Together with partners in Ethiopia, Rwanda, the Democratic Republic of the Congo and South Africa, ETH Zurich researchers are creating circular economies that use processed organic waste and human excreta as fertilizer or animal feed, resulting in higher crop yields and new jobs.
Around 250 million Africans - 1 in 5 people on the world's second-largest continent - suffer from hunger or malnourishment. One reason for this is that agricultural soils have not been receiving enough nutrients. As a result, crop yields are declining. At the same time, many cities in sub-Saharan Africa face challenges with their sanitation and solid waste management. In many places, rapid urbanisation is overstraining the waste and sanitary infrastructure.
Usually, researchers regard these two problems as separate issues. This is not the case, however, in ETH Zurich's Sustainable Agroecosystems research group, led by Professor Johan Six: "We want to establish regional circular economies in which local people reuse nutrients from faecal matter and organic waste as fertiliser for growing food or as animal feed," he says.
In collaboration with ETH Zurich's Transdisciplinarity Lab (TdLab), Six's group has since 2019 been leading the Runres research for development project, which is funded by the Swiss Agency for Development and Cooperation (SDC). The researchers and their local partners in Ethiopia, Rwanda, the Democratic Republic of the Congo, and South Africa have shown that they are able to improve food security as well as waste management by recycling organic waste in a clever way. Local entrepreneurs' direct and active involvement in these projects has created new jobs, particularly for women.
Compost from human excreta and organic waste
In many rural areas of South Africa, people still dispose of their human excreta in pit latrines. This poses a great challenge for municipalities as the latrines fill up quickly. It also increases people's risk of coming into contact with pathogens.
Benjamin Wilde, a native of Texas and a postdoc at the Chair of Sustainable Agroecosystems, is trying to solve this problem together with local partners in the Msunduzi municipality: "We're working with the local company Duzi Turf, a public utility, and the municipality to produce compost from sewage sludge and urban green waste. This is then used as fertilizer," Wilde says. He coordinates RUNRES from Zurich.
While the municipality supplies the green waste and the public utility company the sewage sludge, the company is responsible for the composting. This collaboration of public and private actors, however, does more than just empty latrines: the organic fertiliser also enhances soil fertility and thus increases local farmers' crop yields. The compost is used to fertilize green spaces as well as the fields of a neighboring farmers' cooperative, increasing its agricultural yields. What's more, the local company creates new jobs by selling the compost.
Similar to South Africa, the Runres project in Bukavu, a city in the eastern Democratic Republic of Congo, is about producing compost from organic waste. To improve the collection of this waste in the city, Runres social scientist Leonhard Spaeth worked with researchers from the International Institute of Tropical Agriculture (IITA) to conduct an education campaign that encouraged residents to better separate household organic waste. "Sorting behavior at household level is essential for getting an efficient and cost-effective process-chain from waste to usable input for the agriculture", Spaeth explains. This work is not only improving waste management in the city, but also public health. The compost is then sold to local coffee farmers, where it is used as fertilizer.
Sustainable animal feed from organic waste
Recycling organic waste is central to another Runres project as well. In Kigali, Rwanda's capital city, the ETH Zurich researchers are working together with a local company that collects organic waste and feeds it to the larvae of the black soldier fly.
"The larvae eat the organic waste and convert it into their own biomass. They are an excellent source of protein for livestock such as chickens or fish," Wilde says.
Rwanda still imports most of its animal feed from abroad. Small farmers cannot afford these expensive imports. The fly larvae are a cheap and locally produced alternative that creates jobs and reduces waste management costs.
This new source of animal feed also counteracts overfishing; up to now, poultry and fish farmers have mainly used fish from local lakes to feed their livestock.
A banana-based circular economy
The ETH Zurich researchers are also involved in a Runres project in Arba Minch, a city in the south of Ethiopia. This area is a big banana-growing region. Many farmers send their raw bananas to Addis Ababa, the capital of Ethiopia, where they are then sold to urban consumers. Being at the bottom end of the value chain, the farmers themselves make very little money.
Over the past two years, the ETH Zurich researchers have established a factory to produce value added banana products such as flour and banana chips together with a local business. The company sells these products directly to supermarkets, schools and hospitals.
"Due to the higher profit margins, the company can pay farmers a higher price for their bananas. That means more added value and, ultimately, more jobs stay in the region," Wilde says. The company is also planning to make baby food from bananas, which will further increase the value added.
As fertiliser, the banana farmers are now using compost made from organic waste by another company that is also part of the Runres project. This company is also using the potassium-rich banana peels produced by the banana processing facility to make compost and animal feed. In keeping with the Runres ethos, all these innovations lead to a regional circular economy that recycles waste and uses it as fertiliser in agriculture.
Local partners are involved from the start
Not only is the Runres project improving the income and living conditions of the local population; the way in which they have been carried out is also new: In each of the four African countries where Runres operates, it employs at least two well-connected local project assistants who have intimate knowledge of the country. Together with the ETH Zurich researchers, they identified players from the worlds of business, politics and administration who might be interested in setting up a circular economy.
These potential partners then met on transdisciplinary innovation platforms moderated by Runres staff. "Rather than approach local players with ready-made solutions, we developed and implemented innovations with them," says Pius Krütli, the co-director of ETH Zurich's TdLab. "What is special about this is that the local partners also participate financially right from the start. With this approach, we not only share responsibility, but also create a common knowledge base and create ownership among the local actors." The researchers focused on companies that stood to benefit from these innovations and were therefore motivated to commit to the project.
During the project's initial phase, which ends in the first half of coming year, the researchers aim to demonstrate that their concept of regional circular economies works: soil health is building, while waste water management has improved; agricultural yields are increasing, while new jobs are being created and the exchange of knowledge and experience is working.
In the second phase, which will last until 2027, the ETH Zurich researchers and their partners in Africa intend to expand their projects. The goal is for them to become self-sustaining activities - without SDC assistance.
