Waste-to-energy, composting, disposal of liquid waste and related services

Chart no. 52 illustrates the types of processing and recovery of materials or energy for the Environment Segment.

Chart no. 52 – Incoming volumes of waste managed by type of plant/activity (t) (2022)

WASTE-TO-ENERGY

In addition to the activities already described of solid and liquid waste treatment and anaerobic-digestion lines at composting sites, Acea Ambiente also manages the waste-to-energy process through the plants of San Vittore del Lazio and Terni. The two plants are operated according to the certified Environmental Management Systems and registration with the European EMAS III scheme (see also Corporate identity, Management systems). Adopting circular economy logic, once all possible material has been recovered, energy recovery generates energy and economic benefits and leads to a notable volumetric reduction — in 2022 the volume of waste leaving the waste system was 24% of the waste-to-energy volume — and the biological stabilisation of waste, minimising disposal in landfills.
In its current configuration, the San Vittore del Lazio plant is the largest in the Lazio Region and plays an important role in the management of municipal waste, both for the advanced technologies used for its construction and for its considerable treatment potential¹⁷⁶. It is composed of three independent waste-to-energy lines designed to be fed with Solid Recovered Fuel (SRF), with the following characteristics:

• 52 MWt of thermal power for line 1 and 56.7 MWt of installed thermal power for each of the other two lines, for a total thermal power of approximately 165 MWt
• 9 MWe of electric power for line 1 and 15.1 MWe for each of the other two lines, for a total power of approximately 44 MWe;
• approximately 400,000 t/year of SRF, sludge and other waste at full treatment capacity.

In October 2022, the Lazio Region issued Resolution no. G14621 to create a fourth waste-to-energy line, enabling the complete processing of waste entering the plant in the case of shutdowns for upgrading or scheduled maintenance, as well as treatment of sewage sludge in compliance with the indication of the Waste Management Plan approved by the Lazio regional authority.
In 2022 289,550 tonnes of waste were processed by the waste-to-energy plants and approximately 251 GWh of electricity was generated, a drop compared to 2021 production (-6%).

Table no. 54 – San Vittore del Lazio waste-to-energy plant: operating data (2020-2022)

(*) Relationship between gross electricity produced and quantity of SRF converted to energy.

The Terni plant is composed of a waste-to-energy line and has the following characteristics:

• 52 MWt of thermal power installed;
• 6 MWe of electrical power installed;
• 120,000 t/year of pulper waste (paper mill waste resulting from the pulping of waste paper), as the maximum potential for incoming

The waste-to-energy plant is also equipped with photovoltaic systems, the primary system on the pulper waste pre-treatment area and a secondary system on the adjacent building, which in 2022 generated approximately 454 MWh of electricity, with around 61% consumed on site and the remainder sold to the grid, in line with previous years. 

In 2022 97,796 tonnes of pulper waste were processed by the waste-to-energy plant and approximately 86 GWh of electricity was generated, a slight decrease compared to 2021 figures.
For data on the emissions of both waste to energy plants see the chapter Air emissions, in addition to the data reported in the Environmental accounts.

Table no. 55 – Terni waste-to-energy plant: operating data (2020-2022)

(*) Relationship between gross electricity produced and quantity of pulper waste converted to energy.

In 2022, a waste research facility was opened within the Berg plant in San Vittore del Lazio to study the re-use of fly and bottom ash. For this project, Acea Ambiente and Berg received an EMAS award in the Best Circular Economy Initiative category¹⁷⁷.
For information on the projects to recover sodium bicarbonate and calcium chloride dihydrate from the treatment of residual sodium carbonate (RSC), as well as on the treatment of fly ash and the recovery of mixed plastics, see the section "The Commitment to Research and Innovation" in the Institutions and the Company chapter.

INTEGRATED WASTE TREATMENT

Acea Ambiente manages major waste management facilities in the Umbria and Abruzzo regions. In particular, in Orvieto, in Umbria, it manages an important systems hub for waste treatment, recovery and disposal, ensuring the integrated cycle of municipal solid waste and equivalent materials, produced by all municipalities in the province of Terni. The landfill site is also authorised to receive special waste.
The Orvieto hub includes the mechanical biological treatment of municipal solid waste, composting and refining of the organic fraction of the sorted waste and disposal in landfills. Management takes place in accordance with the certified Management Systems (see the section Management systems in Corporate identify), with the goal of maximising recovery of materials (production of high-quality compost) and supporting both the production of renewable energy (utilising biogas produced for energy) and, as far as possible, the reduction of waste sent to landfill.
There are beehives at the hub which are used to biomonitor the environment by sampling wax, honey and bee matrices and to plan public educational events aimed at local communities.
Total waste entering the plant in 2022 was 97,661 tonnes, of which 71% (approximately 69,500 tonnes) was sent to landfill and almost all of the remainder was sent to the anaerobic digestion and composting section of the treatment plant for the production of biogas and compost. The end product resulting from the aerobic process is refined and subsequently analysed for its chemical and physical classification as high-quality compost, for use as a raw material in commercial growing, environmental restoration, and for maintaining green areas (for more information see the "Use of Compost in Agriculture" box). 

