Wastewater management practices in Porto-Novo, Benin

Abstract

The Porto-Novo lagoon is the main receptacle of all wastewater in the municipality through gutters. The objective of the study was to analyze the wastewater management system of the municipality of Porto-Novo to assess the risks of their discharge without treatment in the lagoon. For this purpose, a characterization of wastewater was carried out after a household survey. The results obtained reveal that houses accounted for the most abundant source (55.8%) followed by workshops (21.9%). 94%, 92%, 79% and 50% of respondent households, respectively, discharged laundry water, dishwater, shower water and blackwater in nature. 42.5% of respondent households had access to an appropriate sanitation system. Latrines and showers were the most used sanitation structures in Porto-Novo. The principal component analysis revealed three groups of wastewaters: wastewater from slaughterhouses, workshops and human settlements. Physicochemical and bacteriological analyzes indicated that wastewater had organic and microbiological contamination and then were outside WHO and Benin standards. The majority of the parameters studied varied significantly between the types of wastewaters. The wastewaters from the workshops (DCO / DBO₅ > 5) were non-biodegradable while the wastewater of slaughterhouses and human settlements (COD / DBO₅ <3) were easily biodegradable. This situation could have repercussions on the quality of the water bodies of this municipality, exposing aquatic communities and local populations to ecotoxicological risks. Thus, this wastewater requires prior treatment before being released into the environment.

Keywords: Wastewater, Sanitation, Management, Discrimination, Porto-Novo, Benin