EPA
SW-73-0
RESOURCE RECOVERY PROCESSES FOR MIXED
MUNICIPAL SOLID WASTES
PART I—TECHNICAL REVIEW AND ECONOMIC ANALYSIS
This final report (MRI~Project No, 3634-D) was prepared by
WILLIAM E. FRANKLIN, DAVID BENDERSKY, LARRY J. SHANNON, AND WILLIAM R. PARK
for the Couneil on Environmental Quality and is reprinted by the
Office of Solid Waste Management Programs
U.S. ENVIRONMENTAL PROTECTION AGENCY
1973
-------
Mention of commercial products does not
imply endorsement by the U.S. Government
-------
PREFACE
This report was prepared for the President's Council on Environ-
mental Quality, under MRI Project Nos. 3523-D and 3634-D. The purpose of
these projects was to review and assess the technology for recovery of re-
sources from mixed municipal solid wastes. The results are presented in two
parts. Part I consists of a review and analysis of the technical and eco-
nomic aspects of resource recovery processes. Part II is a compilation of
basic data on 40 current and emerging resource recovery processes.
The project officer for the Council on Environmental Quality was
Mr. Eric Zausner. Valuable guidance and information was furnished by
Messrs. Arsen Darnay and Stephen Levy of EPA's Office of Solid Waste Manage-
ment Programs, Resource Recovery Division. Furthermore, the cooperation of
the organizations that furnished information on their resource recovery
processes is gratefully acknowledged.
The project leader for the MRI team was Mr. William E. Franklin,
Senior Environmental Economist. The technical analyses were carried out by
Mr. David Bendersky, Principal Engineer, and Dr. Larry J. Shannon, Principal
Chemical Engineer. The economic analyses were carried out by Mr. Franklin
and Mr. William R. Park, Principal Economist. Mr. Gary Nuss, Assistant
Director of the Economics and Management Science Division, administered the
project.
Approved for:
MIDWEST RESEARCH INSTITUTE
John McKelvey, Vice President
Economics and Management Science
iii
-------
-------
TABLE OF CONTENTS
Pagt
Summary 1
Chapter I - Introduction 5
Chapter II - Technical Review of Resource Recovery Processes 6
2.0 General Classification 6
2.1 Energy Recovery Processes ..... 6
2.2 Materials Recovery Processes 10
2.3 Pyrolysis Processes 11
2.4 Composting 15
2.5 Chemical Systems 16
Chapter III - Economics of Basic Resource Recovery Processes 17
3.0 Introduction 17
3.1 Basic Conditions for the Detailed Economic Analysis 19
3.2 Economics of Basic Systems 24
3.3 Relative Economics of the Systems 55
3.4 Resource Marketability and Its Effect on Economic Rankings . . 59
3.5 Municipal Vs Private Ownership 64
3.6 Resource Supply Contrasted with Plant Economics of Scale. ... 66
-------
-------
SUMMARY
This survey and analysis of the present status of technology for
resource recovery from mixed municipal waste shows that the national goal
expressed in the Resource Recovery Act of 1970 has been perceived by the
government and industry as one worthy of substantial commitment. A signifi-
cant response has already been seen in the form of the development of numer-
ous resource recovery processes. On the other hand, the development has
been largely unfocused and uneven because the specific technological needs
of resource recovery are not yet well defined. We appear, at this point, to
have a rather impressive shopping list of technology to choose from, but do
not know which system concepts to buy or even whether to buy at all. Part
of the problem is that technological development has been focused on
processing a "new" raw material stream--mixed municipal waste—but the re-
sulting product output does not necessarily result in something for which
there is a ready market.
Technical Summary; Only two methods are currently fully developed
and practiced for the recovery of resources from mixed municipal waste--
heat recovery from incinerators and composting. Heat recovery from incin-
erators has been practiced in Europe and Japan for some time. Recently,
heat recovery incinerators of European design have been introduced into the
U.S. and Canada. Although heat recovery from incinerators has been practiced
for some time, there are still some significant technical problems with these
systems such as erosion and corrosion of the boilers and reliable deliver-
ability of the product. The technology of composting is well established.
There are several composting techniques, the most successful being the
Fairfield-Hardy and the Varro systems. Poor marketability of the finished
product has been a factor in a rather unimpressive history of composting in
the U.S.A.
There has been a marked increase in the development of new tech-
nology for resource recovery from municipal waste during the last few years.
Included in this emerging technology are: (1) energy recovery processes,
(2) materials recovery processes, (3) pyrolysis processes, and (4) chemical
conversion processes.
The emerging energy recovery technology includes fuel recovery
processes, steam generation processes, and electrical power generation
processes. Energy recovery is applicable only to the organic fraction of
wastes, but many of the energy recovery processes also recover some of the
inorganics (metals and glass). Two of the promising fuel recovery systems
are the Horner-Shifrin and the A. M. Kinney processes. The Horner-Shifrin
process involves dry shredding of the refuse and using it as a supplementary
-------
fuel in existing power plant furnaces. A. M. Kinney has a design to wet
pulp waste organics for use as a supplementary industrial or power plant
fuel.
Two new steam generation systems, designed by the American Ther-
mogen Company and Torrax Systems, Inc., involve the recovery of heat from
the combustion of refuse in special furnaces. The novel aspect of these
systems is the use of high-temperature furnaces which require no presepara-
tion or preparation of the waste, and which melts all of the residue to a
lava-like frit.
Another new energy recovery system, called the CPU-400, is de-
signed to burn shredded municipal waste in a high pressure fluid-bed corn-
buster and uses the hot gases to drive a gas turbine-electric generator.
This system is presently in the pilot plant development stage.
The materials recovery processes are designed to remove paper,
ferrous and nonferrous metals, and glass from the refuse. In most
processes all four materials are recovered. Both wet and dry processes
have been devised to separate the paper from mixed waste. Techniques to
remove the metals both from the mixed waste and from incinerator residues
are being developed. Most of the ferrous metal separation techniques are
based upon magnetic separation—a well-developed technology. The glass is
separated by air classifiers (separation by density) and color sorting
using optical devices or by flotation techniques. The materials recovered
in these systems are generally of a quality that subsequent refinement or
additional upgrading may be necessary to obtain fully marketable products.
The most developed materials recovery systems are the Black-Clawson Fibre-
claim system, and an incinerator residue recovery system developed by the
U.S. Bureau of Mines.
A number of organizations are in the process of developing
pyrolysis processes that recover synthetic fuel oil, gas or other poten-
tially valuable materials from municipal wastes. These pyrolysis systems
involve the thermal degradation of the waste in a controlled amount of
oxygen. Some of the products that have been obtained from municipal waste
by pyrolysis systems are oils, gas, tar, acetone, and char. Pyrolysis is
an attractive method for waste resource recovery because of the basic
flexibility of the technique; changes in operating conditions can be made
to vary the nature of the recovered products.
The Garrett Research and Development Company has developed a
pyrolysis process that recovers synthetic fuel oil from refuse (glass and
ferrous metal are also recovered). The Garrett system appears attractive
because of the reported high yield of low sulfur oil and substitutability
-------
for low-grade fuel oil. However, it has not yet been determined whether
the recovered oil will be readily usable as a substitute for commercial
fuel oils. Union Carbide has a high-temperature pyrolysis process from
which the combustible off-gases can be cleaned for use as a fuel gas for
utility furnaces. The adaptability of the synthetic gas to commercial
furnace fuel systems has not been fully determined yet. Monsanto has a
pyrolysis system that has been tested to a much greater extent than any
of the other pyrolysis systems. Furthermore, their pyrolysis unit is
based upon extensive rotary kiln design experience. Both facets speak well
for probable success of the Monsanto pyrolysis system. The primary
pyrolysis unit (fluid-bed type) proposed by the Hercules Company is feasi-
ble, but unproven; their back-up unit is a well-developed furnace for pro-
ducing wood charcoal. Battelle Northwest and West Virginia University have
also been working on the development of pyrolysis processes for mixed
municipal wastes.
There are a variety of chemical conversion processes (anaerobic
digestion, acid hydrolysis, wet oxidation, hydrogennation, and photo-
degradation) which have been conceived for mixed municipal waste, resulting
in such products as proteins, methane, glucose sugar, oils, alcohol, yeasts,
and other organic chemicals. Since most of these processes utilize only
the cellulose portion of the waste, separation and pretreatment of the
waste is necessary. Most of these processes are in early stages of
development.
Economic Summary; The most obvious finding of our economic anal-
ysis is that resource recovery systems are not self-sustaining economic
operations under the conditions of the analysis used. They do not recover
revenue sufficient to offset total costs; all systems analyzed show a net
cost of operation. However, where incineration, remote landfill, or other
high-cost waste disposal is necessary, resource recovery offers an econom-
ically viable alternative. Most resource recovery systems show lower costs
than conventional incineration (without resource recovery); several have net
costs (for large capacity plants) low enough to compete with landfill, if the
recovered products can be sold at or above the assumed prices.
Under the conditions used in the generalized economic analysis, the
process ranking by lowest net cost is: (1) fuel recovery, (2) materials re-
covery, (3) pyrolysis, (4) composting, (5) steam generation with incinerator
residue recovery, (6) steam recovery, (7) incinerator residue recovery, and
(8) electrical energy generation. The' net operational costs (based on a 1,000
TPD plant) range from about $3.00/ton for fuel recovery systems to about $9.00/
ton for electrical energy generation.
-------
Most of the emerging systems for resource recovery utilize new
technology or at least unique combinations of existing industrial tech-
nology. Political jurisdictional units are often hesitant to experiment
with new or unproven technology since this represents a radical departure
from traditional waste management practices and introduces "high risk" of
taxpayer funds. This is true even though a system developer may guarantee
performance of a specific system. However, in order to introduce techni-
cally and economically viable disposal/resource.recovery systems waste
management jurisdictions will be required to adopt relatively sophisticated
technology and competitive marketing skills.
Most of the resource recovery systems examined are capital in-
tensive, i.e., a large capital investment is required for each system.
Therefore, the fixed costs of operation are quite high in relation to total
costs. These systems should be operated at or near capacity to minimize
unit costs and maximize salable product output. In addition, the systems
show economies of scale, so that the larger the system, the more attractive
the unit cost of operation.
Perhaps the most critical economic factor is marketability of the
output products. All of the resource recovery techniques produce products
that must compete with established commodities directly or indirectly in
the marketplace. The variables of most importance are: unit price (or
value), throughput quantity and the percent of input (or output) that is
salable. In turn, these variables are dependent upon the quality of the
recovered product and its applications or demand in the specific situation
in which it occurs.
In summary, waste processing for resource recovery requires so-
phisticated industrial technology and a large capital investment, and must
be operated within competitive industrial market conditions. Nonetheless,
resource recovery is a viable alternative to traditional waste disposal
practices and should be carefully assessed by any municipality or juris-
dictional unit faced with a waste disposal investment decision and/or high-
cost waste disposal.
-------
CHAPTER I
INTRODUCTION
The Council on Environmental Quality has as one of its responsi-
bilities the formulation of national policy in the area of resource recovery.
In the past, the conservation or reuse of materials in solid waste streams
has generally been a federal government concern and practiced in the U.S.
only during wartime, when raw materials were in short supply. However, the
vast and growing amounts of solid wastes generated daily, the present prob-
lems and costs of proper disposal of these wastes, and the increased interest
in useful recovery ("recycling"), and conservation of materials have created
an interest in systems designed to recover resources from municipal solid
wastes. As a result of the increased interest in resource recovery, tech-
niques for waste recycling have been developed or proposed during the last
several years. These systems range in development from the conceptual de-
sign stage through laboratory-scale units, pilot plants, demonstration plants,
and full-scale operating systems. While we appear to have numerous alter-
native systems for waste recycling, a comparative technical and economic as-
sessment needed to define the relative merits of the various techniques had
not been conducted.
The Council on Environmental Quality engaged Midwest Research
Institute to assist in the assessment of technology applicable to resource
recovery from mixed municipal solid wastes. Basic technical and economic
data were gathered and compiled on a total of 40 existing and emerging re-
source recovery systems. The information was gathered through questionnaires
sent to developers of each system, published and unpublished literature, per-
sonal communications, and selected site visits. The compilation of basic
data on these systems is contained in PART II--CATALOGUE OF PROCESSES.
An analysis was conducted of the technical and economic aspects
of resource recovery systems that are ready for demonstration or are com-
mercial plants. The results of these analyses are contained in PART I--
TECHNICAL REVIEW AND ECONOMIC ANALYSIS, herein.
-------
CHAPTER II
TECHNICAL REVIEW OF RESOURCE RECOVERY PROCESSES
2.0 General Classifications
The various resource recovery processes covered in this study* may
be classified into the following general categories:
1. Energy Recovery Processes; Processes that recover the energy
content of mixed municipal wastes, in the form of either steam, electricity,
or fuel.
2. Materials Recovery Processes; Processes which separate and
recover the basic materials from mixed municipal wastes, such as paper,
metals and glass.
3. Pyrolysis Processes; Processes that thermally decompose the
mixed municipal waste in controlled amounts of oxygen and produce products
such as oil, gas, tar, acetone and char.
4. Compost Processes; Processes which produce a humus material
from the organic portion of the mixed waste.
5. Chemical Conversion Processes; Processes which chemically
convert the waste into protein and other organic products.
2.1 Energy Recovery Processes
2.1.1 Heat recovery incinerators. European countries have pio-
neered in heat recovery from the incineration of municipal refuse. Heat re-
covery incinerators have been in operation for a number of years in France,
Germany, and Switzerland. Steam is produced and used for heating and/or for
the generation of electrical power. European engineers have led in the de-
velopment of the refuse-fired boiler plant utilizing waterwall furnaces.
