Delta Life 12

22 Deltares is investigating the cleanup potential of soil bacteria in our geochemical microbiological laboratory. C leaning polluted soils is a costly and time-consuming business. It is not always possible to remove the soil because of the geographical location and the depth of the pollution, in combination with the enormous impact that these operations can have on the inner-city environment. The solution adopted in the 1990s was to pack in the contaminated soil and to pump up the ground- water, clean it and tomonitor it on a permanent basis. A better approachmust be possible. For some time now, Deltares has been conducting studies at our geochemical microbiological laboratory to see how soil bacteria convert contamination 'anoxically' (without oxygen) into harmless substances. A lot of fundamental research has been done with these 'scavengers' but Deltares wants to take the next step: application in practice. Researchers are feeding the bacteria with various substances in the laboratory. The underlying research questions are: how can we improve their living conditions in the soil and in which conditions do they performbest? Deltares wants to use this knowledge to condition the bacteria to do their dirty work as well as possible. Natural conditions are always different from those in the laboratory. That is why Deltares is also conducting field trials, for example in Grift Park in Utrecht. What works in the lab? Will it work in the field? Researchers are using soil bores and groundwater samples to examine the local situation. Ultimately, this research is intended to result in a natural cleaningmethod for polluted soils and groundwater. There are numerous potential applications: the remediation of former industrial sites or cleaning work in the chemical and petrochemical industries. For more information: johan.vanleeuwen@deltares.nl BACTERIA THAT DO THE DIRTYWORK Stirrer Data logger Sampling point for gas phase Bioreactor BY ASTRID VAN BRAGT-SCHOL TESTING GROUND