Addressing the lack of sanitation globally is a major global challenge with 700 million people still practicing open defecation. Circular Economy (CE) in the context of sanitation focuses on the whole sanitation chain which includes the provision of toilets, the collection of waste, treatment and transformation into sanitation-derived products including fertiliser, fuel and clean water. After a qualitative study from five case studies across India, covering different treatment technologies, waste-derived products, markets and contexts; this research identifies the main barriers and enablers for circular sanitation business models to succeed. A framework assessing the technical and social system changes required to enable circular sanitation models was derived from the case studies. Some of these changes can be achieved with increased enforcement, policies and subsidies for fertilisers, and integration of sanitation with other waste streams to increase its viability. Major changes such as the cultural norms around re-use, demographic shifts and soil depletion would be outside the scope of a single project, policy or planning initiative. The move to CE sanitation may still be desirable from a policy perspective but we argue that shifting to CE models should not be seen as a panacea that can solve the global sanitation crisis. Delivering the public good of safe sanitation services for all, whether circular or not, will continue to be a difficult task.

Faecal sludge reuse could promote responsible waste management and alleviate resource shortages. However, for this reuse to be carried out at scale, it needs to be financially viable. This paper reviews the financial values of resource recovery from 112 data points from 43 publications from academic and grey literature. The results found 65% of the existing literature is projected rather than being based on observed data from products in practice, with limited studies providing actual experiences of revenue in practice. Some of the estimates of the potential value were ten times those observed in data from operating businesses. Reasons for this include pricing of products against unrealistic competitors, for example, pricing briquettes against diesel fuel, or difficulties in marketing or regulation of products in practice. The most common form of reuse in practice is agricultural composting, which is also the lowest value product. Few cases were able to achieve more than $5/person/year from sludge reuse, therefore other drivers are needed to promote proper human waste disposal, including the health and dignity of citizens, but which are not easily monetised. Certification and recognition of product safety can improve the perception of value and products. Resource recovery has a limited role in the financial viability of providing Circular Economy sanitation in low-income countries. Instead, there is a need to focus on supportive policies and subsidies enabling the transition towards a Circular Economy supporting environmental quality, ecological health and human health.

Kenya has enshrined the right to sanitation in the 2010 constitution. Achieving this requires scaling up infrastructure and models of delivery beyond sewer networks that have previously been the focus. In Kenya, two enterprises, Sanergy and Sanivation, have been providing new forms of off‐grid services with container‐based sanitation (CBS). This paper uses a political economy analysis to understand the incentives, institutions and power dynamics that are enabling or constraining the potential for such off‐grid sanitation models. The paper outlines six core problems to be addressed in the pursuit of scaling up: fragmented governance; sustainability of CBS enterprise models; service delivery planning in informal settlements; personal power rather than institutions in decision‐making; vested local interests; and land tenure and political connection. It discusses how stakeholders might work collaboratively to progressively address or recognise these issues.

In‐field soil testing and soil mapping can contribute to addressing the challenge of poor soil fertility and limited fertilizer application across sub‐Saharan Africa. Semi‐quantitative colorimetric methods, such as paper test strips, are frequently employed in soil nutrient assessment across developing countries, especially in South‐East Asia. This research investigated the accuracy of nutrient‐sensitive paper strips and smartphone, which was re‐purposed to act as a reflectometer, to assess soil nitrate‐N, and different methods for mapping soil fertility to identify areas of land that are suitable for human waste‐derived fertilizers (HWDF) application. The study entailed testing soil samples across 42 different farms in Kenya and Ghana and compared it to laboratory results in‐country. It was found that paper strips were capable of assessing available nitrate‐N concentration present in the soil within ±20 kg ha ⁻¹ of the standard method for 86% of the farms. Paper strips were less effective in Ghana as they had been calibrated for a method that was not used by local laboratories. Paper strips were not effective for HWDF samples, where chemical interferences and concentration of different forms of nitrates were too high, resulting in overestimation of readings and thus negatively affecting any associated nutrient management advice. Soil mapping has the potential to use open‐source data to inform farmers through mobile technology. For soil mapping two methods were deployed which includes targeting organic matter deficient areas and stakeholder led mapping, with the latter shown to be more effective in identifying areas for HWDF application.

Re-using faecal sludge (FS) to generate value has the potential to contribute towards solving the issue of long term sanitation solutions in growing urban areas across sub-Saharan Africa; however, hitherto, no design tools have been available that are capable of simulating a system involving economic factors, complex social issues and environmental circumstances. We hypothesized that Agent-Based Modelling (ABM), when deployed with appropriate rigour, can provide such a tool. Extensive field work was carried out in a Malawian city, investigating the adoption of Skyloo above-ground composting toilets by households, and the operation of the municipal FS site. 65 semi-structured interviews and 148 household interviews, together with observations, were carried out to characterize these processes, with the data acquired being used to construct two separate ABMs. The Skyloo ABM was run for various scenarios of start-up capital for business and payback of loans against the toilet cost to households. The municipal FS Site ABM was run for different patterns of dumping fee and enforcement structure. The field work demonstrated that there is potential for further expansion of FS reuse, with a market for agricultural application. The Skyloo ABM identified the significance of start-up capital for a business installing the toilet technology; the municipal FS Site ABM showed that existing fees, fines and regulatory structure were insufficient to reduce illegal dumping of FS to any useful degree, but that a monthly permit system would provide enhanced revenue to the city council compared with per-visit charging of disposal companies at the municipal FS site. Whilst each ABM ideally requires some additional data before full application, we have, for the first time, shown that ABM provides a basis for the simulation-based design of FS management systems, including complex social, economic and environmental factors.