Greek city’s waste district uses integrated approach

Thessaloniki, a port city in the Macedonia region of northern Greece, is the second largest city in that nation. The temperature in the summer reaches 40 degrees Celsius (104 degrees Fahrenheit), and the region attracts many overseas and domestic tourists who stay at seaside towns along the coast. The city also attracts business people who hold meetings at venues such as the HELEXPO Centre, which holds exhibitions and conferences year-round.

The responsibility for waste management in Thessaloniki city and the surrounding prefecture (also known as Thessaloniki) belongs to FODSA, an association that is publicly owned and that manages waste for the Association of Local Authorities of the Prefecture of Thessaloniki as well seven nearby prefectures. FODSA manages the treatment of waste for some 2 million residents overall.

Recycling is encouraged

FODSA widely encourage the inhabitants of the region to recycle and to reduce the generation of municipal solid waste (MSW) sent to the landfill. The group has provided blue-colored 1,100-liter (290-gallon) containers for the collection of mixed recyclables, including paper, cardboard, ferrous and nonferrous cans, as well as , aseptic cartons and PET, HDPE and LDPE plastics. The blue containers are in communal collection points, next to similar-sized green containers for non-recyclable MSW.

The City of Thessaloniki collects the mixed recyclables from the blue 1,100-liter containers on behalf of FODSA using a fleet of 16-cubic meter (21-cubic yard) rear-loading collection vehicles made by Hephaestus Stefanou SA. The trucks, mounted onto Mercedes Axor and DAF chassis, are fitted with a bin lift with comb and trunnion arms compliant to standards for emptying the blue 1,100-liter containers

The collection service uses a driver and two workers. The picked up containers are positioned at the rear of the collection trucks by the workers so they can be emptied by the vehicles’ lifting equipment. Once the containers have been emptied, the crew return them to the communal collection point before moving on to the next one.

FODSA also provides blue-colored “igloos” to collect mixed-colored glass bottles and jars. These are spotted near hotels, multi-occupant dwellings, restaurants and night clubs. The City of Thessaloniki provides a tipper truck with a crane fitted behind the cab to empty the igloos regularly. The system is designed to prevent other recyclable materials from the abrasiveness of the glass, which could affect their output quality for re-processors.

Once the dry recyclables have been collected from the blue containers and igloos, the recyclable materials are delivered to a materials recycling facility (MRF) in Sindos in Thessaloniki prefecture. The paper, cardboard, metal cans and the plastics are separated by eddy current separators before being baled for shipment to processors. The mixed-colored glass bottles and jars are delivered to a glass processor, where the glass is separated by color for melting and producing new glass bottles and jars. The reject material from the Sindos facility is baled and taken to the landfill for disposal.

FODSA says it helps the Thessaloniki region move its waste up the waste hierarchy, aiming to comply fully with the Revised Waste Framework Directive (2008/98/EC) to boost recycling rates and provide a closed loop system for recyclable materials, thus contributing to the circular economy.

FODSA also provides collection points at shopping centers, public buildings and offices for the collection of batteries for recycling, helping to comply with the Amended Batteries Directive (2013/56/EU). The collection of waste electronic and electrical equipment (WEEE), such as worn out refrigerators, freezers and TVs, also is provided, helping the region comply with the WEEE Directive (2012/19/EU).

Putting MSW in its place

FODSA has organized a network of waste transfer stations for the discharge of non-recyclable waste by the municipalities in the prefecture. The transfer stations are designed and sited to help reduce the carbon footprint of waste collection vehicles by not having them travel long distances to the landfill.

The prefecture’s main Finikas waste transfer station processes all the city’s waste. Built in 1995 in conjunction with Netherlands-based Kiggen and Austria-based MUT, the facility is covered and sound-insulated and has four static compactors that compress delivered waste into hermetically sealed rolloff containers. Vehicles discharge their loads into the four static compactors on the facility’s upper level while the lower level is where the rolloff containers receive MSW falling from the top level into the hopper of the static compactors.

When waste collection vehicles arrive at Finikas, their loads are weighed and the vehicles are directed to one of the four static compactor apertures to discharge. A traffic light system is operated: green informs drivers they can reverse inside the waste transfer station to discharge the load; red informs them if they cannot discharge their loads because the rolloff container receiving the waste at the lower level of the transfer station is either full or in the process of being exchanged with an empty container.

The rolloff containers are moved on a traverse moving frame at the lower level. Once a rolloff container is full, it is moved to the right, so an empty container from the left can be moved across to the aperture and locked into place for the fresh loading of waste to continue.

