-Rahway Valley Sewage Authority.
New Jersey
Status of Plans;
The disposal alternative which has been chosen is sludge
composting. The sludge from both Linden, N.J. and Rahway, N.J.
would be composted together.
As a back-up to composting, two alternatives were examined:
1. Dewatering sludge to 28 to 32 percent moisture and
landfilling, and
2. Codisposal of sludge and solid waste in refuse-fired
modular combustion units, using low temperature
pyrolysis.
The units would be fired directly with part of the solid
waste from Linden. The refuse is currently landfilled at a
site which is approximately the same distance away as the
sewage treatment plant. All sorting would be done at the
incinerator, during feeding. The major disadvantage to this
proposal relates to anticipated air quality problems.
Some rough cost calculations have been developed to back
up this alternative. However, the planning for codisposal is
still in the pre-proposal stage, and the cost figures are not
considered reliable at this time.
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170
Permittee: Passaic Valley Sewerage Commission
Newark, New Jersey
Status of Plans:
Passaic Valley is in the process of developing feasibility
studies. A number of codisposal projects are being examined,
including:
1. Disposal of sewage sludge and solid waste through an
industrial park operated by the New York-New Jersey
Port Authority. The park would use sludge and solid
waste to generate electricity and for resource re-
covery. The planning is still in the initial stages,
and additional authority will have to be obtained.
2. Cooperation with the Essex County Improvement Authority
(no details).
3. Public Service Electric and Gas. Co. (PSE&G): Passaic
Valley has entered into a contract with PSE&G to
determine the feasibility of burning sludge with coal
in utility boilers.
Codisposal would be the preferred alternative, if one of
the systems could be worked out in time for the 19.81 deadline.
If not, the alternative would be sludge combustion in their
own combustion facilities, since there is not enough land to
compost. In either case, there is concern about compliance with
the Clean Air Act.
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171
Permittee: Middlesex County Sewage Authority,
New Jersey
Status of Plans:
Sludge incineratin in MHFs has been proposed as an alternative
to ocean dumping.
Codisposal was evaluated and was considered a good alternative
except for the institutional problems. These include:
1. Obtaining authority over solid waste;
2. Allocating costs and charges between solid waste and
sewage treatment;
3. Cost of solid waste management would double (solid
waste currently landfilled at $3 per ton);
4. Funding - sole purpose sludge management facilities
are eligible for 75 percent federal, 8 percent state
funding. Since solid waste facilities are not eligible
for funding assistance, implementation of a codisposal
system would depend on being able to propose a self-
supporting solid waste facility that can be financed.
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172
Permittee: Nassau County Department of Public Works
East Rockaway, New Jersey
Status of Plans:
Two codisposal options have been considered:
1. Participation in the Glen Cove codisposal project
which is pending construction.
2. Use of sludge in Hempstead resource recovery project
(pilot testing currently being conducted in Franklin,
Ohio).
Pilot studes are also being conducted for composting and
landfilling.
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173
Permittee: Department of Environmental Facilities
Westchester County, New York
Status of Plans:
Westchester County has completed a 201 study which evaluated
codisposal as an alternative to ocean dumping, but found that it
was not economic due to transportation costs. According to their
analyses, a codisposal option would be economically viable only
if the incineration units were located close to the sewage treat-
ment plant. However, air quality standards currently preclude
the siting of incinerators in the area of the sewage treatment
plant. Consequently, codisposal has been removed from consider-
ation.
Currently plans for solid waste disposal recommend a resource
recovery project, including generation of steam electricity.
Current plans for sludge disposal involve composting. Both of
these plans are being re-evaluated.
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174
APPENDIX D. CODISPOSAL AT KREFELD, WEST GERMANY
-------
175
CODISPOSAL AT KREFELD. WEST GERMANY
THE MODERN ALTERNATIVE TO OCEAN DUMPING OF SEWAGE SLUDGE*
By Klaus S. Feindler**
ABSTRACT:
Codisposal, especially when combined with energy and/or materials recovery,
has proven to be a highly successful sewage sludge disposal technique in
Europe. The Krefeld, West Germany Codisposal and Refuse Power Plant (C-RPP)
is singled out for an in-depth review because of its highly advanced air pol-
lution control system. West German emission standards for gaseous and parti-
culate pollutions are discussed because, being considered as the most stringent
in the world today, they had a profound influence on the design of the Krefeld
C-RPP.
The special problems associated with complete combustion of sewage sludge
are discussed, and mention is made of the U.S.-DOE grant for Krefeld which is
to develop a complete balance of all pollutants which may result from the co-
disposal of municipal refuse and sewage sludge.
INTRODUCTION:
As a consequence of the U.S.-EPA ban on ocean dumping of municipal sewage
sludge after 1981, alternative methods of disposal such as landfilling, com-
posting and incineration are receiving renewed attention. This re-evaluation
of older and previously established disposal methods coincides with the search
for affordable and reliable methods of resource recovery from refuse.
It is, therefore, a logical approach to consider codisposal, i.e. the
simultaneous processing of sludge and refuse in the same facility as a most
promising alternative to ocean dumping. The generation of sludge and refuse
alike is simply the direct result of our daily human activities. Their dis-
posal is difficult, complex and costly, and, when viewed together with the con-
comitant issues of energy conservation and environmental protection, they tend
to exert great pressures upon our society. This is particularly true in the
urban areas of high population concentrations.
It is then no coincidence that several localities in the Mid-Atlantic
States section of the U.S. are severely affected. The municipalities of Glen
Cove, Nassau County, New York City, Newark, Philadelphia, and Westchester
County, among others, are now clamoring to develop plans to comply with the EPA
ban.
THE EUROPEAN CODISPOSAL EXPERIENCE:
Codisposal, even when combined with energy and/or materials recovery, is
not an entirely new idea, since a number of such facilities were built in the
U.S., in Asia and especially in Europe during the post-World War II period.
While U.S. facilities were generally small in size and largely unsuccess-
ful in their operation, Europe, on the other hand, has produced a number of
facilities in a rather wide range of sizes from 100 to 2,000 STPD (short tons
per day) processing capacity. (See Reference 1)
Most significant is the fact that_these_European jDlants_are_oj>erating_ _
*Mid-Atlantic States Section of the Air Pollution Control Assoc. Semi-Annual
Technical Conference, Hilton Gateway, Newark, N.J., April 27, 1979.
^President of Quantum Associates, a consulting firm concerned with resource
recovery, and formerly Technical Director of Grumman Ecosystems Corporation.
