EPA-600/2-76-238
September 1976
Environmental Protection Technology Series
CONVERSION OF CATTLE MANURE
INTO USEFUL PRODUCTS
Robert S. Kerr Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories-were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-76-238
September 1976
CONVERSION OF CATTLE MANURE INTO USEFUL PRODUCTS
by
Bruce S. Dunn
John D. Mackenzie
Eugene Tseng
Materials Department
UCLA School of Engineering and Applied Science
Los Angeles, California 90024
Project No. R802933-01
Project Officer
R. Douglas Kreis
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
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DISCLAIMER
This report has been reviewed by the Robert S. Kerr Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views and
policies of the U.S. Environmental Protection Agency, nor does mention of trade
names or commercial products constitute endorsement or recommendation for use.
ii
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ABSTRACT
The purpose of the project was to design and build a pyrolysis apparatus for
cattle manure and to investigate the potential uses of the pyrolysis by-products.
A pyrolysis machine of semi-continuous feed capabilities was designed and built.
Various conditions of pyrolysis treatments were investigated and their influence
on the amount and composition of the by-products determined. High carbon
residues were found to require lower pyrolysis temperatures. The carbon content
of these residues appeared to be unaffected by the geographic location of the
original manure. Contact with interested parties and appropriate industries who
could be prospective users of each of the products was initiated to obtain
their technical expertise in evaluating these products. The pyrolysis by-
products seem to have some potential industrial applications. These by-products
include the solid residue, an oil fraction, and an aqueous fraction. The solid
residue may serve as a carbon black substitute or as a filler material in rubber,
ink, and paint. The aqueous fraction collected during pyrolysis has been
evaluated for fertilizer applications.
This report was submitted by the University of California at Los Angeles under
the partial sponsorship of the Environmental Protection Agency, Project Number
R802933-01. Work was completed as of May 31, 1975.
iii
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CONTENTS
Page
I Introduction 1
II Summary 4
III Conclusions 5
IV Recommendations 7
V Pyrolysis of Cattle Manure 8
Design and Construction of Apparatus 8
Experimental Procedure and Results 10
Discussion 15
VI Product Applications of Pyrolysis By-Products 18
Product Applications of TCD 18
Product Applications of the Oil Fraction 26
Product Application of Aqueous Fraction 29
VII Cost Analysis 31
Product Costs 31
Drying Costs ..... 31
VIII References 32
IX Publications and Inventions 33
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LIST OF FIGURES
Page
Figure 1. Applications of the By-Products of Manure Pyrolysis. ... 3
Figure 2. Plan View of Pyrolysis Unit 9
Figure 3. Flow Chart of Manure Pyrolysis Operations 11
Figure 4. Controlled Heating Rate Schedule for Pyrolysis
Operation 12
Figure 5. Influence of Pyrolysis Temperature on the Amount of
Ash (or TCD) Collected 14
Figure 6. Effect of Grinding Time on the Particle Size of TCD
(Grinding by Vail Mill) 20
Figure 7. Methods of Converting Crude Oil to Carbon Black 28
vi
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LIST OF TABLES
Table 1. Conditions for Pyrolysis and Corresponding Yields
(Pamona Manure)
Table 2. Chemical Analysis of Initial and Pyrolyzed Manure
Sampled
Table 3. Mass Balance
Table 4. Compositon of TCD from Different Localities . . .
Table 5. Properties of Hot-Pressed Tiles
Table 6. Nitrogen Content Analysis of Aqueous Fraction . .
Page
13
15
16
17
24
29
vii
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ACKNOWLEDGMENTS
We are grateful to Mr. R. Douglas Kreis, Project Officer, U.S. Environmental
Protection Agency, for his keen interest and his advice throughout the direction
of this project.
We also acknowledge the technical services, advice and encouragement provided
by the several industrial concerns whom we contacted in conjunction with this
project. They are:
Mr. Bob Cans
Cans Ink
Los Angeles, California
Mr. Cliff Finder
Cans Ink
Los Angeles, California
Mr. Albert M. Aronow
Technical Director
Sinclair Paints
Los Angeles, California
Mr. Philip J. Reiner
Da-Pro Rubber Company
Los Angeles, California
Mr. William A. Bruck
Da-Pro Rubber Company
Los Angeles, California
viii
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SECTION I
INTRODUCTION
There is a trend toward confining animal feeding operations thus producing large
amounts of orgniac waste and concentrating them in a small area. The disposal
of such large quantities of animal waste in a small area creates problems of
odor and water pollution. Due to low efficiency and high cost of handling, it
is no longer economical for manure to be transported and used as fertilizer.
Some alternative method of disposal is needed. A further attraction is the
possible utilization of waste matter to produce useful products. These will
alleviate the ever increasing burden which is placed upon our natural resources.
In California, it is estimated that there is as much as 9 x 10 kilograms of
cattle manure produced per year and these are concentrated in a few small
acreages. In 1971, a method was partially developed at UCLA for the conversion
of cattle manure into useful products. A very small apparatus was employed.
Manure was decomposed to its chemical constituents at an elevated temperature
in an atmosphere which was oxygen deficient. The gases and vapors of the pyro-
lyzed manure ash was a black, odorless, granulated solid and was named Treated
Cow Dung (TCD).
The objectives of this research project may be generally arranged into three
categories:
i. The design, construction, and actual performance of equipment for manure
dehydration and pyrolysis. This aspect of the research was designed to provide
relevant engineering data concerning manure pyrolysis and to furnish samples for
the evaluation of the resulting products (see 2 below).
