City in Saitama cements plan for ultimate trash disposal

The Asahi Shimbun (a Japanese newspaper) reports on what seems to be just a cement-making process.



The city of Hidaka in Saitama Prefecture now views its garbage as a resource rather than just watching it go up in smoke. So the city has done away with incinerators and ash dumpsites and will begin using a specially modified plant to turn ordinary household garbage into cement.



Officials on Wednesday said the city’s garbage incinerating facilities ceased operations on Nov. 25 and that the nation’s first trash-to-cement plant will begin operation next month. They said the technology to make cement from household refuse-burnable garbage as well as nonflammables such as plastic, glass and chinaware-was developed in a joint project with Hidaka city and Taiheiyo Cement Corp.’s plant in the city. First, recyclables such as cans and bottles will be separated. All remaining garbage will be taken to the cement plant, where it will be exposed to hot air for three days. As the garbage ferments and breaks down, it will be mixed with lime and other materials and heated to 1,450 degrees until it becomes cement.



A plant technician said technology to remove salt from the garbage has been developed, since salt destabilizes the cement. Research began in 1993 when dioxin pollution became a national concern. Taiheiyo Cement, headquartered in Tokyo, conducted a 1.7 billion yen overhaul of its Saitama plant and has been conducting tests since March 2001. The process is not only the ultimate in recycling, but results in very low levels of dioxin, said plant officials.



Last year, dioxin levels and their related emissions measured only 0.0038 nanograms per cubic metre of emitted gas, they said. Using new emission standards taking effect in December, the maximum level allowed by the plant will be 0.1 nanogram per cubic metre.



The city will pay the plant 39,000 yen per ton (£205) of garbage processed. Having the garbage incinerated costs only 20,000 yen per ton (£158), but officials said overall costs will be reduced because the need for incinerating facilities and dumpsites for ashes has been eliminated