Environmental impact assessment of inland purification and desalination plants: case study of Al Asyah plant, Qassim region, Central Saudi Arabia

摘要

The impact of reject brine chemical composition and disposal from Al Asyah inland desalination on soil and groundwater was evaluated. The reject brine is disposed directly into a surface impoundment in a permeable soil with low clay content. Samples were collected from four evaporation ponds and chemically analyzed. The total dissolved salts (TDS) and the concentration of radioactive constituents were quantified. The results indicate high concentrations of TDS in the evaporation ponds where it ranges from 9650 to 15,460 mg/l. The majority of TDS include sodium chlorides produced throughout the isolation process of fresh water from brine. Moreover, the radioactive isotopes of radium-226 and radium-228 have been identified with total concentrations of 78.89 and 198.77 (pCi/l), respectively. These concentrations may be increased over time due to increasing of radon accumulation in the filtration sands. These results indicate that these constituents are above the standards set by the Gulf Cooperation Council and the Saudi National standards for drinking water and effluents discharged into the desert. Hence, reducing of the environmental impact resulting from both the radioactive materials and the ratio of salinity in water is of utmost importance for Al Asyah plant. Furthermore, the continuous monitoring of the effects of radioisotopes on the validity of the adjacent groundwater is highly recommended.