2. The evaluation (by the appropriate industry) of the various secondary
products which may be produced from manure pyrolysis. These secondary products
are derived from one of the three primary by-products of the pyrolysis treat-
ment (i.e., TCD and oil and aqueous fractions). These secondary products should
have the following features: 1) they must be capable of utilizing large quan-
tities of the manure, 2) they should be of comparable quality and value to
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presently existing commodities, and 3) they should be economically feasible to
manufacture. A flow chart of various applications for by-products of pyrolyzed
cattle wastes is shown in Figure 1.
3. The contact of various parties who may aid or be interested in the research
program. This includes the contact of feedlots and appropriate industries who
may either be able to provide valueable services (e.g., supply manure, evaluate
samples) or benefit by an information exchange
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MANURE
PYROLYZER
LIQUID
FRACTION
SEPARATOR
OIL
AQUEOUS
SOLID
RESIDUE
1
SIZE
REDUCTION
CARBON
BLACK
SUBSTITUTE
1
FILLER
FRACTION-
ATION TO
PETROCHEM
ICAL PROD.
CARBON
BLACK
FERTILIZER
PRINTING
INK
PAINT
RUBBER
TILES
CHARCOAL
BRIQUETTES
Figure 1. Applications of the By-Products of Manure Pyrolysis.
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SECTION II
SUMMARY
An apparatus for pyrolyzing cattle manure was designed and built, and the
potential product applications which utilize the pyrolysis by-products were
investigated. The pyrolysis equipment has a semi-continuous feed capability.
Various conditions of pyrolysis treatments were studied and their influence
on the amount and composition of the primary by-products was determined.
A highly carbonaceous solid residue was obtained at lower pyrolysis tempera-
tures and the carbon content was unaffected by the geographic location of the
original manure. Mass balance calculations were performed and accounted for
the distribution of the chemical constituents of the manure among the primary
by-products of pyrolysis.
Three primary by-products were obtained from the pyrolysis of cattle manure:
a solid carbonaceous residue, an oil fraction, and an aqueous portion.
Numerous secondary products may be derived from these primary by-products.
The solid residue was used as a carbon black substitute and filler in printing
ink, paint, rubber, tiles and charcoal briquettes. The oil was fractionated
into carbon black while the aqueous portion was evaluated for fertilizer
applications. Appropriate industries who could be prospective users of each
of the products were contacted and helped in the evaluation of these materials.
The most viable application appears to be the use of the solid residue as a
carbon black substitute. A brief cost analysis concerning the production of
this material was performed.
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SECTION III
CONCLUSIONS
Cattle manure can be utilized in many useful products by pyrolyzing the manure
and using the various by-products either by themselves or by incorporating them
with other materials.
The optimum pyrolysis temperature depends upon the desired end product. For
product applications where the carbonaceous residue, hereafter referred to as
Treated Cow Dung (TCD), is used for a carbon black substitute, a lower pyrol-
ysis temperature is used to retain more carbon in the ash.
In cases where high carbon content is desired, the TCD possesses fairly con-
sistent carbon concentrations, regardless of geographic location.
When pyrolyzed ash is substituted for carbon black in product applications,
the size of the powdered ash is significantly larger than that of carbon black
and further size reduction is necessary.
Ink and paint of acceptable quality can be made with pyrolyzed cow manure ash
in partial substitution for carbon black.
Crude oil condensed from the pyrolysis of manure can also be used to produce
carbon black of quality equal to those used in industry.
For large volume applications, the use of TCD as a filler in ceramic tile holds
promise. Tiles can be produced which are equal in strength and durability to
commercial tiles.
The water fraction holds promise as a fertilizer carrier when upgraded with
primary nutrients.
TCD has been successfully used as a filler and colorant in rubber. The optimum
characteristics for this application are, at present, not known.
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TCD with high carbon content has been qualitatively assessed as a principal
constituent of modified charcoal briquettes.
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SECTION IV
RECOMMENDATIONS
At the inception of this research program, it was hoped that both sufficient
data for evaluating the technical factors and the economics of manure pyrolysis
and sufficient pyrolysis products for complete application evaluation could be
produced. Such additional data and additional samples can only be made avail-
3
able from the operation of a small pilot plant of approximately 9.08 x 10 kg
per day capacity, the preliminary results and analyses provided by the indus-
trial contacts were encouraging in many respects. They stress, however, that
considerably larger sample sizes are required in order to perform a thorough
industrial-scale evaluation. Thus, a larger scale research program for this
essential intermediate step is recommended. This program will not only supply
the larger sample quantities involved for thorough evaluation but also enable
the pyrolysis apparatus to be further adapted towards economic production
methods. For example, continuous pyrolysis could be implemented. Certain
equipment features could be improved (e.g., use of cold traps should be modified
or a high temperature seal for moveable parts developed).
In the product field, a more critical analysis concerning the fractionation and
combustion of crude oil is needed. Due to the energy shortage, this fraction-
ation is of utmost importance. For the other items such as TCD briquettes,
tiles, and carbon black substitutes, detailed economic analysis should be per-
formed to determine which combination of products offers the best return on
investment.
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SECTION V
PYROLYSIS OF CATTLE MANURE
This section considers all the experimental aspects concerning the design and
operation of the manure pyrolyzer. The overall objective here was to obtain
relevant engineering data about the pyrolysis mechanisms and to provide suffi-
cient quantities of the pyrolysis by-product for evaluation purposes. The
pyrolyzer design, operating procedure, and experimental results are discussed
separately within this section.
DESIGN AND CONSTRUCTION OF APPARATUS
The process for manure treatment involved a semi-continuous pyrolyzing
unit (Figure 2). The pyrolyzer consisted of an inner rotating cylinder
(0.3 m by 0.3 m) constructed of Type 304 stainless steel, No. 10 mesh screen.
