SewerageServices
NETWORK
The network includes:
- The 16 km long Central Sewerage Pipeline (CSP) and its extension towards the Municipality of Thermi with a 11 km long central collector.
- Central sewerage – rainwater collectors
- Primary – secondary sewerage pipes
- Overflow guards and gates for the smooth operation of the network during rainfall and non-return valves (flaps) to prevent seawater from entering the network and being led to the Thessaloniki Wastewater Treatment Plant.
Total length of sewerage and combined pipes: about 1,800 km, of which about 35% is combined pipes.
Total length of rainwater pipes: about 315 km.
Pipe overflow guards: 140 pieces
Number of rainwater drains: 25,000 pieces
Number of manholes: 42,000 pieces
Number of manholes: 42,000 pieces
CSP cross-sections 2,000 – 2,400mm and CSP extension from 600 – 1,600mm
Population served: 1,100,000 persons
Area served: 9,000 hectares (ha)
The quantity of waste transported to the Thessaloniki Wastewater Treatment Plant (WWTF), located on the river Echedoros (Gallikos) is on average 155-160,000 m3/day in dry periods.
The quantity of waste transferred to the AINEA Waste Treatment Plant currently amounts to about 8,000 m3/day with a prospect of up to 15,000 m3/day and does not have any overflow guard.
PUMPING STATIONS
60 sewerage pumping stations operate non-stop in the Greater Thessaloniki Area, covering the areas from the Municipal District of Plagiari to the Sindos Industrial Area, allocated as follows:
- City centre – Kalamaria: 11 pumping stations
- Finikas – Thermi: 2 pumping stations
- Western suburbs – Kalochori: 11 pumping stations
- Pefka: 3 pumping stations
- Triandria: 1 pumping station
- Pylea: 1 pumping station
- Sykies: 1 pumping station
- Panorama: 6 pumping stations
- Filyro: 1 pumping station
- Oreokastro – Paleokastro: 4 pumping stations
- Sindos Industrial Area: 2 pumping stations
- Sindos: 2 pumping stations
- Plagiari: 3 pumping stations
- Polichni: 1 pumping station
- Municipality of Thermaikos tourist areas: 11 pumping stations.
165 pump assemblies are installed at those pumping stations, which transport rainwater and wastewater to the central sewerage pipeline via single or, mostly, double, pressure pipes, to ensure the uninterrupted flow of sewage, if a pipe breaks down, in areas where they cannot be removed by means of gravity.
The total quantity of wastewater transported by the pumping stations to the central sewerage pipeline is 90,000 m3 at most, in periods without rainfall.
These 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 led 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 reaches the central sewerage pipeline. In the third case, local wastewater is directed to the pumping station and then pumped and directed to the central sewerage pipeline using discharge pipes.
Pumping stations have electric pumps that 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 remote control and operation systems (SCADA). 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 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.
Wastewater TreatmentServices
In the general plan prepared in the late 1970s, the Greater Thessaloniki Area was divided up into two waste collection zones:
Thessaloniki Wastewater Treatment Plant
Stage I of the works at the Thessaloniki Wastewater Treatment Plant with final budget of approximately € 11 million started in 1983 and was completed in February 1992, when the plant was put into service by the manufacturer. In the interim period (1989-1992), it was necessary to make the necessary changes to individual units in order to achieve a higher (than originally foreseen) treatment rate of part of the city waste water, while the outfall of the treated wastewater changed (due to the protection of the Axios delta) and now ends in the Thermaikos Bay. Since 1992, the Thessaloniki Wastewater Treatment Plant started to treat approximately 40,000m3/day progressively up to 70,000m3/day, at the beginning of operation of Stage II in 2000, with a treatment rate of over 90%.
The Stage II works started in late 1996 with a budget of € 34 million and upon completion at the beginning of 2000 they treated with an output rate of over 95% all domestic waste water of the city of Thessaloniki with a conventional biological water treatment system and simultaneous nitrogen removal. The Thessaloniki Wastewater Treatment Plant receives around 155-160,000 m3/day, but the planning specifications of the plant provide for acceptance of an average wastewater flow of 296,000m3/day and pollutant load BOD5, SS and Nol 80, 76 and 16 ton/day respectively.
At the same time, following the completion of the project around mid-2002 for the reception and pre-treatment of sewage (€ 4.7 million budget), the Thessaloniki Wastewater Treatment Plant can now receive up to about 1.500 m3/day of waste from areas without sewage systems.
The output of the Thessaloniki Wastewater Treatment Plant passes through the twin Sewage Waste Disposal Pipeline, outside Thermaikos Bay. The project with a budget of € 19 million was completed in mid-2001 and extends over 10.5km on land and 2.5km at sea to a depth of 23m.
The wastewater undergoes secondary treatment at the Thessaloniki Wastewater Treatment Plant and has nitrogen removed and the biologically treated wastewater is disposed of in the bay of Thessaloniki.
However, given their very good quality and in the context of handling the anticipated decrease in water sufficiency, at a global and local level, EYATH S.A. is working with the National Agricultural Research Foundation (N.AG.RE.F) and other bodies to explore (using the old twin pipe towards Axios river) whether treated wastewater mixed with Axios water could be used to irrigate crops in areas close to the Thessaloniki Wastewater Treatment Plant, which was applied in previous summers.
