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Home > NETT21 > Waste Recycling Technologies and Recycling Promotion Initiatives in Eco-towns in Japan

Data Entry: September 2011
Name of recycling technology Bio Gasification of Food Waste and Organic Waste from Food Manufacturing Industries, Food Retailers and Households, etc.
Name of recycler Japan Recycling Corporation
Location Chiba City, Chiba Prefecture
Name of eco industrial park Soga Ecology Industrial & Research Park
Receiving waste materials for recycling - Organic waste from food manufacturing industries (food processing waste, sludge, waste oil, waste acid, waste alkali)
- Food waste separately collected from households (a pilot project by the City of Chiba)
- Food waste and unsold food from large food retailers
Recycled products/recovered materials Methane gas (CH4: 60-70%, CO2: 30-40%, approx. 5,500-6,000 kcal/Nm3)
Capacity of recycling plant 30 t/day (solid concentration: 30%)
Area of recycling plant 10,000 m2
Number of employees in recycling plant 52 (as of November 2010, including employees of the adjacent waste gasifying and melting plant)
Start of recycling operation August 2003
Technical description
Methane gas is recovered from food waste and organic waste via anaerobic digestion.


Recycling process

The recycling process consists mainly of the following processes:

  • Pretreatment
    - First, the received waste is shredded to the size of about 3 cm.
    - Next, paper/plastic materials are removed by centrifugal separation and pneumatic separation and metals by magnetic separation from shredded waste.
    - Food waste is pulped into slurry with a wet grinding mill, and moisture is adjusted so that the solid concentration becomes about 10%.
    - Paper/plastic materials and fibrous materials remaining in the pulped slurry are then removed with a bar screen.
    - Removed foreign matter is treated at an adjacent waste gasifying and melting plant.
  • Sterilization
    - Food waste slurry is heated for more than one hour at 70°C to kill pathogenic bacteria, etc.
  • Anaerobic digestion
    - When food waste slurry is stirred in the digester at 37°C, organic matter is decomposed, and biogas with methane concentration of 60-70% is recovered (retention time: 20 days).
    - The biogas is desulfurized, and supplied to the adjacent JFE steel works to be used as fuel.
  • Post treatment
    - Digested slurry is dehydrated and dried, and then treated at an adjacent waste gasifying and melting plant to recover fuel gas and slag, etc.
Technological features
  • This plant can directly receive food waste and unsold food packaged in corrugated fiberboard boxes and plastic bags, recover only organic waste from the pretreatment process, and transport organic waste to the anaerobic digestion process.
  • This biogasification plant is located adjacent to a waste gasifying and melting plant and a JFE steel works.
  • The biogas recovered at this plant is used as fuel at the JFE steel works.
  • The electric power and steam required to run this plant are supplied from the JFE steel works.
  • Wastewater generated from this plant is transported to, and treated by, the JFE steel works' existing wastewater treatment facility.
  • Foreign matter and dehydrated/dried sludge generated from this plant is transported to the waste gasifying and melting plant for treatment to recover fuel gas and slag, etc. The fuel gas is also used as fuel at the JFE steel works, and slag is sold as a road construction material.
  • Through this process, the plant achieves zero emissions.
Background of starting recycling business and participating in eco-town program
  • Enforcement of recycling law
    In the past, food waste was incinerated or disposed of at landfill sites. However, the Food Waste Recycling Law (national law) was enforced in 2001, triggering high demand for recycling food waste.
  • Lack of waste disposal sites
    For years, there were shortages of waste disposal sites in the Tokyo Metropolitan Area including Chiba Prefecture, and therefore high demand to reduce the amount of waste disposal.
  • Management policy of the parent company
    At that time, the parent company (Kawasaki Steel Corporation, currently JFE Steel Corporation) was diversifying its business beyond steel manufacturing. In particular, the parent company was preparing to enter the environmental sector and waste recycling business in accordance with the corporate management policy, and so was actively conducting R&D.
  • Parent company's contributions to local communities
    After running the steel works for decades since the plant was constructed in Chiba City in 1951, the parent company (Kawasaki Steel Corporation, currently JFE Steel Corporation) was considering how to contribute to Chiba City and Chiba Prefecture by reducing the amount of waste disposal.
  • Established recycling technologies already available
    Through research and experiments, the parent company had already established technologies for producing biogas from organic waste before entering the recycling business.
  • High level of interest in the environment
    By using biogas as an industrial fuel, it is possible to reduce fossil fuel consumption and hence reduce CO2 emissions, a cause of global warming. Meanwhile, the generation of treatment residue can be completely eliminated by treating food waste in two steps in combination with the waste gasifying and melting plant adjacent to the steel works, thereby extending the service life of waste disposal sites. This business was expected to make a great contribution to society and the environment.
  • Initiatives of local government
    The Chiba City Government launched the Soga Ecology Industrial & Research Park Project, and solicited participation in the project.
    The initial investment in the business was about JPY1.4 billion. The company was able to receive JPY600 million from the national government, and some subsidies from the City of Chiba. The remainder was financed independently.
Fund procurement The initial investment in the business was about JPY1.4 billion. The company was able to receive JPY600 million from the nati
Major success factors
  • Combination with existing plants
    - The plant is located adjacent to the JFE steel works, which uses the biogas recovered in the recycling process as fuel. Electric power and steam required in the recycling process are supplied from the steel works, while wastewater generated in the recycling process is treated at the wastewater treatment facility of the steel works.
    - The company had already been running a waste gasifying and melting business on an adjacent site before starting the recycling business. Foreign matter removed or sludge generated in the recycling process at this plant is treated at this waste gasifying and melting plant.
  • Support from the parent company
    - The company received substantial investment from the parent company for the recycling business.
Issues and Challenges
  • Securing waste materials for recycling
    - The pretreatment process was improved so that food waste and unsold food packaged in corrugated fiberboard boxes and plastic bags can be directly received. This has enabled the plant to receive food waste and unsold food, etc. from large food retailers.
    - In 2007, the Chiba City Government commenced separate collection of food waste from households in some areas, and the plant receives this food waste after separate collection.
    - Turning food waste into biogas costs more than incinerating it, but an increasing number of private companies have been choosing biogasification following enforcement of the Food Waste Recycling Law and stricter requirements to reduce greenhouse gas emissions. To secure food waste, The company is committed to explaining to various private companies the benefits of biogasification for reducing waste and greenhouse gas emissions.
Future prospects
  • To stabilize operations and increase profitability, it is necessary to secure suppliers who continuously provide food waste of stable quantity and quality.
  • Because this business involves gas management, it is important to ensure complete safety in operating the plant.
    To ensure the continued success of the recycling business, local governments should continue to help secure waste materials for the recycling business.
Remarks To ensure the continued success of the recycling business, local governments should continue to help secure waste materials for the recycling business.

Reference:
H. Noma, K. Fukuda, K. Kamasuki; "JFE-Bigadan Biogas Process as an Energy Recovery and Digestion System," JFE Technical Report, No. 3. July 2004, pp. 35-40
http://www.jfe-steel.co.jp/en/research/report/003/pdf/003-07.pdf

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