Evaluation and comparison of water treatment plants efficiency and clarifiers performance in removing pollutants in water treatment plants of Tehran, Iran

Water treatment is performed using some conventional processes including coagulation, flocculation, sedimentation (clarification), and filtration. Due to the importance of clarification unit in potable water treatment, extensive studies on its advantages and disadvantages elucidate new horizons for evaluation of Accelerator and Pulsator. In this study, four water treatment plants in Tehran were compared with each other in terms of physical and chemical analysis, effluent water from clarifier unit, and effluent of treated water during 6months from June to October 2012. Results showed the average turbidity in all plants is below standard except the plant No. 5. The total organic carbon (TOC) removal efficiency was undesirable in the both clarification systems (Accelator and Pulsator). On the other hand, TOC removal in Pulsator unit was monitored 40% more than that in Accelator unit. The TDS level was increased during the time period; however, the level lied down standard level. Pulsator is more efficient than Accelator in iron removal. The level of effluent iron in Accelator is more than that in Pulsator referring to iron escape from Accelator. Effluent iron in both systems is lower than the standard values. According to the consumption of chemical coagulants and coagulant aids, Accelator system consumes more than that of Pulsator system thus adding to the overall associated costs of the system. Effluent water in pulsator systems offer better quality than Accelator systems. Moreover, Pulsator system showed better resistance against qualitative and quantitative shocks on raw water.