Using sunlight to clean waste water

Feb 22^nd, 2010 | From The Economist online

 

Ultraviolet light has long been used in water-treatment plants to help with disinfection. As long as the water is clear enough not to absorb the rays, exposing it to a discharge lamp will destroy the DNA of viruses, bacteria and protozoa
that could otherwise cause illness when swallowed. The ultraviolet that exists
in sunshine can also be used this way. A rough and ready method for sanitising water, for example, is to pour some into a clear plastic bottle, aerate it by shaking and then place it in the sun for six hours. Now a group of German companies including KACO, a solar-power firm, have gone one better. They have developed an industrial-scale solar-driven purification system that removes not only bugs but also chemical pollutants.

The first of their devices has been built as demonstrative project
at the German Aerospace Centrein Lampoldshausen. This organisation, which
was among the group of developers, wanted to clean the water that it uses to cool its experimental engines. This cooling water inevitably gets contaminated both with rocket fuel and with substances produced by that fuel’s combustion.

The trick the researchers use to boost the cleansing action of ultraviolet
is to add a light-activated catalyst to the effluent. They have come up with two sorts, one for heavily polluted water and one for water that is only lightly polluted.

For water containing serious industrial contaminants, like that
at Lampoldshausen, they use iron sulphate as the catalyst and add a small amount of hydrogen peroxide and sulphuric acid to assist the process. Thus treated, the water is pumped through arrays of transparent glass tubes in a 49 metre-long solar reactor. In a complex series of reactions, one of which is promoted by ultraviolet light, the iron reacts with both the hydrogen peroxide and some of the water itself to produce powerful oxidising agents known as hydroxyl radicals. These destroy the polluting molecules. Once the water has been cleaned, the acid is neutralised, causing the iron to become insoluble. It precipitates out as iron oxide and can then be recovered and recycled, leaving water pure enough to discharge into a river.

For less heavily polluted water, similar equipment is used, except that
the glass tubes are coated with titanium dioxide. This substance is
a semiconductor, meaning that when electrons (which are negatively charged)
are knocked free from its crystal structure, the result is a positively charged “hole” that can move around inside the crystal. This hole is also a powerful oxidiser.
One of the ways a hole can be created is for the electron to be displaced by ultraviolet light. A titanium-dioxide system, which is still in development, could purify water
to the point where it was suitable not merely for discharge, but for drinking.

The iron-sulphate system at Lampoldshausen, meanwhile, is capable
of treating 4,500 litres of waste water in an hour or two. It would be even more efficient in sunnier climes, and these are expected to become the main market
for the process, which KACO has started to produce under the brand name RayWOx.

The German Aerospace Centre reckons RayWOx will be good at removing certain pollutants that are particularly hard to get rid of at the moment, notably antibiotics, X-ray contrast media and hormones. KACO, meanwhile, says
it will be able to supply the system complete with photovoltaic cells to power both the control electronics and the pumps, making it not just cheap to operate, but also ideologically sound – a green, mean, cleaning machine, powered entirely by the sun.

 

Text E

Geothermal energy

 

Another alternative energy resource is the heat from the Earth’s interior.
The surface expression of this energy is manifested in volcanoes, fumaroles, steam geysers, hot springs and boiling mud pools. Global heat-flow maps constructed from geophysical data show that the zones of highest heat flow occur along
the active plate boundaries. There is, in effect, a close association between geothermal energy sources and volcanically active regions.

A variety of applications have been developed for geothermal energy.
For example, public buildings, residential dwellings and greenhouses in such areas as Reykjavík, Ice., are heated with water pumped from hot springs and geothermal wells. Hot water from such sources is also used for heating soil to increase crop production (e.g., in Oregon) and for seasoning lumber (e.g., in parts of New Zealand). The most significant application of geothermal energy, however, is the generation of electricity. The first geothermal power station began operation in Larderello, Italy in the early 1900s. Since then similar facilities have been built in various countries, including Iceland, Japan, Mexico, New Zealand, Turkey and the United States. In most cases turbines are driven with steam separated from superheated water tapped from underground geothermal reservoirs and geysers.

