The water produced when digging the cavern in this project contained a large quantity of solids in suspension, in excess of the levels permitted in our discharge authorization from the Júcar River Basin Authority. The water therefore had to be decanted prior to discharge so as to minimise turbidity.

In order to meet the required parameters, we installed a decanter equipped with a fi lter press capable of treating 324 m3 of dirty water per hour.

The wastewater from the cavern excavation is collected at a number of pumping stations and then pumped to a decanter. The clean water spills over the top of the decanter and then fl ows to the reservoir. The sludge that accumulates at the bottom of the decanter is drawn off through a pneumatic valve into the homogenization tank, which is fi tted with a stirrer to prevent the sludge from solidifying. The homogenized sludge is sent to the fi lter press, which squeezes the water out of the sludge and discharges dry sludge.

The solution has enabled us to improve the quality of the treated water outfl ow considerably, so the water can be sent back to the reservoir which will be used by the Cortes-La Muela plant to produce electricity. Thus, valuable water is fed back into the system.