Mô tả câu hỏi

Read the text and do the activities that follow.

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 plagues by a lack of adequate sanitation. Improper waste disposal spreads disease, contaminates water sources and provides breeding ground for disease-carrying insects.

The problem 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: 38,000 are reported in rural area 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 percent of India’s plants, for instance, were built during the energy and fertilizer crisis of 1975-76 – 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 form 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 manorial 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.

According to the reading passage, are the statements T (True) or F (False)?
1. ...... Biogas is the answer for the lack of cheap, convenient and reliable fuel.

2. ...... The production of biogas by fermentation of animals and vegetables wastes is a technology used in developed countries.

3. ......[F] Family –sized biogas plants first came into widespread used in India in the 1940s.

4. ...... There are less and less biogas plants in the world nowadays.

5. ...... Biogas is for domestic use.

6. ...... The system is economically sound, in addition to other benefits such as a cleaner, healthier environment.