Environmental hazards of wastewater disposal on groundwater at the West Sohag site, Egypt

Effluent infiltration from wastewater treatment plants into groundwater systems can be a source of contaminants of emerging concern that are not fully removed during the treatment processes. In the lowland desert area in Upper Egypt between the Eocene Limestone plateau and the new floodplain, wastewater disposal plants have been set up. Woody farmland will be irrigated with the treated wastewater. Some wastewater disposal sites, including the west Sohag site, have been operating since 1990. This site is considered a very hazardous source of soil and groundwater pollution. The current work aims to assess the environmental impact of the sewage water treatment plants (west Sohag site) in the Sohag Governorate, Egypt, using remote sensing and geochemical techniques. Monitoring the continuous extent of sewage water leakage and heavy metal mobility in the groundwater. The detailed visual interpretation of the different remote sensing data showed that the contaminated areas increased substantially. The area was classified into four classes, namely Urban centers, agricultural areas, water courses, and barren lands. The study showed that insufficient land is available to accommodate the projected quantities of wastewater. The hydraulic conductivity varies between 0.29 and 3.72 m/day with an average porosity of 38.9%. Excess raw wastewater accumulates on the ground surface at current operating sites, forming large, uncontrolled ponds. When soil, crops, and water supplies are contaminated chemically and bacteriologically, such ponds pose a risk to the ecosystem and could have catastrophic health consequences. Average heavy metal concentrations in the analyzed groundwater decreased from Zn > Cu > Pb > Cd, with mean values of 8.55 > 0.421 > 0.282 > 0.207 ppm, respectively. The correlations between heavy elements in the water are very high, with correlation coefficients greater than 0.8 between Pb & Cd, Pb & Cu, Pb & Zn, Cd & Cu, Cd & Zn, and Cu & Zn. According to speciation analysis, Zn, Cu, Pb, and Cd are highly mobile metals in the study area. Our findings confirmed the occurrence of sewage water leaking into the groundwater aquifer in the study area. These results offer useful data for examining the transport properties of heavy metal contaminants and developing practical remediation strategies.