Seawater Desalination Plant for Malta & Gozo

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Seawater reverse osmosis plant to supply 10,000 m³ of affordable drinking water daily

The innovative desalination plant is in the commissioning phase for the Water Services Corporation (WSC) of Malta. The contract, which included design, construction, commissioning, operation and support, was awarded to AST in collaboration with Mekorot – the Israeli National Water Company.

The turnkey solution aims to provide a highly efficient plant which reduces OPEX, minimizes chemical consumption and handling, and offers highly convenient operation. The fully and remotely automated desalination plant is designed for easy access and maintenance without the need for highly trained personnel.

Preserving History and Reducing Environmental Impact

An unusual feature of the project involved renovation of a 60-year-old building to fit the new desalination plant, ensuring it could deliver reliable supply during peak tourism season, while preserving the architecture. AST collaborated with a local architect, Alexander Bigeni, and Vella Construction Services, local sub-contractors who were responsible for construction of the original building some 60 years ago. The company had to meet stringent construction and environmental regulations. Once design was completed, AST began construction and renovation of the actual building, including the outdoor and indoor structures and systems.

The project presented a number of challenges, including completing various phases under the constraints presented by the COVID19 pandemic.

Another key challenge was the installation of pumping intake and outfall under the seabed in rocky terrain, while ensuring the public beach remained clean and operational.

A further challenge involved welding a 450mm polyethylene (PE) high density pipe on a side road near Marsalfon village. To minimize impact on the environment, the Horizontal Directional Drilling (HDD) pipe, designed and built specifically for this reason, was inserted into the Horizontal Drilling Tunnel (HDT) under the seabed and smoothly slid into the sea in the middle of Hondoq bay.

The installation is some 330 meters from the plant enabling brine discharge away from the public beach. Thereafter, mooring took place and a desalination diffuser was installed on the sea bed for safe completion of this phase. A state-of-the-art Pexgol pipe was used to install onshore six boreholes, enabling redundancy and sustainability.

The Seawater Desalination Process

Seawater is pumped from the onshore wells and the feed water is transferred to the adjacent desalination plant, where reverse osmosis desalination takes place. During the post-treatment phase, the permeate water is hardened using an advanced AST design in collaboration with an OMYA lime reactor system. This adds the required hardness without contaminating the water, thereby reducing the environmental impact.

To improve water quality and taste, acid-free calcium is added, decreasing the need for chemicals and reducing haulage of acid and chemicals to the island. Water sanitation is maintained through cost-effective chlorine generation on-site for high quality water, further reducing OPEX and haulage as well as eco-footprint.

The plant has commenced pumping seawater and safely discharging the water into the sea. Following tests and commissioning, the plant was officially opened by Malta’s Prime Minister, Dr. Robert Abelo, on November 19, 2021.

High-quality drinking water, produced by an autonomous SWRO plant, will be delivered to GOZO residents. 

 

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