Nieuwegein test winning
In Nieuwegein, from a consortium of companies (KWR, IF Technology, Delft University of Technology, Vitens, Brabant Water, Waternet, Wavin and Visser & Smit Hanab), the first full-scale HDDW was built. The purpose of this full-scale test was to investigate the best method for applying a horizontal filter for (drinking) water extraction. During the test, different types of filter tubes were investigated:
- Stainless steel wrap wire filter
- RVC winding wire filter
- PVC closed filter
- PVC closed filter with an artificial gravel pack
After realization of the filter tubes, it was examined what amount of the withdrawn capacity from what type of filter came. Conclusion: the winding wire filters have a better capacity compared to the closed filters. Traditionally, in the application of vertical filters, drilling fluids are not (or at a minimal) used. After the application of the filter in the drilled hole, this allows the water to flow ‘undisturbed’ into the filter. A horizontal filter cannot be constructed without the use of drilling fluid. This can be an organic or a bentonite clay drilling fluid. The disadvantage of the organic drilling fluid is that there is now a lot of food for bacteria in the soil, that cannot be removed completely. Research has shown that it is possible to built a filter with a very good capacity. However, the bacteriological characteristics of the water are so bad that it cannot be used for the preparation of drinking water. In Nieuwegein we made use of bentonite drilling fluid. This drilling fluid has been removed during the development of the filter. After only two days of developing, the lower limit of the calculated capacity was reached. Also, the extracted water was proved (bacteriologically) completely reliable. Now the test mining is realized, a horizontal filter is also available for further research about sustainability of filters and its effects on the surface.