SH-2,
Solid Waste Management / Composting
European activity and American potential
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Solid Waste Management / Composting
European activity and American potential
This report (SW-2c) was written for the Solid Wastes Program
by SAMUEL A. HART
University of California, Department of Agricultural Engineering
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Consumer Protection and Environmental Health Service
Environmental Control Administration
Solid Wastes Program
CINCINNATI
1968 IW- Environmental Protection /V:;:r,cy
Region V, Library
230 South Dearborn Street
Chlccgo, Illinois 60604
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2nd printing
1970
Public Health Service Publication No. 1826
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402 - Price GO cents
11,3. Environmental Protection Agency
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Foreword
Reports from Europe have suggested that com-
posting and compost utilization have been more
successful there than in the United States. A
study was therefore made of the status of com-
posting and compost utilization in Germany,
Holland, and Switzerland, and the findings
were related to the solid wastes problem in
America.
Nine compost plants are in operation in
Germany, one-sixth of Holland's domestic
refuse is made into compost, and Switzerland
has an active composting program. Yet, in all
three countries, composting is a very minor
pathway for the disposal of solid wastes, and
there are serious production costs and market-
ing problems. These countries make only as
much compost as can be sold; excess refuse from
the communities is burned or buried. Generally,
compost can be sold only if it is well screened
and of good appearance. The compost is used
almost exclusively in luxury agriculture—bulb
and flower growing, grapes for fine wine pro-
duction, and gardens and parks. There is simply
no market for the compost in basic agriculture.
This same approach to composting has also
been attempted in the past in the United States.
The results have been similar, though even less
successful: The market (in luxury agriculture)
has been smaller, and the cost of producing the
compost has been greater.
There are possibilities, however, for a more
satisfactory program of composting for solid
waste disposal. Rough-quality compost, cheaply
produced, without grinding or fine screening,
has real potential for the reclamation of spoiled
lands (as from mining), for the prevention of
erosion, for reduction of the volume of material
going into a landfill, and as a cover material for
above-grade landfills. A further and even more
favorable avenue of composting practice will be
to consider land as an acceptor of compost rather
than compost as a benefit to the land. Rough-
quality compost might be applied at the max-
imum assimilable rate (perhaps 100 tons per
acre-year) to a piece of land. The land would
not be used for crop production, but neither
would the land be irreparably changed, as with
a landfill or dump. If or when the land becomes
needed for subdivisions or agriculture, the com-
post application could be stopped and the land
would recover.
This report fulfills U.S. Public Health Service
Contract PH 86-67-13. It contains detailed find-
ings of a European survey and proposals for
future American research and practice.
—RICHARD D. VAUGHAN
Chief, Solid Wastes Program
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WEST
Duisburg
GERMANY
Bad K?euznach Schwemfurt
•Heidelberg
Turgi. Hijwil
La Chaux
de Fonds B
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Contents
Introduction, 1
Composting in Proper Perspective, 3
Survey of 14 European Composting Plants, 5
Compost Utilization in Europe, 23
European Research in Compost Manufacture and Use, 25
The Potential for Composting and Compost Utilization in the United States, 33
Recommendations for U.S. Composting Research, 37
Conclusions, 39
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Solid Waste Management / Composting
European activity and American potential
Introduction
Solid waste management in Europe has long
been lauded as a model of efficiency and ap-
propriateness. The argument or explanation has
been that, in densely populated Europe, one sim-
ply must be right about waste mangement—and
the Germans, Swiss, Dutch, and other Euro-
peans are right.
One of the foremost claims has been of the
success of composting—and two examples are
always cited to substantiate the claim. The first
is that eight (recently nine) composting plants
have begun operation in Germany since World
War II, that not one has shut down, and that all
are producing compost to capacity. The second
is the success of composting manufacture and
sale by the VAM (Vuilafvoer Maatschappij, or
Waste Transporting Corp., Amsterdam and Wi-
jster, Holland. That corporation makes 160,000
of the 200,000 tons of municipal compost pro-
duced in that country each year, and some eight
cities and towns, including the capital of Den
Haag (1 million inhabitants), deliver all their
municipal waste to that organization.
These examples and others are correct, and
do point up the success of these European com-
posting activities. Nevertheless, even these suc-
cesses are not unqualified (as will be discussed
later), and their success cannot be transferred
automatically and unequivocally to the Ameri-
can scene. Still, an indepth study of the situation
in Europe may assist understanding what might
be appropriate in the United States.
In 1964, G. J. Kupchick, under a World
Health Organization Fellowship, undertook a
comprehensive study of composting costs in Eu-
rope and Israel.* His analysis of 14 composting
plants, serving a total population of over 3,136,-
000, indicated an average composting cost of
$4.55 per short ton (2,000 pounds) of raw refuse
received. Although the sale price of the com-
pleted compost averaged $2.73 per short ton,
with a maximum price of $5.45 per short ton,
it averaged only $0.90 income per ton of raw ref-
use received by the composting plant. (Salable
compost weight was between 16 and 70 percent
of the weight of the incoming raw refuse, the
loss being due to removal of noncompostables,
moisture loss, and the organic degradation loss
that converts refuse to humus.) The net cost of
composting (with allowance for iron, rag, and
paper salvage, if conducted) amounted to $3.38
per short ton of raw refuse accepted.
It is not the purpose of the present report to
further study the economics of composting. The
fact that such substantial quantities of compost
are produced and utilized in Europe and Israel
makes it appropriate to study some of the factors
related to compost use, and that is the major em-
phasis of this report.
*KUPCHICK, G. J. Economics of composting muni-
cipal refuse in Europe and Israel, with special reference
to possibilities in the U.S.A. Bulletin of the World
Health Organization, 34(5): 798-809, May 1966.
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Composting in Proper Perspective
For many years composting has been considered
a "waste-utilization" activity, and therefore
somehow "good." This is in comparison with
landfilling, burial, and incineration, which have
been thought of as "waste-disposal," and there-
fore not quite so "good." But today there are
planned landfilling operations which are re-
claiming land for future use, and there are a
number of European incinerators which pro-
duce usable steam or electric power from burn-
ing municipal refuse. An appropriate starting
point for more careful analysis of composting
is a new and careful defining of solid waste
management.
Man, especially the modern city man, pro-
duces large amounts of solid waste. If these
wastes are discharged indiscriminately and with-
out control, they degrade the environment in
which man lives. To prevent or minimize deg-
radation of the environment, man must "man-
age" his wastes. This management consists ba-
sically of performing five distinct unit opera-
tions: Collecting; transporting; storing; proc-
essing; discharging.
The first three operations are often repeated
several times in various sequences. For instance,
with domestic refuse the housewife collects and
transports the waste from its point of production
(kitchen sink or wastepaper basket) and stores
it in the garbage can until it is picked up by the
refuse collection agency. In turn, this agency
transports and stores the material—in the truck
or at an intermediate transfer point. The first
three operations together—collecting, trans-
porting, and storing—can be considered the first
step in solid waste management.
"Processing" is the changing, modifying, or
converting of a material. The change can be
physical, chemical, or biochemical. In solid
waste management practice only three basic
procedures are presently available to process
solid waste—incineration, composting, and
burial.
It is easy to see how incineration and com-
posting fit the definition of processing—of
changing or modifying the product. Burial is
also a processing operation, because the waste
is compacted and incorporated into a physical
part of the earth. Even in an open dump, where
the waste is strewn over the land, the waste is,
in an objectionable sense, processed or con-
verted—into flies, rats, smoke, odor, and other
nuisances. These undesirable products are the
result of improper and uncontrolled processing.
"Salvaging," the removal of marketable ma-
terials from the total mass of the refuse, is some-
times practiced in solid waste management. The
picking operation usually occurs during proc-
essing of the main body of waste. In truth, how-
ever, salvage is really a part of the discharge
operation.
The last unit operation in solid waste manage-
ment is "discharge." It has usually been called
"utilization" or "disposal," but, as pointed out
309-7ST O—68
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earlier, this unfairly lauds composting and dep-
recates landfilling or incineration. The more
meaningful impression is conveyed by calling
this last step "discharge—into the environment."
The flue gas from a refuse incinerator is a dis-
charge into the environment. The compost that
the farmer or city park department spreads on
the field or playground is also such a discharge
into the environment. And in the burial of
wastes the "discharge" is the total landfill site,
not the material within the landfill. At some fu-
ture date the landfill will be completed, and the
site will be discharged into the environment, be-
coming available for some other use. Whether
the use is an asset or a liability to the community
depends upon how the refuse was originally
"processed" into the site.
Similarly, the salvage operation returns the
salvaged material into reuse channels, and thus
is also a discharge into the environment.
This concept of solid waste management at-
tributes no special merit to one system of proc-
essing over another. Composting is basically no
different from other processing techniques. It is
preferred when it is the most economical sys-
tem, or when the "discharge into the environ-
ment" via composting is less detrimental than
the discharge from other processing methods,
and if society is willing to pay the additional
price for the lesser insult to the environment.
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Survey of 14 European Composting Plants
This study of European composting activity was
primarily concerned with utilization of com-
post after manufacture. In the pursuit of this
goal, 14 European composting plants were vis-
ited. In addition to learning how these plants
dispose of their compost, information was ob-
tained on their composting equipment, facilities,
and procedures. A brief description of the opera-
tion of the plants is interesting in itself, and
adds to the understanding of composting as a
method of solid waste management.
The composting plants that were visited are
indicated in figure 1.
Composting is more applicable to a city's do-
FIGURE 1. Locations of composting plants visited in the
course of this study. Major cities (Paris, Den Haag,
Hamburg, Hannover, Frankfurt, and Munich) do
not have composting plants but are indicated for
orientation purposes.
mestic refuse than to commercial or industrial
refuse, and composting is not generally appro-
priate to debris from construction and demoli-
tion. Thus, most European composting plants
accept only domestic refuse and have alternate
or supplementary facilities for handling the non-
compostable parts of commercial and industrial
refuse. Even with domestic refuse, a considerable
percentage (15 to 30 percent by weight) is not
compostable and must be removed before the
compost can be sold or used. The details of this
process and others are best explained as they
apply to individual plants.
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FIGURE 2. Model of Dano composting drum at Bad
Kreuznach (and also at Duisburg and Hinwill).
FIGURE 3. Exterior of compost building. Bales of com-
pressed tin cans are lined against the wall at the left.
Bad Kreuznach, Germany
Population served, 45,000
Type of plant, Dano
One of the most successful composting opera-
tions in Europe is at Bad Kreuznach. This city,
near the center of the Riesling wine area, is on
the Nahe River, a tributary of the Rhine. Much
of the vineyard acreage of the area is on steep
hillsides, where added organic matter is needed
to prevent excessive soil erosion. Manures and
similar organic materials have been in short sup-
ply in the Bad Kreuznach area. Thus, in 1958
the BVB (Bodenverbesserungverband, or Soil
Improvement Cooperative) of the local grape
farmers (under the leadership of its president,
Mr. O. Andres) entered an agreement with the
city and the state. The compost plant, belonging
to the farmer cooperative, was built on city land
adjacent to the sewage treatment plant. The
city's public works department collects and hauls
domestic refuse to the compost plant, where it
is discharged into the composting drum. The
city pays DM 80,000 (about $20,000) per year for
this dumping privilege, which is less than the
cost of hauling the waste to a more distant land-
fill and burying it. (The landfill is used for com-
mercial and industrial wastes, except winery
wastes.) Sewage sludge from the adjacent plant
can be and has been incorporated into the com-
post, but at present it is hauled away as liquid
sludge by the farmers and used in that form.
