Waste not what want not: Nairobi schools recruit flies to help

Around two and a half tonnes of organic waste are generated in Nairobi each day, much of it from kitchens, schools, farms and informal markets. Its disposal is a problem, an increasing problem. But what if this waste can be recovered? And used as a resource? 

In Africa, up to 40% of food is lost or wasted along informal urban supply chains because of inadequate infrastructure, poor handling and weak market linkages. The consequences go beyond the waste itself. Food loss and waste reduce farmers’ incomes, contribute to higher food prices and deepen nutritional insecurity, particularly among low-income urban households. Much of this organic waste ends up in dumpsites, mixed in with all other wastes and taking up valuable space. 

The World Vegetable Center (WorldVeg), together with the International Institute of Tropical Agriculture (IITA) and project partners including  Zehunger Solutions andicipe under the CGIAR Food Frontiers and Security Science Program are exploring the reuse of this organic waste, transforming it into valuable agricultural inputs through a Black Soldier Fly (BSF) initiative. The initiative is being piloted at Tassia School, Umoja 1 Primary School, Clanne Academy and the Kogongo Area Farmers Hub in Ruaka. By converting organic waste into protein-rich insect feed and nutrient-rich frass fertiliser, BSF technology is demonstrating how a waste challenge can become an opportunity for more sustainable, circular food systems, practical learning and agricultural production.

The concept is simple: separate organic waste, feed it to BSF larvae, harvest the larvae as animal feed and return the resulting frass to the soil. The Black Soldier Fly, Hermetia illucens, is particularly suited to this process. Its larvae consume organic materials such as kitchen waste and convert them into protein-rich biomass. The remaining material, known as frass, can be used as an agricultural input.

From Waste Bins to Biopods

Waste segregation is the critical first step. Separating biodegradable material at source creates a cleaner feedstock for BSF to feed on, while reducing waste contamination. The initiative is putting this approach into practice in schools and with farmer hubs, creating practical examples of how urban organic waste can be returned to food production. At the three pilot school sites, the project began with waste segregation. Schools received collection bins and training for learners, teachers and 4K Club patrons on separating organic from inorganic waste.

The schools then received BSF biopods and practical training on feeding, substrate preparation, hygiene, monitoring and harvesting. During May and June 2026, five-day-old larvae were introduced into the units, with each biopod receiving three kilograms of larvae. At the schools, kitchen waste collected by learners provides the main feedstock. At Kogongo, farmers use organic waste sourced from nearby markets and their livestock.

Learning from the Larvae

The BSF units have become living classrooms where lessons in biology, agriculture and environmental sustainability unfold in real time. Members of the 4K Clubs work alongside their patrons to prepare feed, manage the larvae and harvest the products. Vegetable demonstrations, including spinach, where the frass fertilizer is added, reinforces the connection between food waste, soil fertility and crop production.

The approach extends into the schools’ wider agricultural activities, linking vegetable gardens with poultry and rabbit keeping. Together, these activities demonstrate how waste from one enterprise can become a useful input for another, creating a simple, visible circular system.

Today, learners collect organic waste for the biopods and confidently explain the BSF cycle to visitors. For some, hands-on experience has sparked a level of curiosity and confidence that does not always emerge in the classroom. What began as a waste-management exercise has developed into a community learning experience. The interest is spreading beyond the learners. Teachers and parents have become intrigued and began asking about the BSF production and if it is possible at home. One Umoja parent has even suggested for a live demonstration during a parents’ meeting.

The first production cycle has also delivered tangible results. The schools harvested 19 kilograms of larvae at Tassia, 16 kilograms at Umoja and 15 kilograms at Clanne Academy, providing a practical source of feed for poultry and valuable lessons to inform the second production cycle. Building on these experiences, the schools have demonstrated significant improvements in larvae production, ranging from 30% to 60%, highlighting the potential for continued improvement in production efficiency and output. Building on this experience, the schools are preparing for a third production cycle focused on improved feeding, biopod maintenance, record keeping and additional training. Vegetable demonstration gardens further connect the journey from waste segregation to BSF production, frass recovery and food production. Peer exchanges between schools and exposure to established BSF production sites will strengthen practical skills and help take the lessons beyond individual classrooms.

From Local Waste to Local Solutions

For farmers, the value of BSF technology lies not simply in introducing a new innovation, but in finding solutions that fit their local conditions, available resources and farming needs. At the Kogongo Area Farmers Hub in Ruaka, farmers are putting this principle into practice. They are using organic waste from households, farms and nearby markets to produce BSF. Locally sourced waste is then converted into livestock feed, and at the same time reducing the organic waste in dump sites. The approach is deliberately contextual. Farmers are learning through practice, testing different waste streams, observing how their livestock respond to fresh larvae and exploring how the technology can fit into their existing farming systems.

Purity, one of the participating farmers, captures the enthusiasm among users, saying: “My pigs love the larvae so much they fight over them.” The simple observation highlights how BSF larvae are becoming a practical and appealing source of protein for livestock while providing farmers with an innovative way to convert organic waste into value.

Poultry farmers have similarly observed strong acceptance of live larvae by chickens, pointing to the potential of BSF as a locally produced feed resource. The project is also exploring how the frass fertilizer helps farmers’ crop production needs. Demonstration plots compare spinach grown with crude, granulated and pelletized frass against spinach grown without. Rather than prescribing a single solution, the trials allow farmers and project partners to physically observe what works, compare different formulations and identify options that are practical, affordable and relevant to farmers.

Scaling Nairobi’s Circular Model for Cities

As cities grow, so do the volume of organic waste. What is emerging in Nairobi is more than a collection of pilot activities. It is a practical model for demonstrating how urban organic waste can be recovered, transformed and returned to food production. The model is grounded in local realities. Schools are learning how to segregate waste, operate biopods and use the resulting products. Farmers are testing different feed sources, livestock applications and frass fertilizer formulations. These experiences are generating practical knowledge about what works, what needs improvement and what it takes to make BSF systems useful under different settings.

Scaling innovation is not simply about replicating a technology; it is about adapting solutions to the people, resources and conditions of each place. The lessons emerging from Nairobi can help inform how similar approaches might be designed and adapted in other rapidly growing African cities.

Dr.  Cecilia Limera, Programs Lead- Africa and Country Representative, World Vegetable Center 

The foundations for scaling are taking shape through hands-on experimentation, skills development, peer learning and locally adapted solutions. The next step is to strengthen the evidence, document what works and refine models that schools, farmers, youth groups and communities can adopt and sustain. The opportunity is significant. As cities grow, so does the volume of organic waste generate by households, schools, markets and businesses. At the same time, farmers need affordable sources of livestock feed and agricultural inputs. Connecting these challenges through circular solutions can help cities retain nutrients and value within their food systems.