Chewing gum and grease removals

The common dirt in our sidewalks, pavements and roads are chewing gums from (filthy) people and grease from vehicles.

In this project, besides the mentioned graffiti, gums and grease have been spread over the platforms to prove if the photocatalytic materials are able to remove them.

In the photo below, they can be seen: the gum (small white circle on the left) and the grase (next to it, big black circle).