Page - 61 - in Clean Water Using Solar and Wind - Outside the Power Grid

© 2019 The Author. This is an Open Access book chapter distributed under the terms of the Creative Commons Attribution Licence (CC BY-NC-ND 4.0), which permits copying and redistribution for non-commercial purposes with no derivatives, provided the original work is properly cited (https://creativecommons.org/licenses/by-nc-nd/4.0/). This does not affect the rights licensed or assigned from any third party in this book. The chapter is from the book Clean Water Using Solar and Wind: Outside the Power Grid, Gustaf Olsson (Author). doi: 10.2166/9781780409443_0061 Chapter 5 Water treatment “We never know the worth of water until the well is dry.” Thomas Fuller, English churchman and historian (1608–1661). The gap between available water resources and our domestic, municipal and industrial needs is becoming wider. Key causes are climate change and population growth. The number of people living in regions affected by severe water stress is expected to increase by a billion to almost four billion in the next two decades. The most severely affected regions will be North Africa, the Middle East, northern China, southern India, Pakistan and certain parts of the United States and Mexico. At the same time almost 40% of the global population live less than 100 km from the sea and 60% of the world’s biggest cities in coastal areas do not have access to fresh water. The available groundwater or surface water in remote regions may have a low quality and the contaminants need to be eliminated or reduced. The water must be cleaned to an acceptable quality, which depends on the final use. Naturally, drinking water needs to satisfy much higher quality standards than water for cleaning or for irrigation. In 5.1 an overview of water treatment technologies is presented. Filtering is often the first step in water purification, Section 5.2. Desalination is a Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user