Field Case Venner Bruchkanal: Improved P filter system with iron-coated sand is ready for measurements during new drainage season

19 December 2019 - Published by Charlotte Boeckaert
Since the start of the NuReDrain project, the Lower Saxony Chamber of Agriculture has developed and constructed a filter shaft on an 8.2 hectare field near the Venner Bruchkanal. The filter system collects and filters the nutrient-containing water from a drainage system shortly before it flows into the receiving water. In the past months improvements have been made to deal with clogging due to the presence of ochre flocs.

For this filter, iron-coated sand (ICS) is used as filter material to adsorb P. This filter material is a by-product of the regional drinking water production of the Wasserverband Wittlage. Before and after the P filter, water samples are automatically taken from the drainage pipe every 2.24 hours, 10 times a day.

In the past, the filter suffered from clogging due to the presence of ochre flocs. Therefore a pre-filter has been installed to overcome this problem. Also further optimizations have been done: a cold water insulation was installed to protect the filter system against freezing of water in the pump hoses and therefore data failure. Another modification is the changing of the position of the suction strainer for sampling after the filter. Previously this was done in the drainage pipe, now it is done at the lowest point in the ICS material.