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Waste produced by Hera

The activities managed by the Hera Group generate various waste types: on the basis of the specific chemical-physical characteristics of the waste, it can subsequently re-enter the recovery (energy or material) or disposal processes managed within the Group.

Main types of waste produced by Hera
thousands of t200920102011
Sludge from purification, treatment and distribution148129133
Sand from wastewater treatment plants191819
Ash from purification sludge incineration432
Other sludge produced by the Territorial Operating Structures (sewer cleaning, septic tanks, etc.)642
Other waste produced by Territorial Operating Structures121
Waste-to-energy plant electrofilter dust252845
Waste-to-energy plant waste167178188
Solid waste from stabilisation412738
Sludge produced by chemical-physical-biological plants6910285
Sludge treatment water97354369
Separated oils produced by chemical-physical-biological plants010
Surnatant from chemical-physical-biological plants592500251
Leachate from landfills458781491
Scavenging water/sludge from waste-to-energy plant fumes1256266
Non-reusable fractions from plants for selection and for the production of fuel from waste160176155
Other waste from Herambiente storage and plants242235

Data refer to Hera S.p.A., Herambiente, Akron, FEA, Nuova Geovis, Romagna Compost, Marche Multiservizi from 2010; Enomondo and Feronia from 2011.

In 2011, the Group produced around 1.9 million metric tons of waste. In 2011, the quantities of waste produced by waste-to-energy plants (waste, dust and solid waste from stabilisation) increased due to the increase in quantities of waste sent to waste-to-energy plants. Leachate and waste from chemical-physical-biological plants fell because of the lack of rainfall during the year and, as a result, the fall in the production of by-products. The production of non-reusable fractions fell because of the lower quantities treated by selection plants as a result of the lower quantities of special waste treated.

The following are the disposal methods used for the main types of waste produced by the Group's operations:

  • sludge generated by water offtakes, treatment and distribution: dehydration, landfill, reuse in environmental renovation works;
  • purification sludge: landfills, conditioning and subsequent reuse in agriculture, thermal treatment, dehydration, transfer directly to agriculture;
  • dust from waste-to-energy plants: stabilisation and successive disposal in appropriately controlled landfills;
  • waste from waste-to-energy plants: landfills, recovery of iron and metal fractions, production of concrete and bricks;
  • surnatant from chemical-physical-biological plants: biological purification treatment in plants;
  • leachate from landfills: treatment in chemical-physical-biological plants;
  • non-reusable fractions from plants for selection and for the production of fuel from waste: waste-to-energy, landfill.

Recovery of waste-to-energy treatment plant waste

The growth and plant renovation plan pursued by Herambiente in recent years on its pool of waste-to-energy plants has had a positive impact on the production of combustion waste. The new combustion systems and, above all, the "gondola"-type combustion waste "cooling" (i.e. the operation to cool the waste produced in the oven by soaking it in water baths) and extraction systems make it possible to have waste with a very low quantity of unburned matter and reduced water content. This resulted in a both lower percentage of waste produced and, above all, a waste quality level more suitable for subsequent recovery.
In 2011 the 6 waste-to-energy plants managed by Hera for the disposal of urban waste produced 166,317 metric tons of waste, equal to 21% of the waste treated at these plants. 55% of the waste produced was recovered while the remaining 45% was disposed of at landfills. The recovery takes place in third party plants, thanks to consolidated, long-term commercial agreements in place. The waste is used to produce second raw materials, which are used in the production cycles of concrete and bricks. During the process, ferrous and non-ferrous metals are also recovered and then reused in the metallurgical industry.