Impact of untreated wastewater discharges from high-rise buildings on the water quality of the Niger river in Bamako

Rapid urban growth in Bamako, characterized by the proliferation of high-rise residential buildings (S+R+6 and above), has led to a significant increase in domestic wastewater production. In the absence of adequate collective sanitation systems, a large proportion of this wastewater is discharged untreated into the Niger River, the main receiving water body of the city. This study assesses the environmental impact of untreated wastewater discharges from high-rise buildings on the physico-chemical quality of the Niger River and demonstrates the effectiveness of prior treatment using a faecal sludge treatment plant (FSTP). A comparative approach was adopted, combining field sampling, laboratory analyses, and compliance assessment against international standards. The results reveal substantial degradation of river water quality downstream of discharge points, marked by elevated biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), suspended solids, and nutrients. After treatment, a significant reduction in pollutant loads was observed, with effluent quality approaching international guideline values. The findings highlight the urgent need for structured collective sanitation solutions for high-rise buildings and provide valuable insights for sustainable urban water management in West African cities.