TITLE:
Evaluation of the Effect of Using Sewage Sludge Compost as an Organic Soil Amendment on the Microbiological Quality of Bell Peppers (Capsicum annuum L.) in the Tropical Environment of Côte d’Ivoire
AUTHORS:
Bomassaye Roland Taho, Kouakou Ahossi Konan, Kra Athanase Kouassi, N’Dri Jacob Kouassi
KEYWORDS:
Capsicum annuum L., Faecal Sludge Compost, Microbiological Quality, Food Safety, Hygiene Indicator Microorganisms
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.17 No.9,
September
22,
2026
ABSTRACT: Introduction: The agricultural valorization of faecal sludge-derived composts represents a promising strategy for improving soil fertility and promoting sustainable waste management in sub-Saharan Africa. However, their use in crop production requires prior assessment of their agronomic characteristics and microbiological safety to limit potential risks associated with the transfer of undesirable microorganisms to edible crops. Objective: This study aimed to evaluate the physicochemical and microbiological characteristics of faecal sludge-derived composts before field application and to assess the effects of compost type, application rate, and planting density on the microbiological quality of sweet pepper (Capsicum annuum L.) fruits produced under tropical field conditions in Daloa, Côte d’Ivoire. Materials and Methods: Four composts produced from faecal sludge collected at different sites, including Bédiala Road landfill (CB), Bra Kanon (CBK), Garage neighborhood (CG), and Soleil neighborhood (CS), were characterized before application based on physicochemical parameters (pH, C/N ratio, organic matter, and nutrient contents) and microbiological indicators. Their effects were evaluated in comparison with mineral fertilization (NPK). At a fixed compost application rate of 30 t/ha, three planting densities (40 × 50, 50 × 50, and 50 × 60 cm) were evaluated. In a second experiment, planting density was fixed at 50 × 50 cm and compost application rates of 20, 30, and 40 t/ha were assessed. Microbiological analyses of sweet pepper fruits included aerobic mesophilic bacteria (AMB), total and thermotolerant coliforms, yeasts and molds, coagulase-positive staphylococci, Escherichia coli, and Salmonella spp., according to ISO standards. Data were analyzed using analysis of variance (ANOVA) followed by Tukey’s multiple comparison test at a 5% significance level. Results: After four months of composting, all composts showed physicochemical characteristics consistent with satisfactory stabilization, with pH values ranging from 7.11 to 7.30 and C/N ratios between 16.2 and 20.2. Their organic matter contents (22.7% - 29.5%) and nutrient composition indicated valuable agronomic potential. Microbiologically, Salmonella spp. was not detected and Escherichia coli levels remained below the detection limit (4 to 955.00 ± 10.90 × 104 CFU/g, while total coliforms reached a maximum of 8.75 ± 0.12 × 104 CFU/g. Thermotolerant coliforms, yeasts and molds, and coagulase-positive staphylococci also showed significant variations among treatments (p E. coli remained below the detection limit (Conclusion: The findings indicate that the use of faecal sludge-derived composts influenced the levels of several hygiene and spoilage indicators in sweet pepper fruits, while no contamination by the major enteric pathogens investigated was detected. Under controlled composting conditions and appropriate agricultural practices, these composts may represent a promising alternative to mineral fertilization for sweet pepper production. Nevertheless, appropriate monitoring of microbiological quality remains necessary to ensure the safety of crops fertilized with these organic amendments.