The Environmental Impact Assessment of the Surrounding Area of the Water Treatment Plant in Aranah Valley in Makkah, Saudi Arabia

Environmental pollution is a serious issue due to its ecological risks and negative impacts on human health. Makkah city is one of the densely populated cities in Saudi Arabia. In addition, it receives yearly millions of visitors from different parts of the world, which may increase pressure on local resources, and may also may contribute to environmental pollution. Therefore, it is important to keep a safe and healthy environment in Makkah city in Saudi Arabia. This study aimed to assess the negative environmental impacts by analyzing the levels of heavy metals, physiochemical and bacteriological parameters in surface water, groundwater and soil samples collected in the surrounding area. Samples were collected for over one a year (May 2019–May 2020) and were analyzed for microbial and physicochemical properties. Mean concentrations of three heavy metals, Pb, Cr and Cd, (in ppm) were 0.007 ± 0.003, 0.009 ± 0.009 and 0.002 ± 0.001, respectively in surface water; 0.010 ± 0.004, 0.031 ± 0.011, 0.007 ± 0.002 in groundwater; and 0.013 ± 0.007, 0.730 ± 0.244, 0.008 ± 0.003, respectively in soil samples. The average pH of groundwater and surface water were 7.279 and 6.992, respectively. The average concentration of TDS for groundwater and surface water was 1441 ppm and 472.2 ppm, respectively and the average levels of F, Cl, Br, Na, Mg, NO2−, NO3−, PO43−, SO42−, Pb, Cr, Cd and As were 0.836, 121.8, 1.050, 3.083, 0.237, 0.000, 12.74, 0.732, 1.573, 108.8, 0.032, 0.007 and 0.00 ppm, respectively. The results indicated that treatment plants had no significant impact on the microbial, physicochemical, and heavy metal properties of the local soil and surface water when compared to the Saudi Ministry of Environment, Water and Agricultural (MEWA) and international permissible limits. Fecal coliforms and E. coli were detected in 92.3% and 38.5% of water samples respectively. The most probable number (MPN) of fecal coliforms and E. coli was very high in 50% and 8.3% of water samples respectively. The study concluded that the level of heavy elements in the surface water and soil samples in Aranah valley were within the permissible limits, while the levels of heavy metals in groundwater were higher than the local and international permissible limits. Thus, the contaminations from the wastewater treatment plant reached the groundwater in the studied area. The study recommended that the groundwater from the study area should not be used for drinking and agricultural purposes.