On a hot summer's day in southern Uruguay, Graciela Martinez weighs her plastic waste before dropping it in a designated container by the beach.
In return, she'll receive some virtual money on her phone that she can use for discounts on purchases at restaurants or partnered shops.
It's part of a pilot environmental project called "Plasticoin" aimed at encouraging plastic recycling in the South American country.
"Our mission is to take care of the beach," said Juan Rivero, 34, a telecommunications technician who launched the fledgling project alongside 32-year-old industrial designer Nicole Wyaux.
Their test area is a popular seaside resort called Piriapolis.
Participants register online and then deposit their plastic waste at one of three collection points.
The minimum deposit is two pounds (one kilogram), for which participants are rewarded with 100-400 Plasticoins, depending on the type of waste: 100 for household waste, 200 for beach waste and 400 for microplastics of less than a quarter-inch (half a centimeter).
"It's good to recycle for yourself, for your children and your grandchildren," said Martinez, 50, who says she recycles "everything."