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Water treatment

Our expertise in water.

How we manage water

We are involved in major groundwater remediation projects throughout the country. The measures are implemented through an Integrated aquifer interception and treatment system, consisting of:

  • over 1200 groundwater extraction wells
  • about 5,000 wells for monitoring and conveying water to treatment plants (GTP) fo purification
  • 42 water treatment plants, of which 26 owned.

We also manage urban and industrial biological treatment systems at the sites in Gela, Cengio and Manfredonia. All the assets are compliant with Best Available Technology (BAT) and Best Available Technology Not Entailing Excessive Cost (BATNEEC).

Water treatment systems

The water treatment processes include strict monitoring systems to ensure that the quality of water discharges and atmospheric emissions are fully respected. To facilitate the recovery and use of water resources and with a view to the circular economy, we support research into innovative solutions for sustainable and efficient water management, with the aim of maximising reuse and reducing withdrawals of water from nature. To do this, we have installed and activated special sections for the production of demineralised water at the GTP plants in Priolo, Porto Torres, Assemini and Brindisi, for reuse by the industrial plants. In other cases, such as in Manfredonia, the treated and osmotised water is partially re-injected into the groundwater to restore the natural conditions of the aquifers. During 2021, we treated about 36 million cubic metres of water, recovering about 9 million cubic metres mainly for industrial use.

The water management systems on our sites and under mandate

Crotone

The site's hydraulic barrier system has been in operation since 2009 and was expanded in 2017. The extracted water is sent to the consortium plant operated by a third party.

Priolo

The site's seafront physical and hydraulic barrier system extends for 4.5 kilometres. The water treatment plant has been in operation since 2009 and has a capacity of 600 m3/h. A second GTP plant is used to treat water from the area of the former Propylene Oxide plant (capacity 10 m3/h). Some of the treated water is osmotised and reused.

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Avenza

The hydraulic barrier system consists of 32 wells and a GTP treatment plant with a capacity of 200 m3/h, which was expanded in 2018.

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Mantua

There are three treatment plants at the Mantua site: the TAF, in operation since 2010, the TAR, which treats runoff water from construction sites, and the TAD for dewatering excavation sites.

Assemini

In Assemini, there are a number of hydraulic barriers and groundwater extraction systems, both within and outside the site. The groundwater treatment plant has a capacity of 180 m3/h. It began operation in 2005 and was expanded in 2016.

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Porto Marghera (Venice)

The physical and hydraulic barrier system delivers the water to the treatment plant, which began operation in 2009 and has a capacity of 50 m3/h.

Cengio

In Cengio there is a physical barrier at the site and a hydraulic barrier system for the external areas. The water treatment plant began operation in 1988, it has a capacity of 350 m3/h and also treats urban waste water from neighbouring municipalities.

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Brindisi

A hydraulic barrier system is active and a water treatment plant with a capacity of approximately 200 m3/h is in operation at the site. Part of the treated water is sent to Enipower's reverse osmosis membrane plant for demineralisation and subsequent re-use on the site.

Gela

Treatment with a physical and hydraulic barrier system, the extracted water is delivered to a plant with a capacity of 300 m3/h. A second plant (capacity of 10 m3/h) pre-treats the water coming from islands 1 and 2. The groundwater remediation facilities were completed and commissioned by the Gela Refinery in 2007. The latter transferred management to Eni Rewind in 2017.

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Pieve Vergonte

A hydraulic barrier system is active at the site. The extracted water is sent to the TAF plant, it began operating in 2002, was expanded in 2019 and has a capacity of 1250 m3/h.

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Manfredonia

A hydraulic barrier system is active and a groundwater extraction system is in operation at the site. The water is sent to the GTP plant, which began operation in 2005 and has a capacity of 150 m3/h. Once treated, part of the water is returned to the water table.

Ferrara

The site has a groundwater treatment plant, which began operation in 2006. It treats water from zone 8 and, since the 2017 expansion, pre-treated water from the IFM consortium. Some of the water is recovered and reused for industrial purposes at the plant.

Cesano Maderno

The site has a hydraulic barrier system consisting of 7 extraction wells with a total flow rate of 400 m3/h. Some of the water is recovered for reuse.

