The Hard-Hofsteig UWTP Hybrid™ Process, Case Study Austria

  • Bogdanka RadeticEmail author
Living reference work entry


The Hard-Hofsteig used water treatment plant was built in its original form in the 1970s. However, population growth and increasing demand for more extensive nutrient removal then led to plant expansion. The first plant enlargement was carried out in 1997, but for the second, which was planned for completion between 2012 and 2014, insufficient space was available. Therefore, in order to solve this problem, a two-stage hybrid concept was selected. This is a patented, two-stage activated sludge process for extensive nutrient removal, which consists of a high-loaded first stage and a low-loaded second stage, with a combination of two sludge cycles for enhanced nitrogen removal.

This case study considers the upgrade of the Hard-Hofsteig UWTP, which doubled its capacity through the employment of the hybrid concept without any alteration of the plant footprint. In fact, plant capacity was increased from 170,000 PE to 270,000 PE at very low cost, and operational data analyses indicate stable performance.



Biological oxygen demand


Chemical oxygen demand


Kilowatt electric


Ammonium nitrogen


Nitrate nitrogen


Population in 1


Population equivalents in l


Total number of inhabitants and population equivalents in 1


Sequencing batch reactor


Sludge dewatering effluent


Total nitrogen


Total phosphorus


Used water treatment plant


  1. DWA-M 363 (2010) Herkunft, Aufbereitung und Verwertung von Biogasen. © DWA Deutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e. V., Hennef 2011Google Scholar
  2. Ehgartner J, Grabner A (2003) Kostenentwicklung / Investitionskostenanalyse von Kläranlagen in der Steiermark. Diplomarbeit eingereicht am Institut für Siedlungswasserwirtschaft und Landschaftswasserbau der Technischen Universität GrazGoogle Scholar
  3. European Patent EP-0-527-123-B1 (1992) Activated Sludge Process for Wastewater TreatmentGoogle Scholar
  4. Matsché N, Winkler S (2014) The 2-stage hybrid approach for AS-Plants: plant adaptation with minimal space requirements, Poster, 100 years of activated sludge, Essen, June 2014Google Scholar
  5. Radetic B, Gasser M, Winkler S, Matsché N (2016) Enlargement of Hard-Hofsteig treatment plant from 170,000 PE to 270,000 PE in the existing footprint. Water Pract Technol 11(1):210–218CrossRefGoogle Scholar
  6. Winkler S, Matsché N (2008) Das Hybridverfahren – Grundlagen und praktische Erfahrungen. Wiener Mitteilungen 208:115–134. Copyright © 2008; Institut für Wassergüte / TU-WienGoogle Scholar
  7. Winkler S, Gasser M, Schättle W, Kremmel P, Kletzmayr P, Matsché N (2008) Upgrading of wastewater treatment plants for nutrient removal under optimal use of existing structures. Water Sci Technol 57(9):1437–1443CrossRefGoogle Scholar

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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Faculty of TechnologyNovi Sad UniversityNovi SadSerbia
  2. 2.Civil Engineering and Water ManagementUniversity of Natural Resources and Life SciencesViennaAustria

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