vvEPA
Purpose
Section 121 (b) of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA)
mandates the U.S. Environmental Protection Agency (EPA) to
select remedies that "utilize permanent solutions and
alternative technologies or resource recovery technologies to
the maximum extent practicable" and to prefer remedial actions
in which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances,
pollutants, and contaminants as a principal element." The
Engineering Bulletins comprise a series of documents that
summarize the latest information available on selected
treatment and site remediation technologies and related
issues. They provide summaries of and references for the
latest information to help remedial project managers, on-scene
coordinators, contractors, and other site cleanup managers
understand the type of data and site character-istics needed to
evaluate a technology for potential applicability to their
Superfund or other hazardous waste site. Those documents
that describe individual treatment technologies focus on
remedial investigation scoping needs. Addenda will be issued
periodically to update the original bulletins.
Abstract
Composting is an emerging ex situ biological technology
that is potentially applicable to nonvolatile and semivolatile
organic compounds (SVOCs) in soils. It has been applied to
polycyclic aromatic hydrocarbons (PAHs) and explosives. It
has been found to be potentially effective in biodegrading
heavier petroleum hydrocarbons and some pesticides.
Composting is not generally employed to treat heavy metals or
other inorganics, although it may be applicable to inorganic
cyanides.
Composting processes utilize bulking agents, such as wood
chips and straw, to increase the porosity of soil or sediment.
Manure, yard wastes, and food-processing wastes are often
added to increase the amount of nutrients and readily
degradable organic matter. Inorganic fertilizers may be added
to supplement available nutrients. These supplements
encourage growth of indigenous microbial populations capable
of degrading contaminants of concern. Depending on the site-
specific cleanup goals, composting can be used as the sole
treatment technology or in a treatment train.
Composting can be performed in windrows, where material
is put into rows and periodically turned; in aerated static piles,
where perforated pipes within the pile supply aeration; and in
vessels, where material is periodically mixed inside an aerated
containment vessel. Biopiles, which structurally resemble
static pile compost systems with forced aeration, differ from
compost piles in that bulking agents are not added. Biopiles
are outside the scope of this Engineering Bulletin.
The main advantages of composting are its low capital and
operating costs. Because of the low operating costs, it is
economical to continue the composting process for long
periods of time until an endpoint is reached (i.e., when target
levels of contaminants are achieved or toxicity is sufficiently
reduced). Other advantages are the enriched end-product and
simplicity of design. Composting system components are
readily available and can be set up quickly. The main
disadvantages, of composting are that it is a slow process and
consistent temperature control throughout the compost is
difficult to maintain.
As of August 1995, composting was being considered or
implemented as a component of the remedy at two CERCLA,
two Resource Conservation and Recovery Act (RCRA), one
State, two other Federal facility, and three Canadian sites [1,
p. 14][2][3]. Three of these sites have achieved their cleanup
goals. This bulletin provides information on the technology's
applicability, limitations, description, process residuals, site
requirements, regulatory considerations, current or recent
performance data, current status, and a source of further
information.
Technology Applicability
Although composting of yard wastes and municipal
wastewater sludges has been performed for decades,
composting of soils contaminated with hazardous materials is
still an emerging technology. Composting has been
demonstrated to be effective in biodegrading PAHs [2] and
explosives in soils during full-scale applications [4]. Other
studies have indicated that composting is potentially effective
in degrading or transforming petroleum hydro-carbons [1][5]
and pesticides [6, p. 2566] to environ-mentally acceptable or
less mobile compounds.
Despite these promising studies, the ability of composting to
completely degrade man-made organic compounds has not
Printed on Recycled Paper
-------
been fully demonstrated. Although composting systems have
been used to biodegrade hazardous compounds such as
pesticides, PAHs, and explosives, few studies (mostly bench-
scale) have provided mass balance closures or fully
investigated all of the intermediate products, final products, and
by-products of the composting process. In pilot- and field-scale
studies, it is difficult to determine whether the contaminants of
concern were degraded, sorbed to the compost mixture,
volatilized, or incorporated as part of the humic fraction. The
lack of mass balance closure and conclusive evidence of the
fate of contaminants in field-scale applications is not unique to
composting. Many other technologies (both ex situ and in situ)
lack conclusive evidence of contaminant fate in field-scale
applications.
In addition, the use of composting to remediate a specific
site does not ensure that composting will be effective at all
sites or that the treatment efficiency achieved will be
acceptable at other sites. Treatability studies should be
performed to determine the effectiveness of composting at a
given site. Experts at EPA's National Risk Management
Research Laboratory (NRMRL) in Cincinnati, Ohio may be able
to provide guidance during the treatability study and design
phases or provide state-of-the-art facilities for performance of
bench- and pilot-scale treatability studies. General design
information for composting processes can be obtained from
various references [7][8]. It is essential that the general design
principles of conventional composting be followed during
hazardous waste composting, since a healthy microbial
population is required for contaminant degradation [9, p. 62].
It may be necessary to adjust the design, based on treatability
study results, to compensate for the contaminant degradation
rates and soil conditions at a given site.
Advantages of composting over other types of tech-nologies
include relatively low capital and operating costs, simplicity of
operation and design, and readily available components.
Because of the low operating costs, it is economical to
continue the composting process for long periods of time, if
required, to reach the desired endpoint. Another advantage of
composting is that the composted soil is enriched in nutrients
and suitable for re-vegetation. Composting can also be
integrated into a treatment train. Capital costs can be
optimized by tailoring the level of process control to the
contaminant type. For example, static pile composting may be
sufficient for petroleum hydrocarbons, whereas an in-vessel
system may be more appropriate for halogenated SVOCs.
The effectiveness of composting treatment systems on
general contaminant groups is shown in Table 1. For this
document, "effective" means that several of the contamin-ants
listed In a group have been shown to be biodegradable in full-
scale remedial applications. Biodegradability varies widely
among compounds in many groups. Examples of constituents
within contaminant groups are provided in "Technology
Screening Guide for Treatment of CERCLA Soils and Sludges"
[10]. Other contaminants for which composting is applicable
may not be included in these categories. However, many of the
other compounds will biodegrade like contaminants in
these categories. For example, some explosives are
•S
§>
0
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
a
a
a
a
a
T
Table 1
Effectiveness of Composting on General
Contaminant Groups for Soil and Sludges
Contaminant Groups3
Effectiveness*1
1
6
Halogenated volatiles0
Halogenated semivolatilesd'e
Nonhalogenated volatiles0
Nonhalogenated semivolatilesd
PCBsd'e
Pesticides6''
Dioxins/Furans
Organic cyanides
Organic corrosives
a
V
a
T
T
a
T
T
Oxidizers
Reducers
O
D
See the "Technology Screening Guide for CERCLA Soils and Sludges"
for a list of the contaminants in each group.
For this document, "effective" means that several of the contaminants
listed in a group are biodegradable.
While these contaminants may be biodegradable, they would likely be
volatilized before being degraded.
Smaller, less halogenated compounds in this category are better
candidates for composting.
May require an anaerobic/aerobic cycle.
Composting is not recommended for organometallic compounds.
No Expected Effectiveness: Expert opinion is that technology will not
work.