The unground, raw domestic refuse brought
to the composting plant, along with raw winery
wastes in winter (the lees, or skins, seeds, and
stems), is put into the Dano drum. Residence
time there is 3 to 4 days. The partially com-
posted material is then removed from the drum.
Iron is removed with a magnet, and the compost
is sieved. The compost is then piled into wind-
rows for curing and storage until purchased by
the farmer—in the fall of the year. Thus, some
compost is stored 9 or 10 months. The noncom-
postable material—"scalpings" from the sieve—
are used for fill material at the compost site.
(The plant was located on low-lying ground,
and the approximately 10-acre compost storage
site has been raised about 6 feet in 10 years of
operation.)
About 8,000 cubic meters (10,500 cubic yards)
of compost are manufactured each year from
the incoming 25,000 cubic meters (33,000 cubic
yards) of raw domestic refuse. The compost is
sold to the Cooperative members for DM 10 per
cubic meter ($1.90 per cubic yard), f.o.b. the
compost plant. This revenue of DM 80,000
($20,000), plus the city's payment of DM 80,000
($20,000), just equals the cost of making the
compost (labor, maintenance, and equipment
amortization).
The state's contribution to this venture has
been to furnish a part of the capital and to pay
the salary of a research scientist attached to the
operation. These research scientists (formerly
Dr. H. }. Banse, now Dr. I. Bosse) have done
research on the composting operation itself and
on compost utilization. The compost utilization
research has consisted of measuring runoff wa-
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FIGURE 4. Interior view of building.
FIGURE 5. Curing yard (on a frosty morning).
ter and runoff soil from some steep experimental
plots. (This is discussed on page 28 with
the German research.) The success of the Bad
Kreuznach composting operation is due to all
the above factors—economy to the city, state
support, and, most important, a good market
for the compost. All factors may well be re-
quired for similar American success.
Blctubeuren, Germany
Population served, 20,000
Type of plant, windrowing of shredded refuse
Blaubeuren is a small community in the Alb
Mountains of Germany. A large cement plant in
the city uses the calcareous rock of the surround-
ing area as raw material for cement manufac-
ture. Dr. E. Spohn, mill manager and part
owner, has long believed in returning the ore-
stripped land to agricultural productivity and
has advocated and been demonstrating the value
of compost from municipal waste for this
reclamation.
Blaubeuren does not produce enough com-
post to reclaim the land at the rate it is being
consumed, composting is rather expensive for
such a small community, and no tangible, direct
measure of the value of land reclamation is yet
available; still, the concept of this reclamation
and the idealism of Dr. Spohn are highly com-
mendable. Not only is Dr. Spohn personally
knowledgeable in composting technology, but
he has equipped his cement manufacturing op-
eration with a research laboratory and an experi-
mental farm for the purpose of studying this
special field of compost utilization. Hopefully,
his ideas and findings will develop into a new
avenue of compost utilization.
The Blaubeuren compost plant itself is small
and unpretentious. The incoming raw domestic
refuse is run through a Dorr-Oliver rasper. Burn-
able uncompostable refuse is disposed of in a
simple incinerator. The raw rasped refuse is
piled into windrows and cured, with one or two
turnings in 3 to 6 months. Most of it is then used
in the land reclamation research discussed above.
Sewage sludge is sometimes added to the ground
refuse before it is put into windrows, but, since
the sewage treatment plant is some distance
away, the sludge (cake or slurry) must be
trucked in.
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FIGURE 6. Blaubeuren compost plant with freshly FIGURE 7. Windrow of cured, ready-to-use compost.
ground refuse ready for composting.
Duisbwrg-Hwc\ingen, Germany
Population served, 90,000
Type of plant, Dano
Duisburg is a major industrial city on the west-
ern end of the Ruhr River. The city had been
having trouble with sewage sludge disposal and
decided that composting domestic refuse plus
sludge could be economical and satisfactory.
Therefore, a two-drum Dano plant was built
at one of the sewage treatment plants, and refuse
from 90,000 of the 400,000 inhabitants is con-
verted into compost.
Incoming raw refuse is handpicked for glass
and rag salvage, and iron is removed by a mag-
net. The refuse, otherwise untreated, is then put
into the 11-foot-diameter 60-foot-long Dano
drums, along with sewage sludge, and tumbled
for 3 to 5 days. The fresh compost is sieved and
piled outside to cure. The noncompostable sieve
scalpings are buried.
This plant _has had trouble with odors from
the composting operation. The plant, once in
an undeveloped area, is now surrounded by up-
per-middle-class apartments. At one time, odors
from composting (anaerobic conditions within
the Dano drum) were so objectionable that the
plant had to be shut down in summer when the
incoming refuse was wettest. (In winter there
are fewer vegetable and garden trimmings, and
the ash content is higher.) The odor problem
has been solved by a combination of techniques.
First, the sewage sludge is thickened or partially
dried to add a minimum of moisture to the sys-
tem. Even then, only one-third of the popula-
tion equivalent of sludge can be added in sum-
mer, and one-half the population equivalent is
added in winter. In addition all the exhaust
ventilation air of the building and of the Dano
drums is scrubbed through a soil filter. This
filter consists of a buried perforated pipe covered
with earth and cured compost; the filter, ap-
proximately 10,000 square feet in size, filters
about 7,000 cubic feet of air per minute.
The cured compost is usually rescreened, and
may be ground or crushed and sieved again,
resulting in a fine-textured, homogeneous, ac-
ceptable compost. It is sold primarily for gar-
dening, nursery, and landscaping use, with none
going to general agriculture. The selling price
was reported to be DM 5 per metric ton ($1.15
per short ton), and 8,000 to 10,000 metric tons
(9,000 to 11,000 short tons) are made per year.
It is interesting that over three-quarters of
Duisburg's domestic refuse, plus all the com-
mercial and industrial refuse, is handled other
than by composting. At present this refuse is
being landfilled, but Duisburg is presently plan-
ning an incinerator with power generation. The
plant engineer felt that the composting opera-
tion will probably be no more expensive than
incineration, and that compost will continue to
be manufactured as long as there is a market
for it.
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FIGURE 8. Blaubeuren research field on mined-over
land.
FIGURE 9. Laboratory plots on compost utilization.
Heidelberg, Germany
Population served, 30,000
Type of plant, Multi-Bactor compost tower
Heidelberg is the world-famous university
city in southwest Germany. The city and its
environs contain about 160,000 residents, includ-
ing some 5,000 U.S. servicemen with families.
Twelve years ago city engineer O. Horstmann
began investigating composting as a method of
processing the city's domestic refuse. The first
idea was to sort, rasp, and ballistically separate
the refuse and then place it in large windrows
(about 35 feet wide and 20 feet high). Anaero-
bic conditions within the windrows caused foul
odors, and it was difficult to turn the windrows.
In 1962, therefore, a mechanical composting
tower, the Earp-Thomas Multi-Bactor unit was
installed and is working satisfactorily. Today
this unit is making about 2,000 cubic meters
(2,600 cubic yards) of compost per year.
Sewage sludge is added to the Door-Oliver
rasped refuse and conveyed to the tpp of the
eight-stage 20-foot-diameter 35-foot-high com-
posting tower. A vertical shaft turns plows on
each stage. The refuse is thus stirred continually,
and it gradually drops from stage to stage
through holes in each stage. The shaft and
plows operate 8 hours per day, and the refuse
FIGURE 10. Duisburg-Huckingen compost building.
Air exhaust mechanism is at rear of building.
FIGURE 11. Hand salvaging of glass and rags. One of
the two Dano drums is in the background.
FIGURE 12. Baling of the salvaged metal.
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FIGURE 13. Heidelberg Multi-Bactor composting tower.
FIGURE 14. Compost storage at Heidelberg.
residence time within the tower is 3 days. The
removed compost is sieved, and dropped onto an
impact separator known as a secator. Glass, slag,
and hard objects bounce one way, while the
high-quality and softer compost rolls the op-
posite way. The compost is stockpiled tem-
porarily, until it is taken away by the whole-
saler, but longtime curing does not appear to
be necessary.
The wholesaler pays DM 13 per cubic meter
(about $2.50 per cubic yard) for the compost.
He arranges to sell and transport it, and some-
times even to apply it. Essentially all of the com-
post is used for home gardens and landscaping
projects. The wholesaler does dispose of all the
2,000 cubic meters (2,600 cubic yards) per year,
but that appears to be the limit of the market
although Heidelberg could make more compost
by processing more of the city's domestic refuse.
FIGURE 15. Schweinfurt composting plant. Piles in
foreground are ground compost awaiting shipment.
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Schweinfurt, Germany
Population served, 85,000
Type of plant, Caspari-Brikollare
FIGURE 16. Interior of compost briquetting building.
A new process, the "Brikollare Verfahren," or
briquette process, is used to make compost at a
plant erected in Schweinfurt in 1965. Previously,
all municipal solid wastes, including industrial
waste from two large ball-bearing manufac-
turers and one heavy-machinery fabricator, were
buried in a landfill. That was changed with the
construction of a $1,000,000 composting plant
for domestic and commercial waste and a
f 1,250,000 incinerator for industrial waste.
The incoming domestic and commercial ref-
use is elevated from the receiving bunker by a
belt conveyor. One man inspects the refuse as it
is conveyed and removes materials that might
damage the mechanisms, but he does not really
salvage any material. Iron is removed by a mag-
netic separator, and then the refuse falls into
Dorr-Oliver raspers for shredding. The shredded
refuse is then run through a ballistic separator,
where gravel, broken glass, and similar hard,
heavy material is removed. The ground com-
postable refuse is then elevated to a surge tank.
Meanwhile, digested sewage sludge from the
city's treatment plant is vacuum filtered to in-
crease the solids content from 12 to 30 per-
cent (nearly three-quarters of the water in the
sludge is removed). The dewatered sludge is
mixed with the ground refuse in an auger con-
veyor and conveyed to the briquetting machine.
Here, an elaborate machine produces briquettes,
approximately 15 inches by 9 inches by 6 inches
in size, that have a "tunnel" on the underside.
These are placed automatically on pallets that
are moved to a "curing shed," where the actual
composting takes place. The briquettes quickly
heat to 130° to 140° F (55° to 60° C), a surface
fungal growth develops, and the briquettes both
dry out and compost. The salient feature of the
process is this concurrent biological-physical
change. The metabolic heat of composting pro-
motes surface drying, while the compacted na-
ture of the refuse caused by the pressing of the
briquettes allows capillary transfer of moisture
from the center to the surface. Concurrently, as
moisture is removed, air enters the capillaries
of the briquette and sustains the aerobic fungal
and bacterial organisms that attack the refuse
and convert it to compost. The close stacking of
the individual briquettes, along with their tun-
nel form, gives adequate opportunity for air
transfer while still conserving the heat of com-
posting. Even the outside-corner briquettes at-
tain a temperature of 120° to 130° F (50° to
55° C). In the curing process the moisture con-
tent drops from about 65 to about 13 percent
(wet weight basis).
