Oslo owns a biogas plant, transforming food waste into biogas, which is used as fuel by buses and garbage collection trucks in the city. Biofertilisers are also produced at the plant and used by farmers to produce food. This plant is the largest biogas plant in Norway with a capacity for 50,000 tons of biological substances.
Today, citizens in Oslo source separate 46% of their food waste in green bags. Likewise, the city’s recycling stations collected 15,300 tons - 27 kg per person - of garden waste in the same year. This waste was then composted and returned to citizens as soil so they could use it in their gardens.
Oslo aims to utilise the bio-resources from its municipal sewage system by sending the sludge to farmers for their agricultural activities. To ensure high quality sludge content, Oslo actively works to reduce the inflow of wastewater containing micro-pollutants to the municipal sewage network.
Changing citizens’ behaviours remains a challenge, specifically correctly separating their household waste. The bulk of food waste - 64% - is not source separated by citizens, which means this waste ends up in the residual waste stream. In turn, the unseparated waste can only be used for energy recovery purposes.
The national definition of household and commercial waste makes it difficult for Norwegian municipalities to invest in infrastructure for waste treatment that could be used by other municipalities or the private industry. The city’s public treatment plant has unused, free capacity, and the city lacks the necessary capacity for treatment of different waste streams like food waste, residual waste and hazardous waste. For this reason, Oslo’s biogas plant is not utilised to its full capacity, which results in higher cost for citizens.
Main activity field:
Since Oslo started source separating household food waste and plastic in 2012, rates of material recovery of the household waste increased significantly. In 2016, 40% of household waste was either reused or recycled, and only 3% ended in landfills.
liquid fertilisers used by local farmers reduce the demand for mineral fertilisers. This is beneficial because producing synthetic fertilisers involves mining limited resources such as phosphate rock.
Compost and soil qualities from composting garden waste are very popular with both citizens and professional gardeners and reduce the use of other soil and compost resources based on peat. The success of the Oslo circle of garden waste has inspired the city to invite our neighbouring municipalities to further develop the production and quality of different soil products. The success has also influenced other producers and retailers to replace peat in soil products.
It is important to have a good dialogue with the future users when developing new products from waste resources. Oslo’s experience was dependent on having a good and constant dialogue with farmers, professional gardeners and the public transport company to produce a product that meets important quality requirements. The dialogue was organised through research and development projects to produce the right quality, understand the effects from the use of the fertiliser and develop guidelines for its use.
the citizens know about the end product of their waste and the processes that transform the waste into new products, the more likely they are to source separate their waste. The city has done this through information campaigns and open days at the different sorting and treatment plants. The citizens deliver garden waste and buy soil products directly at the city’s recycling stations.