Innovative ways African cities can cut methane from organic waste

From the newsletter

A new report by environmental NGO GAIA highlights three innovative ways municipalities can curb methane emissions from organic waste. The toolkit points to vermicomposting, black soldier fly processing, and landfill biocovers, which, when combined with more common approaches like composting, could cut emissions by up to 95%.

• Methane is a short-lived but highly potent greenhouse gas, with a 20-year global warming potential 84 times that of CO₂, making its rapid reduction vital for near-term climate mitigation.

• African cities generate large volumes of organic waste, often ending up in open dumps, producing significant methane emissions that threaten local air quality and contribute to rapid climate warming.

More details

• Published in September 2025, the report, Municipal Strategies for Organic Waste: A Toolkit to Cut Methane Emissions emphasises preventing organic waste from reaching landfills by prioritising diversion and resource recovery. Recognising that some waste may still end up in landfills, the toolkit also recommends landfill biocovers as a critical solution to mitigate methane emissions from existing waste.

• The report highlights a range of strategies to reduce methane emissions including composting, anaerobic digestion, use of organic waste as animal feed, vermicomposting, black soldier fly processing and landfill biocovers. While composting, anaerobic digestion and animal feed applications are already common in Africa, vermicomposting, black soldier fly processing and landfill biocovers remain less widespread but offer promising new pathways for sustainable waste management.

• Vermicomposting uses earthworms to transform organic waste into vermicompost, a stable nutrient-rich fertiliser, and vermileachate, a liquid byproduct that can be applied as a foliar spray or soil drench. Excess worms from healthy colonies can be harvested as a protein source for poultry or aquaculture or reused as seed stock for new systems. This method provides both environmental and economic benefits by reducing waste while producing valuable inputs for agriculture.

• Black soldier fly processing involves the controlled use of Hermetia illucens larvae to convert organic waste into protein-rich biomass and nutrient-rich frass. Larvae can reduce organic waste volumes by up to 80% producing larval biomass that accounts for 15–20% of the original waste and frass that makes up 30–40%, depending on the system design. The dried larvae are used as animal feed for poultry, aquaculture or pets while frass serves as an effective organic fertiliser, contributing to circular bioeconomy systems.

• On their part, landfill biocovers are compost or soil-based systems designed to enhance microbial oxidation of methane from landfills. Placed over aging or low-yield landfill cells, these passive covers consist of a gas distribution layer beneath an oxidation layer, typically made from mature compost or other locally available materials. By stimulating methanotrophic bacteria, biocovers can reduce methane emissions by 70–100% providing a low-cost low-maintenance solution for poorly managed or legacy landfill sites.

• These strategies are particularly relevant for African cities where budget constraints and limited waste infrastructure make high-tech solutions such as waste-to-energy incineration or landfill gas capture difficult to implement. Vermicomposting, black soldier fly systems and landfill biocovers provide scalable, adaptable and cost-effective options for local contexts.

• Beyond cutting methane emissions, these approaches create jobs in waste collection, processing and farming while promoting inclusivity by engaging communities, cooperatives and informal waste workers in decentralised systems.

Our take

• Key strategies could help transform Africa’s waste sector where rapid urbanisation coupled with limited waste infrastructure mean most organic waste still ends up in open dumps.

• The suggested strategies build on proven approaches, showing that Africa has ample innovative solutions to its waste crisis. What is needed now is implementation.

• While Africa’s methane reductions remain comparatively low, implementing scalable strategies like vermicomposting, black soldier fly processing, and landfill biocovers could unlock significant near-term climate benefits.