Waterwalls are favored over refractory walls primarily because they permit
operation at temperatures considerably higher than with refractory walls,
thereby substantially increasing the efficiency and reducing the excess air
requirement.
The resource recovery processes included in this study represent a broad
spectrum of the present technology; however, not all individual pro-
cesses were included.
6
-------
Heat recovery incinerators have been introduced into U.S. waste
disposal operations in recent years (e.g., Norfolk Naval Base, 1967, Braintree,
Massachusetts, and Chicago, Illinois, 1971). The introduction of this
European technology to the U.S. provides the incinerator-boiler plant de-
signer a wider selection of well established technology from which to choose.
Three widely used European stokers are receiving serious consideration by
North American designers. The reverse reciprocating German Martin grate is
being used for the first time in North America in the New Chicago Northwest
incinerator, and the Swiss Von Roll stokers were installed in Montreal's
Descarriers plant. The drum grate developed in Germany and used in several
European plants, has received considerable attention but has not yet been in-
stalled in an American plant.
The Chicago Northwest Incinerator is designed to burn 1600 tons of
waste per day and produce steam for sale. Most of the major components were
built by an experienced commercial organization in Germany and shipped to
Chicago. The basic design is similar to several other large incinerator plants
in Europe.
In spite of the advanced state of development of this systems, a
considerable amount of time has been required to build and get the Chicago
plant to operate smoothly. Construction was started in 1969. As of the
spring of 1972, the plant reliability has not yet reached the point where
steam could be generated for sale. Difficulty has been experienced in burn-
ing excessively wet refuse and boiler corrosion problems have been experienced.
Some of the difficulties being experienced in getting this plant into opera-
tion is due to inexperience with this type of incinerator. There is no doubt
that this and the other start-up problems will be answered and the plant put
into full operation.
From a technical standpoint this type of resource recovery plant
should present a minimum amount of technical problems because of its advanced
stage of development. Furthermore, this type of plant is usually designed
for large capacities and therefore particularly applicable to large cities.
However, care must be taken in locating the plant close to steam consumers,
since steam cannot be transported over long distances. Large cities which
have an immediate solid waste disposal problem can give immediate considera-
tion to building heat recovery incinerators because these incinerators are
one of only two resource recovery systems (composting is the other system)
which is fully developed at this time.
In addition to steam or power generation from heat recovery incin-
eration, other uses are possible. The City of Ansonia, Connecticut, employs
heat recovered from incineration to dry sludge from the city's water pollu-
tion control plant. Sludge containing less than 10 percent solids is pumped
-------
directly to a spray dryer and the dry product, containing less than 13 per-
cent moisture, is pneumatically conveyed to the furnace for burning in suspen-
sion. The Oceanside plant at Hempstead, New York, uses recovered heat for
desalination of sea water for in-plant use. A new plant at Hamilton, Ontario,
will use recovered heat to produce steam which will drive equipment such as
shredders and fans.
Although heat recovery from waste incinerators is an established
practice, there are still some technical problems, even in the most advanced
plants. The principal problems are slagging, erosion and corrosion of boiler
components, and difficulties in burning excessively wet waste.
2.1.2 Fuel recovery. The feasibility of using mixed urban refuse
as a substitute for conventional fuels in power plants and industrial fur-
naces has been under study in the U.S. in recent years. Combination fuel
fired systems have been found to be feasible and several systems have been
proposed to further demonstrate the concept.
The City of St. Louis, Union Electric Company, and the consulting
firm of Horner and Shifrin, with partial funding from EPA, have constructed
a 300 TPD (8-hour shift) processing plant for using refuse as a supplementary
fuel for electrical power plants. The refuse is milled and magnetic material
is removed. The milled material is pneumatically fed to a power plant fur-
nace where it is burned along with pulverized coal (separate nozzles are used
to inject the milled refuse into the furnace). The refuse contributes 10 to
20 percent of the total fuel.
The demonstration plant was started up April 4, 1972. The only
major changes that have been made in the original system design to date are
the substitution of a belt conveyor for a vibratory conveyor at the refuse
truck receiving pit and the substitution of a drag conveyor for a belt con-
veyor at the output from the Atlas storage bin at the power plant. The addi-
tion of an air classifier after shredding to remove heavy pieces is planned
to improve pneumatic flow and reduce pipeline wear in the boiler furnace
feed system. All of the major components in both plants are commercially
available equipment, although not necessarily shelf items.
A. M. Kinney, Inc. (consulting engineers) has also proposed a pro-
cess which recovers the thermal energy from municipal refuse by burning it
in combination with fossil fuels in conventional steam boiler furnaces. The
Kinney system utilizes a hydrapulper to convert all pulpable materials to an
aqueous slurry. Nonpulpable materials are ejected continuously from the
hydrapulper, conveyed to a drum-washer and thence to a magnetic separator
where ferrous metal is recovered. Following removal of nonfibrous materials
in a liquid cyclone, the pulped slurry is dewatered and compressed into a
-------
cake with 50 percent solid content. The solid cake can be used as a power
boiler fuel with or without additional processing depending upon the type
of boiler used. A. M. Kinney estimates that from 5 to 20 percent of the
heat input for a given furnace might come from this fuel source.
The Kinney system is only in the design stage and no pilot plant
exists at this time. However, the technical feasibility of wet grinding
municipal solid waste to produce a homogeneous slurry has been proved dur-
ing 2 years of pilot plant operation by the Black-Clawson Company and by
the operation of the Black-Clawson Solid Waste Disposal Plant in Franklin,
Ohio. A. M. Kinney has conducted engineering studies to assess the feasi-
bility of using wet grinding in the process to recover the thermal energy
from refuse in conventional boiler systems. Because the pulped and de-
watered refuse (50 percent moisture) is similar to bark and bagasse, which
contain 40 to 60 percent water and have been used successfully as boiler
fuel in pulp and sugar mills, it appears that pulped refuse, with its
greater homogeneity, more uniform water content, and smaller particle size,
would also burn successfully in power boilers.
2.1.3 Generation of electricity. A new system for recovering
energy from mixed municipal waste is being developed by the Combustion
Power Company, Menlo Park, California. In this system, called the CPU-400,
the refuse is shredded, burned in a high pressure fluid bed combuster, and
the hot gases drive a gas turbine/generator to produce electricity.
The CPU-400 is now in the early pilot plant stage; system studies
and subscale experiments have been completed and development and testing of
portions of the pilot plant are under way. Pilot plant testing to date has
been centered on three areas: (1) the shredding and classifying of the
solid waste, (2) the combustor feed system, and (3) the fluid bed combustor.
The solid waste handling subsystem has been developed and extensively tested.
Pneumatic transport of the fuel and injection at the base of the fluidized
bed has also been demonstrated satisfactorily.
Tests conducted on the fluid bed combustor have disclosed several
problems that have required changes or additions to the original system de-
sign. Foremost among the problems encountered to date are: (1) agglomera-
tion of bed material particles--a phenomenon that places an upper limit on
operational bed temperatures; (2) combustor and exhaust system deposits
formed by the impingement of aluminum oxide particles on surfaces; and (3)
elutriation of bed material.
Items (2) and (3) have led to extensive design changes in the sys-
tem. To solve the elutriation problem the original horizontal fluid bed com-
bustor with its attendant low freeboard height has been abandoned and a new
-------
vertical combustor unit designed and installed. An alumina removal chamber
has been added between the combustor and the gas cleaning train to solve the
deposit problem. The performance of the new combustor unit and alumina re-
moval system will be evaluated in a series of pilot plant tests. At this
point, the configuration of this key subsystem has not been finalized and
the performance of the total system must be viewed as an unknown at
this time.
2.1.4 High temperature incineration. Another new thermal recovery
method is high temperature incineration. The first U.S. high-temperature
incineration pilot plant was built in 1966 by American Thermogen, Inc., in
Whitman, Massachusetts. Steam and frit are the principal products of the
system. The incinerator is a shaft furnace in which refuse is charged at
the top and molten materials are withdrawn out the bottom. As the refuse
descends through the bed, it undergoes partial pyrolysis and eventual com-
bustion in the lower portion of the furnace. The melt-down at the bottom
of the furnace is accomplished at temperatures of about 3000°F by burning
auxiliary fuel, either oil or gas. A similar system is being developed by
Torrax Systems, Inc., at North Tonawanda, New York.
2.2 Materials Recovery Processes
2.2.1 Fiber recovery. Cellulose comprises from 40 to 50 percent
(wet basis) of typical mixed municipal waste, and most of the cellulose is
paper. Both wet and dry process fiber reclaiming systems have recently
been developed. The Black Clawson Company, Middleton, Ohio, has developed
a wet process system for recovering paper pulp from mixed municipal solid
waste. In addition to the recovery of paper pulp, steel, glass, aluminum
and ash are also recoverable. The heart of the Black Clawson system is a
Hydrapulper which receives all incoming waste, except for large, bulky
items. Friable materials such as food waste, paper, plastic, rubber, rags,
glass, and wood are mixed with water and pulped into a slurry. Heavier
objects are ejected from the bottom of the pulper and passed through a mag-
netic separator which recovers the ferrous metal portions. The glass and
aluminum separations will be accomplished with an air classifier. An
optical sorter will be used to separate clear glass from colored glass,
developed by the Sortex Company of North America.
The Black-Clawson Hydraposal/Fibreclaim demonstration plant at
Franklin, Ohio, has been in operation since June 1971. The design capacity
of the plant is 150 tons of raw waste per 24-hour day. However, the plant
has averaged only about 50 tons per day because of a lack of delivery of
refuse. There is a charge made to dump raw refuse at the plant and landfill
10
-------
sites have been competing for the area refuse. Nevertheless, an hourly
throughput of about 8 tons per hour has shown that the plant is capable of
meeting the design capacity. The plant burns about 32 percent of the total
incoming waste.
At the present Black-Clawson is recovering only paper pulp and
magnetic metals. Equipment to recover the glass and aluminum will be added
in late 1972. To date, they have been landfilling the mixture of glass and
nonmagnetic metals. They have experienced lipids and fines in the pulp
which is undesirable from both the end pulp product (asphalt roofing felt)
and then it tends to clog the processing equipment (which adds to the
maintenance costs). They are in the process of adding equipment to reduce
the contaminants. This involves treating the pulp with steam and caustics,
and subsequent washing.
The Franklin Institute, Philadelphia, Pennsylvania, is in the pro-
cess of developing a dry process primarily for extracting paper from mixed
municipal refuse. Shredded refuse is screened and sent through a ballistic
separator. The ballistic separator consists of a rotating wheel which hurls
the material in a horizontal direction. A downward blast of air causes the
lightest materials (paper and plastics) to drop out first and the heaviest
materials (metals, glass, etc.) last. A plastics collector separates the
plastics from the paper. Laboratory tests indicate an effective separation
of paper (90 to 95 percent purity). A pilot plant of the system has been
constructed and full scale tests were initiated July 1972.
2.2.2 Incinerator residue recovery. The Bureau of Mines, College
Park, Maryland, has developed a method for processing incinerator residues
on a continuous basis to reclaim the metal and mineral values. The process
utilizes conventional and proven mineral engineering equipment consisting
of a series of shredding, screening, grinding, and magnetic separation
procedures. Metallic iron concentrates, nonferrous metal composites, glass
fractions, and fine carbonaceous ash tailings are products of the system.
A demonstration plant is to be built at Lowell, Massachusetts.,
2.3 Pyrolysis Processes
Considerable potential exists for reforming, by pyrolysis, the
organic portion of municipal solid wastes into lower molecular weight com-
pounds having significant economic value. Because pyrolysis reactions
often termed "destructive distillation," can be conducted in the absence of
oxygen or in controlled oxygen environments, product composition can be
regulated. Unlike combustion in an excess of air, which is highly exo-
thermic and produces primarily heat and carbon dioxide, pyrolysis of or-
ganic material is analogous to a distillation process and is endothermic.
11
-------
The high temperatures (1000 to 20008F) and lack of oxygen result in a chemi-
cal breakdown of the waste organic materials into three component streams:
(1) a gas consisting primarily of hydrogen, methane, carbon monoxide, and
carbon dioxide, (2) a "tar" or "oil" that is liquid at room temperature and
includes organic chemicals such as acetic acid, acetone, methanol, and (3)
a "char" consisting of almost pure carbon plus any inerts (glass, metals,
rock) that enter the process unit. Residence time, temperature, and pressure
can be controlled in the pyrolysis reactor to produce various product combina-
tions.
Laboratory and pilot plant pyrolysis units have been successfully
constructed and operated, and these units have demonstrated the technical
feasibility of the pyrolysis of municipal refuse. Laboratory investigations
of the pyrolysis of various organic wastes have been conducted at the
University of California (Berkeley), Bureau of Mines, Rensselaer Polytechnic
Institute, New York University, and the Utilities Department of the City of
San Diego, California. Batch retorts, fluidized beds, and rotary kilns have
been successfully used as reactors in these laboratory studies. Pilot plant
studies of pyrolysis systems for municipal wastes have been conducted by
Garrett Research and Development Company, Monsanto1s Enviro-Chem Systems,
Battelle Northwest, the University of West Virginia, and Union Carbide.
Garrett Research and Development Company has a resource recovery
system designed to recover salable synthetic heating fuels, glass, and
magnetic metals from mixed municipal refuse. The system is an outgrowth
of nearly 4 years of intensive research into methods of production of syn-
thetic fuels. The system contains all operations necessary for receiving,
handling, shredding, and classifying solid waste; for separation of mag-
netic metals and glass from the classified waste; for pyrolyzing the organic
fractions of the waste; and for the recovery of oil and char generated
during the pyrolysis step.