At the same site, there are two energy production plants powered respectively by the biogas produced by the anaerobic section of the treatment plant and by the biogas produced naturally by the landfill site. The latter is collected through a supply network and sent to two internal combustion engines that transform it into electricity, which is then sold to the grid:

• approximately 7 Mm3 of biogas and 3.2 GWh of energy were produced at the treatment plant in 2022;
• approximately 7 Mm3 of biogas and 9.5 GWh of energy were produced at the landfill site.

In total, approximately 12 GWh of electricity was fed into the grid (for more information see the Environmental Accounts).
The Orvieto hub is also equipped with a photovoltaic plant owed by Acea Produzione, which, in 2022, generated around 515 MWh, of which 99.8% was used for self-consumption on site.
The company Deco operates in Abruzzo, where it is responsible for managing its own plants¹⁷⁸ and plants owned by Acea Ambiente (such as the Grasciano hub¹⁷⁹). In particular,

• a landfill for non-hazardous waste in Casoni (Chieti), divided into four sites with a total capacity of over 900,000 cubic metres, which is nearly full;
• a landfill for non-hazardous waste in Colle Cese in the Municipality of Spoltore (Pescara), divided into three sites with a total capacity of over 1,000,000 cubic metres;
• a landfill for non-hazardous waste in Grasciano in the Municipality of Notaresco (Grasciano 2) with an approximate capacity of 480,000 cubic metres.

The first two of the above plants belong to Deco, while the latter belongs to Acea Ambiente. Biogas for the production of electricity is recovered at all three sites. In 2022, Deco's waste processing plants produced 4,180,996 Nm3 of biogas and 2,656 MWh of electricity.
Deco also operates a Mechanical Biological Treatment (MBT) plant for Municipal Solid Waste (MSW) in Casoni (Chieti). The facility, which recovers materials and SRF, processed 241,642 t of waste in 2022 (see box).

HIGH-QUALITY COMPOST PRODUCTION

Experimentation is currently underway with the University of Tuscia on high-quality compost produced by the Orvieto plant hub, totalling approximately 3,412 tonnes in 2022, for use as agricultural fertiliser, applying the direct product and sowing wheat crops on land at the plant itself (see the dedicated box).
As well as the site in Orvieto, Acea Ambiente has two other composting plants — one in Aprilia and one in Monterotondo Marittimo — while at the composting plant in Sabaudia waste delivery was suspended from 31 October 2019 to allow extraordinary maintenance works to be carried out¹⁸⁰.

The Aprilia plant can recover up to 120,000 tonnes/year of organic waste, with production of electricity and thermal energy integrated with the pre-existing composting section. In the first quarter of 2022, the compost bagging line entered into operation, with the aim of accessing additional markets for the soil improver and activating SRF production line using waste from the same plant. This new line enables waste to be delivered to the San Vittore del Lazio plant and contributes to an increasingly circular economy.
The Monterotondo Marittimo plant has a recovery capacity for the organic fraction of municipal solid waste, garden waste (grass cuttings and material from pruning), and sludge, of 70,000 t/year. Anaerobic digestion and composting facilities are active at both sites, enabling the recovery of electricity and thermal energy. For details on the quantities of biogas and energy produced, see the Energy Segment chapter and the Environmental Accounts.

INTERMEDIATION AND TRANSPORT OF WASTE

In 2022, Aquaser, which loads, transports, recovers and disposes of waste produced by treatment plants, managed 400,000 tonnes of waste (390,000 tonnes in 2021). With regard to intermediation, during the year Aquaser took charge of approximately 166,000 tonnes of waste, of which 137,000 tonnes of sludge is attributable to the Group’s water companies¹⁸¹, and in particular approximately 80,500 tonnes to Acea Ato 2, Acquedotto del Fiora and Acea Ato 5. The dried and dewatered sludge coming from the three Companies was sent to the following end destinations:

• 61% to material recovery operations (pretreatments aimed at agricultural use and composting);
• 13% to recovery of energy (waste-to-energy);
• 26% for

Also this year, due to regulatory constraints direct spreading was not used in agriculture.
Aquaser in particular used its own means to transport approximately 42,000 tonnes of non-hazardous waste.

