Gravel with an iron coating – originating from the iron removal filters of drinking water companies – has been used on a project basis for several years to remove phosphate from water. By binding phosphate, the growth of blue-green algae is significantly reduced, as is the formation of harmful toxins. The effectiveness of this approach has been proven. The question now is how these successful applications can be scaled up to structural use in waters where blue-green algae regularly occur.
To answer this question, Mara van Heerwaarde conducted market research and spoke with potential users. This resulted in valuable insights and has already led to the first concrete follow-up steps.
From Project-Based Use to Structural Application
The iron-rich filter gravel, with a grain size of 0.5–4 mm, becomes available at drinking water companies when iron removal filters are replaced. AquaMinerals collects this material at a central location in the Netherlands, after which it is washed and sieved in batches. This process results in a standardised product: iron-rich filter gravel 0.5–4.
In recent years, the product has been successfully applied in projects such as De Groote Meer, Lake Paterswoldsemeer, Zwemlust, and in the treatment of drainage water from agricultural and bulb-growing areas. These applications have demonstrated that the material removes phosphate from surface water very effectively, even at low concentrations. This structurally eliminates an important precondition for blue-green algae blooms.
Mara joined AquaMinerals in September as an account manager and has since focused her energy on this subject. “How great is it that we can use a circular residual material from drinking water production to address such a persistent water quality issue,” says Mara. In her research, she mapped problem locations, types of water bodies and the responsible managing authorities. It appeared that 103 designated bathing waters in the Netherlands have experienced problems with blue-green algae. She also examined existing alternatives. “These are often costly, environmentally burdensome or involve undesirable side effects, such as pH changes or the release of other substances into the water.”
The main challenge proved to be reaching the right stakeholders. By actively approaching water managers and engaging in dialogue, a mix of new and renewed contacts emerged. Interest in this circular approach to combating blue-green algae is high, particularly due to the origin of the material and the possibility of regenerating the used iron-rich filter gravel.
This has already resulted in several new orders and concrete applications. It has also become clear that the method of application differs per location and that tailor-made solutions are essential. The goal is therefore not maximum volume, but maximum effectiveness.
In the coming period, Mara will focus on monitoring ongoing applications and further strengthening the network within the value chain. “Wouldn’t it be great if, over time, we could organise blue-green algae control in a structural and standardised way using this sustainable and circular product?”
Would you like to know more? Please feel free to contact Mara van Heerwaarde.