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Utilization of Food Wastes for Urban/Peri-Urban
Agriculture in Japan
GEN ISHOKA
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Utilization of Food Wastes For Urban/Peri-Urban
Agriculture In Japan
Gen ISHOKA
ABSTRACT
Large amount of municipal/industrial wastes is discharged in Japan and
critical state of final disposal site emerged. Japanese government shifted the policy to
establish a "Sound Material-Cycle Society" and "Reduce, Reuse, Recycle" of waste is
requested. Under such circumstances, reuse and recycle of food waste is requested in
agriculture. Utilization of fertilizers and feeds made of food waste and utilization of
the effluent of methane fermentation of food waste can contribute, but there are many
constraints to hamper recycle especially for the garbage from household.
Keywords: municipal waste, garbage, compost, feed, effluent, methane fermentation
INTRODUCTION
Japanese society and government used to give highest priority to advancing
its economic development. This policy enhanced mass production, mass consumption
and mass disposal. As a result, amount of discharged waste increased year by year and
waste disposal site said to be full in several years. This situation led Japanese
government shift their policy to turn Japanese society more environmentally sound,
and "Fundamental Law for Establishing a Sound Material-Cycle Society" was enacted
in 2000. Several laws concerning recycling, such as "Food Waste Recycling Law,"
were enacted and enforced subsequently. Then started "3Rs" policy, "3Rs" means"Reduce, Reuse, Recycle", in order to create a sustainable society: one that has
balance between the environment and the economy. Under such circumstances, reuse
and recycle of food waste is requested in agriculture, as most of the food waste is
agricultural origin. Generation of food waste is more in urban area than rural area.
Thus urban/peri-urban agriculture should contribute more in reuse and recycle of food
waste.
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STATE OF DISCHARGE OF SOLID WASTES AND RECYCLING
OF FOOD WASTE IN JAPAN
State of discharge of municipal/industrial solid waste
Solid wastes are classified into two categories in Japan: municipal and
industrial. The disposal of municipal wastes is the responsibility of the municipalities.
The disposal of industrial wastes is the responsibility of the entities that generate the
wastes.
In FY 2003, the amount of discharged municipal solid waste was 51.61
million tons in total and 1.106 kg/capita per day. These figures have not changed
much in 15 years (Fig.1). Household waste was 34.66 million tons (67.2%) and
business waste was 16.95 million tons (32.8%).
Method for final disposal is landfill in Japan. Direct landfill is 1.86 million
tons (3.6%) and landfill after reduction by intermediate treatment (e.g. incineration) is
6.59 million tons (12.8%). Amount of landfill decreased gradually from 1994-2003,
largely due to decreasing volume of direct landfill (Fig. 2).
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2 4 6 8 100
5
10
15direct landfilllandfill aftertreatment
'94 '95 '96 '97 '98 '99 '00 '01 '02 '03 FY
millionton
s
Fig. 2. Amount of final disposal (municipal waste) in Japan,FY 1994 - 2003
Source: Ministry of the Environment
2 4 6 8 100
50
100
150
200
'94 '95 '96 '97 '98 '99 '00 '01 '02 '03 FY
millioncubic
meters
Fig. 3. Remaining capacity and lifetime of final disposal site(municipal waste) in Japan, FY 1994 - 2003
remaining capacityremaining lifetime
0
5
10
15
20
years
Source: Ministry of the Environment
Remaining capacity of final disposal sites for municipal solid waste is 137.08
million cubic meters and remaining lifetime is 13.2 years. The remaining capacity
decreased steadily in these several years but the remaining lifetime increased slightly
(Fig.3), as the amount of landfill decreased (Fig. 2).
