European centre of excellence
for sustainable water technology

Science & Technology Newsletter, September 2015

Published: 9 september 2015

                                    Guest Editorial by Dr. Elmar C. Fuchs, Wetsus Program Manager

Dear reader of the Wetsus S&T Newsletter, Fall Edition 2015,

Wetsus is blooming. The new building has gradually become a normality which is nevertheless admired and respected by many; its transparency can be seen as a corporeal token of our research attitude. With our highly sophisticated equipment and passionate, dedicated researchers, we are continuously striving for patentable technologies and discoveries worth publications in high-ranking journals, and last but not least to contribute to the improvement of the quality of living for mankind in a sustainable way.

As examples, the design of a process for supercritical water desalination with zero liquid discharge and the characterization of sulfate reduction in a hydrogen-fed bioreactor operated at haloalkaline conditions are presented in this newsletter. Moreover, we are proud to provide our readers with an interview with prof. Manuel Rodrigo, chairman of the working group Electrochemical Engineering of EFCE, under whose leadership the 7th European Summer School of Electrochemical Engineering was recently successfully held in the beautiful new environment that Wetsus has moved into, and which has thus become our new face, home and symbol.

Whereas outward features such as the looks of a building are landmarks of a healthy and sustainable organization, their inner meaning can be ambivalent, and one should always know what they truly represent. It is imperative that they are never mistaken as indications of a less desirable state, whose trademarks they can also resemble: a so-called “mediocracy”, which Wetsus certainly is not and never must be. In order to briefly elaborate, allow me to quote F. Tassano:

“…Mediocracy is not concerned with the quality or content of culture, but it does care to some extent about appearances. It is not interested in having genuine art, or real education, but it wants to be able to say “we have art” and “there is lots of education”. Its aim is to redefine existing activities to the point where it becomes impossible to complain that they no longer exist. … “

So a superficial glance, the impression of appearances, cannot determine whether the beautiful appearance of Wetsus is a mediocratic illusion or the outward reflection of its inner reality. However, we, as Wetsus staff, scientists, members and supporters, can easily ascertain that our emanations are genuine, that our appearance is not an illusion but a proper reflection of what we are and what we do: If we read further about mediocracy, we learn about its ethics:

“…The main distinguishing feature of the mediocratic ethic is dishonesty. Mediocracy stresses the importance of one thing while engendering its opposite. Some of the time this dishonesty is concealed. But, as in Orwell’s 1984, mediocracy’s ability to brandish contradictions is also part of its power. …”

foto elmar PC310469

Honesty and integrity are essential cores of the Wetsus values. So naturally, in our work, our human relations, they are and always will be a part of our daily routine, providing the basis for excellence on all levels.

It seems fit to conclude this editorial with Polonius’s last advice to his son Laertes, brought to us in the famous words of Shakespeare: “This above all: to thine own self be true. And it must follow, as the night the day, thou canst not then be false to any man.”

Dr. Elmar C. Fuchs


Wetsus Congress

Within less than one month the annual Wetsus Congress will take place again in De Harmonie in Leeuwarden. This key event for water technology in Europe will bring you new inspiration and contacts, and is not to missed!
Dates: September 28 and 29, 2015
Title: 'Talent hubs for innovation'
Link for program and registration:

Sold Out! An interview with Prof. Manuel Rodrigo on the 7th European Summer School on Electrochemical Engineering

For young electrochemical engineers just beginning their careers, there was no better place to be the week of June 22-26 this summer than at Wetsus, which hosted the 7th European Summer School on Electrochemical Engineering (ESSEE2015). This year, registration had to be closed four months in advance because the maximum number of 100 students was already reached—a testament to the excellent reputation of past Summer Schools, as well as the thorough planning carried out by the Wetsus PhD students and scientists who organized the event.

