De Watergroep




De Watergroep is a Belgian drinking water utility with 62 production plants, supplying 2.8 million customers. About 25% of its drinking water is produced from surface water. Over the last years the company had to cope increasingly with the consequences of eutrophication in rivers and lakes, leading to excess algae bloom and operational problems in the drinking water production facilities.

Cost-effective reduction of phosphorus input

De Watergroep feels the need to invest in more knowledge on cost-effective reduction of phosphorus from surface water in problem areas, to prevent algae blooms and the related water treatment problems.

Repurposing of water treatment by-products for phosphorus sorbing purposes

In addition, the repurposing of drinking water treatment by-products, i.e. iron sludge pellets, as filter material would mean an innovative closed-loop application. These sludges show phosphorus sorbing capacities, but in its original form they are not suiteable for use as filter material.In collaboration with VITO, these sludges are pelletised into stable granules or pellets, with improved strength and adsorption properties.This will lower the total cost of ownership for the innovation, allowing to keep a low price for the drinking water paid by the public.

Role in the NuReDrain project
The main role in the project NuReDrain is linked to the field scale evaluation of a phosphorus filter system.
• The design, building and start-up of a pilot scale filter configuration at one of our largest drinking water production sites.
• The daily follow-up and evaluation of the technical and the quality performance of the filter system.
• Providing saturated filter materials to other partners (VITO and PCS) for fertilizer tests.
• Technical-economical evaluation of upscaling.

Tests at 'De Blankaart'

‘De Blankaart’ is one of De Watergroep’s largest production facilities, where surface water is treated to high drinking water standards.


In 1972 De Watergroep built a large reservoir with a surface of 60 ha (see picture). This reservoir can hold 3 million m3 of water and acts as a buffer for evening out qualitive as well as a quantitative variations.

The reservoir is mainly fed in autumn and winter from the river Ijzer en other surrounding surface water streams, because of high availability and good quality in this season.

During the summer, the surface water quantity and quality is limited, mainly due to runoff from agricultural waters. Therefore the water stored in winter is used for drinking water production in summer.
The filter material(s) will be tested on raw wastewater from the buffer reservoir in order to remove excess phosphorus and prevent algae blooms in the reservoir during summer.