Attention to the use of water resources

Water resources are used in a number of industrial processes, such as the generation of electricity and thermal energy, the compost producing processes, as well as clean treatment plant tanks and an- aerobic digestion tanks. Water is also used in small quantities for laboratory activity.

Group companies are committed to reducing drinking water withdrawals and implement measures to enable the use of recycled water. In this regard, there has been a gradual increase in the quantity of recovered water, from around 2.2 million m³ in 2021 to almost 2.7 million m³ in 2023, an increase of 21%. Specifically, in 2023 certain companies in the water sector developed initiatives to reuse treated water within the treatment plants themselves. The treatment plans currently managed by Gori for example, re-use the treated effluent The wastewater used for this purpose, defined as “technical wastewater”, is distributed within plants through specific pipes and used for washing equipment (screens, units for thickening and drying of sludge), backwashing of certain parts of the treatment plant (membranes, fabric or sand filters), and washing of sand and screens. The first reused water-flow meter was installed at the Scafati plant; additional flow gauges are expected to be installed in 2024 with the implementation of water audits to assess water withdrawals and consumption from treatment processes and identify strategies to increase savings and reuse possibilities.

Acea Ato 2, for some years now, has implemented restructuring and integration in the industrial water network based on a logic of sustainable and circular water management of the water resource, so as to optimise the internal uses of drinking water (non-drinking water, recovered from the output of the treatment process for ur- ban wastewater) at the main treatment plants: “Roma Sud”, “Roma Nord”, “CoBIS” and “Ostia”. In 2023, the Company further extended the industrial water networks at the Roma Sud treatment plant, so that industrial water could be used in the new thermal dryer and at the Ostia treatment plant, making it possible to reuse the treated water at the new soil washing plant under construction²³⁶. The programme of interventions underway has already increase the volume of treated water reused internally as process water, by about 1.8 million m3 in 2022 to approximately 2.1 million m³ in 2023, corresponding to around 52% of the total water used. At Acea Ato 5 approximately 534,600 m³ of treated water was used in the same treatment plants for the services relating to their operation (washing of screen systems and filtration, service water to operate the drying systems, irrigation of green areas, etc.)

The Companies in the Environment segment limit the use of drinking water, mainly using water from wells. In addition, at the plants of San Vittore del Lazio, Orvieto Ambiente, Aprilia, Monterotondo Marittimo and Terni, there are active systems for the recovery of rainwater. At the Terni plant, for example, rainwater is collected in two tanks equipped with a filtration system and storage tanks, before industrial use. The Aprilia composting plant also has a system for treating residual water from unprocessed waste, allowing it to be reused in production processes. The Monterotondo Marittimo plant also has a rainfall recovery system that, after phytodepuration, enables collection of the water in special aerated reservoirs as a reserve for fire-fighting and as a reserve of industrial water for process use237. At the waste-to-energy plant in San Vittore del Lazio, rainwater goes through a special chemical/physical treatment process to produce demineralised water, which is then entirely reused within the same system as part of a closed cycle, with no water discharge to the environment. The Orvieto Ambiente plant hubcollects rainwater from the roofs of certain buildings and transfers it to underground storage tanks serving the fire-fighting reserve. The Chiusi plant of Acea Ambiente, recovers water from the final effluent: the recovered water is used to wash surfaces at the plant. Thanks to the various solutions described, a volume of approximately 65,339 m³ was recovered from the Environment segment in 2023.

A project is underway at the Tor di Valle thermoelectric power station to reuse water after treatment for industrial purposes in the district heating network.
Water withdrawals of the main Group companies associated with industrial processes and civil use are illustrated in Table 67. While withdrawals were slightly up during the year, the measures detailed above have significantly increased the amount of re-used water over the three-year period.

The reuse of treated waste water is an effective response to water stress in Acea’s areas of operation, but specific regulatory interventions are required to further expand its potential. In this sense, the recent European Regulation 2020/741 on the reuse of treated water in agriculture, in addition to setting the provisions that will be adopted with national regulations, facilitates the option of increasing this reuse.

Table no. 67 – Water withdrawal and recovery (2021-2023)

Note: intake of freshwater occurs in areas at potential risk of water stress, as defined by the Aqueduct Water Risk Atlas, the map drawn up by the World Resources Institute (WRI). (*) The figures for the 2021-2022 two year period have been adjusted following consolidation and changes to the calculation method.
(**) Water withdrawn for industrial use was partly used in processes totalling 0.090 Mm3 in 2021, 0.179 Mm3 in 2022 and 0.148 in 2023; the discharge of water withdrawn for industrial use over the three-year period was 0.009 Mm3 in 2021, 0.007 Mm3 in 2022 and 0.001 in 2023.
(***) The data refers to river withdrawals for the Orvieto Hub and sites managed by Deco.
(****) Water withdrawn for civil/sanitary use from aqueducts, representing 99.9% of total withdrawal for this purpose, is discharged into the public sewerage system after reuse and returned to the environment.
(*****) Out of the total water withdrawn, water consumption in the three-year period was 8% in 2021, 12% in 2022 and 10% in 2023.

The Group promotes informed and careful use of water resources, also throughout the supply chain, raising awareness among suppliers through issue of a questionnaire (see also the sub-section Energy consumption along the supply chain).

Discharges of water withdrawn and used occur within the scope of authorised and closely controlled processes. For example, at the Terni waste-to-energy plant, residual water from production processes is first treated by internal treatment plants, and then discharged into public sewerage. Water used in the waste-to-energy process at the San Vittore del Lazio plant is collected and stored in special underground tanks and then disposed of as waste, as it may contain substances that make it unsuitable for normal discharge. Wastewater from toilet facilities on the production lines and at the relevant offices is collected in septic tanks and subsequently disposed of, while the sewage from the administration building is collected and conveyed to an Imhoff tank with a sub-irrigation system for subsurface clarification.
Water intake for industrial uses in activities connected to the integrated water service, and in particular water treatment, undergoes the same treatment as waters transported via public sewerage, i.e. it is retreated at the treatment plants and sent to the locations described in the section Sewerage service and treatment system, in the chapter Water Business. The civil water intake from the aqueduct ends up directly in the sewer network.

236 Located at the Ostia treatment plant, the new sand washing treatment plant, will make it possible to recover up to 80% of the incoming solid material, with the aim of generating three types of products that can be used on the market as secondary raw materials (sand, gravel and pebbles) in the building or road works sectors. In addition to the recovery of waste made up of solid-sandy materials generally destined for disposal, soil washing exploits the synergy with the nearby Ostia treatment plant, from which it receives the treated water to use in its washing process, and returns the process water ad forecourt water for treatment, thus optimising the water usage.
237 A non-substantial amendment to the integrated plant authorisation was approved during 2023, which requires various improvements to reorganise the water recovery system, including the recovery of rainwater coming from the roofs. The high quality and quantities of water from the roofs will further reduce the network’s consumption of drinking water.
238 Suppliers’ water data parametrized in relation to the portion of work/services sales for Acea.