By Timothy Byrne
Monaco may be geographically tiny, but it is a microcosm of European municipal, commercial and industrial waste generation and management. In addition, the warm Mediterranean climate attracts many tourists both staying and visiting the principality from neighbouring coastal resorts. The Formula One Grand Prix, held annually, also adds to visitor numbers with consequent increases in waste production.
To collect waste and recyclables from the principality's homes and businesses privately owned Societe Monegasque D' Assainissement (SMA) operates a small fleet of refuse collection vehicles. For the hotels, casinos, restaurants etc. 660 and 1100 litre capacity containers are provided the for large volumes of food waste and packaging waste produced at the establishments.
SMA, which began providing waste services in Monaco way back in 1938, provides the collection of municipal, commercial and industrial wastes - as well as dry recyclables. Waste Electronic and Electrical Equipment (WEEE) is also collected, as well as hazardous wastes including oil, batteries, gas canisters, paints and solvents.
It is also the responsibility of the SMA to provide street and beach cleansing services which include cleaning the public channels and private alleys, galleries, public elevators, commercial and technical galleries, waterways and car parks, as well as road tunnels and industrial areas.
In addition to the commercial waste and recycling collections, SMA also services communal collection points housing containers of 240, 660 and 1100 litre capacities. In some parts of the Principality, a door to door waste collection system is provided where residents place their waste on the pavement, in plastic bags, for collection.
The collection of municipal and commercial wastes is carried out using a fleet of Provence Bennes rear loading satellite refuse collection vehicles mounted onto Toyota Dyna two axle 7.5 tonne chassis. Larger Geesinknorba GPM Mini, Grange Variopress and Farid T1SM rear loading refuse collection vehicles mounted onto Renault Midlum two axle 12 and 15 tonne chassis, as well as Renault Premium and Iveco Eurocargo two axle 17 tonne chassis are also used. The smaller Provence Bennes 7.5 tonne two axle satellite units and Geesinknorba GPM Mini refuse collection vehicles are used for areas of tight access such as side streets and beaches as well as for villas which do not produce large volumes of waste.
The larger Faun Grange and Farid T1SM two axle waste collection vehicles are used to collect the larger volumes of municipal and commercial wastes produced by hotels, casinos and restaurants etc. Any excess waste placed next to full waste containers is also collected to maintain hygiene and prevent odours produced from decomposing waste in the warm climate.
The waste collection service has a workforce of forty staff who collect waste seven days a week. Two thirds of the waste is collected during the day with the remainder collected at night.
In the Fontvieille district a further development is the use of the pneumatic waste collection system, installed by ENVAC back in the mid-1980s.
Waste from the pneumatic collection system is transported through an underground network of pipes directly into the waste storage bunker of the waste to energy plant at Fontvieille. The system, which uses a vacuum to suck waste from residents into underground containers, is well suited to the densely populated principality.
In addition to increasing collection efficiency, it reduces the need for additional waste storage infrastructure. Waste from the system is transported directly to the principality's incineration plant and discharged into the waste storage bunker.
Underground container collection systems are also used for the commingled collection of dry recyclables including paper and cardboard collected together, while plastics - TETRAPACK, HDPE and PET, drinks cartons, steel and aluminium cans and aerosol cans.
SMA also provides a roll-on-roll-off (RoRo) container service offering portable compactor containers for the collection of large volumes of municipal, commercial and industrial wastes produced by hotels or commerce. The containers can be housed in the basement of the building to be emptied daily or weekly dependent on the fluctuations of waste produced.
The compactors come with their own power pack so the producer can operate the compaction mechanism consisting of a block compactor inside the portable compactor container. They are totally sealed and retain all leachates produced during the 6:1 compaction process. These are collected and emptied by SMA'S Iveco Eurocargo two axle 18 tonne RoRo hook lift container truck, which discharges at a waste to energy plant in Fontvieille.Energy recovery
In the heart of the Fontvieille district, the SMA operates an 80,000 tonne per year waste toenergy plant. Initially, it was built with three identical furnace grates, but now only treats a maximum of around 50,000 tonnes of waste per annum. It achieves this by using two of the three furnace grates continuously and having the third as a standby furnace grate for when one of the other two are shut for annual maintenance.