The end plates of the cylinder were machined from 1.27-cm, Type 327 stainless
steel. One of the end plates of the rotating screen drum was mounted on an
axis connected to the motor drive. The end plates were supported by three
rigid cross beams, which had many attachment notches for varying the overall
cylindrical screen size. The other end plate was mounted on a tube supported
by a 8.9-cm adjustable bearing. This tube provided the entrance for the semi-
continuous feed. The end of the feed tube had provisions for a semi-continuous
piston loader which was not installed due to time limitations. A removable
cap was used instead. The motor drive shaft was connected to the motor by
means of a rubber joint to allow for mismatches in concentricity.
The shaft itself was supported by another 2.54-cm adjustable bearing. The
screen was housed within an airtight, welded, rectangular enclosure with a
removable faceplate which enabled ease of cleaning and maintainance and screen
adjustments. The storage container and a slide plate that enabled periodic
observations of the progress of pyrolyzation. The pyrolyzer was gas-fired
using adjustable gas jets. Gas pressure was measured in inches of tUO by a
manometer to insure consistent heating rates for pyrolysis. A gas valve was
installed for gas cutoff of two burners for temperature maintenance. The gas
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(1) No. 10 Mesh Screen
(2) End Plates
(3) Axis
(4) Cross Beam
(5) Feed Tube
(6) Adjustable Bearing
(7) Motor Drive Shaft
(8) Motor
(9) Rubber Joint
(10) Adjustable Bearing
(11) Housing
(12) Storage
(13) Gas Jets
(14) Valve
(15) Bricks
(16) Frame
(17) Flue
(18) Drying Chamber
(19) Condensing Pipe
(20) Condensing Jars
(21) Glass Tubes
Figure 2. Plan View of Pyrolysis Unit.
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burners were located on the bottom of the outer furnace. The rectangular,
stainless steel pyrolyzer unit was enclosed in refractory bricks held together
by an angle-iron frame to prevent unnecessary heat loss. The pyrolyzer unit
was supported by an angle-iron frame resting on the outer furnace. Two adjust-
able ventilation-exhaust flues were located on top of the outer brick furnace
to aid heat retention control. A small chamber on top of the outer furnace
allowed predrying of wet manure. The exhaust was directed into a fumehood.
A 5.1-cm pipe at the top of the stainless steel pyrolyzer drew the vaporized
fraction of the manure during pyrolysis. The 5.1-cm pipe led to a series of
3 condensing jars with interconnecting water-cooled glass tubes. Draw was
provided by a small vacuum and a small air release valve was attached before
the vacuum to prevent overloading.
The roof of the outer furnace was supported by angle iron and ceramic plates.
EXPERIMENTAL PROCEDURE AND RESULTS
A flow chart of the total manure treatment operation is shown in Figure 3. The
first step in pyrolyzation was to determine water content of the sample to be
pyrolyzed. The samples were first placed in a small preheating chamber on
top of the pyrolysis machine. A predetermined batch (usually 1,000-2,000 grams)
was loaded through the feed tube into the pyrolyzer.
Temperatures were checked every five minutes to insure that the heating rate
was identical for each sample. The heating rate is shown in Figure 4. Once the
desired pyrolyzation temperature was reached, the motor drive rotated the inner
stainless steel drum. The rotation, together with the pulverizing action of
the alumina balls inside the drum, reduced the larger pieces of cow manure and
allowed increased surface reaction. Once the manure was pyrolyzed, the pulver-
izing action of the alumina balls forced the reacted ash through the stainless
steel mesh, where it then dropped into a storage container. The storage con-
tainer was located under the heating zone of the furnace to prevent further
pyrolyzation. Small samples could be taken during pyrolyzation to check
its progress without affecting the process. As soon as vapors could be observed
in the primary condensing tube, the small vacuum was turned on to draw the
10
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WET
MANURE
H90
DRYER
FUEL
PYROLYZER
FUEL
STORAGE
CONDENSING
UNIT
Figure 3. Flow Chart of Manure Pyrolysis Operations.
11
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500
LU
400 -
ai
o
C/3
LU
UJ
CC
DC
D
DC
UJ
a.
5
UJ
I-
300
200 -
100
15 30
TIME, MINUTES
45
60
Figure 4. Controlled Heating Rate Schedule for Pyrolysis Operation.
12
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vapors through the set of 3 condensers. The minimum vacuum needed to pull the
vapors through the system was used. The purpose of the minimum vacuum was to
get maximum condensation while preventing an overload on the vacuum. When the
vapors had stopped emanating, the run was considered complete. The motor drive
was continued to ensure that all pyrolyzed ash had passed the stainless screen.
Ventilation flues were opened for cooling. The pyrolyzed ash was left in the
storage container for a minimum of 30 minutes to ensure cooling to prevent
spontaneous combustion once it was exposed to air. The jars containing the
condensed aqueous fraction could be removed immediately for weighing. The
aqueous fraction was separated into its oil and water components by centrifug-
ing. The specific results of the various pyrolysis experiments are discussed
below.
Table 1 lists the more significant pyrolysis results. The effect of different
time and temperature conditions on the effective yield is also shown. Generally
it was found that for a relatively low temperature of pyrolysis, there was
more ash produced, while at a greater pyrolysis temperature, there will be a
larger aqueous fraction. This result is also shown in Figure 5. During high
temperature pyrolysis, more carbon was fractionated from the manure and con-
densed into the oil from the aqueous fraction. For applications where TCD was
Table 1. CONDITIONS FOR PYROLYSIS AND
CORRESPONDING YIELDS (Pamona Manure)
Load
(grams)
1500
1500
1000
1000
1500
1000
Temperature
(degrees centigrade)
225°
240
300
325
325
350
Time
(hours)
3.0
2.5
2.5
2.5
2.5
2.5
Solid Yield
(%)
53.5
45.2
46.5
25.0
41.3
34.8
Liquid Yield
(%)
32.1
11.4
27.6
19.9
16.3
19.1
13
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60
Q
_i
UJ
O 50
X
GO
Q
LLJ
r-
O
O
o
40
30
200 300
PYROLYSIS TEMPERATURE, DEGREES CENTIGRADE
400
Figure 5. Influence of Pyrolysis Temperature on the Amount of Ash (or TCD) Collected.