The heart of the Garrett system is the flash pyrolysis process.
The pyrolysis process has been studied in considerable detail in a labora-
tory reactor system for over a year. A wide variety of organic materials
were used as feed materials in these tests. The laboratory pyrolysis tests
defined the operating conditions needed to maximize the yields of heating
fuels. The laboratory test program demonstrated that the pyrolysis reactor
can be operated in either a liquefaction or gasification mode. Garrett
claims that over one barrel of oil per ton of input refuse can be produced
in the liquefaction mode, while 6,000 scf of gas with a heating value of
800 Btu/ft^ can be produced in the gasification mode without relying on
additional fuel sources.
12
-------
In order to obtain the high yields of oil and gas, the feed to
the reactor must consist of essentially a pure, dry organic material of
small particle size. To meet this requirement, the first stages in the
Garrett process involve extensive shredding, air classification, screening,
and drying steps. The materials handling and preparation section is one
of the most comprehensive proposed for any current recovery system. A
150 ton per day demonstration plant is to be built at San Diego, California.
The Monsanto "Landgard" System is based on pyrolysis with the
primary objective being the disposal of all types of municipal solid waste
while offering practical opportunities for resource recovery. The Landgard
systems encompass all operations for receiving, handling, shredding, and
•pyrolyzing solid waste; for quenching and separating the residue from
pyrolysis; for generating steam from waste heat, and for purifying the off-
gases.
A rotary kiln is utilized as the pyrolysis reactor in the
Monsanto system. A prototype or pilot plant of 35 TPD capacity was oper-
ated by Monsanto for nearly 3 years at St. Louis, Missouri. All components
for the system were tested to some degree at the pilot plant. Although
long-term, steady-state operation was not performed during pilot plant
operation, sufficient experience was gained from the pilot plant operation
to demonstrate system feasibility. A 500 ton per day demonstration plant
is to be built at Baltimore, Maryland.
The city of Charleston, West Virginia, has recently proposed a
Regional Resource Recovejry System that incorporates a pyrolysis system as
the key unit process. The pyrolysis system is an outgrowth of research
work conducted by Professor Richard Bailie at the University of West
Virginia at Morgantown, West Virginia. The Charleston system utilizes twin
fluid beds, the first bed acts as a pyrolyzer, and the second bed as a
combustor. Shredded and air classified refuse is fed to the pyrolyzer which
is operated at about 1400°F. Gas, char and some tar are produced in the
pyrolyzer. The gas produced in the pyrolyzer has a heating value of about
400 Btu/ft^. The char and tar are subsequently burned in the fluid bed
combustor to provide the heat to operate the pyrolyzer unit. Energy re-
leased by the combustion of the char and tar is reported to be sufficient
to maintain the pyrolyzer at operating temperature without the need of
supplemental energy input. Professor Bailie has operated both the pyrolyzer
and combustion units independently, but both units have never been tied together
into an integrated system.
13
-------
Hercules, Inc., has designed a 500 TPD reclamation plant for the
State of Delaware which incorporates composting, pyrolysis, and materials
separation operations. Residential refuse, after removal of ferrous metals,
will be mixed with sewage sludge and composted in a Fairfield digestion unit.
Noncompostable organic components will be pyrolyzed. Inorganic residues will
be sorted and reclaimed. Industrial and commercial wastes will be handled
in a similar fashion, following a preliminary reclamation stage. The pyroly-
sis unit is a Herreshoff furnaceof the type used to make wood charcoal. This
equipment is a multiple chamber, continuous feed and discharge unit with me-
chanical movement of material from chamber to chamber in the furnace. A
demonstration plant is to be built for the State of Delaware.
Battelle Northwest has been conducting pyrolysis-incineration re-
search for EPA and the City of Kennewick, Washington. An outgrowth of this
research has been the construction and operation of pilot plant equipment
capable of processing about 2 tons per day of refuse on a batch basis. The
heart of the process is a closed vertical reactor where the refuse is pro-
gressively dried, charred, and finally oxidized at relatively low temperatures
under carefully controlled conditions. The refuse undergoes three trans-
formations in a packed bed settling under the force of gravity while reactant
and combustion product gases rise counter-current to the direction of solids
movement.
To produce a heating gas with the Battelle process the solid char,
the product of pyrolysis in the upper portion of the reactor, is oxidized in
the bottom part of the reactor by a mixture of oxygen (from either air of
commercial oxygen) and steam. The hot reaction product gases continue up-
ward and release their heat to cause charring of the entering refuse. Fi-
nally, the residual heat in the gases evaporates moisture from the entering
refuse at the top of the reactor. The gases which leave the reactor contain
hydrogen, oxides of carbon, water vapor, and a mixture of hydrocarbons.
These gases may be cleanly burned in a secondary burner since they contain
no ashy materials. Alternately, they may be processed for recovery of or-
ganic compounds, further treated to produce a heating gas, or processed
still further to yield a 75 percent"hydrogen and carbon monoxide mixture
which may be used to synthesize methane.
Linde Division of Union Carbide Corporation recently announced
the development of a high temperature incinerator system that utilizes oxy-
gen in place of air to develop the requisite high temperatures in the melt
zone. The Carbide system utilizes a vertical furnace into which all munici-
pal waste can be fed, including garbage, paper, wood, rubber, all metals,
plastics, glass, and bulky items. As with other high-temperature incinerators,
the Oxygen Refuse Converter is primarily a refuse disposal system and not a
resource recovery system, although the off gases can be cleaned for use as
an industrial fuel gas. A 5 ton per day pilot plant has been in operation
14
-------
at Tarrytown, New York, for about 9 months. The objective of the tests con-
ducted during this period were to determine furnace operating characteristics,
oxygen consumption rates, and the influence of refuse composition on furnace
performance.
2.4 Composting
Composting of municipal refuse has been practiced in Europe and
the U.S. for many years. European activity in composting has included re-
search in such diverse fields as engineering technology, public health and
pathogen survival, use in strip mine reclamation, use in vineyards and use
in general agriculture. The technology of composting is well advanced and
there are no real technological barriers to making compost.
In the United States, composting plants have been established in
various communities over the last 20 years. In general, these plants have
met with little success and most have closed. The major problem for these
plants is the lack of a viable market for the compost. Currently, only two
plants, Altoona FAM, Inc., Altoona, Pennsylvania, and Ecology, Inc., Brooklyn,
New York, are known to be operating on a regular basis.
In the Fairfield-Hardy Process used at Altoona, refuse is ground
in a wet pulper, followed by dewatering presses before it is fed into the
digester for a 5-day processing cycle. Stirring is provided in the digester
by augers suspended from a rotating bridge in the circular tank. Air is
provided by means of a blower and air pipes embedded in the floor of the
tank. The digestion system of Fairfield Engineering Company appears to of-
fer a superior engineering design, a more automated operation than other
compost techniques, and an ability to produce a superior humus product.
The Varro composting process used by Ecology, Inc., is distinguished
from other composting processes by several factors. First, the digester can
compost refuse with a paper content of up to 90 percent (most composting
plants send paper to landfills since they cannot readily process it). Second,
noneompostable materials do not have to be separated from compostables before
beginning the composting process; only ferrous metals (removed after shred-
ding) do not go through the digester. Third, the digester permits control of
variables in the decomposition process and consequently enables production
of a compost with uniform composition. Also, nutrients are added to the
compost to encourage its use as fertilizer.
15
-------
2.5 Chemical Systems
Chemical methods that have been suggested for converting municipal
refuse into usable products include hydrolysis, hydrogenation, wet oxidation,
photo degradation and anaerobic digestion.
These methods use only the cellulosic portion of municipal refuse,
so that separation and pretreatment of the raw refuse is required.
Hydrolysis of cellulosic waste to produce protein and glucose is
the only process that has been tested at the pilot plant level. Hydrogena-
tion and wet oxidation have been studied in laboratory equipment, while
photodegradation and anaerobic digestion are in the conceptual state.
A pilot plant for the production of single-cell protein from waste
sugarcane bagasse has been designed, constructed, and operated at Louisiana
State University. The pilot plant's equipment can be grouped into five dis-
tinct process sections: cellulose-handling, treatment, sterilization, fer-
mentation, and cell harvesting. The plant was designed so that it could
operate in both batch and continuous-flow modes. The initial operation of
the pilot unit has been limited to a single waste celluosic substrate, sugar-
cane bagasse. Purified ground wood pulp has also been used as a control sub-
strate in several runs. Single-cell protein with a crude protein content of
50 to 55 percent has been produced.
16
-------
CHAPTER III
ECONOMICS OF BASIC RESOURCE RECOVERY PROCESSES
3.0 Introduction
The economic aspects of eight basic resource recovery processes
were examined, along with the two primary nonrecovery solid waste disposal
methods. The objective was to develop the economic evaluation of all basic
processes on consistent, criteria in order to have a consistent comparative
analysis. The conventional disposal techniques--sanitary landfill and in-
cineration—were used as bases for weighing the incremental costs and bene-
fits associated with each of the resource recovery processes.
Presently, the close-in sanitary landfill is the lowest cost en-
vironmentally acceptable means of disposal for mixed municipal waste. When
land costs are prohibitive, or when suitable landfill sites are not available
within a reasonable distance, either a remote landfill or incineration have
generally been the only feasible disposal alternatives. These three dis-
posal options were the base against which all other concepts were measured.
The eight basic resources recovery processes examined were:
1. Incineration with recovery of materials from the incinerator
residue. (Example: Nonrecovery waste incinerator and USBM Residue Recovery
Process.)
2. Incineration with heat recovery, used to produce steam for in-
dustrial applications. (Example: Chicago Northwest Incinerator.)
3. Incineration with heat recovery, used to produce steam for in-
dustrial applications and recovery of materials from the incinerator residue.
(Example: Chicago Northwest Incinerator and USBM Residue Recovery Process.)
4. Incineration with heat recovery, used to generate electric
power either for a specific industrial application or for distribution
through an existing utility network. (Example: Osaka, Japan, Power Generating
Plant.)
5. Pyrolysis, with recovery of oil, char and inorganic materials.
(Example: Garrett Pyrolysis Process.)
6. Composting, involving the production of humus material from the
biodegradable organic portion of the mixed refuse, and recovery of inorganic
materials from the nonbiodegradable portion. (Examples: Hercules and Fairfield-
Hardy Process.)
17
-------
7. Materials recovery (paper, aluminum ferrous metals and glass)
involving separation of the mixed refuse into its marketable commodity com-
ponents. (Examples: Franklin Institute and Black-Clawson Processes.)
8. Recovery of organics for use in public utility boiler furnaces
as a supplementary fuel, along with ferrous metal recovery. (Examples:
Horner and Shifrin and A. M. Kinney Processes.)
The economic evaluation of these systems was based on a munici-
pally-owned and operated facility with an economic life of 20 years, re-
ceiving 1,000 tons per day of mixed domestic and commercial refuse, and
operated on a 24 hour per day, 300 day per year schedule. (The rationale
for these assumptions are given in Section 3.1.) Also, the effects of
various plant capacities were examined.
A "typical" mixed municipal refuse was used in the analysis.
raw wastes were assumed to consist of:
The
Waste Component
Paper
Glass
Ferrous metals
Nonferrous metals
Plastics, leather, rubber,
textiles, wood
Garbage and yard wastes
Miscellaneous (ash, dirt,
etc.)
Total Dry Weight
Moisture
Total Refuse Quantity
Percent
by Weight
33.0
8.0
7.6
0.6
6.4
15.6
1.8
100.0
Quantity
Available
(tons per year)
99,000
24,000
22,800
1,800
19,200
46,800
5.400
219,000
81.000
300,000
Because of the waste's moisture content, a 1,000 TPD operation
has only 700 to 800 TPD of potentially recoverable resources on a dry weight
basis, a point often overlooked in the analysis of recovery systems. While
the composition of mixed municipal wastes will vary widely both regionally
and seasonally, the above proportions are believed to be reasonably repre-
sentative of what would be encountered in a typical large metropolitan area.
18
-------
Probably the least reliable assumptions employed in the economic
analyses dealt with the value and marketability of the recovered resources.
It has been assumed that the products recovered from the mixed wastes will
be sold in the quantities in which they are produced and at the prices in-
dicated. It must be recognized, however, that markets may or may not exist
for some of the recovered resources at any specific time and location, and
prices may fluctuate over a wide range. The effects of price variations on
revenues and net operating costs are covered in another section.
3.1 Basic Conditions for the Detailed Economic Analysis
The analyses are not based on any specific organizations' processes.
However, the economic data of various system developers were used as a bench-
mark for the economic analysis.
Costs can be expected to vary widely according to local conditions,
and specific design considerations would be necessary to arrive at an appro-
priate cost for a particular plant at a given location. A number of assump-
tions were, therefore, necessary in developing the costs shown here; these
assumptions are described in detail so that they can be readily adjusted
for prevailing local conditions, and to define the boundaries under which
our economic analysis was developed. It is emphasized here that the economics
are generalized and "national average" data for 1971 and cannot be construed
as typical for any geographic location or conditions.
Ownership. The evaluation was based on a municipally-owned and
operated facility; this affects the annual fixed costs that are related to
the capital investment. The impact of facility ownership on fixed costs is
shown in Table 1. Since most waste reclamation systems are capital intensive
(i.e., high capital costs per unit of plant capacity), municipally-owned
plants offer a decided and substantial cost advantage over privately-owned
plants. Tax-free municipal bonds can be sold at about a 5 percent annual
rate, while high-grade industrial bonds would yield some 8 percent when held
until maturity. Municipalities also have an advantage over private owners
with respect to property taxes and income taxes.
