Assessment of CO₂ Emissions from the Decomposition of Banana Peel Heaps Using a Closed Static Chamber at a Semi-industrial Processing Facility in Rwanda

Banana peel waste generated by semi-industrial food processing facilities in Rwanda is commonly discarded in open heaps, yet its contribution to greenhouse gas (GHG) emissions is not currently captured in national inventories. This study quantified carbon dioxide (CO₂) emissions from banana peel waste heaps and assessed the influence of peel age and short-term temporal variation on emission dynamics. Field measurements were conducted at ZEAN Ltd, located in Nyabihu District, Rwanda, using the closed static chamber technique over five non-consecutive sampling days in April 2026. Banana peels were classified into three age categories (<1 week, 2 weeks, and 4 weeks old), with measurements taken in triplicate for each category on each sampling day, resulting in a total of 45 CO₂ flux observations. Across all measurements, CO₂ fluxes ranged from −47.3 to 1294.9 mg CO₂ m⁻² h⁻¹, with a grand mean flux of 489.99 ± 307.89 mg CO₂ m⁻² h⁻¹, indicating substantial spatial and temporal variability. One-way analysis of variance (ANOVA) and the non-parametric Kruskal–Wallis test were applied to evaluate the effects of peel age and sampling day. Peel age did not show any statistically significant effect on CO₂ emissions (p = 0.740), suggesting that the decomposition stage alone is not a dominant driver of short-term emission variability under open-heap conditions. Alternatively, the sampling day significantly affected emission rates (p = 0.002), accounting for 33.9% of the total variance in observed fluxes. There was, a consistent reduction in CO₂ emissions across all peel age categories on the second sampling day, pointing to the overriding role of transient, site-wide environmental factors such as moisture availability, temperature, or atmospheric conditions. This study provides the first field-based CO₂ emission measurements from banana peel waste heaps in Rwanda and establishes an empirical basis for the development of site-specific emission factors. The findings underscore the previously unrecognized climate implications of current banana peel disposal practices and support the integration of waste valorization strategies, including composting and animal feed production, into agricultural waste management and climate mitigation policies. Incorporating such measures into Rwanda’s Nationally Determined Contribution (NDC) could enhance the accuracy of GHG reporting while promoting circular bioeconomy approaches. Key words: cooking banana, CO₂ flux, greenhouse gas inventory, Rwanda