Special Issue

Recycling Technologies for the Sustainable Development

Review

Research and Development of Recycling Technology in National Research Institute for Resources and Environment

Abstract

National Research Institute for Resources and Environment has been devoted to the research and development of recycling technology since early 1970's and has demonstrated the usefulness of various waste recycling processes partly derived from mining technology.
In order to materialize sustainable development, Japan is trying to transform itself into a more recycling oriented society. It will not be achieved without excellent recycling technology. Close cooperation among industry, university and government is also necessary to seek out an optimum recycling system for the society.
National Research Institute for Resources and Environment is ready to organize the industry-university-government cooperation and would like to support the sustainable development technologically.

Key words: Recycle, Sustainable Development, Mining, Waste

(Language: Japanese)

Review

Distinction Techniques for Recycling and Reuse of Wastes

Abstract

Differentiation of waste is an important elemental technology that constitutes a resource circulation system for reuse and/or recycling of the scrap or removal of impurities in the waste, This report mainly introduces the techniques that distinguish solid waste on the basis of its multiple physical properties. I review the trend of materials and the deterioration state of optical properties (color, infrared spectrum, x-ray spectrum), electromagnetic characteristics and ultrasonic wave propagation, and introduce a detection system of those physical properties. At the same time, I introduce the sorting mechanism of the materials judged on the basis of the properties and the present situation of the identification/distinction efficiency. Finally, I describe the technical subject of such differentiation in the future.

Key words: Solid waste, Distinction, Reuse, Recycle, Color sorting, Infrared spectrum, Ultrasonic propagation

(Language: Japanese)

Review

Separation of Polyvinyl Chloride from Plastic Mixtures Using Air Table

Abstract

The amount of waste plastics in Japan in 1997 was 9.5 million tons. Most of that was )lust burned or used for land reclamation, and as small as 12% recycled. An important subject in society is now to minimize the amount of waste plastics for environmental health or elongation of service life of disposal sites.

Steel companies in Japan have a plan to utilize waste plastics instead of fine coals charged into blast furnaces. However, even slight amounts of polyvinyl chloride (PVC) in waste plastic mixtures generate the hazardous hydrogen chloride gas. For this reason, PVC should be separated as much as possible. Therefore separation of PVC in Plastic mixtures has been studied using an air table. The air table has a function to control the frequency of the shaking deck, the inclination angle, and air velocity. This paper describes the separation condition of the air table to obtain plastic mixtures of which PVC content is less than one percent.

Key words: waste plastic, air table, dry Process, Polyvinyl chloride

(Language:Japanese)

Review

Chemical Recycling of Plastic Wastes

Abstract

Annual production of plastics and the generation of wastes are first summarized and the properties of various types of plastics are characterized. Then chemical recycling of polyolefinic plastics by liquid -phase cracking and monomer recycling of thermosetting resins, such as phenol resin, epoxy resin, urethane resin, by cracking in the presence of hydrogen donor solvent are explained.

Key words: Chemical recycling, Liquid-Phase cracking, Polyolefinic plastics, Termosetting resins, Phenol resin, Epoxy resin, Polystyrene, Polyethylene

(Language:Japanese)

Review

Materials Processing for Recycling of Metals

Abstract

Further development of metal recycling techniques is essential for the human beings and industries in the new generation. At present, however, the recycling percentages of non-ferrous metals, e.g. copper, lead and zinc, are not high. To substantially raise them development of effective recycling processes for these metals from very complicated and contaminated wastes are very important. In NIRE research works on the recovery of useful metals from waste printed wiring boards and catalysts have been carried out. To minimize the amount of the complicated component sludge from surface finishing plants investigation of a new on-site water treatment system with novel solvent extraction processes is going. Further, cooperative research work on the direct recovery process of metallic zinc from the dusts of electric arc furnace is also proceeding.

Key words: recycling, wastes containing metals, highly complicated and contaminated wastes

(Language:Japanese)

Review

A consideration on the techniques and systems for municipal solid waste recycling
- on municipal bulky waste -

Abstract

Recycling of municipal solid wastes, which are composed of residential, commercial and industrial solid wastes except designated special industrial ones in Japan, is very important issue. This paper discusses the recycling of municipal bulky wastes, especially discarded large and heavy manufactured goods.

The following results by our research works are presented.

1. Nationwide questionnaire on municipal collection system for bulky wastes

2. Variations in composition and quantity of bulky wastes by a system change into a on-request and charged collection system in Sapporo, Japan

3. Characteristics such as shape and density of individual particles and ratio of metal particles to total, of incombustible residue discharged from resource recovery facilities of bulky wastes

Consequently the following suggestions are obtained.

1. In order to proceed from a crush and separated style to effective recycling of bulky wastes, a concept of inverse manufacturing is important.

2. A collection system via stores of manufacturing goods is cheaper than a municipal collection system.

Key words: on-reguest and charged collection, Waste composition, Crush and separation, Inverse manufacturing, Cost for waste collection

(Language:Japanese)

Review

Automobile Shredder Residue Compaction and Dry Distillation Demonstration Plat

Abstract

The Japan Automobile Manufaturers Association (JAMA) has been engaged in a study for the development of the technology for the disposal of automobile shredder residue (ASK) and demonstration of that technology through a full-scale plant in a four-year program initiated in April 1996.

The study used simulated ASR and was diuided into the following three phases:

Phase 1
In phase 1, JAMA built a full-size experimental facility for testing the urgently required separation, compaction, and solidification technology. In the end, it designed and built a new Extruder especially for ASR so as to develop commercial level technology.

Phase2
JAMA found that by dry distillation of the ASK compacted nad solidified at phase 1 by high temperature inert gas, it was possible to safely process the ASK by a simple, small-sized facility. It developed and demonstrated dry distillation and gasification technology with a top level of environmental performance as well.

Phase 3
JAMA conducted basic studies on the possibility of using the dry distillation residue remaining after Phase 2 as a carbon material and on the recycling of the residue for the aggregate material for cement ,by converting it into molten slag.

JAMA was able to confirm the feasibility of achievement of a 95% ASR recycling rate. It has summarized its findings in a detailed report.

Key words: Automotive General / Automobile Shredder Residue, Recycle, Dry-distillation, ASK Energy Recovery, Thermal Recycle

(Language:Japanese)

Original Paper

Analysis of water quality in Beppu Bay using an Ecosystem Model

Abstract

In order to analyze the seasonal variability of water quality in Beppu Bay, the nutrient cycling processes were simulated using an ecosystem model (a lower trophic model) based on the observational data of water quality collected from November 1994 to October 1995. The simulated results were in good agreement with the observational data for the whole year, except for some abrupt variability in July. Considering the model results in regard to nutrient limitation in the Bay, it was found that primary production was mainly controlled by nutrient availability throughout the year. In summer, when the nutrient load derived from terrestrial runoff was small and surface primary production was depressed by nutrient depletion, a phytoplankton bloom was observed following a large fresh-water discharge. Further, the observational data also showed high Chl-a peak after the abrupt fresh-water inflow due to heavy rainfall in July 1995. This bay was characterized by various species of phytoplankton competing for nutrients, and the phytoplankton biomass responded immediately to the fluctuations in the nutrient load. The amount of DOC produced by phytoplankton in Beppu Bay is estimated for summer and winter as 62%(12.9 ton/day) and 80%(0.8 ton/day) respectively. These estimates are considerably low compared with other eutrophic bays of Japan. Furthermore, in terms of nutrient dynamics, the limiting factor of primary production in the simulation was found to be nitrogen in Beppu Bay.

Key words: lower trophic model, annual simulation, primary production, nutrient

(Language: Japanese)