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
2016-01-10
62
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 ma-nurial 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.
The production of biogas by fermentation of animal and vegetable wastes is a technology that has been largely developed and used in the【R1】______countries. Only very recently have scientists in the industrialized nations begun to show an interest—presumably because of the "energy【R2】______".
Family-sized-biogas【R3】______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【R4】______One Chinese study has shown that digestion of animal【R5】______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.
【R4】
选项
答案
Sanitation/environmental hygiene
解析
(第三段开头,Rural areas of developing countries are also plagued by a lack of adequate sanitation,发展中国家的农村地区的卫生状况普遍不佳,联系上下文可知,沼气的使用可以改善这种不佳,即提高卫生水平。)
转载请注明原文地址:https://kaotiyun.com/show/9VyK777K
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
Diamondshavelittle______valueandtheirpricedependsalmostentirelyontheirscarcity.
Ourmodemcivilizationmustnotbethoughtofas______inashortperiodoftime.
Thedemandforenergyiscertaintoincrease...asaneverlargerpopulationstrivestoimproveitsstandardofliving.Petroleum
Youngpeopleareinevitablyattheleadingedgeofchangeandinnovationandthetravelindustryisnoexception.Youngpeopleth
TheMid-AutumnFestivalisanimportantfestivalinsomeAsiancountries.Becausethedateofthisfestivalissetaccordingto
Manystudentsfindtheexperienceofattendinguniversitylecturestobeaconfusingandfrustratingexperience.Thelecturerspe
WhichofthefollowingisthemostfamousworkoftheAmericannovelistF.ScottFitzgerald?
Accordingtousageandconventionswhichareatlastbeingquestionedbuthavebynomeansbeenovercome,thesocialpresenceof
Hewasafunnylookingmanwithacheerfulface,good-naturedandagreattalker.Hewasdescribedbyhisstudent,thegreatphi
Lowlevelsofliteracyandnumeracyhaveadamagingimpactonalmosteveryaspectofadultlife,accordingtoasurveypublished
随机试题
Testing:IsittheOnlyWaytoEvaluateStudents?Abouttenpercentof【C1】________(spend)onprimaryandsecondaryeducatio
鉴别慢性淋巴细胞白血病与毛细胞白血病首选的细胞化学染色是
患者,男,62岁。1765、24567,4765、367缺失,可摘屑部义齿初戴后1个月,咀嚼时常咬颊黏膜,下颌舌侧第一磨牙至磨牙后垫区压痛,来院复诊。压痛区检查时应注意
甲将所拥有的房屋出售给乙。该房屋正由丙租用,乙同意丙按原租赁合同继续租用,那么甲、乙双方进行房屋所有权转移登记时,应缴纳的契税由( )承担。
某两环管网如图1—15所示,经计算闭合差不满足精度要求,校正流量为△qⅠ=3.0L/s,△qⅡ=一2.0L/s,则经过校正流量的调整,管段2—5的流量应从20.0L/s调整为()。
向参与网下配售的询价对象配售时,询价对象应当承诺获得本次网下配售的股票持有期限不能少于3个月,持有期是自本次公开发行的股票上市之日起计算。()
早在20世纪20年代,梁启超先生就已意识到国人对“科学”存在失之偏颇的理解。他指出:“那些绝对的鄙厌科学的人且不必责备,就是相对的尊重科学的人,还十个有九个不了解科学的性质。他们只知道科学研究所产生的结果,而不知道科学本身的价值……我们若不拿科学精神去研究
()不属于电子邮件协议。
扩展名为mnx的文件是
Mymothercan’tget__________becauseshehasrheumatism(风湿病).
最新回复
(
0
)