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CASE STUDY: Water Treatment – Reverse Osmosis (RO) Desalination

May 28th, 2018

How Acciona Agua successfully treated its existing scales whilst ensuring a low impact on the environment.

Case Study: Water Treatment – Reverse Osmosis Desalination

Acciona Agua’s seawater desalination plant “La Tordera” (Blanes) is located in Girona, Spain. This pilot plant contains various technologies currently used in full scale desalination plants and is Acciona Agua’s main global R&D test facility for their global Reverse Osmosis desalination developments.

Process description:
  • Sea water from the open intake (pre-filtration via disk filters) enters the pressurised ultrafiltration system (outside-in dead end hollow fiber UF). The filtered water is stored in a break tank which supplies the RO system and provides backwash water for the UF operations.
  • The pretreated water passes through cartridge filters and enters the Reverse Osmosis system. The RO pilot system is equipped with a single 8″ pressure vessel fitted with 8 modules.

Control CaCO3 and CaSO4 potential scale with a low or phosphonate-free antiscalant, and fully prevent Reverse Osmosis Membrane scaling during inline operation at high recovery rate.


In order to find an innovative and effective solution, Acciona Agua decided to partner with BASF Water Chemicals.

Sokalan® RO 100 was selected as optimal to pilot trial on Acciona Agua’s seawater desalination plant. This aqueous solution of a polycarboxylate with a low molar mass, is a broad spectrum antiscalant designed to inhibit inorganic scale formation in membrane processes.

Sokalan RO 100 antiscalant offers a variety of performance and application benefits:

  • Inhibits RO membrane scaling caused by the following:
  • Calcium carbonate (CaCO3)
  • Calcium sulfate (CaSO4)
  • Barium sulfate (BaSO4)
  • Dispersant qualities reduce colloidal and silt fouling of membrane surfaces.
  • Compatible with the thin film composite (polyamide) and cellulose acetate RO membranes of the leading manufacturers.

BASF’s solution consisted of dosing Sokalan® RO 100 at 0.24ppm, over the 3-month trial period no other chemicals were dosed. Sokalan® RO100 is based on BASF’s polycarboxylate chemistry to avoid scale and protect RO membranes and is ANSI/NSF Standard 60 Certified for Potable Water.


Acciona Agua was very satisfied with the Sokalan® RO 100 test results and this product is now approved for use in Acciona Agua sea water desalination plants worldwide.

Need further information or technical assistance? Contact us today!


About BASF Water Chemicals’ Sokalan® RO line of products:

BASF Water Chemicals has a large portfolio of both standard and speciality scale inhibitors that have been designed with full consideration for sustainability; and they will have a low impact on the environment whilst effectively treating commonly existing scales.

Sokalan RO Types does contain low (RO 100, RO 3500) or no (RO 400) phosphorus, and therefore does contribute less to eutrophication and the associated increase in algal growth in aquatic environments.

Application and benefits

  • Outstanding scale-inhibiting performance
  • Compatibility with major available membranes
  • Low environmental impact (no phosphorus content or low phosphorus content in the products)
  • Longer operation time of RO desalination plants without cleaning
  • Reduced production costs and higher output