Researcher at the University of Twente improves water treatment
Optimum membranes reduce costs and raise water yields
20 November 2009
Membrane bioreactors (MBRs) are waste water treatment plants in which the separation of active sludge and purified water takes place by means of membrane filtration. A big problem with MBRs is that the membranes in question become fouled. Perry van der Marel of the University of Twente and Wetsus have developed a measuring method and used it to improve MBRs. This will reduce the costs of operating MBRs and raise water yields. Van der Marel obtained his doctorate at the University of Twente’s faculty of Science and Technology on 18 November 2009.
Membrane bioreactors (MBRs) are waste water treatment plants in
which the separation of active sludge and treated water takes place
by means of membrane filtration. Active sludge is a mixture of
various sorts of bacteria that purify the water. The most important
advantages of using membrane technology over using conventional
waste water treatment plants are that less ground is required as
settling tanks are no longer necessary, and that the treated water
is of a better quality. A big problem with membrane bioreactors is
that the membranes in question become fouled by the sludge. This
fouling occurs because sludge deposits on the membrane surface or
in the pores of the membrane. It therefore takes gradually more
energy to get the water through the membranes. The fouling has to
be reduced if the use of membrane bioreactors is to become more
remunerative. Perry van der Marel of the University of Twente and
research institute Wetsus have optimized membrane properties in
such a way as to minimize fouling. As a result, the costs go down
and more water can be produced.
Membrane properties
The membranes used in MBRs have various pore sizes and
shapes, and are made from different materials. Van der Marel has
developed a new measuring method - the Improved flux step
method - which can be used for all types of membranes and
sludges. This method determines the effect of different membrane
properties on the maximum water flux that can be achieved through
the membrane concerned. Van der Marel investigated 15 commonly-used
and self-made membranes and concluded that hydrophilic membranes
with large pores and high porosity work the best. Selecting the
optimum membrane properties can lower the costs involved in using
MBRs since there is less fouling which, in turn, enables a higher
flow. This results in twice the water yield. Furthermore, it
obviates or reduces the need for chemicals to clean the
membranes.
Mobile membrane bioreactor
Van der Marel has also built a mobile membrane bioreactor,
which, if placed next to a large plant, can rapidly measure whether
the best possible membranes and conditions have been selected for
the latter.
Note for the press:
Perry van der Marel obtained his doctorate at the
University of Twente's faculty of Science and Technology on 18
November 2009. He carried out his research within the department of
Membrane Technology and the research institute IMPACT. His
supervisors were Prof. Walter van der Meer and Dr Antoine
Kemperman. The summary of his PhD thesis, 'Influence of membrane
properties on fouling in MBRs' is available in digital form on
request.
Press Contact: Rianne
Wanders, +31 (0)53-4892721.