The history of waste incineration in the Principality stems back to 1898 when the first incineration plant was constructed at Fontvieille. This facility had a batch treatment process and operated until it was replaced in 1938. That facility, located on the same site, also operated a batch process and was closed in 1980.
That year the third waste incineration plant for the principality was constructed, again at the same location at Fontvieille. The plant occupies an area of 1500 m2 which justifies its vertically orientated design. The plant is a continuous operation incinerating municipal, commercial and industrial wastes throughout the year.
When the plant was constructed it was built to be earthquake resistant and the chimney was incorporated into the building so as to be invisible to the human eye. This was important since it is located in the heart of the Fontvieille district and close to the harbour. The white water vapour plume, traditionally produced by waste to energy plants across Europe is heated so as to be totally eliminated.
The plant was upgraded in 1994 to comply with the EC Directive on Air Pollution. The upgrade incorporated a wet scrubbing system to treat the emissions produced by the incineration process prior to discharge from the chimney. In 2006, the incineration process was upgraded again, incorporating the use of the CNIM Lab Selective Catalytic Reduction (SCR) technology to further reduce emissions.
The plant recovers energy from municipal, commercial and industrial wastes in the form of electricity, heat and cooling for use in air conditioning systems.
The electricity generates covers the plant's parasitic load with excess being exported to local utility, Societe Monegasque de I Electricite et du Gaz. Exported electricity supplies the annual public lighting requirements for the whole Principality.
Steam is supplied to a neighbouring heat production and chilled water plant where is used to produce hot and chilled fluids. The hot and chilled water are distributed through two networks, one to supply hot water at 95oC and the cold water at 5oC for the use in air conditioning for public sector offices and public facilities in Fontvieille.
Approximately 70% of the waste entering the incineration plant is municipal waste while 23% is assorted waste from packaging, non – hazardous industrial wastes as well as wastes from parks and open spaces. The facility also receives sewage sludge from the Monaco sewage treatment plant.
The vehicles discharge their loads simultaneously into a 1200 m3 waste storage bunker with a capacity to store two to four days waste.
A shredder has been installed in the tipping hall to shred incoming green and bulky wastes to a suitable size to be incinerated. Once shredded, these are discharged into the waste storage bunker. The tipping hall is under negative pressure to eliminate foul odours produced by the delivery of fresh waste as well as waste stored in the waste storage bunker.
Waste is mixed by two overhead travelling cranes fitted with cactus grabs and placed into the two furnace feed hoppers. Sewage sludge delivered to the plant is pumped directly into the furnace grate using an IC 850 where it is destroyed at 850o degrees.
Energy from the combustion process is recovered in the CNIM boilers at 13.3 tonnes per hour of steam which is then superheated to 300o degrees and 28.5 bar. The steam is cooled on contact with the screens and the various tube assemblies so that, the temperature is reduced to 230o degrees at the outlet of the economiser. The heat exchangers are cleaned regularly using steam operated rotary and harrow type soot removers.
The energy recovered is in three forms: electricity, heat and refrigeration. The electricity is produced through a 2.6 MW back-pressure turbine driven alternator.
Incinerator bottom ash (IBA) constitutes up to 250 kg per tonne of waste incinerated. It is processed through a drum and then cooled and extinguished through an extractor unit. The ash is transported by conveyor where the remaining ferrous and non-ferrous metals are removed by magnet for export to a metal processor.
The remaining bottom ash is transported to a 170 m3 pit while the incinerator bottom ash is collected by a tipper vehicle. It is loaded into the vehicles by an overhead travelling crane with clamshell bucket which lifts the bottom ash out of the 170 m3 storage pit.
The IBA ash is taken to be processed for use in the construction industry, for use in the construction of roads and buildings thus reducing the use of virgin aggregates.Conclusion
By utilising a variety of vehicles and container systems, including underground containers and an automated vacuum collection system, SMA is able to offer a highly efficient collection service in the crowded principality. Altogether it could be said that it's a system fit for a king – or at least a prince.
