首页
登录
职称英语
Biogas: a Solution to Many Problems In almost all developi
Biogas: a Solution to Many Problems In almost all developi
游客
2024-08-08
13
管理
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 insect.
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: 36,000 are reported in rural areas of India, 27,000 in Korea and more than 80,000 in China. In most countries the value of the gas has been the prime factor leading to their adoption; 70 per cent 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 and to save compost materials from being burned.
In Japan and China, reducing pollution from animal wastes has been an important factor. Privies, hen houses and pigpens are bud! in proximity to the fermentation chamber in China. Examinations of the digested slurry have shown that the total number of parasite eggs was reduced by 93. 6 per cent, hookworms by 99 per cent and no schist some flukes were found.
The greatest benefits from biogas systems, however, are probably to be derived from the manurial value of the slurry, although it is not widely used outside of India and China. Vegetable farmers near Calcutta found that the digested slurry produced bigger and better tasting peas than did other fertilizers and the weight of root vegetables increased by nearly 300 per cent.
Summary
The production of biogas by fermentation of animal and vegetable wastes is a technology that has been largely developed and used in the【71】countries. Only very recently have scientists in the industrialized nations begun to show an interest—presumably because of the "energy【72】,". Family-sized-biogas【73】first came into widespread use in India in the 1950s in an effort to make a cleaner and more efficient use of cattle dung. The programme really expanded in the 1970s, and today there are as many as 100,000 plants throughout the world. Most are in domestic use to provide fuel for plants, but some larger units are operated in order to recycle wastes, supply fertilizer, control pollution and improve【74】. One Chinese study has shown that digestion of animal【75】in the airtight digesters greatly reduces health hazards from parasitic diseases. One Indian study has estimated that the value of the fertilizer obtained is in itself greater than the cost of producing the biogas. Thus, the system is economically sound, in addition to other benefits such as a cleaner, healthier environment. [br]
选项
答案
crisis
解析
从题干中的presumably(推测起来,大概)可知,该题属常识推理题。第四段,沼气事实上可以帮助conserving resources and finding alternative sources of fuel,可以猜想工业化国家对沼气感兴趣可能是由于能源危机,即energy crisis。
转载请注明原文地址:https://tihaiku.com/zcyy/3710502.html
相关试题推荐
Somepeoplearguethatthesolution______thedrugproblemiseducation,andwhil
Asolutiontothisproblemwon’tbeeasy,butwe’11seewhatwemanageto______.
Anglo-Saxonliterature,______,theOldEnglishliterature,isalmostexclusivel
Anglo-Saxonliterature,______,theOldEnglishliterature,isalmostexclusivel
Somepeoplearguethatthesolution______thedrugproblemiseducation,andwhil
ThomasMalthuspublishedhisEssayonthePrincipleofPopulationalmost200
ThomasMalthuspublishedhisEssayonthePrincipleofPopulationalmost200
ThomasMalthuspublishedhisEssayonthePrincipleofPopulationalmost200
Thesocialsciencesareflourishing.Asof2005,therewerealmosthalfamil
Thesocialsciencesareflourishing.Asof2005,therewerealmosthalfamil
随机试题
[originaltext]TheBritishForeignOfficesaysthemeetingisbeingcalledf
Thefoodandwaterthatpeople(consumethem)comefromtheenvironment,(provid
WhydoestelevisioncarrymorenationaladvertisingthananyothermediuminPor
水泥混凝土棱柱体抗压弹性模量试验方法规定,水泥混凝土的受压弹性模量取轴心抗压强度
某地区去年农村经济总收入构成如表2-2所示。 试做出分析并回答: 农村产
下列关于施工现场内特殊用房防火要求的说法中,正确的有()。A.建筑构件的燃烧性
软骨肉瘤采用的治疗方法是 A.化疗B.放疗C.根治性手术 D.化疗和根治性手
期货交易所办理的下列事项中,应当经国务院期货监督管理机构批准的是()。A.制定
维C银翘片的使用注意事项有A.过敏者禁用 B.禁高空作业 C.禁机器操作
根据《建筑法》规定,对从事建筑业的单位实行资质管理制度,将从事建筑活动的工程监理
最新回复
(
0
)