TITLE:
Study of the Treatment and Valorization of Ash from the Incineration of Solid Biomedical Waste
AUTHORS:
Mireille Laura Wondja Ngoko, Ilie Johana Ondigui Mengue, Raissa Etong Nkomba, Séverin Mbog Mbog
KEYWORDS:
Biomedical Waste, Ash, Stabilization, Agricultural Valorization, Bean, Heavy Metals, CHUY
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.7,
July
23,
2026
ABSTRACT: The management of biomedical solid waste poses a major environmental and health challenge in Cameroon due to the hazardous nature of incineration ash. This study, conducted at the Yaounde University Hospital Center (CHUY), focuses on the treatment and valorization of this ash as an agricultural amendment. The methodological approach was structured around three fundamental axes linked to specific objectives. The first objective was physicochemical and toxicological characterization; macroelement and heavy metal concentrations were determined by atomic absorption spectrometry. After mineralization, and supplemented by a standardized leaching test (TCLP), pollutant mobility was assessed. Regarding the second objective, stabilization, the methodology relied on a stabilization/solidification process using lime (Ca(OH)2) for its neutralizing properties and chicken manure as an organic complexing agent. Finally, for the third objective, dedicated to evaluating fertilizer potential, an agronomic experimental design in a controlled environment was implemented on bean cultivation, comparing different formulations (F1 to F4) with negative controls and chemical fertilizers (NPK). The results obtained reveal significant chemical complexity. Regarding the first objective, characterization highlighted a highly alkaline pH of 11.22 and exceptional mineral richness with high levels of Calcium (185.4 g/kg), Potassium (42.1 g/kg), Phosphorus (12.8 g/kg), and Magnesium (8.2 g/kg). However, the metallic load exceeds critical thresholds with concentrations of lead (0.14 mg/kg), copper (1.20 mg/kg), zinc (16.37 mg/kg), and cadmium (12.4 mg/kg). The TCLP test confirmed this hazard with an initial lead release of 4.8 mg/L. Also, the stabilization protocol reduced this mobility, bringing lead release down to 0.8 mg/L, thus ensuring compliance with environmental standards. The agronomic trials show that formulation F4 (50% ash + 50% manure) is the most effective for beans, resulting in an average height of 18.7 cm, a fresh biomass of 21.7 g, and a leaf development of 4.3 leaves, surpassing the chemical control without exhibiting phytotoxicity. This work validates the feasibility of transforming biomedical ash into stabilized fertilizers, offering a sustainable solution that reconciles environmental protection and bean crop productivity in Cameroon.