EDSNA provides a sustainable waste management system for Attica

Written by: Timothy Byrne | Published:

Timothy Byrne, waste collection specialist in mediterranean countries, looks at how solid waste management authority, EDSNA, ensures the waste management system in the Greek prefecture of Attica is a sustainable one.

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

EDSNA is the solid waste management authority responsible for waste management for the entire region of Attica. This includes the responsibility for managing waste produced from Athens each year as well as that produced by the other 66 municipalities making up Attica Prefecture. To manage these large volumes of waste, 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. It accepts waste on a 24 hour basis. 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, the 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. Once the load is discharged, the vehicles return to the weighbridge so that their tare weights can be established before leaving site.

Waste is transferred from the bunkers by 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. The fully loaded containers are lifted from the aperture of the compactors by a Mercedes SK 8x4 Kaoussis Multilift HL32.56 hook loader and placed in the container storage compound. In the container compound a Scania 8x4 Kaoussis Multilift LHT320.56 hook loader loads the full roll on/off containers for transport to the Fyli sanitary landfill site. The Scania hook loader vehicles are weighed before leaving the transfer station so that their net weight of municipal waste in their roll on/off containers 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 roll on/off containers. These leachates are collected in a tank and are 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 six thousand tonnes of municipal waste a day collected across Attica. It accepts 1.8 million tonnes of municipal waste a year. Fyli is not only the largest sanitary landfill site operated in Greece, but it is also the largest sanitary landfill site in Europe.

Waste is delivered either directly by municipalities in waste collection vehicles, or by using waste transfer vehicles, either coming from the Schistou waste transfer station or from waste transfer stations operated by the municipalities around the periphery of Attica.

The facility is open from 6am morning until 7pm. 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. The landfill also receives 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. Once empty, the collection vehicles return to a series of weighbridges so that their tare weights can be established before leaving the site. Bulldozers and landfill compactors compress the freshly deposited waste into the landfill cell. 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. The heavies fall to the bottom of the tank from a suspension while flocculation is achieved with the light fraction remaining on the top of the water after coming out of suspension with the heavy fraction. The leachate is further treated to reduce its BOD, COD and ammoniacal nitrogen content before being discharged off site 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 currently being engineered for landfill operations. Phase two will start operations within the next year.

Mechanical biological treatment and recycling plant

EDSNA has also constructed a mechanical biological treatment and recycling plant at Ano Liosia next to its sanitary landfill. The plant, which commenced operations in 2010, processes 1200 tonnes of waste a day equating to 600,000 tonnes of municipal and recyclable wastes a year. It is one of the largest in Europe. The facility is open 24 hours a day so provides provision for the discharge of waste by municipalities’ waste collection vehicles both day and night.

On arrival, waste collection vehicles are weighed and pass through a radiation detector. The vehicles proceed to the tipping platform where they discharge their loads into a waste storage bunker. Once empty, the vehicles return to the weighbridge so that their tare weights are recorded before leaving site.

The facility has a number of waste storage bunkers split by partitions. Some waste storage bunkers receive raw municipal waste while the others receive commingled recyclables collected from the blue coloured 1100 litre waste containers. These EDSNA has provided to the municipalities across Attica for residents to use for their recyclables.

Waste inside the waste storage bunkers are transferred to a network of conveyor belts by overhead gantry cranes with cactus grabs. The waste is processed using manual and mechanical techniques. The recyclable commodities are extracted e.g. glass, paper, cardboard, plastics e.g. HDPE, TetraPak and LDPE as well as ferrous and non-ferrous cans. These materials are baled ready for exporting to processors. 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) which are disposed of inside the sanitary landfill site.

Hospital waste incinerator

A hospital waste incinerator capable of incinerating 30 tonnes of waste a day is also situated at Ano Liosia near to both the sanitary landfill site and the mechanical biological treatment and recycling plant. The incinerator has been in operation since 2002 and receives hospital waste from across Attica, the whole of the Greek mainland as well as its islands. Combustion is achieved using the proven rotary kiln type incineration process. The plant complies fully with Industrial Emissions Directive (2010/75/EU). The incinerator bottom ash (IBA) and the air pollution control residues (APCR), the plant’s outputs, are sent to authorised treatment facilities for safe disposal

Recycling and education

EDSNA promotes recycling to the community in schools and to the wider population across Attica. Containers for the collection of paper and cardboard were recently rolled out to schools to increase the amounts of paper and cardboard recycled. EDSNA has also provided the blue coloured 1100 litre containers for the deposit of plastics, paper and cardboard, and blue coloured igloos for the deposit of commingled glass. These containers are placed at communal collection points next to the green coloured 1100 litre containers for non-recyclable waste throughout Attica.

The containers are emptied using vehicles operated directly by the municipalities. In some areas of Athens, EDSNA also provides 1100 litre containers specifically for the collection of paper and cardboard. These are emptied by EDNSA’s own collection vehicles. The collection of small batteries is also widely encouraged. The company also provides shredding plant to Attica municipalities for the shredding of green waste. The output can be turned into compost which moves it up the waste hierarchy as well as diverting it from sanitary landfill.

The future of waste treatment in Attica

EDSNA have drawn up future plans to push waste further up the waste hierarchy and move away from the use of sanitary landfills for the treatment of municipal waste. In the future, the existing mechanical biological treatment 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 mechanical biological treatment plants will be built around the periphery of Attica. This will help to treat waste nearer to where it is produced, thus reducing the carbon footprint. The objective of this is to recover as many recyclable materials from the waste stream as possible, leaving only a minimal fraction which cannot be recovered being 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 also continue to carry out environmental monitoring and rehabilitation of closed landfill sites so that the volumes of leachate and methane can be stabilised. Once the volumes of leachate and methane have been reduced, the land will be available for an alternative use such as it being turned into a park, nature reserve etc.

In conclusion, EDSNA provides sustainable waste management systems for Attica Prefecture and will continue to do so in the future. EDSNA will achieve this through education in schools and to the wider population to encourage recycling to help increase landfill diversion and push waste further up the waste hierarchy. The company will also implement alternative methods of waste treatment to recover as many recyclable materials remaining in the residual waste stream as possible.

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