Potential Effectiveness: Expert opinion is that technology will work.
Demonstrated Effectiveness: Successful treatability test at pilot- or field-
scale completed.
chemically similar to corn-pounds in the nonhalogenated SVOC
category; therefore, composting is expected to degrade these
compounds. Information in this table is provided as general
guidance on effectiveness; consultation with technology
experts and site-specific treatability studies are recommended.
Table 1 is based on the current available information or,
if no information is available, professional judgment. The
proven effectiveness of the technology for a particular site
Engineering Bulletin: Composting
-------
or waste does not ensure that composting will be effective
at all sites or that the treatment efficiencies achieved will be
acceptable at other sites, especially when a site is
contaminated by several types of wastes. For the ratings in
Table 1, Demonstrated Effectiveness means that, during
full-scale applications, the technology degraded the parent
compound for several contaminants within that particular
contaminant group. Composting has been demonstrated to
be effective in remediating PAHs and explosives in soils.
Ratings of Potential Effectiveness or No Expected
Effectiveness are based upon the judgement of a panel of
EPA and non-EPA experts. Where Potential Effectiveness is
indicated, the technology is believed capable of successfully
treating several compounds in the contaminant group.
When the technology is not applicable, a No Expected
Effectiveness rating is given. This rating applies primarily to
contaminants that are not biodegradable (e.g., asbestos and
radioactive materials). Experts also believe that composting
is generally not effective for halogenated and nonhalo-
genated volatiles because they will normally volatilize before
they have the opportunity to biodegrade. This does not.
mean that composting cannot be applied to soils that
contain volatile organic compounds (VOCs) and SVOCs if
the VOCs are collected and treated. However, the presence
of VOCs in significant concentrations likely precludes the
use of windrow composting since VOC collection is not
feasible.
Limitations
In general, composting is slower than many other
nonbiological soil remediation technologies, but its
application can be flexible and cost-effective. Batch
remediation times ranging from 2 to 20 weeks are common
for composting hazardous wastes. However, the compost
may require several years of maturation or storage to
decrease the residual concentrations of contaminants to
environmentally acceptable levels.
Site- and contaminant-specific factors impacting contam-
inant availability and microbial activity may limit the
application of composting. Site-specific factors include soil
characteristics, climatic conditions, and location of con-
tamination at the site. Contaminant-specific factors include
volatility, biotoxicity, polarity, and chemical structure.
Site-Specific Factors
While the soil characteristics discussed in the following
paragraphs potentially limit the applicability of composting
to some sites, it is important to note that all of these soil
characteristics can be modified. A discussion of some of
the techniques used to modify soil characteristics is
presented in the Technology Description section. It should
also be noted that other ex situ technologies are affected by
these same soil characteristics.
Soil characteristics that may affect the applicability of
composting include particle size distribution, moisture
content, pH, and nutrient levels. Particle size can impact
mixing, moisture holding capacity, oxygen transfer rates,
and contaminant adsorption and availability. Wet clays can
be difficult to mix with amendments, and lumping can
result. Lumping can limit oxygen transfer rates and
contaminant availability, resulting in incomplete treatment.
Clays and humic materials have high moisture holding
capacities; excessive moisture can fill void spaces and limit
oxygen transfer. Sandy soils have low moisture holding
capacity and may drain quickly, resulting in drying of upper
regions of compost piles. Localized drying can reduce
microbial metabolism, resulting in incomplete contaminant
degradation. Because of increased surface area and soil
particle charges, contaminant sorptinn can be problematic
in clayey soils and soils with high humic content [11, p. 33].
If contaminants are strongly sorbed onto soil particles,
contaminant desorption rates are reduced. The remediation
rate may be limited by the slow kinetics of contaminant
desorption rather than biodegradation.
Soil pH, moisture content, nutrient deficiencies, temper-
ature, and oxygen concentration can affect the diversity and
activity of the microbial population and suppress specific
contaminant degraders. If the process is poorly controlled
so that wide variations exist, inconsistent or undesirable
results will be obtained due to fluctuations in biological
activity. Oxygen deficiencies will promote anaerobic
microorganisms and inhibit aerobic respiration, the
predominant form of microbial metabolism in composting.
The biodegradation of chemical contaminants that are
recalcitrant to aerobic decomposition (e.g., polychlorinated
organic compounds) may be initiated or occur more readily
under anaerobic conditions. Pockets of anoxic conditions
may exist within agglomerates and aggregates in compost
piles even under bulk aerobic conditions. Complete
breakdown or mineralization of substituted aromatics is not
common under anaerobic conditions.
The location of contaminants at a site will affect the
feasibility and costs of implementing composting. Since
composting is an ex situ technology, it is limited to fairly
shallow soils (e.g., less than SO feet deep) that can be
excavated economically. As with other ex situ tech-
nologies, composting is not practical for use when
contaminants are located under buildings or other
structures.
Additional site-specific limitations, such as accessibility
and odor control problems, are discussed in the Site
Requirements section of this bulletin.
Contaminant-Specific Factors
Contaminant volatility will limit the residence time of
chemicals in composting systems. These systems frequent-
ly achieve temperatures in excess of 40 °C within the first
week of operation, and may operate for several months at
temperatures in excess of 60°C. At these elevated temper-
atures, a large portion of any VOCs is volatilized before
significant biodegradation can occur. Soils that contain
both VOCs and less volatile contaminants can be
composted, and volatilized contaminants can be collected
Engineering Bulletin: Composting
-------
from the air. However, even though many VOCs are
biodegradable, composting is not be recommended for soils
containing primarily VOCs. At elevated temperatures,
certain VOCs can pose threats of fire or explosion in
enclosed systems unless proper controls are installed.
As with any biological treatment, biotoxicitv of certain
contaminants may limit the applicability of composting.
Treatability studies will be required to determine if the
contaminant types or concentrations inhibit microbial
growth or activity in composting systems.
Polarity and chemical structure impact the solubility and
bioavailability of contaminants. Types and positions of
substitution groups can affect biodegradation rates and
metabolic pathways. A detailed discussion of this subject
is beyond the scope of this document. Consultation with
bioremediation experts and performance of site-specific
treatability studies are recommended.
Technology Description
Composting can be distinguished from other forms of
biological remediation by the use of bulking agents that
Increase soil porosity and, in some cases, provide a readily
available carbon source. Frequently, other easily-degradable
carbon sources are added to sustain microorganisms
capable of degrading hazardous waste constituents
associated with a solid medium, such as soil. Composting
biodegrades organic matter utilizing solid-, liquid-, and gas-
phase processes. The solid phase provides physical support
for biofilm growth, a source of organic and inorganic
nutrients, a sink for metabolic products, and thermal
Insulation [12, p. 2]. The liquid phase, which is a surficial
layer on the solid, provides a matrix for exchange of gases,
nutrients, and metabolic products. The gas phase delivers
oxygen and provides a sink for gaseous metabolic products,
such as carbon dioxide and ammonia. The gas phase also
serves as the primary heat sink through evaporative cooling.