SELECTION AND SEPARATION OF MULTI-MATERIAL WASTE

The Demap plant, located in the province of Turin, carries out selection and implementation of recycling for plastic and plastic/metal packaging. In particular, it handles the storage, selection, sorting and separation of single and multi-material waste originating from separate waste collection, such as plastic material and metal packaging, for subsequent recovery. The Demap plant is affiliated with the Corepla Consortium, a group of companies established pursuant to Italian Legislative Decree 22/1997 to organise and manage post-consumption plastic packaging, and performs its activity on the basis of a contract for the selection of waste plastic packaging with the Consortium itself. In 2022, approximately 25,400 tonnes of material entered the plant and was processed for separation and recovery.
Meanwhile, almost 6,900 tonnes of waste was processed by Berg, although, as detailed below, the company’s main business area is the storage and treatment of hazardous and non-hazardous liquid waste (for more details, see the Environmental Accounts).

TREATMENT OF LIQUID WASTE

Acque Industriali carries out brokering and liquid waste treatment services for private and public companies, as well as activities related to the integrated water cycle, mainly consisting of the recovery and disposal of organic sludge, through the management of several platforms. In 2022, due to the closure of the Pisa Nord and Pontedera sites, the amount of waste processed fell to around 50,000 tonnes of liquid waste, down 46% compared to 2021¹⁸². In addition, the Company provided brokerage services for approximately 37,000 tonnes of waste during the year (-31% compared to 2021).
Acque Industriali uses technologies that support recovery of raw materials contained in waste, energy saving and the efficient use of resources, such as stripping/absorption of ammonia in a closed cycle that enables recovery of ammonium sulphate, which can be used as an agricultural conditioner, of which 139,040 kg were produced in 2022. The Company also provides services for design, creation and management of plants for the treatment of wastewater for third parties, decontamination of polluted sites and environmental consulting for the management of plants, investing in research and development in the relevant sectors, in collaboration with recognised Research Bodies. For details of the type of incoming waste, the resources used, the waste produced and other specific information, see the Environmental Accounts.

The Berg plant is a polyfunctional platform for the storage and processing of hazardous and non-hazardous waste, authorised for the sale and brokerage of waste and the creation of plants for treatment and processing of liquid waste.
Specifically, the plant has two departments: storage and treatment of liquid waste and storage and treatment of solid waste. In 2022 approximately 93,700 tonnes of waste, both solid and liquid, were processed and brokerage services were provided for a further 6,900 tonnes of waste.
The Bio Ecologia¹⁸³ plant in Chiusi handles the chemical/physical and biological treatment of non-hazardous liquid waste¹⁸⁴ and treatment of sewage. In 2022 approximately 98,000 tonnes of liquid waste and approximately 82,000 m3 of wastewater were processed.

176 With reference to Decree Law 133/2014 (referred to as Sblocca Italia), the plant has been defined as a strategic structure of primary national interest for the protection of health and the environment, as per Lazio Regional Decree no. 199 of 24/04/2016.
177 https://www.isprambiente.gov.it/it/attivita/certificazioni/files/emas/newsletter/2022/newsletter-emas-n3-2022.pdf.
78 Deco's facilities include a Transfer Point where third-party urban waste collection vehicles transfer the collected waste from their own machines to larger-capacity vehicles, and a depot on the quayside of the port of Ortona, in the Province of Chieti, authorised for the storage of waste for recovery, where the SRF to be shipped is stored, providing several logistical, organisational and environmental advantages. This is not included in the reported data due to its negligible significance.
179 The Grasciano site also includes other plants that have been inactive for several years: a platform for the treatment and energy recovery of waste from separated waste collection, a landfill for non-hazardous waste (Grasciano1) and two waste treatment lines (one for mixed and/or similar waste to produce SRF and the other for the wet organic fraction derived from separated waste collection to produce high-quality compost).
180 The liquid waste treatment facility at Sabaudia is currently inactive and studies, analyses and technical and economic assessments are currently underway to identify possible new industrial uses for the site.
181 The data detailed here for the sake of completeness concerns sludge for which Aquaser has managed the entire supply chain, from loading to transport and final disposal, originating from the following Group Companies: Acea Ato 2, Acea Ato 5, Acquedotto del Fiora, Umbra Acque, Publiacqua, Acque and Acea Molise.
182 As well as the two platform closures, the platform at Poggibonnsi suspended its activities in June 2021 pending the re-issue of the standard operation permit.
183 (*) On 1 May 2021, Bio Ecologia Srl was merged by incorporation into Acea Ambiente.
184 The quantities of liquid waste authorised for treatment (excluding wastewater) have a maximum limit of 99,900 tonnes/year.