Expansion of the Campo de Dalías desalination plant: Ensuring Almería’s economic and social sustainability

The Almerian region of Campo de Dalías, including its major town El Ejido, is renowned for having one of the highest concentrations of greenhouses globally. Since the 1980s, Almería in southern Spain has developed the largest concentration of greenhouses in the world, covering 26,000 hectares. The greenhouses reflect so much sunlight into the atmosphere that they are cooling the province according to recent research. This high-value agricultural system requires substantial water, and its rapid expansion in recent decades has increased the need for additional resources.

The Campo de Dalías desalination plant, built in 2015, uses reverse osmosis to produce potable water. Seawater is collected through a 1.6 km pipeline and undergoes pre-treatment with 40 dual-layer filters. It then goes through a two-step reverse osmosis process: the first step recovers up to 95% of the energy, while the second reduces boron to less than 0.5 mg/liter, making it suitable for agriculture. In the post-treatment phase, the water is re-mineralized and disinfected to ensure it is fit for human consumption and irrigation. The treated water is distributed via a 41 km underground pipe network, and brine is discharged into the sea through a 2 km pipeline with diffusers designed to minimize environmental impact.

Despite being one of Europe’s largest desalination plants, Campo de Dalías can no longer meet the growing water demand. With a current production capacity of 97,200 cubic meters per day (30 million cubic meters per year), it supplies irrigation for 8,000 hectares of greenhouses and provides water to nearly 300,000 people in the municipalities of El Ejido, Vícar, and Roquetas de Mar. To address the rising demand, the central government plans to expand the plant’s capacity to 129,600 cubic meters per day (40 million cubic meters per year).

The public utility Acuamed has awarded Ayesa the contract to expand the Campo de Dalías desalination plant, covering all stages from seawater pumping to delivery to farmers’ fields. Leveraging its extensive experience in hydraulic infrastructure, Ayesa will handle marine works adaptation, pre-treatment, reverse osmosis, remineralization, and the installation of a new reservoir for pumping to a lower irrigation level, as well as upgrading the primary irrigation network.

Given the desalination plant’s limited storage capacity, seawater must be supplied in precise quantities to ensure effective desalination and efficient pumping into the irrigation network. To facilitate this, frequency converters have been installed on the seawater pumps, high-pressure pumps, and product water pumps.

Greenhouse agriculture drives the region’s economy, so a reliable supply of high-quality water is essential for its economic and social well-being. The desalination plant employs some of the most advanced technologies available, including a raw water intake system, dual filtration for pre-treatment, reverse osmosis, post-treatment, and facilities for pumping, storing, and distributing the treated water.