Figure 1 is a schematic representation of the composting
process. Pretreatment for composting consists of
excavating the contaminated material and screening or
shredding the large debris to a smaller size. If the
contaminant is present as free product, it should be
removed before composting is initiated. Amendments such
Bulking Agents/
lie Material
Excavate
and
Preprocess
Soil
w
\
i
•^ r\ev»yuieu ouiiMiiy
Water Agents
; A
^ * <->UI 1 ipubt p
* ^
^ Composted
Material
Seeded Oxygen N/P
^ ... i •+
as bulking agents and/or organic material are then added to
the soil. Microorganisms can be added, although indigenous
organisms are normally sufficient to achieve the desired
biodegradation. The material is then left to compost in
vessels, windrows, or static piles. Oxygen is added to the
compost by forced aeration in static piles or in-vessel
systems, or by mixing and passive diffusion in windrows.
Water can be added to the compost to achieve optimum
moisture content, and nitrogen (N) and phosphorus (P) can
be added if the compost is nutrient-poor, which is often the
case. After the desired composting end-point is reached,
bulking agents can sometimes be separated from composted
material and recycled, and composted material can be used
to inoculate more soil. Easily degradable bulking agents will
not be separable. Finally, composted material can be put
into piles for additional curing, treated by another
technology as part of a treatment train, or relocated to
onsite or off site disposal areas.
The major form of microbial metabolism in the
composting process is aerobic respiration, although mass
transfer limitations within the composting mass may cause
anaerobic zones. The anaerobic zones of compost systems
may facilitate degradation of compounds, such as DDT and
dieldrin, making them more susceptible to aerobic
decomposition [13, p. 32]. However, since there is little
information available regarding anaerobic composting, this
bulletin focuses on aerobic processes.
The composting process is essentially microbiological,
mediated by microbial populations that are classified as
mesophiles orthermophiles. Mesophilic microbes are those
with an optimum temperature range of 25° to 40 °C;
thermophilic microbes have an optimum temperature range
of 40° to 60°C[14, p.1].
During composting, there are four major microbiological
phases that are identified by temperature. The optimal
degradation temperature is contaminant-specific. Tempera-
ture ranges cited for mesophiles and thermophiles vary
between references, resulting in a small overlap in these
phases. In static pile and in-vessel composting, air flow
rates can be used to influence temperature. Air flow is
often intermittent, and the inflow point is sometimes varied
to prevent the bed from drying out at the point of air entry.
T Treatment Train
> Curing Stage
* Disposal
Microbes'
•> Indicates Optional Steps
Figure 1. Schematic of Composting Process.
Engineering Bulletin: Composting
-------
The first of the four phases is the mesophilic stage, in
which temperatures range from 8° to 45°C. The greatest
microbial diversity exists in this stage. The second phase is
the thermophilic stage, in which temperatures are above
40°C [14, p. 229J[15, p. 1]. Certain degraders will be
inhibited by thermophilic temperatures. Few thermophilic
microorganisms have been identified that are capable of
degrading or mineralizing man-made compounds. The role
of the thermophilic phase of the composting process
continues to be investigated. The third phase is the cooling
stage, in which there is a microbial recolonization including
mesophilic fungi, the spores of which withstood the
thermophilic stage. The fourth and final phase is the
maturation phase, in which most of the digestible organic
material has been consumed, and the composted material
becomes stable [14, p. 228]. Recalcitrant compounds will
continue to be degraded by organisms such as fungi during
the fourth phase. The maturation phase should be extended
until concentrations of recalcitrant compounds are below
target levels.
The optimum moisture content for composting varies
depending on the water-holding capacity and porosity of the
compost mixture and the type of composting technology
being implemented, but a moisture content of less than 40
percent (by weight) frequently inhibits bacterial activity [13,
p. 32]. For composting of soils mixed with amendments,
the optimum moisture content is typically 40 to 60 percent
(by weight). Periodic addition of water is required for nearly
all composting operations; however, excessive water
content slows down gas diffusion and may lead to the
establishment of anaerobic conditions and associated odor
control problems. Excessive water addition can also lead to
formation of leachate that must be collected and managed.
Adequate oxygen supply to the microbes is essential for
composting. Oxygen can be supplied within the compost
using forced air (i.e., a blower) or passive diffusion (aided
by turning over or agitating the material). However, these
oxygen addition techniques will be inadequate unless the
compost mixture has adequate porosity, which is defined as
the ratio of the volume of voids to the total volume of soil.
A porosity of 0.30 to 0.35 is optimum for composting
processes. Other optimum operating conditions for
composting are a pH of 6 to 8 and an available carbon to
nitrogen to phosphorus (C:N:P) ratio of 100:4:1 by weight
[16, p. 249][17, p. 57].
A large portion of the compost mixture must contain
readily biodegradable solid organic material. Such
substances include vegetation and food processing wastes
(e.g., sawdust, grass clippings, alfalfa, potato peels, apple
peels, etc.), which are organic materials rich in carbon. In
most cases, additional inorganic nutrients (primarily nitrogen
and phosphorus) are also needed to provide optimal
conditions for microbial metabolism. This need can be
addressed by the addition of fertilizer or manure [18, p. 92].
Grass clippings and alfalfa can play a dual role, as they are
rich in carbon and nitrogen and can be added as a nitrogen
amendment to carbon-rich substrates. The organic material
may also increase the porosity of the compost mixture.
When the mixture of soil and organic material has a low
porosity, a bulking agent should be added [19, p. 2332],
Ideal bulking agents provide ample porosity under all
moisture conditions, are absorbent, and resist compaction.
The bulking agent may be a slowly-degrading substance
that serves as a supplemental carbon source, or it may be
a nondegrading substance that can be easily recovered from
the composted wastes and recycled [13, p. 32]. Suitable
bulking agents include fibrous vegetation (e.g., straw),
wood chips or bark, corn cobs, rice hulls, and peanut shells.
Soil-to-bulking agent ratios of between 50:50 and 70:30
have been frequently applied. Recyclable bulking agents,
such as wood chips, may be recovered by screening the
composted wastes.
Bioaugmentation (the addition of microorganisms) is
occasionally employed in composting processes, but its
utility has yet to be proven and is currently an issue of
controversy. Bioaugmentation may be inappropriate
because introduced cultures may lack the microbial diversity
that is an important factor in decomposing contaminant
mixtures in natural systems. Partial return of composted
product to fresh compost piles can provide beneficial
inoculum.
Composting can be divided into three categories: in-
vessel composting, windrow composting, and static pile
composting. The remainder of this section describes these
three categories. Biopiles, which do not utilize bulking
agents, are also briefly described to differentiate them from
composting.
/n-Vessel Composting
When performing in-vessel composting, material is
placed inside a large containment vessel equipped with a
temperature-controlled aeration system. In-vessel compost-
ing is conducted in partially or totally enclosed vessels;
however, the curing phase may take place in a static pile to
reduce the residence time in the vessel. In-vessel systems
can also be equipped with a mechanism that will periodically
mix or agitate the composting material [18, p. 94].
The advantages of in-vessel composting include greater
process control than in other types of composting and
reduced space requirements. In-vessel composting may
also be used for sequential treatments, such as anaerobic-
aerobic phases that may promote the biodegradation of
highly chlorinated organics. Use of a system in which the
vessels are totally enclosed is desirable when highly toxic
substances are present, or when off-gas collection is
desired [18, p. 94]. This type of system controls odors
better than either windrow or static pile composting [20, p.
