Resources and Conservation最新文献

The increasing arisings of municipal solid wastes constitute a serious environmental problem for the developing countries. Urbanisation has magnified the need for adequate solid waste disposal. This article examines the present situation of solid waste management in Indonesia in general and Jakarta in particular. The available disposal methods are presented and analysed, while possible options to improve the overall management of wastes are discussed on the basis of the available technologies. These are evaluated in terms of compatibility with the wastes produced in Indonesia.

The history of refuse-derived fuels (RDF) is reviewed from the earliest recorded use of municipal solid waste in its as-discarded form as a fuel to generate steam. (Today, such fuel is termed RDF-1.) The first use was during the last quarter of the nineteenth century, apparently in England. The technology was quickly adopted in the United States, Germany and Japan. In New York City, in the 1890's the solid waste was hand-picked to remove useful materials and the residue became another form of RDF which was burned to generate electricity. Early adaptations of English mass burn technology in the United States near the turn of the century were fraught with frustration and failure and many of the early plants were closed.

Reports of using prepared waste as a fuel in the United States during the first half of this century are reviewed, as are the early modern developments of processing wastes to various forms of RDF. Also reviewed are the early contributions of the U.S. Bureau of Solid Waste Management, the Bureau of Mines, the National Bureau of Standards, and the American Society for Testing and Materials, and early legislation leading to the U.S. Resource Conservation and Recovery Act (RCRA). Finally, a discussion of lessons learned from this history, as they pertain to current developments, is included with a description of the rate of growth of resource recovery since 1974. The rate of growth is compared to a derived analytical expression useful for estimating future processing capacity.

Natural salt lakes with temperature gradients are briefly reviewed. Previous work on artificial solar ponds for energy production is also examined. The experience gained from more than twenty non-convecting solar ponds encourages their economic utilization in the future. In addition to the technical and physical requirements for solar pond construction, four basic requirements (sunshine, land, water and salt) are pointed out. In Turkey, these are abundantly found. Salt is the most important and expensive element, constituting about 15–20% of the initial investment of a solar pond. Salt can also be regarded as a complementary “fuel” for a solar pond, since it should be continuously replenished during the operation of the system. In this respect, salt resources in the country were studied. It is recommended that a survey over the Salt Lake be carried out to discover possible natural temperature gradients for heat generation.

Pyrolysis processes have been proposed for converting tire wastes into valuable products, particularly through gas-solid contact in various reactor designs. In this paper, the pyrolysis reaction is analyzed in terms of physical and chemical kinetics. A specific method is described for experimentally studying the kinetics of pyrolysis of tire chips. Pyrolysis time is examined as a function of temperature and sample size for determining limitations of the process: heat transfer and chemical kinetics. Conversion curves are modelled and discussed. As a technical basis for evaluating the realistic potential of any industrial batch process, pyrolysis of used tires is studied in a pilotscale unit (100-L retort reactor). Results of material balances as well as quality of products are presented.