Promovendi (m/v)
Het onderzoeksprogramma van Wetsus is verdeeld in diverse thema's. Binnen deze thema's zijn specifieke researchonderwerpen gedefinieerd, welke als promotieonderzoeken worden uitgevoerd.
Voor de invulling van het onderzoeksprogramma zijn wij op zoek naar promovendi (m/v) voor onze researchprojecten:
Clean water technology
1: New reactor concepts for chemical degradation of trace organic compounds and
disinfection.
Disinfection and removal of trace organic compounds is of utmost importance for the production of safe drinking water. Often, these aspects are combined in one treatment process like ozonisation or UV-oxidation. In this project, the hydrodynamic aspects of UV reactor systems will be explored. Detailed mathematical models will be developed that describe flow fields, residence time distributions, UV dose, mixing, degradation and inactivation kinetics. The knowledge coming from these models will be applied to develop new and innovative UV reactor concepts that utilize the advantages of hydrodynamic optimization and will reduce energy consumption significantly. The project will develop and test a prototype of this new generation UV reactor.
The project is carried out at Technical University Delft
2: Advanced oxidation with a new ozone plug flow reactor in combination with UV
treatment.
In this project a new advanced oxidation technology (DOPFR-UV), based on a new UV
reactor developed in a parallel running TTI-W project and a Dissolved Ozone Plug Flow
Reactor (DOPFR) will be developed. In this concept a double barrier for pathogens and
organic micro pollutants exists. The combined systems offer a large flexibility as a water
treatment system. Fine tuning of the ozone and UV dose will provide opportunities to fine
tune the system to the required disinfection and organic contaminant control.
Furthermore, no excess hydrogen peroxide has to be removed after treatment.
The project is carried out at Technical University Delft
3: Air/water cleaning to control membrane fouling
Background
High-pressure membrane processes, i.e. reverse osmosis (RO) and nanofiltration (NF),
are increasingly used in drinking water treatment, seawater desalination, waste water
reclamation and for the production of water for industrial uses. The potential for the
removal of salts, pathogens, pesticides, hormones, pharmaceuticals and other possible
threatening priority compounds from feed waters by NF/RO make these membrane
processes highly attractive in a world with shortage of clean and fresh water. The largest
problem in using membrane processes, however, is the occurrence of membrane fouling
resulting in performance loss and operational problems resulting in an increase of the
total treatment cost which limits the use of NF/RO. The new and innovative AiRO process
uses air/water cleaning of vertically positioned membrane elements to control membrane
fouling.
Research questions
To effectively apply AiRO in practice, an alternative NF/RO design is necessary using
vertically positioned membrane elements, completely different from conventional NF/RO
design applied worldwide. The most efficient use of the AiRO technology depends on the
optimal use of air/water cleaning in membrane elements. Although initial research
showed the effectiveness of the process, many fundamental questions still remain
unanswered. Some of these questions involve:
the mechanical/physical understanding of air/water cleaning of membrane elements,
the effectiveness of the air/water cleaning process in relation to different feed
components, the long term behaviour of air/water cleaning.
The first two research questions will be investigated using CFD modelling parallel to
laboratory tests and will be the heart of the PhD project. Long term air/water cleaning
behaviour will be investigated in on-site pilot-scale research in a parallel research project.
Research project
The research will be carried out by a PhD student and is supervised by prof. Walter van
der Meer of the University of Twente (Enschede) and dr. Emile Cornelissen of Kiwa
Water Research (Nieuwegein). Furthermore, we participate in this project with other
research institutes (Wetsus) , system suppliers (Hatenboer) and all the Dutch drinking
water companies (e.g. Vitens, Waternet, Evides, PWN,…).
The project is carried out at KIWA Water Research Nieuwegein
Distribution
4: Characterization of plastic pipes by accoustic measurements
No specific information available yet.
Research theme ideas: Producing, and especially distributing, drinking-water is a great
job because it’s such an important product for us all.” Jenne van der Velde, theme
manager for Water Distribution, and Asset Manager at Vitens, discusses his theme.
The network of drinking-water Pipelines in the Netherlands is very extensive. It varies in
age between being laid today and a century ago, and many different materials and laying
methods have been used. The replacement value of the whole network is more than €10
billion. The condition of the network is hard to gauge, mainly because it is all
underground and we are not always completely sure where. One specific section of the
network could be leaking while another section, a metre further up, could be in perfect
condition.
