Onno Kramer is awarded a PhD on 'Hydraulic modelling of liquid-solid fluidisation in drinking water treatment processes'
On Friday September 10, Onno Kramer obtained his doctorate with the subject 'Hydraulic modelling of liquid-solid fluidisation in drinking water treatment processes'. This research, one of his opponents called very weighty (as much as 1.2 kilograms), is about an important part in the chain of water treatment, which he is involved with in his work at Waternet.
The importance of good water purification is evident from the fact that 'only' 0.01% of all the water in the world is usable, while 8 billion people should be able to use it. The fact that we can tap clean and reliable water is thanks to a long series of purification processes through which the water passes. Purification is subject to increasingly strict requirements and it is extremely important that this takes place in an increasingly sustainable manner.
Onno Kramer's subject is the softening of drinking water, which is done by passing the water along grains (calcite pellets) in large cylindrical fluidised bed reactors and co-feeding a strong base. With just the right amount of fluidisation, this leads to favourable conditions in which the calcium from the water efficiently crystallises to lime sticking on the grains. While in the past these grains were ‘thrown away’, reuse is increasingly the order of the day. By modifying the process, we can now reuse the residue as a raw material in the softening process.
Moreover, to cope with future (un)expected circumstances, current full-scale water treatment plants should adapt and improve their design from robust to more flexible. Therefore reliable and effective process models are required. In these models the particle diameter of grains is an important input variable. In most models, also in the case of non-spherical particles such as calcite pellets, the spherical diameter is used. This leads to the question: "What is the diameter of a banana?" A rather important question, it appears from the lecture Kramer gave prior to his PhD.
Kramer's promotion is a fine example of a DPTI collaboration between the faculties of Civil Engineering & Geosciences (CiTG) and Mechanical, Maritime and Materials Engineering (3ME).