The cured briquettes are stacked outside in
a yard like normal building bricks. In the fall
of the year, when compost can be marketed to
nearby grape farmers, the briquettes are run
through a simple hammermill, and the finished
compost is sold.
The impressive features of this Caspari proc-
ess are the odor-free operation of the biological-
309-787 O—68
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FIGURE 17. Closeup of briquetting machine.
FIGURE 18. Briquettes stacked on a pallet in the curing
physical composting process and the minimal
land area that is needed. Additionally, the
vacuum filtration of the sewage sludge makes
possible the disposal of both domestic refuse and
sewage sludge. Some 10,000 metric tons (11,000
short tons) of compost are produced each
year. At the beginning the selling price for the
compost was pegged at DM 17 to 20 per metric
ton ($3.85 to 4.50 per English ton), but the price
was recently reduced to DM 8 per ton ($1.80
per English ton), and the market for compost
was improved.
Compost made by this new process is of good
quality, but probably is no better or worse than
compost made by any other process. The quality
of compost depends upon how much grinding,
screening, sieving, ballistic separating, and simi-
lar physical upgrading are done. This upgrad-
ing can be done after composting, as in the Dano
process, or before, as in the Caspari. Probably
neither process offers any great economy over
the other. The Schweinfurt operation appears
to be quite economical of labor, but amortiza-
tion of the large capital investment is a signifi-
cant cost.
St. Georgen, Germany
Population served, 14,000
Type of plant, windrow of ground refuse
St. Georgen is a small spa, or resort town, in the
Black Forest, southwest of Stuttgart. The city's
small compost plant takes the community's do-
mestic and commercial waste (there is no indus-
try other than tourist) plus sewage sludge, and
converts it into compost. The refuse is hand-
picked for salvageable items, iron is removed
by a magnetic separator, and the refuse is ground
with a Biihler hammermill. Noncompostable
material (mostly commercial refuse) is burned
a 1.5-metric-ton-per-hour (1.65-short-ton-
m
per-hour) incinerator, and the ash is returned
to the freshly ground refuse. This refuse, plus
sewage sludge from the adjacent sewage treat-
ment plant, is arranged in windrows (about 10
feet wide and 4 feet high) and cured for 3 to 6
months, usually .with three turnings.
About 1,400 cubic meters (1,800 cubic yards)
of finished compost are produced each year, and
sold at DM 10 per cubic meter ($1.90 per cubic
yard) to home gardeners, truck-crop farmers,
and forestry nurseries. The net cost to the city
was not reported, but would appear to be rather
high because of the small volume of waste han-
dled plus the investments in both incinerator
and composting equipment. The plant is neat
and well-run.
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FIGURE 19. Outside storage of the composted briquettes,
awaiting final grinding and sale.
FIGURE 20. St. Georgen composting plant and
sewage treatment plant.
FIGURE 21. Windrow curing of St. Georgen
compost.
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FIGURE 22. Stuttgart Mohringen composting plant.
Stuttgart (the suburb of
Mohringen), Germany
Population served, 75,000
Type of plant, windrow of ground refuse
The Stuttgart composting operation is similar
in concept to those of Duisberg and Heidelberg.
That is, public works officials recognized that
composting was a feasible avenue of manage-
ment for a portion of the city's domestic refuse,
though not for all of it (Stuttgart is a city of
650,000). Therefore, a conventional windrow
composting plant was built in 1959 in the subur-
ban district of Mohringen. This plant is the
only one in Germany that was not conceived to
take sewage sludge also. The incoming refuse
is conveyed from the storage bunker over a pick-
ing belt. When salvage prices are favorable,
glass, cardboard, clean paper, or rags can be
picked off. At present only iron is removed with
FIGURE 23. Curing or compost in closely packed
windrows.
an overhand electromagnet. The refuse goes to
a Dorr-Oliver rasper and is abraded. It is then
transported by truck some 50 to 100 yards to the
windrow area, where composting occurs. The
material is turned twice within about 3 months.
There has been no high-pressure selling pro-
gram to dispose of the compost. Citizens of
Stuttgart may come to the plant and take, at no
charge, small amounts of the material for their
homes and gardens. Most of the compost, how-
ever, is sold to neighboring grape farmers for
about DM 5 per metric ton ($1.15 per short ton).
Composting is looked upon at Stuttgart as a
public service, not only to satisfy homeowner
wants but also to demonstrate the principle of
conservation. It is recognized and accepted by
the city government that composting costs more
than alternative waste disposal methods but that
it is an appropriate community expenditure, the
same as supporting city parks or museums.
14
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Versailles, France
Population served, 82,000
Type of plant, Triga, silo type
The composting plant in Versailles (near Paris)
is brand new. Regrettably, not many details
were available—mostly because of language
difficulties. It was inspected as a part of attend-
ance at the INTAPUC (International Associa-
tion of Public Cleansing) Conference held in
Paris in June 1967.
Incoming domestic refuse amounts to some
150 metric tons (165 short tons) per day. The
metal is removed with a magnetic separator,
and the refuse is then ground with a heavy-duty
Hazemag hammermill. The ground refuse is
rough screened (scalpings go to an incinerator)
and then put into the four silos, each with a
capacity of 320 metric tons—about 700 cubic
meters (350 English tons—915 cubic yards). It
FIGURE 25. The actual plant.
was unclear whether the daily input is divided
among the four silos or whether one silo is used
for each day's waste, in rotation. In any event,
some air is blown through the silo for aeration,
and each silo is equipped with a bottom unload-
ing device. The removed compost is sieved a
second time and then piled outside for curing
and to await sale.
This plant, evidently privately owned (by the
Triga Co.), charges the city of Versailles 4 FR
per metric ton (about $0.73 per short ton)
for domestic waste accepted. (This seems very
low and appears to be a promotional price
which does not reflect the actual cost of waste
disposal.) The price and the market for the
finished compost were not defined. The plant is
new, and perhaps the market has not yet
developed.
The plant is very attractive and is apparently
a well-engineered unit.
FIGURE 24. Model of the
composting plant
at Versailles, France.
15
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FIGURE 26. Composting plant at Buchs, Switzerland. A
new incinerator building is being constructed adja-
cent to the compost building.
FIGURE 27. Biihler mill for grinding the refuse.
Bucks, Switzerland
Population served, 40,000
Type of plant, windrow of ground refuse
•
The Buchs compost and waste-burning plant in
Switzerland serves some 40,000 people in 16
communities in two countries (Switzerland
and Lichtenstein). The actual plant is located
in the town of Buchs, population 5,000. Domes-
tic refuse is brought to the plant by municipal
vehicles of the various communities. (Commer-
cial and industrial refuse and construction debris
are hauled to a regional landfill.) Both the mar-
ket for compost and the facilities of the com-
posting plant are not adequate for all the re-
ceived refuse to be converted to compost, so a
substantial fraction is burned in open piles—
with concomitant smoke and nuisance. A new
incinerator is presently being constructed,
and it is expected that the majority of the do-
mestic refuse received by the plant will then be
burned. Composting will be continued to the
extent of its marketability—primarily to grape-
growers in the area.
The incoming refuse is first ground with a
Biihler coarse hammermill. Iron is then re-
moved with a magnetic pulley, and the refuse
falls into a second hammermill for fine grind-
ing. The refuse is then sieved. (Scalpings are
buried in the industrial-waste landfill site.) Sew-
age sludge can be and is mixed with the sieved,
freshly ground refuse, and the material is then
placed in windrows, which are usually turned
twice during the following 4 months.
No really valid idea was developed of the
communities' needs for composting and the
costs and marketability of compost there. The
demand, however, did not seem very great.
FIGURE 28. Ground refuse at the beginning of com-
posting.
FIGURE 29. Compost windrows at Buchs-
16
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FIGURE 30. Hinwill, Switzerland, composting plant.
Vapor coming from piles is primarily snowfall onto
the warm compost.
Hinwill, Switzerland
Population served, 100,000, in 23
surrounding communities
Type of plant, Dano
Like most Swiss plants, the Hinwill compost-
ing plant serves a number of small communities,
Hinwill itself has a population of 3,500. Thus,
the wastes are primarily of domestic origin, with
only a small volume of commercial and indus-
trial refuse needing disposal. The incoming
refuse is run over a magnetic pulley and de-
posited in the Dano drum along with thickened
sewage sludge. The drum itself is 11.5 feet in
diameter by 90 feet long, and the refuse has a
residence time of 2 to 3 days. The discharged
material is run through a coarse and a fine Biih-
ler hammermill, sieved, and then stored outside
for final curing. The material not passing
through the sieve is burned on site. This incin-
erator is too small and has created some opera-
tional problems. As at the Dano plant in Duis-
burg, a soil filter system for the ventilation air
had been installed and appeared most success-
ful. The compost is sold primarily for grape
vineyards, but the marketing situation did not
seem good. It appears that lack of demand for
compost is the stumbling block to Swiss success
in composting.
FIGURE 31. View along the Dano drum.
FIGURE 32. Soil filter for removing odors from the ex-
haust air.
17
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FIGURE 33. Composting plant at La Chaux-de-Fonds,
Switzerland. Building on left, and compost windrow
on right.
FIGURE 34. Dano Egsetor part of the compost prepa-
ration equipment.
La Chaux'de'Fonds, Switzerland
Population served, 15,000 (estimated)
Type of plant, original Dano
(built in 1953)
This plant is located in the western (French-
speaking) section of Switzerland, in the city
of La Chaux-de-Fonds, population 43,000. The
plant is one of the original Dano installations,
with a fast-rotating drum followed by a drum
screen. The incoming domestic and commer-
cial refuse from about one-third of the city is
put into the conventional Dano drum (at La
Chaux-de-Fonds it is about 9 feet in diameter
and 40 feet long). The drum is rotated at about
2 rpm for a half hour, to abrade, crush, and
FIGURE 35. Interior of the Egsetor showing the pipe
screen which holds back the noncompostables.
grind the refuse. The material is then conveyed
to a drum screen, called an Egsetor. This unit
is 9 feet in diameter and 12 feet long. An outer
shell and an inner cage or sieve of pipes rotates;
the crushed, ground, fine material falls through
the pipes while cans, plastic, and large inert
materials are retained on the pipe screen. The
two components are periodically removed from
the Egsetor to separate piles, the compostable
refuse is skip loaded to a windrow, and the
inerts are buried.
Presently the compost is being sold to small
truck-crop farmers in the area or transported
30 or more miles for home-garden sales. The
plant is old, and the compost market is poor,
so that this composting operation will probably
be shut down before long.
FIGURE 36. Elevator and diverting chute for noncom-
postable discard material (center) and refuse for
composting (right).
