Physico-chemical Characterization of Wastewaters Discharged into Songolo River at Pointe-Noire, Republic of Congo

Songolo River receives daily domestic and industrial wastewaters from households, laboratories, small and medium size industries (SMEs) and the Loandjili hospital, which are discharged directly into it without prior treatment. The objective of this study is to evaluate the physico- chemical quality of wastewaters discharged into the Songolo River at Pointe-Noire in Republic of Congo. To do this, 56 wastewater samples were taken. Physicochemical analyzes as temperature, pH, electronical conductivity, total dissolved solids, chloride ions, nitrate ions and total hydrocarbons, were carried out on wastewaters. These analyzes showed that in terms of time, during wet periods (April to June), the values of the physico-chemical parameters (conductivity, total dissolved solids, chlorides ions, nitrates ions and total hydrocarbons) are the lowest due to the dilution phenomenon brought by the rains. On the other hand, the beginning of the dry season (July) is marked by much higher levels. The results of physico-chemical analyzes of these effluents also revealed that conductivity, total dissolved solids and total hydrocarbons often have values higher than those recommended by the WHO standard for wastewaters intended for release into the natural environment.