Waste produced by the company
In 2017, excluding AcegasApsAmga, the Group produced around 2.4 million tonnes of waste. The amount of waste produced by waste-to-energy plants (slag, particulate and solid waste from stabilization) increased, particularly in the Triveneto region. Slag produced by landfills has increased and, scope being equal, also by selection plants and by chemical-physical-biological plants, due mainly to weather. Waste from waste selection plants is on the increase, as a result of the entry of Waste Recycling.
|thousands of tonnes||2015||2016||2017|
|Sludge from purification treatment, potable water treatment and distribution||116||110||165|
|Sand from treatment plants||16||17||10|
|Ash from treatment sludge incineration||3||3||3|
|Other sludge produced in the field of the integrated water service||5||4||4|
|Other waste in the fields of the integrated water service and gas and electricity distribution||4||4||10|
|Waste-to-energy plant electrofilter particulates||47||52||47|
|Waste-to-energy plant slag||230||259||266|
|Solid waste from stabilization||44||51||101|
|Sludge produced by chemical-physical-biological plants||61||65||45|
|Sludge treatment water||616||781||543|
|Separated oils produced by chemical-physical-biological plants||1||1||1|
|Surnatant from chemical-physical-biological plants||106||95||71|
|Leachate from landfills||633||560||427|
|Scavenging water/sludge from waste-to-energy plant fumes||48||40||49|
|Non-reusable fractions from selection plants and to produce fuel from waste||284||360||430|
|Other waste from Herambiente storage and plants||38||101||221|
|of which non-hazardous in landfills||342|
|of which non-hazardous for energy recovery||128|
|of which non-hazardous for other treatment||1,758|
|of which hazardous in landfills||39|
|of which hazardous for energy recovery||8|
|of which hazardous for other treatment||118|
I The data do not include Hera Luce and Uniflotte whose waste can be estimated at 0.2% of the total. Urban waste produced in the premises was not considered.
Recovery of waste-to-energy plant slag
The waste-to-energy plant growth and renovation plan pursued by Herambiente in recent years has had a positive impact on the production of combustion slag. The new combustion systems and, above all, the systems for the “cooling” and “gondola”-type systems to extract combustion slag, make it possible to have waste with a very low quantity of unburned matter and low water content. This has resulted in a lower percentage of slag produced and, above all, a quality level more suitable for subsequent recovery.
In 2017, the 9 waste-to-energy plants operated by the Group for the disposal of municipal waste (excluding the Ravenna F3 plant) produced 257,587 tonnes of slag, 20.5% of the waste treated at these plants. 81% of the slag produced was recovered while the remaining 19% was disposed of at landfills. The slag produced by the Herambiente plants and to be disposed of was sent to the Group’s landfills of Castelmaggiore (Bologna) and Ravenna, while the waste to be recovered was sent to plants located in the Provinces of Pavia, Pavia and Ravenna. The slag produced by the Hestambiente plants is recovered in third-party plants in the provinces of Padua and Verona.
Slag recovery is carried out in third party facilities, and is used to produce secondary raw materials, which are then used to manufacture concrete and bricks. The Ferrara and Pozzilli plants also have a metal separation system for reuse of the metal in the metallurgical industry: 1,522 tonnes of metal were recovered in 2017.
Recovery of treatment sludge
Treatment sludge is considered special waste and must be managed as specified in Legislative Decree 152/2006. In 2017, the plants operated by the Group produced 37 kg of sludge per population equivalent served, in line with the previous year. Sludge used directly in agriculture accounts for 3.4% of the total. Recovered treatment sludge was used directly in agriculture only in the Triveneto area. At Group level, the remaining sludge produced was processed by dedicated incineration (24,387 tonnes, 14.8% of the total), transfer to landfills (approx. 16,442 tonnes, 9.9% versus 12.1 in 2016 and 19.0% in 2015) and indirect agricultural reuse, following composting (109,112 tonnes, 66.0%). The use of Herambiente’s industrial sludge treatment plant in the province of Ravenna has contributed to reduce by 3 million tonnes the sludge disposed of in landfills as such: the sludge treatment makes material that can be used to cover landfills and fill the cavities of mines.