EYDAP, always a pioneer in environmental protection, has designed and implemented a high - technology  sewage treatment system in Metamorfosi Attikis and Psyttalia island.

The Metamorfosis Wastewater Treatment Plant  (WWTP) has been in operation since1986.  It is the only plant in Attica Prefecture that can receive and treat septic sewage generated from areas without sewerage system. As a result, environmental protection of surface and ground waters was achieved. The design capacity of the plant is 24,000 m3 per day of septic sewage and 20,000 m3  per day of municipal wastewater . With the full processing of wastewater, the produced water is free from the polluting load at a rate of 90%-95% and ends in the Saronic sea completely harmless for the balance of the marine ecosystem.

The Psyttalia Wastewater Treatment Plant (WWTP) has been in operation since 1994 and is now in full operation. The wastewater treatment in Psyttalia includes pre-treatment,   primary and secondary treatment with advanced biological nitrogen removal, sludge treatment and cogeneration of electrical and thermal energy.

The Psyttalia WWT capacity is 5,600,000 p.e., being one of the biggest WWTPs in Europe and worldwide. The average supply of incoming wastewater is the range of 730, 000  m3 per day.

The First Phase of the project has been in operation since 1994, the Second Phase since 2004, while the Third and final phase of works completed in 2007 with the construction of sludge thermal drying unit.

How is  wastewater treated in Psyttalia WWTP?

  • Pre-treatment process starts  at Akrokeramos, with removal of heavy solids, gridding, removal of sand and deodorizing.
  • The pretreated sewage is transferred with submerged pipelines in Psyttalia.
  • Primary sedimentation tanks collect the primary sludge.
  • Advanced secondary biological treatment with activated sludge system achieves removal of organic load and significant reduction of nitrogen.
  • Digestion, dehydration and thermal drying of sludge are the stage of the wastewater treatment.

The processed outflow of WWTP is diffused through pipelines in the Saronic Gulf with reduced organic load of wastewater at a rate of 93% and nitrogen by 80%.

The Thriasio Pedio Wastewater Treatment Center (KELTH) has been operating since 2012 and treats the wastewater of the wider area which is the areas: Aspropyrgos, Elefsina, Mandra and Magoula as well as the surrounding industrial and craft areas. With this project, EYDAP contributes to the upgrading of the environment in the area of ​​Thriasio Pedio and to the gradual consolidation of the Gulf of Elefsina. The installation has a processing capacity (in the first phase) of 21,000 cubic meters of wastewater per day.

How is the wastewater treated at KEL Thriasiou?

The stages of wastewater treatment at KEL Thriasiou in order are:

·         The pretreatment (grading, evaporation) to remove solids and sand.

·         The primary sediment where the primary sludge is separated and collected.

·         Biological treatment with the method of activated sludge (nitrification, biological removal of nitrogen and phosphorus), with the possibility of enhancing the removal of phosphorus by the addition of chemicals.

·         The digestion and dehydration of the total produced sludge which is then transferred for thermal drying to KEL Psyttalia.

·         The refining in sand filters for final filtration of treated wastewater.

·         And finally the disinfection of the treated wastewater before its disposal in the sea, through a submarine pipeline, with the removal of their pollutant load at a rate of over 95%.

Design and Implementation of new Wastewater Treatment Centers in Thriasio Pedio and Eastern Attica.

EYDAP, expanding its activities in Thriasio Pedio, completed the construction of the project "Basic Collectors and Wastewater Treatment and Disposal Facilities in Thriasio Pedio", which includes the construction of about 30 km of sewage collectors in the areas of Thriasio and the construction of WTC in this sensitive area.The project was co-financed by 45% from the Cohesion Fund, by 15% from national resources and by 40% from EYDAP. At the same time, the pipelines of the secondary sewerage network in the above areas were constructed by the Region.

The project is currently in operation. The percentage of serviced residents is constantly increasing, as the Municipalities are constructing real estate connections to the network, while at the same time real estate connections are being constructed by EYDAP through two contracts that are in progress.The drainage, treatment and disposal projects of Thriasio Pedio serve the residential centers: Aspropyrgos, Elefsina, Mandra and Magoula of West Attica (Municipalities: Aspropyrgos, Elefsina and Mandra-Eidyllia), as well as the industrial and bio-industrial areas.

The above projects were carried out with the aim of upgrading the environment, the gradual rehabilitation of the Gulf of Elefsina and the restoration of the balance of the ecosystem in the sea of ​​Elefsina, the improvement of the quality of life of the inhabitants and the protection of public health, the contribution to sustainability in general development of the area. With the completion of the projects, one of the strategic goals of EYDAP for the integrated wastewater management of Attica was implemented.