“Nothing grows out of diamonds. Out of dung, flowers do grow,” used to sing Fabrizio De André in 1967. Asking the poet’s for forgiveness, fifty years on we can go a step further and state that out of sludge, fuel can grow. We are talking about biomethane obtained from wastewater, i.e. the so-called sewage sludge, black water’s waste products. This is Biometanow’s objective, the project of circular economy and recovery of resources developed by Gruppo CAP, the public company managing the integrated water service in 134 municipalities of the Milan metropolitan area and an additional 64 in the Monza, Brianza and Pavia provinces, totalling 6,483 kilometres of water network, 782 wells and 294 water treatment plants. Overall, every year, the structure provides about 200 mill...