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From waste to health and wealth: transforming sanitation in Kenya

For the International Day of Women and Girls in Science we asked women leaders, scientists and innovators involved in the Newton Fund to share their stories and celebrate the impact of women in science.

Kenyan civil engineer Joy Riungu has developed a novel and cost-effective method of recycling human waste into animal feed and fertiliser. This simple intervention could transform sanitation in Kenya’s congested rural and urban areas.

Initially supported by the Newton Utafiti Fund through British Council, Joy is now being supported by the Royal Academy of Engineering’s Newton-funded Leaders in Innovation Fellowship training programme to commercialise the invention.

By Joy Riungu

When I was a young girl growing in a remote village in Kenya, the country’s low population meant that managing human waste wasn’t a problem. Today the population has quadrupled from 11 million to nearly 50 million people and Kenya’s sanitation systems are starting to buckle under the increased demand.

Technological interventions have not kept up with the growing population and we are failing to effectively manage the amount of human waste produced. The challenge is particularly bad among Kenya’s urban and peri-urban settlements, areas which are often illegal, unplanned and characterised by high levels of poverty. Poorly constructed or badly maintained pit latrines can leak human waste into the environment and present a significant health hazard.

Witnessing the sanitation situation worsen as I grew up, I became increasingly interested in finding a solution to the non-sewered sanitation problem – I wanted to find a way to deal with waste and improve the wellbeing of the general population.

‘A very friendly fly’: the solution to Kenya’s sanitation problems

What better way to manage human waste than to convert it into valuable resources? I thought to myself: who or what loves faeces? Flies! That was easy. But people don’t love flies that much – they spread diseases. Just when I thought this might be a dead-end, a simple search dug up a very friendly fly: the Black Soldier Fly. This species of fly is not attracted to human foods and and does not spread diseases. They are also very docile and easy to work with compared to house flies.

The Black Soldier Fly doesn’t feed as an adult but has a ravenous appetite at the juvenile stage, increasing its body weight 400 times within ten days of hatching and accumulating biomass that can be can be used for fish and animal feed or fertiliser.

When I realised the idea of using flies to recycle the human waste was achievable I was ecstatic! Now I just needed to secure some funding to get me started on this rather unconventional and unsavoury career path turning waste into resource! 

Securing funding and piloting the idea

After my application was rejected by several funding bodies (some doubted the Kenyan population’s acceptance of an idea that proposed recovering and reusing human waste), the Newton-Utafiti Fund saw the potential in my idea and granted me funding to pilot the concept.

I developed the project in collaboration with Aston University in the UK and drew on a wide range of expertise from fields including microbiology, mechanical and civil Engineering and business at Meru University of Science and Technology (MUST). We proposed 'a paradigm shift in faecal sludge management for food security and environmental management' which addressed human waste collection, transportation, treatment and final reuse challenges.

In September 2018 we piloted the idea at a primary school in Nchiru, Tigania West Sub-County. I had the idea to construct a system that separates urine from the stool. The system preserves water, as none is needed to operate them, and prevents ground and surface water pollution. Waste was collected from these toilets on daily basis and transported to a central treatment unit at the university where it was converted to valuable resources using the Black Soldier Fly (BSF) technology. Every 100kg of human waste was converted to 40kg protein, in the form of BSF larvae and 25 Kg of manure.

Image credit: Joy Riungu

There is already a huge market for the products produced by our project. The only limiting factor is that currently there aren't enough bio-resource complexes to facilitate collecting human waste from the community. Despite this, the pilot results demonstrate that resource-based sanitation has an essential role to play in addressing the menace of human waste. We modelled the pilot be implemented across all counties in Kenya, and it can be replicated in other developing countries facing similar challenges.

Revolutionising the way we think about waste

After successfully piloting the intervention, I set about disseminating the results. This was the easy part: everybody wanted to hear about this brave woman carrying kinyesi (faeces)! So much so that when I launched the concept at the agricultural exhibition in Kenya, my stand was rated as the best stand in research and innovation. It even captured the attention of the Kenyan Cabinet Secretary for Ministry of Agriculture, Livestock and Fisheries, Mwangi Kiunjuri.

The project has been reported in national media and the project is being further supported by the Royal Academy of Engineering’s 2019 Leaders in Innovation Fellowship (LIF) programme. Ensuring that effective sanitation services are accessible to the whole population is my ultimate goal and the LIF programme is another step towards achieving it. My motto is: From waste to health and wealth: join the sh*t revolution! I want to revolutionise the sanitation sector in Kenya and beyond, and be a voice for the underprivileged members of the community.

Joy Nyawira Riungu is a Lecturer in Water and Waste Water Engineering within the Civil Engineering Department at Meru University of Science and Technology (MUST).