The aim of this work is to study the physical and chemical characterization of wastewater at the level of the student residences of the university’s campus of Abomey-Calavi in order to propose in the medium term an adequate system of treatment of these wastewaters. The study evaluate quantity of water used by students per day and the pollutant loads in them and the methods of storage and disposal of wastewaters of students residences. Showers, laundries and kitchens are the main systems that generate wastewater. The receptacles of these waters are the sumps which also receive wastewaters from the septic tanks of the toilets. These wastewaters are then rejected in the Nokoue lake. The approximate number of students wastewaters generator in residences is 3904. The amount of wastewaters produced daily and collectively by the residents of the university campus is approximately 292800L. From analyzes conducted on these waters, it appears that they have the characteristics of domestic wastewaters and the ratio COD / BOD5 shows that these wastewaters are little biodegradable. Moreover, they don’t comply with beninese standards for the discharge of domestic wastewaters. This huge amount of wastewaters is not without consequences on the health of campus users and the environment. The campus of university of Abomey-Calavi does not also have a wastewaters treatment system. Appropriate measures should be taken to improve the management of these wastewaters.

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.