18
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FIGURE 37. Composting plant building at Turgi,
Switzerland.
FIGURE 38. Schematic drawing of the composting plant.
Turgi., Switzerland
Population served, 70,000, in 10 communities
Turgi population 5,000
Type of plant, Multi-Bactor compost tower
This plant is similar to the Heidelberg Multi-
Bacto composting operation except that it is
enclosed within a building and uses different
makes of auxiliary equipment. At the time of
the visit one of the composting towers was out
of operation for replacement of the plows that
mix and move the refuse.
After iron is removed magnetically, the
refuse is ground with a Hazemag hammermill
and then sieved before being elevated to the
Multi-Bactor tower. After residence in the
tower, the compost is sieved again and prepared
for market. No curing is provided. A consider-
able volume of the Turgi compost is put into
heavy-duty plastic sacks for sale to homeown-
ers. It appeared that less than half of the incom-
ing refuse is made into compost, the division
being made on the screen after the grinding.
The grinding of the raw refuse reduces volume
greatly, so that it can be landfilled more easily.
Despite the repairs to keep the plant in opera-
tion for a few years more, the decision has been
made to incinerate refuse in the future. A large
two-furnace incinerator installation will be built
adjacent to the present compost plant. Burnable
industrial and commercial refuse, as well as
domestic refuse, will then be handled by the
incinerator plant. The composting operation
will probably continue to the extent that com-
post can be sold at a price that defrays the extra
costs of composting over incineration.
FIGURE 39. View of the top of the Multi-Bactor
composting tower.
19
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FIGURE 40. Aerial view of the compost plant at
Arnhem, Holland.
FIGURE 41. Pivoting belt conveyor to distribute fresh-
ground refuse into circular windrows.
Arnfoem, Holland
Population served, 134,000
Type of plant, Windrow, of ground refuse
Composting is much more successful in Hol-
land than in Switzerland, because compost
utilization is more highly developed. Thus,
plants like that at Arnhem are models of pro-
ductiveness, efficiency, and cleanliness. The in-
coming domestic and compostable commercial
and industrial wastes are run over a magnet for
iron removal, and then shredded in a Dorr-
Oliver rasping machine. The unshredded ma-
terial from the rasp, plus burnable bulky objects
and noncompostable industrial waste, is burned
in an onsite incinerator (an operation similar to
that at Schweinfurt).
The shredded refuse from the rasping ma-
chine is placed in concentric windrows by a
pivoting belt conveyor. The engineers at Arn-
hem are presently experimenting with remov-
ing plastic film from the freshly ground refuse
by means of an air blast that blows it out while
the refuse falls from one belt to another. This
apparently holds promise but is far from being
fully worked out.
Not all the freshly placed refuse is allowed to
cure at the compost plant. At some periods of
the year nearly all of the freshly ground refuse
is bought by specialty farmers in the area and
used in hotbeds. Like horse manure of old, this
freshly ground refuse undergoes biological sta-
bilization, producing heat and keeping the
plant-bed warm.
Freshly placed refuse that is not sold im-
mediately is piled into windrows about 4 or 5
feet high. After the initial heating the windrow
is turned and piled higher, into a windrow 12
or 15 feet high, and curing is continued.
The compost is not sold directly by the City of
Arnhem, but by the VAM organization. The
officials at Arnhem calculate that the city's do-
mestic refuse could be disposed of by dumping
or landfilling at a cost of f 2.50 (about $0.75)
per capita per year. Composting net costs are
higher, about f 3 (about $0.90). The govern-
ment and the citizens approve of this greater
expense on the basis of pollution control, con-
servation of resources, and long-term esthetic
benefit to the country.
20
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FIGURE 42. Discharge end of pivoting belt conveyor.
Wijster, Holland
Population served, 1 million plus: Den Haag
and other communities
Type of plant, Van Maanen system
The Wijster compost plant, owned and oper-
ated by the VAM, is in the heath area of north-
western Holland, about 90 miles from Den
Haag, source of most of the refuse. Composting
has been conducted at Wijster since 1927. Do-
mestic and commercial refuse, plus some indus-
trial waste, is transported to Wijster by special
railroad cars from Den Haag and the other con-
tracting cities. The railroad cars are unloaded
by gravity from viaducts above the composting
area. The untreated refuse is wetted down with a
sprinkler system and allowed to begin compost-
ing. After 1 or 2 months the refuse is turned
with large grab cranes, with two or three turn-
ings being made during the composting period
of 6 to 8 months. When the composting is com-
FIGURE 43. Garbage transfer station at Den Haag,
Holland. The special railroad cars are in the back-
ground.
pleted, the refuse is conveyed into the processing
plant by cable-operated railroad cars. At the
plant the refuse is sieved, crushed, and resieved.
Several grades of compost are manufactured, in-
cluding some with peat moss added. The non-
composted residue is transported to an open-
dump disposal site, where it is distributed and
compacted. This is not objectionable, since the
material is the inert residue from composting.
There are some vector problems at the actual
compost site: rats and flies are attracted by the
freshly placed refuse. The Wijster area is rel-
atively uninhabited, however, and aside from
the vector problem the composting operation as
a whole seems very satisfactory.
Den Haag is presently constructing a large in-
cinerator with power-generation facilities and
will no longer ship raw garbage to Wijster. The
VAM organization has therefore signed con-
tracts with other, smaller cities and will prob-
ably continue to produce nearly as much
compost as previously.
21
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FIGURE 44. Loading of the railroad cars.
FIGURE 46. Unloading of the railroad cars.
FIGURE 48. Cranes used for turning the refuse for
faster and better composting.
FIGURE 49. The composting windrow at Wijster.
FIGURE 45. Overview of the composting plant at
Wijster, Holland, which receives Den Haag's and
other cities' garbage. Note railroad cars on elevated
viaduct.
FIGURE 47. Sprinkling of the freshly unloaded
garbage.
22
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Compost Utilisation in Europe
The theme of this section has been introduced
in the discussions of the individual composting
plants. More detailed discussion is required,
however, since the subject is so important to
any future decisions on composting in the
United States.
The nine composting plants of West Ger-
many make compost from less than 1 percent of
the domestic refuse generated in that country.
The situation is more favorable in Holland,
where one-sixth (17 percent) of the nation's ref-
use is made into compost. France, Switzerland,
and Italy also compost domestic refuse, but the
quantity or percentage figure is not available. All
countries could produce more compost, and
would produce it if it could be marketed and
utilized. At least in Germany, Holland, Switzer-
land, and France, however, expansion of com-
posting operations is slow because there is little
additional opportunity to utilize the compost
economically. (The present emphasis in solid
wastes processing in those countries is on
incineration, with the production of steam or
electricity.)
Compost has its major market only in luxury
agriculture. It is not used extensively in general,
normal, or basic agriculture, and does not seem
to be economically marketable there. In 1927
the Dutch located the composting plant for the
Den Haag refuse 90 miles away, in Wijster, in
the middle of die heath lands. The intent was to
reclaim this sandy, marginal land with compost.
In the early years the compost was distrib-
uted to the nearby land, and some improve-
ment was brought about. But farmers today
have learned to farm with chemical fertilizers.
Organic material is not an important factor ex-
cept for erosion control on steep slopes. Today,
most of Wijster's compost is backhauled to the
populous, intensively cultivated coastal region
of Holland and used in luxury agriculture. The
actual market for Dutch compost in 2 recent
years has been tabulated (table 1).
TABLE 1. SALES DISTRIBUTION OF COMPOST FROM
MUNICIPAL REFUSE IN HOLLAND
Year
Outlet
1961 1965
Forestland improvement . 2.4
Basic agriculture (field and row crops,
and for pig litter) 34. 4
Fruit farming 6. 5
Hotbed vegetable farming* 11.6
Greenhouse vegetable farming 7. 9
Flower and flower bulb production
(greenhouse and outdoor) 11. 7
City park, sportfield, and recreational
25.5
use.
0.6
16.4
6.3
13.0
8.4
17.6
37.7
*Hotbed compost is freshly ground domestic
refuse. It is used on the bottom of the hotbed
in place of horse manure. The biological proc-
ess of composting generates heat that makes
the hotbed crop grow. Hotbed crops in
Holland are cucumbers, melons, and green
peppers.
23
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In Germany too, the marketing of compost
is luxury oriented. About 60 percent of the com-
post is used to reduce or prevent soil erosion on
steep hillside vineyards that produce the grapes
for Germany's fine-quality wines. Although
some people consider wine a basic food, the vine-
yards in southwest Germany on which the com-
post is used primarily produce wines that are
used for social drinking. Organic matter has
always been needed on these hillsides; in former
years the farmers used animal manures and crop
residues. Today, such organic materials are less
available in the immediate area, because of the
mechanization and specialization of agricul-
ture, and the substitute is compost from muni-
cipal refuse.
Most of the rest of German compost is
marketed for home gardens, park and recrea-
tion uses, via similar luxury avenues. There
is, of course, nothing wrong with this—it is
actually a very good thing that man's wastes can
be converted to give him pleasure; but the size
of the market for compost used this way is
strictly limited. The average German citizen
produces about 500 pounds of domestic refuse
per year; between 150 and 200 pounds of com-
post can be made from this amount of refuse.
Utilization of 150 pounds of compost per citizen
per year in luxury agriculture—or in all agri-
culture—seems unlikely. Other markets for
compost are limited.
The Blaubeuren compost plant makes 1,500
to 2,000 short tons of compost per year, it is
being used for mineland reclamation. It was
also indicated that in some years some German
compost is used for fruit production (cherries,
peaches, and fresh grapes) and for market veg-
etables, but no information was obtained on the
actual quantity so used.
The Swiss utilization of compost is similar.
Most of it is used on vineyards, but marketability
has been poor. Attempts to move into the home-
garden market have met with some success, but,
here too, the volume that can be moved via this
avenue is limited. Two of the four visited
plants—Buchs and Turgi—have plans to install
or are installing refuse incinerators and in the
future will produce compost only to the extent
that it is readily marketed.
There has been a good deal of research on
compost utilization in basic agriculture, as dis-
cussed in the next section. The point here, how-
ever, is that, even with promotional research,
compost is not being used extensively in basic
agriculture.
This is regrettable, for compost could be quite
cheaply produced for this use. It would not need
to be so refined, with fine sieving, milling, and
grinding. Yet, compost is not used in basic agri-
culture. The reason is that it does not pay. The
nutrients in a ton of compost are almost negli-
gible; a typical compost contains only 0.5 per-
cent nitrogen, 0.4 percent phosphorus, and 0.2
percent potassium. Farmers can buy and apply
chemical fertilizers more cheaply than they can
apply "free" compost or even livestock manure.
Advocates of compost point out that the im-
portant aspect of compost is the organic matter
content, not the nutrients. It is the organic mat-
ter that improves the physical properties of the
soil, so important in reducing or eliminating
erosion on the steep vineyard slopes. In general
agriculture, however, soil erosion is prevented
more economically with contour farming and
similar practices than with compost addition.
Under today's economic conditions a farmer of
corn, cotton, or general row crops just cannot
justify the use of compost.
