A review of the financial value of faecal sludge reuse in low-income countries

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

Designing sustainable faecal sludge treatment systems for small cities in Sub-Saharan Africa

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

Agent-based modelling for simulation-based design of sustainable faecal sludge management systems

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

Agent-based modelling for simulation-based design of sustainable faecal sludge management systems

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

When faecal sludge reuse doesn’t work: a look at access for the poorest and people with disabilities in urban Malawi

Reusing faecal sludge to generate value has the potential to contribute towards solving the issue of long term sanitation solutions in cities across Sub-Saharan Africa. This research was conducted to evaluate the potential for faecal sludge reuse in Malawi, and the difficulties and challenges to existing attempts at reuse in a city. We conducted 65 semi-structured interviews in a city of Malawi. The results show that two main approaches 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. Both existing approaches to faecal sludge management and reuse were found to be inaccessible and not working when implemented for the poorest and people with disabilities

When faecal sludge reuse doesn’t work: a look at access for the poorest and people with disabilities in urban Malawi

Reusing faecal sludge to generate value has the potential to contribute towards solving the issue of long term sanitation solutions in cities across Sub-Saharan Africa. This research was conducted to evaluate the potential for faecal sludge reuse in Malawi, and the difficulties and challenges to existing attempts at reuse in a city. We conducted 65 semi-structured interviews in a city of Malawi. The results show that two main approaches 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. Both existing approaches to faecal sludge management and reuse were found to be inaccessible and not working when implemented for the poorest and people with disabilities

A review of the financial value of faecal sludge reuse in low-income countries

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 healt

Why agricultural tools work in theory but aren’t adopted in practice: a grounded theory approach to ICT in Ghana and Kenya

Organic fertilisers could contribute to addressing the issues of declining soil fertility, food security and waste management by recycling human waste for use in sub-Saharan Africa. The variable nutrient content of such products can make targetted application more difficult than in chemical fertilisers. One solution to this could be the use of in-field soil testing and information, particularly with the expansion of mobile technology. This research investigated the role of information and soil testing in 43 farmers using human waste derived fertilisers in Kenya and Ghana. Interviews were conducted to understand the use and sources of information in farming and the perception of soil testing technologies. It was found that mobile based testing was unlikely to be adopted for reasons of low priority, the type of knowledge being shared and trust after failures of different projects. Farmers did not see soil testing as the major issue that they needed to solve. Mobile technology was mostly used for visual and oral communication whereas soil testing often provided information in an unsuitable way. Farmers also had limited trust in new projects as they had previously had project failures that did not help them. In order to achieve sustainable adoption of technology there needs to be improved methods of disseminating and learning from project failures to prevent repeated attempts at inappropriate technology in the future

An analysis of in‐field soil testing and mapping for improving fertiliser decision‐making in vegetable production in Kenya and Ghana

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