Characterization of the sludge drain and risks of groundwater pollution : The case of the cities of Katiola, Bouaké and Bouaflé (Côte d'Ivoire)

The proximity of water wells to faecal sludge storage facilities could be a source of contamination for these wells. Thus, the aim of this study was to characterize faecal sludge and well water in order to assess the effect of faecal sludge on the level of pollution of wells water in Katiola, Bouaké and Bouaflé. To do this, selective physico-chemical and microbiological analyses were carried out on faecal sludge and well water from each town, and the principal component analysis method was used to establish the link between sludge and well water. The results showed that Bouaké's well water was poorly mineralized and rich in nitrite. Well water from Katiola was moderately mineralized, rich in ammonium and contained the highest bacterial loads. At Bouaflé, water from wells was highly mineralized, rich in nitrates and ammonium. Sewage sludge from Bouaké and Katiola is characterized by high levels of nitrites, nitrates, ammonium, total phosphorus, Total Nitrogen Kjeldah (NTK), conductivity, total dissolved solids, pH and bacteria. Those at Bouaflé are characterized by high values of dissolved oxygen, redox potential and biochemical oxygen demand (DOB5). The present results show that there is a relationship between well water pollutants and sewage sludge in these localities.