Groundwater Quality in an Alluvial Aquifer Affected by the Anthropogenic and Natural Processes in a Rural Area, North Algeria

Abstract

The impact of individual septic tank effluent on groundwater quality was investigated in the rural area of the Ain Soltane municipality. The septic tank is a solution for the pre-treatment of sewage. It ensures the partial liquefaction of concentrated pollutants in wastewater and the retention of solids and floating waste. The alluvial gravel aquifer of the Cheliff Plain is especially susceptible to microbial contamination due to the significant number of septic tanks and the high quantity of pre-treated wastewater passing toward the groundwater which may transport bacteria and contaminants over large distances. Geological investigations established the presence of limestone carapace, and stones with high thickness and good permeability, which forms an unconfined aquifer in the area. Groundwater quality monitoring showed a significant degree of an organic pollution in the majority of wells, with very high concentrations of sulfate and chloride exceeding 450 and 250 mg/L, respectively. It also showed the presence of bacterial germs in the groundwater whose origin are fecal, so these monitoring wells are contaminated and are unfit for drinking in this area. The presence of these pathogen germs poses a major problem for public health. This study has identified the effects of septic tank effluent on groundwater quality in Ain Soltane area.