This study, carried out in San Pedro (Southwest Côte d’Ivoire), evaluates the agronomic valorization of wastewater treatment sludge (WTS) and green waste (GW) through co-composting for sustainable soil improvement and circular economy promotion. Four GW/ WTS formulations (Co1: 0/100, Co2: 25/75, Co3: 50/50, Co4: 75/25) were monitored over 90 days, with regular measurements of temperature, moisture, and pH. Mature composts were characterized for physico-chemical properties, biological maturity, and heavy metal content. A weighted multicriteria matrix, based on ten strategic indicators, identified Co3 as the optimal formulation (score 40/45), outperforming Co4, Co2, and Co1. Co3 reached 65 °C by day 40, satisfying sanitary requirements, maintained optimal moisture, increased soil organic carbon by 284 %, corrected pH to 7.9, and complied with NFU 44-051 heavy metal standards. The heatmap and hierarchical clustering analysis confirmed its superiority, positioning Co3 as a safe and effective amendment for sustainable agriculture adapted to local soils.

In Côte d'Ivoire, cocoa beans production (2,248,000 tons in 2020/2021) generates huge quantities of pod residues that are abandoned in the cocoa plantations, promoting the spread of diseases, such as brown pod rot. The objective of this study was to assess the availability of shelling residues and to describe the different utilization in cocoa farming. A survey was conducted with 125 producers in four departments of high cocoa production. The results showed that the production of 480.19 kg/ha/year of beans generated 960.40 kg/ha/year of shells. The crushing residues used are the shells (44% of the producers), the rachis (13.6%) and the mucilage juice (100%). The shells are spread under cocoa trees and/or banana trees (22.4%), are composted (8.8%) or used for manufacturing potash (7.2%). The rachis are displayed under the cocoa trees or used in animal nutrition. The juice is sometimes mixed with herbicides to control weeds on farms. This study showed that there is a large quantity of shelling residues available, but the rate of use is still low. Improving valorization practices would contribute to sustainable agricultural production as well as reducing sanitation problems in cocoa farms.