Generation and evaluation of sanitation options for urban planning. Systematic consideration of technology innovations and sustainability criteria
Motivation. It is particularly challenging to reach SDG 6.2, access to sanitation for all, in urban areas of developing countries, where most of the current global population growth is taking place. Traditionally, urban sanitation planning is based on top-down, one-size-fits-all approaches. This has often led to inappropriate technology choices and failing projects worldwide, particularly in urban areas of developing countries. Conventional centralized sanitation is often inappropriate in these areas because it depends on capital-intensive sewer networks, large quantities of water, stable institutions with adequate capacities, and long planning horizons. Increasing investments in the development of novel technologies (e.g. urine separation) and system configurations (e.g. container-based sanitation) have been the result. These innovations can be more appropriate (independent from sewers, water and energy) and sustainable (adaptable to changing environmental and socio-demographic conditions, and saving/recovering water, nutrients, and energy).
Research need. While novel technologies and system configurations potentially enhance sustainability, they also increase planning complexity. Structured decision-making (SDM) has been found to assist the planning process, by combining decision analysis with engineering, and balancing opposing interests in a facilitated framework that embraces all relevant steps. To support the application of SDM, several frameworks were developed over the past decades (e.g. Community-led Urban Environmental Sanitation, CLUES, or Sanitation21). Yet, they are rarely used in practice. Recent research focuses on developing tools that operationalize the different planning steps, but these tend to prioritize methods for understanding the problems (e.g. Shit Flow Diagrams, SFDs), or for the selection of preferred options (e.g. multi-criteria decision analysis), assuming that the options to choose from are given. However, the currently available technologies result in an unmanageable number of possible system configurations (>100’000). The present technological development requires methods that generate a manageable number of locally appropriate sanitation decision options and that are systematic and can deal with the growing portfolio of technologies and sustainability criteria. Moreover, there is a lack of generic methods to quantify the performance of novel sanitation system configurations at the scale of an entire city. The identification of options and their comparison is further hampered by the lack of knowledge or data, particularly for novel options.
Research objectives. The objective of this thesis is to develop systematic and generic methods to identify locally appropriate sanitation system options and to evaluate their performance in terms of resource efficiency. The aim is to use these results as an input into the decision-making process. The methods shall: (i) consider entire sanitation systems from the toilet to reuse or disposal; (ii) be applicable to a large and diverse range of technologies and system configurations; and (iii) integrate criteria from all sustainability dimensions. Given the context of expanding urban areas and the focus on novel technologies, the methods should also be able to deal with uncertainties. The thesis covers three specific objectives: (I) methods for sanitation system options generation; (II) methods to quantify resource recovery potentials of entire systems as a performance indicator for the evaluation of their sustainability; and (III) a procedure for the integration of the methods in SDM and their practical application. The third objective also includes the analysis of the implementation of practical applications in Nepal, Ethiopia, South Africa, and Peru. [...]