Julio Pérez


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Telephone: +31 15 27 81482
Address: Department of Biotechnology - Faculty of Applied Sciences, Delft University of Technology, Julianalaan 67
2628 - Delft (The Netherlands)
Research ID: www.researcherid.com/rid/A-1468-2009

Position: Guest Professor / Researcher (Marie Curie fellow) at Technological University of Delft (The Netherlands)

Other: Associate professor at Univ Autonoma de Barcelona (Spain)


My background is chemical engineering and (environmental) biotechnology. I initially developed my research career on nitrification in biofilm reactors for life support systems for long-term manned missions in space, a research project of the European Space Agency. After completion of the Ph.D. (June 2001), I spent a postdoctoral period in TU Delft which served for readdressing my research field, towards the use of nitrification in the wastewater treatment field. I obtained a permanent position in Univ Autonoma de Barcelona in 2006, and since then I have been active in research and teaching. I have been involved in different national and international research projects as participant as well as principal investigator.

In November 2013 I received a Marie Curie fellowship GreenN2, to investigate greener biological nitrogen removal: minimization of N2O emissions and optimization of the integration issues of the nitritation / Anammox process for main stream wastewater treatment with Mark van Loosdrecht (TU Delft, The Netherlands).

Major scientific and technological achievements: I developed a procedure for the use of anammox for sewage treatment based on two steps nitrogen removal (DOSIS-cold ANFIBIO), see patents. I developed an automatic control strategy to achieve and maintain full nitritation in biofilm reactors (ANFIBIO) (Bartrolí et al., 2010). The highlights of the technology are mainly three: (i) the high treatment capacity achieved, up to 6 kg N m-3 d-1 yielding low space footprint installations; (ii) the technology is applicable at relatively low temperature (20ºC); (iii) the strategy did not require of low dissolved oxygen concentrations (demonstrated as applicable even at 7 mgO2 L-1). This last aspect is of unique relevance, since the N2O emissions have been detected associated to this type of processes when low dissolved oxygen is maintained in the reactors. Consequently, the technology might be applied minimizing the emissions of these greenhouse gases. The invention was first validated in the laboratory at pilot scale. I received funding as responsible researcher of a technology transfer project. The project aimed to gain the definitive proof of concept of the ANFIBIO technology. The operation of the prototype installed in a municipal wastewater treatment plant (WWTP) in NE Spain (June 2012) demonstrated the possibility of switching from initial SBR operation for granulation of the sludge to continuous model of operation (Tora et al., 2013). The efficiency of the installation was tested for two different targets: (i) low ammonium concentration in the effluent, when the application of heterotrophic denitrification is required (e.g. industrial effluents with high ammonium concentration with doubtable use of anaerobic ammonium oxidation): (ii) oxidation of the 50% of the inflow ammonium concentration for a later anaerobic ammonium oxidation –Anammox- process. Both targets yielded satisfactory results. Additionally, during the operation of the reactor, a close collaboration with another researcher, Maite Pijuan (formerly at University of Queensland, Australia, now at the Catalan Institute for Water Research, Girona, Spain) was established for the measurement of N2O emissions in the prototype. The results demonstrated very low N2O emissions when the reactor was operated in continuous mode at relatively high dissolved oxygen concentrations (Pijuan et al., 2014).

I found an explanation for the division on labour in nitrification, based on the kinetic theory of optimal design of the metabolic pathways (Costa et al., 2006). The idea of this study was born after a short period spent as invited researcher in the University of Bonn (Germany, February 2003). Dr. Jan-Ulrich Kreft was lecturer in that university (now settled in the University of Birmingham, UK). Later, I obtained funding in a competitive program to support emergent research projects led by young researchers. With this funding, I could start the research project between both European universities and additionally enrolled a young graduate researcher (Engràcia Costa, chemical engineer, Univ Autonoma Barcelona, Spain). The funding covered mainly the mobility of the three researchers between Germany and Spain for the research progress meetings. The in depth study enabled the postulation of a new microorganism species (named “Comammox” (COMplete AMMonium OXidation). This research was very useful for the subsequent development of the control strategies to achieve full nitritation in biofilm reactors (Pérez et al., 2009), which were the key for developing the ANFIBIO technology just presented in the previous achievements.