Plant capacity. A 1,000-TPD plant was used as the basis for the
economic analysis. After capital investment was estimated for the 1,000-TPD
plant, appropriate scale factors were developed for each major system com-
ponent, and the corresponding investment, operating costs, revenue and net
operating costs were projected for facilities having daily capacities of
250, 500, and 2,000 tons.
Operating schedule. The operating schedule was assumed to be
similar to an industrial plant so the operating schedule used was 300 days
per year and 24 hours per day. Any change toward say a 5-day week and 8- or
16-hour schedule has a dramatic effect on capital investment and operating
19
-------
TABLE 1
ANNUAL FIXED CHARGE RATIOS FOR INVESTED CAPITAL
Amortized Investment
Capital Recovery (5 years)
Fixed Investment
Capital Recovery (20 years)
Insurance
Administrative and General
Property Taxes
Total
Recoverable Investment
Interest only
Municipal Private
Ownership!/ Ownership^/
0.231
0.095
0.050
0.275
0.080
0.005
0.010
0.000
0.131
0.005
0.010
0.015
0.161
0.116
\l Interest on municipal debt estimated at 5.0 percent.
2J Cost of private capital estimated at 11.6 percent, based on 70 percent
debt financing at 8.0 percent and 30 percent equity capital at 20.0
percent.
Source: Midwest Research Institute
20
-------
costs for the same throughput quantity (300,000 TPY). Thus, the assumptions
for the base operating schedule should be carefully placed in perspective for
comparative purposes.
Capital requirements. Capital is divided into three broad categories
for estimating purposes: (1) amortized investment; (2) fixed investment; and
(3) recoverable investment.
Amortized investment includes engineering costs, research and de-
velopment expenditures, and an allowance for a period of plant startup. The
capital requirements in this category are not depreciable nor can they be
written off as operating expenses during the year in which they are incurred.
The assumption here is that they will be charged off over a 5-year period,
with interest computed at a rate of 5 percent annually.
Fixed investment represents the direct costs of plant facilities;
these were, in turn, placed into four broad categories: (1) waste handling,
preparation and storage equipment and facilities, including, wherever appro-
priate, the equipment and machinery needed for crushing grinding or otherwise
sizing the raw wastes for further processing; (2) facilities for waste con-
version, whether accomplished by combustion, mechanical or other processes;
(3) resource recovery processes, involving in some cases the physical or
mechanical sorting of marketable waste components, and in other cases the
recovery and processing or utilization of combustion products; and (4) aux-
iliary and support facilities covering structures, utilities, environmental
control equipment, and all other plant requirements. In converting total
fixed investment to its equivalent annual cost, a rate of 9.5 percent was
applied (capital recovery at 5 percent interest over 20 years (or 8 percent
per year) plus insurance, administrative and general expenses at 1.5 percent
per year of fixed investment).
Recoverable investment encompasses those requirements for capital
that, on completion of the project, will be returned to the project's owners.
In this case, the recoverable investment tied up in the project includes two
items: (1) land; and (2) sufficient working capital to cover the system's
'costs of operation for a 3-month period.
Annual costs. Operation of each system includes: (1) direct
operating costs—labor, materials, supplies, utilities, variable overheads
and other expenses related directly to the amount of waste material handled;
(2) fixed costs--those incurred with time rather than with the scale of
plant operation, and covering the costs of maintaining and administering the
overall operation; and (3) capital charges—those directly attributable to
the amount of capital tied up in the facility. These capital charges, in
turn, cover capital recovery on amortized investment (depreciation, and
interest); insurance and administrative charges applied to fixed plant; and
interest on the recoverable investment.
21
-------
Operating costs for each system were developed in the same way
as fixed investment, by determining the direct labor, materials and utility
requirements associated with each major system function. Total direct oper-
ating costs for a particular system, then, were found simply by totaling the
separate costs for the appropriate functions of processes required in the
system's operation. Labor wage rates of $5 per hour were used throughout,
plus a 30 percent allowance for payroll burden; utility costs were charged
at $0.50 per million Btu fuel and $0.01 per kwh for electrical energy for
quantities required by the function or process in question.
Finally, the net annual costs of operation were computed for each
basic process, both as a total and on a unit basis. The resultant values
represent the estimated net operating cost of processing for recovery of
300,000 tons per year of mixed municipal refuse under the specified condi-
tions. Table 2 summarizes the bases used in developing the capital and
operations cost estimates.
Revenues. The estimated value for recovered resources was based
on the "average" market value of comparable competitive commodities or
products as obtained from published or industrial sources. These values
were also adjusted for the quality of the recovered product, and for any
special handling facilities that a potential buyer would have to provide.
Then, an allowance was made for freight and brokerage charges if the value
commonly quoted is on a delivered basis, to give the recovered product
value FOB the resource recovery plant. For example, the value of ferrous
metals was based on the average delivered price of No. 2 bundles (about
$20 per net ton), less $8 per ton for freight, brokerage, and a minor
scrap quality adjustment. The value of paper fiber was based on estimates
of the price of mixed paper for combination paperboard. The value of refuse
as a coal substitute was derived from a base coal value of $0.30 per mm Btu,
less an allowance of $0.05 per mm Btu for lower refuse heat content per ton
and special handling requirements and capital investment at the utility fur-
nace site.
Not all of any given commodity in the waste can be recovered.
The yields are based on recoverable quantities reported by various system
developers for various commodities with some estimates by MRI of recovery
system efficiency. The starting point was the average waste composition
given earlier, adjusted for system recovery efficiency for each commodity
recoverable (e.g., paper, oil, glass, etc.).
The revenue values used in the analysis are not absolutes, but
are MRI's best estimates of the average value of recovered commodities or
products per unit in competitive market times.
22
-------
TABLE 2
BASES FOR CAPITAL AND OPERATING COST ESTIMATES
Capital or Cost Item
Engineering, R&D
Startup Costs
Fixed Investment
Land and Site Improvements
Working Capital Requirements
Annual Operating Costs
Annual Fixed Costs
a/
Annual Amortized Investment Charge^
Annual Fixed Investment Charge3-'
Annual Recoverable Investment Charge
Basis
12.0 Percent of Fixed Investment
Two Months Operating Costs
Estimated Directly
Estimated Directly
Three Months Operating Costs
Estimated Directly
1.0 Percent of Total Capital Re-
quirement Plus 5.0 Percent of
Operating Costs
23.1 Percent of Amortized Investment
9.5 Percent of Fixed Investment
5.0 Percent of Recoverable Investment
a/ See Table 1.
23
-------
The gross value of recovered resources was calculated based on
yield, unit price, and the commodity profile for each system. These resource
values are given in Table 3.
The further assumption was made that all of the commodity or product
recovered from a system could be sold at the market values used. Of course,
the actual conditions of a specific location and recovered product profile may
vary widely from these "average" values. However, the revenues were carefully
developed and considered realistic for this economic analysis.
The economic data for each process are summarized in two tables.
The first table shows estimated capital requirements for the process and the
second table summarizes its estimated costs of operation and revenues.
3.2 Economics of Basic Systems
3.2.1 Incineration for disposal. The economic data for incinera-
tion were based on average investment requirements for waste disposal furnaces.
The capital investment estimate for a 1,000-TFD plant was $9,299 per daily
ton. However, there are wide ranges of capital investment estimates reported
for incineration, ranging from $5,000 to $17,000 per daily ton of installed
capacity, with the most recent citations exceeding $10,000 per daily ton.
It is likely that higher are becoming more prevalent today.
Likewise, wide ranges are reported in estimated operating costs
of incinerators, generally in the range of $5 to $12 per ton, with the most
recent estimates toward the high end. The MRI base estimate of operating
cost for a 1,000-TPD incinerator was $7.68 per ton including capital costs.
However, the operating conditions make a significant difference in operating
costs, ranging from $10.37 per ton at 250 TPD, down to $6.65 per ton at
2,000 TFD. All of the data in Tables 4 and 5 are for a waste disposal in-
cinerator as a "bare bones" operation without resource recovery. Therefore,
there is no resource value. Waste incineration was treated as one disposal
alternative as a base for comparison of resource recovery options—four of
which are directly related to incineration and four of which are not.
3.2.2 'incineration with residue recovery. The model for the in-
cinerator residue recovery system was Bureau of Mines work. The data were-
based on a system sized to process the residue output of the incinerator
raw refuse input. The incinerator residue system capacities were scaled
at 25 percent of the input tonnage or 250 TFD for a 1,000-TPD incinerator.
For a new system, the total investment for incinerator residue re-
source recovery system is simply the cost of the basic incineration process
plus the cost of the incinerator residue recovery component as an incremental
investment. Likewise, total operating costs rise by the amount necessary to
operate the incinerator residue recovery system over and above incineration.
24
-------
TABLE 3
QUANTITY AND VALUE OF RECOVERABLE RESOURCES IN
300,000 TONS OF MIXED WASTE
Resource
Paper
Glass
Ferrous Metal
Ferrous Metal (incin-
erator residue)
Nonferrous Metal
Humus
Recoverable
Quantity-Units
(yield)
45,000 tons
16,800 tons
20,400 tons£/
12,700 tons*/
1,200 tons
75,000 tons
Estimated Value
FOB Recovery
Plant ($/unit)
15
10
12
10
200
6
Total Total
Value Value, Dollars
($) Per Input Ton
675,000 2.25
168,000 0.56
244,800 0.82
127,000 0.42
240,000 0.80
450,000 1.50
Steam
Electric Energy
2.0 x 10° m Ib
200 x 10° kwhr
Synthetic Fuel Oil 1.44 x 106 mm Btu
Synthetic Fuel Gas 2.0 x 106 mm Btu
Fuel (coal subsittute) 2.7 x 106 mm Btu
0.50 1,000,000 3.33
0.006 1,200,000 4.00
1,008,000 3.36
1,000,000 3.33
0.70
0.50
0.25
675,000 2.25
£/ Ferrous metal from incinerator residue was valued at $10 per ton to reflect
the fact that it is a lower quality product; also the recovery is lower
from incinerator residue.
Note: The location of a plant with respect to it s markets may greatly change
the FOB plant value because of freight costs; these are "average"
values. The locale may also mean a much different product value be-
cause of local condition; e.g., energy costs vary widely by geo- •
graphic location in the county.
25
-------
TABLE 4
TOTAL CAPITAL REQUIREMENTS FOR CONVENTIONAL INCINERATION
(1,000 TPD Raw Waste Input Capacity)
Amortized Investment
Engineering R&D $ 924,000
Plant Startup 190.000
Total Amortized Investment $ 1,114,000
Fixed Investment
Waste Handling, Preparation and Storage $ 1,040,000
Waste Conversion 2,600,000
Resource Recovery Processes 0
Auxiliary and Support Facilities 4.060.000
Total Fixed Investment $ 7,700,000
Recoverable Investment
Land and Site Improvements 200,000
Working Capital 285.000
Total Recoverable Investment $ 485,000
Total Capital Requirement $ 9,299,000
Total Capital Requirement at:
250 TPD Capacity $ 3,180,000
500 TPD Capacity $ 5,440,000
2,000 TPD Capacity $15,900,000
26
-------
TABLE 5
ANNUAL OPERATING COSTS FOR CONVENTIONAL INCINERATION
(300,000 TPY Raw Waste Throughput)
Per Ton of
Annual Costs Total Waste Input
Operating Costs $1,140,000 $3.80
Fixed Costs 150,000 0.50
Capital Charges
Amortized Investment $257,000
Fixed Investment 732,000
Recoverable Investment 24.000
Total Capital Charges 1,013,000 3.38
Total Annual Cost of Operation $2,303,000 $7.68
Effect of System Capacity on Operating Costs
250 TPD 500 TPD 1.000 TPD 2.000 TPD
Total Annual Cost $778,000 $1,347,000 $2,303,000 $3,990,000
Resource Value 0 0 0 0
Net Annual Cost $778,000 $1,347,000 $2,303,000 $3,990,000
Net Cost per Ton $10.37 $8.98 $7.68 $6.65.
27
-------
The incinerator is considered an integral part of the "preparation" step for
an incinerator residue processing system and thus is included in the total
operating costs for disposal of organics.
Revenues are derived from ferrous metals, nonferrous metals (alu-
minum) and glass. The resource values assume that the output is salable at
the prices listed in Table 3. Assuming that the incinerator residue pro-
duces a salable product, the revenues appear to make this a feasible re-
covery alternative where waste incineration is practiced.
The economic summary data are given in Tables 6 and 7. They show
that net operating cost would range from $10.45 per ton at 250 TPD to $5.88
per ton at 2,000 TPD of incoming waste.
In terms of incremental costs, the addition of a residue recovery
system to a 1,000 TPD incinerator increases the total capital requirement
by $1,377,000, and adds $386,000 annually to total operating costs. The
value of recovered resources, though, results in a net savings of $159,000
annually, representing a return of 10.8 percent on the incremental invest-
ment .
Should the residue recovery system be added onto an existing in-
cinerator, the economics would be different since the incinerator could be
treated as a "sunk cost" in that case.
MRI has some reservations about marketability of the recovered
products. The ferrous metal residue is particularly uncertain. A portion
of the ferrous metals are an unsalable residue of scale, slag and small fer-
rous pieces. The rest of the residue is contaminated with tin and copper.