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Total amount of discharged industrial waste is approximately 412 million
tons, this figure has not changed much in 15 years (Fig. 4). Three major sources
accounted for more than 60%, i.e. electricity, gas, heat and water supply (92.25
million tons, 22.4%), agriculture (90.59 million tons, 22.0%) and construction (75.01
million tons, 18.2%). Sludge accounted for 46.3% (190.38 million tons), followed by
excrement of animals (88.98 million tons, 21.6%) and debris (59.25 million tons,
14.4%).
48.9% (201 million tons) of industrial waste is recycled and 43.7% (180
million tons) undergoes reduction. Final disposal is 30 million tons (7.4%). Amount
of final disposal decreased steadily in these 10 years (Fig. 4). Highest recycle ratio is
scored by excrement of animal, 93.8%, and most of them turned into livestock waste
compost.
Remaining capacity of final disposal sites for industrial solid waste is 184.18
million cubic meters and remaining lifetime is 6.1 years. The remaining capacity
decreased steadily in these several years but the remaining lifetime increased slightly
(Fig.5), as the amount of landfill decreased (Fig. 4).
2 4 6 8 10 12 140
100
200
300
400
500
'90 '92 '94 '96 '98 '00 '02 FY
milliontons
Fig. 4. Amount of industrial waste in Japan, FY 1990 - 2003
Source: Ministry of the Environment
total volumefinal disposal
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2 4 6 8 100
50
100
150
200
'95 '96 '97 '98 '99 '00 '01 '02 '03 FY
millioncubicmete
rs
Fig. 5. Remaining capacity and lifetime of final disposal site(industrial waste) in Japan, FY 1995 - 2003
remaining capacityremaining lifetime
0
5
10
15
20
years
Source: Ministry of the Environment
State of food waste recycle
Other than commonly used livestock waste compost, waste that can be
applied to agriculture is food waste. It includes garbage of household and waste from
food related business, i.e. food manufacturing, food distribution, food sales and
restaurant/catering. Only the waste from food manufacturing is categorized into
industrial waste, others are categorized into municipal wastes.
Discharge from food related business is 11.358 million tons in FY 2004 and
the amount recycled is 5.793 million tons. Total amount have not changed much since
2000, but the recycling rate gradually increased and it exceeded 50% in FY 2004
(Fig. 6).
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2 40
5
10
15total volumerecycled volume
'04'00 '01 '02 '03 FY
millionto
ns
Fig. 6. Amount of food waste in Japan, FY 2000 - 2004Source: The Ministry of Agriculture, Forestry and Fisheries
Table 1 shows amount of food waste and recycling type of each food related
business. Food manufacturing is most in amount and highest in recycling rate. As
business scale turns smaller, recycling rate decreases.
One important constituent of food waste not listed in Table 1 is garbage from
household. Estimated volume of the garbage is about 10 million tons in FY 2003. The
amount is gradually decreasing, but still it is as much as total discharge from food
related business (Fig. 7). More important is the recycling rate. In FY 2002, only 1.8%
of garbage from household said to be recycled, contrary to the food waste of business
origin in municipal waste, 24%.
Table 1. State of Food Waste Recycling
total volume
(million tons) (million tons) (%) fertilizer feedmethane
fermentation
fat/fat
product others
manufacturing 4.898 3.80 78 46 35 0 3 16
wholesales 0.751 0.40 53 28 38 0 1 33
retail 2.604 0.82 32 30 36 0 7 27
restaurant/catering 3.194 0.77 25 22 20 1 6 51
total 11.358 5.79 51 39 33 0 4 24
recycled volume type of recycle (%)
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2 40
10
20
30
40
'03'99 '00 '01 '02 FY
milliontons/
%
Fig. 7. Amount of waste and garbage from householdin Japan, FY 1999 - 2003
Source: Ministry of the Environment
total volume from householdestimated percentage ofgarbageestimated volume of garbage
UTILIZATION OF RECYCLED FOOD WASTE IN JAPAN
Among the types of recycle listed in Table 1, fertilizer, feed and effluent of
methane fermentation can be utilized for agriculture. Over all, separation of the
materials not suitable for farmland application, such as plastics and pull-tabs, is the
largest problem, especially for the wastes from household and restaurant/catering.
