TREATMENT OF LAKES WATER CONTAMINATED BY POLYCYCLIC AROMATIC HYDROCARBONS USING HYDRODYNAMIC CAVITATION

Polycyclic Aromatic Hydrocarbons (PAHs) are considered Persistent Organic Pollutants (POPs). The presence of these pollutants in the aquatic environment constitutes a significant danger to living organisms because they are difficult to decompose and cause cancer and genetic mutations. Therefore, they have become a concern in many countries, and effective methods must be found to remove them from the water. In this paper, the removal of PAHs in Sureat lake water was studied. Water samples were taken and analyzed using Gas Chromatography / Mass Spectrometry (GC/MS) to determine the concentrations of PAHs. The total concentration of PAHs was 508 ng/L. A hydrodynamic cavitation device was designed using the orifice plate with nine circular holes and different pressures (1, 3, 5, 7, 9 bar) were applied. Then the removal ratio of PAHs was determined at the following time intervals 5, 10, 15, 20, 25, and 30 minutes. The results showed that the removal ratio increased with increasing pressure and cavitation time. It was 7 % at (p = 1 bar, t = 5 min) and increased to approximately 100% at p = 7 and 9 bar from t = 25 to 30min. Removal ratio values were very close at (p = 7, 9 bars) at all times. So p = 7 bar and t = 25 min which corresponded to circulation degree (Lc = 20 times), cavitation number (Cv= 0. 35) and cavitational yield = 5.84*10-9 ng/j were found to be the best economic and environmental working parameters. The results highlight the importance of choosing the cavitation operating parameters to obtain maximum efficiency in removing PAHs from lakes water.