-------
successfully up to date, and therefore, it is appropriate to review the 176
European codisposal experience and to determine its applicability to U.S.
conditions.
The European codisposal facilities employ predominantly two successful
technologies: co-composting and co-incineration. While composting is con-
sidered by most as a simple and inexpensive approach, it has demonstrated per-
sistent marketing problems with its product materials. In most recent times,
due to the progressive sewering of industrial and commercial neighborhoods, it
r.as suffered greatly from the uncertainties which surround the fate of the
heavy metals. Its critics have charged that through the agricultural use of
compost produced by codisposal, heavy metals enter the food chain and endanger
human health.
Incineration systems, by comparison, have proliferated in Europe in spite
of the fact that they are both capital and energy intensive and unless properly
designed, can have major environmental impacts.
Depending on planning objectives, codisposal plants of the co-incineration
type range from mere disposal to full fledged resource recovery. The first ap-
proach simply uses refuse as the fuel to support destruction of the sludge;
it often requires auxiliary fuel to compensate for moisture fluctuations in
the sludge, and perhaps more significantly, in the refuse. These systems,
while less sophisticated and capital intensive, face exceedingly higher opera-
ting costs, a fact which relates to their failure to recover energy and/or
materials in order to generate off-setting revenues.
Examples are: Horsens, Reigate, Nieder-Uzwil
A second type provides boilers mounted over, or after, the basic incinera-
tion device called grates to use the thermal energy released during the com-
bustion of refuse for steam production. The resulting steam, in turn, is then
used to dry the sludge prior to its incineration or in some cases, pasteurize
a portion of the feed sludge if it is to be used for agricultural purposes
rather than for incineration. This type, due to flue gas cooling by the boilers,
permits the use of more advanced air pollution control systems. However,
this type is confined to small to medium sized installations.
Examples are: Dieppe, Deauville, Drive
Finally, a third type called "Codisposal - Refuse Power Plants," or C-RPP's,
addresses the real needs of the large urban areas for nearby and centrally lo-
cated facilities with high daily processing capacities. In these C-RPP's sludge
is dried by direct contact with hot flue gases to the point of its conversion
to a fuel which is also called "Sludge Derived Fuel," or SDF, which at a solid
concentration of 95%, or more, and with a heating value of 8,000 to 10,000
Btu/Lb resembles low quality coal. This SDF is then fired in suspension in a
zone downstream of, and separate from, the grate-fired refuse. This method of
direct drying followed by suspension firing is also known as the DD-SF method.
Energy is efficiently recovered in the form of superheated steam if elec-
trical power generation and/or district heating is contemplated. Ferrous metal
is also recovered, either from the raw refuse itself, or after from the residue
resulting from combustion, in order to further enhance the resource recovery
aspects of these facilities. It is important to recognize the main distinction
which separates C-RPP's from other codisposal/co-incineration approaches: thermal
and/or electrical energy is exported for sale to external customers.
Table I lists the more important C-RPP's of the DD-SF type and indicates
their technology status.
In this regard, the recent award by the City of Munich in West Germany
(FRG), to build a large C-RPP of the DD-SF type must be viewed as a highly
-------
important development. Munich, a modern, large and highly commercial city,
opted to reduce its various composting operations in favor of electrical power
generation.
ENVIRONMENTAL CONCERNS ASSOCIATED WITH REFUSE POWER:
Several characteristics of major environmental significance must be asso-
ciated with the operation of Refuse Power Plants in general, and with those of
the C-RPP type in particular, regardless of the origin of their technology:
- safety and health hazards
- gaseous emissions
- liquid effluents
- residue stability
Of these four, the nature of gaseous emissions and their control should
prove to be of particular interest to the participants of this MASS-APCA con-
ference. This same point has received major attention from the regulatory
agencies in Europe and especially from those in the FRG.
Just as Table 1 shows a preponderance of C-RPP development in the FRG,
a similar table could be drawn up for plain RPP's. During the last two dec-
ades, the development trends in the FRG and the USA have become diametrically
opposed. American investigators reported installed capacities for municipal
incinerators at 50,000 STPD for 1970, 63,500 STPD for 1972 and 45,000 for
1976 respectively. Apparently, most U.S. municipalities prefer to shut down
their incinerators rather than upgrade them for compliance with new pollution
control regulations. (See Reference 2)
Just the opposite is true for the FRG, where during the last decade and
a half a great deal of new capacity has been added. (See Reference 3)
For the 1973/76 period of comparison, the FRG could boast of approximately
35,000 STPD installed capacity versus some 45,000 STPD in the U.S., a fact which
gains in importance, when one realizes the relative size of the populations
served by these systems. Thus, 62 million Germans compared with 210 million
Americans yield for 1973 a population factor of 3.4. Taking into consideration
differences in the per-capita waste generation rates, 2.7 Lb/capita-day in the
FRG versus 3.3 Lb/capita-day in the U.S., then at least in theory, up to 25.9
million people (42% of the total population) can be served by refuse incinera-
tion in the FRG versus only up to 27.3 million people (13% of the total popula-
tion) in the U.S.
Following this line of reasoning, one would expect significantly higher
emissions in the FRG, but just the reverse is true at least with two major
pollutants, CO and particulates. Inspection of Table 2 will show in the column
entitled "Emission Ratios USA/FRG" under "Incinerators" that FRG CO emissions
are almost two orders lower and that FRG particulate emissions are at least
one order of magnitude lower.
Both of these positive developments are the result of a long standing
concern in the FRG for environmental protection which is evidenced by tough
regulations which forced the development of advanced combustion techniques and/
or air pollution control systems. Changes in the composition of waste streams
are carefully monitored, and when new materials enter which cause the emission
of new pollutants, then the regulations are amended accordingly. An example
was the increase in HC1 emissions which result from the burning of plastics
delivered to the plants.
Table 3 reports on the measurement of gaseous emissions in selected European
RPP's. While particulates are well controlled by the application of high per-
formance electrostatic precipitators, the same cannot be said for HC1 and SOX.
-------
178
The FRG Federal EPA took due notice of these adverse developments and
responded by rewriting the emission standards for Refuse Power Plants. Table 4,
"Refuse Power Plants: Emission Standards - West Germany vs. U.S.A." shows the
results of T.A. Luft 1974 which is clearly more stringent than any standard
presently in force in the U.S., or for that matter, anywhere else in the world.