14
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used as a black pigment or a filler, pyrolysis was carried out at relatively
low temperature (300°-325° C) since more carbon was left in the ash at these
conditions.
The time of predrying had substantial effect on the total water fraction gener-
ated during pyrolysis. Predrying decreased the amount of water contained in
the aqueous segment (moisture content of the received manure samples varied from
14 to 25 weight percent). Increased water content affected the initial rise in
temperature. For these samples, an increase in gas pressure to the burners was
necessary in order to obtain the desired heating rate.
A typical chemical analysis of both the pyrolysis by-products and the initial
manure sample is shown in Table 2. Similar results were obtained with all the
manure samples investigated in this work.
Table 2. CHEMICAL ANALYSIS OF INITIAL AND
PYROLYZED MANURE SAMPLED
Raw Manure
Oil Extract
Water
Ash
% Carbon
23.82
54.71
0.74
30.07
% Hydrogen
3.80
7.78
1.49
% Nitrogen
1.85
5.38
0.27
DISCUSSION
The entire pyrolysis treatment was subjected to a mass balance analysis. In
this procedure, all chemical constituents present before and after treatment
were compared. Naturally, complete agreement was desired. This analysis was
valuable because it described the distribution of the various elements. Pyrol-
ysis treatment schedules may then be adjusted to obtain various distributions.
The results of a mass balance calculation for the present study are shown in
Table 3. Similar results were obtained for all manure samples. This particu-
lar run was selected because of its fairly high efficiency (i.e., 91% efficiency
15
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or 9% stack loss). The objective of Table 3 Is to have item (a), the chemical
constituents of the raw manure, compare favorably with item (e), the total
chemica1 constituents of the pyrolysis by-products. This balance is summarized
in item (f), the accountability ratio (e/a). Good agreement is obtained for
carbon (91%). This is probably the most important element for product applica-
tion purposes(i.e., oil, carbon black substitute as given in Section V). Only
fair agreement was found for hydrogen (66%), while poor results were observed
for nitrogen (39%). These values for hydrogen and nitrogen were undoubtedly
due to the stack loss. Other mass balance calculations using pyrolysis treat-
ments with even greater stack losses (i.e., greater than the 9% value in Table
3) exhibited correspondingly similar results. That is, good agreement for
carbon but even worse values for hydrogen and nitrogen than were observed here.
Table 3. MASS BALANCE
(per 1,000 gms, 91% efficiency)
a) Raw Manure
b) Oil Extract
c) Water
d) Ash
e) Total (b), (c) , (d)
f) Accountability Ratio
(e/a)
C(gm)
238
62
2
152
216
91%
H(gm)
38
9
8j.
/s
8
25
66%
N(gm)
18
6
1
-
7
39%
Thus, it is reasonably certain the stack losses include water vapor and a
volatile fraction (containing nitrogen) which were not condensed. These losses
are present because of the draft utilized in the system. The draft provided
by the vacuum was needed to draw out the vapors. Even with the draw, much of
the hydrocarbons were burned within the pyrolysis chamber before being drawn
and condensed. Without the vacuum, very little oil would be condensed.
The amount of the stack loss was considerably greater than expected. The
primary reason was an inefficient condensing system. Even with the modified
16
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condensing system, an average 10-percent stack loss was generally observed. A
variable temperature run was made in which various temperatures were equilibri-
ated until no additional condensate appeared. Intervals of 50° C in a range
of 200° C to 400° C were tried. The loss of condensable vapors were close to
50% indicating that much of the vapor fraction was being burned in the pyrolysis
chamber.
Variable loads of manure ranging from 500 grams to 2,000 grams were also
investigated. For the larger loads, longer pyrolyzation times were not required.
The initial heating was slower in the beginning but was adjusted to follow the
heating curve by varying the amount of gas. It was previously mentioned that
the chemical analysis of the pyrolysis by-products (Table 2) was similar for
all the manure samples tested. In Table 4, a comparison of the hydrogen and
carbon contents of TCD samples from this and other studies was presented.
The localities are Indicated. The agreement is excellent.
Information such as this is important for industrial applications. The implica-
tion here was that fairly uniform carbon contents of TCD may be obtained from
pyrolysis regardless of geographic location. The notion that properly treated
manure contains a certain equilibrium content of carbon was strongly suggested.
Although this equilibrium content depends upon processing conditions , other
aspects such as feed ratios are of secondary importance as far as the carbon
content of TCD is concerned. This result was quite encouraging and should be
of interest for future pilot plant operation.
Table 4. COMPOSITION OF TCD FROM
DIFFERENT LOCALITIES
C
H
r
Brawley, Calif.
30.56%
1.19%
Colorado
24.28%
1.16%
Ohio
30.07%
1.49%
17
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SECTION VI
PRODUCT APPLICATIONS OF PYROLYS1S
BY-PRODUCTS
Tliis section considers the various efforts made towards evaluating the products
which may be fabricated using the pyrolysis by-products. The by-products are
TCD, oil, and the aqueous fraction. In some instances (e.g., TCD) several
viable products have been investigated while in other cases (e.g., the aqueous
fraction), only one application has become evident. Each of these aspects are
considered in detail.
PRODUCT APPLICATIONS OF TCI)
TCD is generally used for two purposes: as a carbon black substitute and as a
filler material. In paint, ink, and rubber applciations, it serves in both
capacities. The tiles utilize TCD strictly as an inexpensive filler. Each of
these applications are discussed in detail below.
