The pre and sand traps 1-2 of the GALINDO WWTP pretreatment system are in poor condition in the areas of the walls and rolling lanes along which the sand trap bridges move, preventing correct movement and sometimes leading to derailment. .

The gates that control the passage of water to and from the pre- and desanding are at the end of their useful life, present a high degree of degradation due to oxidation with loss of material and do not guarantee the necessary tightness.

The pre and desanding aeration system (aeration by means of a submerged turbine) is not efficient and it is advisable to replace it with aeration using a thick bubble that has been successfully tested in the desander 1.

Challenge achieved: The work must be executed in the shortest possible time, given that it requires the stoppage of fundamental elements (raw water pumps, sieves, pre- and sand traps) in the operation of the GALINDO WWTP.