Wednesday 18 November turned out to be a landmark day for the
Membrane Technology research group when a PhD was conferred on two
of its members at the Fries Museum in Leeuwarden.
The conferral of a PhD is always an academic high point for a
research group, all the more so when you get two at once and the
ceremony is held outside the university. That is exactly what
happened at the Membrane Technology research group on 18 November.
The Executive Board had agreed to make a one-off exception and
allow the degrees to be conferred in a museum. Piotr Długołęcki and
Perry van der Marel were awarded their PhDs on Wednesday 18
November in the Fries Museum in Leeuwarden.
Wetsus
Both Długołęcki and Van der Marel had expressed a wish to
receive their PhD in Leeuwarden, primarily because they had carried
out their research locally at Wetsus, a leading institute in
sustainable water technology that works closely with universities,
including UT, and businesses. Wetsus' mission is to combine
excellent scientific research with practical applications and
commercial relevance.
Długołęcki and Van der Marel both carried out their research
there. Długołęcki, who was investigating blue energy, was
supervised by Professor Matthias Wessling and Dr Kitty Nijmeijer.
Van der Marel, who was working on membrane bio-reactors, was
supervised by Professor Walter van der Meer and Dr Antoine
Kemperman.
Blue Energy
Blue energy - Długołęcki's field - is a relatively new, but
highly promising source of sustainable energy. It is generated at
places where salt and fresh water come together, usually where
rivers flow into the sea.
When salt dissolves in water, it releases ions. So, salt water
contains many more ions than fresh water. This difference lies at
the heart of 'reverse electrodialysis', the process for generating
blue energy, whereby positive or negative ions are selectively
filtered by special membranes. The difference in voltage across the
membranes is then converted into electricity. Długołęcki improved
this method (the most researched method in the Netherlands for
generating blue energy), thus raising the output of blue
energy.
To generate the maximum volume of energy, the water needs to be
well mixed and to flow evenly across the membranes. This is
achieved by placing a mesh-like structure - called a spacer -
between the membranes. The problem with spacers is, however, that
they cannot transport ions. Długołęcki has now solved this problem
by developing a conductive spacer, which can double or even treble
the energy output.
Membrane bioreactors
Van der Marel specializes in membrane bioreactors (MBRs). An MBR
is a water treatment installation which separates activated sludge
from purified water by applying membrane filtration. Activated
sludge is a mix of bacteria that purify the water. Membrane
technology is preferable to conventional water treatment systems
because it takes place on a smaller surface (decantation tanks are
no longer needed) and it delivers higher levels of purification.
The main pitfall is that it costs more and more energy to transport
water through membranes which have become contaminated by deposits
left on the surface or in the pores by components in the sludge.
Hence, to make a membrane bioreactor more productive, the levels of
contamination needed to be lowered. Van der Marel worked out the
optimal membrane characteristics, thereby reducing contamination to
a minimum. This, in turn, lowers costs and raises output at the
same time.
Exciting day
With a turnout of 140 - colleagues, friends and family - the
'Window' Hall in the Fries Museum was filled to capacity.
As Chair of the Doctoral Committee, Professor Gerard van der
Steenhoven extended a warm welcome to the visitors. He pointed out
that this was a unique situation for the Faculty of Science and
Technology and for the University of Twente as a whole. Van der
Steenhoven was glad to see such a high turnout, not least because
he wants to see the public take a more active interest in science
and technology.
Both PhD candidates felt nervous. Długołęcki: "I was pretty
anxious beforehand, but now that it is all over, I'm glad
everything went well." Van der Marel also admitted to feeling 'a
bit apprehensive' at first. Afterwards, he was wildly enthusiastic:
"I'd advise everyone to do it this way!"
