What do old televisions, street signs, motorbike helmets, windsurf boards, and Christmas trees have in common? They were all caught floating down Amsterdam's Westerdok canal -- by a curtain of bubbles.
"The Bubble Barrier" was developed as a simple way to stop plastic pollution flowing from waterways into the ocean. An air compressor sends air through a perforated tube running diagonally across the bottom of the canal, creating a stream of bubbles that traps waste and guides it to a catchment system.
It traps 86% of the trash that would otherwise flow to the River IJ and further on to the North Sea, according to Philip Ehrhorn, co-founder and chief technology officer of The Great Bubble Barrier, the Dutch social enterprise behind the system.
"It concentrates on the trash that would otherwise flow off unseen and underwater even," he says. "It literally brings to the surface, [that] which was otherwise never seen."