TENHUNEN@finujo.bitnet (04/03/89)
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*HEAT RECOVERY COMPOSTING PLANT IN AN INTEGRATED PRODUCTION*
*OF COMPOST, EARTHWORMS, FISH BREED, GREENHOUSE, AND OUTDOOR*
*CULTURES: a demonstration project of VJ-Komposteringssystem*
*AJ, sponsored by EC. Part I: The composting processes *
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1
INTRODUCTION
============
This project has the aim to achieve maximum utilization of
the organic waste projects which are a potential energy
source and raw material for compost products. The compost
products are tested for greenhouse and outdoor use before it
is sold as a declared compost. Also, the aim is to demonst-
rate less-pollution problems with agricultural and other or-
ganic wastes.
The plant is built in the Danish parish of Aulum-Haderup in
an area of 10 hectares in the vicinity of the factory of
Praeriemuld A/S. Many fur and poultry producers, with a
large surplus of animal manure, are located in the area, and
they are very interested in the delivery of manure to the
plant.
Most of the income will be brought by an eel breeding plant.
The wastewater produced by this plant will be treated in the
water-hyacinth greenhouses. The sludge will be treated with
the separated slurry in an anaerobic filter. Part of the
effluent from the filter will be totally treated by the
water-hyacinths, and the other part will be used for land
application.
2
DESCRIPTION OF THE SOLID MATERIAL LINE
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2.1
Receipt of the organic substrates
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At the plant, the different substrates (poultry and fur ma-
nure, straw, chips, bark, and peat, or the like), will be
received and stored separately under a cover.
2.2
Substrate mixtures
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The substrates will be analyzed in a laboratory for relevant
physical and chemical properties, and the desired mixtures
will be formulated by means of a computer. The plant will
be scaled for the treatment of ca. 2.630 tons of organic
substrate per year, corresponding to ca. 7,2 tons (ca. 10
cubic meters) per day.
2.3
Composting heat plant (CH plant)
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The substrate mixtures will be composted for 5 - 7 days in a
composting heat plant. The main characteristics of the
plant are as follows:
1) The composting process will be fully controlled with a
subsequent high rate of composting. In 5 days, ca. 30 per-
cent of the substrate solids will be converted into carbon
dioxide and water.
2) The plant will be a closed system, where the whole bio-
mass will be exposed to a temperature of 60 degrees Centi-
grade for 5 days, so that the substrate will be sanitized
for pathogens, parasites, and weed seeds.
3) Ca. 70 percent of the biologically produced heat energy
can be exploited by the heat exchanger system, while the
rest will be lost with the exhausted air.
4) The exhausted air will have an increased content of
carbon dioxide, and after a purification this air can be
utilized for the heating and carbon dioxide enrichment of
the greenhouse atmosphere.
5) Nitrogen loss during the process will be limited due to
process adjustment and the collection of evaporated ammonia
to the water of the air scrubber in connection to the heat
exchanger system.
In this project, the heat produced by the CH plant will be
used for the heating of the greenhouse, eel culture, vermi-
culture, and for the heating of the connected building con-
taining laboratory, packing equipment, administration, etc.
The carbon dioxide formed will be utilized for the promotion
of plant growth in the greenhouse, while the ammonia-en-
riched water will be utilized as as a liquid fertilizer for
outdoor vegetables.
When the CH plant will receive ca 7.2 tons of substrate per
day, corresponding to ca. 10 cubic meters per day, and the
plant will have the treatment time of 5 days, a plant volume
of 50 cubic meters will be necessary.
The plant will produce ca. 3.7 tons of fresh compost per
day (1,350 tons per year), and the power will be 50 kW (ca.
38 tons of oil equivalent per year). Energy consumption of
the plant for the structuring and aeration of the material
will be 6.5 kW (ca. 5 tons of oil equivalent per year).
2.4
Curing
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The fresh (raw) compost coming from the CH plant don't be
sufficiently stabilized (mature) for use as a growth medium
for plants, and it can cause damage to the plants or rest-
raint of germination. This compost must therefore be cured,
partly by windrow composting and partly by vermicomposting.
2.41
Windrow composting
One-third of the fresh compost (450 tons per year) will be
stabilized in windrows. The stabilization process will take
place indoors in 4 - 8 weeks, depending on the wanted matu-
rity index wanted for the compost. In this period the com-
post will be turned, structured, aerated and moistened se-
veral times by means of a turning machine. Fresh and cured
compost will be removed by means of a front-end loader. The
production of cured compost will be ca. 210 tons per year.