56]. Gas exiting the reactor can be continuously monitored
for oxygen, carbon dioxide, methane, and humidity. The
gas stream can be passed through air pollution control
equipment. Computers can monitor the system, collect
data, and adjust parameters, which is useful for composting
research and treatability studies and to optimize degradation
rates. Disadvantages of in-vessel composting include higher
capital and operating costs and a longer lead time for. setup
Engineering Bulletin: Composting
-------
than in other types of composting. Since the system is
automated, mechanical breakdown can occur. Fires can
occur during in-vessel composting of mixtures composed
primarily of organic materials, but are not likely during
composting of soil mixtures.
Windrow Composting
In windrow composting, the material to be composted is
formed into long parallel rows, which are approximately 1.4
to 1.7 meters (m) in height [7, p. 45]. Some type of
containment, such as a plastic liner or a concrete pad, is
typically required below the windrows. The rows, which
may be watered occasionally, are periodically turned to
promote aeration [18, p. 93]. Full-scale windrow
composting uses specialized machines called windrow
turners, commercially-available vehicles, designed to turn
and shape windrows.
The advantages of windrow composting over other types
of composting are low capital and operating costs, thorough
blending, ease of adding water and nutrients when the
windrow is broken down, and greater volumes of material
treated. Disadvantages of windrows include large space
requirements, difficulty in controlling fugitive emissions, and
the fact that, if not covered or sheltered, windrows may be
exposed to excessive rainfall and prohibitively low
temperatures. The system may not be desirable if tight
process control is needed. Windrow temperature is a
complex function of feed material, pile depth, moisture
content, nutrient content, ambient air conditions, and
turning frequency. Once a windrow is constructed and the
bulking agent added, the range of temperature is relatively
fixed. Consequently, other composting technologies maybe
more appropriate than windrow composting when
temperature control is important.
Static Pile Composting
In aerated static pile composting, the material to be
biodegraded is mixed with an appropriate bulking agent and
formed into a pile, which may be watered occasionally.
Because the piles have a built-in aeration system that
provides oxygen and removes heat, no turning is required.
The aeration system generally consists of a series of
perforated pipes located underneath or inside the pile [18, p.
93]. Airflow can be upward or downward through the pile
and can be driven by positive pressure or a vacuum.
In aerated static pile composting, fairly precise
temperature control is possible by manipulating the design
and operating parameters of the aeration system [20, p.
56]. Aerated static piles allow better control of temperature
and oxygen concentration than windrows, but less than in-
vessel applications. Air can be drawn through the pile and
the ventilation system can be interfaced with a biofilter for
trapping and removing odors and VOCs. The cost of
aerated static piles falls between windrows and in-vessel
systems. Like windrows, static piles may be affected by
extreme environmental temperature changes and heavy
rainfall. Unlike windrows or in-vessel systems, static piles
are not mixed periodically to redistribute the material.
A summary of the relative advantages and disadvantages
of each of the types of composting is presented in Table 2.
Although these qualitative rankings generally apply, site
conditions vary, which may render them not applicable in
certain situations.
Biopiles
Biopiles are outside the scope of this bulletin. Biopiles
are a specialized approach to ex situ bioremediation in
which bulking agents are not used. Contaminated soil is
blended with nutrients and placed in the biopile to enhance
contaminant degradation by soil-borne microorganisms.
Exogenous microorganisms may be added to a biopile.
Biopiles structurally resemble static pile compost systems
with forced aeration, air usually being drawn through the
pile by a vacuum. Depending on the types of soil
contaminants, the operator may establish conditions in the
biopile reactor to favor either anaerobic or aerobic
microorganisms. Biopiles normally produce less heat than
compost piles since less organic substrate is added,
although significant aerobic microbial activity will produce
some heat.
Table 2
Summary of Characteristics of the Different Types of Composting
Parameter
Temperature Control
Fugitive Emission Control
Sequential Treatment
Cost
Area Requirements
In-Vessel
Easy
Easy
Easy
High
Moderate
Windrow
Difficult
Difficult
Difficult
Low
High
Static Pile
Moderate
Moderate
Moderate
Medium
High
Engineering Bulletin: Composting
-------
Process Residuals
Although the majority of wastes requiring disposal are
generated as part of pre- and post-treatment activities,
process residuals arising directly from composting may also
be generated. Potential process residuals include off-gases
from the composting process, excess water (from moisture
addition or, in open systems, from rainfall), and the final
compost mixture (including any undegraded supplements).
These residuals may contain undegraded parent contam-
inants, partially degraded contaminants, or metabolic by-
products of the degradation process. The following
paragraphs discuss specif ic types of process residuals, their
control, and their impact on disposal requirements.
Air emissions may be a concern, depending on several
factors. The volatility of the parent substances, as well as
potential biotransformation products, must be considered.
If a mechanical aeration system is utilized, the manner in
which it is operated (vacuum or forced aeration) can impact
emissions [18, p. 94]. Vacuum systems can be vented
through biofilters or carbon adsorption systems to remove
VOCs. Totally enclosed, in-vessel composting offers easier
control of air emissions. If air emissions are a problem, an
emission control and treatment system will be required.
Composting systems may produce odor problems,
especially when anaerobic conditions dominate. Odors can
be minimized by making operational adjustments, such as
increasing porosity, additional mixing, or addition of oxygen.
If odor control is necessary, many of the measures recom-
mended for control of air emissions will also reduce odors.
Excessive watering or precipitation (in open systems) will
produce leachate. Any liquids exiting the composting
process may contain soluble contaminants and must be
collected and recycled or treated.
Contaminants may sorb onto bulking agents used in the
composting process. Recyclable bulking agents should be
removed and reused until site remediation is complete.
They may require treatment when the composting process
is complete.
Ultimately, biological technologies seek to convert
hazardous contaminants into relatively innocuous end-
products. If mineralization is achieved, the ultimate end-
products will be carbon dioxide, water, and inorganic salts.
However, a number of contaminant-specific factors may
cause partial degradation to an intermediate product.
Identification of intermediate products may not be practical
or cost-effective. Instead, the toxicity of the composted
material can be measured to ensure detoxification. If
detoxification is not sufficient, further treatment of the
composted material may be necessary.
The disappearance of the parent compound must also be
measured. Some contaminants are not amenable to bio-
logical degradation. For contaminants that are biodegrad-
able, microbes degrade only the biologically available
fraction of the contamination. In addition, the sorption of
contaminants onto the compost mixture may become a rate-
limiting factor for the biodegradation process, since the
desorption rates are often extremely slow.
Because composting involves the addition of
amendments and bulking agents, the volume of the finished
product is typically greater than the volume of untreated
material. If composting does not adequately degrade the
contaminants of concern, it increases the volume of waste
requiring treatment or disposal.
Site Requirements
Composting is best suited for onsite treatment and is
best applied at sites which are accessible to heavy
equipment and have sufficient space for onsite operations.
In general, significantly less area is required for mixing
equipment than for the compost piles or vessels. However,
space requirements increase as the complexity of the
various pre- and post-treatment systems increases.
