2. Description of the technological process flow

The general characteristics of the wastewater treatment plant (WTP) Calafat and the process flow will be presented. The process flow comprises two stages: the pretreatment (which is the so-called mechanical stage) and the biological stage. Figure 1 presents the general block diagram of the WTP, and Figure 2 shows an aerial photography of the WTP.

The WTP was designed for the treatment of a daily average flow of 8366 m3 /day and of a maximum flow of 530 m3 /h. The WTP size was chosen in order to solve the needs of a number of maximum 29,000 inhabitants of Calafat town, predicted for 2020. The treatment method is a classical one, with a mechanical stage for the impurity removal and a biological stage based on activated sludge. The wastewater enters in a tank; it is lifted with special pumps to the pretreatment area and after that is gravitationally discharged in the biological tanks, where the water is aerated and mixed with the activated sludge. Thus, the biodegradation of the water occurs. Finally, the effluent is discarded through decantation.
