International Journal of Environmental Research

, Volume 13, Issue 6, pp 1005–1013 | Cite as

Assessment of Enhanced Biological Phosphorus Removal Implementation Potential in a Full-Scale Wastewater Treatment Plant in Croatia

  • Tanja ŠikićEmail author
  • Laurens Welles
  • Francisco Javier Rubio-Rincón
  • Marin Matošić
  • Damir Brdjanovic
Research paper


The objective of this study was to assess the possibility of retrofitting an existing full-scale wastewater treatment plant (WWTP) based on a sequencing batch reactor (SBR) technology with the enhanced biological phosphorus removal (EBPR) process. Wastewater characterisation showed highly variable influent composition that fluctuated throughout the year with a rather low and unstable SBOD/TP ratio (SBOD—soluble biological oxygen demand; TP—total phosphorus), which is considered unfavourable for EBPR. Characterisation of the sludge showed that the non-EBPR SBR sludge from the WWTP Koprivnica contained no detectable phosphorus accumulating organisms (PAO), but could be transformed in a laboratory into EBPR performing sludge in less than 45 days under favourable conditions for PAOs. The microbial community composition was assessed using an FISH (fluorescence in situ hybridization) analysis, which confirmed that the original sludge from the WWTP, which did not have detectable PAOs, was transformed into the sludge enriched by PAOs belonging to the genus ‘Candidatus Accumulibacter phosphatis’ after 43 days of cultivation. A plant retrofit, based on the results of laboratory experiments, was proposed with the enrichment of the wastewater with volatile fatty acids via primary anaerobic fermentation and step feeding. Results of mathematical modelling (BioWin) showed that such strategy could lead to sufficient P removal through EBPR in this WWTP.

Article Highlights

  • Wastewater composition was unfavourable for sufficient P removal by the EBPR process.

  • The current sludge had no detectable PAO.

  • Cultivation of the sludge in laboratory SBR enriched current sludge with PAOs to perform substantial EBPR.

  • Simulations showed that fermentation of the influent in full-scale WWTP could be used to feed the PAO to achieve sufficient bio-P removal.


Enhanced biological phosphorus removal (EBPR) Modelling Municipal wastewater treatment Sludge characterisation 


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Copyright information

© University of Tehran 2019

Authors and Affiliations

  1. 1.Hrvatske Vode (Croatian Waters)ZagrebCroatia
  2. 2.Department of BiotechnologyDelft University of TechnologyDelftThe Netherlands
  3. 3.Department of Environmental Engineering and Water TechnologyIHE Delft Institute for Water EducationDelftThe Netherlands
  4. 4.Faculty of Food Technology and BiotechnologyUniversity of ZagrebZagrebCroatia

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