By MIKI TANIKAWA
TOKYO — The mammoth earthquake and tsunami that resulted in the death of tens of thousands and wiped out coastal cities in northeast Japan left the region to deal with 25 million tons of rubble, perhaps the country’s biggest recycling challenge ever.
Experts say that much of the detritus — wood, steel, concrete and plastic — can be reused but that recovery efforts, like building shelters for those who lost their homes, are taking priority over the massive cleanup.
“The volume is simply daunting,” said Shinichi Sakai, professor of environmental engineering at Kyoto University. “It’s about half of what the Japanese households produce in waste annually.”
Before the debris can be cleared away, it must be searched for the bodies of the thousands of missing people buried by the earthquake or swept away by the tsunami, Mr. Sakai said. This is a laborious process that has to be done carefully before all the rubble can be disposed of in an environmental way.
According to the Environment Ministry, less than 20 percent of the debris left by the disaster has been sorted and transported to collection sites. Often, when more rubble is ready for transport, there is not enough space in collection areas, official said.
The debris differs from ordinary demolition waste or normal earthquake rubble because a lot of it is soaked in seawater that roared inland. Burning this kind of wood debris on the spot, which officials in many of the towns and cities in the affected area say will be necessary to clear away huge piles, is environmentally hazardous as it can generate carcinogenic dioxins.
Takashi Nakamura, an official from the Forestry Agency in Tokyo, said saltwater-soaked wood can damage incinerators when burned so it “must be desalinated to a considerable extent” beforehand. The National Institute for Environmental Studies in Ibaraki Prefecture said that exposing such wood debris to the elements, like rain, could wash out some of the saline content.
To assist in recycling the debris of wrecked houses and uprooted trees, which make up the majority of the detritus left by the disaster, the Forestry Agency will subsidize 50 percent of the cost of crushing machines that turn waste lumber and wood into chips that can be used as biomass fuel at biopower plants.
The agency set a goal of putting 10 percent to 20 percent of the waste wood into productive use, Mr. Nakamura said.
The recycling targets are low because most local governments in the devastated areas do not have the manpower or resources to carry out the full formula of collecting, sorting and recycling set out in guidelines drafted by the Environment Ministry after the disaster.
The areas most severely affected by the tsunami — Iwate, Miyagi and Fukushima, the three northeast prefectures facing the Pacific — are also struggling to find space to store debris and are falling far short of following standard practices, local government officials and experts say.
According to Environment Ministry estimates, as of May 17 the rubble that local governments have been able to pick up, transport and set aside at dump locations amounts to only a small portion of the total: 19 percent in Iwate, 14 percent in Miyagi and 11 percent in Fukushima. More than 200 sites have been set aside for dumping, but the ministry says many more are needed.
Land for dumping is scarce. The Miyagi prefectural government is so desperate for places to dump and incinerate the mountains of materials that it plans to use land adjacent to Matsushima, a picturesque group of islands considered one of “the three most beautiful places” in Japan and designated by the government as a special reserve.
To help in the cleanup effort, Mr. Sakai of Kyoto University said, “what you need is assistance in the disposal efforts from nearby cities and prefectures that weren’t affected” directly by the earthquake and tsunami.
One of the luckier cities is Sendai, the capital of Miyagi, the hardest-hit prefecture and the biggest producer of earthquake debris. The largest city in the region, Sendai will collect and reuse most of the debris, including large amounts of lumber waste from trees uprooted by the tsunami.
“It’s not clear if we can recycle all of them, but in principle we plan to turn woods into chips for fuel or recycle them as pulp materials,” said Kinya Imamura, an official in the environmental bureau of the city of Sendai. “We are getting various proposals from contractors right now.”
The city estimates that the heap of wood waste will amount to 230,000 to 250,000 tons. According to Mr. Imamura, the city is sorting the rubble and then transporting it to dumps. “There are mounds set aside for wood, concrete and steel and so forth,” he said.
Kenichi Shida, an official in the Environment Ministry’s disposal waste division, says not all municipalities will be able to comply fully with ministry guidelines for disposing properly of all the detritus.
“We have created the guidelines as a broad principle,” he said. “And there are local conditions that make it difficult for cities and towns to do what must be done.”
“In the case of Miyagi,” he added, “rubble removal in cities and towns other than Sendai” will probably have to be directed and coordinated by prefectural authorities, who in turn will need to be assisted by the national government.