In summary, then, compost utilization today
in Europe and the United States is limited to
luxury agriculture. A later section of this report
proposes a new avenue of approach, based on
nonbeneficial utilization. This will probably be
the real future for compost use.
24
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European Research in Compost Manufacture and Use
A number of lines of research in composting
have been conducted in Germany in recent
years. Similar work done in the other European
countries was not investigated during this study.
German composting research has been in such
diverse fields as engineering technology (Stutt-
gart), public health and pathogen survival
(Giessen), use in strip minefield reclamation
(Bonn), use in vineyards (Bad Kreuznach), and
use in general agriculture (Braunschweig).
Engineering Technology—Stuttgart. The
European leader in the engineering aspects of
solid waste management has been Dr. F. Popel,
professor of sanitary engineering at the Univer-
sity of Stuttgart. A part of the research effort
of his Institute and of his personal work has been
in composting technology. This has encom-
passed both basic studies on biological processes
of composting and practical research in design-
ing composting plants for municipalities.
Professor Popel has long felt that the compost-
ing process could be substantially accelerated
and made more economical if partially com-
posted refuse were recycled. The concept is
similar to the activated sludge process of sewage
treatment. Laboratory results at Professor
Popel's institute have proved the merit of this
approach. Actually, the biological process is but
one part of producing compost. The materials-
handling part is equally important, especially
with regard to the removal of noncompostables
and grinding and fine-sieving to meet today's
market. Professor Popel has also been concerned
with this, but lack of support for graduate stu-
dents has limited recent activity in this area. It
is interesting to note, however, that the Caspari-
Brikollare process of composting at Schweinfurt
is an outgrowth of earlier research on materials
handling by Professor Popel.
Although Professor Popel's philosophy and
approach are very important, it appears that the
more critical part of the composting problem to-
day is utilization. Consequently, no indepth
study was made of Professor Popel's activities.
Public Health Problems With Compost—
Giessen. The Institutes of Human Health Pro-
tection and Animal Health Protection of the
Justus Liebig University at Giessen have made
an important contribution to knowledge on
composting and pathogen carryover. Giessen
research is the basis for present German regu-
lations on health hazards from the use of com-
post-sludge mixtures. Since public health prob-
lems will be of concern if compost is used in
the United States on a major scale, it is appro-
priate to describe the German work in some
detail.
In order to prove the positive killing of patho-
genic organisms by composting, the raw refuse
must be known to contain them. But finding
a few residual living microorganisms in a large
sample after composting is like testing for E. coli
in treated water—a particular grab sample may
or may not contain the organism. Multiple
25
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samples and "most probable number" (MEN)
statistics are therefore used in water testing. For
pathogenicity tests with compost, such nega-
tively oriented procedures are inappropriate.
Rather, from an artifiically implanted known
number of pathogenic organisms, one must de-
termine how many are recovered at various
stages of composting. Dr. D. Strauch of the
Institute of Health and Infectious Diseases of
Animals has done exactly this by means of an
"inoculated bag" technique.* In this test a 100-
gram sample of ground, raw refuse was put
inside a bag of Perlon® synthetic fiber cloth,
which is not decomposed by composting. The
mesh of the bag is similar to that of shirt broad-
cloth, preventing loss of the refuse yet allowing
air to move freely through it. Before the bag is
closed, a sealed vial of pure culture of a particu-
lar pathogen is added. The pathogens in the vial
are thus exposed to the same temperature but
not to any microbial interaction of composting,
thereby measuring the pasteurizing effects of
composting. The major part of the test, how-
ever, is inoculation of the 100 grams of refuse
in the bag with free pathogens. A known num-
ber of pathogenic organisms are incorporated
into this bag of refuse, either by injecting them
with a hypodermic needle or by putting them
into a gelatin capsule which melts at the com-
posting temperature. (These careful procedures
are necessary for safety.) These free pathogenic
organisms are exposed both to the composting
temperatures and to the symbiotic or antagon-
istic interaction of all the other microorganisms
within the refuse.
*The complete report of Dr. Strauch's work is pub-
lished as Veterinarhygienische Unersuchugen bei der
Verwertung fester und fliissiger Siedlungsabfalle.
Schriftenreihe aus dem Gebiet des Offenthchen Gesund-
heitswesens, Heft 18, Verlag Georg Thieme, Stuttgart,
Germany, 1964. The work has been summarized in
other German publications and has also been summar-
ized in English as The Importance of Pre-fermentadon
in Composting. H. J. Banse, and D. Strauch. Compost
Science 7(3): 17-22, Autumn-Winter 1966. This work
has also been done relative to human pathogen prob-
lems, and a general survey of it is translated in English
as Public Health and Refuse Disposal. K. H. Knoll.
Compost Science 2(1): 35-40, Spring 1961.
In the study conducted with windrow com-
posting, these small bags were further enclosed
within a larger bag; in a study of drum com-
posting they were protected inside a perforated
steel ball to protect the bag from physical dam-
age. Many bags were removed at various stages
of composting, and the contents were cultured
to determine the die-away rate of the pathogen
and the duration of infection.
It was recognized that the greatest likelihood
of survival would come from sporeforming
pathogens, and possibly from viruses. There-
fore, the pathogenic materials tested by Dr.
Strauch were Bacillus anthrax (anthrax dis-
ease), Salmonella enterides (causes food poison-
ing), Erysipelothrix rhusiopathise (the swine
erysipelas, a skin-lymph disease), and Psittoser-
virus (parrot-fever virus). In corollary work,
typhus and typhoid pathogens have been
tested.* The work was done at the composting
plants at Baden-Baden, Heidelberg, and Bad
Kreuznach, as well as at Frankfurt on an experi-
mental mixture of landfill residue, sewage
sludge, and industrial wastes.
The results show the minimum time-tempera-
ture requirement for killing pathogenic ma-
terial in compost. In windrow composting,
pathogens are killed in 18 to 21 days if the tem-
perature is continuously above 55° C (131° F).
Lower temperatures require a longer time, and
at Frankfurt some pathogens lived after 251
days. The amount of grinding made a differ-
ence: Kills were quicker in shredded refuse.
The frequency of turning was important in
that it assisted in maintaining high tempera-
tures and better contact between pathogen and
substrate.
Pathogenic materials were killed in the Dano
drum (using unground refuse) if held there
for 5 days. Such a long detention time is not
usually practical, and it was found that kill
was equally effective with the normal 3-day
drum dention time plus additional windrow
storage for 4 days. At Heidelberg, where the ref-
use is ground before it is put into die Multi-
*Knoll, K. H. Public health and refuse disposal.
Compost Science 2(1): 35-40, Spring 1961.
26
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FIGURE 50. Screening operation to produce saleable
compost.
Bactor tower, pathogens are killed within 24
hours.
This pathogen appraisal technique has been
well worked out by Dr. Strauch and others at
the University of Giessen. It appears to be
directly usable for similar research in the United
States.
Mineland Reclamation—Bonn. Dr. H. Kick,
professor and head of the Department of Agri-
cultural Biochemistry at the University of Bonn,
has been the leader in research on the use of com-
post in land reclamation. Strip mining methods
are used to remove lignite coal from lands west
of the Rhine River near Bonn. In strip mining
the overburden soil is taken off, and the lignite
is then removed. The first volume of overbur-
den is piled onto undisturbed land. Then, as
the mining progresses across the countryside,
the overburden of the new cut is deposited into
the pit where the lignite was removed. Typical
overburden depths of German lignite mining
vary from 50 feet to well over 300 feet. Since
these lignite fields are "dipped," they grow pro-
gressively deeper, and at some point it becomes
uneconomical to strip off the overburden. At the
end of the operation a substantial pit is often
left, and the whole mine area is lower in eleva-
tion by the thickness of the lignite bed removed.
Although German land reclamation laws re-
quire the mining company to replace topsoil
to the top of the spoil area, a great deal can still
be done—and must be done—to bring such
mined lands back into production.
One particular piece of research work recently
reported by Dr. Kick concerns a plot of land in
the northwestern part of the Rhine River coal
area near Cologne.* The overburden soil above
the soft coal was basically a silt but also con-
tained sand and gravel. Before mining, the
topsoil contained 0.55 percent organic matter
and 35 mg nitrogen per 100 grams soil. After
mining, this same topsoil did have a 1 to 1.5
percent carbon content, but it was recognized to
be primarily waste coal. The pH was 7.3 to 7.5.
This replaced topsoil had lost its structural
characteristics and was susceptible to compac-
tion and slicking over.
Plots of 25 square meters in size (270 square
feet) were treated with various kinds and
amounts of organic and chemical additives and
fertilizers. The basic organic materials were ref-
use compost, dried sewage sludge, and a peat-
moss sewage sludge mixture called "Biohum."
Chemical nitrogen, phosphorus, and potassium
were added as appropriate. The plots were then
planted the first year to mangels (a root-crop
cattle feed), then to cabbage, then to winter
wheat, and finally to alfalfa for 2 years. The
crop yields were all related to the check plot
(no organics and no chemical fertilizers). Yield
in terms of the untreated yield ranged from
97 percent (where the field was overloaded by
applying 125 tons of compost per acre with no
balancing chemical nutrients) to 148 percent
(on plots treated with 60 tons of sewage sludge
plus chemical fertilizer). Nondefinitive ap-
praisals of soil structure were made, and it was
felt that the soils fortified with the organic ma-
terials had better physical properties. This
avenue is being studied further in current
research and, of course, is a key factor in the
reclamation of such lands. An economic ap-
praisal was also made; with present produc-
tion and transport costs the crops were pro-
*Kick, H. Erfahrungen iiber die Kompostverwen-
dung ur Rekultivierung in Bergbaugebieten. Second In-
ternational Congress IRGRD (International Research
Group on Refuse Disposal), Essen, May 1962. (The
Secretariat of IRGRD is at Physikstrasse 5 CH Zurich
7/4, Switzerland.)
27
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FIGURE 51. Top edge of the Bad Kreuznach, Germany,
vineyard soil erosion test plots.
duced more economically with chemical
fertilizers.
Much more work needs to be done on land
reclamation and compost utilization. Professor
Kick is continuing the work in Germany, and
his results will be useful to concurrent Ameri-
can investigation.
Vineyard Soil Erosion Prevention—Bad
Kreuznach. Most of the vineyards that produce
Germany's and Switzerland's fine-quality wines
are on south-facing hillsides whose slopes are
often quite steep (up to 30°). The vines must be
planted on the slope (not on the contour) for
ease in harvesting the grapes and caring for the
plants. Thus, erosion of the exposed soil between
the rows of vines can be a very serious problem.
For as long as farmers have been growing grapes
on these hillsides, they have used organic matter
to help hold the soil in place. The usual ma-
terials have been animal manures, straw, and
other crop residues. With the expansion of vine-
yard acreage and the increased mechanization
and specialization of agriculture, it has become
more difficult and more costly to obtain these
usual organic materials. Compost made from
municipal refuse is a good substitute and has
been used in rather substantial amounts. In fact,
it is estimated that 60 percent of Germany's com-
post production is used in this manner, and
compost probably accounts for 5 to 10 percent of
the organic matter used in those vineyards.
