In the Netherlands, will brackish water be the future of drinking water?
Photo credit: Sipa
In The Hague in the Netherlands, the water is so pure that the inhabitants drink it without any treatment. It is even the main ingredient in Heineken beer. Taken from the groundwater located under the dunes of Scheveningen, the neighboring seaside resort, it has been naturally filtered for centuries by the sand from the dunes.
However, under the effect of the demographic pressure that the country is experiencing and the already-visible consequences of climate change, drought and heatwaves, this natural supply is no longer sufficient. There is a solution: producing drinking water by desalinating brackish water, the slightly salty water unfit for human consumption found in abundance in groundwater.
Dunea, a water provider, and Waternet, a public water company, have launched projects to desalinate this water by reverse osmosis, in other words by filtering it under high pressure through a very fine membrane. This technique is already used by Veolia in eight countries, where the group owns desalination plants. In Sur in Oman, for example, its subsidiary SIDEM has built a plant with a total capacity of 110,000 m3 per day, which has been run by Veolia Middle East’s local subsidiary since 2016.
Dunea will desalinate the brackish water from a bubble of water located beneath the Scheveningen dunes and use the space obtained to store freshwater reserves. This water has the advantage of being better protected by environmental legislation than water from the polders, drained and cultivated land reclaimed from the sea, which have high levels of pollution caused by crop protection products.
In July 2020, this project obtained three million euros of European funding as part of the LIFE program. If it is successful, Dunea will apply its technique all along the Dutch and Belgian coastlines, which have many sites with a mix of freshwater and brackish water.
A test project for the environment
Inland, Horstermeerpolder — a historic polder halfway between Amsterdam and Utrecht — is another pilot area where Waternet is planning to pump underground brackish water. The project, which will cost several million euros over three years, will serve to prove the viability of the brackish water pumping and purification techniques combined with a safe treatment for the brine from the desalination process. All without undesirable side effects for the environment, such as lowering the groundwater level around the wells.
If the tests prove conclusive, Waternet expects to produce three to five million cubic meters of drinking water per year by desalinating up to six million cubic meters of brackish water. The experiment could be exported to other deltas worldwide.
A crucial question remains for both projects: what should be done with the brine from the desalination? For Dunea, this residue can be discharged directly into the sea, provided that the legislation is changed. Waternet plans to transport it to a wastewater treatment plant where it will be cleaned up and discharged into the Amsterdam-Rhine canal, up to the North Sea.
Other solutions exist to reduce as much as possible the impact of discharging concentrated brine into the environment. For example, depending on the site, the Veolia group injects it into deep wells, carries out forced evaporation in confined ponds, or treats it using evapo-concentration.
“Brackish water as a solution to the growing demand for drinking water,” Innovation Origins, October 15, 2020 : innovationorigins.com/brackish-water-as-a-solution-to-the-growing-demand-for-drinking-water/
Desalination: a future-focused environmental solution for Veolia : www.veoliawatertechnologies.com/fr/applications/dessalement