One-third of the global population relies on non-sewered sanitation. In urban areas of low-and-middle income countries, treatment of faecal sludge is often insufficient. On-site sanitation technologies can provide sustainable and more affordable sanitation solutions for urban areas, but only if functioning faecal sludge management is in place. As a first step for treatment, faecal sludge is dewatered, resulting in a solid stream and liquid stream. There are many existing technologies to treat the solid fraction. However, treatment technologies for the liquid are often insufficient and land-intensive. This liquid after dewatering of faecal sludge is called ‘supernatant’. The reason why treatment of this supernatant is difficult, is because the composition is prone to variability.

In conventional sewer-based wastewater treatment, attached growth processes have proven to be robust to influent variability. Those technologies do not take a lot of space, which is an advantage in urban areas. Attached growth processes are aerobic treatment processes in which the biomass responsible for treatment is attached to some type of medium. This research is a proof of concept whether an attached growth system, in this case an MBBR process, could be an alternative for existing supernatant treatment technologies in non-sewered sanitation. A 5000 people urban community-scale scenario is considered, covering variability in influent composition and intermittency in faecal sludge supply.

To prove this concept, there is looked whether COD and N removals can be achieved to certain discharge standards.
First there is assessed whether the MBBR is able to run on one type of supernatant. After this, the variability in influent composition regarding COD/N ratio, salt ratio, and pH is tested by spiking the baseline supernatant. Intermittency in influent supply to the reactor is also tested. After these separate experiments, a realistic scenario is tested with supernatants from different types of sources, and intermittent supply over the weekend.

As a conclusion, the concept of using an MBBR for treatment of supernatant after dewatering of faecal sludge is proven for a community-scale scenario of 5000 people, and further research has to determine new outcomes like the possibility of pathogen reduction and phosphorous removal. After this, field tests need to determine the actual feasibility full-scale in non-sewered sanitation setting.
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The Good Roll, a company based in Amsterdam, produces 100% tree-friendly and sustainable toilet paper. Half of their profit goes to their foundation, building toilet facilities all over Ghana, called The Good Toilet. With the concept of The Good Toilet, they want to provide access to sanitation for all Ghanaians, with an economically viable facility, and with the least environmental impact. They want to build toilets all over Ghana, going from school projects to household and community level toilets. The Good Toilet is a whole community centre with toilets, showers, hand washing stations, and a store. There are already 285 toilets built in a first design. This current design is examined in this thesis, as after a field trip in November 2021 some non-foreseen problems came to light. During this field visit samples of the used borehole water were taken and brought back to The Netherlands. The current treatment system, a solid liquid separator and activated coal filter was checked as well. The water used in the facilities seemed to be contaminated with E.Coli, and the effluent stream was entirely clogged. This raised the first research question, namely how the current system can be free from an environmental and health hazard. Secondly it was examined what a new design for the second version of The Good Toilet could be. For this interviews were conducted with people from the emergency context, professors, and people with experience building toilets in low-income countries. Next to this, a literature research was performed and case studies were examined. With this information and estimated guesses a muti-criteria decision matrix within a framework of requirements was created, deciding upon suitable treatment choices for The Good Toilet 2. Next to technical considerations, the social aspect of building toilets in low-income countries was looked at as well, as this could increase the usage of The Good Toilet and therefore decrease open defecation practices in Ghana. For this, inspiration was taken from the SaniTweaks document of Oxfamwash. Combining the technical and social aspects of building toilets, an advice could be drawn up to The Good Roll for their projects in the future ... Read more