Keywords describing research interests: wastewater treatment, biofilms, mathematical modeling, N-removal, bioreactors, automatic control.


  1. Pérez J, Lotti T, Kleerebezem R, Picioreanu C, van Loosdrecht MCM. 2014. Outcompeting nitrite-oxidizing bacteria in single-stage nitrogen removal in sewage treatment plants: a model-based study. Water Research, 66:208-218.
  2. Pijuan M, Torà JA, Rodríguez-Caballero A, César E, Carrera J, Pérez J. 2014. Effect of process parameters and operational mode on nitrous oxide emissions from a nitritation reactor treating reject wastewater. Water Research 49:23-33.
  3. Torà JA, Moliné E, Carrera J, Pérez J. 2013. Efficient and automated start-up of a pilot reactor for nitritation of reject water: From batch granulation to high rate continuous operation. Chemical Engineering Journal 226: 319-325.
  4. Jemaat Z, Bartrolí A, Isanta E, Carrera J, Pérez J, 2013. Closed-loop control of ammonium concentration in nitritation: Convenient for reactor operation but also for modeling. Bioresource Technology, 128:655-663.
  5. Bartrolí A, Carrera J, Pérez J. 2011. Bioaugmentation as a tool for improving the start-up and stability of a pilot-scale partial nitrification biofilm airlift reactor. Bioresour. Technol. 102, 4370-5.
  6. Bartrolí A, Pérez J, Carrera J. 2010. Applying ratio control in a continuous granular reactor to achieve full nitritation under stable operating conditions. Environ. Sci. Technol., 44, 8930-5.
  7. Pérez J, Costa E, Kreft JU. 2009. Conditions for Partial Nitrification in Biofilm Reactors and a Kinetic Explanation. Biotechnol. Bioeng., 103, 282-95.
  8. Costa E, Pérez J, Kreft JU. 2006. Why is metabolic labour divided in nitrification? Trends Microbiol., 14, 213-19.
  9. Pérez J, Picioreanu C, van Loosdrecht MCM. 2005. Modeling biofilm and floc diffusion processes based on analytical solution of reaction-diffusion equations. Water Res., 39, 1311-23.
  10. Gòdia F, Albiol J, Montesinos JL, Pérez J, Creus N, Cabello F, Mengual X, Montràs A, Lasseur Ch. 2002. MELISSA: a loop of interconnected bioreactors to develop life support in space. J. Biotechnol., 99, 319-30.


  1. Inventors: Isanta E, Carrera J, Pérez J A method and a system for wastewater nitrogen removal. Patent Application UK No.: 1317957.7. Patent Assignee: Univ. Autonoma de Barcelona (Spain). Date of registration 10 October 2013.
  2. Inventors: Isanta E, Carrera J, Pérez J, Campos JL, Mosquera A, Val del Rio A. A method and a system for enhancing Nitrogen removal in a granular sequencing batch reactor (GSBR) and a computer program product. Patent Application UK No.: 1313194.1. Patent Assignee: Univ. Autonoma de Barcelona (Spain) & Univ Santiago de Compostela (Spain). Date of registration 24 July 2013.
  3. Inventors: Baeza JA, Bartrolí A, Carrera J, Lafuente J, Pérez J. Nitrification of wastewater using biofilm reactor, uses closed control loop to regulate flow of wastewater entering reactor as function of ammonia concentration at reactor exit. Patent No.: ES2334321. Patent Assignee: Univ. Autonoma de Barcelona (Spain). Licensed to: AERIS Tecnologías Ambientales SL (since 1 January 2012).


Thesis: http://tdx.cat/handle/10803/5294


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