Ink
The pyrolized manure ash can be used as a carbon black substitute and filler
in newsgrade black ink. The preparation of the ash for this purpose involves
particle size reduction by ball-milling. The TCD ash is then mixed in an ink
mill with other additives in the following ratio:
Mineral Oil 65%
Resins & other body modifiers 15%
(heavy linseed oil)
CB (Commercial carbon black) 10%
TCD 10%
Toner (added later l/2-2w/%)
Drier (added as needed, l/2-2w%)
18
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By substituting ball-milled TCD for up to 50% of the total carbon black content,
ink of a satisfactory quality can be produced. Industrial evaluation was made
by three commercial operations: Can's Ink (an ink manufacturer), Geiger
Brothers (the printers of the Farmers Almanac), and Sinclair Paints.
The generaJ conclusion reached by these, industrial users is that TCD carbon
black ink can definitely be used in certain specific applications. Because of
its low tinting quality (very low black jetness) TCD inks may only be used
when quality inks are not necessary (newspapers, flyers, etc.)- Unfortunately,
TCD with high carbon content did not significantly improve the tinting. The
reason for this is that the ash content of TCD is considerably greater than
that of the carbon black it is replacing.
Another problem is that of the TCD particle size. Carbon black powders
produced by commercial processes for use in ink are on the order of millimi-
crons whereas the minimum size of TCD, obtained by ball milling, is one micron.
The studies concerning the influence of grinding time on the particle size of
TCD is shown in Figure fa. Because of the particle size limitation, only the
minimum-sized particles were supplied for evaluation. From the above discus-
sion it is evident that if finer-sized particles could be obtained, better
inks could be fabricated and the use of extra body modifiers would not be
necessary. Finer particle sizes are desired because it increases the surface
area thus improving wetting characteristics.
Another problem of large particle sizes is that the ink will not adhere to a
(3)
high-speed roller so that ink droplets will fly off the roller in a mist.
Caking due to dry ink will also occur. Furthermore if any sand is present in
the TCD (sand may be inadvertently collected from the pens), its inherent
grittiness makes the ink not amenable to high-speed applications. The soft
lead type will be quickly worn out.
The more specific comments regarding the ink application are given as follows:
Mr. R. A. Geiger, the editor of the Farmers' Almanac, has used our ink on a
Miehle Vertical Press. The initial worry of the grittiness and large size
19
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Figure 6. Effect of Grinding Time on the Particle Size of TCD. (Grinding by Ball Mill).
20
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did not prove to be an important factor in the overall use of the ink. The
problem encountered was that of the body of the ink being too thin. This caused
the ink not to lay on the printed sheet quite as well as desired. In general
then, the TCD-based ink appears to have some promise. However, Mr. Geiger has
informed us that a final evaluation can only be made with considerably larger
samples of TCD.
The research labs of Sinclair Paints evaluated the TCD ash for tinting strength.
They reported that the ash had approximately 5% the tinting strength of carbon
black. This conclusion was essentially confirmed by Cans Ink.
In conclusion then, further research is needed to evaluate inks made with mix-
tures of varying proportions of carbon black to TCD. Further information on
the possibility of increasing toning is necessary. It would appear that there
is a real opportunity here to utilize TCD.
Paint
Pyrolyzed manure ash can also be used as a filler and color pigment in paint.
The pyrolyzed ash was substituted for lampblack in the paint. As in the case
of the ink application, the pyrolyzed ash sample was milled to approximately
one micron.
Samples of the TCD ash were sent to the research laboratories of Sinclair paint
for evaluation. Preliminary evaluation indicated that the carbon content of
the TCD must be in excess of about 30% in order for the TCD to be useful for
black paint. Secondly, average particle size must be less than one micron.
Samples containing the greatest carbon content (30%) were sent. Two samples
of paint were made from the milled TCD ash. The first sample was prepared by
substituting 25% of the TCD for the normal quantity of lampblack. A test paint
was fabricated. The objective here was to test the pigmentation quality of
TCD. Sample 2 was prepared by using 12.5 times as much TCD as in Sample 1 but
without lampblack. In this case both the filler and pigment qualities are
examined. The evaluation involved a drawdown comparing samples 1 and 2 with
a standard paint. Examination of the drawdown results show that for both
samples the tinting strength was somewhat below standard. If sufficient TCD
21
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added to match the tinting strength level of the standard, the resulting
product would be applicable as a pigment extender. It was clear that further
research and development are necessary to ascertain the variation of tinting
strength with the carbon content of TCD and with the behavior of TCD-lampblack
mixtures. It appears that for paint application, size and carbon content are
important but that the source of the TCD is unimportant.
Rubber
The pyrolyzed manure ash (TCD) has been successfully substituted for carbon
black and filler in rubber. The TCD was prepared in a manner similar to that
previously described for ink and paint applications. It was ball milled to
a particle size between 1 and 25 microns. Particle sizes in excess of this
range are unacceptable for rubber applications.
Eight rubber companies as well as the Rubber Tehhnology Laboratory of the
University of Southern California were contacted concerning the evaluation of
TCD as a filler and pigment for rubber. Only the Da-Pro Rubber Company and the
University of Southern California were willing to evaluate the TCD samples. The
rubber samples made up by both laboratories appear to be inferior to existing
rubber made with carbon black. The general conclusion is that the particle
size of TCD was too large and that residual salts and other unknown constitu-
ents in TCD were the main causes of its inferior performance.
Rubber samples prepared with TCD were compared to samples of standard rubber.
