MR TRASH WHEEL

At the mouth of the Jones Falls River, where it feeds into Baltimore Harbour in the US, sits Mr Trash Wheel. Since 2014, this semi-autonomous floating rubbish collector has scooped up more than 500 tonnes of detritus, including 9,000,000 cigarette butts, 492,000 coffee cups and 376,000 crisp packets. Mr Trash Wheel cost $720,000 (£560,000) to build, and has now been joined by Professor Trash Wheel, a ‘female’ version in a different part of the harbour.