London's 130-tonne 'fatberg' of human waste is being turned into biofuel for the city's buses

Lurking underneath the streets of London, a giant clump of congealed human waste hit the headlines last week. The so-called ‘fatberg’ is 820ft (250 metres) long and formed from a mixture of fat, grease, oil, wet wipes and sanitary products. It weighs the same as 11 double-decker buses.