Why don't you promote the use of the Litterati app?
The Litterati app can be used to register the pieces of litter people pick so that the data becomes available for research. The data gives insights into which materials are found (plastic, paper, aluminium etc), which brand names are found (coca cola, marlboro etc) and the location (close to a garbage bin or not, etc). It is used a lot in the Netherlands, the USA etc. But not so much in Sweden.