In the recently published Urban Water Atlas for Europe, Stockholm is rated as one of the leading cities in Europe in terms of wastewater treatment Click & Tweet! and solid-waste treatment.
Stockholm is one of the fastest growing cities in Europe with its population expected to increase by 11% by 2020 to reach just over 1 million inhabitants. This steady population growth will mean an increase in waste from both households and businesses.
A world-class response
Two of the main objectives of Stockholm’s Waste Management Plan (2013-2016) is that waste produced will be dealt with in a resource-efficient way and that waste management will be a natural part of the planning process. Specifically:
- 60% of phosphorous compounds in wastewater will be returned to productive land, of which at least half to farmland
- Waste will be prevented and a greater proportion of products will be re-used
- Cooperation between facilities for new energy solutions must be intensified
Stockholm’s world-class waste solutions
To fulfill the city’s waste management objectives, Stockholm Water and Waste is taking advantage of the products generated in its wastewater treatment process to create fertilizer and biogas.
Each year, Stockholm’s Bromma sewage treatment plant produces around 1 million tons of sewage sludge. After dewatering around 70,000 tons of sludge remains which is then used to produce fertilizer. Between 2015-2018, Bromma aims to produce 120 tons of phosphorous per year for agricultural use. To ensure the sludge used to produce phosphorus for agricultural use is of the highest quality the sludge is certified by Revaq, which is a certification scheme aimed at reducing the flow of hazardous substances into sewage treatment plants, ensuring sustainable nutrient recycling.
Fuel from sludge
During the digestion process, around 4.1 million m³ of biogas is produced annually which is then sold to Scandinavian Biogas for conversion into environmentally-friendly fuel for the city’s bus fleet. The biogas is even used to power some of the city’s taxis and private cars as the biogas is sold at filling stations around the city. Overall, the biogas saves more than 22,000 tons of carbon dioxide each year.
Wastewater treatment infrastructure can be used to fulfill multiple waste and renewable energy policy objectives.
*Robert C. Brears is the author of Urban Water Security (Wiley), and of the forthcoming titles Blue and Green Cities (Palgrave Macmillan) and The Green Economy and the Water-Energy-Food Nexus (Palgrave Macmillan). He is Founder of Mitidaption, which consults on climate change risks to business, governance and society.