Dehydrated Sludge Thermal Drying Unit:
On 16/1/2012, the 15-month trial operation of the Sludge Thermal Drying Unit started under the responsibility for construction and trial operation of the Public Works Special Service of the Ministry of Infrastructure, Transport and Networks. According to the design, at the end of the trial operation on 16-4-2013, EYATH SA undertook the operation and maintenance of the unit (operator), and assigned it to a contractor through a tendering process.
The Dehydrated Sludge Thermal Drying Unit of the Thessaloniki Wastewater Treatment Plant receives all dehydrated sludge produced daily by the Thessaloniki Wastewater Treatment Plant for heat treatment, evaporation of the water in the sludge and production of a final dry product with a solid content of more than 92%.
The product generated daily (up to 22 t/d of dried product of 5-8% humidity versus 160 t/d dehydrated sludge of 80% humidity) has by nature more uses than dehydrated or calcified sludge. More specifically, the dry product is suitable for the following applications:
as a fuel for cement industries, thermoelectric power plants, building materials industries, composting plants, soil remediation, as soil enhancers for non-food crops, as fertiliser admixture for application to crops, etc.
On the basis of the above, the generated dried product is removed daily through contractors through relevant tendering processes (indicatively, the total quantity of dried sludge for 2017 amounted to approximately 6,820 tons).
Thessaloniki Wastewater Treatment Plant – Summary 2017
Capacity of wastewater treatment plant (in units of population equivalent – p.e.)
Organic load capacity (design): 296,000m3/d
(basis of design study, Directive 91/271/EEC)
Population served (design population): 1.333.000
Flow details for the year 2017:
Average daily flow (m3): 156,470
Waste type – quantities (m3/day):
a. Domestic wastewater: 155,840
b. Industrial wastewater: –
c. Septic tank waste: 630
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Annual production of dried sludge: 6,820 tonnes
Volume of treated wastewater for 2017 (m3): 54.481.000
| Annual output quality average 2017 (mg/L) | BOD5 | COD | SS | N-NH4 | Total N | Total P |
| 14,8 | 65,5 | 19,5 | 1,24 | 8,54 | 3,68 |
Thessaloniki’s Tourist Areas Wastewater Treatment Plant (ΑEΝΕΙΑ)
Aeneia Tourist Areas Wastewater Treatment Plant, which was opened in 1997, and in phase I can treat 27,000m3/day. Initially, it only treated small quantities of wastewater from Michaniona and Angelochori using a network of pipes and three pumping stations and mostly greater quantities of wastewater from septic tanks from other areas of the Municipality of Thermaikos, taken to the plant by tanker trucks.
Since 2001, the main sewage pipeline of the tourist areas has been in operation, with eight pumping stations, and the sewage network of the areas of the Municipality of Thermaikos, whose wastewater is led to the Tourist Areas Wastewater Treatment Plant for treatment, while wastewater from the Plagiari area are included.
As of 1-05-2016, the provision of services for the “OPERATION OF THE THESSALONIKI WASTE TREATMENT PLANT AND TOURIST AREAS PUMPING STATIONS (AENEIA)” was the subject of the contract signed on 28/04/2016, pursuant to Decision No. 04/2016 of the EYATH’s Board, with “AKTOR SA” as contractor, for 60 calendar months (expiring on 30/04/2021).
The new ozonification unit for decontaminating treated wastewater before it is disposed of in Thermaikos Bay has been in operation since its turn-key delivery in spring 2017.
AENEIA Wastewater Treatment Plant – Summary 2017
Capacity of wastewater treatment plant (in units of population equivalent – p.e.)
Organic load capacity (design): 87.000m3
(basis of design study, Directive 91/271/EEC)
Population served (connected population): 41.880
Flow details for the year 2017:
Average daily flow (m3): 8,100
Waste type – quantities (m3/day):
a. Domestic wastewater: 7,360
b. Industrial wastewater: –
c. Septic tank waste: 740
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Annual production of dehydrated sludge (tons, approximately: 3,115 tonnes
Volume of treated wastewater for 2017 (m3): 3.032.560
| Annual output quality average 2017 (mg/L) | BOD5 | COD | SS | N-NH4 | Total N | Total P |
| 2,9 | 22,4 | 6,5 | 0,42 | 7,16 | 5,0 |
Waste Treatment Plant in the Thessaloniki Industrial Area
EYATH S.A. became entitled to use the plant in 2003 and receives around 10,000-15,000 m3/day industrial waste from the Thessaloniki Industrial Area.
During 2012, precursor projects were implemented with funding by the ETVA Industrial Area S.A. that will be integrated in the overall upgrade project to improve the operation of the Waste Treatment Plant. Following the completion of the precursor projects, about 70% organic waste removal is achieved.
Under the responsibility of ETVA Industrial Area, an Environmental Impact Assessment was submitted to the Ministry of the Environment, Energy and Climate Change and a new Environmental permit was issued, including the upgrade works and the operating conditions of the Waste Treatment Plant. A request was also submitted to the Region of Central Macedonia and a Technical Reconstruction permit was issued for performing the upgrade works.
The plant is at the stage of completing the technical reconstruction (trial run as of 1 August), which is carried out by ETVA Industrial Area.
Flow details for 2017 (after 1/8):
Average daily flow (m3): 12,381
Annual production of dehydrated sludge (tons, approximately ): 5,423
