Population equivalent

Industrial water treatment

ACCIONA was awarded the contract for the design, construction, equipment supply, assembly and commissioning of the Oria Medio wastewater treatment plant in Aduna (Gipuzkoa).

The plant has a flow rate of 28,080 m3/day, increasing in rainy weather to 128,000 m3/d, serving a population equivalent of 115. 317 corresponding to the municipalities of Legorreta, Amezketa, Abaltzisketa, Baliarrain, Orendain, Ikaztegieta, Alegi, Altzo, Belauntza, Ibarra, Tolosa, Hernialde, Anoeta, Irura, Asteasu, Zizurkil, Villabona, Aduna and Andoain, including industrial wastewater.

ACCIONA has already designed and built a dozen wastewater treatment plants in the Basque Country, including Apraitz (Elgoibar), Alto Oria (Legarreta), Ondarrea and Bergara, with a daily flow of nearly 200,000 cubic meters, serving a population equivalent of more than 300,000 people. In addition, it operates and maintains another eight, which treat almost 23,000 cubic meters per day, including those of Munguía or Gorliz.

General Information

  • Entity: Gipuzkoa Provincial Council
  • Location: Aduna, Guipúzcoa
  • Population: 92,247 eq/inhab
  • Flow: 28,080 m3/day

Key points

Technical data

  • Average DBO5: 246 mg/l
  • Head in DBO5: 3919 kg/l
  • Average S.S.T.: 294 mg/l
  • Head in S.S.: 8,263 kg/d


  • Coarse solids well
  • Coarse solids breakdown
  • Raw water pumping
  • Fine solids breakdown
  • Sand trapping - grease trapping in 2 lines
  • Distribution pit
  • Primary settling in 2 units
  • Storm abatement tank 1 unit
  • Primary sludge pumping
  • Flow metering
  • SBR biological treatment
  • Excess sludge pumping
  • Primary sludge thickening
  • Biological sludge floater
  • Sludge digestion
  • Filter press sludge dehydration
  • Centrifuge sludge dehydration
  • Sludge silo storage
  • Ancillary services
  • Electrical equipment
  • Control equipment
  • Control, Storehouse – workshop and Staff Buildings

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