Maryam Lawani, struck by the amount of plastic waste left on the streets of Lagos, Nigeria's commercial capital after the rains, founded Greenhill Recycling in 2015. It now recovers an average of 100-200 tonnes of waste monthly, while providing a means of supplemental income for people around her, who earn around 100-150 naira ($0.1265) for every kilogram of trash collected. "Waste is a currency to address other issues around poverty, unemployment and the environment. People are able to exchange waste for profitable things like school fees, clothes and even food," she said. It is one of several women-led upcycling and recycling companies that have sprung up in Africa's largest economy.