Reclaimed water to face drought

The planet can't wait.

Oliver Thansan
Oliver Thansan
21 March 2024 Thursday 10:22
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Reclaimed water to face drought

The planet can't wait. Climate change manifests itself through water and alters its natural cycle. Heat waves, floods, drought episodes and rising sea levels are intensifying as signs of a climate crisis that has become humanity's greatest challenge in the 21st century.

This year, on World Water Day, under the motto “Water for Peace”, the United Nations reinforces the need to preserve a resource for peace and guarantee a prosperous and stable future. In this sense, more than 2.2 billion people still do not have access to safely managed drinking water, and approximately half of the world's population suffers from a severe episode of water scarcity at least part of the year. Absolutely everything depends on water: from public health to industrial, agricultural and livestock activity, as well as the sustainability and survival of numerous species and ecosystems.

In Catalonia, we find ourselves in an emergency situation due to the lack of rain in the last three years. The reservoirs in the internal basins are below 15%, the limit established by the Catalan Water Agency (ACA) to activate the state of emergency in which we have been immersed since February 1. This drought is not a one-time crisis. The ACA estimates that the water deficit of the Barcelona metropolitan area by 2027 will be 130 cubic hectometers, if measures are not taken immediately.

To face this situation, Aigües de Barcelona has been adapting its daily operations for some time, from the transformation of its facilities to the commitment to alternative water resources such as regenerated water, to guarantee water supply in any circumstance. This is water from the sanitation network that, once purified, receives additional treatment so that it can be reused for various uses, following a circular economy model.

In 2023, Aigües de Barcelona regenerated up to 57.9 cubic hectometers of treated wastewater, a figure that is equivalent to the water consumed by around one and a half million people for a year. Extending this regeneration is the best guarantee to make the metropolitan area more resilient in the face of water scarcity, a solution that has an energy cost up to three times lower than that of desalinating water and that generates a carbon footprint practically half that of water. desalinated.

Currently, the company drives up to 1,500 liters of water per second from the Water Regeneration Station of the Baix Llobregat treatment plant upstream of the Llobregat River to a point, located in Molins de Rei, where it is added to the flow of the river in water condition. pre-drinkable Eight kilometers downstream, this water reaches the collection point of the water treatment station (ETAP) of Sant Joan Despí, and is treated and made drinkable again to later be sent to metropolitan homes. Giving a new life to water following a circular model is key to guaranteeing supply in the metropolitan area.

To have more water resources, the company is committed to reproducing this model in the Besòs basin through a project that has the endorsement of the Generalitat, the ACA and the Metropolitan Area of ​​Barcelona (AMB). Under the umbrella of the European Union's Next Generation funds, the project is valued at around 1.5 billion euros. This investment would allow us to stop depending on rainwater and guarantee the water resilience of the 5 million inhabitants of the Barcelona metropolitan area. The drought shows the importance of collaboration between the different actors in society to face this challenge.

In the Besòs area, the company has completed the works of the first phase of the Besòs DWTP to recover the Rec Comtal as a resource for supply. It also plans to expand its facilities to take advantage of water directly from the headwaters of the Rec and also from the river, which, together with the construction of new wells, will multiply by three the production of drinking water from the DWTP to supply the supply network. using advanced treatment techniques such as ultrafiltration and reverse osmosis. This will mean a water contribution of 15% of the current total consumption in the metropolitan region.

Furthermore, with the aim of providing greater resilience and robustness to the Sant Joan Despí DWTP treatment system, the company has launched an installation to directly connect underground water with the ozonation treatment line and filters. active carbon. This action allows the water of surface origin to be completely separated from that of underground origin in the plant treatment process, reserving the ultrafiltration and reverse osmosis stages for the treatment of river water, and the ozonation treatment line and filtration filters. active carbon for underground water. Furthermore, to guarantee that this groundwater can be treated in the plant's carbon filters without them rapidly losing effectiveness, the filter material has been renewed.