Separation machine is installed in some facilities, but separation at the source, for
example kitchen and table, is necessary. It requires consciousness from all of us.
Another problem is offensive odor and pathogen, which compels immediate
treatment. Variation in volume and constituent also restricts utilization. As it is
difficult to control these issues on waste from household, recycle and reuse is limited.
Fertilizers
Wide variety of garbage processing machine is sold in Japan. For household
use, which handles 1 to 3 kg at one time, price is above $300 and many municipalities
set subvention for purchasing. For business use, capacity varies from 10kg to more
than 500kg and so is the price, usually more than $10000. Type of treatment is
dehydration and or fermentation. Fig. 8 shows crude fat content of processed
garbage from school-provided lunch in Mie Prefecture. Even the treatment type is
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fermentation, a lot of crude fat remains, meaning these garbage processing machine
cannot complete fermentation. Application of immature compost may cause severe
damage to plant growth. It is not advisable to use this kind of treated garbage directly
to agriculture.
2 4 6 8 10 12 14 16 18 200
5
10
15fermentationdehydration
%
Fig. 8. Amount of crude fat in processed garbageSource: Mie Prefecture Science and Technology Promotion Center
One solution for this issue is nitrogen addition. Tokyo University of
Agriculture operates garbage dehydration and pelletization facility which can add urea
into the pellet (Goto I. 2005). Additional nitrogen from urea avoid nitrogen deficiency
in soil (Fig. 9). It is not only nitrogen deficiency that causes damage, but even after 5
years of application (N-P2O5-K2O = 4-1-1, 1t/10a), no damage has observed. Salt
content is 0.8-2.1% and it is not harmful as far as using outside of greenhouse. The
facility produces 70kg of fertilizer from 500kg of garbage from restaurant in the
university, schools and supermarket nearby. Their plan was utilization in the farmland
of the district, about 140 ha, but could not be achieved. What hampers utilization is
the impression that it is made of "garbage", despite it is rather "clean" biologically as
it becomes about 90C during the dehydration process. Collaboration work with some
comprehensive farmer to prove harmless is necessary.
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Another solution is secondary treatment to complete fermentation. There are
several compost plants for garbage or dehydrated garbage. Some of the compost
plants for livestock waste accept garbage. Garbage contains high amount of fat,
protein and starch. These constituents are easily decomposed by microorganisms and
the decomposition process requires oxygen. This means regular mixing and aeration is
necessary and it takes longer period to complete fermentation.
Even after complete fermentation, the impression of "garbage originated" and
worries about salinity hampers utilization. Some of the franchise chains of restaurant,
convenience store resolve this issue by promising to purchase agricultural products
using the compost from the franchise chain.
Feeds
It is necessary to take extreme care on sanitary and quality when one turns
food waste into feed of livestock. Waste from food manufacturing industries, such as
crumbs of bread, residues of alcoholic fermentation and juice, is easier to control
quality, quantity and purity, therefore they are widely used. Waste from the other type
of food related business is also possible to turn into feed if separation of trash is
achieved.
In City of Sapporo, Hokkaido, garbage from food manufacturing factory,
supermarket, hotel, school, hospital and restaurant is collected by a public corporation
and a company processes and sells as a material of mixed feed. Garbage from
household is not included.
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In City of Nagaoka, Niigata, NPO conducts recycle of garbage from
school-provided lunch to livestock production in the district. The system is highly
dependent on participants, i.e. kitchen staffs of school and livestock farmers, and
volunteers who transport garbage from school to farmer. Kitchen staffs are
responsible for separation and farmers are responsible for manufacturing feed by
fermentation. An important point at the separation is feed for bovine cannot contain
meat and fish.
