To Oulu on rubber tyres – value of waste increases
In Savukoski, the municipal consortium Lapeco's ecoASEMA station manager advises the couple where to sort their waste. The large trailer contains debris from the demolition of the yard building: plasterboards, wood, wool, plastic carpet, insulating plastic, roofing felt… Unsorted construction and demolition waste is dumped into a pile. The load also contains scrap metal, which the couple leaves at the metal collection point.
EcoASEMA is open every other Friday. That's enough to cover the needs of a thousand residents in the county. Lapeco is responsible for municipal waste management in nine municipalities in Lapland. Each municipality has its own recoverable waste station or a larger transfer station. The materials from the stations are transported on trucks by road: recyclable metal scrap, such as the metal scrap just left above, goes to Tornio, and unsorted construction and demolition waste goes to Oulu.
The demolition waste from the old yard building does not sit around long at the station. It is loaded onto a truck and then it travels through the rugged scenery of Lapland on rubber tyres to Oulu. It's about 380 kilometres.
The facility sorts and sifts
The Oulun Energia waste sorting plant, which was commissioned last year in Rusko, Oulu, receives the load from Savukoski. OEKITA handles 100 000 tonnes of construction and demolition waste, as well as commercial and industrial waste from northern Finland, every year.
A couple from Savukoski also slips the remains of a small yard building into the yard of the sorting facility – a facility where the best place for the materials is searched for and found through a multi-stage process.
In the plant, metals, including nails from boards, and unwanted materials such as pvc plastic and electrical wires are sifted out. "Demolition waste, in particular, is quite challenging when it contains materials that have not been prepared for recycling. For example, wood, which is abundant in buildings, has often been treated by varnishing or painting, or some other material, such as nails or plastic, is attached to it,” says Heikki Harju-Autti, circular economy manager at Oulun Energia.
Sorting is carried out mechanically and optically by highly automated equipment. Even before the waste is fed in, rough sorting is carried out, which removes problematic pieces such as ropes that would get tangled up in the equipment. In the actual equipment, waste is crushed and magnets are used to recover magnetic metals.
Recyclable materials such as plastics, metals, wood, and fibres are sorted out of the waste. For example, after the treatment, the plasterboard walls of the former yard building from Savukoski end up in Southern Finland, where the plaster gets a new lease on life as new plasterboards.
Approximately 30% of the mass of material handled by the plant is used for recycling and recovery. Even dust can be utilised.
Construction and demolition waste produces a lot of fine minerals, such as concrete and dust. It is screened and processed and used for landfill construction and other civil engineering projects where fine materials are permitted to be used.
50–60% of the material mass is used as high-quality, solid recycled fuel in Oulun Energia's bioenergy plant, where electricity and district heating are produced.
"This material is not suitable for recycling, but it is better than the material that goes to be burned in an ecopower plant," explains Harju-Autti.
The cleanliness of the fuel burned at the bioenergy plant is important, to enable it to be burned without damaging the boiler; the temperature and pressure of the steam produced at the bioenergy plant are high to maximise electricity generation. Therefore, municipal waste, for example, is not suitable as a fuel for a bioenergy plant.
Only waste that is not used for recycling or as a recycled fuel is incinerated in an ecopower plant.
Transporting waste is the best solution
Let's go back to Savukoski for a moment. Prior to the completion of the waste treatment plant, construction and demolition waste delivered to Lapeco's ecoASEMA was treated on-site. It was mechanically sorted and crushed. Everything that was not suitable for recycling or was not hazardous waste was transported to the Laanila ecopower plant in Oulu for incineration.
"Now we do mechanical sorting and crushing considerably less, which reduces the amount of noise. We still treat stone materials such as concrete waste locally, because we can use them in ecoASEMA structures in accordance with the MARA regulation,” says Janne Vuolli, operations manager at Lapeco.
What is the point of transporting waste for hundreds of kilometres? Would it not be smarter and more ecological to treat waste at source?
"When the amounts of waste in small municipalities are small, their treatment is expensive, and there is no equipment for it. There is no further treatment of recycled materials, not even a combustion plant, which could be used to recover the heat generated. When waste is sorted in Oulu, its utilisation becomes more efficient. This means that we significantly increase the value of waste,” says Harju-Autti.
And with regard to the environmental burden of transporting waste, it is true that transport causes emissions. In this respect, the world is not yet ready, but it is to be hoped that emissions from transport will be reduced. Already in the near future, heavy traffic will be able to chug along in an environmentally friendly way, as, for example, biogas solutions become more common in vehicles.
This article was originally published in Oulun Energia's customer magazine 2/2021. Text by Kati Jurkko, photos by Kati Leinonen.