More than 80 per cent of wastewater from human activities is discharged into the rivers or sea without any pollution removal, and the Sustainable Development Goals (SDGs) aim to halve this proportion and increase recycling and reuse globally by 2030. Treatment plants in Sub-Saharan Africa often fail due to lack of operating funds, poor regulation and poor design that does not take into account human factors. The failure of treatment plants can also be put down partly to the funding structures for management, which are often dependent on the disposal tariffs charged. Without sufficient regulation and enforcement, which is often lacking in Sub-Saharan Africa, this often leads to illegal disposal of faecal sludge. Due to the nutrient content and energy potential of wastewater, there is increasing focus on reuse of faecal sludge in ways that can contribute funds for maintenance and incentivise good management of treatment facilities. This research investigates potential designs for the re-use of faecal sludge in small cities in Sub-Saharan Africa to ensure proper treatment. Conducting two case studies using qualitative and quantitative methods, the research looks at the potential for re-use to be scaled up in Sunyani, Ghana and Mzuzu, Malawi, and whether different designs can ensure good management. Building upon the research investigation into how previous designs have failed in case studies, the research also investigates the use of agent-based modelling (ABM) as a modelling approach to explore social and technical aspects of sanitation systems to predict how different designs and management approaches can work. In Sunyani, biogas was the most acceptable option to customers whilst also providing a good business model to fund faecal sludge treatment, either as a decentralised system at public toilets where the fresh sludge is better for biogas production, or centrally at the existing disposal site. The success of biogas as a model that can fund maintenance and ensure good management would depend on the faecal sludge quality of public toilet sludge in the city and the investment level required and how any operating approach would work between the government and private sector. In Mzuzu, two main approaches to faecal sludge re-use exist currently: the implementation of Skyloos as above ground household toilets which provide compost, and a central disposal site from which compost is illegally harvested. At disposal, farmers remove sludge from the ponds and apply it untreated directly onto agricultural land. At times, private sector emptying services do not use the ponds, but also apply untreated sludge to agricultural land. Skyloos were found to have varying levels of success from different Non- Governmental Organisation (NGO) projects, with key sustainability issues being the availability of financing mechanisms, management between landlords and tenants and the trust of and engagement with implementing organisations. Existing approaches to waste management and re-use were found to be inaccessible and not working when implemented for the poorest and people with disabilities. Adopting re-use of faecal sludge in agriculture in Malawi would require improved marketing of sanitation options, financing options for households to incentivize adopting the technology, not targeting to poorest households and people with disabilities, and an improved management model for the treatment site to ensure safe disposal and production of compost. Looking at ABM as a way of modelling faecal sludge treatment systems in Sub- Saharan Africa, two models of different approaches in Mzuzu were developed to look at scaling up Skyloo toilets and managing the treatment plant. Both models demonstrate the potential of ABM to incorporate social and technical aspects into predicting the performance of different designs and approaches. The success and use of modelling depends on the quality of data that can be collected before implementing system approaches. Overall the thesis presents different models of treatment and re-use that can work and contribute to operating and maintenance of systems. It is unlikely that any design system will be so profitable that the treatment and re-use of sludge will be able to ensure good management without regulation, so the success of designs depends on relationships between the government and private sector and households in small cities.

Proefschrift--Delft. / "Stellingen": 5 p. laid in. Includes bibliographical references.

Aggravated by rapid population growth, urbanization, and industrialization and most recently by climate change events, the availability of water especially in the third world is reaching critical proportions.  This is aggravated by the non treatment of wastewater (sewage) and discharged of untreated wastewater into water bodies. The study focused on identifying and reviewing four wastewater treatment methods from a sustainability perspective; waste stabilization pond, constructed wetland, up-flow anaerobic sludge blanket reactor and sedimentation/thickening tank systems suitable for the Limbe Urban Municipality (LUM) of Cameroon in Central West Africa with an estimated population of 120, 000 inhabitants and experiencing 4.7 per cent annual growth rate. The attractiveness of these four methods stems from their apparent energy efficiency, simplicity, robustness, low cost effectiveness in situations where as in the LUM, there are huge tracts of available land, warm temperatures, and their capacity to promote effluent re-use opportunities for various sectors. Issues of sustainability of the water supply and wastewater treatment systems, untreated sewage, and their contribution to escalating environmental and public health impacts in LUM (Cameroon) were critically evaluated and discussed with the aid of Kärrman (2000) framework approach that employs different sets of sustainability criteria (Environmental, Health and Hygiene, and Functional), sub-criteria and indicators. Results obtained reveal that water and wastewater treatment systems in LUM do not operate or conforms to sustainability perspectives. Inhabitants do not still have access to clean drinking water (an approximate 45 per cent) especially in the dry periods of the year, low sanitation coverage (with the tradition of sewage treatment in septic tanks and pit latrines), rising yearly public health impacts associated with water-borne (cholera, dysentery, malaria, typhoid fever and diarrhea) infections and 6 deaths reported in LUM. These leading problems are directly or indirectly linked to consumption of contaminated water or foods in different communities such as Mile II, Isokolo, Bonadikombo (Mile four) etc, and New Town areas and flood prone zones in the Limbe urban municipality.

This research is about the social/spatial management of water in an urban setting. The water utility of Piacenza, Italy, and specifically, the organization of the now extinct canal system, was investigated for the period between 1545 and 1736. Through analysis of the administration of the canal system and the water utility this thesis constructs an aspect of the political ecology of Piacenza. Political ecology as a discipline lies at the intersection of the environmental context, land use, spatial design, demographics and social relationships. The study looked at how the city organized itself to manage urban water and sanitation delivery, the methods used to communicate with the users, the actions taken to keep the system in good repair, the responses to crises, and the limitations of the social organization and technological capabilities. The archival documents contained within the Congregazione sopra l’ornato (CSO), the municipal committee charged with management of the canals, form the core of the research. Analysis revealed a finely-tuned social system that involved noble oversight, the use of expert engineers, public/private partnerships for maintenance of the canals with millers and consorti as key people, and an attempt to control cheating with fines and penalties.