Plastics Recycling Technology in Japan

A discussion about plastic recycling techniques and Production of liquid fuel and solid fuel from plastic.

1. Introduction

 

The Japanese government promotes 3R policies in the country and to developing countries. However, there are many obstacles and discrepancies between the idea and reality. After the straggles in technologies and consumer movements over thirty years, a legislative approach to waste-plastic recycling started in Japan in the year 2000. The first target was plastic containers and packaging from household wastes. More than twenty years have passed, and we still face many problems within the country: high recycling costs, low quality of recycled resin with respect to the market value, and so on. Some of our challenges and achievements, or fact data itself would be good material for people that have an interest in waste plastics recycling.

 

2. Generation of waste plastics

 

Generation of waste plastics The Ministry of Environment of Japan announces the current status of generation and treatment of general wastes and industrial wastes every year. Municipal wastes of the total collection amount of 46.3 million tons include those produced from households (25.6 million tons) and those from small businesses (13.3 million tons). Waste plastic contents in municipal wastes are regularly monitored by each municipality. Depending on separation categories decided by municipalities, waste plastics are incinerated as mixed burnable wastes, or recycled like plastic containers and packaging. Some plastic materials such as those in toys and in electronic devices go to landfill. A composition survey of mixed wastes 202 Waste Management – An Integrated Vision that were brought into the Chuo incineration plant in Tokyo gave 16.0 wt% as a mean value of waste-plastics content in burnable wastes from households (fiscal year 2010). This mean value is an average of four times a year. For industrial wastes, waste plastic is one of 20 collection criteria of industrial wastes, and the recent survey shows the generation of 5.67 million tons in 2009.

The world plastics production is 265 million tons (2010). Production of typical synthetic resins in Japan (2010) is 12.2 million tons, and it accounts for 4.6% of the world production. The generation and the macro flow of the waste plastics in Japan are published annually by the plastic waste management institute. The total generation of waste plastics increased until 2004 (10.13 million tons), and gradually decreased to 9.12 million tons (2009) due to the shrinking economy in Japan. In 2010, the total generation increased to 9.45 million tons because of the recovery from the economic crisis in 2008.

There are the other sources of waste plastics. Recycling laws targeting various types of waste plastics would be considered based on the lifestyles of each country. Following to the recycling of waste plastics of containers & packaging, the more efforts will be considered to expand recycling activities. Substantial amounts of plastics are also used as daily commodities such as kitchen utensils and clothes cabinets. Plastics are also one of the main components of toys and E-wastes (wastes of electric and electronic equipment), which have been treated by landfill. Considerable amounts of plastic products are imported to the Japanese market. The amount of those imported plastic products is not clear. As an agriculture material, plastic film is a widely used product. Mulching, tunnel and green house are the typical uses in agriculture. Waste generation data from industry has been collected through questionnaire survey by the plastic waste management institute.

Waste plastics from general wastes such as containers and packaging contain various types of plastics such as a sheet, film, bag and bottle of polyethylene, polypropylene, polystyrene, polyamide and PET. And many items are laminates of two or more plastics, paper or aluminum. The recycling cost increase due to these complex compositions of mixed plastics as a feedstock of recycled resins. There are many business sectors buying thermoplastics of good quality for recycled resin production.

Waste plastics, especially polyethylene, propylene, polystyrene, PET and PVC, are exported to China over some 1.5 million tons per year. In 2011, 1.6 million ton of waste plastics of commercial values were exported to mainly China for mechanical recycling. China’s country share as the exporting destination is 1.48 million ton (90.5 % of total exported amounts from Japan), which includes the mainland 890 thousand ton and Hong Kong 586 thousand ton. Polypropylene is considered as the major component of the waste plastics defined as “the other plastics. “The mean price of the waste plastics is 46 yen/kg. It is varied depending on the conditions of wastes plastics. Generally, shredded, clean and colorless plastics are of the higher commercial value.

 

3. Technologies and businesses of waste plastics recycling

 

Recycled resin production

Recycled resin or recycled plastic goods are produced from 2.17 million ton of waste plastics. Some 1.6 million ton of waste plastics are exported. These plastics are considered to go to mechanical recycling. The difference between 2.17 and 1.6 million is about 600,000 ton, which is the feedstock for recycled resin in the domestic market. The domestic demands for recycled resin are quite weak than ones in China. Many Japanese manufacturers tend to avoid the use of recycled resin, especially from mixed waste plastics of containers and packaging because of the low quality such as strength, color and smell. As a result, the selling price of recycled resin pellets (typically, a mixture of polyethylene and polypropylene) from the mixed waste plastics is generally very low, 20 to 40,000 yen/ton, whereas the recycling cost of mixed waste plastics is 72,000 yen/ton in average due to the contamination of various components that are not suitable for the production of recycled pellets. The recyclers convert the separated portion of mixed waste plastics into recycled pellets or recycled products such as transportation pallets and imitation wood at about 45 wt%, and the rest goes to incineration with heat recovery or solid fuel production with paying gate fees. Some recyclers for plastic containers and packaging from general wastes make the efforts to raise the market value of recycled resin. There are three countermeasures for it. One is to change separation categories of waste collection by municipalities, for example, a separate collection of hard plastics like HDPE bottles and laminated soft plastics. The second is to introduce a sophisticated material sorting facility with optical sorting equipment under the cooperation with municipalities. Stable supply and constant production of recycled resin will be possible by the more precise selection of suitable plastics for mechanical recycling at the larger scale. The third is to develop a new application in cooperation with many companies in the wider business fields across many countries. To improve the quality of recycled resin, collection of hard plastic wastes and recycled resin production with hard plastic wastes were conducted as a research by Akita Eco Plash Co., Ltd. in cooperation with Akita prefecture and Noshiro city authorities based on funding by the New Energy and Industrial Technology Development Organization (NEDO).

