Main types of waste produced by Hera thousands of t Sludge from purification, treatment and distribution 173 192 148 Sand from wastewater treatment plants 13 20 19 Ash from purification sludge incineration 4 4 4 Other sludge produced by the Territorial Operating Structures (sewer cleaning, septic tanks, etc.) 25 11 6 Other waste produced by Territorial Operating Structures 6 1 1 Waste-to-energy plant electrofilter dust 9 14 25 Waste-to-energy plant waste 91 93 167 Solid waste from stabilisation 20 12 41 Sludge produced by chemical-physical-biological plants 53 53 69 Sludge treatment water 129 78 97 Separated oils produced by chemical-physical-biological plants 1 0 0 Surnatant from chemical-physical-biological plants 380 489 592 Leachate from landfills 259 292 458 Scavenging water/sludge from waste-to-energy plant fumes 136 152 125 Non-reusable fractions from plants for selection and for the production of fuel from waste 124 112 160 Other waste from Waste Management Division storage and plants 1 7 24 Total 1,423 1,532 1,936 Data refer to Hera S.p.A., Herambiente, Akron, FEA, Nuova Geovis, Romagna Compost.