Population equivalent

Biological treatment of activated sludge in piston flow.

The Baiña WWTP is designed to treat the discharges of a population equivalent of 86,500 inhabitants, with a maximum instantaneous pre-treatment capacity of 2,400 l/s.

It also has biological treatment by means of prolonged aeration and biological nitrogen elimination with a maximum capacity of 700 l/s. The facilities are complemented by a water reuse system for irrigation and industrial washing, a sludge line designed for sludge dewatering by means of filter presses, and a chemical deodorisation system with an air renewal capacity of 29,000 m3/hour.

It has a primary treatment system with three 30-metre diameter circular decanters with a maximum instantaneous capacity of 1,600 l/s, two of which can operate as a storm tank.

General Information

  • Project: WWTP Baiña.
  • Client: Consortium of Water Supply and Purification of Asturias.
  • Location: Mieres (Asturias). Spain.
  • Capacity: 43,200 m3/day.
  • Population: 86,500 inhabitants.

Key points


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

Primary treatment:


Secondary treatment:

Biological treatment of active sludge in the piston flow with nitrification-denitrification. O2 input / Mud recirculation / Sedimentation.

Mud treatment:

Thickener, floater, dehydration and post-treatment.



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