12.2 Reading


linking ideas • labelling a diagram • making and writing up notes from a text A Discuss the following questions.


1 What factors should be considered when building a desalination plant?


2 What are the main costs involved?


3 What are the environmental impacts of desalination?


B Study the words in box a.


1 Match words in the left and right columns to make seven compounds.


2 Which compounds have adjective + noun?


3 Which word has the stronger stress in these phrases?


C Read the text on the right. 1 Complete the text using the phrases from box a.


2 How do you expect the text to continue?


D Survey the text on the opposite page. 1 How is the text organized?


2 For each of the four stages, write a question you would like the text to answer.


E Read the text. 1 Were your questions answered?


2 Label the diagram on page 107 and use arrows to show the flow of water.


F Look at the underlined words in the text. What do they refer back to?


G Find synonyms for the blue words and phrases.


H Study the highlighted clauses in the text. 1 Rewrite them using passive verbs. 2 Find other examples of passives.


3 Why is the passive form commonly used in this type of writing?


I Study the sentences on the right. Each sentence completes one of the four sections in the text.


Decide on the best location for each sentence. Explain your decisions.


J Read the text about thermal desalination on page 108.


1 Make notes from both texts, comparing the two processes. Copy the table for your notes.


2 Write a summary of the key differences for a water company. Finish with your recommendation.


96


a


capital global power


regional reverse


desalination developments factors osmosis contexts


technological costs membrane


generation Desalination technologies: Introduction


Among the number of desalination technologies available, the two most common large-scale commercial processes are reverse osmosis (


) and thermal desalination


(distillation). The choice of method depends largely on


, including economic


considerations and types of input water. For example, thermal desalination has traditionally dominated water production in the Middle East, not only because local energy is cheap, but also because the heat and high salinity of the seawater has been more suited to distillation. The region also makes use of cogeneration by integrating


and thermal desalination, thereby


increasing efficiency and reducing costs. In other , such as the US, Europe,


Australia and elsewhere, where oil or other fossil fuels are more expensive,


has


been more common. Today, as reverse osmosis decrease due to


it is now becoming the most economical and effective method of large-scale desalting, and the preferred choice for new plants worldwide.


A B


The three common methods of disinfection are ultraviolet radiation, ozonation and chlorination.


Desalination plants also produce an amount of solid waste that ends up in landfill, including discarded pre-treatment filters and solid particles filtered out during pre-treatment.


C D


Backwashing is a method of cleaning pipes by reversing the flow of liquid.


Current research into improving the permeability and performance of membranes focuses on nanostructures and nanomaterials.


Reverse osmosis • less energy required Thermal desalination


• needs large amts. of energy to heat water


of ,


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