Manuel Rodrigo, Professor of Chemical Engineering at the University of Castilla La Mancha in Spain, is Chairman of the Working Party on Electrochemical Engineering of the European Federation of Chemical Engineering (EFCE). The Working Party sponsors the ESSEE, which has taken place once every three years since 1994. In this interview, he talks about how the event’s success stems from lectures by world-recognized professors, discussions on cutting-edge topics, and the excellent organization and inspiring atmosphere at Wetsus.

organising commitee Mauel Rodrigo
groepsfoto Manuel Rodrigo

Question: What is your role with the Summer School?

Manuel Rodrigo: As Chairman of the Working Party of Electrochemical Engineering of the EFCE, my role—always together with the secretary of the Working Party, Prof. Ann Cornell at the KTH Royal Institute of Technology, Stockholm—is to help and advise the local organizers about the best way to organize this event, based on the previous experience of the Working Party. To do this, Ann and I are assisted by all members of the Working Party, and their help is of an extreme importance. It is important to advise about the syllabus, potential lecturers, planning, and mistakes made in previous schools, and here the help of the members of the Working Party is always a guarantee of total success. Likewise, we also give support and promote interaction with the EFCE and with other members of the Working Party.

Q: How does the Summer School advance the mission of the Working Party on Electrochemical Engineering?

MR: The Summer School is one of the most important activities of the Working Party. It deals with the formation of the young electrochemical engineers, and it is considered as one of the most relevant academic events related to electrochemical engineering all around the world, with many other scientific organizations currently asking for information or trying to collaborate with the Working Party in order to organize similar events on other continents. From the Working Party, we aim to help our students acquire basic and advanced knowledge and skills of electrochemical engineering theory and practice from well-known and world-recognized professors and teachers. This provides the opportunity of communication between novel and experienced researchers and helps students to improve their networking.

Q: This year, the Summer School filled up in February with the maximum number of 100 participants. Is this unusual to fill up so early, and what is it about the program that makes it so popular among PhD students from around the world?

MR: During the last two decades, the Summer School has become a well-established event on an international scale. Even despite the crisis, the number of attendants has always been high. In this case, it has exceeded expectations, and reaching the capacity so early is both positive and negative. The positive side is related to quality. The Summer School has been more and more appreciated by students and their advisors, and this has to be related to the great effort made in the previous editions in order to get very high-quality academic events. The negative side has also a positive aspect: the electrochemical engineering community is growing, and because of that we have to be ready to give the opportunity to all potential students to attend the school. For sure, it will be difficult, but, at least, we have to try in the next Summer School.

Q: The Summer School was a five-day event in which the first four days focused on the most relevant aspects of electrochemical engineering, from fundamentals to applications, with lectures by highly recognized experts. The last day focused on innovative fundamentals of electrochemical engineering, with special attention to hot topics and emergent technologies. This year, what were some of the new hot topics that stood out to you?

MR: Yes, this is the way the school is typically organized. We aim to cover the most relevant topics in the first four days, and then we want to see what the hot topics in electrochemical engineering are, according to the view of the local organizers. You know that electrochemical engineering is an exciting area and there are many topics on the cutting edge. On occasion of ESSEE2015, I was greatly surprised by the great possibilities of capacitive deionization, both from the environmental and from the energy point of view. I hope this technology can be further developed and that in the next years we will see full-scale applications.

Q: What was your impression of how the event was organized by Wetsus?

MR: Wetsus really put together a great team of PhD students and staff members to organize the summerschool with help of members of the Working Party. Initially, I was surprised by the role of the PhD students of Wetsus, but after looking at the results I have to acknowledge their role and importance in the success of the school. I greatly appreciate their work!

Q: Have you worked with Wetsus scientists in some form previously, or is this the first time you have been to Wetsus? What is your overall impression of the science atmosphere and research facilities at Wetsus?

MR: I have heard of Wetsus and have followed their scientific production, but this was my first time at Wetsus. Impressive facilities and an outstanding team of researchers. Perfect organization. I’m greatly impressed at what I have seen. It is one of the top centers of water technology all around the world, and for sure we will hear about Wetsus in the next years. They have a very interesting view on the relationship between applied and fundamental research.

Q: As Professor of Chemical Engineering, your research has covered water-related areas such as the electrolysis of industrial wastewater and microbial fuel cells. Can you share a little bit more about your work in water-related areas?

