Philosophical, ecological and technical challenges for expanding ecological sanitation into urban areas.

Ecological sanitation seems often to be taken to mean no more than an alternative toilet, whereas it should be understood more broadly as embodying a closed-loop approach to the management of human excreta. In the next 25 years the urban population of Africa and Asia is expected to double. By facilitating the revival of urban agriculture and avoiding the adverse environmental impacts of conventional treatment strategies, ecological sanitation can play a major role in providing food security and public health in a sustainable future.