The works covered by this contract include the drafting of the construction project and, in accordance with this technical document, the construction of the projected hydraulic work and the start-up of the new processes. This action is due to the need for the lack of capacity of the current wastewater treatment plant (WWTP) of Sada to give adequate treatment to the wastewater it receives and to ensure compliance with the parameters of discharge of treated water to the receiving environment.

This work completes the necessary actions for the expansion of the treatment capacity of the existing wastewater treatment plant of Sada, without requiring more land than those currently affected and maintaining the purification service during the execution of the work.

The works of the contract include the preparation of the constructive technical document and the execution of the work and its commissioning.

The need for action derives from the lack of capacity, both hydraulic and polluting load, of the current wastewater treatment plant (WWTP) of Sada.

The solution to the situation will increase the purification capacity to 30,463 equivalent inhabitants, with a maximum allowable flow in rainy weather of 181 l / s. To carry out this modernization action, it will be necessary to convert the existing secondary treatment to a moving bed, hereinafter MBBR, which will also involve the adaptation of the other purification stages. In summary, the following is contemplated:

• New distribution box to the pretreatment and general by-pass.

• Expansion of hydraulic capacity of existing pretreatments to 181 l/s.

• Distribution element to the secondary process.

• Conversion of the two biological reactor lines to MBBR.

• Distribution box to the clarification stage.

• Demolition of existing decanters and construction of two lamellar clarification lines.

• Disinfection of treated water and connection to the discharge pipeline.

• Adaptation of the sludge treatment line to the characteristics of the sludge of the new biological purification, with the incorporation of a stage of biological stabilization of the slats and updating of the dehydration.

• Updating of auxiliary facilities (buildings, deodorization, interior sanitation, urbanization and others that correspond).

• Adaptation of the electricity supply to the new needs of the expanded infrastructure.

Once the work is executed, the new processes will be launched in collaboration with the existing municipal purification service until the expected yields are reached.

As it is an existing service, the action must be designed without affecting more surface than that occupied by the existing installation and to keep the treatment plant in operation.

Prior to the construction stage, the contract includes the drafting of the project in which the solution selected in the tender will be developed at the construction level, with the associated administrative procedures.