Impact of a domestic wastewater treatment plant on groundwater pollution, north Jordan

Abstract

An assessment of groundwater pollution in the area surrounding a domestic wastewater treatment plant in northern Jordan has been carried out. Groundwater in the study area is classified as alkaline earth water with increased portions of alkalis and prevailing chloride, tending to shift to alkaline water with the dominance of chloride. This trend indicates mixing between the two end members of fresh Ca2+-HCO3– water and saline Na+-Cl– water. Spatially, the highest concentrations of the hydrochemical parameters were found in close proximity of the Al Ramtha Wastewater Treatment Plant (RWWTP). Nitrate, which is the most common human-introduced pollutant into groundwater resources, was used to evaluate pollution of phreatic groundwater in the study area. Its concentration (as NO3–) ranges between 1 mg/L and 366 mg/L, with an average of 79 mg/L. A total of 71% of the samples present nitrate concentrations exceeding the threshold value for anthropogenic sources (20 mg/L), and more than 50% in excess of World Health Organization (WHO) standards for drinking water (50 mg/L). The most important factors affecting the magnitude of groundwater pollution are depth to groundwater table, aquifer transmissivity (hydraulic conductivity), lineaments density, and distance from treatment plant with calculated correlation coefficients of -0.51, 0.65, 0.70, and -0.75 to nitrate concentration, respectively.