Compost piles should be constructed on a liner or bermed
concrete or asphalt pad, and provisions should be made for
leachate collection and treatment. Asphalt compost pads
are easier and cheaper to construct than concrete pads;
however, they are more permeable. A cover may be
necessary to avoid agglomeration of soils due to rainfall and
to prevent wind erosion. Even if agglomeration is not a
problem, a cover may be more cost-effective than collecting
and treating leachate caused by heavy rainfall. If periods of
heavy rainfall or extremely cold conditions are expected, a
cover may be required or the composting system may be
housed in a ventilated building.
Regulatory Considerations and
Response Actions
Federal mandates can have a significant impact on the
application of composting technologies. RCRA Land
Disposal Restrictions (LDRs) that require treatment of
wastes to Best Demonstrated Available Technology (BDAT)
levels prior to land disposal are considered to be Applicable
or Relevant and Appropriate Requirements (ARARs) for
CERCLA response actions. Composting can produce a
treated waste that meets treatment levels set by BDAT, but
not in all cases. The ability to meet required treatment
levels depends. on the specific waste constituents and the
waste matrix. In cases where composting does not meet
these levels, it still may be selected in certain situations for
use at the site if a treatability variance establishing
alternative treatment levels is obtained. Treatability
variances are justified for handling complex soil and debris
matrices. The following guides describe when and how to
seek a treatability variance for soil and debris: Superfund
LDR Guide #6A, "Obtaining a Soil and Debris Treatability
Variance for Remedial Actions" (OSWER Directive
9347.06FS, September 1990) [21], and Superfund LDR
Guide #6B, "Obtaining a Soil and Debris Treatability
Variance for Removal Actions" (OSWER Directive 9347.
06BFS, September 1 990) [22].
Engineering Bulletin: Composting
-------
When determining performance relative to ARARs and
BOAT, emphasis should be placed on assessing the risk
presented by a bioremediation technology. As part of this
effort, risk assessment schemes, major metabolic pathways
of selected hazardous pollutants, human health protocols for
metabolite and pathogenicity tests, and fate protocols and
issues for microorganisms and metabolites must be
assessed [23]. Baseline and final toxicity testing can be an
important tool in verifying achievement of cleanup goals
established using ecological risk assessment.
Performance Data
Composting has been used to remediate three sites;
however, reports summarizing performance data were only
available from one of these sites. This section presents
performance data for this site and four composting
demonstrations. The results presented are based on
available information. It was beyond the scope of this
project to review quality assurance data and validate
analytical results. Therefore, the quality of these data
cannot be determined. As with most large-scale studies
(including other technologies) mass balance closure of
targeted pollutants has not been provided for these case
studies. Therefore, it is difficult to determine if contaminant
loss is attributable to degradation, sorption to the compost
mixture, or volatilization.
Indiana Woodtreating Corporation Site
Aerated static pile composting was used as a remedy at
the Indiana Woodtreating Corporation Site in Bloomington,
Indiana. Soils were contaminated with creosote to depths
ranging from the surface to 12 feet below the surface.
Total PAH (TPAH) concentrations in the soil were
approximately 20,410 mg/kg. Action levels for the site
were 500 mg/kg TPAHs and 100 mg/kg for each of the
carcinogenic PAHs. Contaminated soil was excavated,
dried when necessary, screened to remove rocks larger than
3 inches in diameter, and mixed with amendments. The
optimum composting mixture for every 100 tons of soil
was determined in treatability tests to be 5 rolls of straw, 5
bales of horse manure, 20O pounds of urea fertilizer (37-0-
0), and 100 pounds of ammonium nitrate fertilizer (34-0-0).
The weights of the straw and manure were not provided in
the report. Rototillers and tractors were used to mix the
piles.
The final design of the compost piles consisted of 4-inch
perforated and corrugated polyvinyl chloride (PVC) piping for
aeration and 3/4-inch PVC piping for watering. Dimensions
of piles were not given, but 22,000 tons of contaminated
soil were treated in nine piles. Analytical results from
samples collected biweekly indicated that PAH
concentrations decreased exponentially and the microbial
population was high. Compost piles were maintained for
about 1 year, at which time contaminant concentrations in
the piles were consistently below the action levels for the
site. The composted material was then landfarmed for
approximately 1 additional year in a 2-foot-thick layer.
TPAH concentrations, after the year of landfarming was
complete, fell below 100 mg/kg in all landfarm areas [2].
Umatilla Depot Activity Site — Windrow
A 40-day, full-scale demonstration of windrow
composting was performed at the Umatilla Depot Activity
Site. The windrow was turned once each day, and its
internal temperature was recorded before and after turning.
Although the turning process typically reduced the internal
temperature by at least a few degrees, the internal
temperature achieved was between 40° and 55°C from
Day 6 through Day 24. The composting mixture consisted
of 30.0 percent soil, 24.4 percent manure, 10.0 percent
vegetable waste, and 35.6 percent alfalfa/sawdust, by
volume. Table 3 lists the contaminant concentrations and
reductions on various days of the study. The contaminant
concentrations for Day 0 describe the compost mixture
shortly after it was prepared (rather than the soil before the
amendments were added) [24]. Concentrations of four
2,4,6-trinitrotoluene (TNT) intermediate products were also
measured. Two of these were below detection limits on
Day 0, and the other two decreased as the study
progressed [4].
Toxicological studies were performed on leachate
prepared from the compost mixture using EPA Method
1312: Synthetic Precipitation Leaching Procedure (SPLP)
[25]. The aquatic toxicity tests measured the mortality and
inhibition of reproduction of the fresh water crustacean
Ceriodaphnia dubia. Results indicate that the compost
leachate concentration (as a percent of full-strength)
required to kill 50 percent of the test organisms in 7 days
(LC50) increased from 4.0 percent on Day 1 to 47.5 percent
on Day 40. The concentration of compost leachate required
to lower mean reproduction to 15 offspring per female in 7
days (SR15) increased from 1.9 percent on Day 1 to 14.2
percent on Day 40. The study concluded that biotrans-
formation of the explosives to less toxic compounds had
occurred [24, p. 8-1][26, p. 123].
Umatilla Depot Activity Site — In-Vessel
A pilot-scale demonstration was performed at the
Umatilla Depot Activity site using a 7-cubic-yard,
mechanically-agitated, in-vessel composting system to
remediate soil contaminated with explosives [TNT;
hexahydro-1,3,5-trinitro-1,3,4-triazine (RDX); and octa-
hydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)]. The
temperature of the compost mixture was kept at or below
55°C using forced aeration, and the moisture content was
maintained between 45 and 50 percent. Three different
amendment mixtures were used. Mix A contained (by
volume) 30 percent sawdust, 15 percent apple pomace, 20
percent chicken manure, and 35 percent chopped potato.
