Provision of sewage and sludge treatment for Athens

Phase A of the Psyttalia WwTP, providing preliminary and primary treatment for the wastewater of the 3.3 million inhabitants and the industries of the Athens greater area was commissioned in mid 1994. Treated effluent is discharged at 65 m depth in the Saronikos Gulf, via a long twin outfall. A new EUR 140 million contract was signed in December 1998 for the expansion of the treatment plant (Phase B), to include biological treatment (carbon removal, nitrification, partial denitrification) of the wastewater as well as treatment of the sludge produced (thickening, anaerobic digestion, dewatering). Effluent quality shall conform with the EU urban wastewater treatment Directive (91/271/EEC). It is expected that the new Phase B works shall be commissioned in early 2002. Several options for the utilisation and disposal of the produced sludge are currently evaluated, including thermal drying and use in cement factories and power plants, co-composting with municipal refuse, etc.