El Atabal brackish water desalination plant (Spain)

This plant offers a genuine solution in cases of extended situations of scarcity of water resources in Malaga.

El Atabal produces 165,000 m³ of desalinated water per day. The treatment enables the salinity level to be reduced from 6.47 g/l to 0.2 g/l. The installation also offers the possibility of making better use of water from the Guadalhorce dam and of supplying the town with larger quantities.

The brine is discharged into an outfall sewer that is more than 6 km long and is 800 mm in diameter, which routs it to the sea sewer outlet at the Guadalhorce treatment plant. Through the mixing of the two outfall sewers, the environmental impact is reduced.

the desalination process

Salt is removed using the reverse osmosis process, following pretreatment carried out using the clarifiers and sand filters comprising the existing drinking water production plant.

The desalination process was designed featuring two stages : the first stage processes the whole flow rate, while the second stage processes the brine discharged from the first stage (with a double saline concentration), using the same type of membrane. Thus, 80% of the raw water supplied to the plant is used.

Energy recovery turbines and variable speed drives were installed for the feed pumps for the reverse osmosis membranes, thus making it possible to achieve an energy recovery rate of 80%.

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key figures :

• Water :
  • Capacity: 165 000 m³/day
  • Intake salinity: 6.47 g/l
  • Outlet salinity: <0.2 g/l
  • 8,400 membranes instaled
  • Maximum operating pressure: 32 kg/cm²
  • Drinking water production ratio: 80 %

• Energy consumption :
  • 0.72 – 1.19 kWh/m³
  • 119.2 to 196.8 MWh/day
  • Maximum energy produced: 25.6 MWh/day by two Pelton turbo-alternators (680 kW each)