Initially, the waste transfer station only processed waste produced by the City of Thessaloniki, and the staff who manage and operate it are directly employed by Thessaloniki City. However, more recently the City of Thessaloniki has come to an agreement with other municipalities for them to deliver their waste in their own vehicles to Finikas, thus helping them reduce their carbon footprint by not having to deliver the MSW directly to the more distant landfill site.

Finikas is open 24 hours a day, 365 days a year, and the waste from the other cities arrives at non-peak times.

FODSA also has organized waste transfer stations in other parts of the prefecture. FODSA operates a fleet of Renault Kerax and Iveco Trakker trucks that position empty transfer trailers under the loading apertures at these transfer stations to enable loading to continue without interruptions. The group also transports the full ejector trailers to the sanitary landfill site of Thessaloniki Prefecture to be emptied.

A landfill that can last

All non-recyclable waste in Thessaloniki Prefecture eventually is delivered to the Mavrorahi sanitary landfill site. The landfill site is operated by FODSA, which designed and constructed it to replace a former sanitary landfill site at Tagaredes that closed in 2007 after it had reached its full capacity.

Before the new Mavrorahi landfill site opened in 2008, civil works were undertaken, including a specially engineered road complete with a bridge for the waste collection and waste transfer vehicles to travel across a ravine to reach the landfill site. A special road network in and out of the landfill site (for example, one road for incoming vehicles and one road for outgoing vehicles that have been emptied at the landfill) also was constructed. Two scales were installed, one to weigh incoming vehicles and one to weigh the outgoing vehicles so their tare weights could be established. The landfill was lined and the necessary pipework was constructed for the transport of leachate and methane gas out of the landfill site.

To make sure the waste collection and transfer system was not inconvenienced, FODSA allocated an area outside the landfill for Thessaloniki City to deliver fully loaded rolloff containers of waste to the landfill at night and on weekends in the afternoon. Thessaloniki City provides several dedicated rolloff vehicles to empty fully loaded containers inside Mavrorahi in daylight hours, once the landfill site is open.

Empty rolloff containers also are stored outside the landfill so rolloff trucks delivering full containers of waste from Thessaloniki city to Mavrorahi on a 24-hour cycle can offload full containers and reload with empty rolloffs to take back to Finikas. This helps ensure the waste transfer station always has empty containers and the waste collection and waste transfer activity at Finikas is uninterrupted.

Once waste collection and transfer vehicles have been weighed on the first weighbridge at Mavrorahi, they travel along the haul road to the tip face of the landfill to discharge their loads. The waste collection and transfer vehicles head to the second weighbridge at the exit of the landfill to obtain their weighbridge ticket before leaving the site.

The fresh waste deposited at the tip face of the landfill is pushed into the landfill cell by bulldozers for compaction by a landfill compactor made by United States-based Caterpillar Inc. Bulldozers also spread soil excavated from near the landfill over the fresh waste so it is covered to prevent seagulls and vermin from ferreting in the waste and spreading disease.

The leachate collected from inside the landfill is treated in an adjacent desalination plant. The desalination plant uses reverse osmosis technology and polishes the leachate to reduce the levels of biochemical oxygen demand (BOD), chemical oxygen demand (COD) and ammoniacal nitrogen in the leachate before it is discharged offsite.

Methane is flared offsite using a series of flare torches for the different landfill cells. The landfill site complies fully with the requirements of the EU Landfill Directive (1999/31/EC), according to FODSA.

Considering conversion

The current president of FODSA, Michalis Geranis, says he realizes Thessaloniki Prefecture cannot rely on landfills as a long-term solution for handling non-recyclable waste. Thus, he says, FODSA is looking at energy from waste as a longer term sustainable solution to the problem.

FODSA says it is technology neutral and is considering both mass burn systems as well as emerging technologies such as gasification and pyrolysis. It is FODSA’S belief that by incorporating energy from waste into its longer-term waste management strategy, the prefecture will be self-sufficient in its own electricity needs. Facilities also have the option of being tied into a combined heat and power system and qualifying as an R1 type energy-from-waste plant.

Geranis says FODSA is focused on providing sustainable recycling, waste transfer and sanitary landfill services for all of Thessaloniki Prefecture (including landfill rehabilitation at closed landfill sites such as Tagaredes).

The group’s plans include further developing its waste transfer infrastructure via the construction of another waste transfer station, which will help reduce the carbon footprint and emissions from vehicles. Its plans for an energy-from-waste facility will help the prefecture provide renewable energy and become energy self-sufficient for decades, says Geranis.