The TCD was added to totally replace the carbon black content. The typical
batch formulation of the TCD rubber is given below:
ethylene propalene rubber 100 gins
naphtenic oil 25 gms
stearic acid 1 gm
ZnO 5 gms
TCD 50 gms
petrolatum 3 gms
sulphur (for curing) 1.5 gms
curative agent (accelerator) 2.34gms
22
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The examination indicated that the high level of impurities in the TCD caused
sponginess and blistering of the raw batch. The impurities essentially arise
from the low temperature pyrolysis conditions used to obtain a high carbon
content. The particle size was deemed adequate for filler purposes but was
much too coarse to be used as a carbon black substitute. Thus, the sample fabri-
cated by Da-Pro, where TCD was substituted for carbon black, possessed inferior
properties to a standard rubber specimen (i.e., with carbon black). The samples
evaluated contained the highest content of carbon (about 30%). Samples made
with less than 30% carbon are unacceptable as a black pigment. However, the
carbon content is unimportant as far as filler application is concerned.
The Shore hardness value (scale A) was 43 as compared to the standard sample's
4 2
value of 55. Tensile strength of the standard was 9.8 x 10 bm/cm . Thus the
rubber could technically be used in non-critical applications which require low
stress levels, e. g., rubber mats, automotive stripping, and certain types of
hosing. However, the problems of blistering and sponginess must be solved
before utilization is viable.
The conclusion reached by this industrial evaluation was that TCD can be
successfully used as a filler material in rubber. It may be substituted for
clay, but this requires that the TCD be totally pyrolyzed so that all traces of
nitrogen are removed. For this case, the carbon content is unimportant and high
temperature pyrolysis is required. The carbon may be driven off into the oil
fraction. A preliminary analysis indicates that TCD is economically competitive
with washed clay as a filler in rubber.
In conclusion then, TCD holds promise only as a filler material in certain
types of rubber. Its low carbon content was inferior to lamp-black as a
pigment. Again the varying sources of manure were not an important factor.
Tile
TCD may be utilized as a filler in a ceramic tile replacing the conventional
fillers. The tiles produced using TCD as a filler are odorless, waterproof,
durable, strong, hard, and incombustible. They can be made in a variety of
colors and decorative patterns by adding different materials to the tile
surface during manufacture.
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Physical properties such as density, moisture absorption, bending strength,
and impact strength compare favorably with conventional materials.
The process of manufacturing these tiles consists of uniformly blending the
bal1-mi]Led, carbonaceous aluminosilicate residue (TCD) with powdered waste
glass (from bottles and jars) then heating the mixture while it was contained
in a mold. the processing temperature varies from 700° C to 900° C, depending
upon thickness. Once the mold and mixture has reached temperature, the mold
4 2
was removed from the kiln and a pressure of approximately 3.5 x 10 gin/cm is
applied. The pressure during the heat treatment was used to coalesce the
homogeneously-mixed TCD filler with the glass, so that they were fused together
into a single mass. Tile properties were tested. Their characteristics are
listed in Table 5.
Table 5. PROPERTIES OF HOT-PRESSED TILES
3
Density, controllable 1.8 to 2.4 g/cm
Incombustible Class A
Flexurai strengths 4.2x10 to 5.6x10 grams/cm
Apparent impact strength 128 Newton-meters at 1.8g/cm '
density
Abrasion wear index (Taber) 55 to 130 (minimum acceptable is
35)
Moisture absorption as
per CTI (Ceramic Tile Institute)
Standard 32-12 2.2% at 1.8g/cm density
Wt. per area 1.95 grams per square centimeter
.95 cm thickness
Hardness, Moh scale 6
Decoration bulk and surface colors possible;
glazed easily
Miscellaneous can be painted, glued, non-toxic
and odorless
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Charcoal Briquettes
Charcoal Briquettes can be made with TCD. The pyrolyzed ash can be used
directly out of the pyrolyzer without any further size reduction. A 1% corn
starch solution is used as a binder. The solution is mixed with the TCD and
4 2
put into a mold which is then pressed to about 3.5 to 7.0 x 10 gm/cm . The
compacted mass was then allowed to dry. Small scale production with a labora-
tory press and a commercial 1.8 x 10 kg briquetting press has been achieved.
One field of use found for charcoal briquettes besides commercial uses was the
use of the briquettes as a fuel supplement in coal-fired utuilities. Presently,
the only fuel supplement used in the cellulosic fraction of municipal solid
wastes. Cellulosic wastes are extremely awkward to handle, due to bulkiness.
Samples of TCD briquettes were sent to the Union Electric Co., St. Louis, Mo.,
which uses fuel supplements. As of this date, the evaluation was not carried out
due to a long strike at Union Electric Co. Experiments indicate that one draw-
back could be the extremely high ash content (70%-80%) of the briquettes. Its
briquetted form lends itself to easy handling, transportation, and storage.
In only qualitative field tests, the TCD briquettes were compared against a
commercial brand of charcoal briquettes. It was noted that the TCD briquettes
lighted with relative ease and reached maximum temperature much sooner,
although they did not reach as high a temperature nor did they sustain their
temperature as long. No odors of manure or any other foul odors were emitted
during their combustion. Food was actually cooked over these briquettes and
no unusual taste was noted. Because of its high ash content, the largest use
of the TCD briquette would be as a fuel supplement in the newer stirred-bed,
coal-fired utuilities and gasifiers. The ash would not be a problem in stirred-
bed, coal-fired utilities and gasifiers or in a stirred-bed, coal-fired
boiler (2).
Foaming Agent
In work performed prior to this grant, TCD was used as a foaming agent in the
fabrication of lightweight foamed glass. The TCD was milled to a minus two
hundred mesh particle size and mixed with glass powder. This mixture was put
25
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in a mold and fired to a temperature at which the glass softens. At these
temperatures, the TCD decomposes and the gas generated creates small pores in
the softened glass. Upon cooling, the small pores are trapped and a cellular
structure results. The light-weight glass foam has potential as a good acous-
tical and thermal insulator for building applications. Details of foamed glass
can be found in patents 3,811,851 and 3,900,303.
