ABSTRACT
The reuse or utilization of wastewater, faecal sludge and its embodied resources is widely acknowledged in the field of sanitation as a key component of complete sanitation. Reuse, for agriculture and other applications, is conventionally considered a means of mitigating water shortage or abating water pollution. We contend that reuse-oriented sanitation can also be leveraged to improve the long-term efficacy of a treatment scheme by providing tangible and quantifiable incentives for sound operation and maintenance that exceed those associated with running a disposal facility. The standards that need to be met for agricultural reuse are different from those required for discharge to the aquatic environment. This difference requires a change in the design philosophy and can lead to cost savings in the type of treatment process, the energy demand and the skills needed for operation. So, rather than a more complex system, wastewater treatment designed for agricultural reuse can result in a more appropriate plant for developing countries striving to enhance access to improved sanitation.
To facilitate a culture of designing site-specific and reuse-oriented systems from the outset of the planning process, this chapter introduces a five-step planning tool, Design for Service (DFS). DFS defines wastewater as a resource and choices about its reuse inform the infrastructure design including site and technology selection, and plant scale. We highlight reuse schemes at various stages of implementation in South Africa to exemplify difficulties faced in the absence of accessible planning frameworks. To demonstrate how DFS can be used for rehabilitating schemes that have fallen into disrepair and for the design of new reuse-oriented sanitation systems, we describe projects that are currently underway in Ghana and China, respectively.
