Collected from Arges river, coming through a water aqueduct, the raw water arrives at Rosu, a 40 years old Drinking Water Treatment Plant.

In order to comply with both the EU and Romanian standards, Veolia Water Solutions & Technologies Romania conceived and constructed for Apa Nova Bucharest several modern installations for the coagulation-flocculation-sedimentation process.

The up-grading of existing plant was accomplished between 2003-2005. It consisted in the execution of five chemical units for reagents (preparation, storing and dosing) to attend the six suspension settlers. The reagents are used as adjuvant for the coagulation/flocculation process and also to correct the water pH.

The two groups of three settlers each one, are feed with raw water through two distribution chambers equipped with overflows and mixers with double propeller. Those insure a rapid mixing of the raw water with the reagents

The chemical treatment plant consists of:

• Aluminium sulphate unit;
• Lime preparing/dosing unit;
• Sulphuric acid unit;
• Polymer unit;
• Soda dosing unit;

In order to optimise reagent dosing as well as monitoring of the raw water, a flow measurement system was installed on the raw water pumping station repression ducts.

After commissioning, the treated water quality was highly increased. The records of the monitoring system confirm the substantial improvement of the water parameters as well as a dramatic reduction in reagent consumption.

In the same period, the Filter Station of Rosu DWTP was rehabilitated by replacing the control valves system from the inlet and outlet water circuits and by installing a new air blower station and a PLC control system. Thus, the automatic filter's washing was finally achieved.