Our environmental interventions in Priolo

At the multi-company site, we are engaged in soil and groundwater remediation interventions on our areas and by mandate for the co-located companies.

The most sustainable remediation technologies at the service of the multi-company Priolo site

The multi-company Priolo’s industrial site was established as part of the industrialisation plan for southern Italy promoted after the Second World War, which in eastern Sicily was implemented by setting up plants for refining oil and processing its derivatives. Since its origins, which date back to 1956, the hub witnessed a significant expansion of the oil and chemical sectors, marked by a number of corporate and operative directions. In 1991, following a transaction with Enimont, the Eni group entered the site through Enichem, which acquired the base and intermediate chemical plants as well as the refining facilities from Montedison. A state of environmental emergency was declared during this decade (1990s) and the Priolo site was classified as one of National Priority (1998), with an extension among the largest in Italy, of approximately 5,815 hectares on land and 10,185 hectares at sea, including the port of Rada di Augusta, an important crossroads for commercial shipping in the Mediterranean. Since 2002, Eni's subsidiaries have carried out emergency safety measures and have designed, defined, implemented and managed systems to eliminate contamination, in accordance with the projects and monitoring protocols approved by the ministry of the Environment and other bodies that promote the reuse of treated groundwater, the application of innovative and environmentally friendly technologies, and the regeneration of the areas owned by the group. As of 31 December 2024, we have incurred environmental costs of €701 million for our areas.

Priolo: key elements

A site where we implement our circular strategy for the valorisation of resources.
Remediation and sustainability
Remediation and sustainability

For Priolo’s remediation we adopt an operational approach oriented towards the application of on-site and in situ technologies, minimising the impact of our interventions

Safeguarding of water
Safeguarding of water

The water treated at Priolo’s groundwater treatment plant is demineralised and reused in the production processes and plants at the multi-company hub, with a circular economy approach.

Priolo at a glance

Icona tagLocation: Italy, Sicily
Icona tagStart of the environmental interventions: 2002

Priolo past and present

Site history

Start of the environmental process

In 2001, characterisation activities on the site began, and the following year Eni’s co-located companies began emergency safety measures and remediation designing.

Eni acquires the Montedison group’s assets

Following the Enimont operation, the Eni group entered the site through Enichem, which acquired the base and intermediate chemical plants as well as the refining facilities from Montedison.

Our story

The Priolo Gargallo industrial hub is created

Since its origin, the petrochemical hub has seen a significant expansion, marked by various corporate and operative directions, in the oil refining and derivatives processing sector.

Our activities in Priolo

In Priolo, as we inherited approximately 300 hectares of former Montedison decommissioned areas, we are engaged in emergency safety measure activities and in the design and execution of soil and groundwater remediation interventions. Whenever possible, we have implemented a combination of the most advanced in-situ remediation technologies, tailored to the site's complexity, minimising the environmental footprint of the interventions. In addition to the remediation of our areas, we also carry out environmental procedures on behalf of other companies. At the site, we manage the remediation of surface and deep groundwater, also on behalf of other Eni companies, using a system of hydraulic barriers and a groundwater treatment plant (GTP), among the largest in Italy, with a capacity of 600 m³/h. Experimental activities for the verification of the technologies envisaged in the deep aquifer remediation project, currently under preliminary investigations, are ongoing. The status and progress of the aquifer remediation, as well as the effectiveness and efficiency of the treatment systems, have been monitored since 2016 through the Single Monitoring Protocol approved by the authorities. Regarding the decommissioning of the disused facilities, we have completed waste removal and the demolition of the Dichlorethane (DL1), Alkaline Carbonates (CS9), and Propylene Oxide (PO) plants. The project for the demolition of the Chlor-Alkali plant, is under preliminary investigation.

Status of the environmental process

Starting from 2003, Eni's environmental company has submitted soil and groundwater remediation projects, some of which obtained authorisation by ministerial decree and are ongoing, while others are currently undergoing preliminary investigations.

Sustainable remediation solutions

The areas south of the Vallone della Neve at Priolo’s site cover a total of approximately 196 hectares, of which around 26.8 are “non-compliant”. For soil remediation, following the top-soil removal intervention, we are applying the most advanced in-situ technologies aimed at treating contamination directly in the environmental matrix, including ISCO (In Situ Chemical Oxidation), TPE (Two Phase Extraction) with thermally assisted vapour extraction, Soil Flushing, and ECRT (Electro Chemical Remediation Technology). Following the interventions already completed, approximately 21.5 hectares can be released. In Area B3, we are also carrying out soil remediation using the Soil Vapour Extraction technology, while for the aquifer, the Permeable Reactive Barrier (PRB) technology is being applied on a pilot scale.

Water resource management

Priolo boasts the second-largest groundwater treatment plant (GTP) in Italy amongst the ones we own, with a nominal flow rate of 600 cubic meters/hour. The remediated groundwater is recovered through an osmosis process and recirculated in the production processes and plants. To this end, we have installed two demineralised water production lines within the GTP’s groundwater treatment supply chain. The osmotic water produced is partly reused on-site and partly sold to third parties, allowing for reduced withdrawal from nature.

In recent years, we have also implemented a new Dynamic Control System, which enables real-time interventions on certain processes. This system allows the plant to operate under ideal conditions, minimising variances in operating parameters, limiting the environmental footprint in terms of lower energy consumption as well as reagents and waste produced, while simultaneously increasing permeate production by 13%.

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