|Fig. 1: Katsushika Waste Incineration Plant located in Tokyo, Japan. (Source: Wikimedia Commons)|
Incineration is a waste treatment technology that involves the combustion of organic substances in waste materials with the objective of restoring energy. During the process of incineration, the wasted material is converted into IBM, gases, particles, and heat. These products are then used to regenerate electricity, creating potential for a sustainable cycle.  Despite controversies and environmental implications, the method of incineration has been rapidly growing throughout the world and Japan is one of the most noteworthy sites to examine this remarkable waste-to-energy revolution. Since 1965, Japan has been disposing municipal garbage through incineration and the country operates world's leading waste incineration facilities, with Tokyo's Katsushika Waste Incineration Plant (see Fig. 1) being the most noteworthy.  In fact, Japan dominates over 60% of the Asia-Pacific industry for Waste to Energy (WtE) incineration. The facilities throughout the country utilize various types of incineration methods such as stoker furnaces, fluidized bed furnaces, and gasification resource furnaces for the purpose of recycling ash. In Japan, stoker furnaces constitute 70% of all furnaces and its expansion as well as mechanical development is progressing. 
The specific procedures of incineration may not always be consistent among different WtE plants, but scrutinizing the overarching process is essential in understanding the various advantages and disadvantages of Municipal Solid Waste (MSW) incineration in Japan. The cumulated municipal waste is dumped into a large trash storage bunker. In order to eradicate odious odor, the air pressure within the plant is kept at relatively lower levels, so that fresh air from the neighborhood can enter and the incinerator can suck in the smell. Then, through the nitrogen oxide removal system, the waste is either burned to ash or steam. The ash is dumped in landfill and the steam is carried into the turbine generator that is operated at approximately 10-20 megawatt electricity. Following the mercury and dioxin removal system, the residue passes through the acid gas removal system. After the particles are filtered in the particulate removal system, they enter the final pollution control test. Water vapor and cleaned flue gases are released as renewable energy. 
Incineration of MSW has been controversial over many decades due to environmental and social reasons. One of the most significant concerns arising from WtE plants is the emission of furans and dioxins.  These chemical substances can be threatening to health if directly exposed to human bodies. Research has shown that furans and dioxins can cause cancer and change hormone levels. High levels of dioxin can also lead to a skin disease called chloracne.  Carbon dioxide, which is a green house gas that amounts to global warming, is another lethal byproduct from MSW incineration. Studies reveal that almost all waste materials containing carbon emits carbon dioxide during the process of incineration. Other gases that are emitted include sulfur dioxide, hydrochloric acid, fine particles and heavy metals. 
When the technology of incineration was first introduced, such detrimental byproducts were unidentified and government policies were not solidified to regulate WtE plants. However, many countries nowadays have reinforced environmental policies, and not only the Japanese government but also private sectors are improving the system to minimize environmental and social harm. Studies demonstrate that dioxin is produced when the combustion of waste is incomplete. Different measures have been enacted to inhibit the release of dioxin by enabling complete combustion of waste. These effective methods include exhaust cooling to prevent re-synthesis of dioxin, installation of bag filters to remove dioxin diffused in smoke, distribution of catalysts that decomposes dioxin, and the production of activated coal, which adsorbs and eliminates dioxin in exhaust fumes. 
Dealing with the aftermath of waste has been, and still is, a critical issue throughout the world. Converting waste to energy through incineration in Japan is technologically and environmentally advanced but the byproducts as well as other social issues must be taken into consideration. If national policies are thoroughly met, then the technology behind MSW incineration should be adapted in other countries that are particularly struggling with the obliteration of MSW.
© Hannah Park. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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