Évaluation de la composition physico-chimique et biologique des boues issues du traitement des eaux usées de savonnerie et de raffinerie de Pafic sarl, en vue de leur valorisation potentielle comme amendement agricole pour la culture du maïs, du soja et du manioc

Abstract

This study assesses the potential for using biosolids from PAFIC SARL's wastewater treatment plant as a fertilizer for crops, including maize, soybean, and cassava, by analyzing their physical, chemical, and microbiological characteristics. The company has multiple activities sectors generating industrial wastewater, including soap production, cosmetics, plastic manufacturing, beverages, and oil refining. Wastewater from these activities sectors undergoes a multi-stage treatment process involving pre-treatment (manual screening, sand removal), primary coagulation, and secondary physico-chemical treatment using aluminum sulfate. The biosolids produced were collected and analyzed for key parameters such as pH (6.82), conductivity (465 µS/cm), and nutrient content (total nitrogen: 165 mg/kg, phosphorus: 325 mg/kg). Notably, heavy metals were present, including zinc (349 mg/kg), lead (3.108 mg/kg), and chromium (20.4 mg/kg), althoug they were within acceptable agricultural limits. Microbiological analysis revealed moderate levels of fecal coliforms (240 UFC/100 ml), streptococci (153 UFC/100 ml), and the presence of Salmonella (3 UFC/5L), which poses potential sanitary risks for agricultural use. Recommendations for the safe use of these biosolids as a soil amendment include ensuring proper treatment and monitoring to mitigate microbiological risks and adjusting for potential heavy metal accumulation. The results highlight the potential of these biosolids to enrich soils with essential nutrients, although precautions are necessary to prevent environmental and health hazards, particularly in areas sensitive to heavy metal contamination. The findings underscore the importance of regulatory compliance and tailored treatment strategies for sustainable agricultural use.