Pig Manure as an Energy Source Final Processing Facilities Are Full Farewell to Dioxins

Final Processing Facilities Are Full

As a country with few natural resources, Japan is self-sufficient by 20% in its own energy supply and imports close to 100% of its crude oil. For this reason, Japanese companies and research organizations have concentrated on developing energy-saving technologies over the years. It is no coincidence that Japanese cars achieved the world’s best fuel economy after the oil crises. We can say that industrial waste recycling technologies are an extension of these technologies. There are 130 million people on a small islands in Japan. In the mass-production, mass-consumption culture of the second half of the 20th century, Japan has been consuming and disposing a lot. This has resulted in a shortage of processing capacity in waste disposal facilities—Japan is running out of places to put its waste. The problem is becoming severe with regard to waste disposals from construction works. Construction sites in Japan produce a collective 85 million tons of waste disposals per year, accounting for around 20% of total industrial waste. Meanwhile, the space for landfills have been filled with disposals, with only 4.3 years’ of space left nationwide. Against this backdrop, the Construction Material Recycling Act went into effect in May 2002. Under the act, construction waste generated in the process of building and dismantling buildings over a certain size must be sorted into categories and recycled at the sites. Sumitomo (S.H.I.) Construction Machinery’s “Garaxy”, a self-powered mobile crusher for gara (which means rubbles of concrete, asphalt, etc), is designed to meet this very need.

	Transformed Quickly into Resource
	Waste disposal before and after Garaxy processing. The system crushes concrete and asphalt chunks into particles between 0-80 mm in diameter. The output size can be adjusted.	A large hopper measuring approximately 2 m by 2 m is mounted atop the Garaxy’s body. Lumps of concrete, asphalt, etc., generated from construction work are thrown into the hopper to be crushed into tiny, pebble-size pieces 0-80 mm. Steel bars and metal fragments are removed by powerful magnets after the crushing process to produce a recycled aggregate of consistent particle size, which can be reused as the base for road and building construction. Other construction machinery manufacturers have also commercialized crushers, but these are jaw crushers that crush waste materials by the impact of hitting a heavy steel plate. The Garaxy crushes by placing the material between rollers with metal bits like large teeth that grind the pieces down. Says Sumitomo (S.H.I.) Construction Machinery Sales Executive Officer Kouji Arima, “It is difficult to crush pieces of asphalt that have softened in the heat with jaw crushers, whereas roll crushers can grind them down without them sticking. Jaw crushers are quite noisy because they vibrate a lot from the impact, but roll crushers are low-vibration and much quieter.”

	Soil Improvement on Construction Site
	The Construction Material Recycling Act’s basic premise is on-site disposal, which is why Garaxy is a crawler-mounted, self-powered system. Developing a self-powered system presented its own problems, as Arima explains: “You have to transport the crusher to the site on a trailer, which requires passing under rail and foot bridges, which impose a height restriction. Since there is a certain height requirement for the hopper, designing the crusher with the height restriction in mind was quite a challenge.” Another product that make it possible to recycle the waste disposals at the sites is the Resoilman Hyper—a self-powered soil improver that dries and strengthens soil dug up in the construction process by mixing it with lime and cement. As one example, soil that is excavated in dredging work cannot be used as-is because it is too wet; but processing it with the Resoilman Hyper lowers the moisture content from 100% to around 50%. Once the moisture content has been reduced to this level, the soil can be left to dry for a few days and then used for civil engineering applications. Transporting wet soil is difficult, but soil processed by the Resoilman Hyper can be transported straight away. “Lime is a mineral, so it has no adverse effect on the environment when mixed with soil,” explains Arima. “The internal temperature of the soil rises to 70-80°C after lime is added to the system, almost to the point that it starts to steam.” The Resoilman Hyper went on sale in spring 2004 and uses a proprietary four-axle cutter technology. Pinnate revolving cutters similar to those found in cultivators ensure efficient mixing of soil regardless of high moisture content. The company plans to make this model the mainstay product, although it has already introduced a second model in the Resoilman line.	Kouji Arima, Executive Officer, Sumitomo (S.H.I.) Construction Machinery Sales