INTERN - Process – Optimalisation contactor design

Location: Andijk / Amsterdam

Company profile

PWNT is unique in its formation and mission to make the utility’s more than 98 years of experience and innovations in water treatment available worldwide. Our extensive R&D programmes have led to the development of efficient and sustainable solutions in water treatment based on suspended ion exchange, ceramic membrane applications and advanced oxidation, and these applications can be used for a wide variety of water sources.

All of our solutions offer lower life cycle costs, greater efficiency and a much lower environmental impact. We work closely with our clients to create optimal results and strongly believe in partnering with universities and globally-respected companies. PWNT is located in the Netherlands and Singapore.


PWNT is looking for a student with a background in process or mechanical engineering. Does flow distribution (CFD modelling) have your interest and do you want to make a model and have the opportunity to test it on large scale? Then this internship, where you work from Andijk, the Netherlands, might be interesting for you!

Your assignment

One of our main processes is the SIX® process. Resin is added to the incoming water and passed through five contactors connected in series. An air system ensures that the resin does not settle and that the contact surface around the resin is constantly refreshed to guarantee a good ion transfer. After these contactors, the resin is separated from the water again. The water goes to the next process and the resin is regenerated and can then be used again.

Currently, the contactors are alternately flowed from above and below but because the water resin is mixed thoroughly, it is suspected that this is no longer necessary.

To investigate this, we have a large test installation of 30 m3/h available in our development center. The assignment consists of the following parts:

  • Create a (simple) CFD model of the contactors;
  • Test the behavior of the current set-up at different water and air flow rates by means of residence time distribution;
  • Evaluate the model based on practical measurements;
  • Repeat tests, after conversion;
  • Based on the residence time distribution and the known ion exchange rate over time, an overall effect of the adjustment can be assessed.

Depending on the time available, the influence of the number of reactors, or any other ideas that arise on the basis of the tests described above, could also be considered.

Your profile

To be the perfect match for this internship, you:

  • are a student with a background in Process or Mechanical Engineering;
  • are able to make a small CFD model to predict the behavior of the system;
  • are proactive and creative;
  • are able to report in English.

This internship lasts at least 4 months. As a minimum you are working at least 2 days per week in Andijk (probably more while in the phase of performing practical tests). The other days you are flexible to work from home or from our head office in Amsterdam.

We expect a lot from you, but you can also expect a lot from us. What do we offer you?

  • Internship compensation according to applicable law and regulations;
  • A great international working environment;
  • Compensation for travels;
  • Possibility to stay overnight in Andijk for some days per week to avoid travelling.


Would you like more information about our organization? Please check out our website:

If you are interested and would like more information about this internship, please contact Marcel Welling:

To apply, please send a motivation letter and a CV to

We look forward to your application!

Acquisition in response to this vacancy is not appreciated.