Starting in 2019, WSP provided RSI with a full set of design services (from feasibility to basic and detailed design for tender for construction) for the new water treatment plant, which is currently under construction.

The new water treatment plant, based on ultrafiltration, double-stage Reverse Osmosis (RO), and Electro Deionization, will provide up to 650 m3/h of demineralized water and 250 m3/h of soft water to the users of the site. The new plant will minimize the water footprint of the petrochemical site, as the water source could be 75% surface water and up to a maximum of 25% treated effluent from the inorganic wastewater treatment plant of the same petrochemical site. Brines from the first stage RO will be reused in the firefighting network, while the final brine of RO will be discharged to the main wastewater treatment plant of the petrochemical site and then into the sea.

The design was made according to WSP’s Future Ready™ approach as follows:

• Provision of a suitable modularization of the plant in multiple lines to cope with changing/evolving treated water demand.
• Building the new water treatment plant inside the same building as the existing one, revamping it for the specific purpose. Therefore, a temporary containerized solution is being utilized to provide demineralized water to the petrochemical site while the old equipment inside the existing building is being dismantled and the new ones installed.
• Incorporating the minimization of CO2 footprint into the design from the beginning, as a decision tool to guide the selection of membrane-based solutions versus ion exchange resins. It was verified that the saving in CO2 emissions associated with chemicals, which will no longer be needed with the new configuration, will more than offset the higher power consumption required by the membrane-based solution.

With the new water treatment plant, the petrochemical site will be ready for future operations, serving also the new plants which have been and are being started up. Eni Group has plans in Ravenna to further expand the production mix of highly specialized elastomers, in particular thermoplastic rubbers, polybutadiene, and SBR intended for the tire and automotive sectors, which are undergoing strong development and transformation.

How we made a difference along the different design phases

WSP was brought on board in 2018 when there was only an idea of possibly replacing the water treatment plant of the industrial site. The initial feasibility stage allowed us to prove the concept of the applicability of the solution to the specific case and to introduce sustainability criteria in the evaluation of the process alternatives. The outcome of this phase was the confirmation of the membrane-based process train as the one with the lower CO2 footprint.

The subsequent basic design allowed the consolidation of the conceptual design and brought the idea of the temporary water treatment plant solution to allow the reuse of the existing building for the location of the new membrane-based units. Moreover, the investigation of water quality needs for the firefighting network, as well as the treated effluent quality of the inorganic wastewater treatment plant, allowed the identification of the final solution with relevant water saving and a significant decrease in the water footprint of the petrochemical site.

The final detailed design incorporated all the local codes and legislative requirements as well as the proper packaging to allow the client to properly execute the tender for construction.

Keeping high design quality and performance under difficult circumstances

A relevant part of the design was performed under the restricted working conditions of COVID; however, the WSP design team was able to provide proper delivery and maintain the schedule even in those peculiar conditions.