Population equivalent

Located in Seville

ACCIONA manages the contract to operate, maintain and conserve the wastewater treatment plant of Mairena and El Viso del Alcor. This WWTP - built by the ACCIONA-SANDO joint venture in 2004 and operated by ACCIONA at various stages - has a design flow of 9,220 m3/day and is designed to serve a population equivalent of 41,000 inhabitants.

Among the new features included in the contract is the implementation of a photovoltaic plant that will cover around 30% of the energy consumption of the facilities with renewable energy, as well as the installation of a new centrifugal decanter and an overflow control system equipped with a screening system. In addition, among other efficiency improvements, ACCIONA has included in its bid the implementation of an intelligent system, developed in-house, to control the aeration of the biological process called Biocontrol-Carr®. Its use will result in additional savings in the supply of oxygen to the biological treatment.

General Information

  • Project: WWTP Mairena and Viso.
  • Entity: EMASESA.
  • Location: Mairena and Viso del Alcor, Seville. Spain.
  • Design flow: 9,220 m3/day.
  • Population: 41,000 inhabitants

Key points - treatment


Large particle screens, sifting, desander, sand classifier, deoiler and influent flow metre

Secondary treatment:

Biological treatment of active sludge with nitrification-denitrification and stabilisation of sludge. O2 input / Mud recirculation / Sedimentation

Mud treatment:




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