Ferrandina

Activity managed by Eni Rewind under mandate. A groundwater treatment plant operated by Eni Rewind is in operation at the site.

San Gavino Monreale

A hydraulic barrier system is active and a groundwater treatment plant is in operation at the site, it started up in 2010 and has a capacity of 36 m3/h

Rho

Activity managed by Eni Rewind under mandate. A hydraulic barrier system consisting of 6 groundwater extraction wells with a total flow rate of about 200 m3/h is active at the site.

Fornovo

Activity managed by Eni Rewind under mandate. A hydraulic barrier system is active on the site and a GTP groundwater treatment plant with a capacity of 80 m3/h is in operation.

Ponte Galeria

Activity managed by Eni Rewind under mandate. Hydraulic barrier system. GTP plant with a capacity of 25 m3/h. Treated water is partly returned to groundwater and partly discharged into surface water bodies.

Ascoli Satriano

Activity managed by Eni Rewind under mandate. The site has a hydraulic groundwater extraction system consisting of 5 wells and a groundwater treatment plant with a capacity of 10 m3/h.

Napoli

Activity managed by Eni Rewind under mandate. A hydraulic barrier is active at the site and a groundwater treatment plant is in operation with a capacity of 7 m3/h.

Porto Torres

A hydraulic barrier system is active and a treatment system consisting of 5 plants is in operation at the site. These plants started up between 2004 and 2018, and have a total capacity of 360 m3/h. Part of the treated water is recovered and converted into demineralised water.

Val d'Agri

Three mobile groundwater treatment plants operated by Eni Rewind are in operation at the site. The plants have been running since 2018 and have a total treatment capacity of 70 m3/h.

Centralised control room

A control room, operating 24 hours a day, has been set up in San Donato Milanese to remotely monitor and control 25 of the 42 plants.

We have specific technologies for each contaminant

Our plants use ad hoc technologies depending on the contaminants and salinity present and any salinity. They include chemical-physical sections (metals), stripping (organic chlorides), filtration with activated carbon (organic), biological treatment (ammonia compounds), osmosis (salinity) and purification to return water to the water table so that it can be recovered or reused at Eni sites. 

In line with our mission, we are driving the optimisation of water treatment processes to reduce water consumption by finding new technical solutions and continuously upgrading our facilities. Greater production efficiency means greater respect for the environment and the health and safety of our workers. In Crotone, for example, we have completed the automation and digitalisation of the pump & treat systems with a tool that controls the flow rate of wells. This ensures that only the necessary amount of water is extracted from the groundwater to carry out remediation operations. In Priolo, there is also a new Dynamic Control System, borrowing from experience in the refining sector, which allows the simultaneous, real-time monitoring of pressure, flow and acidity. Its installation has reduced energy consumption (-10%) and reagent consumption (-15%) and has led to an increase in the production of osmotised water. Also in Priolo, in 2019, the project for the construction of the permeable reactive barrier was approved. This is a remediation system that intercepts the groundwater through the construction of a trench (barrier), which contains specific reactive materials that act on the contaminants, removing approximately 90% of them in the first stage of the barrier.

Sustainable management of production water in Val d'Agri: Blue Water technology

Our experience in water management has enabled us to develop, together with Eni research laboratories, a technology called Blue Water, was ideated to treat and recover production water from crude oil extraction activities, with a view to ensuring the lowest possible environmental impact. Its implementation will make it possible to regenerate production water, as is the case in traditional purification plants, returning it to surface water bodies or, after further treatment, making it available for industrial use. This reduces the disposal of outgoing residues (salt solutions and sludge), which will be disposed of at suitable external plants and minimises the withdrawal of water from natural sources. At the Val d'Agri Oil Centre in Viggiano, Basilicata, we have designed the first industrial-scale plant that will treat part of the production water that is currently sent for disposal, so it can be used to meet the water needs of the industrial site. The process of authorisation with the local authorities is currently in progress.

Remote control of GTP plants

In 2016, we started the automation and digitalisation of water treatment plants (GTP) and barriers for the optimal management of groundwater remediation systems. A 24-hour control room in San Donato Milanese remotely monitors 25 out of 42 installations and ensures that the following objectives are met:

 

  • reliability and performance analysis
  • increased level of security
  • control standardisation
  • savings in utility and reagent consumption.