In the general plan prepared in the late 1970s, the Greater Thessaloniki Area was divided up into two waste collection zones:
a. the central and western waste collection zone, where most of the urban and industrial activities are located, from which waste is collected and transported to the Thessaloniki Wastewater Treatment Facility in the Sindos area.
b. the eastern waste collection zone comprised of tourist areas, from which waste is collected and transported to the Aeneia area of the Mun. of Michaniona.
c. waste from the Thessaloniki Industrial Area is collected and treated at the Waste Treatment Plant which EYATH S.A. became entitled to use from January 2003 onwards.
EYATH S.A. operates and maintains two waste treatment facilities in the Greater Thessaloniki Area. It oversees the Thessaloniki Wastewater Treatment Facility in Sindos located next to the Gallikos River and the Aeneia Waste - Sewerage Treatment Facility in the Angelochori area which handles waste from tourist areas.
The Thessaloniki Wastewater Treatment Facility receives the majority of urban wastewater from the city of Thessaloniki via the central sewerage pipe and every day also receives tanker trucks from remote areas which are not connected to the city’s sewerage network. Under current operating conditions, the facility treats 160,000 m3 of wastewater a day, and handles around 120 tanker trucks a day on average.
Stage I of the works on the Thessaloniki Wastewater Treatment Facility with a budget of 3.5 billion GRD started in 1983 and was completed in 1989. Stage II to extend the Thessaloniki Wastewater Treatment Facility commenced in October 1995 with a budget of 11.3 billion GRD. The cost of Stage II and of the disposal pipeline (another € 70 million) was co-financed by the Cohesion Fund (85%) and the Public Investments Programme of the Ministry for the Environment, Physical Planning and Public Works (15%). The facility was put into service by the contractor in May 1992. The Thessaloniki Wastewater Treatment Facility was handed over to EYATH S.A. on 1.5.2002. Wastewater undergoes secondary treatment at the Thessaloniki Wastewater Treatment Facility and also has nitrogen removed.
Biologically treated wastewater is then disposed of into gulf of Thessaloniki. Due to the very high quality of the treated water, and concerns about reductions in water resources of the area in the future, EYATH S.A. is working with the National Agricultural Research Foundation (N.AG.RE.F) and other bodies to explore whether treated wastewater could be used to irrigate crops in areas close to the Thessaloniki Wastewater Treatment Facility. Research is also being carried out about disposal of treated wastewater after additional treatment by passing the water through various films in order to enable that treated water to top up the subterranean aquifer.
For the time being the ‘Aeneia’ Facility receives part of the urban wastewater from the Municipalities of Thermaikos and Nea Michaniona and a large number of tanker trucks every day. Once the sewerage network is completed it will cover all tourist areas in the region. The facility was opened in 1997 and in phase I can treat 29,000 m3 a day. Initially it only treated small quantities of wastewater from Michaniona and Angelochori using a network of pipes and three pumping stations, but most wastewater came from septic tanks and was taken to the facility by tanker trucks. Today a central sewerage pipe has been installed in the tourist areas, there are 8 new pumping stations and a sewerage network in those sections of the Municipality of Thermaikos located after the Thessaloniki – Michaniona Road, whose wastewater is all directed to the Aeneia facility to be treated.
The Aeneia Facility currently offers secondary biological treatment and nitrogen stripping for 2,500 m3 of septic tank waste and 5,000 m3 of urban wastewater a day on average, producing exceptionally good results. Since 2006 a total of 2,650,000 m3 of wastewater have been treated and 46,355 tanker trucks unloaded at the facility.
The Waste Treatment Plant in the Thessaloniki Industrial Area became available to EYATH in 2003 and offers biological treatment for between 10,000 and 15,000 m3 of industrial waste a day. During 2004 the service agreement for running and maintaining the Plant covering the period 1.1.2003 to 30.11.2004 expired. The Plant now needs to be further repaired and extended to ensure problem-free operations.
Treated wastewater from the Thessaloniki Wastewater Treatment Facility and the Aeneia Facility is disposed of in the Thermaikos Bay via submerged pipes. The treated water released in this manner complies with all environmental terms and conditions and relevant legal provisions.
EYATH S.A.’s goal is to ensure that all wastewater from the Greater Thessaloniki Area is collected and optimally treated (while also stripping nutrients from the water) and the company ensures that it monitors the quality and environmental performance of its works.
The fact that the Thermaikos Bay has been declared a ‘sensitive body of water’ which is the home to numerous activities in the area requires the company to take special measures to protect it, to ensure compliance with Directive 91/271/EEC.
That’s why EYATH S.A., in partnership with other governmental and research bodies, has been consistently striving to build new projects, improve and extend existing facilities, introduce new technologies and take all measures needed to safeguard Thermaikos Bay.
Sewerage collection/drainage in the Greater Thessaloniki Area is provided by a network of rainwater and sewerage pipes. Rainwater pipes direct the water to the sea while sewerage pipes feed into the central sewerage pipeline and direct the waste towards the Thessaloniki Wastewater Treatment Facility at Sindos, in the sea area close to the Gallikos River, where the wastewater undergoes biological treatment.
Thessaloniki’s sewerage network is a separated network apart from the central area where the network is a combined one.
35 sewerage pumping stations operate non-stop in the Greater Thessaloniki Area covering all suburbs from Finikas and Thermi to the Sindos Industrial Area. Below is a list of pumping stations by area:
103 pump arrays are installed at those pumping stations. They transport rain water and wastewater to the central sewerage pipeline via a pair of pressure pipes, to ensure the uninterrupted flow of sewage (if a pipe breaks down) in areas where gravity does not operate.
The total quantity of wastewater transported by the pumping stations to the central sewerage pipeline is around 90,000 m3, in periods without rainfall.
The pumping stations remove sewerage from the areas listed above by working in teams or in a chain layout or on their own. In the first case the wastewater from some local pumping stations is forwarded to a central pumping station which directs it on to the central sewerage pipeline. In the second case, wastewater is pumped from one pumping station to the next using twin discharge pipes till it gets to the central sewerage pipeline. In the third case, wastewater is directed to the pumping station and then pumped and directed to the central sewerage pipeline using twin discharge pipes.
Pumping stations have electric pumps which operate automatically, coming on and switching off based on electronic sensors that detect sewerage levels in line with the preset levels. Operations are controlled via two cutting-edge remote control and operation systems. Those systems operate using programmable logic controllers (PLCs) at the local pumping stations which control the entire process. All automated pumping station systems are wirelessly connected to the control centre which receives all information needed for surveillance purposes. The control centre has two computers fitted with suitable hardware (transceivers, modems, antennas, etc.) and software to control operations and handle faults, and ensure remote control to enable the pumping stations to operate without interruption round the clock. Necessary preventative or emergency cleaning work is carried out to maintain the pumping stations.
The control centre is located at Megalou Alexandrou St. The sewerage pumping stations operations, maintenance and repair crews are also based at the same premises.