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“Opinion” EDSNA Provides a Sustainable Waste Management System for Attica


 

Attica Prefecture includes the capital of Greece, Athens, and has a population of 3.8 million people; sustainable waste management systems are important to manage the 2.1 million tonnes of municipal waste generated annually.

EDSNA is the solid waste management authority responsible for managing waste produced from Athens and the other sixty-six municipalities making up Attica Prefecture. To manage these large volumes, EDSNA has built and operates a network of waste management facilities.

Waste Transfer Station

The Schistou waste transfer station, constructed in 1991 and located near Piraeus, processes 900 tonnes of municipal waste daily and is operational 24 hours. Municipalities from the surrounding area deliver waste in conventional waste collection vehicles to the waste transfer station. The island of Salimina also delivers waste to the Schistou waste transfer plant, via a ferry to Piraeus. The waste is then driven the short distance to the plant.

Upon arrival, waste collection vehicles are weighed and pass through a radiation detector. They proceed to one of two tipping platforms where they discharge their loads into a waste storage bunker before returning to the weighbridge so their tare weights can be established before leaving site.

Waste is transferred from the bunkers using two steel buckets, pulled by wire cables, into the apertures of four Marrel static compactors. Each compactor feeds waste into closed 30 cubic metre roll-on-off containers, which, once loaded, are lifted from the by a Mercedes SK 8×4 Kaoussis Multilift HL32.56 hook loader and placed in the container storage compound. There, a Scania 8×4 Kaoussis Multilift LHT320.56 hook loader loads the containers for transport to the Fyli sanitary landfill site. The Scania hook loader vehicles are weighed before leaving the transfer station their net container weight is recorded.

The waste transfer station complies with all environmental regulations. It has a water spray system to reduce dust produced in the tipping areas. A drainage system extracts any leachate produced by the static compactors when compressing the waste into the enclosed containers. These leachates are collected in a tank and treated on site to reduce their BOD, COD, and ammoniacal nitrogen levels. The cleaned water is discharged into the sewer system.

Sanitary Landfill Site

The Fyli sanitary landfill site at Ano Liosia disposes of 6,000 tonnes of municipal waste a day collected across Attica. It accepts 1.8 million tonnes of municipal waste a year. Fyli is the largest sanitary landfill site operated in Greece and in Europe.

Waste is delivered directly by municipalities in collection vehicles, or by waste transfer vehicles coming from Schistou or other waste transfer stations around the periphery of Attica. Upon arrival, all waste is weighed at a series of weighbridges. The waste collection vehicles also pass through a radiation detector. The landfill receives all waste coded ‘20’ in the European Waste Catalogue e.g. 20 03 01, 20 03 02, and 20 03 03; and, waste coded ‘19’ e.g. 19 12 10 and 19 12 12 waste transfer station / pre – treatment outputs. Once the waste collection vehicles have been weighed, they drive along the haul road to the tip face of the landfill where they discharge their loads. Next, they return to a series of weighbridges so that their tare weights can be established before leaving the site. Landfill compactors compress the freshly deposited waste into the landfill cell, and bulldozers cover the waste with soil to prevent vermin from feeding on it.

The landfill site complies fully with the requirements of the EU Landfill Directive (1999/31/EC). It is lined and collects leachate, which is treated in a desalination plant on site using the reverse osmosis system. The fresh leachate entering the treatment plant is received in a settling tank. Theheavies fall to the bottom of the tank from a suspension while flocculation is achieved with the light fraction remaining on the top. The leachate is further treated to reduce its BOD, COD, and ammoniacal nitrogen content before being discharged into the sewer network.

Methane is burnt on site using a series of flare torches. Electricity is harnessed from the burnt methane through a series of energy generator sets.

The landfill is split into two phases. Phase one is currently being filled while phase two is being engineered for landfill operations. Phase two will commence operations within the next year.

Mechanical Biological Treatment and Recycling Plant

EDSNA has also constructed a mechanical biological treatment (MBT) and recycling plant at Ano Liosia next to its sanitary landfill. The plant processes 1,200 tonnes of waste a day equating to 600,000 tonnes of municipal and recyclable wastes a year. On arrival, waste collection vehicles are weighed and pass through a radiation detector. The vehicles proceed to the tipping platform to discharge their loads into a waste storage bunker before returning to the weighbridge so their tare weights are recorded before leaving site.

The facility has a number of waste storage bunkers split by partitions. Some receive raw municipal waste while the others receive commingled recyclables collected from the blue coloured 1,100 litre waste containers EDSNA provides for residential recyclables collection.

Waste inside the waste storage bunkers is transferred to a network of conveyor belts by overhead gantry cranes with cactus grabs where it is processed using manual and mechanical techniques. The recyclable commodities are extracted e.g. glass, paper, cardboard, plastics e.g. HDPE, TETRAPAK, LDPE, and ferrous and non-ferrous cans. The organic waste fraction is mixed with green waste and composted using the open windrow aerobic process. The remaining non-recyclable fractions are converted into a secondary recovered fuel (SRF), and disposed of inside the sanitary landfill site.

Recycling and Education

EDSNA promotes recycling to the wider population across Attica. Containers for the collection of paper and cardboard were recently rolled out to schools to increase diversion rates. EDSNA has also provided the blue coloured 1100 litre containers for the deposit of plastics, paper, and cardboard, and blue coloured igloos for commingled glass. These containers are placed at communal collection points throughout Attica. The collection of small batteries is widely encouraged and the company provides Attica municipalities plants for green waste shredding. The output can be turned into compost.

Future Waste Treatment in Attica

EDSNA plans to move away from sanitary landfills for the treatment of municipal waste. The existing MBT and recycling plant at Ano Liosia will be expanded with an additional capacity of 350,000 tonnes processing capacity per annum. An additional network of five smaller MBT plants will be built around the periphery of Attica. This will help treat waste nearer to where it is produced, reducing the carbon footprint. The objective is to recover as many recyclable materials from the waste stream as possible, leaving a minimal fraction disposed of in locally constructed sanitary landfill cells. Five new sanitary landfill cells will be constructed inside inactive quarries or mines for the deposit of the non-recyclable waste fraction. The output fraction will be easier to manage since there will be very little BOD and ammoniacal nitrogen to treat. The output will be more COD-based, which is more stable to treat. Methane will also be flared off site and electricity harnessed from it through energy generator sets.

The company will continue environmental monitoring and closed-site rehabilitation activities to stabilize leachate and methane.


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