“Exposure Assessment and Risks related to Trihalomethanes in Drinking Water of Greater Cairo Region"

Abstract

Water sources are not suitable for drinking because it is contaminated by several forms of contamination (physical, chemical and biological contamination) and due to human activities (sewage, industrial and agricultural waste) beside exposure to the atmosphere. Water sources used for supplying water should be treated to meet a specific criteria or standard to ensure that water supplied to the public is safe and free from pathogenic microorganisms, hazardous compounds and any other contaminants. There are many water treatment plants have been established in Egypt for treatment of surface water and ground water by conventional water treatment. Conventional water treatment include many steps started by screening filtration to remove large particles, coagulation that happened in the clarifier using coagulant like alum which collect hardness particles on their surface to form flocs (Flocculation) then sedimentation for these flocs and disinfection by addition of chlorine to inactivate pathogenic microorganisms then filtration by sand filters. Disinfection process is the most important process in the treatment of drinking water supplies since it eradicates or inactivates pathogenic microorganisms responsible for waterborne diseases (Bacteria – Viruses).