With demand of natural resources increasing and supply decreasing, the use of recycled materials is gaining importance.
Mineral resources like concrete, bricks or ceramics can be found in large quantities in many buildings across countries like Germany. Metals such as steel, copper, and aluminum, and materials like plastic, gypsum, asphalt and wood are also abundant. Household waste is also a major source of valuable materials.
Urban mining has many advantages over primary mining: the materials are already in the city where they are likely to be needed again, so there is no need for long transport routes. And the environmental impact, particularly in land use, is clearly lower than mining for natural resources.
"As the use of fossil fuels becomes more complex and expensive, recycling secondary raw materials will become more competitive," predicts Jasmin Mangold of Bonn Orange, a German waste management company.
Just about everything can be reused
Each German produces almost 500 kilograms (1,102 pounds) of waste per year. Workers at the Bonn Orange recycling facility in Bonn, Germany, struggle to sort out all kinds of citizen waste: computers, televisions, refrigerators, washing machines, batteries, fluorescent lamps, rubble, CDs, oils and paint.
The paint is dried up to make chalk, the rancid oils are processed into cosmetics, and old devices dismantled to recycle materials such as paper, plastics, metals or glass, workers explained to DW.
Buildings, furniture, electrical appliances and old radiators are just as much part of industrial society's "anthropogenic deposits" as disused railways, industrial wastelands, underground cables or that old cell phone forgotten in the depths of your drawer.
These so-called secondary raw materials can be reused for commercial and industrial production, thus limiting imports from abroad, protecting natural resources and the environment.
For recycling experts, a simple car represents a large manmade stock of raw materials; even a rusty old car has value. The Internet is full of retailers looking for gears, doors and other replacement parts. The iron, plastic, glass and metal can all be sold to make new products. Tires can be processed into road surfaces or insulating material.
A fortune in waste
"We are surrounded by a manmade stockhouse of more than 50 billion tons of materials," Maria Krautzberger, president of the German Environment Agency (UBA), said in a statement.
If all industrial infrastructure, buildings, and waste products were considered as valuable materials, this would represent for each German citizen: 317 tons of mineral materials, 14 tons of metal, more than 4.3 tons of wood and 3 tons of plastics.
And this anthropogenic deposit is growing each year by another 10 tons per inhabitant of Germany, according to UBA data.
The value of metals alone in Germany's anthropogenic deposit is estimated at €650 billion ($800 billion). In an ongoing shift, those materials are being viewed not as a burden, rather as a fortune.
Urban mining for a circular economy
"Recycling is a key industry for the way to a resource-efficient circular economy," Felix Müller, an industrial chemist with UBA, told DW.
The production of a one-ton car requires 15 tons of primary raw materials, including mineral ores and fossil fuels.
"Secondary raw materials represent high savings, because they do not have to be refined — only melted down," Müller explained.
By means of comparison, "To produce one ton of electrical steel from scrap, only 0.8 tons of primary raw materials are required and only one-third of the energy input," Müller pointed out.
At least in Germany, that seems to be acknowledged as the way forward: 30 percent of semi-finished copper and copper casting production in Germany, for instance, is already produced from domestic copper scrap, according to the UBA.
Recycling also enjoys high popularity among citizens, and is often the public preference to plundering natural resources abroad or shipping large quantities of garbage to Africa or China.
Backing this up more broadly, circular economy has been identified as a major target across the European Union.