The regulations for C-RPP's are even tougher because of the unique physical,
chemical and biological characteristics which distinguish sludge from refuse:
the first of these is the resistance of sludge to complete burnout even under the
most favorable conditions of the three T's (temperature, time and turbulence).
Two investigators report these difficulties as follows:
"...sludge cake which has been mechanically dewatered has a pe-
culiar structure: it is a slime-like substance which is permea-
ted by fibres and particles of different sizes. If sludge in
this condition is exposed to heating, then the water contained in
the outer layer will evaporate leaving behind a felt-like and
strongly cohesive layer- While elastic and tough, this felt layer
is a very poor thermal conductor, i.e. only little of the heat can
penetrate in the still moist nucleus and effect its complete dry-
out ..." (Reference 4)
"...little data is available on the thermal diffusibility of
sludge, but assuming a value of oC= 0.02 mm^/s, the time taken
for different thicknesses of cake can be estimated from 10 to 82
minutes for 20 to 60 mm. Consequently, the centers of large pieces
of cake may still be decomposing while smaller pieces have com-
pletely burned out..." (Reference 5)
Since the mean residence time in modern RPP's firing high BTU refuse may
be taken as a typical 45 minutes there is a danger that some large pieces, un-
less well broken up at the start, could pass through the systeu without de-
composition. Such occurrences could lead to objectionable odors and microbial
hazards.
Other problems could arise in areas where raw, unprocessed sludge is
stored or transferred due to biological decomposition with accompanying odor
and/or explosion hazards.
As can be gleaned from Table 5, TA Luft 1974 contains special requirements
which deal with the unique problems of C-RPP's. An example is the storage
and transfer of sludge which must occur under negative air pressure in a manner
which permits combustion of any evolving gases and vapors at temperatures in
excess of 800° C (1,472° F).
KREFELD C-RPP; THE MODEL FOR MODERN APC SYSTEMS;
One of the plants listed, the Krefeld C-RPP, was selected for an in-depth
review as part of this paper, because its air pollution control system (APC)
is the most advanced installed in any plant anywhere.
The Krefeld C-RPP is located on the west bank of the Rhine River in
Krefeld, West Germany adjacent to the municipal sewage treatment plant. (See
Figure 1). This plant, built by VKW and started up in 1975, is considered the
most modern example of the codisposal type of plant because:
- it practices cogeneration with concomitant export of both electricity
and district heat;
- it has the first full-scale combined precipitator/wet scrubber air
pollution control systems (including desulfurization);
- it survived the tough challenges from the state licensing board in
a heavily industrialized locality with non-attainment stature; and,
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179
- it was the first plant which incorporated the patented Duesseldorf
Roller Grate System, already proven in many refuse power plants else-
where, with the HGS system.
The plant's current refuse processing capacity is 630 TPD (corresponding
to a population of about 350,000); the projected design capacity is 1,100 TPD.
The type of refuse processed is similar to that processed by the nearby
Duesseldorf refuse power plant, shown on the following table entitled, "Classi-
fication of Wastes Processed by the Duesseldorf RPP." (Table 6).
In its final configuration, the plant will also consume 510 TPD of sludge
cake at 26% TS concentration, from both sanitary and industrial services (cor-
responding to a combined population equivalent of 900,000). The plant is also
equipped to fire up to 96 TPD of waste oil, as well as certain industrial wastes.
Figures 1A, IB, 1C, ID, IE, IF, and 1G further illustrate the Krefeld
facility: Plot Plan, Plan View, Interfaces Between Municipal Services and
Private Enterprise, Major Subsystems, Codisposal System with Energy Recovery,
Flue Gas Purification Subsystem, and Sludge Processing Subsystem.
PLANT OPERATIONS:
The following discussion of the operation of the Krefeld C-RPP is keyed
to the illustration, "Sectional View of Krefeld, West Germany, Codisposal and
Refuse Power Plant," (Figure 2):
1. Refuse Processing:
The refuse handling subsystem starts with the dumping of refuse from packed
trucks and other types of vehicles (1) into the storage pit (2). The storage
pit at Krefeld is rather large, because it has extra capacity for long holiday
weekends, as well as for expansion; at present, it can hold about seven to ten
days worth of garbage. The cranes (3) lift the refuse and deposit it into the
feedchute (4) by means of hydraulic feeders(5).
The refuse is then pushed onto the roller grates at (6), where drying
takes place on the first roller and ignition on the second and third rollers.
Most of the burning is completed on the third roller, and if not, on the fourth
and fifth. The sixth roller is simply a safety provision to deal with hard to
burn objects which occasionally find their way into the waste stream. This is
a true counter flow system in that the refuse is moving downward and the fire and
hot flue gases are moving upward.
At the end of the combustion chamber, the ash drops off into the ash
quench tank. The gritlings fall through the rollers into the gritling hoppers
beneath, and they are also added to the quench tank. All of the ash is then
moved into the ash handling facility (7).
Steam is produced from the combustion of refuse in the boiler (9). This
is a multi-pass boiler (first pass, radiation shaft; second pass, superheater;
third pass, economizer).
The steam is taken out and passed through the turbo-alternators (16),
which are back-pressure machines. The steam from the outlet side of the turbo-
alternators goes into condensing-type heat exchangers. District .heat is pro-
duced in these exchangers for pipeline transmission to the steam heat customer
in a nearby industrial park.
From the condensing heat exchangers, the condensate is sent to the feed-
water storage container (18). It is returned, via feed pumps, back into the
boiler system.
The final design of the plant calls for three parallel processing systems
At the present time, only two processing lines are installed. This is the tra-
ditional method in Germany, to enable adaptation to population growth. In
-------
180
line with this traditional approach, the plant was built with only two pro-
cessing lines installed, and with enough space for a third one to be added.
Presently, two back-pressure 1.4 MW turbo-alternators are installed. The
third machine that will be installed, a condensation turbine, will be a 11.5MW
unit, for a combined total plant generating capacity of close to 14.3 MW.
Behind the feedwater storage tank (18), there is a fuel oil-fired package
boiler as well as the condensing heat exchangers, for district heat production.
The service that is provided to the steam heat user is a non-interruptible heat-
ing service; consequently, in case of a shut-down of the refuse-fired boiler,
the oil-fired package boiler serves as a back-up. The district heating capacity
is on the order of 150 to 200 million Btu per hour final capacity.
2. Sludge Processing:
The sludge is first pumped up to the centrifuges (10). At present, a
deck of four centrifuges is installed, and there is additional capacity to add
two more. The purpose of centrifuging is to wring out some of the moisture
and to bring up the solids content of the material to about 26% TS concentration.