New technologies are vital, especially for keeping an eye out for future developments
while choosing whether to repair or replace a pipeline. Within the BTO, research has
been going on for years into the various facets of water distribution; design, breakdown
mechanisms and modelling. This research will deliver new inspection techniques,
allowing the condition of pipelines and appendages to be determined at low cost.
Developments such as (ultrasonic) sound, magnetic wave and radar technologies are
very relevant today. Fundamental research is necessary to correlate the condition of a
pipeline to specific, measurable parameters and to the breakdown mechanism.
The ambition for this theme is to work together towards an ultimate goal – the in-line and
on-line inspection of pipelines for €500 per kilometre, and the ability to make wellfounded
decisions about the possible replacement of pipelines.
5: Localization and integrity of pipes in the underground
See project 4.
Desalination
6: Surfactant-based reversible salt concentration.
In this project mixtures of polyanions and polycations will be used to concentrate saltcontaining streams from “low” salt concentrations of below 5% up to concentrations of
above 20%, thus avoiding the common water evaporation step. The principle for this is
based on the tunable binding properties of polyanions and polycations: by changing
temperature and/or presuure, it is expected that binding can be changed from Na+ to the
polyanion and Cl- to the polycation towards a mutual binding between the two polyions as
a result of increased apolarity of the polyions and stronger electrostatic interactions. As a
result, NaCl will be expelled, which is expected to happen at high NaCl concentrations.
An ultrafiltration step will be used to retain the polyions together with the bound NaCl and
to provide a desalted water stream.
Biofouling
7: Control of biofilms on membranes used in drinking water production.
Starting from November 2008 we are looking for new PhD students in the area of control
of biofouling and biofilm research.
Waste water technology
Algae
8: new projects to be defined in upcoming months
Organic waste streams
9: Hydrolysis of concentrated fermentation waste streams. 1 year Post-doc
Biological or chemical and/or physical treatment methods to degrade fermentation waste
streams (cells of fungi, yeast and bacteria) into easily degradable components to produce
biogas. Possible continuation as a PhD
Advanced waste water technology
10: Algae reactors integrated in waste water treatment
No specific information available yet. But may include fluidized bed reactors in which the
microreactors contain a normal light source instead of UV.
Membrane bioreactors
11: Robustness of MBR treatment of industrial wastewater under varying conditions*
Compared to conventional activated sludge treatment, membrane bioreactors (MBR)
offer several (potential) advantages including a smaller foot-print and, because it is free
from solids, the possibility to re-use the effluent as process water. A major question
however is the robustness of the system under conditions of shock-loads of pollutants
such as organic compounds and ammonium (in case of a nitrifying MBR) and strong
fluctuation in environmental conditions such as temperature and salt concentration. The
questions that need to be addressed are (1) how does the MBR system respond to
changes in the aforementioned parameters with respect to biological performance and
membrane fouling, (2) what are the underlying mechanisms (flocculation, conversion
rates, recovery rates, etc.) and (3) what are possible solutions to counteract these
disturbances.
* Final approval of this project is in progress, and is expected by 15 July 2008
12:Treatment of nanofiltration concentrates
Nanofiltration (NF) of the effluent of municipal wastewater treatment plants (WWTPs) is a
promising technique as it results in a permeate that can be used as a source for
(industrial) process water, irrigation water or even for the production of drinking water. A
major bottleneck is the NF concentrate that somehow needs to be disposed of, which
accounts for the majority of the costs. However, NF concentrates also presents some
interesting opportunities because several compounds are present at enhanced
concentrations such as phosphorus, heavy metals, multivalent cations and organic
micropollutants. This may allow (1) then recovery of phosphorus for direct reuse as a
fertilizer, or for the production of higher grade phosphorus products, (2) easier removal of
the concentrated heavy metals, (3) recirculation of multivalent cations to the biological
reactor stimulating flocculation of the sludge and (4) an improved and/or easier removal
of the organic micropollutants. Research aspects that need to be addressed include the
development of an innovative WWTP flow scheme based on NF polishing and NF
concentrate treatment, technology selection for removal of heavy metals and organic
micropollutants, and the effect of NF concentrate recirculation on the primary functions of the WWTP, i.e. flocculation, COD removal and nitrogen removal.
13: Use on-line measurement of sludge filterability to control membrane operation in municipal MBRs**
In a previous study at Wetsus an improved flux-step method was developed to assess
the effects of membrane properties on membrane fouling in MBR systems for the
treatment of municipal wastewater. When applied on-line, this method can also be used
to determine the optimum flux at which membranes are operated. In this manner energy
can be saved which otherwise would be consumed to clean the membrane surface. This
optimum flux not only depends on the properties of the membranes that are used, but in
particular on the properties of the feed sludge. These properties vary in time caused by
changes in wastewater quantity, wastewater composition and environmental conditions.
