5.14.2 Reverse osmosis

This technique, explained in Section 3.8.1, is rapidly becoming a major means of desalination, with research producing membranes with lower operating pressures (and hence lower operating costs). Originally a pressure of 14 × 106 Pa was needed to separate pure water from sea water but with newer membranes only half this pressure is required. Reverse osmosis membranes operate at ambient temperature, in contrast to multistage flash distillation, and this lower temperature minimises s
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Introduction

This unit is from our archive and it is an adapted extract from Environmental Control and Public Health (T210) which is no longer in presentation. If you wish to study formally at The Open University, you may wish to explore the courses we offer in this curriculum area.

With
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3.3.3 Reassembling the parts

As the wreckage was pulled from the river it was examined and identified, and any failures of the metal components were recognised and tagged. This was a mammoth task, given that virtually the whole bridge had fallen into the water, including all the road decks, trusses, chains and hangers, eye bars and the two towers. The parts were then reassembled and all the failed or fractured components photographed and catalogued. Over 90 per cent of the bridge components were collected together and re
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2.6 Corrosion in stressed products – stress corrosion cracking (SCC)

If a stress exists in a product exposed to a corrosive environment, the rate of corrosion can then increase and be extremely localised, such as at the tip of a growing crack. Furthermore, some specific chemicals are so aggressive that corrosion will occur at relatively low stress levels, such as those created during manufacture, for example. The residual stress in a component can then be enough to trigger crack growth and failure.


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4.3 Voice and accompaniment

One thing that is clear from the Lieder we have already considered is that Schubert's writing for the piano is a crucial element of his skill as a songwriter. Sometimes, and throughout his career, he wrote very simple accompaniments, as in ‘Heidenröslein’ – the approach favoured by Goethe and many other writers of the time, who considered that the German Lied should not overload the poem with too much elaboration. Schubert's later version of the ‘Harper's Song’ is more complex, wit
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2.2.1 The recordings

Click 'play' to listen to the interview with Sorley MacLean (Part 1, 7 minutes).

Download this audio clip.