Biogas; a Solution to Many Problems In almost all developing countries, the lack of adequate supplies of cheap, convenient and r

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问题 Biogas; a Solution to Many Problems
In almost all developing countries, the lack of adequate supplies of cheap, convenient and reliable fuel is a major problem. Rural communities depend largely on kerosene, wood and dung for their cooking and lighting needs. But kerosene is now priced out of reach of many people and wood, except in heavily forested areas, is in short supply. The search for firewood occupies a large part of the working day and has resulted in widespread deforestation.
Dung is in constant supply wherever there are farm animals and, when dried, it is convenient to store and use. But burning dung destroys its value as fertilizer, thus depriving the soil of a much needed source of humus and nitrogen.
Rural areas of developing countries are also plagued by a lack of adequate sanitation. Improper waste disposal spreads disease, contaminates water sources and provides breeding grounds for disease—carrying insects.
The problems of improving environmental hygiene, conserving resources and finding alternative sources of fuel may be unrelated. Their solutions, however, are not, as many countries experimenting with biogas technology are discovering. Biogas, a mixture of methane and carbon dioxide, is produced by the fermentation of organic matter. The process of anaerobic fermentation is a natural one, occurring whenever living matter decomposes. By containing the matter—and the process—in a digester or biogas plant, the combustible gas can be trapped and used as fuel for household lighting and cooking. The digested slurry that remains can be used on the land as a soil conditioner and fertilizer.
Biogas plants have attracted much interest in recent years and they are in use in several Asian countries; 36000 are reported in rural areas of India, 27000 in Korea and more than 80000 in China. In most countries the value of the gas has been the prime factor leading to their adoption; 70 percent of India’ s plants, for instance, were built during the energy and fertilizer crisis of 1975-1976—although their use in that country dates back to 1951. Similarly in Thailand and Korea, biogas is being investigated as an alternative to costly charcoal ad to save compost materials from being burned.

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答案 沼气:一举多得 在几乎所有的发展中国家,缺少经济、方便、可靠的燃料源是个大问题。农村地区大部分依赖于煤油、木材、家畜的粪便以满足他们做饭照明之需。但是现在煤油的价格已使很多人可望而不可及,而除了在森林茂密的地区,木材也是供应短缺。寻找木材占据厂工作日的很大一部分时间,造成了大面积的森林破坏。 在任何有家畜的地方,粪便都会源源不断,当其干了之后,便于储存使用。但是,烧了它会破坏其增肥的价值,因此使土壤失去腐殖土和氮这些极需的原料。 发展中国家的农村地区还深受卫生设施体系不完善的困扰。不合理的废物处理传播疾病,污染水源,给疾病携带昆虫提供了寄生之所。 诸如提高环境清洁卫生,节约资源,寻找燃料替代品等问题,也许毫不相干。但是,正如许多做沼气技术实验的国家渐渐发现的那样,他们的解决方法并非毫不相关。沼气,是甲烷和二氧化碳的混合物,是有机物发酵后产生的。厌氧发酵是自然过程,任何生物腐烂时都会发生。在沼气池或沼气厂内装上此物质,进行这个过程,然后就可以收集可燃气体并且用于家庭照明和做饭。发酵后的浆液可洒在地上,用作土壤改良剂和化肥。 近些年,沼气厂已吸引了广泛关注,并已在一些亚洲国家投入使用:据报道,印度农村地区有36000家,韩国有27000家,中国有80000多家。沼气的价值是大多数国家建沼气厂的主要原因:比如,印度70%的沼气厂建于1975年至1976年间的能源和化肥危机,尽管沼气的使用可追溯至1951年。同样在泰国、韩国,据调查,沼气是花费较高的木炭的替代物以减少燃烧堆肥物质。

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