Prior to the point of entry into the centrifuges, polyelectrolytes are metered
in as filtering or separating agents; since the object is to convert sewage
sludge into a fuel, it is desirable to increase the solids content as much
as is possible. There are two outputs from the centrifuges: the water that
has been separated, which is returned to the sewage treatment plant; and the
sludge cake in a still moist form. The sludge cake drops from the centrifuges
down to an intermediate storage and transfer system (11), which transfers it
onto various conveyors. These conveyors then lift the cake into a contact chamber
at (12) where it is exposed to hot gases that are taken out of the boiler. This
is called flash drying. The hot gases are removed from the radiation shaft of
the boiler at (13), at roughtly 1,400° F to 1,500° F. They are syphoned off and
brought down into the drying chamber, where they dry the sludge cake. The re-
sulting cake is about 95% TS concentration and 5% water residual. At this point,
the material is highly combustible. In fact, because the material is almost
too combustible for storage, the system is designed to keep it flowing and to
not let it accumulate. This cake drops down from the flash dryer into a hammer
mill, known as the HGS mill, the lowest part of the system. The purpose of
the HGS mill is to grind the sludge cake into a powder of high consistency; it
must have a high degree of consistency to achieve steady and complete combus-
tion. Mounted to the side of the HGS mill is the blower. The blower provides
the pneumatic lift to propel the ground powder up through the sludge burner
supply tubes (14). The suspension burners are located at the end of the tubes,
approximately one-third of the way up in the radiation shaft. The sludge powder
fuel, or SDF as it was previously characterized, is blown in through two hori-
zontal suspension burners, igniting instantaneously and burning extremely well.
The sludge is not fired together with the refuse; rather, each is fired separ-
ately. Only the flue gas stream coincides with the two processes. This is
critical to maintaining complete burnout.
3. Air Pollution Control:
The flue gases pass through an electrostatic precipitator (19) for parti-
culate removal, prior to entering the gas scrubbing building, via a fan (20).
There are two major components in the gas scrubbing building, the first being
the wet scrubbing system (21). This scrubbing system has two stages, and uses
two different scrubbing fluids. The first stage of the scrubber removes the
HC1 and HF trace gases, with an acid solution as is evidenced by negative pH;
this is done with a recirculating loop of liquid containing calcium hydroxide,
or Ca(OH)2.
The second stage works with an alkaline solution of a positive pH to scrub
out the S02> This is accomplished by the addition of sodium hydroxide, or NaOH.
-------
181
A portion of both scrubbing fluids is withdrawn for neutralization with lime and
subsequent solids separation. The solids thus extracted, mostly salts, are trans-
ported to a special landfill while the liquid is returned to the nearby sewage
treatment plant. This flue gas scrubbing system was originally developed by
Peabody.
The second major component in the gas purification building is the reheat
system. It works with a fan that draws in ambient air and with an air heater-
Some steam is taken out of the plant to heat the ambient air. The hot air is
then blended with the moist gases that are coming out of the scrubbers. As a
result, ..it can be said that, under most meteorological conditions, there will be
no visible plume from the plant. This system eliminates the plume problem often
associated with wet scrubber use, and prevents condensation problems in the stack.
In future plants, regenerative heat-exchangers made of glass tubes will be used
to eliminate the loss of energy associated with steam heating.
APC TESTING:
The Krefeld C-RPP is presently undergoing modifications and expansion and
several corrections were made in the scrubber part of its APC system. As a
result, APC testing is incomplete and a cohesive data base has not been estab-
lished yet.
However, the Kiel RPP in Northern Germany was the first plant to start up
with a new APC system which also features the combination of electrostatic
precipitators with wet scrubbers. There is no reason to believe that the
Krefeld system would not perform equally well. In fact, performance of the
Krefeld system in its final form is expected to surpass the Kiel results, especi-
ally with regard'to SO^ removal because rather than one, two scrubbing fluids
will be used, one of which has a particular affinity for sulfur.
Table 7 shows the results of APC testing at the Kiel RPP (see Reference
6). It is conceivable, however, that the Krefeld plant may deviate from Kiel
in two respects due to its assigned task to fire sludge in addition to refuse.
Particulate loadings into the precipitators are bound to increase. Also,
there may be an upswing in the collection of metals either as oxides in the
flyash, or as salts in the scrubber washing fluids.
Table 8 shows the concentrations of selected pollutants as they are re-
moved by the scrubbing fluid. Success with the treatment of the resulting
liquid effluents prior to their dumping into the municipal sewer is evidenced
by the values presented in the middle column of this table.
DOE GRANT FOR RESEARCH AT KREFELD C-RPP:
Recognizing the limited data base presently available on the emission from
C-RPP's employing the DD-SF method, and being keenly aware of the need to pro-
vide a complete and well documented data base before any large scale applica-
tions of this technology can be accomplished in the U.S., the US-DOE granted
a research program in October, 1978 with the following technical objectives
(see Reference 7):
- determine the minimum net energy usage requirements of the VKW
codisposal process;
- prepare complete material and energy balances for the process in
accordance with the system boundary limits described later herein;
- verify applicability of process to varying geography and varying
types of waste in respect to impact on economic viability and energy
requirements;
- evaluate environmental considerations related to acceptance and
commercialization of the process; and,
-------
182
- identify and address institutional barriers related to the re-
quirement of cooperation between the public and private sector.
Of particular inter t will be the effect which the variation of refuse,
sludge and moisture residuals will have on the stability of power production
as determined by boiler output parameters. More specifically, existing monitor-
ing instrumentation will be augmented to generate sufficient data to provide:
- typical thermal and mass balances for refuse firing;
- typical thermal and mass balances for refuse and sludge firing;
- gross and net energy production, thermal and electrical; and,
- quality of energy production as shown by typical 24-hour, 7-day and
monthly profiles for steam and electrical outputs.
A specific data collection program will be developed to provide a complete
reading of those 1'actors pertinent to the processes which impact the environ-
mental acceptance of the system, and/or its ultimate commercialization. The
testing will include data collection of all the gaseous and liquid effluents
and solid residues, resulting from the combined firing of solid waste and sewage
sludge for all operating conditions proposed for the system performance test.
