Biological Characteristics of Septic Tank Sludge Treated With Calcium Oxide in Kinshasa, Democratic Republic of Congo

Purpose: The purpose of this study is to analyze the influence of these elements on the quality of sewage sludge. The subject of this study is manual sewage sludge collectors who typically use a natural site, such as a hole dug in the ground, as a place to deposit sewage sludge. Methodology: This laboratory study evaluates sewage sludge treated with calcium oxide (quicklime) to reduce pathogenic contamination. Samples were analyzed at 10%, 15%, and 20% CaO levels, assessing pollution markers like total bacteria, fecal coliforms, streptococci, staphylococci, and helminth eggs. Effectiveness was measured by reduction rates, confirming CaO’s potential to improve sludge safety for environmental management. Findings: The results of the experiment conducted with the 20% treatment are promising. Indeed, data analysis revealed a remarkable reduction rate, varying between 98.00% and 100%, for the bacteriological parameters. The quantities of sewage sludge and lime, their physical state, temperature, pH, contact time, and inhibitors are parameters that influence the speed of this reaction. The results of the study show that chemical treatment with calcium oxide has the potential to reduce the risk of biological contamination. The solid residues from the septic tank sludge treatment process can be used as fertilizer for agricultural soils. Unique Contribution to Theory, Policy and Practice: This research is of major interest to all those involved in septic tank emptying and researchers interested in this field, as it addresses an aspect of environmental protection practices in the city of Kinshasa that has been overlooked until now.