Copper removal is feasible but may be impractical. Thus, the ferrous part
that is salable will find use in limited specification recycling applications.
It is, however, excellent for precipitation copper processing, but this mar-
ket is restricted by limited demand and geography.
By contrast, the aluminum portion can be separated by flotation
techniques and is quite salable, although high temperatures of some furnaces
may vaporize portions of the aluminum in waste.
The glass portion is less desirable than glass that has not been
incinerated. However, it appears to be in a satisfactory condition to up-
grade and color sort. It may be less desirable for direct recycling than for
use in other applications (e.g., bricks).
In summary, the market potential for the three recovered materials
is fair to good but far from exciting.
28
-------
TABLE 6
TOTAL CAPITAL REQUIREMENTS FOR INCINERATION WITH RESIDUE RECOVERY
(1,000 TPD Raw Waste Input Capacity)
Amortized Investment
Engineering, R&D $1,051,000
Plant Startup 226.000
Total Amortized Investment $1,277,000
Fixed Investment
Waste Handling, Preparation and Storage $1,040,000
Waste Conversion 2,600,000
Resource Recovery Processes 730,000
Auxiliary and Support Facilities 4.390.000
Total Fixed Investment • $8,760,000
Recoverable Investment
Land and Site Improvements $ 300,000
Working Capital 339.000
Total Recoverable Investment $ 639,000
Total Capital Requirement $10,676,000
Total Capital Requirement at:
250 TPD Capacity $ 3,650,000
500 TPD Capacity $ 6,240,000
2,000 TPD Capacity $18,260,000
29
-------
TABLE 7
ANNUAL OPERATING COSTS FOR INCINERATION WITH RESIDUE RECOVERY
(300,000 TPY Raw Waste Input)
Per Ton of
Annual Costs Total Waste Input
Operating Costs $1,355,000 $4.52
Fixed Costs 175,000 0.58
Capital Charges
Amortized Investment $295,000
Fixed Investment 832,000
Recoverable Investment 32.000
Total Capital Charges $1.159.000 3.86
Total Annual Cost of Operation $2,689,000 $8.96
Value of Recovered Resources
Ferrous Metals $127,000
Nonferrous Metals 240,000
Glass 168.000
Gross Value of Recovered Resources $ 535.000 $1.78
Net Annual Cost of Operation $2,154,000 $7.18
Effect of System Capacity on Operating Costs
250 TPD 500 TPD 1.000 TPD 2.000 TPD
Total Annual Cost $918,000 $1,571,000 $2,689,000 $4,600,000
Resource Value 134.000 268.000 535.000 1.070.000
Net Annual Cost $784,000 $1,303,000 $2,154,000 $3,530,000
Net Cost Per Ton $10.45 $8.68 $7.18 $5.88
Net Gain Over Con- $0.08 $0.30 $0.50 $0.77
ventional Incinera-
tion Per Input Ton
30
-------
3.2.3 Incineration with heat recovery. The recovery and sale of
heat as steam is economically attractive with conventional waste incinera-
tion and with high temperature slagging incinerators. Tables 8 and 9 give
the economic data summary. Net operating costs vary widely according to
operating conditions, of course, and are estimated at $10.85 per ton to
$5.55 per ton for the base comparison cases of 250 TPD to 2,000 TPD plants.
On an incremental basis, the addition of a steam recovery package gives the
whole system an operating cost reduction ranging from $0.18 per ton at 500
TPD, to $1.10 per ton at 2,000 TPD. This is not a large benefit and is, of
course, derived only from the organic part of the waste that is incinerated
for disposal at the steam value given in Table 3.
Steam recovery operations face some rather special market limita-
tions. While heat is a universally usable energy source, it is limited to
very short transport distances. Thus, there must be a customer near the
heat source with requirements suited to the particular incineration opera-
tion. In past years, steam recovery has often complicated operation of
waste disposal operations, because waste burning and contract heat delivery
requirements often get "out of phase." The new heat recovery techniques
appear to be more technically manageable, but the limitations of the waste
incinerator and steam customer interface are still severe. In addition,
the value of steam varies widely. This approach to resource recovery gives
an inflexible situation—steam is delivered as produced or lost; and it must
be delivered in the contracted quantities requiring standby fuel for periods
of low refuse heat value.
It appears that heat recovery is an attractive method under very
restricted conditions. From a practical standpoint, the market potential
is quite restricted. By contrast, the economic and institutional barriers
to steam recovery appear to be much less restrictive in foreign countries.
3.2.4 Incineration with steam generation and residue recovery.
The various resource recovery components and subsystems can be combined in
many different ways. One such logical combination is steam generation
coupled with incinerator residue recovery. Here, the same comments apply
as to the concept considered individually in the preceding sections.
Tables 10 and 11 summarize the pertinent economic data for this
combination of alternatives. As would be expected, the capital requirement
of $11.7 million is higher than for either residue recovery or steam gener-
ation alone, and operating costs of $11.69/ton are substantially greater.
However, the value of recovered resources, at $5.12 per ton, when credited
against the annual operating costs, results in a net operating cost of just
$6.57 per ton at the 1,000-TPD level. Since this net cost is significantly
lower than for either steam generation or residue recovery by themselves,
the addition of residue recovery capabilities appears to be economically
attractive in situations where steam generation can be justified.
31
-------
TABLE 8
TOTAL CAPITAL REQUIREMENTS FOR INCINERATION WITH STEAM RECOVERY
(1,000 TPD Raw Waste Input Capacity)
Amortized Investment
Engineering, R&D $1,138,000
Plant Startup 276.000
Total Amortized Investment $1,414,000
Fixed Investment
Waste Handling, Preparation and Storage $1,040,000
Waste Conversion 2,600,000
Resource Recovery Processes 1,200,000
Auxiliary and Support Facilities 4.640.000
Total Fixed Investment $9,480,000
Recoverable Investment
Land and Site Improvements $ 300,000
Working Capital 413.000
Total Recoverable Investment $ 713.000
Total Capital Requirement $11,607,000
Total Capital Requirement at:
250 TPD Capacity $ 3,970,000
500 TPD Capacity $ 6,790,000
2,000 TPD Capacity $19,850,000
32
-------
TABLE 9
ANNUAL OPERATING COSTS FOR INCINERATION WITH STEAM RECOVERY
(300,000 TPY Raw Waste Input)
Per Ton of
Annual Costs Total Waste Input
Operating Costs $1,654,000 $ 5.51
Fixed Costs 199,000 0.66
Capital Charges
Amortized Investment $ 327,000
Fixed Investment 900,000
Recoverable Investment 36.000
Total Capital Charges $1.263.000 4.21
Total Annual Cost of Operation $3,116,000 $10.38
Value of Recovered Resources
Steam $1.000.000
Gross Value of Recovered Resources $1.000.000 $ 3.33
Net Annual Cost of Operation $2,116,000 $ 7.05
Effect of System Capacity on Operating Costs
250 TPD 500 TPD 1.000 TPD 2.000 TPD
Total Annual Cost $1,064,000 $1,820,000 $3,116,000 $5,330,000
Resource Value 250.000 500.000 1.000.000 2.000.000
Net Annual Cost
Net Cost Per Ton
Net Gain Over Con-
ventional Incinerat-
ing Per Input Ton
33
$ 814,000
$10.85
($0.48)
$1,320,000
$8.80
$0.18
$2,116,000
$7.05
$0.63
$3,330,000
$5.55
$1.10
-------
TABLE 10
TOTAL CAPITAL REQUIREMENTS FOR INCINERATION WITH STEAM AND RESIDUE RECOVERY
(1,000 TPD Raw Waste Input)
Amortized Investment
Engineering, R&D $1,265,000
Plant Startup 312.000
Total Amortized Investment $1,577,000
Fixed Investment
Waste Handling, Preparation and Storage $1,040,000
Waste Conversion 2,600,000
Resource Recovery Processes 1,930,000
Auxiliary and Support Facilities 4.970.000
Total Fixed Investment $10,540,000
Recoverable Investment
Land and Site Improvements $200,000
Working Capital 467.000
Total Recoverable Investment $667,000
Total Capital Requirement at 1,000 TPD Capacity $12,784,000
Total Capital Requirement at:
250 TPD Capacity $ 4,370,000
500 TPD Capacity $ 7,470,000
2,000 TPD Capacity $21,850,000
34
-------
TABLE 11
ANNUAL OPERATING COSTS FOR INCINERATION WITH STEAM AND RESIDUE RECOVERY
(300,000 TPY Raw Waste Input)
Annual Costs Total
Operating Costs $1,869,000
Fixed Costs 240,000
Capital Charges
Amortized Investment $ 365,000
Fixed Investment 1,001,000
Recoverable Investment 33.000
Total Capital Charees $1^399^000
Total Annual Cost of Operation $3,508,000
Value of Recovered Resources
Steam $1,000,000
Ferrous Metals 127,000
Nonferrous Metals 240,000
Glass 168,000
Cross Value of Recovered Resources $1.535.000
Net Annual Cost of Operation $1,973,000
Effect of System Capacity on Operating Costs
250 TPD 500 TPD 1.000 TPD
Per Ton of
Waste Input
$ 6.23
0.80
$ 4.66
$11.69
$ 6.57
2.000 TPD
Total Annual Cost $1,200,000 $2,050,000 $3,508,000 $6,000,000
Resource Value 384.000 768.000 1.535.000 3.070.000
Net Annual Cost $ 816,000 $1,282,000 $1,973,000 $2,930,000
Net Cost Per Ton $™'** $8'55 $6'57 $4'88
Net Gain Over Con- ($0.03) $0.43 $1.11 $1.77
ventional Incinera-
tion Per Input Ton
35
-------
3.2.5 Incineration with electrical generation. Almost any process
that produces waste heat is a potential application for electrical generation.
The model here is an electrical generation package driven by the waste heat
of a conventional incinerator.
The incremental investment required to equip a system for elec-
trical generation is quite high—roughly double the basic investment in
conventional waste incineration. Likewise, operation of a plant with on-
site electrical generation increases overall costs substantially (see
Tables 12 and 13), but income is also quite high vis-a-vis the previous two
resource recovery methods. Net costs range from $13.55 per ton to $7.17
per ton, depending on plant size. Thus, the additional capital committed
to the generating facility actually results in higher net operating costs
than for conventional incineration, at the value for electricity given in
Table 3.
The marketability of electrical energy depends on two critical
conditions. First, there must be a customer--either an industrial complex
or a utility. There are serious system interfacing problems because of the
deliverability question and institutional barriers to overcome. Secondly,
the value of electrical energy varies widely over the nation and thus may
bring a high price in one place and a very low price elsewhere. Few util-
ities are likely to pay as much as $0.01 per kwh; more likely they would
look only at their own fuel costs if negotiating for the purchase of
electricity.
Despite these severe limitations, the recovery of electrical
energy is promising and there may be potential situations where electricity
could be produced economically. This is a relatively inflexible recovery
concept, of course, since the energy must be sold as produced and cannot
be stored.
3.2.6 Pyrolysis. A number of pyrolysis processes are in various
stages of development. These units can produce a variety of products, but
the one chosen for economic analysis was synthetic fuel oil (roughly equiva-
lent to No. 6 fuel oil), along with char. The model was the Garrett Research
and Development system. In addition, glass and ferrous metals can be re-
covered from the waste preparation systems.
Tables 14 and 15 summarize the costs of this pyrolysis system.
The investment requirements for pyrolysis are somewhat higher than conven-
tional incineration but within the same general range. Likewise, operating
costs are also relatively high, running $10.96 per ton at 1,000 TPD. Poten-
tial revenues, however, bring net costs down to the range of $9.28 per ton
to $3.88 per ton over the 250 TPD-2,000 TPD operating conditions.
36
-------
TABLE 12
TOTAL CAPITAL REQUIREMENTS FOR INCINERATION WITH ELECTRIC GENERATION
(1,000 TPD Raw Waste Input Capacity)
Amortized Investment
$ 1,789,000
Engineering, R&D
Plant Startup 291.000
Total Amortized Investment $ 2,080,000
Fixed Investment
Waste Handling, Preparation and Storage $ 1,040,000
Waste Conversion 2,600,000
Resource Recovery Processes 4,650,000
Auxiliary and Support Facilities 6.610.000
Total Fixed Investment $14,900,000
Recoverable Investment
Land and Site Improvements $ 300,000
Working Capital 437.000
Total Recoverable Investment $ 737,000
Total Capital Requirement $17,717,000
Total Capital Requirement at:
250 TPD Capacity $ 5,990,000
500 TPD Capacity $10,300,000
2,000 TPD Capacity $30,500,000
37
-------
TABLE 13
ANNUAL OPERATING COSTS FOR INCINERATION WITH ELECTRIC GENERATION
(300,000 TPY Raw Waste Input)
Annual Costs
Operating Costs
Fixed Costs
Capital Charges
Total
$1,748,000
212,000
Amortized Investment $ 480,000
Fixed Investment 1,415,000
Recoverable 37,000
Total Capital Charges $1.932.000
Total Annual Cost of Operation $3,892,000
Value of Recovered Resources
Electrical Energy
Gross Value of Recovered
Resource
Net Annual Cost of
Operation at 1,000 TPD
$1.200.000
$1.240.000
$2,692,000
Effect of System Capacity on Operating Costs
250 IPD 500 TPD 1.000 TPD
Per Ton of
Waste Input
$ 5.83
0.70
6.44
$12.97
$4.00
$8.97
2.000 TPD
Total Annual Cost $1,316,000 $2,263,000
Resource Value 300.000 600.000
Net Annual Cost $1,016,000 $1,663,000
Net Cost Per Ton $13.55 $11.08
Net Gain Over Con- ($3.18) ($2.10)
ventional Incinera-
tion Per Input Ton .