More specifically, a combination of grab sampling, wet chemistry analysis and
on-line monitoring will be utilized to provide a complete data base which will
include:
- simultaneous measurements of particulates HC1, HF, SC^, and CO be-
fore the electrostatic precipitator, after the electrostatic pre-
cipitator, and after scrubbers;
- simultaneous measurement of water quality in the scrubber effluent
and the water treatment systems, plus in the quench tank effluent;
- ambient air quality at some point down wind (if this can be done
despite the closeness of other industry); and,
- micro-pollutant analysis, especially of heavy metals, with samples
of raw garbage from feed chutes, sludge coming from the HGS mill,
flyash and bottom ash respectively, boiler tube deposits, ash quench
water, scrubber water, and stack effluents.
Critical importance will be attached to the determination of the fate of the
heavy metals because of the concern expressed in many sectors of the United
States environmental field with regard to alternative approaches to sludge
disposal. Krefeld is most suitable for the pursuit of this aspect, because of
the presence of significant amounts of sludge derived from industrial waste
waters.
The test program will provide a preliminary assessment of the environmental
considerations of the DD-SF codisposal process. Measurement methods and test
equipment will be responsive to the requirements of the Reference Test Methods
promulgated by the United States Environmental Protection Agency.
CONCLUSION;
The urgency to identify alternative approaches to dumping and landfilling
carries with it the need to identify alternatives that reflect a more prudent
use of energy, in a more cost-effective manner. The European experience, through
technology transfer, can provide such an alternative at acceptable risks.
The codisposal of sewage sludge with solid waste is now being successfully
practiced in Europe. The European technology for codisposal can be considered
proven and operational both in terms of significant scale and longevity of
operations. Attempts in the United States to develop comparable systems have
-------
, , 183
not Deen successful, to date. Among competing technologies, the DD-SF method
of thermal sludge processing as practiced in Krefeld has proven superior. Also,
the European experience has shown codisposal and its attendant SDF production to
be beneficial in both energy and economic terms. By utilizing solid waste as an
alternative fuel in the place of oil and gas, the operation of codisposal facili-
ties has resulted in a meaningful reduction in energy consumption which benefits
both the local government and the national economy. This holds especially true
for the very large plants serving metropolitan areas.
Based on this experience, many communities in the United States are now
investigating the establishment of codisposal facilities. They are being
hampered in this effort, however. In the absence of any prolonged testing, no
extensive data base exists today on two key aspects: energy performance and
efficiency and environmental impact, particularly of heavy metals emissions.
The availability and use of such data is essential to project development in
the United States.
The DOE program, it is hoped, will provide the long range answers to most,
or perhaps even all of these questions. It is regrettable that this program
will not yield tangible results in time to affect the implementation of compliance
programs presently being planned by a number of large Eastern municipalities
which are traditionally being involved with ocean dumping.
It would be prudent for the U.S. EPA to consider permit extensions for
municipalities which are seriously committed to finding long term solutions to
the sludge problem, such as C-RPP's which by their very nature may require a
3 to 4 year planning and construction cycle.
References:
1. "A Review of Techniques for Incineration of Sewage Sludge with Solid
Wastes" by Roy F. Weston, Inc., West Chester, December 1976.
2. "Refuse Power Plant Technology - State of the Art Review" by Klaus S.
Feindler, Seminar of the Energy Bureau Inc., Plaza Hotel, NY, December 16,
1976.
3. "Stand der Abfallverbrennung in der Bundesrepublik Deutschland" by Lothar
Barniske and Horst Vosskoehler, Muell und Abfall, 10. Jahrgang, 1978,
Heft 5, Erich Schmidt Verlag.
4. "Gemeinsame Verbrennung von Muell und Klaerschlamm" by Hans Kroehl,
2nd Refuse Power Technology Seminar, Moenchen-Gladbach, June 7, 1978.
5. "The Incineration of Sewage Sludge with Domestic Refuse on a Continuous
Burning Grate" by C.S.H. Munro and T.J.K. Rolfe, I. Chem. E. Symposium
Series, No. 41.
6. "Muellverbrennungsanlage Kiel: Betriebsablauf und Betriebserfahrungen unter
besonderer Beruecksichtigung der Rauchgaswaschanlage" by Helmut Grimm,
3rd Refuse Power Technology Seminar, Duesseldorf, November 14, 1978.
7. "Research Program for the Evaluation of the Codisposal of Sewage Sludge
with Solid Waste," proposal by Grumman Ecosystems Corporation to the US-
DOE program announcement EM-78-D-01-5136 Research and Development for
Combined Solid/Liquid Waste Energy Recovery Systems, August 10, 1978T
-------
184
Figure 1: Krefeld Codisposal and Refuse Power Plant
with Recreation Area and Sewage Treatment
Plant
-------
185
Figure 1A: Krefeld Codisposal Plant: Plot Plan
-------
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-------
Figure 2 : Sectional View of Krefeld.West Germany
Codisposal and Refuse Power Plant
r
2.
3.
4.
6.
6.
7.
8.
9.
10.
11.
Tipping Floor
Refute Storage Pit
Refuse Charging Crane
Feed Hopper
Ram Feeder
Roller Grate System for Refuse Incineration
Ash Storage Pit
Aih Removal Crane
High Performance Boiler
Centrifuges for Dewatering Sludge
Sludge Cake Storage Containers
12. Sludge Drying and Grinding Mill
13. Flue Gas Recirculation Duct
Sludge Burners
Central Control Room
Turbogenerators
Machinery Cram
Feedwater Storage Tanks
Electrostatic Precipitators
Exhaust Fan
Flue Gas Scrubbers
Exhaust Stack
-------
Table #1: European and Asian C-RPP's of the DH-SF Type page ] <$ 2
Plant
Name
Startup
Year
Design Processing Capacities
Processing Lines
stph
Refuse
STPD
Sludge
WSTPD
DSTPD
Steam Conditions
Temperature Pressure
°F psig
Essen-Karnap
Solothurn
Krefeld
Furstenfeldbruck
Ingolstadt
Barnberg
Kyoto
Bielefeld
Munich III
1961/65
1973
1975/80
1975
1977/81
1977/81
1979
1981
1981
5
2
2
1
1
2
1
2
1
3
3
2
X
X
X
X
X
X
X
X
X
X
X
X
22.0
11.0
13.2
19.4
6.6
8.3
8.3
6.6
6.6
16.5
17.6
24.2
1,500
528
1,100
158
594
475
1,188
1,270
1,162
1,800
( Planning
510
(@26%TS)
52
(@45.7%TS)
159
(§25%TS)
150
(@40%TS)
( Planning
555
(@45%TS)
634
(@25%TS)
1,035
Stage )
133
24
40
74
Stage)
250
475
950
707
707
Sat.