 

Words and expressions:

alternative energy resource – альтернативный источник энергии

volcanoes – вулканы

steam geyser – паровой гейзер

hot springs – горячие источники

boiling mud pool – кипящая глина

global heat-flow map – глобальная карта теплового потока

geothermal energy source – геотермический источник энергии

volcanically active region – вулканически активная область

residential dwellings – жилье

greenhouse – парник

crop production – производство сельхозпродуктов

significant application – важное применение

generation of electricity – выработка электричества

 

 

Exercise 1

Ответьте на следующие вопросы:

1. Is geothermal energy extracted from the Earth’s interior?

2. How did the surface expression of geothermal energy manifest?

3. How are global heat-flow maps constructed?

4. Is there a close association between geothermal energy sources
and volcanically active regions?

5. What applications have been developed for geothermal energy?

6. Is geothermal energy used in public buildings, residential dwellings
and greenhouses?

7. What is the most significant application of geothermal energy?

8. When did the first geothermal power station begin operation?

9. What countries are famous in using the geothermal energy?

 

Exercise 2

Заполните пропуски недостающими по смыслу словами, используя текст:

1. The surface expression of geothermal energy is manifested in …, …, ….

2. A variety of … have been developed for geothermal energy.

3. Hot water from such sources is also used for … soil to increase crop production.

4. The first … power station began operation in Larderello.

5. Geothermal power stations have been … in various countries.

6. At such stations … are driven with steam separated from superheated water.

 

Exercise 3

Соответствуют ли данные предложения содержанию текста?

1. Another alternative energy resource is the heat from the Earth’s interior.

2. Global heat-flow maps constructed from geophysical data show that
the zones of highest heat flow occur along the banks of the rivers.

3. There is no any association between geothermal energy sources
and volcanically active regions.

4. A very few applications have been developed for geothermal energy.

5. Geothermal energy is used for heating public buildings, residential dwellings and greenhouses.

6. The most significant application of geothermal energy is the generation
of electricity.

7. The first geothermal power station began operation in Canada in the early 1990s.

8. Since then similar facilities have been built in Russia and Poland.

Exercise 4

Используя текст, составьте высказывания с данными словами
и выражениями:

alternate energy resource; Earth’s interior; surface expression; hot springs; global heat-flow maps; geophysical data; active plate boundaries; volcanically active regions; a variety of applications; public buildings; residential dwellings; water pumped from; hot springs and geothermal wells; to increase crop production; application of geothermal energy; geothermal power station.

 

Exercise 5

Кратко передайте содержание каждого абзаца.

 

Exercise 6

Выделите пять основных идей текста.

 

Exercise 7

Составьте предложения, используя данные выражения:

energy resource; geophysical data; zones of highest heat flow;
close association; variety of applications; hot water from such sources; significant application; generation of electricity; to begin operation; similar facilities; turbines are driven; steam separated; underground geothermal reservoirs.

 

Exercise 8

Переведите на русский язык следующие предложения:

1. Geothermal energy is the heat from the Earth’s interior.

2. Geothermal energy is manifested in volcanoes, steam geysers, hot springs and boiling mud pools.

3. Scientists state that there is a close association between geothermal energy sources and volcanically active regions.

4. Geothermal energy is applied for heating public buildings, residential dwellings and greenhouses.

5. Public buildings, residential dwellings, and greenhouses are heated
with water pumped from hot springs and geothermal wells.

6. In Oregon hot water from the hot springs and geothermal wells is used
for heating soil to increase crop production.

7. The most significant application of geothermal energy is the generation
of electricity.

8. The first geothermal power station began operation in Italy, in the early 1900s.

9. Nowadays geothermal power stations operate in various countries, including Iceland, Japan, Mexico, New Zealand, Turkey and the United States.

Exercise 9

Переведите на английский язык:

1. Одним из важных источников энергии на сегодняшний день является геотермическая энергия.

2. На поверхности Земли геотермическая энергия выражена в вулканах и паровых гейзерах.

3. Карты теплового потока в земной коре составляются учеными геофизиками.

4. Существует тесная и непосредственная связь между геотермическими источниками энергии и вулканически активными регионами.

5. Области применения геотермической энергии очень широки.

6. Во многих европейских странах геотермической энергией отапливаются общественные здания, жилье и оранжереи.

7. Геотермические источники также используются для нагрева почвы
в целях увеличения урожайности.

8. Самой главной областью применения геотермической энергии является выработка электроэнергии.

9. Первая геотермическая электростанция была построена в 1900 году
в Италии.

10. В настоящее время геотермические электростанции успешно работают во многих странах мира.

 

Exercise 10

Текст для самостоятельного перевода.

 

Lexington

The politics of disaster