PRODUCT APPLICATIONS OF THE OIL FRACTION
The oil fraction collected from the pyrolysis treatment has been described in
Section V. Such TCD oil appears to have potential in two different applications.
One is the direct use as a crude oil while the other involves the fabrication
of carbon black from crude oil. Each of these applications is discussed below.
Crude Oil
The liquid fraction accumulated by condensing the vapor emitted during pyrolysis
can be separated into an oil fraction and an aqueous fraction by centrifuging.
This crude oil has a chemical composition which essentially resembles that of
natrual crude oil. The chemical composition is not primarily dependent on the
origin of the manure but on the pyrolysis process. Preliminary evaluations
suggest that the TCD crude oil can be readily used as a fuel oil. Early work
by Chevron Oil Company also indicated that it can be fractionated into various
petroleum products.
Oil companies contacted included the Union Oil Company, Standard Oil Company,
Gulf Oil Company, and Shell Oil Company. These companies indicated that
because of the relatively small quantities of TCD crude oil which can ultimately
be produced as compared to oil from natural sources, they have little interest
in evaluating the material at present.
The subsequent utilization of TCD oil is thus wholly dependent on the economics
of mass production. It appears that in the future, if pyrolysis of manure will
be carried out at feedlots on a large scale, small, local, independent industries
must be contacted to exploit the utilization of the TCD oil as a heating fuel.
26
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Because of the limited quantity as compared to present natural oil, the possi-
bility of its use in fractionation into various hydrocarbons, such as gasoline,
with refineries is remote.
Carbon Black Production from TCP Oil
Carbon black has been produced on a laboratory scale from the TCD crude oil.
Information was provided by Cities Service Co., Petrochemical Research Division,
(Mojave, Calif.) on carbon black production. The TCD crude oil has been con-
verted to carbon black using such basic production methods. Carbon black was
produced by the incomplete combustion of the oil vapor* (4).
Two methods of obtaining carbon blacks were tried (Figure 7).
Open Pan Burning —
This consisted of igniting an open pan of oil in an enclosed hood, leading to
filter and exhaust equipment.
Furnace Blacks —
Furnace blacks were produced by incomplete combusion of oil vapor. A cure,
small-scale, carbon black production furnace was made in the laboratory by
using pipes and pipe fittings. Oil spray was mixed with a gas-rich air mixture
and ignited. The quench action of the steam created the incomplete combustion
of the mixture. Carbon black was then collected by a filter.
Small samples of carbon black collected from both of these methods were tried
in ink and then evaluated by an independent ink manufacturer (Cans Ink). The
carbon black was comparable in quality to commercial carbon black. For example,
the ash content was less than 1% and the average particle size by electron micro-
scopy was essentially the same as that of commercial furnace black. The ink
made was entirely acceptable. It would appear that such TCD oil-carbon black
will be satisfactory as a replacement for commercial carbon black in every
application.
27
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SURFACE BURNING
TO COLLECTION EQUIPMENT
OPEN PAN BURNING
^:$$g&&fe£J2i ^d?^'
GAS RICH
AIR MIXTURE PILOT FLAME
TO COLLECTION
EQUIPMENT
STEAM QUENCH
FURNACE BLACK
Figure 7. Methods of Converting Crude Oil to Carbon Black.
28
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PRODUCT APPLICATION OF AQUEOUS FRACTION
The liquid fraction condensed during pyrolysis can be separated into an oil
fraction and a water fraction. The water fraction holds promise as a fertilizer.
This application is virtually the only one identified thus far for the aqueous
portion.
The liquid fraction was centrifuged at 1,500 revolutions per minute for five
minutes to separate the oil and water. The water was then passed through filter
paper to remove some of the finer suspended solids. The sample was then sent
to Arizona Agrochemical, Phoenix, Arizona, for analysis and evaluation of its
potential as a fertilizer. The analysis is shown in Table 6. They found that
the liquid did not have sufficient fertilizer value with respect to primary
nutrients (nitrogen, phosphorus, and potassium). The company suggested upgrad-
ing the liquid with these elements added from other sources, and it would then
be suitable for fertilizer applications. In its present state, the aqueous
fraction could be used as a carrier for primary nutrients. In this case, the
liquid was used in place of water, and the few components present (Table 6)
were obviously of greater nutrient value than water. For on-farm tests, sub-
stantially larger batches were needed (in excess of approximately 400 liters).
Table 6. NITROGEN CONTENT ANALYSIS OF AQUEOUS FRACTION
% Total Nitrogen (N)
% Organic Nitrogen (N)
% Nitrate Nitrogen (N)
% Ammoniacal Nitrogen (N)
% Available Phosphoric Acid
% Potash (K 0)
% Total Sulfur (S)
% Total Soluble Salts
PH
0.82
0.79
0.03
0.44
<0.02
0.03
0.05
2.10
8.05
29
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The equipment was inadequate to furnish such large quantities. It is evident
that a more efficient condensing system would significantly upgrade the aqueous
fraction in nitrogen content. The nitrogen "accountability ratio" (Table 3)
was lowest of all elements because of difficulty in condensing the nitrogen
containing volatiles. The value of this aqueous fraction will undoubtedly be
much enhanced when an improved condensing system is incorporated in the
pyrolyzer. For instance, in earlier, very small-scale, controlled experiments,
a nitrogen content as much as 11.6% was noted.
30
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SECTION VII
COST ANALYSIS
PRODUCT COSTS
The optimum conditions of pyrolysis are dependent upon the desired by-product.