Research on the use of compost in wine vine-
FIGURE 52. View down the slope.
yards has been conducted at a number of places
in Switzerland and Germany. Probably the most
comprehensive has been (and still continues) at
Bad Kreuznach, Germany. The present re-
searcher is Dr. I. Bosse, a research scientist em-
ployed by the state (Rhine-Hessian); previously,
the researcher was Dr. H. J. Banse. The research
has been conducted for 9 years.
The early research efforts were concerned
with making compost: satisfactorily and eco-
nomically. In the early years Dr. Banse worked
closely with the plant operation and with the
Dano Co. in proving out the drum composting
system. Later, Dr. Banse cooperated with Dr.
Strauch from Giessen in the pathogen survival
studies covered earlier in this report.
Recent work, begun by Dr. Banse and being
continued by Dr. Bosse, relates to use of the
compost. Some of this work has related to the
nutrient content of compost and the nutrient
availability of organically enriched soils. This is
a long-term study, and definitive results are
not yet available.*
An especially important and conclusive com-
post utilization experiment at Bad Kreuznach
is concerned with soil erosion. This experiment
is presently in its seventh year. Figures 51 and
52 are photographs of the 30.1° slope on which
catch basins are installed. Each plot is 20 square
*I. Bosse. Humusersatz in den Weinbergen. Feld
und Wald 23, June 4, 1965.
28
-------
meters (215 square feet) on the horizontal pro-
jection; this is 23.1 square meters (248 square
feet) of surface exposure. The plots are growing
typical grapes farmed in the typical way except
for the compost application. Compost is applied
every third year at the rate of 89 metric tons per
hectare (79 tons per acre); 178 metric tons per
hectare (158 tons per acre); and no compost
(the check plots).
The surface is covered about one-half inch
deep by the 79 tons of compost, and about 1
inch deep by the 158 tons of compost. The com-
post is mulched into the top surface a bit, but
not incorporated thoroughly.
Figure 53 shows the average yearly runoff
water loss, and soil loss carried by the runoff
water.
The compost acts to reduce soil erosion in
three ways: The crumblike resilient compost
material on the soil surface absorbs some of the
energy of the falling raindrops, thereby pro-
tecting the more sensitive soil particles; the
compost inherently has a high water-holding
capacity—like a sponge—thereby retaining
water better within the soil-compost material
and reducing runoff; as the compost is biolog-
ically converted to soil humus, it promotes ag-
gregation and textural strength of the soil
particles so that they resist erosion better.
This very positive benefit from using compost
on hillside vineyards is the basis of compost use
by the grapegrowers of Germany and Switzer-
land. Compost may or may not have secondary
benefits, but reduction of soil erosion is sufficient
economic justification to the grape farmers
today.
On a nearby test plot Drs. Banse and Bosse
have run studies on the increased moisture-
holding capacity of compost-fortified soils.
Those results are shown in Figure 54. Although
the slopes are less steep (about 8°) than in the
other study, water not absorbed into the soil
during a rain does run off. Thus, the compost-
treated plots have more water available for
plant growth. Research is being continued to
determine whether this results in greater yields
or better quality of grapes and wine.
Compost Utilization in Basic Agriculture—
Braunschweig. In all uses of compost today, the
No Compost
79 Tons Compost/Acre |
J159 Tons Compost/Acre
1000 2000 3000 4000 5000
GALLONS OF RUNOFF/ACRE-YEAR
No Compost
79 Tons Compost/Acre |
159 Tons Compost/Acre
50 100 150
CUBIC FT OF SOIL LOSS/ACRE - YR.
FIGURE 53. Average water and soil loss from 30.1°
vineyard slopes at Bad Kreuznach, Germany.
important factor is the organic matter in the
compost, not the nutrient content. Before chem-
ical fertilizers became generally available, nutri-
ent content was important in manures, com-
posts, and other organic materials used by
farmers. But, as indicated earlier, the nutrient
content is very low (typically 0.5 percent nitro-
gen, 0.4 percent phosphorus, and 0.2 percent
potassium). At today's prices of 8 to 10 cents
per pound for chemical nitrogen, 15 to 16 cents
for phosphorus, and 6 to 7 cents for potassium, it
can be seen that 1 ton of compost has rather
negligible nutrient value. When chemical fer-
tilizers first became generally available, soil re-
search compared chemicals with organics, and
the latter almost invariably came out second
best. Today, the research has taken on more
sophistication. Research is being conducted on
organics plus chemicals, the intention being to
obtain maximum yield along with maintenance
and improvement of the land.
The "Forschungsanstalt fur Landwirtschaft"
(Research Station for Agriculture) of the Fed-
29
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30
_ 78 TONS COMPOST/ACRE
' x>v r—\
/x V \
Z 20
111
O
£
U 10
LOAM SOIL
'
3 - 78 TONS COMPOST/ACRE,
CLAYLOAM SOIL
A
3 6 9 12 3 6 9 12
I960 1961
FIGURE 54. Soil moisture regime on two vineyard soils at Bad Kreuznach, Germany.
eral Republic of Germany, at Braunschweig-
Volkenrode, is somewhat equivalent to the
U.S. Department of Agriculture's Beltsville,
Md., Experiment Station. In World War II the
former was a secret research station for the Ger-
man Luftwaffe. Most of the land then was in a
60-to-lOO-year-old mixed forest, making it pos-
sible to hide an elaborate research complex.
After the war nearly half the forest was cut
down for timber and firewood. (This is in con-
trast to the usual German practice of selective
harvesting.) The adaptability of the buildings
for further research, plus the clearing of virgin
land, was the basis for founding the Agricultural
Research Station at this location.
One of the 12 research groups at the Research
Station is the Institute for Humus Management.
Research at that Institute is aimed at maintain-
ing and improving both crop yield and soil qual-
ity through husbanding the soil organic matter.
Much of the research of this Institute has dealt
with compost utilization. In recent years this
has been conducted by Dr. C. Tietjen. One of
his important research contributions deserves
summary here.
Composts or manures added to the soil
undergo biological stabilization. Byproducts of
this microbial activity include humic acids and
humus materials. These latter are quite effective
in improving the physical characteristics of soils,
through improving the soil's structural "fabric."
One can ask whether the applied organic matter
should be well rotted or should be relatively
fresh. The argument for using well rotted
materials is that one incorporates a material
much like humus itself and so the soil microlife
is minimally disturbed—thus crop yields are not
so likely to be depressed in the year of applica-
tion. The argument for applying fresh material
is that the farmer supplies more microbial
"food," effecting a greater degree of soil
improvement.
One of Dr. Tietjen's long-term compost
utilization studies is concerned with this par-
ticular question. Compost directly from the Bad
Kreunzach drum (5 days of rotation) is being
compared with compost that has "cured" for 9
months after being removed from the drum.
(The field plots are on healthlike sandy soil at
Braunschweig; the compost is shipped from
Bad Kreuznach.) Table 2 lists the composition
of the composts used in the study.
TABLE 2. COMPOSITION OF COMPOST USED IN THE
BRAUNSCHWEIG STUDY ON AGE OF COMPOST
[In percent]
Fresh Cured
compost compost
Organic content
Nitrogen
Phosphorus (as PjOs) . .
Potassium (as K^O)
Calcium (as CaO)
Magnesium (as MgO). . . .
28 4
.48
29
.41
2.91
.90
19.1
.46
.31
.45
3.78
1.05
30
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TABLE 3. EFFECT OF FRESH AND CURED COMPOST ON YIELDS*
Year of application 2d year (rye)
(potatoes)
3d year (oats)
Fresh
Cured
Fresh
Cured
Fresh
Cured
No nitrogen:
+no P2O5
-f- adequate P2Ofi
Medium nitrogen:
+noP205
+ ad equate P2OS
High nitrogen:
+no P2O5. . .
+ adequate P2OS
97
98
95
95
93
99
117
117
104
99
103
100
134
145
118
127
112
112
117
128
111
121
107
108
122
131
113
118
111
114
111
123
111
113
108
107
*Yields in each treatment are expressed as percent relative to equivalently fertilized [with chemical
fertilizer] but noncomposted plots
These two composts were applied to the indi-
vidual plots at 100 metric tons per hectare (89
tons per acre) at the beginning of the experi-
ment. At the end of the first 3-year rotation,
compost was applied again—at 90 metric tons
per hectare (80 tons per acre)—and a like 80
tons per acre was applied again between the
second and third 3-year rotations. Chemical fer-
tilizers were applied each year: sufficient potas-
sium to all plots; sufficient phosphorus to half of
each plot and none to the other half; and nitro-
gen at three rates—zero, medium, and high.
(The effect of nitrogen is twofold: It serves as a
nutrient to the plant being grown; and it fer-
tilizes the soil microorganisms attacking the
added compost.) The crop rotation was pota-
toes, rye, and oats. The soil was a silty sand
with a pH of 5.8. Figure 55 is a photograph of
the plots at the ninth year harvest (of oats).
Table 3 presents the averaged yield ratios
(combining potato yields of years 1, 4, and 7;
rye yields of years 2, 5, and 8; and oat yields of
years 3, 6, and 9.) The fresh compost depressed
the yield of the first crop (potatoes), whereas
the cured compost effected a slight yield in-
crease. Yields in the second and third year were
higher for both kinds of compost than for
equivalently fertilized but noncomposted plots,
with fresh compost superior to cured compost
in yields produced. By taking the average of the
averages, one can say that cured compost in-
creased the yield relative to equivalently chemi-
cally fertilized but noncomposted plots by 11.1
percent, and fresh compost increased the yield
by 11.7 percent. However, the plots well ferti-
lized with chemicals but without compost out-
produced poorly fertilized but composted plots.
Thus, the farmer will generally prefer to buy
and spread more chemical fertilizer rather than
buy compost.
The nutrient levels of the harvested crops
were measured each year, and the data are
averaged in table 4. In the first year, cured com-
post was superior to the fresh compost in in-
creasing the nutrient content of the crop, but
in the second and third years the fresh compost
was definitely superior.
FIGURE 55. Dr. C. Tietjen's compost utilization experi-
ment at harvest time.
31
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TABLE 4. EFFECT OF FRESH AND CURED COMPOST ON NUTRIENT LEVELS OF CROPS*
Nutrient in harvested crop
Year of application 2d year (rye)
(potatoes)
3d year (oats)
Fresh Cured Fresh Cured Fresh Cured
Nitrogen
Phosphorus (PgOg) ....
Potassium (K2O)
101
101
104
121
103
111
128
138
127
119
120
116
132
129
135
113
119
117
*Yields are percentages relative to noncomposted but otherwise equivalently fertilized plots.
Responses of the soil to the compost applica-
tion and crop rotation were measured in the
seventh and eighth years, and the data are aver-
aged and presented in table 5. As can be seen,
compost additions increased the soil organic
content and pH. This improved the physical
structure of the soil and may well account for
the better yields of composted plots than of
equivalently chemically fertilized but noncom-
posted plots.