 

Recycled resin has low melt-flow rate (MFR) because the original form of the polyethylene and polypropylene that recovered from C&P wastes is film and sheet. But the major products from recycled resin are not film or bag but hard plastic products. When hard plastic wastes of non C&P wastes were added to recycled resin of C&P at 10 %, the MFR was improved from 3.2 to 3.8. This result suggests the improvement of the qualities of recycled resin and products with reducing an additive. Minato-ward authority in Tokyo has a total collection system of plastic C&P wastes with the wastes of hard plastic products in the criteria of “Resource Plastics. “The collection of the wastes of plastic products increased the collection amount of polypropylene in hard plastic wastes [28], and it will help the MFR, which leads to the reduction of additives and cost reduction.

 

Home appliance manufacturers and automobile manufacturers are actively seeking the idea and technologies to raise the recycling rate of the waste plastics recovered from their wastes. Electric appliance manufacturers have been made efforts the cost reduction of their products. They took actions in recycling waste plastics in the products to reduce the waste amounts. Additionally, some companies started commercial operation of the precision separation system of some plastics by applying the difference of electrostatic properties of plastics. In 2010, Green Cycle Systems Corporation launched Japan's first large-scale, high-purity plastic recycling center under the technical and business support by Mitsubishi Electric Corporation.

The announcement states that Green Cycle Systems takes the shredded mixed plastic chips recovered by Hyper Cycle Systems and separates them into reusable plastic on a scale of unprecedented magnitude. And it also tells that the combined output of Plastics Recycling – Technology and Business in Japan 213 these two enterprises have increased Mitsubishi Electric's rate of recycled, industrial-grade plastic from 6% to a paradigm-shifting 70%.

 

Refuse-Derived Solid Fuel

 

There is a variety of solid fuel that has been prepared from wastes, which include wood, straw, rice husk, garbage from households, plastics and so on. To control moisture contents, some processes such as drying and carbonization are often performed. Any non-hazardous combustible wastes can be used as the raw material for solid fuel with or without preparation of pellets and briquettes. Preparation of pellets and briquettes contributes to constant quality of heating values, easy transportation and smooth feeding to a combustor such as a boiler. Table 9 shows the heating values of various combustible wastes and fuels . Waste plastics have high heating values, and coal substitutes can be prepared by mixing them with the wastes of low heating values. Thermoplastics act as a suitable binder, and paper, textile and thermosetting plastics can form pellets and briquettes despite to their properties that they are not solidified each other.

 

Due to the low heating value and high contents of ash and moisture, RDF is considered as low-quality fuel. There are not so many users of RDF except the power generation plants in the cooperation with municipalities. Different from RDF, densified solid fuel called as RPF (Refuse derived paper and plastics densified fuel) are popular as coal substitutes. Recently, the specification was defined in the Japanese Industrial Standards. It is produced by using paper, wood, plastics, textile and the other wastes. The raw material is dry and non-hazardous combustibles. It does not include any putrefactive wastes. About 1.6 million ton of RPF was shipped to, mainly, paper and steel manufacturers as coal-substitute for coal-combustion boilers in 2011.

 

Liquid fuel

Some thermoplastics, for example polyethylene, polypropylene and polystyrene, are thermally decomposed under an inert gas to yield liquid hydrocarbons at about 450 ˚C or above. The resulting liquid hydrocarbons have the similar heating values to those of fuels from petroleum. Decomposition products and fuel quality depends on the types of plastics and decomposition conditions. Polyamides and polyurethane give oily products of high nitrogen content at low yields.

Poly(ethylene terephthalate) known as PET does not give liquid hydrocarbon upon pyrolysis but solid products including terephthalic acid. Many types of reactors of tank, screw, externally-heating rotary kiln and fluidized-bed are developed. Some plants were used in demonstration, and some are commercially operated in Japan. Under the containers and packaging law, mixed plastics were converted into fuel oil through pyrolysis using a 20-ton/day tank reactor in Niigata and four 10-ton/day rotary kilns in Sapporo until recently. Those commercial operations were shut down due to the higher cost (about 80 yen/kg) than the other treatment costs like that of cokes oven treatment (about 40 yen/kg). However some recyclers bearing pyrolysis plants commercially produce liquid fuel from plastics of industrial wastes. Most recyclers have a tank reactor with a simple distillation system. In 2011, a recycler in Fukuoka prefecture started fuel oil production using a pyrolysis reactor with a paddle mixer. This reactor is commercially operated for 216 Waste Management – An Integrated Vision mixed plastics from a separate collection of municipal wastes. The product fuel mixed with commercial fuel at 1:1 is used for the boilers in public facilities.

 

Tasks for the future

Dissemination of recycling in the local societies and technology transfer to developing countries are of importance with respect to the promotion of the sustainability of the world. Life cycle assessment has been recognized as an important tool for judging how a certain product or a manufacturing process is green.

For the transfer of waste plastics recycling technology, the technology should be socially and economically accepted by the stakeholders in developing countries. Technology providers should develop the technologies of suitable specifications and easy operation with being aware of the local conditions. For example, a plant size should meet average collection amounts of target components of wastes. The average amounts 2.8 and 6.8 ton/day suggest a general idea of the suitable capacity of the equipment for waste treatment. In Japan, strict laws and regulations, a waste management company has to have a special permission in case that a treatment facility or equipment has a capacity larger than 5 ton/day. The permission is given by a prefectural government after strict check of planning, inspection of the entire facility including equipment, buildings and yard. In addition, consensus building with local residents is required as the one of conditions of the permission by the local government.

A long history of pollution problems and conflicts between a polluter and the local residents resulted in the severe conditions to both private companies and municipalities including waste management and recycling works.

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