首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Biogas: a Solution to Many Problems In almost all developing countries, the lack of adequate supplies of cheap, convenient a
Biogas: a Solution to Many Problems In almost all developing countries, the lack of adequate supplies of cheap, convenient a
admin
2013-02-03
29
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 built 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 schistosome 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【61】countries. Only very recently have scientists in the industrialized nations begun to show an interest--presumably because of the "energy【62】". Family-sized-biogas【63】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【64】. One Chinese study has shown that digestion of animal【65】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.
选项
答案
cooking and lighting
解析
(第四段,…the combustible gas can be trapped and used as fuel for household lighting and cooking,由于字数的限制,可以去掉修饰词。combustible易燃的。)
转载请注明原文地址:https://kaotiyun.com/show/aUyK777K
本试题收录于:
A类竞赛(研究生)题库大学生英语竞赛(NECCS)分类
0
A类竞赛(研究生)
大学生英语竞赛(NECCS)
相关试题推荐
WhilebaseballisoftendescribedasthenationalsportoftheUnitedStatesofAmerica,itprobablydevelopedfromaneighteent
Researchhasshownthatcollegestudentscanlearnasmuch,ormore,frompeersastheydofrominstructorsandtextbooks.When
TherearetworeasonswhyIwantedtocometosouthernGermanytostudy.IwantedtobeatthecentreofEurope,withineasyrea
HowdidGregstartfire-walking?
Intheearly1950stheresearcherswhoproducedthefirstcladglassopticalfiberswerenotthinkingofusingthemforcommunic
—Icanneverdowellinmyfirstclassoftheday.Ithinkmybrainisstillasleep!—______—Maybeweshouldgojoggingbefore
AWorldWithoutTimeorNumberThePirahciareanisolatedAmazoniantribeofhunter—gathererswholivedeepintheBrazilian
Spaceandoceansarethenewworldwhichscientistsaretryingtoexplore.
Happilymyparentsalwayshada(n)______attitudetomystayingoutlateintheevening.
Bandscomeandgo.Somebecomefamous.Othersdon’t.Someenjoygreatwealth.Othersmakenothing.Butwhy?Sometimestheyjust
随机试题
不属于肿瘤一级预防的是()
有关放大摄影的叙述,错误的是
一般资料:李某,男性,26岁,无业。案例介绍:李某在母亲陪同下前来。其自小少言寡语,与人交往少,脾气暴躁。智力正常,孤独,生活懒散。一年前父亲病故时,李某还去网吧而且玩得兴致勃勃。最近几天经常笑。自述:和女友分手后,开始失眠,总感觉有人
________是中国第一部器乐合奏曲谱集,由清代蒙古族文人________所编。
婴幼儿由于眼球的生理特点,可能出现生理性远视,这一情况一般出现在3岁以前。()
1947年7月至9月,中国共产党召开了全国土地会议,制定和通过了《中国土地法大纲》,这是后期进行土地改革的政策依据。《中国土地法大纲》明确规定的土地政策和分配方案有
将Catalyst6500交换机的设备管理地址设置为203.29.166.9/24,缺省网关的IP地址为203.29.166.1,正确的配置语句是()
关系数据库管理系统能实现的专门关系运算包括()。
TheIdentificationofGoalsI.Introduction1)theimportanceofidentificationofgoalsforyourlifeandfuture2)twoquestions
U.S.ratesofdiseaseandsomecancers,【B1】______ofthebreast,areamongthehighestintheworld.Manyfactors【B2】______tocan
最新回复
(
0
)