TABLE 5. SOIL CHARACTERISTICS IN THE COMPOST RIPE-
NESS EXPERIMENT
Organic carbon (mg/lOOg).
Total nitrogen (mg/lOOg) . .
Available P2O5 (mg/100g). .
Available K2O (mg/100g). .
Available Mg (mg/lOOg) . .
pH
r
No
com-
post
1950
124
21
17
8
5.9
Fresh
com-
post
2300
153
31
30
13
6.8
Cured
com-
post
2280
145
31
29
14
6.5
In this experiment, as in others that Dr.
Tietjen has conducted, it is obvious that com-
post does help the soil itself and does improve
yields over those of equivalently fertilized (with
chemicals) but noncomposted plots. The real
limitation is that high applications of chemical
fertilizers alone give a higher crop yield than
medium levels of chemicals plus compost. Thus,
the farmer is tempted to spend his available soil-
improvement money exclusively on chemical
fertilizers rather than dividing it between com-
post and chemical fertilizers.
Dr. Tietjen is trying to measure the long-term
effects of cropping with and without composts
and other organic matter. The argument can
be advanced that although chemical fertilizers
may be more profitable for the short-term, soil
organic maintenance through compost addi-
tions may be in order for the long term (50-
100-200 years into the future). This research
work is not yet in excerptable form, and there-
fore cannot be reported here.
Dr. Tietjen has summaried the present situa-
tion well. Reporting at the 1963 National
Conference on Solid Waste Research,* he made
the following pertinent summary:
Viticulture, fruit-culture, and horticulture are spe-
cial branches of land use, with special fertilization and
cultivation requirements. They generally do not have
sources of organic matter as a part of the enterprise. It
is different in basic agriculture—in the production of
small grains, corn, potatoes, sugar beets, and other
crops. In most cases here a supply of organic matter
can be found on the farm, such as stable manure on
mixed farms, crop residues, green manures, and most
important, a crop rotation that benefits the soil. Where
specialty farmers are under economic pressure to pro-
duce crops without the possibility of providing for their
own humus husbandry, refuse compost can be con-
sidered an available substitute resource.
*Tietjen, C. Conservation and field testing of com-
post. Utilization of composts in Europe. In Proceedings,
National Conference of Solid Waste Research, Dec.
1963. Special Report No. 29. Chicago, American Public
Works Association, p. 175-186.
32
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The Potential for Composting and Compost Utilisation
in the United States
The preceding sections have attempted to put
composting and compost utilization into per-
spective. It appears to the author that there are no
real technological barriers to making compost.
It does appear, however, that the utilization of
compost is limited. There are successes in luxury
agriculture, as evidenced in vineyard, flower,
and landscaping uses, but basic agriculture can-
not be expected to absorb the material. Further,
the concept of composting must be considered
from the municipality's viewpoint. Most mu-
nicipal officials recognize that it is not possible
to make money from refuse. The most that can
be expected, with regard to composting, is that
the net cost to the city for refuse disposal by
composting will be less, or no greater, than the
costs of disposing of the garbage by landfilling
or incineration, or a compensating value can
be put on the factors of reduced rate of con-
sumption of burial sites or reduced air pollution
relative to incineration.
It does appear that in the United States there
are three specific areas in which refuse processing
and discharge through composting have poten-
tial: (1) Small amounts of compost can be
marketed for luxury agriculture, in which case
the overall economics—to the producing mu-
nicipality and to the user—are favorable. (2)
The finished compost has value, but the eco-
nomics—for the producer or for the user—must
be related to intangible values. (3) The finished
compost is either not valuable or only mar-
ginally so, but the overall economics are
nonetheless favorable.
Condition 1: Compost for Luxury Agricul-
ture. The concept of using compost in luxury
agriculture has been adequately discussed in
preceding portions of this report. The success in
Holland is due to an emphasis in specialty and
luxury crop agriculture, and an aggressive and
dynamic sales organization. The United States,
with its high standard of living, also supports
a significant specialty agriculture. No truly
dynamic and efficient marketing organization
for compost, however, is yet in existence. If it
were, some small percentage of this nation's
domestic refuse could probably be utilized at an
economic advantage to both producer and user.
The percentage so handled would unquestion-
ably be less than Holland's 17 percent but could
certainly be as great as Germany's 0.5 of 1 per-
cent. Possibly 1 percent is a realistic figure; this
would amount to beneficial, economic conver-
sion of the wastes from 2 million people.
Locations where composting operations could
be successful would have to be selected with ex-
treme care. A market analysis would have to
be the first step; transport costs are so great that
the compost must be marketable in the local
area. Three examples of this market sensitivity
are pertinent. For a number of years the Met-
ropolitan Waste Conversion Corp. at Largo,
Fla., was successful in making and selling a
limited amount of domestic compost. In 1966
33
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St. Petersburg, only 15 miles from Largo, in-
stalled a 105-ton-per-day refuse conversion plant
which was able to make 50 to 60 tons of compost
per day. This quantity completely saturated the
market, so that Metropolitan Waste Conversion
has ceased operations at Largo. And St. Peters-
burg has yet to solve its marketing problem.
In 1965 to 1966, Houston, Tex., let contracts
for two composting plants. It seems likely that
there will be serious marketing problems when
and if both plants get into full operation.
One might think Los Angeles would be a
good area for composting because of all the gar-
dening and outdoor living. But refuse compost
must compete there with dried and composted
dairy manure—higher in nutrients and with
other quality characteristics as good or better.
And the manure sells for one-half to two-thirds
cent per pound in bags at retail garden stores
and supermarkets; compost from domestic ref-
use just cannot compete.
There may well be other markets, as yet un-
tapped, for compost. With further processing,
compost could be pelletized to serve as an or-
ganic carrier for chemical fertilizer. In Holland
some compost is sold as a litter material for live-
stock housing and as a mulch for packing bulbs.
There are antibiotics and vitamins in compost
that might be recovered. But even with these
markets it appears that the quantity of corn-
post that could be beneficially utilized is small—
the 1 percent suggested earlier.
Condition 2: Compost Has Value and Eco-
nomics Do Not Control. After the above empha-
sis on a proper economic approach, one might
question the idea of compost production and
utilization under a less-than-favorable economic
situation. But man neither lives by bread alone
nor thinks in tangibles alone. The intangible
of enviromental management, if not environ-
mental improvement, can and should be a
powerful force. Compost production and utiliza-
tion might be justified on the basis of lesser
insult to the environment. Compost production
and utilization might be justified on the basis of
improvement of our already despoiled resources.
Hypothetical but specific examples of the po-
tential of composting in this area are numerous.
A city might be investigating incineration and
composting. The net cost of composting might
be greater than that of incineration, but climatic
or geographic factors might be such that the
extra air pollution from incineration would be
undesirable. Composting might thus be a better
choice, and the additional cost of composting
would be recognized, acknowledged, and paid.
The noneconomic benefit of composting
within the city's wastes management program
can be cooperative rather than competitive. It is
generally acknowledged that landfilling is the
least expensive waste disposal method. In fact.
landfilling is always a necessary part of a waste
disposal program. Incinerator ash must be
buried. The uncompostable plastics, glass, and
other material must be buried. The city's build-
ing and demolition wastes must also be buried.
Yet even sanitary landfilling has disadvantages—
excessive land use and possible water pollution
problems. Landfilling can not be abandoned
because it may have these faults. Rather, the
landfilling practice should be improved to
eliminate such faults. Composting can assist
in this. Diversion of compost to other uses, of
course, reduces the volume of material going
into the fill. And even if refuse is made into
rough compost and the compost put into the
landfill (not sold), there is a volume reduction.
Further, filling a landfill with uncompostable
residues—or the compost itself—would be more
sanitary and less likely to cause water pollution
than landfilling with raw refuse.
There is a second way in which composting
can aid the landfilling operation. Sanitary land-
fills are usually used until they fill a depression
or until they run out of cover dirt. Yet an above-
grade sanitary landfill to build a hill or moun-
tain is very desirable for future recreational use.
One can visualize a percentage of a city's gar-
bage being composted to produce cover ma-
terial for burying the rest of the refuse. In this
way a rubbish mountain, covered with trees and
grass growing on compost, would benefit future
inhabitants of the city.
There is a very important area where compost
utilization can be beneficial although the eco-
nomics are not favorable on a basis of immediate
34
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or tangible returns. This area is the reclamation
of despoiled lands. Strip mining for coal, iron,
gold, and other resources, has already defaced
800,000 acres of land in the United States. It
was not economic during the mining, and it is
not economic today, to repair these disfigura-
tions of our landscape. Yet we are embarked
upon a program of national beautification, and
as a matter of policy we intend to reclaim these
blighted spots. Organic matter is definitely
needed on some of the mine-spoil and debris
piles, and compost from municipal waste is a
logical source of this organic matter. Some re-
search is planned at the Joint U.S. Public Health
Service-Tennessee Valley Authority Compost-
ing Project, Johnson City, Tenn., to study
reclamation of sites blighted by strip mines.
Worthwhile in this endeavor will be some of the
research at Blaubeuren, Germany, and Dr.
Kick's work at the University of Bonn,
Germany.
In the future, as recreational areas for the ex-
panding population become more valuable, it
may become feasible to reclaim naturally bar-
ren or infertile areas. Organic matter is a first
need of such lands, and, again, compost is an
appropriate material. A specific example of a
possible area of use is in the reforestation of
wastelands of shallow soil that are marginally
watered. Trees will often grow on north slopes,
where drying out of the soil is less severe, while
south slopes are dry and barren. As shown
earlier, compost improves the soil's water-hold-
ing capacity. It might well be that compost in-
corporation, along with forest management,
could reclaim these south slopes.
All of these ideas are desirable and beneficial,
but hardly economic. At least, it is hard to
justify their worth through straightforward eco-
nomic analysis. The intangible of future beauty
does not have a generally agreed upon present
dollar value. However, in the coming years
some of this land reclamation and beautification
will occur and will be able to utilize compost.
In honesty, probably less than 1 or 2 percent of
the nation's refuse generation would be chan-
neled into this disposal—but it would certainly
be a desirable avenue.
Condition 3: Compost—Nonbeneficicd but
Economic. There is a third and last concept
under which composting and compost utiliza-
tion can proceed, and this has greater potential
than either of the choices discussed above. It is
a middle ground, between using compost at 15
to 50 tons per acre-year for crop production or
land improvement, and using the land as a
refuse burial site. (About 800 tons of refuse will
raise the elevation of 1 acre of landfill site by 1
foot.) Conceive of the application of 100,200, or
300 tons of rough-quality compost per acre per
year, year after year. The land would be an ac-
ceptor, degrader, and stabilizer of the waste;
crop production would probably not occur; but
neither would the land be lost to a future use.
The concept is similar to that involving the
use of land for sewage irrigation. A community
decides it cannot afford a sophisticated sewage
treatment plant, and so it makes a parcel of land
into a sewage spreading ground. The land and
the sewage are not used for crop production, but
only to get rid of the sewage. Hopefully, after
a few years the community will build a sewage
treatment plant, and then the land can again
be used for agriculture, or for subdivision, or
recreation, or something else.