2.42
Vermicomposting
Two-thirds of the fresh compost (ca. 900 tons/year) will be
stabilized by means of vermiculture, which will take place
in an insulated hall at 25 degrees Centigrade in a system of
trays in 7 storeys.
In the vermicomposting process, a tropical species from East
Asia, Perionyx escavatus, will be used instead of the spe-
cies Eisenia foetida (manure or dung worm), which is common
in Denmark, and until now the species mostly used for vermi-
culture. The two species are more or less equal according
to the size, growth, and reproduction potential, but Peri-
onyx excavatus doesn't - as in the case of Eisenia foetida -
segregate any evil smelling secretion, which means that it
can be utilized directly as a living fodder in fish produc-
tion.
(To be continued)TENHUNEN@finujo.bitnet (04/10/89)
*************************************************************
*HEAT RECOVERY COMPOSTING PLANT IN AN INTEGRATED PRODUCTION*
*OF COMPOST, EARTHWORMS, FISH BREED, GREENHOUSE, AND OUTDOOR*
*CULTURES: a demonstration project of VJ-Komposteringssystem*
*AJ, sponsored by EC. Part II: Compost quality; Separation*
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2.5
Separation of earthworms
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The vermicompost is a mixture of earthworms and compost, and
the earthworms have to be separated prior to their further
use. The earthworms will be separated from the cured com-
post by means of chemical attractants (smelling substances).
The compost, including the unhatched cocoons (egg-capsules),
will be held in controlled optimum conditions during the
weeks needed for the hatching of earthworms from the co-
coons. The newly hatched earthworms can be separated from
the compost by means of rotary screens.
In full scale the yearly earthworm production should be
about 46 tons.
The separation methods are still under development, and co-
operation exists with Andre Kretschmar (AFIDEL, France), who
is well experienced with the improvement of the separation
methods.
2.6
Compost products
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A building for laboratory, personal and administration faci-
lities, and for the processing and packing of the market
products, will be erected.
The compost will be sieved and mixed with peat and, if ne-
cessary, with fertilizers prior to the packing and sale. A-
nalyses and quality control will be carried out by Dansk
Erhvervsgartnerforenings Laboratorium, Aarhus, which has an
official authorization to carry out physical and chemical
analyses for the declaration of soil conditioners and growth
media.
The heat consumption of the building has been calculated to
be approximately 10 tons of oil equivalent per year; some 6
tons of oil equivalent per year will be gathered from the
composting heat plan. The remaining 4 tons of oil equiva-
lent will be produced by means of burning biogas produced in
the biogas reactor at the water line.
2.7
Testing of compost products
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The greenhouse and outdoor trials will be run in close co-o-
peration with Dansk Erhvervsgartnerforening (DEG) in Aarhus.
2.71
Greenhouse
A greenhouse of 400 sq.m. will be erected for the demonst-
ration trials, where the compost mixtures, made from the
composts produced by windrow composting and vermiculture,
will be tested. The size of the greenhouse has been chosen
so that one gardener will be able to run the trials in the
greenhouse as well as in the outdoor culture.
The trials will mainly be focused on the production of toma-
toes, cucumber, and paprika, but the cultivation of pot
plants will also be tested. The annual use of compost-peat
mixture in greenhouse production will be approximately 50
tons.
The annual heat energy consumption in the greenhouse will be
approximately 20 tons of oil equivalent. The composting
heat plant is able to deliver heat energy for the greenhouse
16 tons of oil equivalent, and the remaining 4 tons of oil
equivalent will be produced from biogas. Analyses and qua-
lity control will be carried out in co-operation with Dansk
Erhvervsgartnerforeningens Laboratorium, Aarhus.
2.72
Outdoor culture
The cultivation of different outdoor vegetables on various
compost mixtures will be tested in an area of approximately
2 hectares. Approximately 500 tons of compost-peat mixture
will be used annually. Analyses and quality control of the
plant products grown will be carried out in co-operation
with Bioteknisk Institut, Kolding.
3
DESCRIPTION OF THE WATER LINE
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3.1
Receipt of agricultural slurry
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The slurry will be piped from a farm located in the vicinity
(200 m away) of the plant. Most of the slurry will come
from cows (bovine feces and urine).
3.2
The separator
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The separator will divide the slurry into two fractions:
1) The fiber fraction, with solids content of about 25 per-
cent. It will be used for composting.
2) The liquid fraction, with solids content of about 2 per-
cent, but still with a high percentage of biodegradable or-
ganics. It will be treated in an anaerobic filter.
The type of the separator will probably be an angular adjus-
table screen with brushes on the screen part for cleaning.
This separator type will be simple and reliable.
(To be continued).