In this stage, the water is treated with chemical reagents to reduce the amount of unwanted compounds and the algae and bacterial load, to improve efficiency in the next stage.

The DWTP uses chlorine, ozone and chlorine dioxide as oxidant agents and disinfectants.

During this stage, organic material dissolved in water and suspended solids are reduced. This is carried out in two stages:

• Coagulation and flocculation: the process that destabilises particles to produce floccules by adding chemical reagents as coagulants and flocculants.
• Decantation: the process by which the floccules are separated from water by gravity in the decanters, obtaining clearer water at the top and clarification sludge at the bottom. This sludge is then treated on the sludge line.

This is treatment with ozone is used to break down organic micropollutants to facilitate adsorption in activated carbon filters.

This consists of running the water through filters containing carbon, a material whose porous surface means it retains pollutants that have not been eliminated in previous stages of the treatment process.

After flowing through the filtration system, consisting of 12 granular activated carbon units, the water has adequate organoleptic characteristics.

At the end of the process, chlorine is added to maintain disinfection throughout the distribution network and ensure water reaches the supply point in perfect condition.

During the decanting process, sludge is obtained that precipitates at the bottom. This sludge undergoes treatment where first it is concentrated in a thickener and then dewatered in a press filter to be removed by an authorised manager.