This philosophy and system is equally appro-
priate for solid waste management. Put bluntly,
it would be insulting Mother Earth without
quite violating her. Each year, as much rough
compost—or perhaps just ground refuse—
would be incorporated into the soil as could be
assimilated. When the land is needed for an-
other purpose, the compost application would
be stopped, and the land would recover. This
concept of compost utilization might be likened
to a biological incinerator. The applied organic
matter would be burned and consumed by the
soil microbiological activity. The operating cost
of this biological incinerator will probably be
higher than running a thermal one, but the
capital cost, and thus the amortized cost, should
be much lower. For many cities this scheme
might well be preferred over conventional in-
cineration. As a hypothetical example, if a soil
could take 100 tons of rough compost per acre
per year, produced from 200 tons of domestic
35
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refuse, this would be a land requirement of 1
acre per 500 people. This is even less land than
is required for sewage lagoons.
One of the beauties of the system is its possible
political expediency. A rose by any other name
is still a rose, and possibly garbage burial as sug-
gested here is still garbage burial, but if it is
called and considered "organic dressing of the
topsoil," it might be accepted by a community
that adamantly opposes the conventional
sanitary landfill.
Needed research on the soil science, the engi-
neering practicability, and the economic feasi-
bility have not yet been worked out, but is
beginning (at the University of California
under USPHS Research Grant SW 00003). The
research teams are trying to determine the
maximum assimilative capacity of soil for or-
ganic matter, and whether the form is im-
portant—as raw ground refuse, as fresh com-
post, or as cured compost. The best way to apply
the waste must be determined—as a top dressing,
mixed into the top few inches of soil, or thor-
oughly incorporated into the soil. The econom-
ics of tillage, pH control, frequency of applica-
tion, and similar variables must all be worked
out.
At this stage it is impossible to estimate what
percentage of the nation's refuse might be so
managed. It would appear that this system
might have merit for communities with popula-
tions between 10,000 and 100,000. There are 1,760
such communities in the United States, with a
total population of nearly 50 million, or 25 per-
cent of the nation's population. If this method
of refuse disposal were appropriate for even one-
third of these communities, it would be a
substantial avenue of waste disposal.
36
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Recommendations for U.S. Composting Research
With the passage, in 1965, of the Solid Waste
Disposal Act by the Congress and the President,
this nation is embarked upon a comprehensive
solid waste management program. One part of
that program is support for research and de-
velopment—to find answers today for tomor-
row's problems. This research in solid wastes
embraces all areas of management—collection,
storage, transport, processing, and discharge. A
goodly part of the research presently sponsored
by the U.S. Department of Health, Education,
and Welfare involves aspects of composting.
Even so, there appears to be room for additional
research effort in the composting field. Such
additional research would complement the pres-
ently supported research.
Marketing Research. The need for a market
analysis prior to construction of any new com-
posting plant was suggested in the preceding
section. But also much in order is a more com-
prehensive marketing research study for the
general proposition of composting. It should be
determined what the total extent of the market
for compost is, what qualities of compost make
for salability, what the going price could be, and
what the competition would be (from manures,
peat moss, and sewage sludge). Such a market
survey could determine whether compost really
has a future for luxury and specialized agri-
culture, or whether composting advocates just
do not have the facts straight.
This survey might be expanded to cover com-
post use possibilities suggested in the second
part of the preceding section—compost for land
reclamation. Transport costs, compost quality
requirements, and sources of financing for the
use of the compost would all be a part of such a
study. It might even be possible to investigate
whether advertising and a "Madison Avenue
Approach" could appropriately be applied to a
Compost Utilization program.
It seems unlikely that academic researchers
would be interested in—or capable of—con-
ducting this type of market survey. Rather, such
a study might best be contracted out either to
strictly commercial companies or to nonprofit
research organizations.
Composting Cost Studies. Related to the mar-
keting of compost is the cost of preparing the
compost for market. Composting was first con-
ceived of as benefiting basic agriculture, and
compost of rough or poor quality was deemed
adequate. Over the years this market has been
unsatisfactory, so quality has been continually
upgraded by extra sieving, crushing, grinding,
ballistic separation, incorporation of fillers and
chemicals, pelletizing, and the like. Much re-
search on the biological processes of composting
is already being supported. But it is the me-
chanical processes and the simple materials-
handling problems that, more than anything
else, contribute to the cost of composting. It
seems appropriate that a cost-engineering ap-
praisal be made of the mechanics of composting.
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What is the comparative cost of grinding refuse
before versus grinding after composting? What
is the cost of sieving compared to ballistic sepa-
ration? These and other cost-comparatives
studies should lead to a more economical com-
post manufacturing process, and to a compost
tailored to specific markets. This could be grant-
supported research if some university acade-
mician were interested, or it could be contract
research. This information, plus the marketing
research, would do a great deal toward put-
ting composting into place and into proper
perspective.
Wasteland Reclamation Research. It was pre-
viously stated that minelands and other waste-
lands can be an acceptor of compost. Research
by Drs. Kick and Spohn in Germany was dis-
cussed, and the intent of the PHS and TVA
personnel at the Johnson City composting plant
to engage in this was mentioned. This is ex-
tremely important work, and should be pursued
diligently and energetically along two lines—the
technology of land reclamation, and the en-
gineering economics. It would be very desirable
if a team of a soil scientist, an agricultural en-
gineer, and an economist could become active
on this project. The soil scientist could design
and test the various experiments and programs
of strip mine reclamation in the Appalachian
area near Johnson City. The agricultural en-
gineer could assist in the application equipment
design and procedure, and the economist could
interpret the financial conditions. Within 10
years there could be developed a real backlog
of knowledge and understanding of the prob-
lem, and of methods of solution.
This work could be done by academicians
from nearby universities (University of Tennes-
see and University of Kentucky) working with
the PHS and TVA personnel at Johnson City.
If the academicians are not particularly in-
terested, however, the work should be pursued
directly with government research scientists.
Pesticide Degradation in Organically En-
riched Soils. Ever since Rachel Carson wrote the
book Silent Spring, the problem of pesticide resi-
dues has been generally acknowledged. It has
been indicated by some initial research (by Dr.
Strauch and Dr. Farkasdi at the University of
Giesson, Germany) that pesticide residues are
degraded more quickly and more completely in
compost-enriched soils than in normal soils. This
is a most significant hypothesis, and one worthy
of immediate and dedicated research. If it is
true, it could be an important reason for using
compost in basic agriculture. And, more im-
portantly, it would assist in reducing the pollu-
tion of our environment from the pesticides
being used in ever-increasing amounts.
This appears to be research that could well be
conducted at universities with USPHS research
grant monies. It would require a team ap-
proach—of soil microbiologists and agricultural
toxicologists or chemists. This research should
be fundamentals oriented, aimed at learning
the process and metabolism of pesticide break-
down. Application of the findings would be a
second step, dependent upon the basic research
developed by the fundamentals study.
Pathogen Survival Research. As previously re-
ported, Dr. Strauch at: the University of Giessen,
Germany, ran comprehensive studies on patho-
gen survival during the composting process.
This is so important to the future of compost-
ing in the United States that supplementary
work might well be conducted here. This could
probably best be pursued at the Joint U.S. Pub-
lic Health Service-Tennessee Valley Authority
Composting Project, Johnson City, Tenn. It
would also be extremely desirable if Dr. Strauch
could be hired for a year to consult with U.S.
scientists in this study.
Also worthy of research effort is a second as-
pect of microorganism activity in compost. The
composting process is a biological degradations
fungi and bacteria attack and degrade the raw
waste and convert it into compost. As the com-
posting is completed, many of these microorga-
nisms sporulate so as to await a more optimum
food supply later. The compost is used on the
land, perhaps on some specialty food crops. Does
the food become contaminated with the com-
post-processing microorganisms ? Does canning,
pickling, or the other food-processing operations
kill the spores? Or could these spores become
active again and cause food spoilage and food
poisoning problems? Research on compost
38
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utilization and food spoilage is thus an appro-
priate area of academic research. It could well
be supported by U.S. Department of Health,
Education, and Welfare grant monies.
The Land as an Acceptor of Wastes. Really,
nothing more needs to be said here about this
research proposal, since it has been discussed in
the preceding section (p. 33 to 36). This does
seem to be the greatest potential for compost or
raw refuse discharge in the future. Research on it
is already beginning at the University of Cali-
fornia, under USPHS Project SW-00003.
Conclusions
Composting has frequently been advocated
and considered as a method of solid waste man-
agement in the United States. The key to success
or failure of American composting has been and
will continue to be related to whether and how
the finished compost can be utilized or dis-
charged.
Today substantial quantities of compost are
being produced and utilized in Europe. A study
and analysis of compost utilization there should
be helpful in appraising the potential for success
of future American composting operations. To
this end, a study of compost utilization and
compost utilization research in Germany,
Switzerland, and Holland was undertaken in
1966 and 1967.
The results of that study, including visits to 14
composting plants and various research organi-
zations, led to the following conclusions:
1. Compost in Europe primarily has useful-
ness in intensive, luxury-type agriculture. It is
used in flower and fresh vegetable culture where
frequent tillage tends to destroy soil fabric, and
on hillside vineyards where erosion control is
necessary.
2. Compost plus chemical fertilizers can be
used in general agriculture (cereal and field
crops) but maximum yields at minimum cost
are obtained with chemical fertilizers alone, and
soil tilth is adequately maintained with normal
crop rotations.
3. Reclamation of strip mined areas with
compost is being actively researched and offers
considerable promise.
4. Public health considerations regarding
compost production have been well researched
by scientists at the University of Giessen,
Germany.
5. Compost utilization in the United States
appears to have limited potential, and such
utilization is likely along three routes:
a. Commerical, economic utilization of com-
post in the conventional manner—for intensive,
luxury-type agriculture. Perhaps 1 percent of
the nations' domestic refuse might be utilized
in such a manner.
b. Utilization of low-grade, economically
produced compost for land reclamation and
cover material for sanitary landfills. Perhaps 1
to 2 percent of the nation's domestic refuse
might eventually be so channeled.
c. Compost (or ground refuse) spreading
and incorporation onto certain lands, using the
land plus the composting process to stabilize
organic wastes, rather than using compost to
benefit the land. Composting would be a type
of biological incineration with the land being
the incinerator. Such a scheme could be sanitary,
feasible, and perhaps economic for small towns
and cities (to perhaps 100,000 in population).
Perhaps 5 to 8 percent of the nation's domestic
refuse might eventually be so managed.
6. Although considerable U.S. Public Health
39
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Service-sponsored research on composting is
already in progress, additional studies are appro-
priate in the areas of compost marketing, com-
posting unit operations costs, wastelands
reclamation, pesticides breakdown in or-
ganically rich (compost-fortified) soils, patho-
genicity in the actual utilization of compost,
and land as an acceptor of wastes.
40
U.S. GOVERNMENT PRINTING OFFICE: 1E68 O- 309-787
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U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Public Health Service Publication 7\[o. 1826
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