Page - 84 - in Clean Water Using Solar and Wind - Outside the Power Grid

84 Clean Water Using Solar and Wind: Outside the Power Grid number 6. Having available energy is just one of the key requirements. If individual households can be empowered, many of the sanitation problems in remote areas can be solved locally without the support of governments or other institutions. The main philosophy that should guide the wastewater treatment is that wastewater is not waste: it is a renewable and recoverable source of energy, nutrient resources and water. This should guide the development of used water treatment, considering: • Recovery and utilisation of energy content present in the water; • Recovery of nutrients; • Production of water for reuse. All three aspects can be satisfied with proven technology combined with renewable energy of realistic size. Decentralised used water treatment is described in 7.1. Various technologies are briefly explained in 7.2 and energy aspects to treat the water are summarised in 7.3. 7.1 MAIN SOURCES OF USED WATER Decentralised treatment plants are based on self-contained modular systems that provide efficient, scalable solutions to used water treatment problems of all sorts. To find out suitable technologies for decentralised water recovery treatment it is necessary to identify the various sources of water contamination. The traditional method of used water treatment has been to treat a single waste stream from a sewer system. A decentralised system can be designed in a different way with a separate treatment facility for each category of contaminated water. In this way we may look at urine, faeces and greywater as separate sources of used water instead of being components of one type of used water. The sources should be considered useful resources rather than waste. This will also help when possibilities for financing the treatment are considered (see Chapter 12). Depending on the source the used water can be treated differently. Here we consider three major sources from households: • Urine, • Greywater from washing, and • Blackwater from toilets. Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user