Mix B consisted of 50 percent horse manure/straw, 10
percent buffalo manure, 32 percent alfalfa, and 8 percent
horse feed. Mix C contained 22 percent sawdust, 6 percent
apple pomace, 17 percent chopped potato, 22 percent
alfalfa, and 33 percent cow manure. Table 4 summarizes
the amount of soil and amendment mix used, percent
disappearance of contaminants, and the duration of each of
four studies. The majority of the contaminants that
disappeared did so within the first 10 days. The
pretreatment basis for the contaminant disappearance
8
Engineering Bulletin: Composting
-------
Table 3
Contaminant Reductions [24]
Percent Disappearance
Day
0
5
10
15
20
40
TNT
mg/kg
1,563
101
23
19
11
4
RDX
mg/kg
953
1,124
623
88
5
2
HMX
mg/kg
156
158
119
118
2
5
TNT
0.0
93.5
98.5
98.8
99.3
99.7
RDX
0.0
0.0
34.6
91.7
99.5
99.8
HMX
0.0
0.0
23.7
24.4
98.7
96.8
Table 4
Percent Disappearance of Explosives [4][27]
Percent Disappearance
Soil in Compost,
Percent
10
10
25
40
Amendment Mix
A
B
C
C
TNT
97
99
99
97
RDX
90
99
97
18
HMX
29
95
68
0
Duration of
Study
44 days
43 days
44 days
45 days
calculations (concentrations in unamended soil or compost
mixture) is not specified, so it is not clear whether a portion
of the reported disappearances is due to dilution of soil by
amendments [27].
Louisiana Army Ammunitions Plant (LAAP)
A field-scale demonstration was conducted at the
Louisiana Army Ammunitions Plant (LAAP) using aerated
static piles. Lagoon sediments on the site were
contaminated with the explosives TNT, RDX, HMX, and
tetranitro-N-methyl aniline (tetryl). Initial concentrations in
the sediment were 56,800mg/kg TNT; 17,900mg/kg RDX;
2,390mg/kg HMX; and 650mg/kg tetryl. The compost pile
was formed on a concrete test pad, which had drainage
channels leading to a sump. The water from the sump was
reapplied to the compost pile. The pile weighed 4,400 kg
and contained 24 percent sediments, 10 percent alfalfa, 25
percent straw/manure, and 41 percent horsefeed, by
weight. Fertilizer (13:13:13) was also added. The
temperature was kept close to 55 °C. Initial contaminant
concentrations in the compost were 11,840 mg/kg TNT;
approximately 5,300 mg/kg RDX; and approximately 750
mg/kg HMX. Final contaminant concentrations were
3 mg/kg TNT; 45 mg/kg RDX; and 26 mg/kg HMX. Tetryl
was below detection limits in all samples. The half-life was
12 days for TNT, 17 days for RDX, and 23 days for HMX
[28][29, p. 137]. The treated material was analyzed for
several TNT transformation products (2-amino-4,6-
dinitrotoluene; 4-amino-2,6-dinitrotoluene; 2,4-diamino-6-
nitrotoluene; and 2,6-diamino-4-nitrotoluene).
Concentrations of transformation products started out low,
increased the first few weeks of the study, and then
declined thereafter [29, p. 137].
Badger Army Ammunition Plant (BAAP)
A field-scale demonstration was performed at the Badger
Army Ammunition Plant (BAAP) in Baraboo, Wisconsin using
aerated static piles. Soils at this site are contaminated with
the propellant nitrocellulose (NC). Four aerated static piles
were formed; the composition (on a weight basis) of these
piles was: two piles with 19 percent soil, 11 percent
alfalfa, 45 percent manure, 17 percent horsefeed, and 8
percent wood chips; one pile with 22 percent soil, 8 percent
alfalfa, 51 percent manure, 16 percent horsefeed, and 3
percent wood chips; and one pile with 33 percent soil, 5
percent alfalfa, 44 percent manure, 13 percent horsefeed.
Engineering Bulletin: Composting
-------
and 5 percent wood chips. Temperature was controlled by
panel-mounted Fenwal 551 thermistor-sensing temperature
controllers. Pile 1 was maintained at approximately 35°C
until Day 57 when temperatures climbed and ranged from
60° to 65°C between Day 75 and Day 94, after which
temperatures declined. Piles 2, 3, and 4 reached 55° to
65 °C within 5 days; the temperature declined after Day 65.
Table 5 shows the results of the study [29, p. 137].
Table 5
Results of BAAP Study [29, p. 137]
Pile Number
1 (19% soil)
2 (19% soil)
3 (22% soil)
4 (33% soil)
NC mg/kg
Day 1
4,933
3,093
7,907
13,086
NC mg/kg
Day 100
133
54
30
16
Percent
Reduction
97.3
98.3
99.6
99.9
Technology Status
Composting has been either considered or selected as the
remedial technology at 10 CERCLA, RCRA, other federal
facility. State, and Canadian Sites [1][2][3]. As of January
1996, the status of the sites was as follows: full-scale
remediation was completed at three sites; full-scale
remediation was in progress at two sites; two were in the
design stage of full-scale remediation; and three were in the
predesign stage. Table 6 lists the location, primary
contaminants, treatment employed, and status of these
sites. Table 6 is based on information obtained from the
August 1995 edition of "Bioremediation in the Field" [1 ] and
a draft report on the Indiana Woodtreating Corporation site
[2]. This table was modified based on phone calls made to
the various site contacts. Where possible, original sources
were obtained and used to verify site information [3].
Aerated static pile, windrow, and in-vessel composting
technologies are all commercially available at field-scale.
Mobility or transportability is not generally a constraint,
since minimal equipment is required with the exception of
in-vessel systems. Specific equipment requirements are
dependent upon the composting technology selected.
Depending on size, in-vessel systems may be transportable
or may be assembled onsite. Aeration systems for static
piles typically require onsite construction. The windrow
turners used in full-scale windrow composting systems are
transportable.
Most of the hardware components of composting
systems are available off-the-shelf and present no significant
availability problems. One of the advantages of composting
is the short lead time needed to set up a working facility.
Almost no construction is needed for windrow and aerated
static pile composting. Bulldozers and compost screens are
readily available, but sophisticated windrow turners and
mixers may require some lead time. Modified bulldozers and
front-end loaders can be used to make windrows and static
piles. Custom-made mixers require the longest lead time.
Selected cultures are available for bioaugmentation;
however, their utility is unproven. Nutrient and bulking
additives can frequently be acquired from nearby sources
(e.g., farms, horse stables, food processing plants, and
sawmills).
Composting technologies provide cost-effective treatment
for selected hazardous waste constituents. This can be
attributed in part to low capital costs, and in part to low
operation and maintenance requirements. It is difficult,
however, to generalize treatment costs since site-specific
characteristics can significantly impact costs, and many
cost estimates neglect one or more elements of the overall
cost (e.g., excavation, energy usage, disposal of residuals).
Initial concentrations and volumes, clean-up requirements,
and air emissions control systems will impact final treatment
costs. The types and local availability of amendments
employed can also impact operational costs and costs
associated with equipment and manpower required during
their application.
The composting technology (i.e., in-vessel, static pile, or
windrow composting) chosen also affects the cleanup cost.
In general, the highest capital and energy costs are
associated with in-vessel composting. Capital and energy
costs for aerated static pile composting are typically lower
than those for in-vessel composting but higher than those
for windrow composting. Windrow composting is generally
the least expensive composting technology, although full-
scale windrow composting typically requires the purchase
and operation of a windrow turner.
