With mounting urgency over the need to comply with European directives relating to waste management as well as to provide a better quality of life for its citizen, in June 2015, a PPP contract was awarded for the construction and operation of an Integrated Waste Management System (IWMS) in the Greek region of Western Macedonia.
Following a competitive tender process, the publicly owned company, DIADYMA, awarded a 25-year contract to design, build and operate the plant to E.P.A.DY.M. – a joint venture formed of waste management and construction firms HELECTOR and AKTOR Concessions. DIADYMA was founded in 1996 to serve waste management needs of Western Macedonia’s 61 municipalities and 300,000 residents. Its shareholders include the municipalities of Grevena, Kastoria, Florina, Kozani & Ptolemaida and Local Unions.
The project included the construction of the IWMS, which includes a Mechanical Biological Treatment (MBT) plant, residual sanitary landfill, Waste Water Treatment Plant (WWTP), as well as auxiliary projects such as weigh bridges, a washing facility, a workshop, office buildings, a service station, a fuel station, a laboratory and a new waste transfer station in Kozani. It also included the operation of existing facilities including nine waste transfer stations.
Following a two-year construction and testing period, on 9 June last year, HELECTOR opened the plant on time. The opening ceremony was attended by George Stathakis, Minister for the Environment and Energy, who inaugurated the facility, as well as representatives of local government and solid municipal waste management bodies from across Greece.
HELECTOR “took the risk, provided the technology and outlined the terms on which the entire PPP arrangement was carried out, closely monitored by our ministry in collaboration with the Ministry of Economy, which was reflected in the contractual terms,” explains Stathakis.
The IWMS receives around 120,000 tonnes of municipal waste each year via 10 regional waste transfer stations. Trucks arriving at the facility are weighed on a weighbridge which records incoming waste and then proceed to the reception unit. Once tipped into the reception bunker, a crane is used to feed a moving floor which in turn feeds the material to a pre-treatment unit where a manual sorting process occurs.
“At the beginning of the line we have some bag openers,” explains Fanis Tsilionis, Director of the Engineering at HELECTOR. “Then we have two screens – a drum screen and a vibrating screen - to separate three different fractions depending on the size of the material.
The fine stream is sent to the composting facility while the intermediate and large fractions are sent for further sorting. First a pair of TOMRA optical sorters identify plastic materials suitable for recycling. The next pair removes paper from the stream. A ballistics separator is also used to sort plastics based on their shape, with films separated from 3D plastics such as bottles. A further pair of optical sorters separate 2D plastic films into two streams – transparent and coloured.
“The plant recovers five different types of plastics – transparent film and mixed coloured film, PET, HDPE and PP. We also recover paper and card, and ferrous and non-ferrous metals. Residual, non-recyclable waste is disposed of at an adjacent sanitary landfill. The remaining material, with the paper and plastics removed, passes over band magnetic separators for ferrous recovery and eddy current separators for the recovery of aluminium cans,” says Tsilionis.
The recovered materials are baled prior to sale. The plant operates six days per week on two shifts and all the maintenance takes part in the downtime.
The project also includes a Centre for Environmental Awareness to provide information to the public about the operation of the plant and raise awareness on issues of waste management and sustainable development.
The organic fraction is diverted to the composting facility for biological decomposition in enclosed horizontal aerobic bioreactors. Back in 2005, the firm acquired German technology developer Herhof and its composting technology, which significantly improves the mechanical stability of the material.
“We produce a Compost Like Output (CLO),” explains Tsilionis. “We could produce a Solid Recovered Fuel (SRF), but the plant is located in a major lignite mining centre where the CLO can be used for restoration purposes. We have a contract with the Public Power Corporation of Greece which gives us an offtake option for all the materials we’re going to produce for the next 25 years.”
According to Herhof, its computerised system processes organic waste into a hygienically sound product. Organic material is aerated for approximately two weeks in composting bins with regulated temperature, ventilation and humidity. In order to ensure a hygienic output, the composted material is heated up to 65°C. In addition, odours and groundwater pollution are managed within the closed system.
The semi-stabilised material produced is then transferred to a maturation shed where it remains for 4 to 6 weeks and is turned using a windrow turner as required by temperature, humidity and oxygen content. Following this period, the now stabilised material is sent to a refinery unit where the organic material is separated from any residual materials such as hard plastics, gravel, films and other inert wastes. The end result is a Type A compost which is considered to be fully refined and meets Greek legislation.
The plant is currently diverting some 80% by weight of biodegradable wastes from landfill and achieving a recovery rate of recyclables of 35% by weight of the quantity of recyclable materials entering the SWTP.
Navigating Financial Headwinds
According to Tsilionis, the project was a breakthrough: “It was the first PPP in waste management. Of course it was a challenge. It was the first robust project with backing from the European Investment Bank. The process requirements are quite challenging. It was a big challenge, and a big success. Also bear in mind that financial closure took place on the 10th of June 2015, at the peak of Greece’s financial turmoil with a lot of pressure from lenders and the European Commission.”
“We signed the deal and 20 days later capital controls were imposed, so we had to undertake the project in a capital controlled environment while having to acquire equipment from abroad. Nevertheless, we managed to bypass the problem and deliver the project within two years. We’re very proud to have made such an achievement,” he adds.
While not currently implemented, the new national waste management plan (NWMP), is expected to see additional measures such as the separate collection of organic wastes come into force. This will result in the availability of additional waste streams. Because of this, to future proof the plant, HELECTOR says that the biological treatment and the mechanical sorting technologies are designed be compatible with these additional waste streams.
The plant currently receives mixed municipal waste. However, the firm is discussing with the public authority the option of processing pre-sorted organics, as well as other types of pre-sorted materials such as mixed plastics which they can handle with the mechanical separation unit operating as a kind of MRF operation.
With the implementation of the NWMP, Tsilionis believes there is potential in Greece for significant additional waste infrastructure, and that Kozani’s MBT provides an ideal model for financing those projects. Time will tell. Watch this space…
A video explaining the plant’s processes can be viewed below