(Retrofit
Sat.
770
752
752
1,421
551
363
341
Planned )
370
1,088
580
580
-------
Table #1 (cont.
Plant
Energy Output
APC System
2 of 2
Technology Origin
Name
Electricity/Steam
MW
Components
Essen-Karnap
Solothurn
Krefeld
Furstenfeldbruck
Ingolstadt
Bamberg
Kyoto
Bielefeld
Munich III
5 x 50 = 250
1 x 8 = 8
2 x 1.4 + 1 x 4.25 = 7.1
or 1 x 11.5 = 11.5
and/or 200 x 106 Btu/hr
Housekeeping
and Process Needs
Housekeeping
and Process Needs
Housekeeping
and Process Needs
1x4 = 4
1 x 30 r 30
1 x 23 = 23
or 1 x 26 r 26
ESP's
ESP's
ESP's + M.S.
- Wet Scrubbers
ESP + Wet
Scrubber
ESP's + Wet
Scrubbers
ESP's + Wet
Scrubbers
ESP's
ESP's + Wet
Scrubbers
ESP's +
Scrubbers
Deutsche Babcock
Von Roll
VKW
Keller Peukert/VKW
Widmer + Ernst
Keller Peukert/VKW
Kawasaki/VKW
Widmer + Ernst
VKW/Martin
VD
to
-------
Table 2 :
SOURCES OF AIR POLLUTION: USA vs. FRG 1n 1973
POLLUTANT
Carbon Monoxide, CO
Sulfur Oxides, SOx
Nitrogen Oxides, NOj
Hydrocarbons, HC
Hydrogen Chlorides, HC1
Fluorides, HF
Offensive Odors
Particulates
TOTALS
USA EMISSIONS (1
TOTAL IN MT/Y
91,500,000
32.300,000
20,900,000
28,400,000
N.A.
N.A.
N.A.
19.900,000
> 193.000.000
INCINERATORS
MT/Y
254,000
10.900
14.500
10,900
N.A.
N.A.
N.A.
104,300
> 394, 600
% OF TOTAL
0.278
0.034
0.069
0.038
N.A.
N.A.
N.A.
0.524
0.204
FRG EMISSIONS (2) __,
TOTAL IN MT/Y
8,000,000
4.000.000
2.000,000
2.000.000
> 17.000(4)
40,000
N.A.
4.000,000
> 20,057,000
INCINERATORS
MT/Y
1,000
12,000
5.000
2.000
8.000
50
None
2,000
30.050
% OF TOTAL
0.013
0.300
0.250
0.100
<47.059
0.125
N.A.
0.050
0.150
EMISSION RATIOS USA/FRG (3)
TOTALS
11.44
8.08
10.45
14.20
N.A.
N.A.
N.A.
4.98
9.62
INCINERATORS
254.0
0.9
2.9
5.5
N.A.
N.A.
N.A.
52.2
13.1
MAJOR CONTRIBUTORS
Transportation
Power Plants,
Diesel -powered
transportation
Transportation,
Power Plants,
Steel Industry
Transportation
Miscellaneous
Process Industry,
Power Plants,
Incinerators
Process Industry
Various Industries,
Landfills
Power Plants,
Various Industries
NOTES: (1) Source: U. S. Environmental Protection Agency, National Emissions Data Center
(2) Source: "Wohin mit den Abfallen? Umweltschutz durch Mullverbrennung" ("Environmental Protection Through Refuse Incineration")
(3) For comparison in 1973 the population ratio was USA/FRG = 210.4/62.0 = 3.39
(4) Power plants account for another 8,500 MT/Y in the FRG. The process industry is strongly suspected as a major contributor, but
the amounts involved are difficult to estimate.
-------
Table #3 : Average Gaseous Emissions from European RPP's and C-RPP's
Page 1 of 3
Plant
Units Tested
Test Date:
Participates
(mg/Nrrr)
so2 + so3
(mg/Nm3)
** 3
(mg/NmJ)
HC1 -
(mg/NnT)
NO + MX,
(mg/Nm3)
Test
Point
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Paris
Issy
1 - 4
Feb. 77
N.M.(2)
46(2)
N.A.UJ
N.M.
132
N.A.
N.M.
N.M.
N.A.
N.M.
1,416
N.A.
N.M.
135
N.A.
Paris
Ivry
U2
Jul. 77
N.M.
117
N.A.
N.M.
132
N.A.
N.M.
N.M.
N.A.
N.M.
1,050
N.A.
N.M.
171
N.A.
Zurich
Hagenholz
1;2
(?)
N.M.
72
N.A.
N.M.
219
N.A.
N.M.
N.M.
N.A.
N.M.
531
N.A.
N.M.
N.M.
N.A.
Zurich
Hagenholz
3
73
N.M.
42
N.A.
N.M.
220
N.A.
N.M.
11
N.A.
N.M.
840
N.A.
N.M.
N.M.
N.A.
Uppsala
1 - 4
Apr. 74
731
21
N.A.
N.M.
190
N.A.
N.M.
N.M.
N.A.
N.M.
78
N.A.
N.M.
N.M.
N.A.
Data Source
Battelle
RPA
Battelle
Battelle
Battelle
-------
Table # 3 (cont.)
Plant
Rosenheim
Rosenheim
Dusseldorf Dusseldorf
Data Source
VGB
VGB
Operator
Operator
Page 2 of 3
Dusseldorf
Units Tested
Test Date
Participates
(mg/Nrn )
so2 + so3
(mg/Nm3)
HF
(mg/Nnr)
HC1 -,
( mg/Nm )
NO + NO-
(mg/Nm3)
Test
Point
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
1
Oct. 65
6,900
77
N.A.
N.M.
2,486
N.A.
N.M.
N.M.
N.A.
N.M.
712
N.A.
N.M.
N.M.
N.A.
1
May 68
6,400
71
N.A.
N.M.
1,259
N.A.
N.M.
5
N.A.
N.M.
576
N.A.
N.M.
N.M.
N.A.
1 - 4
67/69
12,087
39
N.A.
N.M.
918
N.A.
N.M.
N.M.
N.A.
N.M.
778
N.A.
N.M.
N.M.
N.A.
1 - 4
70
N.M.
N.M.
N.A.
N.M.
855
N.A.
N.M.
N.M.
N.A.
N.M.
970
N.A.
N.M.
N.M.
N.A.
1 - 4
71
N.M.
