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08/08/2014 | Multibore® membranes from the BASF subsidiary inge® improve water treatment

Seas and oceans are the biggest water reservoirs on Earth. Since decades sea water is turned to drinking water by desalination in large scale. In Ghana, West Africa, a modern desalination plant is currently being established to produce  up to 60,000 cubic meters of drinking water per day – enough to supply half a million people. In this plant ultrafiltration membranes made by the BASF subsidiary inge® play an important role: They are used to pretreat the salt water in order to optimize the actual desalination and to protect the downstream salt filters from contamination. These salt filters operate according to the reverse osmosis principle – hereby the water diffuses as individual molecules through the sensitive membrane. As high pressure of up to 80 bar is required for this process, the pre-purification by means of ultrafiltration additionally contributes to the limitation of the energy input.

The water taken out of the sea is forced under pressure through the very fine-pore Multibore®  membranes and can pass through them, while undesired substances such as sand, clay, algae and even pathogenic germs are intercepted. At first glance, the ultrafiltration membranes look like thin white tubules, but the cross-section reveals their complex inner life: The fiber contains seven capillaries into which the raw water runs. The walls of the capillaries have tiny pores with a diameter of about 20 nanometers – this is 500 times thinner than a filament of a spider's web. All the particles larger are retained here by the membrane. Only the purified water passes through the pores into the plastic fiber and emerges again on the outside of the fiber.

Production of the membranes requires extensive know-how and experience. “The challenge is to create pores during the production process that are small enough and evenly distributed over the membrane surface,” explains Dr. Nicole Janssen, Laboratory Team Leader at Performance Materials Research. Together with her team, she is optimizing the conditions and the starting material from which the membrane fibers are manufactured: the BASF plastic Ultrason®  E, a polyethersulfone. 

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Econsense

Forum for Sustainable Development of German Business e.V.

econsense is an association of leading, globally active companies and organisations of German business specializing in the area of sustainable development and corporate social responsibility (CSR). Founded in 2000 on the initiative of the Federation of German Industries (BDI), the goal of econsense is to provide a dialogue platform and think tank, with the dual objectives of advancing sustainable development in business and assuming social responsibility.