It's a sure sign of spring in London. The snow is melting and long-buried cigarette butts are resurfacing. "Basically all litter that's been piling up becomes that much more visible," said Jay Stanford, the director of fleet and solid waste at the city. So, where do they all go? For the past few years, butts collected in the city's pole-mounted bins have been sent to Terracycle, a company that specializes in recycling unusual products.