Ir. Onno Kramer

My name is Onno Kramer (1967). After obtaining my B.Sc. and M.Sc. degrees in Chemical Engineering at Twente University in the Netherlands, I travelled across Australia and Europe (especially Spain), worked as a freelance IT expert in the financial service sector and joined Amsterdam’s drinking water company Waternet. As an engineer and Senior Advisor, I work on water quality and process technology. In my job, the focus is lies on improving process performance and optimisation, sustainability and on-site innovations. I absolutely love my work, I am inquisitive by nature and I always want to know how things work. This is why I love to collaborate with students: they have an open-minded attitude and great enthusiasm for new and innovative water-related ideas, which I then try to translate into inspiring projects.

Under my supervision, more than 65 students have so far successfully completed their interim internship, multi-disciplinary project or graduation assignment at Waternet. Through these joint ventures, I myself am constantly learning and improving, too. Each student is unique, but all of them make tremendous contributions to our research projects and develop the necessary experience and skills. In addition to addressing theoretical and fundamental questions, we also explore many practical research challenges. In other words: we have more than enough projects for interested students. Finally, on behalf of the Applied University of Utrecht and Hobeon/NQA, I am a member of several committees: the “Supervisory Committee”, the “Professional Fields Advisory Board” and “Nationwide B.Sc. Educational Assessments”.

In November 2016, I embarked on a PhD project as a research assistant or ’contract promovendus’. I study the hydraulic modelling of liquid-solid fluidisation in drinking water treatment processes and develop models to address sustainability goals, practical implementation challenges and optimisation aims. The models acquired are then calibrated in an experimental set-up of a pilot plant and subsequently validated in a full-scale installation.

In the Netherlands, an annual 400 million m³ water is softened in drinking water treatment plants applying fluidised bed pellet reactors. In these reactors, sand is generally used as seeding material and marble pellets are produced as a by-product. To improve sustainability, calcite pellets are dried, grained and sieved and re-used as seeding material.  To predict the fluidisation behaviour of particles in fluidised bed reactors, theoretical knowledge is generally used that pertains to spheres that are perfectly round rather than irregularly shaped. For such natural (irregular) particles, numerous semi-empirical models have been published, but there is no general agreement on which equation is the most accurate.

My research aim is to obtain substantially more detailed knowledge on the hydraulics of liquid-solid fluidisation phenomena to optimise the softening process in fluid bed reactors. Research will take place at the Weesperkarspel facility of Waternet in Amsterdam and in the Science Lab at HU University of Applied Sciences Utrecht, Institute for Life Science and Chemistry, Department of Chemical Engineering.

Onno is affiliated with Queen Mary University of London, School of Engineering and Materials Science where he is an honourable member of the Division of Chemical Engineering.
Grant for Erasmus+ staff mobility for teaching and training at QMUL 2019.

A number of our students have been awarded prizes in the annual graduation report contest:
2018 HU-ILC students (Timo van Bergen, Herman Klok, Stan Turk & Michel Vrieswijk) rewarded for the ‘’Parel’ i.e. projects with impact. Presented at the opening of the academic year (SDA movie)
2018 Awad Elarbab nominated for the KNW contest
2016 Liselotte van den Hout: 2nd prize KNW
2015 Mohamed el Mokaddam: 2nd prize KNCV
2014 Mark Jobse: 1st prize KNW
2014 Marc Schetters: 2nd prize KNW
1991 Onno Kramer (me): 4th prize Dutch Royal Engineering Society

And there is more
In my spare time, I compose flamenco music and choreographies, which I perform with other musicians and dancers in small theatres. I was a member of student rowing clubs for many years. In 1989, I won my first rowing medal, "blik", with a fantastic team called “Zwaar’88” that is still going strong today. In 1994, I won my first “Heineken Roeivierkamp” medal as a stroke and had the opportunity to row on the river Thames in the “Head of the River Race” contest in London. I live together with Karin in the small and beautiful town of Weesp in the vicinity of Amsterdam.


  • O.J.I. Kramer, J.T. Padding, W.H. van Vugt, P.J. de Moel, E.T. Baars, E.S. Boek, J.P. van der Hoek, Improvement of voidage prediction in liquid-solid fluidized beds by inclusion of the Froude number in effective drag relations, International Journal of Multiphase Flow. 127, 103261 (2020) 1–13.
  • O.J.I. Kramer, P.J. de Moel, J.T. Padding, E.T. Baars, Y.M.F. el Hasadi, E.S. Boek, J.P. van der Hoek, Accurate voidage prediction in fluidisation systems for full-scale drinking water pellet softening reactors using data driven models, Journal of Water Process Engineering. 37, 101481 (2020) 1–15.
  • O.J.I. Kramer, P.J. de Moel, E.T. Baars, W.H. van Vugt, J.T. Padding, J.P. van der Hoek, Improvement of the Richardson-Zaki liquid-solid fluidisation model on the basis of hydraulics, Powder Technology. 343 (2019) 465–478.

Onno Kramer

  • Faculty of Civil Engineering and Geosciences

    Building 23

    Stevinweg 1

    2628 CN Delft

    Room: 4.54