Tallinna Vesi will invest nearly EUR 9 million over the next three years to improve the biological wastewater treatment process. This will increase the efficiency of nitrogen and phosphorus removal from the wastewater treated at Paljassaare Wastewater Treatment Plant, ensuring that the water returned to the environment is of the highest purity. The changes to be made by through this investment are important for maintaining and improving the environmental status of the Baltic Sea with a view to future needs.

The project is part of Tallinna Vesi's investment programme and aims to reconstruct the 12 secondary clarifiers of the biological treatment system at the Paljassaare wastewater treatment plant, which separate activated sludge from wastewater. Each secondary clarifier is 40 metres in diameter and 4 metres deep. According to Timofejev, the reconstruction will improve the continuity of the biological treatment process, increase its optimisation potential and make the system more flexible and stable.

The reconstruction works on secondary clarifiers will include the renovation of the reinforced concrete structures and upgrading of the technological equipment, putting in place new electrical installations, upgrading of the metering systems and adding automatic control functionalities. Throughout the long construction period, the operation of the treatment plant will be arranged in such a way as to ensure that the high performance of the treatment process is guaranteed at all times. The project will be carried out by RVT Ehitus O and O Mapri Ehitus with the due date for completion in 2027.

At the Paljassaare plant, 130,000 m of wastewater is treated every day in three different treatment stages to turn it into effluent that meets all requirements. The final stage of treatment at the Paljassaare wastewater treatment plant includes the bio-filter ? a technology that is the only one of its kind applied in the Baltic States.

Every year, about 650 tons of debris, 240 tons of grit, 12,000 tons of suspended solids, nearly 2,000 tons of nitrogen and about 250 tons of phosphorus are removed from wastewater at the Paljasaare wastewater treatment plant.