Caractérisation bactériologique des eaux résiduaires brutes de la ville de Cotonou (Bénin)

Abstract

Objective: The current study aims to assess the fecal pollution of the wastewater of Cotonou, the most populated city of Benin.
Methodology and Results: Three stations corresponding to discharge point of three main sewers have been sampled during 11 months from January to November 2013. Temperature, pH, electric conductivity and dissolved oxygen were measured in situ. Counting of fecal contamination indicator bacteria was carried through seeding method by incorporation in specific nutritious media. Counts of different bacteria numbered were out of standards and reached respectively 4.32.10⁶, 1.30.10⁷, 4.30.10⁶ and 7.90.10⁴ UFC/100ml for Escherichia coli, total coliforms, fecal streptococci and anaerobic sulphite reducers. Physico-chemical parameters values were not likewise up to standards of pouring but favourable, for the most, to suitable growth of microorganisms.
Conclusions and application: Studied wastewaters are high loaded in fecal germs. This indicates an important fecal contamination, potential epidemic source. Their purification appears necessary before pouring in environment in order to raise the threat which they constitute for people’s health.

Keywords: fecal pollution; wastewaters; main sewers; Cotonou.