Timothy Byrne is a MCIWM Chartered Waste Manager and member of ISWA.
Dust removal is carried out using two field electrostatic filters. These enable dust levels of 30 mg/Nm3 to be achieved at the outlet before final treatment. The ash recovered from this process, known as Air Pollution Control Residues (APCR), is the second type of residue produced in an incineration plant equating to 25 kg per tonne of waste. To comply with stringent environmental controls (EC Directive on Air Pollution), an additional dust treatment stage comprising wet scrubbing was introduced in 1994 and then further optimised introducing the CNIM Lab Selective Catalytic Reduction (SCR) technology in 2006. The purpose of these upgrades is to ensure the levels of chlorine, sulphur, and heavy metals (dioxins) are drastically reduced and that there is improved filtration of dust at the electrostatic filter outlet. The system incorporates a wet scrubbing process which involves scrubbing the dioxins in two reactors and a filter agglomeration module used to absorb acidic gases while pollutants are transferred to a milk of lime and soda solution. The solution is purified in a small effluent treatment plant on site.
The treatment plant separates the pollutant materials using precipitation, flocculation and settling. The remaining water is removed using a filter press. The residue left once the water has been extracted is known as filter cake, which is a third by-product of incineration. The extracted water is filtered by being passed through a sand filter and an activated charcoal filter before being discharged off site.
The CNIM Lab Selective Catalytic Reduction (SCR) technology further reduces emissions after the wet scrubbing cleaning process by heating the gases to 250o degrees by burners operated by natural gas. The gases are mixed with ammonia gas, used as a reagent agent. The Catalytic reaction converts the dioxins into nitrogen and water vapour.
The Air Pollution Control Residues, the second constituent of incineration captured by the bag house filter, are driven by endless screws and stored in a silo before being filled into large sealed bags. Due to the hazardous nature of this waste, it is taken to a hazardous landfill site where it is stabilised and solidified to encapsulate its toxic constituents before burial.
The filter cake, the third constituent of incineration extracted from the supplementary Air Pollution Control Residue cleaning process, is also sent to hazardous landfill because its constituents contain chlorine and heavy metals. The filter cake too is stabilised and solidified to encapsulate its toxic constituents on arrival at the landfill site before burial.
After the gases have been cleaned, they are discharged using a horizontal silencer into the atmosphere through the plant's chimney where sampling probes are fitted, connected to an analyser. This provides a continuous measurement of the contaminants discharged into the atmosphere. If the level of contaminants exceeds the specified limits, the command and control system immediately alters the regulation settings.Spotlight Promotion: Underground Automated Waste Collection
Long before its installation throughout the Principality of Monaco, Envac had built a reputation for keeping waste out of sight, and out of mind; two elements that are difficult to achieve in a world where urbanisation is driving continual growth in the amount of waste produced.
As the global pioneer of underground automated waste collection, having invented the technology in 1961, Envac is now recognised as a way in which to maximise shrinking developable land space by simply taking waste underground.
Almost 55 years since its first installation, Envac can be found in over 700 installations worldwide. From residential developments to airports, underground automated waste collection represents a modern day solution to the problems associated with rapidly escalating waste volumes.Changing the waste landscape in South Korea
In 1996, Envac signed an agreement with Korea Land Corporation to install its technology as part of the Sooji project. As the world celebrated the arrival of the Millennium, Yongin City, a densely populated city in South Korea, welcomed its first underground automated waste collection system.
Over 15 years later, the system manages the waste of over 14,000 households, multiple retail outlets, restaurants and offices throughout the area. Collecting 28 tonnes of waste every day from 450 waste inlets across two fractions, the system remains one of the largest of its kind worldwide. Similar to Monaco, one of the fractions is also piped directly into an incinerator that creates enough energy to support the households that use the system,
In fact the system, which spans 105 buildings including 20 apartment blocks, has been so successful that developers in many municipalities within the densely populated region of Seoul are now legally obliged to install a vacuum waste system in developments that exceed a certain size.
An evaluation of the Sooji project revealed that more than 90% of its inhabitants are satisfied with the system and that 70% believe that it has added value to their properties.More Waste Management World Articles
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