ABSTRACT
After introducing terms and terminology of wastewater, sludge and excreta use, the chapter highlights their global drivers and significance using examples from different parts of the developing world. It is useful in the discussion to differentiate between unplanned use of wastewater resulting from poor sanitation, and planned use which tries to address matters such as economic or physical water scarcity. Both types of wastewater use can have significant socio-economic benefits but also institutional challenges and risks which require different management approaches and, ideally, different guidelines. This diversity makes the current WHO Guidelines, which try to be global in nature, complex to understand and apply. Whilst planned reuse will remain the norm in countries that can afford treatment, most countries in the developing world are likely to continue to use non-or only partially treated wastewater, for as long as sanitation and waste disposal are unable to keep pace with urban population growth. However, there are options to link urban faecal sludge and wastewater management with urban food demands or other forms of resource recovery that provide opportunities to safely close the nutrient and water loops.