Costs for treating 20,000 tons of explosives-
contaminated soil over a 5-year period have been estimated
for windrow composting, aerated static pile composting, in-
vessel composting, and incineration [30]. The cost
estimates for the three composting technologies are based
on the results of pilot- and field-scale studies conducted at
the Umatilla Depot Activity Site, including the windrow and
in-vessel studies described in the Performance Data section
of this bulletin. Based on these studies, the three cost
estimates assume compost mixtures that are 30 percent soil
(by volume). The composting cycle times are designed,
based on treatability study results, to achieve 99.5 percent
removal of TNT [30]. The three composting cost estimates
each include excavation, capital (any required site
construction, equipment, etc.), operation and maintenance
(both labor and materials), monitoring, sampling and
analysis, onsite disposal, electric, water, overhead, and
contingencies [30].
The cost estimate for windrow composting assumes that
the windrows will be constructed in an enclosed structure
on a RCRA-approved pad. It also assumes that aeration and
mixing will be provided by daily turning with a commercially
available compost turner. The total 5-year project cost for
windrow composting is estimated to be $4,222,000,which
is $211 per ton of soil treated [30].
Engineering Bulletin: Composting
-------
TableG
Field Applications of Bioremediation [1][2][3]
Primary
Indiana Wood Treating
Bloomington, IN
Soil (TPAHs3, up to 357
g/kg).
Volume: 22,000 tons.
Amoco Refinery
Sugar Creek, MO
Sabliere Thouin
Assomption, Quebec,
Canada
Development and
Demonstration of Site
Remediation Technology
(DeSRT) Program
Novak. Faroi fShea&igv
Owens-Corningb
Kansas City, KS
Prinfie -Edward S stand,
PetroletHn IVoduota
Wheeling-Pittsburgh
Steel Allenport, PA
.BQUchervifle ElecJncal
",,-
Canada--
SaS ^phenanihrene, pyrens,-
naphthalene, toluene, xyienel
120,000 yd*
Soil (BTEXa, 1 35 mg/kg;
styrene, 50 mg/kg;
chlorobenzene, 10 mg/kg;
TPAHs, approx. 430 mg/kg)
TCEa or PCEa appear
randomly distributed on the
site.
Volume: 330 yd3 (250 m3)
Vbteia fradose soiij; 30,000
yd*
Soil (formaldehyde, 1 mg/kg)
Volume: 300 yd3
Voluroe:
Soil (TPHsa, 500 mg/kg)
Volume: 1,800 yd3 (1400
m3)
Soi ftransf-arrner ei, S,>
Laboratory-scale studies were
started 04/92 and completed
06/92. Pilot-scale studies were
started 06/92 and completed
07/92. Full-scale remediation
(composting and landfarming)
were started 1 1 /92 and
completed 08/94.
Labrar-Btory-scaJe and piSot-seate
studies have feeen corapleted,
underway since 08/94. SG,QOO
Laboratory-scale studies were
started 05/92 and completed
08/93. Pilot-scale studies have
been underway since 05/94.
Full-scale remediation is being
considered.
Laboratory-scale stutfes were
sa pianHact to- begin
4.?96. Cwrentty m. design^
Full-scale remediation was
completed 07/92.
studies navfe fe&af)
URderwav since -09^94 using
waste BJ -60&
f exnedtatkin is planned,
Laboratory-scale studies were
started 04/94 and completed
05/94. Full-scale remediation is
planned. Design is complete.
Baseline data are being updated
prior to anticipated remediation.
LaheratDf y*seaifi and pilot-scale
Full-scale
remediatwrt was soraptetett
Aerated static pile composting
followed by landfarming;
indigenous organisms.
Amendments were straw, horse
manure and two types of fertilizer.
Aerated static pile;,irnggenciu5 •• '•• •
organisms. Composting hatches
butfcing: igents^ Added 26-30
Aerated static pile, nutrient
addition [urea and Daramend
(Grace Dearborn amendment)].
Indigenous organisms. Experi-
menting with various types of
amendments in pilot-scale studies.
Fuij+scaie remediation -wiii fee one
windtb-ws -with vefmiculiie and
lime amendments IB a pug mitt for
a «
-------
Table 6 (continued)
Status
Treatment
Umatilla Depot Activity
Site, Hermiston, OR
Soil (TNT, 1,563mg/kg;
RDX, 953 mg/kg; HMX 156
mg/kg)
Full-scale demonstration was
started 4/92 and completed
1 2/92. Full-scale remediation
was started March 1995.
Ait
and
, few.
, ft,
and pilot-scale
studies are planned, Fafe-scale
la p1an'fted>
Windrow. Indigenous organisms.
Manure, vegetable waste, alfalfa,
and straw added as amendments.
A«rate:et static pilft, nuttiant and
bulking a^ent addltjan^ AerG.bte
sad
a Abbreviations: TPAH - Total polycyclic aromatic hydrocarbons; BTEX - benzene, toluene, ethylbenzene, and xylene;
TCE - Trichloroethylene; PCE - Perchloroethylene; TPH - Total petroleum hydrocarbons; DNT - Dinitrotoluene.
b A site contact could not be reached; therefore, site details are unknown.
The cost estimate for aerated static pile composting
assumes that the static piles will be contained within
wooden, rectangular bins constructed in an enclosed
structure on a RCRA-approved pad. The total 5-year project
cost for aerated static pile composting is estimated to be
$5,659,000, which is $283 per ton of soil treated [30].
The cost estimate for mechanically-agitated in-vessel
composting assumes that composting will be conducted in
a reactor constructed outside on a concrete foundation.
The total 5-year project cost for in-vessel composting is
estimated to be $6,280,000, which is $314 per ton of soil
treated [30].
Onsite incineration costs were developed for comparison
to the composting cost estimates. The incineration costs
Include mobilization and demobilization of the incineration
unit, but do not include excavation of the contaminated soil
or disposal of the treated material. For comparison
purposes, "treatment only" costs were developed for each
of the composting technologies. The "treatment only" costs
Include all of the items listed above except for excavation
and disposal. A comparison of "treatment only" costs is
presented in Table 7 [30].
Table 7
Estimated "Treatment Only" Costs for
Remediation of 20,000 Tons of Explosives-
Contaminated Soil in a 5-Year Period [30]
Technology
Windrow Composting
Aerated Static Pile Composting
Mechanically-Agitated
In-Vessel Composting
Onsite Incineration
Cost per Ton
$187
$236
$290
$300
EPA Contact
Technology-specific questions regarding composting may
be directed to:
Carl L. Potter, Ph.D.
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7231
Acknowledgments
This bulletin was prepared for the EPA, Office of
Research and Development (ORD), NRMRL, Cincinnati,
Ohio, by Science Applications International Corporation
(SAIC) under Contract No. 68-C5-0001. Dr. Carl Potter
served as the EPA Work Assignment Manager. Mr. Jim
Rawe served as SAIC's Work Assignment Manager. This
bulletin was authored by Ms. Julie Stegeman and Ms.
Sharon Krietemeyer of SAIC.
