While biodegradable, non-toxic flocculants still form a ‘holy grail’ in the world of water treatment, micro-organisms producing so-called exopolymers already have the recipe for such flocculants at hand. Could we draw inspiration from Nature’s biosynthesis cookbook?

When surface water passes through the soil, it is important to understand how infiltration affects the microbiological composition of the water. Vitens and Deltares have studied how this composition changes during infiltration. This was found to vary considerably between the different types of water.

De Vlot in ’s-Gravenzande in the Netherlands is a cooperative water treatment facility serving more than sixty greenhouse nurseries. The existing treatment plant effectively removes organic matter and plant protection products, but the effluent still contains too much salt. It therefore cannot be discharged into surface water or reused for irrigation. An additional step is required, particularly for the removal of nitrate. A pilot study by REDstack demonstrated that ‘electrodialysis reversal’ (EDR) achieves highly selective nitrate removal: up to 97 percent removal with 75 percent total salt removal and 80 percent water recovery.

Land subsidence in peatlands is mainly due to peat oxidation under aerobic conditions. The primary cause is a lower groundwater level during the growing season, the same time of year when we experience a rainfall deficit (usually April to September). The groundwater level falls in response to evaporation exceeding precipitation, but also due to seepage into nearby deep polders. Raising the water level in existing ditches does little to mitigate this effect.

The Netherlands can continue to protect itself from sea-level rise by raising dykes and reinforcing engineered flood defences. While this approach can maintain flood safety, it often leaves limited room for natural processes that enable coastal and estuarine landscapes to adapt to changing conditions. An alternative is to create adaptive coastal landscapes that can keep pace with sea-level rise through sedimentation and ecosystem development. This article explores where such landscapes already exist, where opportunities remain to restore and strengthen them, and how it they can contribute to future flood protection strategies.

A 2023 study shows that the multi-layer safety approach has yet to gain much traction. This article describes a methodology for adopting such an approach, having been applied to the bifurcation area.

Smart design in the Ketelmeer that includes shallow areas, channels and raised sections creates a natural buffer for flood protection, combined with thousands of hectares of new delta nature. This system-scale solution transforms the area from a vulnerable storm basin into a resilient delta. 

Untreated sewage discharged directly into ditches, streams and canals during heavy rainfall can cause a local deterioration in water quality. What effect does this have on macrofauna (small aquatic animals)? By statistically correlating monitoring data on the occurrence of macrofauna with data on sewage discharge points from the Aa en Maas Water Board, it has been possible to give an initial picture of this impact.