$3,892,000 $6,700,000
1.200.000 2.400,000
$2,692,000 $4,300,000
$8.97
($1.29)
$7.17
($0.52)
-------
TABLE 14
TOTAL CAPITAL REQUIREMENTS FOR PYROLYSIS PROCESS
(1,000 TPD Raw Waste Input Capacity)
Amortized Investment
Engineering, R&D $ 1,211,000
Plant Startup 289.000
Total Amortized Investment $ 1,500,000
Fixed Investment
Waste Handling, Preparation and Storage $ 1,380,000
Waste Conversion 2,840,000
Resource Recovery Processes 960,000
Auxiliary and Support Facilities 4.920.000
Total Fixed Investment $10,100,000
Recoverable Investment
Land and Site Improvements $ 300,000
Working Capital 434.000
Total Recoverable Investment $ 734,000
Total Capital Requirement $12,334,000
Total Capital Requirement at:
250 TPD Capacity $ 4,170,000
500 TPD Capacity $ 7,170,000
2,000 TPD Capacity $21,200,000
39
-------
TABLE 15
ANNUAL OPERATING COSTS FOR PYROLYSIS PROCESS
(300,000 TFY Raw Waste Input)
Per Ton of
Annual Costs Total Waste Input
Operating Costs $1,734,000 $ 5.78
Fixed Costs 210,000 0.70
Capital Charges
Amortized Investment $ 347,000
Fixed Investment 959,000
Recoverable Investment 37.000 4.48
Total Capital Charges $1.343.000
Total Annual Cost of Operation $3,287,000 $10.96
Value of Recovered Resources
Ferrous Metals $ 245,000
Nonferrous Metals 240,000
Glass 168,000
Synthetic Fuel Oil 1.008.000
Gross Value of Recovered Resources $1.661.000 $ 5.54
Net Annual Cost of Operation 1,626,000 $ 5.42
Effect of System Capacity on Operating Costs
Resource Value
Net Annual Cost
Net Cost Per Ton
Net Gain Over Con-
ventional Incinera-
tion Per Input Ton
250 TPD
$1,111,000
415.000
$ 696,000
$9.28
$1.09
500 TPD
$1,911,000
830.000
$1,081,000
$7.21
$1.77
1,000 TPD
$3,287,000
1.661.000
$1,626,000
$5.42
$2.26
2.000 TPD
$5,650,000
3.322.000
$2,328,000
$3.88
$2.77
40
-------
As may be seen in Table 15, the inorganics contribute significantly to total
resource value, and synthetic fuel oil recovery per se accounts for about
two-thirds of the total value.
On an incremental basis the net gain per ton ranges from $1.09 per
ton to $2.77 per ton against straight incineration in the base comparison.
Return on incremental investment is good—22.3 percent at the 1,000 TPD
level. The economics of pyrolysis show the concept to be one of the most
attractive of the resource recovery concepts examined.
Although the synthetic oils have not yet been tested in commercial
fuel applications, early indications are that these oils can be sold as fuel
oil substitutes. If so, they have a universal market since few locales could
not absorb this type fuel into their industrial sector at prices competitive
with their Btu equivalent fuels. In addition, the oil is storable and trans-
portable, a marked advantage over "perishable" commodities (e.g., heat). The
inorganics are recoverable in a generally salable form, although the inorganic
materials recovery systems are less well developed than the pyrolysis furnace
technology itself.
3.2.7 Composting. The model for the compost concept was patterned
after the mechanical digestion approach of the Fairfield-Hardy process, and
the Hercules system. For this reason, a large capital investment is indicated
because of the size of operation and retention time in the digesting process.
Inorganic material recovery was also included in the economic analysis.
The economics of this compost system analysis are summarized in
Tables 16 and 17. The economy of scale of plant size gives a definite advan-
tage to larger plant sizes, and operating costs decline more rapidly with
increasing plant size than most other concepts. In addition, potential
revenues are high because the yield of the process is also high; i.e.,
much of the incoming waste is converted to salable commodities. Net costs
range from $12.46 per ton at 250 TPD to $4.14 per ton for the 2,000 TPD
operation.
On an incremental basis the net savings per ton of input material
ranges from $1.40 per ton to $2.51 per ton (1,000 and 2,000 TPD). The re-
turn on investment, though, is only marginal in these higher operating
ranges. In the lower ranges (250 TPD and 500 TPD) composting does not
appear to be an attractive alternative to conventional incineration.
41
-------
TABLE 16
TOTAL CAPITAL REQUIREMENTS FOR COMPOSTING PROCESS
(1,000 TPD Raw Waste Input Capacity)
Amortized Investment
Engineering, R&D $ 1,748,000
Plant Startup 153.000
Total Amortized Investment $ 1,901,000
Fixed Investment
Waste Handling, Preparation and Storage $ 1,730,000
Waste Conversion 5,500,000
Resource Recovery Processes 940,000
Auxiliary and Support Facilities 6.400.000
Total Fixed Investment $14,570,000
Recoverable Investment
Land and Site Improvements $ 400,000
Working Capital 229.000
Total Recoverable Investment $ 629,000
Total Capital Requirement $17,100,000
Total Capital Requirement at:
250 TPD Capacity $ 6,940,000
500 TPD Capacity $10,900,000
2,000 TPD Capacity $26,850,000
42
-------
TABLE 17
ANNUAL OPERATING COSTS FOR COMPOSTING PROCESS
(300,000 TPY Raw Waste Input)
Per Ton of
Annual Costs Total Waste Input
Operating Costs $ 915,000 $3.05
Fixed Costs 217,000 0.72
Capital Charges
Amortized Investment $ 439,000
Fixed Investment 1,385,000
Recoverable Investment 31.000
Total Capital Charges $1.855.000 6.19
Total Annual Cost of Operation $2,987,000 $9.96
Value of Recovered Resources
Humus $ 450,000
Ferrous Metals 245,000
Nonferrous Metals 240,000
Glass 168.000
Gross Value of Recovered Resources $1.103.000 $3.68
Net Annual Cost of Operation $1,884,000 $6.28
Effect of System Capacity on Disposal Costs
250 TPD 500 TPD 1.000 TPD 2.000 TPD
Total Annual Cost $1,211,000 $1,902,000 $2,987,000 $4,699,000
Resource Value 276.000 552.000 1.103.000 2.206.000
Net Annual Cost
Net Cost Per Ton
Net Gain Over Con-
ventional Incinera-
tion Per Input Ton
43
$ 935,000
$12.46
($2.09)
$1,350,000
$9.00
($0.02)
$1,884,000
$6.28
$1.40
$2,484,000
$4.14
$2.51
-------
Marketability of the compost of humus carries the stigma of a
dismal past record. Humus produced by the patented mechanical process is
superior to other humus products made from mixed waste. Nonetheless, the
recent report of poor market and economic outlook by the 4-year TVA study
is an indication that this is a very high risk concept. There is little opti-
mism for the near-term future for humus, although its use in specialized
agriculture, or special conditions and aggressive marketing could eventually
turn the tide.
The inorganics could be directed to market outlets much more
readily than the humus, and appear suited to the same recycling patterns of
other systems that separate the inorganics prior to conversion of the or-
ganic wastes.
3.2.8 Materials recovery. Comprehensive materials recovery can
be accomplished in a wet system such as the Black-Clawson/Fibreclaim unit,
or by means of a dry separation process typified by the Franklin Institute
system. Either way, provisions are made for the recovery of paper, glass,
aluminum, and ferrous metals. The economic data presented here are generally
consistent with both wet and dry separation processes, although no attempt
has been made to tie the data to any specific system.
Investment requirements are in the range of $8,000 to $15,000 per
daily ton (Table 18). Operating costs (Table 19) decline significantly with
increasing plant capacity. With a revenue base of $4.43 per ton of input
material this concept shows net costs ranging from $9.08 per ton at 250 TPD
to $3.16 at 2,000 TPD. Thus, at 2,000 TPD the materials recovery systems
may become competitive with sanitary landfill.
On an incremental basis, materials recovery systems show a net
gain of $1.29 per ton to $3.49 per ton over incineration. Also, a very good
return on incremental investment is indicated (38.4 percent for a 1,000-TPD
system). Materials recovery appears to be an economically attractive re-
source recovery option.
The economic data assume that the products are fully marketable
at the prices given for each commodity. Once again, market realities dic-
tate comment on this condition.
The quality of the fiber recovered is consistent with the grades
of waste paper used in construction papers (e.g., roofing felt and insula-
tion) and also in combination paperboard filler grades (e.g., cereal cartons,
soap boxes). These paper grades currently consume far more waste paper than
any other uses. However, their share of the market is declining as virgin
fiber displaces more each year. In addition, these grades are readily
available through the commercial waste paper dealer system.
44
-------
TABLE 18
TOTAL CAPITAL REQUIREMENTS FOR COMPREHENSIVE MATERIALS RECOVERY PROCESS
(1,000 TPD Raw Waste Input Capacity)
Amortized Investment
Engineering, R&D $ 1,148,000
Plant Startup 220.000
Total Amortized Investment $1,368,000
Fixed Investment
Waste Handling, Preparation and Storage $ 1,170,000
Waste Conversion 920,000
Resource Recovery Processes 2,810,000
Auxiliary and Support Facilities 4.670.000
Total Fixed Investment $ 9,570,000
Recoverable Investment
Land and Site Improvements $ 300,000
Working Capital 330.000
Total Recoverable Investment $ 630,000
Total Capital Requirement $11,568,000
Total Capital Requirement at:
250 TPD Capacity $ 4,250,000
500 TPD Capacity $ 7,020,000
2,000 TPD Capacity $19,100,000
45
-------
TABLE 19
ANNUAL OPERATING COSTS FOR COMPREHENSIVE MATERIALS RECOVERY PROCESS
(300,000 TPY Raw Waste Input)
Per Ton of
Annual Costs Total Waste Input
Operating Costs $1,320,000 $4.40
Fixed Costs 182,000 0.61
Capital Charges
Amortized Investment $316,000
Fixed Investment 909,000
Recoverable Investment 32.000
Total Capital Charges $1.257.000 4.19
Total Annual Cost of Operation $2,759,000 $9.20
Value of Recovered Resources
Ferrous Metals $245,000
Nonferrous Metals 240,000
Glass 168,000
Paper 675.000
Gross Value of Recovered Resources $1.328.000 $4.43
Net Annual Cost of Operation $1,431,000 $4.77
Effect of System Capacity on Disposal Costs
250 TPD 500 TPD 1.000 TPD 2.000 TPD
Total Annual Cost $1,013,000 $1,671,000 $2,759,000 $4,550,000
Resource Value 332.000 664.000 1.328.000 2.656.000
Net Annual Cost
Net Cost Per Ton
Net Gain Over Con-
ventional Incinera-
tion Per Input Ton
46
$ 681,000
$9.08
$1.29
$1,007,000
$6.72
$2.26
$1,431,000
$4.77
$2.91
$1,894,000
$3.16
$3.49
-------
The recovered fiber could be upgraded to a bleached grade competitive with
groundwood for printing paper. Although the fiber loss would be significant,
the economics of upgrading are unknown now. In general, it appears that re-
covered paper fiber will have limited markets.
The inorganics recovered should find markets more readily than the
fiber, within the grade and quality standards of the output materials. The
glass on a color-sorted basis would be accepted for recycling; the alumi-
num is also readily marketable. In the wet pulping operation there is some
concern that the smashed condition of the ferrous metals would be a factor
in limiting marketability. However, if this is a limit, mechanical shredding
could be applied.
3.2.9 Fuel recovery. One energy recovery approach is the prepara-
tion of mixed waste for use as a fuel in an unconverted form. The model for
this approach is the Horner and Shifrin process now being operated in St. Louis,
where waste is being tested as a supplemental fuel for an electric utility
boiler furnace. (The A. M. Kinney approach is similar.) This process uses
the organic fraction of waste after removal of the ferrous metals and delivers
the prepared fuel to the utility furnace.
The use of existing power plant facilities to burn the fuel gives
the fuel recovery approach a decided advantage in capital investment require-
ments, which are less than any other recovery process for which data were de-
veloped. Only landfill has a lower capital requirement. Investment require-
ments are estimated at $7,577 per daily ton at 1,000 TPD (Table 20). Net
operating costs vary from $5.69 per ton at 250 TPD to $1.62 per ton at 2,000
TPD (Table 21).
This process is competitive with landfill at 1,000 TPD and is
superior to landfill at 2,000 TPD. In fact, the fuel recovery concept has
the most favorable overall economics of any investigated. It is superior
to materials recovery and composting at all levels of operation.
From the standpoint of marketability, fuel recovery also looks
favorable. However, it is a single-market commodity aimed at public util-
ities. When looking at utility fuel requirements, refuse would be a supple-
mentary fuel and would likely not be more than 10 to 15 percent of a utility's
requirement in any one geographic location. There is also a possibility of
use in industrial applications such as cement kilns, where large quantities
of relatively low grade fuel may be used.
