Seite - 63 - in Clean Water Using Solar and Wind - Outside the Power Grid

Water treatment 63 eliminating the salt. Another increasing water supply problem is the invasion of seawater into groundwater. Sometimes the groundwater resources have been exhausted. In other cases, the rising sea level caused by climate change will intensify the problem. Table 5.1 indicates typical salinity for various water qualities. Table 5.1 Salinity for different kinds of waters. Salinity (ppm = mg/l) Seawater 35,000 Highly saline water 10,000–35,000 Brackish water 1,000–10,000 Fresh water <1,000 5.1.3 Contaminated water It is crucial to make drinking water safe to drink. Many groundwater or surface water sources in remote areas have highly contaminated water, not only pollution from organic carbon (COD) or nutrients (ammonia and phosphorus) but also pathogenic bacteria, viruses, protozoa and worms. Many sources are highly contaminated due to the presence of harmful metals like fluoride and arsenic, which cause serious health hazards. Obviously, unsafe contaminants must be eliminated. The surface water sources are frequently used as dumping grounds and at the edges of the water bodies there is often defecation, which results in bacteriological contamination. This is a challenge not only to agricultural production and rural livelihoods, but also to food safety. To remove contaminants requires energy. Biological treatment to remove COD typically requires a certain energy per kg of COD. Disinfection of water can be done in several ways. One principal way is disinfection via UV light. Another is via filters of various sizes. Both of them require electric energy to provide the UV light or to produce a pressure to operate membrane filters. Treating contaminated water requires more energy. Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user