Management of domestic sewage and runoff poses enormous problems in major cities of Benin. These waters are mostly dumped in the streets or gutters that drained them to make referrals for various rivers without any treatment, causing the chemical pollution of these.
This study focused on the physicochemical characterization of household sewage and runoff from the city of Cotonou and the impact of the spill on their chemical quality of the channel of the city. Indeed, they are water troughs and water seeping from very heterogeneous and harmful to human body wastes deposited by residents on the banks of the channel. These wastes contain sources of phosphate, sulfate, chloride and nitrate from the decomposition of nitrogenous.
The results of this work indicate the parameters analyzed for the following values: dissolved O2 (1.5 to 3.2) mg / L; BOD5 (165 to 940) mg/L ; COD (350 to 2250) mg / L; NO3- (1.1 to 3.8) mg/L ; NO2- (0,07 to 2,6) mg/L ; PO43- (1.0 to 3,6) mg/L.These values are very high and demonstrate the levels of physical and chemical pollution enough pronounced of the water of the channel. The quality of the channel's water is mortgaged. This raises a number of measures to clean up it.