PHYSICOCHEMICAL CHARACTERIZATION OF THE WATERS OF THE LUKALA RIVER SUBJECTED TO INDUSTRIAL DISCHARGES FROM THE LUKALA CEMENT FACTORY (KONGO CENTRAL, DRC)

Surface water pollution from industrial activities is a major environmental issue in developing countries, particularly in the Democratic Republic of Congo, where mechanisms for controlling industrial discharges remain limited. This study aims to characterize the physicochemical quality of the Lukala River, a waterway that receives industrial effluents from the Lukala cement plant, located in Kongo Central province. Water samples were collected upstream and downstream of the industrial discharge point during the dry season of 2024. The parameters analyzed included pH, temperature, electrical conductivity, total dissolved solids (TDS), turbidity, total suspended solids (TSS), dissolved oxygen (DO), biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), nutrients (NH₄⁺, NO₂⁻, NO₃⁻, PO₄³⁻), as well as certain major ions and heavy metals (Ca²⁺, Mg²⁺, Fe, Pb, Cd, Ni). The results reveal a significant degradation of the physicochemical quality of the water downstream of the cement plant, characterized by an increase in alkalinity, conductivity, suspended solids, and organic load. Several parameters exceed the standards recommended by the World Health Organization (WHO) for surface water intended for domestic use. These results highlight the significant impact of the cement plant's industrial discharges on the Lukala River and underscore the need to strengthen environmental management measures and industrial effluent treatment.