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Field trials for ‘Application of drinking water sludge for phosphorus fixing’ project

Iron and lime sludge applied to test plots in Bloemkampen nature area

Since 27 August 2015, a Natuurmonumenten information board at the Bloemkampen nature area (municipality of Nunspeet) tells visitors of the research, within TKI Water Technology, into the use of drinking water sludge for phosphorus fixing in the area. In easily understood language the board explains how important low-fertility soils are for the development of flower-rich meadows; and that former agricultural land, such as in Bloemkampen, because of its high phosphorus concentrations, needs to be rendered suitable for nature development.

Drinking water sludge as alternative to excavation

The information board is part of the TKI research ‘Application of drinking water sludge for phosphorus fixing’ project. Under KWR supervision, the project’s test plots, made available by Natuurmonumenten, are treated with iron sludge and iron-lime sludge supplied by Vitens. Researchers expect that the iron will bind to the phosphorus in the soil, thereby reducing the availability of phosphorus: a condition that favours an increase in plant diversity. If successful, this technique could offer an alternative to the costly and not always desirable excavation of the phosphorus-rich top layer. Besides the cost-saving, the technique would create a new application for the waste sludge residual from drinking water production.

Several experiments

Besides Bloemkampen, similar experiments were conducted in the vicinity of Heeze (Brabant Water site), Liempde (Brabant’s Landschap site) and Onnen (Groninger Landschap site). The research focuses on the technical aspect, that is, examining the most effective way of introducing drinking water sludge into the soil. In the summer of 2016, the effects of the treatment on the soil chemistry and vegetation will be determined so that its success can be assessed.

Proefvlakken in natuurgebied Bloemkampen behandeld met ijzer- en ijzerkalkslib