Characterization of Well Water, Borehole Water and Wastewater in the Port Zone of Lomé: Physicochemical, Microbiological and Bioassay Approach

This study characterizes the physicochemical and microbiological quality of well water, borehole water, wastewater and water of the 4^th lake in the port zone of Lomé. Fourteen (14) water samples were collected following usual sampling standards. Physicochemical analyses covered turbidity, conductivity, pH, nitrogen compounds, and trace metal elements, and biodegradability. Microbiological analyses targeted heterotrophic bacteria, thermotolerant coliforms, salmonella, and clostridia and performed according to the standardized methods of the French Association for Standardization. A bioassay using the larvae of Artemia salina was carried out in order to assess the toxicity of the samples. Physicochemical analyses revealed a high conductivity in almost all the samples tested (>400 μS/cm). Ammonium concentration was very high in one of the borehole waters 1 (12 mg ${\text{NH}}_4^{+}$ /L). Nitrate concentration was high (>50 mg ${\text{NO}}_3^{？}$ /L) in well water 1, 2, 4, and borehole water 1. Biodegradability index was high (>3) in wastewater 1, 2, 3 and 4. Trace metal elements like arsenic (As) showed very high concentrations, above 10 μg/L, in wastewater 4. Microbiological parameters, of various well water and borehole water samples contained heterotrophic bacteria and thermotolerant coliforms (TC) at very high values. Clostridium (Clost) were found in the surface water samples while salmonella (Sal) was found only in wastewater 2, 3 and 5. The mortality rate of the larvae of Artemia salina was mainly high in the wastewater samples. Water samples of the port zone of Lomé, whether they come from wells, boreholes or wastewater, show clear signs of contamination. Groundwater use for domestic, hygiene and food purposes should be subject to prior treatment in order to improve its quality and to reduce health risks and wastewater’s heavy contamination underlines the urgent need for its appropriate management and treatment.