N.M.
N.A.
N.M.
738
N.A.
N.M.
N.M.
N.A.
N.M.
948
N.A.
N.M.
N.M.
N.A.
Operator
-------
Plant
Units Tested
Test Date
Particulates
(mg/Nm )
so2 + so3
(mg/Nm3)
HF
(mg/Nra0)
HC1 _
(mg/Nm )
NO + NO-
3
(sng/Nm )
Test
Point
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Boiler
ESP
Scrubber
Dusseldorf
1 - 5
73 - 77
N.M.
N.M.
N.A.
N.M.
505
N.A,
N.M.
9
N.A.
N.M.
1,000
N.A.
N.M.
9
N.A.
Stockholm
Hogdalen
1;2
June 72
2,700
216
N.A.
N.M.
250
N.A.
N.M.
5
N.A.
N.M.
629/777
N.A.
N.M.
125
N.A.
Stockholm
HCgdalen
(?)
Nov. 74
N.M.
N.M.
N.A.
N.M.
1,987
N.A.
N.M.
0.3
N.A.
N.M.
1,266
N.A.
N.M.
N.M.
N.A.
Krefeld
V,2
76
N.M.
N.M.
N.M.
N.M.
450R
N.A.
N.M.
N.M.
N.A.
N.M.,.,,
0,257 R(3)l
(1,183 R+S )
N.M.
216 R
N.A.
Page 3 of 3
Kiel
v,2
76
8,330
184
19
N.M.
550
250
N.M.
9.3
.4
N.M.
1,170
24
N.M.
N.M.
N.A.
Data Source
Battelle
Avloppsverken R. Nilsson
VKW
Operator
Notes: 1) Data is not always correct to the same reference conditions.
2) N.M. denotes parameter was not measured, N.A. means "not applicable," i.e. allowable emissions were not
specified by licensed board,and therefore, no specific removal equipment was provided.
3) R denotes "refuse firing only;" R+S denotes "refuse and sludge firing."
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Table #4:
REFUSE POWER PLANTS: EMISSION STANDARDS
WEST GERMANY vs. U.S.A.
PARAMETER
PARTICULATES
HC1
so2
HF
CO
OPACITY
WIN. TEMPERATURE
UNITS
mg/Nm
mg/Nra
mg/Nm
mg/Nm
mg/Nm
Ringelmann No.
°C @ 0.3 sec
ALLOWABLES
W. GERMANY (la)(lb)
100
100
100^
5
1,000
1
800
U.S. A. (3)
180 (5)
—
—
—
—
—
—
MASS.(4)
115 (6)
—
—
—
—
1
—
NOTES: (la) Source: TA Luft 1974 (Technische Anleitung zur Reinhaltung der Luft)
(Ib) Reference Conditions: 0° C, 1030 mbar, 11% Vol. 0, moist gases
(2) Krefeld C-RPP and Hamburg RPP, not general requirement yet.
(3) Source: EPA Regulations on Standards of Performance for New Stationary
Sources, as amended, 1975; Subpart E - Standards of Performance for
Incinerators.
(4) Source: Massachusetts Air Pollution Control Regulations, 1972 Section 2.5.3
(5) Corresponds to 0.08 gr/dscf
(6) Corresponds to 0.05 gr/dscf
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TABLE 5 May 31, 1979 198
Sheet 1 of 2
Mandatory Air Pollution Control Criteria for
West German RPP's and C-RPP's (1) (2) (3)
Translated and Edited by Klaus S. Feindler*
1. The refuse storage pit must be kept below atmospheric pressure; the
air which is drawn off shall be fed to the furnace. In the case of
facilities intended for continuous operation, if the furnace is
temporarily shut down, (for example, as the result of equipment mal-
function) , then the drawn-off air must be vented via the stack.
2. If liquid wastes are to be burned in addition to solid wastes, then
these liquid wastes must be stored in closed containers. Transfer
points with openings need to be equipped with suction devices such
that the drawn-off air can be fed into the furnace.
3. The facilities must be equipped with a supplemental firing system.
4. All facilities must be connected to a stack.
5. The facilities must provide an afterburning chamber which opens into
the combustion chamber, or is located downwind from it, so that waste
gases can be retained in it for at least 0.3 seconds at a minimum
temperature of 800° C. (1,472° F) and a minimum 0- concentration of
6% by volume. This temperature is to be monitored by continuously
recording instrumentation. The facilities must be laid out in such
a manner that waste charging is only possible when this minimum tempera-
ture has been reached. A supplemental burner needs to be installed in
the afterburning chamber which turns on automatically as soon as the
temperature drops below the allowable minimum. Such afterburning
needs to take place even if the facility is not in operation and the
air drawn off the refuse storage pit is vented through the afterburning
chamber.
6. The facilities shall be operated in such a manner that the highest
degree of burnout possible is guaranteed for the waste gases and any
fermentable components entrained in them.
7- Particulate emissions in the wet waste gases may not exceed 100 mg/m3
corrected for an 02 content of 11% by volume and referred to standard
conditions of temperature and pressure (0° C and 1,013 mbar or 32° F
and 14.69 psia)
8. The opacity in the waste gas plume shall be less than the value of
number 1 on the Ringelrnann scale.
9- The criteria of paragraphs 6 and 7 shall be maintained even during
periods of soot blowing from the boilers.
^Formerly Technical Director with Grumman Ecosystems Corporation and
presently a Resource Recovery Specialist with Quantum Associates.
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199
Sheet 2 of 2
10. Anorganic emissions in the moist waste gases may not exceed the fol-
lowing values:
Chlorine compounds (expressed as C2~) = 100 mg/m3
Fluorine compounds (expressed as F~) =5 mg/m3
These values are to be corrected for an 0^ content of 11% by volume
and referred to standard conditions of temperature and pressure.
11. Carbon monoxide concentrations in the moist waste gases may not
exceed 1,000 mg/m3 corrected for an 02 content of 11% by volume and
referred to standard conditions of temperature and pressure.
12. Instrumentation is to be provided for the continuous recording of
the concentrations of particulates, anorganic chlorine compounds and
fluorine compounds in the effluent waste gases.
13. Polychlorinated biphenyls (PCB's), or materials containing PCB's
can only be burned in facilities especially equipped for such furnaces:
i.e. furnaces which can maintain a minimum temperature of 1,200° C/
(2,192° F).