There are some institutional barriers to acceptance because the
introduction of a nonconventional fuel would require the utility to adopt
slightly modified operation procedures for a "low Btu value" supplementary
fuel. It appears that the inconvenience of interfacing with a utility could
47
-------
TABLE 20
TOTAL CAPITAL REQUIREMENTS FOR FUEL RECOVERY PROCESS
(1,000 TPD Raw Waste Input Capacity)
Amortized Investment
Engineering, R&D $ 744,000
Plant Startup 133.000
Total Amortized Investment $ 877,000
Fixed Investment
Waste Handling Preparation and Storage $ 2,760,000
Waste Conversion 0
Resource Recovery Processes 0
Auxiliary and Support Facilities 3.440.000
Total Fixed Investment $ 6,200,000
Recoverable Investment
Land and Site Improvements $ 300,000
Working Capital 200.000
Total Recoverable Investment $ 500,000
Total Capital Requirement $ 7,577,000
Total Capital Requirement at:
250 TPD Capacity $ 2,880,000
500 TPD Capacity $ 4,670,000
2,000 TPD Capacity $12,300,000
48
-------
TABLE 21
ANNUAL OPERATING COSTS FOR FUEL RECOVERY PROCESS
(300,000 TPY Raw Waste Input)
Annual Costs Total
«H«>BMMM>
Operating Costs $ 798,000
Fixed Costs 116,000
Capital Charges
Amortized Investment $203,000
Fixed Investment 589,000
Recoverable Investment 25,000
Total Capital Charges $ 817,000
Total Annual Cost of Operation $1,731,000
Value of Recovered Resources
Ferrous Metals $245,000
Fuel 675.000
Gross Value of Recovered Resources $ 920,000
Net Annual Cost of Operation $ 811,000
Effect of System Capacity on Operating Costs
250 TPD 500 TPD 1.000 TPD
Total Annual Cost $657,000 $1,066,000 $1,731,000
Resource Value 230,000 460,000 920,000
Net Annual Cost $427,000 $ 606,000 $ 811,000
Net Cost Per Ton $5.69 $4.04 $2.70
Net Gain Over Con- $4.68 $4.94 $4.98
Per Ton of
Waste Input
$2.66
0.39
2.72
$5.77
$3.07
$2.70
2,000 TPD
$2,810,000
1.840.000
$ 970,000
$1.62
$5.03
ventional Incinera-
tion Per Input Ton
49
-------
be reflected in pricing of the fuel, however. Some other problems would be
likely in some geographic locations--lower fuel costs, unsuitable boiler
configurations, and distance from refuse processing to the customer. These
are local rather than widespread conditions, however. Also, in some areas of
the country, utility fuel values are significantly higher than those used in
this analysis.
3.2.10 Sanitary landfill. The estimated costs for two types of
sanitary landfill operations are summarized: (1) the conventional, close-in
facility (Tables 22 and 23); and (2) a remote facility, located 100 miles
from the municipality which it serves (Tables 24 and 25).
In either case, the sanitary landfill represents a minimal capital
investment. For the close-in facility, land acquisition constitutes the
major investment item (and perhaps a major political undertaking), account-
ing for nearly half of the total capital requirement of $2,472,000 for the
1,000-TPD operation (Table 22).
Because of the nature of the sanitary landfill operation, there is
relatively little economy of scale achieved by increasing the size. Esti-
mated net disposal costs range only from $2.81 per ton at 250 TPD to $2.45
per ton at 2,000 TPD (see Table 23). The close-in sanitary landfill, there-
fore, is still the most economical disposal method for mixed municipal wastes
in volumes of 1,000 TPD or less, and only the fuel recovery concept can com-
pete effectively at 2,000 TPD.
Capital requirements for a remote landfill are only slightly higher
than for the close-in facility. A million-dollar transfer station is largely
offset by the availability of lower cost land at the more distant site
(Table 24).
As shown though, costs are substantially higher for the remote
landfill, primarily because of the cost of transporting wastes over the
100-mile distance (Table 25). Here, net disposal costs are estimated to
run from $6.25 per ton to $5.67 per ton over the 250 TPD to 2,000 TPD scale.
It must be emphasized, however, that differences in land acquisition costs
can easily cause these estimated costs to vary by a factor of two or more.
50
-------
TABLE 22
TOTAL CAPITAL REQUIREMENTS FOR CLOSE-IN SANITARY LANDFILL
(1,000 TPD Raw Waste Input Capacity)
Amortized Investment
Engineering, R&D $ 114,000
Startup 83.000
Total Amortized Investment $ 197,000
Fixed Investment
Site Improvements $ 300,000
Structures 100,000
Equipment 350,000
Miscellaneous 200.000
Total Fixed Investment $ 950,000
Recoverable Investment
Land $1,200,000
Working Capital 125.000
Total Recoverable Investment $1,325,000
Total Capital Requirement $2,472,000
Total Capital Requirement at:
250 TPD Capacity $ 678,000
500 TPD Capacity . $1,295,000
2,000 TPD Capacity $4,725,000
51
-------
TABLE 23
ANNUAL OPERATING COSTS FOR CLOSE-IN SANITARY LANDFILL
(300,000 TPY Raw Waste Input)
Per Ton of
Annual Costs Total Waste Input
Operating Costs $ 500,000 $1.67
Fixed Costs 50,000 0.17
Capital Charges
Amortized Investment $ 46,000
Fixed Investment 108,000
Recoverable Investment 66,OOP
Total Capital Charges $ 220.000 0.73
Total Annual Cost of Operation $ 770,000 $2.57
Effect of System Capacity on Disposal Costs
250 TPD 500 TPD 1.000 TPD 2.000 TPD
Total Annual Cost $211,000 $403,000 $770,000 $1,470,000
Net Cost Per Ton $2.81 $2.69 $2.57 $2.45
52
-------
TABLE 24
TOTAL CAPITAL REQUIREMENTS FOR REMOTE SANITARY LANDFILL
(1,000 TPD Raw Waste Input Capacity)
Amortized Investment
Engineering, R&D $ 234,000
Startup 133.000
Total Amortized Investment $ 367,000
Fixed Investment
Site Improvements $ 300,000
Structures 100,000
Equipment 350,000
Transfer Station 1,000,000
Miscellaneous 200.000
Total Fixed Investment $1,950,000
Recoverable Investment
Land $ 300,000
Working Capital 200,000
Total Recoverable Investment $ 500,000
Total Capital Requirement $2,817,000
Total Capital Requirement at:
250 TPD Capacity $ 772,000
500 TPD Capacity $1,475,000
2,000 TPD Capacity $5,380,000
53
-------
TABLE 25
ANNUAL OPERATING COSTS FOR REMOTE SANITARY LANDFILL
(300,000 TPY Raw Waste Input)
Per Ton of
Annual Costs Total Waste Input
Operating Costs $ 800,000 $2.67
Fixed Costs 68,000 0.23
Capital Charges
Amortized Investment $ 85,000
Fixed Investment 203,000
Recoverable Investment 25.OOP
Total Capital Charges $ 313,000 1.04
Transportation Costs 600.000 2.00
Total Annual Cost of Operation $1,781,000 $5.94
Effect of System Capacity on Disposal Costs
250 TPD 500 TPD 1.000 TPD 2.000 TPD
Total Annual Cost $489,000 $933,000 $1,781,000 $3,400,000
Net Cost Per Ton $6.52 $6.22 $5.94 $5.67
54
-------
3.3 Relative Economics of the Systems
A summary of all system concepts analyzed is given in Table 26 for
a 1,000-TPD operation. Under the stated conditions, the rankings by lowest
net cost are: 1 - fuel recovery; 2 - materials recovery; 3 - pyrolysis;
4 - composting (mechanical); 5 - steam and incinerator residue recovery;
6 - steam recovery; 7 - residue recovery; 8 - electrical energy generation.
However, net costs vary significantly by plant size as indicated
in Figure 1. At 250-TPD plant size, the net costs are high--$5.50 to $13.50
per input ton. As plant capacity rises, the net costs drop significantly.
At 2,000 TPD the net costs vary from $1.60 per ton to $7.20 per ton, repre-
senting a 40 percent to 70 percent reduction in net costs over the small
plant. Differing operating conditions than those assumed here may reflect
significantly on net costs, but the systems generally will maintain their
relative positions. In all cases, the larger plants show the most favorable
net operating cost. (Of course system size must be balanced against collec-
tion and transport costs to consider total costs for any plant installation
contemplated.)
On an incremental cost and benefit basis, the systems vary widely
in their return on investment. Table 27 summarizes the incremental costs,*
savings, and percent return on incremental investment, for each of the
seven concepts compared to conventional incineration for a 1,000-TPD plant.
Incineration accompanied by the recovery of incinerator residues
or steam is moderately attractive, since relatively little additional invest-
ment is required to achieve modest savings in net costs and the return on
investment is in the 8 to 11 percent range.
Energy recovery in the form of electricity shows a negative return
on incremental investment, and would be economically feasible only under
conditions where the value of the electricity was well above $0.006 per kwh.
The materials recovery concept results in high incremental savings
on a low incremental investment, thus yielding a high (38.4 percent) return
on investment. Composting, because of the high capital cost for the mechani-
cal process, produces a low percentage return (5.4 percent) on the incre-
mental investment. The comprehensive materials recovery concept, at lower
incremental costs, provides greater savings and a far higher return on
capital at the 1,000-TPD level.
Incremental costs and investment refer to the dollar difference between a
system operated strictly for waste disposal and one equipped for resource
recovery. A recovery system must return revenues greater than its costs
or it adds to the total cost of operation.
55
-------
Process Concept
TABLE 26
SUMMARY OF RESOURCE RECOVERY PROCESS ECONOMICS!/
Total Net
Annual Resource Annual Net Cost
Investment Cost Value Cost Per Input
($000) ($000) ($000) ($000) Ton ($)
Incineration Only
Incineration and
Residue Recovery
Incineration and
Steam Recovery
Incineration + Steam
and Residue Re-
covery
Incineration and
Electrical Energy
Recovery
Pyrolysis
Composting (mechanical)
Materials Recovery
Fuel Recovery
Sanitary Landfill
(close-in)
Sanitary Landfill
(remote)
9,299 2,303
10,676 2,689
2,472
2,817
0 2,303 7.68
535 2,154 7.18
11,607 3,116 1,000 2,116 7.05
12,784 3,508 1,535 1,973 6.57
17,717
12,334
17,100
11,568
7,577
3,892
3,287
2,987
2,759
1,731
1,200
1,661
1,103
1,328
920
2,692
1,626
1,884
1,431
811
8.97
5.42
6.28
4.77
2.70
770
1,781
770 2.57
1,781 5.94
&l Based on municipally-owned 1000-TPD plant with 20-year economic life,
operating 300 days/year.
Source: Midwest Research Institute.
56
-------
14.00 i-
12.00 -
10.00 -
O
O
u
O
z
i
UJ
Q.
O
8.00 -
Electric Generation
Incineration
B Incineration Only
Incineration + Residue Recovery
Incineration + Steam Recovery
Remote Sanitary Landfill
Incineration + Steam & Residue Recovery
G Composting (Mechanical)
H Pyrolysis
Materials Recovery
Sanitary Landfill
K Fuel Recovery
6.00 -
4.00 -
2.00 -
500 1000
PLANT CAPACITY (TONS/DAY)
2000
Figure 1 - Net Operating Costs Associated with Municipally-Owned
Resource Recovery Processes at Various Plant Capacities
(20 year economic life; 300 days per year operation)
-------
TABLE 27
INCREMENTAL COSTS AND BENEFITS OF RESOURCE RECOVERY PROCESSES
(1,000-TPD Plant)
Process Concept
Incineration and
Residue Recovery
Incineration and
Steam Recovery
Incineration and
Steam + Residue
Recovery
Incineration and
Energy Recovery
Pyrolysis
Composting
Materials Recovery
Fuel Recovery
Incremental
Investment
($000)
1,377
2,308
3,485
Incremental
Savings
($000)
149
187
330
Return on
Incremental
Investment
(7.)
10.8
8.1
9.5
8,418
3,035
7,801
2,269
£/
w
677
419
872
£/
k/
22.3
5.4
38.4
£/
_§/ Compared with conventional waste incineration.
b/ Higher cost than conventional incineration; therefore, there is a
negative incremental return.
£/ Lower capita investment than conventional incineration; therefore, the in-
cremental return is infinite.
Source: Midwest Research Institute.
58
-------
Fuel recovery is a relatively low-cost alternative and is a lower
cost option than conventional incineration. The costs and benefits are such
that this approach shows favorable comparison to landfill and therefore is
the most attractive system from a strictly economic standpoint.
These are the economic comparisons. The question of marketability
considerations was also evaluated to place the economic data in perspective.
3.4 Resource Marketability and Its Effect on Economic Rankings
The product quality of the resource recovery systems is dependent
upon the components of the municipal waste input, and usually the products
compete in the low-quality end of the markets for which they are suitable.
This is a key factor that must be considered in looking at economic viability
of recovery process. However, each product of the resource recovery processes
has a unique relationship to its potential market considering its quality.
For example, electricity can be a relatively valuable energy product in some
situations but has very marginal commercial values in others. Materials re-
covered for recycling are often relatively valuable but only IF a market
exists for the grade and quality of product derived from the recovery system.
The estimated quantity and value of recoverable resources obtainable
from 300,000 tons of mixed municipal wastes was summarized in Table 2. In
order to realistically qualify the various systems in light of the highly
variable and risky market conditions that are likely to prevail for re-
covered products and commodities, the sensitivity of each concept's economics
to changes in these estimated resource values was investigated. In this
analysis, the resource values for each system were varied over a range extend-
ing from 0 to 150 percent of the estimated base commodity values (see
Table 3). The results of this analysis are summarized in Table 28 and are
depicted graphically in Figure 2.
The impact of resource selling prices on the net operating costs
associated with each recovery concept are extremely significant. At the
1,000-TPD, 300,000-TPY level of operation used in the calculations, the
salability of recovered resources over the 0 to 150 percent of base value
range can result in a difference in net operating costs of nearly five times
(in the fuel recovery system, where a high proportion of the waste input
is recovered) to as little as 42 percent in the incinerator residue recovery
system where relatively little value is recovered anyway.