The following individuals have participated as members
of an expert committee that contributed to the preparation
of this document:
Dr. Dili H. Tuovinen
Dr. Joseph B. Farrell
Mr. Kurt Whitford
Dr. John Glaser
Ms. Margaret Groeber
Mr. Michael von Fahnestock
Dr. Harold M. Keener
Ohio State University
Consultant
SAIC
EPA-NRMRL
SAIC
Battelle-Columbus
Ohio Agricultural Research and
Development Center
Engineering Bulletin: Composting
-------
REFERENCES
1. U.S. Environmental Protection Agency. Bioremediation
in the Field. EPA/540/N-95/500, August 1995.
2. U.S. Environmental Protection Agency. Draft: On-
Scene Coordinator's Report - Removal Action at the
Indiana Woodtreating Corporation Site, Bloomington,
Indiana site, ID # R.D, 1995.
3. Telephone conversations with various site contacts in
January 1996.
4. U.S. Army Corps of Engineers, Toxic and Hazardous
Materials Agency. Optimization of Composting for
Explosives Contaminated Soil, Final Report. Report
No. CETHA-TS-CR-91053, November 1991.
5. Moore, R.E. Enhanced Bioactivity Treats Hydro-
carbon-Contaminated Soils. The National Environ-
mental Journal, January/February 1992. pp 34-37.
6. Michel, F.C., C.A. Reddy, and L.J. Forney. Microbial
Degradation and Humification of the Lawn Care
Pesticide 2,4-Dichloropheno'xyacetic Acid During the
Composting of Yard Trimmings. Applied and
Environmental Microbiology, July 1995. pp. 2566-
2571.
7. Haug, R.T. The Practical Handbook of Compost
Engineering. Lewis Publishers, Inc., Boca Raton,
Florida, 1993.
8. Hoitink, H.A.J. and H.M. Keener (eds.). Science and
Engineering of Composting: Design, Environmental,
Microbiological, and Utilization Aspects (An
International Symposium). Renaissance Publications,
Worthington, Ohio, 1993.
9. Savage, G., L.F. Diaz, and C.G. Golueke. The Linkage
of Composting and Bioremediation. BioCycle, October
1995. p. 62.
10. U.S. Environmental Protection Agency. Technology
Screening Guide for Treatment of CERCLA Soils and
Sludges. EPA/540/2-88/004, OSWER, Cincinnati,
Ohio, 1988.
11. Sims, R.C., D.L. Sorensen, J.L.Sims, J.E. McLean, R.
Mahmood, R.R. Dupont, and K. Wagner. Review of
In-Place Treatment Techniques for Contaminated
Surface Soils. EPA-540/2-84-003b, U.S.
Environmental Protection Agency, Cincinnati, Ohio,
1984.
12. Finstein, M.S. and J.A. Hogan. Integration of
Composting Process Microbiology, Facility Structure
and Decision-Making. In: Science and Engineering of
Composting: Design, Environmental, Microbiological
and Utilization Aspects, 1993. pp. 1-23.
13. Savage, G.M., L.F. Diaz, and C.G. Golueke. Disposing
of Organic Hazardous Wastes by Composting.
BioCycle, January/February 1985. pp. 31-34.
14. Fogarty, A.M. and O.H. Tuovinen. Microbiological
Degradation of Pesticides in Yard Waste Composting.
Microbiological Reviews, June 1991. pp. 225-233.
15. Bardos, R.P. and J.M. Lopez-Real. The Composting
Process: Susceptible Feedstocks, Temperature,
Microbiology, Sanitization and Decomposition,
Workshop: Compost in Waste Management, 1988.
16. Yusuf M., J.H. Johnson, Jr., and L. Wan. Detoxifi-
cation of Contaminated Sludge via In-Vessel
Composting. In: Proceedings of the 23rd Mid-Atlantic
Industrial Waste Conference, Pittsburgh, Pennsylvania,
1991. pp. 247-258.
17. Golueke, C.G. Bacteriology of Composting. BioCycle,
January 1992. pp 55-57.
18. Ziegenfuss, P.S., R.T. Williams, and C.A. Myler.
Hazardous Materials Composting. Journal of
Hazardous Materials, Vol. 28, 1991. pp 91-99.
19. Adenuga, A.O., J.H. Johnson, Jr., J.N. Cannon, and
L. Wan. Bioremediation of PAH-Contaminated Soil via
In-Vessel Composting. Water, Science, and Tech-
nology, 26(9-11), 1992. pp. 2331-2334.
20. Davis, K.J. and D.J. Russell. Soil Treatment
Technologies Combined. Pollution Engineering, July
1993. pp 54-58.
21. U.S. Environmental Protection Agency. Superfund
LDR Guide #6A (2nd Ed.): Obtaining a Soil and Debris
Treatability Variance for Removal Actions. Directive
9347.3-06FS, 1990.
22. U.S. Environmental Protection Agency. Superfund
LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. Directive
9347.3-06BFS,1990.
23. Day, S.M., K.J. Malchowsky, T.W. Schultz, P. Sayre,
and G.S. Sayler. Draft Issue Paper: Potential Risks,
Environmental and Ecological Effects Resulting from
the Use of GEMS for Bioremediation. U.S. Environ-
mental Protection Agency, Office of Toxic
Substances, 1993.
24. U.S. Army Environmental Center. Windrow
Composting Demonstration for Explosives-
Contaminated Soils at the Umatilla Depot Activity,
Hermiston, Oregon. Report No. CETHA-TS-CR-93043,
Aberdeen Proving Ground, Maryland, August 1993.
Engineering Bulletin: Composting
13
-------
25. U.S. Environmental Protection Agency. Test Methods
for Evaluating Solid Waste (SW-846), 3rd. Ed., through
Update IIB, 1995.
28. Federal Remediation Technologies Roundtable. Aerated
Static Pile Composting: Explosives (TNT, TDX, HMX) |
in Lagoon Sediments, pp. 2-4.
26. Keehan.K.R. Seminaron Technologies for Remediating
Sites Contaminated with Explosive and Radioactive
Wastes, Sacramento, California. U.S. Army
Environmental Center, Technical Support Division,
Aberdeen Proving Ground, Mary and, June 1993.
29. Williams, R.T., P.S. Ziegenfuss, and W.E. Sisk.
Composting of Explosives and Propellant Contaminated
Soils Under Thermophilic and Mesophilic Conditions.
Journal of Industrial Microbiology, Vol. 9,1992. pp. 137-
144.
27. Federal Remediation Technologies Roundtable. Aerobic
Composting Optimization: Explosives (TNT, RDX, HMX)
in Contaminated Soil and Sediment, pp 8-10.
30. U.S. Army Environmental Center. Windrow Composting
Engineering/Economic Evaluation. Report No. CETHA-
TS-CR-93050, Aberdeen Proving Ground, Maryland,
May 1993.
74
Engineering Bulletin: Composting
-------
-------
United States
Environmental Protection Agency
National Risk Management
Research Laboratory (Q-72)
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
Please make all necessary changes on the below label,
detach or copy, and return to the address in the upper
left-hand corner.
If you do not wish to receive these reports CHECK HERE D;
detach, or copy this cover, and return to the address in the
upper left-hand corner.
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/S-96/502
------- |