From this report it is evident that the use of the TCD as a carbon black substi-
tute and filler is likely to bring the greatest return on investment. For
these applications the manure is pyrolyzed at relatively low temperatures. The
cost of producing pyrolyzed ash has been estimated. For a plant to process
approximately 2.72 x 10 kg (30,000 tons) of manure (25 percent water) per year,
the cost of the ash is on the order of $3.50 to $4.00 per 9.08 x 10" kg (ton). The
crude oil is taken as a credit against costs. For the carbon substitute and
filler applications, size reduction is necessary. A maximum total cost of $10
2
per 9.08 x 10 kg (ton). The crude oil is taken as a credit against costs.
For the carbon substitute and filler applications, size reduction is necessary.
2
A maximum total cost of $10 per 9.08 x 10 kg (ton) is estimated to produce the
highly carbonaceous residue in a form of fine powder, nearly as fine as carbon
black. Current rubber filler substitutes sell for approximately $.015 per
.45 kg (pound). If fine carbonaceous ash were sold for approximately the same
2
price, the net return would be on the order of $20 per 9.08 x 10 kg (ton).
The above analysis clearly indicates that the pyrolyzed ash may be a viable,
economically successful product when used as a carbon black substitute or filler.
DRYING COSTS
The pre-drying of the manure (assumed 25 percent water) does not present much
of an economic problem. In the reported experiments, manure was predried in
a small chamber on top of the pyrolysis unit. The flue gases from the pyrolyzer
were used to dry the wet manure. In a large tonnage application, a direct heat
rotary unit could be installed before the feed mechanism to the pyrolyzer.
Utilizing the exhaust flue gases of the pyrolysis furnace, the manure can be
thoroughly dried. In this case, the only additional energy expenditure associ-
ated with drying would be the electrical requirement needed to turn the rotary
drier unit. This cost is slight ($.10 to $.12 per 9.08 x 10 kg).
31
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SECTION VIII
REFERENCES
1. Burgess, K.A., C.E. Stott and W.M. Hess. Vulcanizate performance as
function of carbon black morphology. Rubber Chem. Technol. 43: 230-248
(1970).
2. Gillmore, D.W. Personal communication (1974).
3. National Association of Printing Ink Manufacturers. Printing ink handbook.
National Association of Printing Ink Manufacturers. New York (1967).
4. Schubert, B., P.P. Ford and F. Lyon. Analysis of carbon black, p. 179-243.
In: Encyclopedia of industrial chemical analysis, Vol. 8, John Wiley and
Sons, New York (1969).
5. White, R.K. and E.P. Taiganides. Pyrolysis of livestock wastes, p. 190-194.
In: Proceedings of international symposium on livestock wastes. American
Society of Agricultural Engineers, St. Joseph, Michigan (1971).
32
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SECTION IX
PUBLICATIONS AND INVENTIONS
A paper entitled: "Product Applications of Treated Livestock Waste," was
presented at the International Symposium on Livestock Wastes at the University
of Illinois April 23, 1975. The paper will be published in the Symposium
(2)
Proceedings. An abstract of this paper was previously submitted to EPA.
The support provided by EPA was gratefully acknowledged.
"Invention Disclosure" forms were submitted for the pyrolysis equipment
developed during this project. The title is "Apparatus for Pyrolyzing Cattle
Manure" with B. Dunn and E. Tseng as co-inventors. This disclosure was submitted
to Mr. F.L. Meadows, Chief, Grants Operations Branch, EPA, Washington, B.C.
20460, by Miss Josephine Opalka, Patent Administrator of the University of
California on August 19, 1975.
33
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TECHNICAL REPORT DATA
(/'lease read Instructions on the reverse before r
1 REPORT NO.
I-PA-600/2-76-238
3. RECIPIENT'S ACCESS I ON-NO.
4. TITLL AND SUBTITLE
CONVERSION OF CATTLE MANURE INTO USEFUL PRODUCTS
7 AUTHOR(S)
Bruce S. Dunn, John D. Mackenzie, and Eugene Tseng
9 Pt R FORMING ORGANIZATION NAME AND ADDRESS
UCLA School of Engineering and Applied Science
Los Angeles, California 90024
5. REPORT DATE
Septcniher 1976 (Issue Date]
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO
10. PROGRAM ELEMENT NO.
1HB617
11. CONTRACT GRANT NO.
R-802933
12. SPONSORING AGENCY NAME AND ADDRESS
Robert S. Kcrr Knvironmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
13. TYPE OF REPORT AND PERIOD COVERED
Final Report (1/74-5/75)
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The purpose of the project was to design and build a pyrolysis apparatus for
cattle manure and to investigate the potential uses of the pyrolysis by-products.
A pyrolysis machine of semi-continuous feed capabilities was designed and built.
Various conditions of pyrolysis treatments were investigated and their influence
on the amount and composition of the by-products determined. High carbon residues
were found to require lower pyrolysis temperatures. The carbon content of these
residues appeared to be unaffected by the geographic location of the original
manure. Contact with interested parties and appropriate industries who could be
prospective users of each of the products was initiated to obtain their technical
expertise in evaluating these products. The pyrolysis by-products seem to have
some potential industrial applications. These by-products include the solid
residue, an oil fraction, and an aqueous fraction. The solid residue may serve
as a carbon black substitute or as a filler material in rubber, ink, and paint.
The aqueous fraction collected during pyrolysis has been evaluated for fertilizer
applications.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Cattle; Agricultural Wastes; Pyrolysis;
By-Products
i.IDENTIFIERS-OPEN ENDEDTERMS
Lampblack, Glass Foam;
Ink; Glass Tile; Rubber;
Briquettes; Oil;
Fertilizer; Paint
.-. COSATI Held/Group
02/A, C, E
<3. DISTRIBUTION STATEMENT
RELEASE UNLIMITED
19. SECURITY CLASS (This Report!
Unclassified
21. NO. OF PAGES
42
20. SECURITY CLASS iThispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-731
34
U S GOVERNMENT PRINTING OFFICE !977-757-056/5<<57 Region No. 5-11
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