The research questions that need to be addresses are (1) what are typical variations in
sludge filterability, to be determined with the flux-step method, (2) how should membrane
operation respond to this with a suitable control strategy and (3) are other (automated)
options available to counteract (temporary) decreases in sludge filterability, f.e. the
addition of additives such as powdered activated carbon.
** Final approval of this project is in progress, and is expected by 15 July 2008
Energy
14: Follow up Reverse Electro Dialysis (=Blue Energy). >January 2009
Reverse Electro Dialysis (RED) is a non-polluting technology to generate energy from the
mixing of fresh and salt water. Advantages are endless availability of fuel and no SO2,
CO2 and NOx exhaust.
In RED, a concentrated salt solution and fresh water phase are brought into contact
through an alternating series of anion exchange membranes (AEM) and cation exchange
membranes (CEM). Due to concentration difference between both solutions, anions
migrate through the AEM towards the anode and cation move through the CEM towards
the cathode, thus generating a potential difference. Electricity is generated from this
potential differfence at the electrodes.
Sensoring Monitoring en Control
Safety and Environment
15: Raman spectroscopic sensing of bacteria in water using photonic crystal cavities
The goal of this project is to study and establish the physical mechanisms for sensing of
bacteria in water based on a nanocavity in a two-dimensional photonic crystal (PhC).
Such a crystal is a periodic modulation of the dielectric constant, with a modulation period
comparable to the wavelength of light. The nanocavity is an ultra-small resonator for
electromagnetic waves inside the crystal, leading to a greatly enhanced and locally
concentrated optical field. This property can be applied for both optical trapping of
bacteria in water and their subsequent identification by Raman spectroscopy. These
functionalities of PhC cavities will lead to rapid on-line sensing and identification of
bacteria in water. One candidate will concentrate on Raman spectroscopy and
cooperating with PhD student working on trapping bacteria in the phtonioc crystal
cavities. We look for experimental physicists (M.Sc.) with a background in photonics or
solid-state physics and with affinity to bio-sensing. Experience in device fabrication is
helpful. The project is carried out at the Technical university Delft
Process monitoring and control
16: Projects in second half 2008.
Interaction Natural Systems
New water sources
17: Algorithms for hydrogeological parameter estimation from sensor data of
interaction with natural systems
Analysis of groundwater head fluctuations caused by natural stresses using timeseries
measurements. The interactions with natural systems constantly stress aquifers
everywhere for free, including the effects of rainfall, evaporation, river stages, and
groundwater pumping. Some of these stresses are the result of natural processes such
as the hydrological cycle. Others are the result of human activities, such as groundwater
pumping and canal stage fluctuations of managed systems. These stresses will all be
grouped under the term natural stresses. Novel and powerful algorithms for the
determination of hydrogeological parameters from time series measurements of observed
groundwater heads and natural stresses will be developped. Application of the algorithms
will constitute an accurate, comprehensive, efficient, and independent approach to obtain
values for hydrogeological parameters at a large number of locations in the system.
The project is carried out at Kiwa Water Research in Nieuwegein.
Het profiel
Behoor je tot de beste onderzoekers van je jaar, ben je enthousiast over multidisciplinaire samenwerking en ben je universitair afgestudeerd in richtingen als milieutechnologie, chemische technologie, membraantechnologie, electrochemie, microbiologie of verwante richtingen dan ben je de ideale kandidaat voor ons.
Kandidaten die in de loop van 2007 afstuderen worden eveneens uitgenodigd om te solliciteren.
Het aanbod
Je krijgt de kans mee te groeien met een innovatief, dynamisch en toekomstgericht toponderzoeksinstituut. Je kunt een stempel drukken op de ontwikkeling van nieuwe watertechnologie in samenwerking met vooraanstaande bedrijven en universiteiten. De standplaats is Leeuwarden. Het salaris is conform de CAO van de VSNU voor promovendi. De promovendi die wij zoeken worden door de in Wetsus participerende universiteiten in dienst genomen.
Informatie en Sollicitatie
Je kunt je schriftelijke sollicitatie, voorzien van c.v., sturen naar Wetsus, t.a.v. de afdeling Recruitment, Postbus 1113, 8900 CC Leeuwarden of per email recruitment@wetsus.nl.
Voor meer informatie over ons aanbod en de gestelde eisen kunt u contact opnemen met Dr. G.J.W. Euverink, 058-2846200, gertjan.euverink@wetsus.nl.
