Drinking Water Treatment Technology—Comparative Analysis
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Water treatment technologies have evolved over the past few centuries to protect public health from pathogens and chemicals. As more than a billion people on this earth have no access to potable water that is free of pathogens, technologies that are cost effective and suitable for developing countries must be considered. Sustainable operation of these treatment processes taking into consideration locally available materials and ease of maintenance need to be considered. In this chapter, we consider natural filtration for communities of various sizes. In natural filtration, slow-sand filtration and riverbank filtration are considered. Slow-sand filtration is suitable for small to medium size communities, whereas riverbank filtration can be suitable for small to very large communities depending on site and river conditions. Membrane filtration is another technology that can have application to individual households to moderately large communities. Both pressurized and gravity-fed systems are considered. For the developing regions of the world, small membrane systems have most applications. Solar distillation is a low-cost technology for sunny regions of the world. Particularly, it has the most application in tropical and semitropical desert regions. It can use low quality brackish water or groundwater for producing potable water. These systems can solely operate with solar energy. The scale of application is for individual households to very small communities. Solar pasteurization, like solar distillation depends on solar energy for purifying small quantities of water for individual or family use. It is most suitable for remote, sunny, high mountain regions such as the Andean mountains, central Africa or the Upper Himalayas where electricity is not available. Also, reliance on firewood is not feasible due to barren landscape in many of these regions. Also, case studies of natural (riverbank and lakebank) filtration, membrane filtration, solar distillation, and solar pasteurization are presented.