14. Organic compounds (essentially unburnt hydrocarbons) as part of
effluent vapors or gases are classified according to their chemical
structure in 3 classes which range in their allowable emissions from
20 to 300 mg/m3. In case several classes are present, the sum of
all organic emissions shall not exceed 300 mg/m3.
Notes: (1) Source: TA Luft 74 (Technische Anleitung zur Reinhaltung
der Luft, or Technical Guidelines for the Protection of Air
Purity) and GMBL 1974 of August 28, 1974, pages 426 and 452.
(2) Covers class 2 facilities which are to burn, completely or
in part, predominantly wastes from households, or similar
materials, with a mass flow capacity in excess of 0.75
mtph (0.83 stph).
(3) The burning of "other wastes" (i.e. industrial and hazardous
wastes) is covered elsewhere in the guidelines; they are
omitted here for reasons of brevity.
-------
Table 6 : Classification of Wastes
Processed by the puesseldorf HPP
200
WASTE CLASSIFICATION
1. Residential Refuse (Burned as Received)
la. Collection by Host City
Ib. Collection by Outside Municipalities
Ic. Combined Collections
2. Industrial & Commercial Refuse
(Burned as Received)
3. 'Bulky Wastes
(Burned after Shredding and Mixing)
4. Yardwaste & Sweepings
(Burned as Received)
5. Dirt with Oil Contamination
(Burned as Received)
6. Automobile Tires
(Burned after Shredding and Mixing)
TOTAL Z 1-6
ANNUAL THROUGHPUT
MT
167,472
32.530
200,002
66,368
19,624
9,210
2,213
767
298,184
I
56.2
10.9
6TT
22.3
6.6
3.1
0.7
0.3
100.0
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201
Table 7i
REFUSE POWER PLANTS ,. *
PERFORMANCE OF ESP AND WET SCRUBBER AT MVA KIEI/1;
PARAMETER
INFLUENT TO ESP
INFLUENT TO SCRUBBER
EFFLUENT FROM SCRUBBER
REMOVAL EFFICIENCY
- AVERAGE^2'
- MINIMUM
- MAXIMUM
NUMBER OF MEASUREMENTS
UNIT
mg/Nm3
mg/Nm3
mg/Nm3
%
%
%
HC1<2>
-
1,170
2**
98
96
99
2k
H,(2)
-
9.3
0>
96.0
9^.0
98.0
2U.O
so2
-
550
250
55
U6
59
20
PARTICULARS^3'
5,200 - 13,000
89-26?
15 - 26
85 - 90
-
-
U
NOTESi (1) Sourcet Dlpl. Ing. Helmut Grimm of MVA Kiel
02 by volume
(2) Corrected to
(3) System was intentionally overloaded by
changing from design rate of 5.5 stph to
test rate of 8.35 stph; i.e. the system
carried a 51 % overload by refuse weight.
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202
Table 8 :
REFUSE POWER PLANTS: SCRUBBER WATER POLLUTANTS AT MVA KIEL
0)
PARAMETER
UNITS
RECIRCULATION
LOOP
BLEED2 ALLOWABLES
LOOP (HUSMANN)
CHLORIDES
i
i
CHROMIUM (TOTAL)
COPPER
I
MERCURY
1
NICKEL
1
SULFATES
TIN
ZINC
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
\ mg/1
mg/1
[6,000]
[7,000]
0.20
1.15
0.30
0.57
145.
1.80
33.54
2,000
0.05
0.15
0.20
0.20
233.
i
1.00
2.50
4.00
3.00
-
5.00
400.
i
5.00
-i
NOTES:
(1) Source: Dipl. Ing. Grimm of MVA Kiel
(2) After neutralization, and after sludge settling
(3) Arbeitsblatt #90, December 1970:
"Hinweise fur das Einleiten von Abwasser aus gewerblichen u.
industriellen Betrieben in eine Offentliche Abwasseranlage"
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203
APPENDIX E. LIST OF ABBREVIATIONS
-------
204
LIST OF ABBREVIATIONS
APC Air pollution control
BTU British thermal unit
CCCSD Central Contra Costa Sanitary District
CCSL Carlton County Sanitary Landfill
CDM Camp, Dresser and McKee, Inc.
DDCSL Duluth Disposal Company Sanitary Landfill
DOE U.S. Department of Energy
ENR Engineering News Record
EPA U.S. Environmental Protection Agency
FBF Fluidized-bed furnace
FOB Free on board
GO General obligation
MC Metropolitan Commission (Minneapolis-St. Paul)
MGD Million gallons per day
MHF Multiple-hearth furnace
MSS Municipal sewage sludge
MSW Municipal solid waste
MWCC Metropolitan Waste Control Commission (Minneapolis-St. Paul)
NCRR National Center for Resource Recovery
0 & M Operating and maintenance
PL 95-217 Clean Water Act Amendments of 1977
RCRA Resource Conservation and Recovery Act of 1976
RDF Refuse-derived fuel
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206
SWPF Solid waste processing facility
TCMA Twin Cities Metropolitan Area
TPD Tons per day
USDA U.S. Department of Agriculture
WLSSD Western Lake Superior Sanitary District
WWTP Waste water treatment plant
ya 1825
SW-184C
OU.S. GOVERNMENT PRINTING OFFICE: 1980 311-132/4 1-3
-------
EPA REGIONS
U.S. EPA, Region 1
Solid Waste Program
John F. Kennedy Bldg.
Boston, MA 02203
617-223-5775
U.S. EPA, Region 2
Solid Waste Section
26 Federal Plaza
New York, NY 10007
212-264-0503
U.S. EPA, Region 3
Solid Waste Program
6th and Walnut Sts.
Philadelphia, PA 19106
215-597-0980
U.S. EPA, Region 4
Solid Waste Program
345 Courtland St., N.E.
Altanta, GA 30308
404-881-3016
U.S. EPA, Region 5
Solid Waste Program
230 South Dearborn St.
Chicago, IL 60604
312-353-2197
U.S. EPA, Region 6
Solid Waste Section
1201 Elm St.
Dallas, TX 75270
214-767-2645
U.S. EPA, Region 7
Solid Waste Section
324-E11thSt.
Kansas City, MO 64108
816-374-3307
U.S. EPA, Region 8
Solid Waste Section
1860 Lincoln St.
Denver, CO 80295
303-837-2221
U.S. EPA, Region 9
Solid Waste Program
215 Fremont St.
San Francisco, CA 94105
415-556-4606
U.S. EPA, Region 10
Solid Waste Program
1200 6th Ave.
Seattle, WA 98101
206-442-1260
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