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23 Much more fresh water is required for the production process, says Niels Groot, a water specialist at Dow Benelux in Terneuzen (NL): 'Many chemical reactions require a high temperature, after which everything has to cool down again. That's a matter of the smart exchange of heat and using cooling towers,' he explains. Fresh water is needed for those cooling towers. Dow is now pumping about a quarter of that water out of the Biesbosch nature area, which is more than a hundred kilometres to the north. 'But we want to stop doing that,' says Groot. 'There is not enough fresh water there and we don't want to compete with the demand for drinking water. In recent years we have seen how climate change is having effects such as groundwater depletion. We must reduce our water footprint. That is why we are trying to use as many local water sources as possible.' Dow in Terneuzen is already doing a lot to re-use water. But improvements are always possible. For example, by storing rainwater underground instead of draining it to the Western Scheldt. Deltares is helping. 'Their researchers have extensive expertise in this area: which type of subsurface is suitable and how you can store water there,' says Groot. Recently, suitable locations with 'sandy' soil have been identified between Terneuzen and the Belgian border. In addition, Deltares has de- tected freshwater lenses using electromagnetic measurements froma helicopter (the FRESHEM project). In the future, these lenses can be used for water storage. This is done by infiltrating fresh water and, at the same time, raising the water table or by pumping away salt water from below. One of the five specific locations that have now been identified will soon be selected for the follow-up project. Dow also wants to involve local farmers. 'They have to give permission for the storage of the water under their land. And theymay be interested in this development themselves,' says Groot. He expects the water to be available for Dow in about two or three years fromnow. 'We have to invest now but it will save us money in the long term.' HOWDOW IS REDUCING ITSWATER FOOTPRINT Dow is one of the largest chemical companies in the world. It produces plastics and base chemicals for use in, for example, food, paper, pharmaceuticals, cosmetics, packaging and paints. DIFFERENT CIRCUMSTANCES, DIFFERENT SOLUTIONS There are several Dow locations where supplies of fresh water are inadequate. In Leipzig, Germany, for example, Dow is working on the construction of a wetland treatment system in the form of a reed bed. Rainwater will be stored here for use later as process water. And the Dow plant in Tarragona, Spain, is experimenting with working up contaminated process- water flows, for example, for use as 'feed water' in the cooling towers. For more information: tobias.mulder@deltares.nl DELTARES, OCTOBER 2019 BY THESSA LAGEMAN KNOWLEDGE IN OPERATION An alliance between Deltares and the business sector is producing innovative techniques and creating new market opportunities for enterprises.