The sensitivity analysis is also a measure of the relative risk
of resource recovery. For example, high capital investment and low realized
income are a serious combination whereas relatively low capital investment
and high realized income make a very favorable risk profile. Said another
way, those systems that have a high investment requirement carry an inherently
59
-------
14.00 i-
LEGEND:
12.00 -
10.00 r
A Incineration + Energy
B Incineration + Residue
C Incineration + Steam
D Compost
E Incineration + Steam & Residue
F Pyro lysis
G Materials Recovery
H Fuel Recovery
I Incineration Only
Sanitary Landfill
K Remote Sanitary Landfill
O
8
o
z
LLJ
8
I—
LU
z
8.00 -
6.00 =
4.00 -
2.00 -
H
0 50 100 150
RESOURCE SELLING PRICES AS PERCENT OF ESTIMATED VALUE
Figure 2 - Sensitivity of Process Economics to Market Value of
Recovered Resources
60
-------
TABLE 28
EFFECT OF RESOURCE VALUE VARIATIONS ON RECOVERY PROCESS ECONOMICS
(1,000-TPD Plant)
Net Operating
Resource Value as Percent
Process Concept
Incineration and Residue
Recovery
Incineration and Steam
Recovery
Incineration + Steam
and Residue- Recovery
Incineration and Energy
Recovery
Pyrolysis - Oil Recovery
Composting
Materials Recovery
Fuel Recovery
Incineration Only
Sanitary Landfill
Remote Sanitary Landfill
150%
6.29
5.39
4.02
6.98
2.65
4.44
2.56
1.17
7.68
2.57
5.94
100%
7.18
7.05
6.57
8.97
5.42
6.28
4.77
2.70
7.68
2.57
5.94
Cost ($/ton)
of Estimated
50%
8.08
8.72
9.13
10.98
8.18
8.12
6.98
4.24
7.68
2.57
5.94
Base Value
0%
8.96
10.38
11.69
12.98
10.96
9.95
9.20
5.77
7.68
2.57
5.94
61
-------
higher risk if the recovered commodities enter volatile markets; the risk
is not so great for low capital investment alternatives. Thus, the fuel re-
covery systems carry a lower risk than say composting. Of course, any
municipality is likely to attempt to "lock up" contractually its recovery
products to minimize revenue uncertainties.
Actual total operating costs would not vary greatly with throughput
volume or period of operation (although per ton costs would vary widely).
The main variable affecting actual operating costs is plant size or through-
put capacity (lower costs per unit as plant size increases). However, the
principal variables that affect economic viability of resource recovery
systems turns on those factors affecting revenues. These are: throughput
tonnage, product value, recovery efficiency and marketable quantity.
Since actual operating costs do not decline significantly with these
variables, an unfavorable situation in any of them leads to both higher unit
costs and lower revenues, and the result could be very high unit costs under
adverse combinations. For instance, a 1,000-TPD plant processing only 500-TPD
and selling only half its normal recovery quantity at half the expected price
would lead to net unit operating costs of more than four times the costs at
full capacity.
This would not be expected to happen in actual practice since each
installation would be carefully planned but the point is that variables
affecting income on a high capital investment and high operating cost systems
are very sensitive. The industrial plant manager knows this well and most
capital intensive industrial operations running above 90 percent capacity
and selling products are profitable whereas if volume or price drops the
operation turns unprofitable very quickly.
The results of this sensitivity analysis serve simply to emphasize
the necessity for a thorough market study prior to undertaking any resource
recovery project. Some of the major considerations to look for in the vari-
ous system concepts are summarized as follows:
3.4.1 Fuel recovery. Minimum capital investment is required and
the waste preparation does not need to be converted to a synthetic "solid"
fuel. The fuel value is relatively low, but costs are lower than other
systems; the operating requirements are less dependent on skilled labor than
other systems. Since waste could be used as a supplemental fuel, there is
minimum disruption to local fuel markets. The limitations are that normally
a single prospective customer is involved—the local utility and local fuel
costs or furnace configurations may prevent use of this recovery process.
In some areas, cement kilns may offer a second market for recovered fuel.
62
-------
3.4.2 Pyrolysis. Oils or gas suitable as commercial fuel have
universal salability and market potential, coupled with strong price stability,
assuming that they perform adequately as a synthetic fuel in existing equip-
ment; the principal inorganics (ferrous metal, aluminum and glass) have good
market potential within geographic and quality limitations.
3.4.3 Materials recovery. In general, materials have the highest
potential product value of any recovery concept. However, the paper fraction
recovered appears to have somewhat limited and uncertain markets, although
there are fair to good potential markets within the geographic and quality
limitations that determine market demand. The inorganics that would be
recovered (ferrous metals, aluminum, and glass) have good market potential
within geographic and quality limitations.
3.4.4 Incineration and residue recovery. The principal inorganics
have good market potential within geographic and quality limitations. How-
ever, the product quality of several of the incinerator residue recovery
fractions indicates that upgrading will be necessary to achieve good market-
ability. The technical and economic requirements for upgrading are under
development, but uncertain. The ferrous fraction as now produced is highly
suitable for copper precipitation use, but not steel making.
3.4.5 Incineration and electrical generation: There is a univer-
sal market for electricity; yet there are substantial institutional barriers
to acceptance. Also, the value of electricity varies widely over the nation
and would, therefore, return an adequate revenue in some installations, but
not in others.
3.4.6 Composting: In general, the yield of usable product per
input ton is the highest for any recovery technique except the energy options.
Humus or compost has a long and dismal past record for marketability. There
are millions of tons of other wastes available that have the technical per-
formance of compost without being converted by process technology; many humus
applications would have to displace other low-value wastes now being utilized.
Market potential for compost is very limited but could improve. The inorgan-
ics have the same potential as indicated in pyrolysis.
3.4.7 Incineration and heat recovery. Steam has universal value
as an energy source. However, there are severe limitations under which it
can be marketed. Favorable conditions could exist in a number of instances
but widespread applications of this sort do not appear practical at this time.
In general, there must be a customer within a short distance of steam genera-
tion who is able to purchase steam at or above the prices used in this analysis.
63
-------
3.5 Municipal Vs Private Ownership
Some of the economic advantages of municipal ownership of waste
disposal or resource recovery processes were cited earlier, where the impact
of ownership on annual capital charge rates was noted (Table 1).
The additional charges that must be applied to the various cate-
gories of invested capital have an important effect on the ultimate net
operating costs of solid waste recovery processes. The effect is most pro-
nounced on processes having relatively high capital requirements.
In addition to incurring out-of-pocket costs for taxes related to
property values, the private owner-operated of a resource recovery process
suffers several other economic disadvantages when compared with a municipal
owner. Tax-free municipal bonds can provide financing for a municipal facil-
ity at interest rates of some 3 percent less than can be obtained by a
private firm either through industrial bonds or conventional borrowing
procedures.
The private firm, too, must satisfy its owners by providing an
adequate return on its invested capital. To obtain a 10 percent net after-
tax return requires that a firm in a typical 50 percent tax bracket earn
a pretax return of 20 percent. If the facility in question is financed by
both internal (equity) and external (debt) capital, the average interest
cost will lie somewhat between the rates applying to these different sources
of funds. For example, if the project were financed 30 percent with equity
capital and 70 percent with debt capital, having 20.0 percent and 8.0 percent
interest rates, respectively, the firm's composite cost of capital would be
11.6 percent. In this case, interest charges applied to various investment
categories would be 11.6 percent for a private owner instead of only 5.0
percent for a municipal owner, resulting in the substantial increases in
fixed costs shown previously in Table 1.
The effect of the additional fixed costs on net operating costs
are summarized in Table 29 for a 1,000-TPD, 300,000-TPY resource recovery
facility. The additional fixed costs that would be incurred by the various
systems because of private ownership range from $480,000 (or $1.60 per ton)
for the low-capital fuel recovery system, to $1,125,000 (or $3.75 per ton)
for the capital-intensive electric generation option. Overall, net operat-
ing costs are increased by 30 to 60 percent by private ownership. Or, stated
another way, a municipality should be able to process its wastes for some
20 to 40 percent less than if it were to contract the operations to a pri-
vate firm, assuming operations of comparable efficiency. However, it should
also be noted that a municipality or other political jurisdiction may be
unable to or may not choose to burden its taxpaying citizens with the debt
loads required for resource recovery and may instead opt for private owner-
ship and higher annual operating costs.
64
-------
TABLE 29
EFFECT OF FACILITY OWNERSHIP ON NET OPERATING COSTSS/
Net Annual
Operating Cost
Under Municipal
Process Concept Ownership
Incineration Only $2,303,000
Incineration and
Residue Recovery 2,154,000
Incineration and
Steam Recovery 2,116,000
Incineration + Steam
and Residue Recovery 1,973,000
Incineration and
Energy Recovery 2,692,000
Pyro lysis 1,626,000
Composting (Mechanical) 1,884,000
Materials Recovery 1,431,000
Fuel Recovery 811,000
Sanitary Landfill
(Close-in) 770,000
Sanitary Landfill
(Remote) 1,781,000
Increase
Additional Net Annual Net Operating Cost Cost For
Fixed Costs Operating Cost ($/ton) Private
Incurred by Under Private Municipal Private Owner
Private Owner^' Ownership Owner Owner ($/ton)
$ 590,000 $2,893,000 7.68 9.64 1.96
676,000 2,830,000 7.18 9.43 2.25
735,000 2,851,000 7.05 9.50 2.45
809,000 2,782,000 6.57 9.27 2.70
1,125,000 3,817,000 8.97 12.72 3.75
781,000 2,407,000 5.42 8.02 2.60
1,088,000 2,972,000 6.28 9.91 3.63
733,000 2,164,000 4.77 7.21 2.44
480,000 1,291,000 2.70 4.30 1.60
141,000 911,000 2.57 3.04 0.47
160,000 1,941,000 5.94 6.47 0.53
Based on 1,000-TPD plant, operated 300 days per year.
b_/ Based on 5 percent interest for municipality and 11.8 percent interest for private owner
(70 percent debt at 8 percent and 30 percent equity at 20 percent) see Table 1.
65
-------
3.6 Resource Supply Contrasted with Plant Economics of Scale
The raw material of resource recovery systems is mixed urban wastes,
and a plant must be sized to serve its raw materials supply. The larger the
plant, the more likely it is to be an economically viable operation. However,
plant size is dictated by the resource base, not by limitations of processing
technology. Thus, the potential plant size is determined by: the population
to be served (city or regional area); the rate and type of waste generation;
and the rate of collection to the central processing point.
The approximate population base required to support various size
plants for: 250 TPD, 500 TPD, 1,000 TPD and 2,000 TPD, was calculated with
a plant size based on the operating rate for 24 hours per day, and 300 days
per year. These data are summarized below.
Annual Input
Plant Size Tonnage Population Base Required for Waste Collection
TPD (300 days/year) (6.04 Ib/capita/dayJQ (4.59 Ib/capita/daylQ
250 75,000 68,200 89,500
500 150,000 136,400 179,000
1,000 300,000 272,800 358,000
2,000 600,000 545,600 716,000
&l Approximate 1970 collection rate (365 days per year average) of urban
wastes from all sources.
t)/ Approximate 1970 collection rate (365 days per year) of urban wastes from
household and commercial sources.
The most efficient economic operation—the largest plant size
possible at full capacity operation shows that for mixed household waste
the smallest population that should be served is about 90,000 persons for
a 250-TPD plant, whereas the largest plant (2,000 TPD) would serve a popu-
lation of 700,000.
There are 90 SMSA's* in the USA with a population base that would
supply waste to a 1,000-TPD plant under the conditions set out above. Of
these, 48 SMSA's would support one or more 2,000-TPD plants; there are more
than 200 areas that could support a 250- or 500-TPD plant.
An SMSA is a census term for Standard Metropolitan Statistical Area which
in general is a county or group of contiguous counties that contain at
least one city of 50,000 inhabitants or more. The SMSA includes counties
that form a socially and economically integrated metropolitan area but
with numerous political jurisdictions (e.g., cities).
66
-------
Of course, using the SMSA as a population base ignores existing
political jurisdiction boundaries. Many areas could be expected to fragment
by political jurisdiction within an SMSA and, therefore, would support a
smaller plant than is indicated by the total population within the SMSA
itself. For example, on a strictly city population basis there are only 12
cities within the top 48 SMSA's in the U.S. above 700,000 population which
would be expected to generate enough waste to supply a 2,000-TPD plant, and
just 26 cities that could supply sufficient input for a 1,000-TPD operation.
There are 34 cities that could justify a 500-TPD operation.
The basis on which a plant is sized must also include a host of
other criteria, such as the logistics and cost of delivering the tonnages
of waste to a central point.
The main point is that in practice few 2,000-TPD plants are justi-
fiable from a strictly plant economic viewpoint, while 500- and 1,000-TPD
plants are the principal sizes to be expected in practice. Thus, the eco-
nomics of these "middle range" plant sizes are most important. On the other
hand, one 2,000-TPD plant processes four times as much waste as a 500-TPD
plant, with something in the order of only 2.5 times as much investment.
Viewed strictly from the standpoint of technology application and economics
of scale, the very largest cities are the most attractive for resource re-
covery plants. And this is where the most pressing solid waste disposal
problems exist today.
ya786
67 * iu.«w«Birpi»in«i«nc6ii»_. 759-551/1053
------- |