# Column : Donating Used Equipment to Developing Countries

The collection and transport of waste is the first step of waste management, but in developing countries the system is insufficient to deal with all waste generated, resulting in waste being left on roadsides or street corners. To solve this problem, various activities are being conducted to transfer used, but still working, waste collection vehicles of Japanese local authorities to developing countries that require them. For example, 10 used waste collection vehicles of Osaka City were donated to Phnom Penh, Cambodia, under grass-roots grant aid for recycling. Although donating used vehicles is worthwhile, international cooperation will have greater value if technologies for maintaining the vehicles or effectively collecting waste are also transferred to recipient countries.

Japanese waste collection vehicles donated to Phnom Penh

Source: Overseas Environmental Cooperation Center

force. For transportation of bulky waste or for transportation to a transfer facility, various types of vehicles, such as tippers and trucks with cranes, are used.

Collected domestic waste is transported directly to an intermediate treatment facility, such as an incineration plant, or transported to a transfer facility and transferred to a larger vehicle when the distance to a treatment facility is great. Besides collecting and transporting waste with a vehicle, there is also pipeline waste transportation technology that transports waste through a pipeline with compressed air, but this is not widely used today because of difficulties with waste segregation.

In developing countries, because of narrow roads that cannot accommodate waste collection vehicles and because the cost of labor is comparatively low, waste is manually collected by humans in many areas.

## (3) Intermediate treatment technologies, such as incineration

After being collected and transported, waste is subjected to intermediate treatment, such as incineration, composting, shredding and compaction, so as to become suitable for final disposal, including landfilling, or reuse. Thanks to such intermediate treatment, the volume of waste is reduced, stabilized and rendered innocuous.

Incineration is generally used in Japan for intermediate waste management. Because incineration reduces the volume of waste very effectively and destroys disease-causing bacteria, it is suitable for use in a country such as Japan where it is difficult to secure final disposal sites, due to limited land space, or where the temperature and humidity become high in summer. It is estimated that when incinerated, waste is reduced to approximately one-tenth of its weight and one-twentieth of its volume. In 2005, the amount of domestic waste generated was approximately 53 million tons, approximately 80% of which was incinerated.

Because the amount and quality of waste generated and the measures required for environmental preservation have changed, incineration technology as a core waste management method has developed accordingly. Because domestic waste in Japan has a comparatively high water content, advanced technology is required to achieve its complete combustion. By overcoming various challenges, incineration technology in Japan has attained the highest level in the world.

The enforcement regulations of the Waste Management Law define a structural standard for incineration plants for domestic waste, in which it is required to keep combustion gas temperatures above $ 800^{\circ} $ C for incineration, to keep the temperature of gas flowing in the dust chamber below $ 200^{\circ} $ C and to provide a waste gas treatment facility, etc. When classified by operating mode, there are three types of incineration plant: a batch fed incinerator is operated for 8 hours per day; a semi-continuous feed incineration plant is operated for 16 hours per day; and a full continuous type incineration plant is operated 24 hours per day (Fig. 2-5). When classified by the shape of the furnace, incineration plants are roughly grouped into 4 types: mechanical stoker type incinerators (Fig. 2-4) where a metal fire grate called a stoker is moved mechanically to transport and agitate waste and air is supplied from under the fire grate to burn waste; fluidized bed incinerators, where air is blown into a high-temperature sand layer to make it flow and waste is loaded into it and burnt; fixed floor furnace type incinerators where there is no fire grate and waste is burnt on a floor composed of refractory material with a flat recession; and rotary furnace type incinerators (rotary kilns) where a horizontal cylindrical incinerator, the inner