ABSTRACT
Mostorod Drinking Water Treatment Plant [Mostorod DWTP] is one of the biggest water treatment plants in Cairo. The intake of Mostorod DWTP is located 8 km from the beginning of Ismailia Canal and this region is polluted with organic compounds such as alkanes, PAHs and chlorinated hydrocarbons. Mostorod DWTP serves east of Cairo especially Masr El-Guidida, Nasr City, El-Mazallat and North Shubra regions and its distribution system expands for more than 100 km[2]. It applies conventional treatment like other water treatment plants in Egypt. Samples were collected after 3 different steps in Mostorod DWTP [after sedimentation, after filtration and after post-chlorination]. The concentration of n-alkanes, PAHs and chlorinated hydrocarbons were determined and the removal percent after each step was calculated. Pre-chlorination and sedimentation steps had the highest removal for organic compounds followed by post-chlorination step due to usage of chlorine as disinfectant and its role in oxidation of organic compounds. Filtration step had the lowest removal for organic compounds due to absence of oxidants in this step. Traces of organic compounds are still present is storage tank of Mostorod DWTP due to insufficient oxidation