There are several progressive examples like this, but the number is still
limited due to the difficulties on controlling quality, quantity and purity. Feed made of
garbage is high in fat. It makes fat in pork softer and degrades quality. Farmers have
to recognize the quality of the feed and control it by mixing with the other kind of
feed. For about purity, relationship between waste producer and consumer affects.
Successful case tend to have producer and consumer known each other. In such case,
producers try their best to meet consumer's demand.
Methane fermentation
Methane fermentation, which produces methane from livestock waste or
garbage by anaerobic digestion, produces effluent as by-product. In many cases, the
effluent is treated as sewage. This means separation of solids, denitrification or
dilution to meet water quality standard is operated with extra cost. The effluent
contains 0.2-0.5% nitrogen, 0.2-0.4% potassium and 0.1-0.2% phosphate. Although it
is dilute, still agricultural use is possible.
The main constraint for agricultural use is that the effluent is liquid. This
means some method for transport is necessary. Solid material content is usually less
than 10% but it is difficult to transport with ditch or pipe. In order to apply 10kg of
nitrogen in 10a, the amount of the effluent with 0.2% nitrogen is 5 tons. Only with the
vehicle with huge tank can manage.
Another constraint is offensive odor. Although it smells far better than slurry
or rotten garbage, it is not acceptable to spread large amount of the effluent onto the
top of soil, especially in the urban area. It can be avoided with injection into soil or
immediate covering with soil, which requires special apparatus. One good utilization
method is spreading into paddy with water. Dilution of the effluent reduces offensive
odor.
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In Japan, interest in organic agricultural products grows more and more these
days. Farmers can apply livestock waste compost as basal dressing, there was no good
organic fertilizer for top dressing. The effluent of methane fermentation would be
useful. It is difficult to meet the criteria of Japanese Agricultural Standard for Organic
Agricultural Product, but it is suitable to meet the demand for "Specially Grown
Agricultural products", which requires reduction of chemical fertilizers and pesticides
by 50%.
Methane fermentation is operated at 35C or 55C. Temperature is lower than
composting or dehydrating and pathogen may not die out. Carbonate and alkali said to
eliminate E.coli form dairy cattle manure (Diez-Gonzalez et.al. 2000), precise
condition to eliminate is not confirmed. The effluent of methane fermentation is
usually pH 7.5-8.0 and contains high amount of carbonate (100-200mM). More study
on this topic is needed.
Methane fermentation plant of large scale costs several million dollars to
build and several hundred thousand dollars to operate. But it does not cost much to
keep the minimum requirement, anaerobic condition. In Ogawa town, Saitama, NPO
made small scale facility of strong plastic sheet and compressed panel, which costs
about $14000 (Fig. 10). Garbage is collected from household in exchange of local
currency. The effluent is applied to paddy and vegetables, which can be purchased
with the local currency.
Fig. 10. Methane fermentation plant of NPO Foodo, Ogawa Town
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REFERENCES
Diez-Gonzalez F., Jarvis G.N., Adamovich D.A., Russell J.B. 2000. Use of carbonate
and alkali to eliminate Escherichia coli from dairy cattle manure.
ENVIRONMENTAL SCIENCE & TECHNOLOGY 34 (7): 1275-1279
Development of high quality composting system using garbage treated materials.
2005. Report for Research project for utilizing advanced technologies in
agriculture, forestry and fisheries. (in Japanese)
Goto I. The trial of community-based garbage recycling in Setagaya-ku Tokyo. 2005.
SOIL MICROORGANISMS 59 (2): 111-115 (in Japanese)
State of Discharge and Treatment of Industrial Waste in FY 2003. 2005. Ministry of
the Environment, JAPAN
State of Discharge and Treatment of Municipal Solid Waste in FY 2003. 2005.
Ministry of the Environment, JAPAN
State of Recycling of Cyclical Food Resources. 2005. The Ministry of Agriculture,
Forestry and Fisheries, JAPAN