MR: My research is now focused on electrochemical engineering, but some time ago it was centered on a completely different topic related to wastewater treatment: the biological nutrient removal processes. So, it could be said that I have been always motivated by water and wastewater treatment. Nowadays, we are very active in the integration of electrolysis with irradiation technologies for the removal of refractory pollutants and also for the disinfection of reclaimed wastewater, and we are also working for several companies in the application of electrochemical technology for the treatment of their industrial wastes. In a more fundamental research area, we are also working with microbial fuel cells—it is exciting to see how you can use microorganisms to produce electricity directly, although unfortunately we are far away from full-scale applications. We will see in the future.

Q: Finally, what are your general thoughts on the future directions of water science and technology related to electrochemical engineering?

MR: This is an exciting question. There are electrochemical technologies for water and wastewater that are already mature and with application at the full scale, such as electrodialysis, and others that are in the last stage of development and only need to be slightly improved, such as electrocoagulation and electrolysis for the treatment of industrial wastes, and others that are just in the beginning, like the microbial fuel cells. I think that in the next years we will see an increase in the number of applications with the use of electrolysis for disinfection and for the treatment of strongly refractory wastes and, for sure, very important novel applications of electrodialysis. Let’s see…

Article written by L.M. Zyga

logo WPEE interview Manuel Rodrigo

Supercritical seawater desalination produces drinking water with zero liquid waste

Most desalination methods for seawater or brackish water produce two streams: a desalinated water stream and a waste brine stream. The brine stream is either discharged into the ocean if the plant is located near the coast, which may have a negative impact on marine ecology, or else it requires extra treatment before disposal if the plant is located inland.

To overcome the problems associated with disposal of the brine stream, Samuel Odu, a PhD student at the University of Twente, working under Dr. Louis van der Ham and Prof. Sascha Kersten, along with Dr. Sybrand Metz at Wetsus, have investigated a new method of desalinating water with zero liquid discharge. The method, called “supercritical water desalination,” is a continuation of the research work started by Ingo Leusbrock at Wetsus.

Samuel Odu foto

“We are combining different aspects of chemical engineering (thermodynamics, phase separation, conceptual design, etc.) as well as theoretical and experimental work, to develop a process that eliminates the production of waste brine in seawater desalination,” Odu said.

In a recent paper published in Industrial & Engineering Chemistry Research, Odu and his coauthors explain how the process works. Supercritical water is defined as water at a pressure above 221 bar and temperature above 374 °C. The desalination process raises the pressure and temperature of salt water above the critical point, at which the salt water separates into a supercritical “vapour” phase and a liquid “brine” phase.

In its supercritical state, the properties of the water change drastically due to changes in hydrogen bonding. In particular, the solubility of salts in the supercritical phase decreases by several orders of magnitude. The solubility of the salt in the supercritical vapour is so low that its salt concentration meets the safe limit set for drinking water.

The supercritical desalinated vapour can be removed from the system, cooled into liquid water, and released to ambient conditions. This method results in a desalinated water yield of more than 93% for seawater, which is significantly higher than for other techniques, such as multistage flash distillation (about 50%) and reverse osmosis (35-50%).

The leftover liquid brine has a very high salt concentration (50 wt.% NaCl), and this highly concentrated brine can be “flashed”—a process of instantaneous pressure release. Flashing produces fine salt crystals in clusters that are easily removed, and it also produces steam at the release pressure.

While the process has many advantages, a major drawback is that it is energy-intensive. However, most of the energy put into the process can be recovered because the steam produced by flashing can be used for heat integration to reduce the overall energy consumption. Still, due to the high operational costs, the researchers predict that this method will work best as a post-treatment technique.

“We see this method being used as a post-treatment step to conventional desalination methods in regions where low-cost energy is available,” said van der Ham. “It may also be used to eliminate waste brine discharge into open waters, such as in the Middle East.”

The scientists have already demonstrated the supercritical water desalination method in a lab-scale unit for NaCl water streams. They have also designed a larger pilot plant (5 kg/hr feed) that is currently under construction at the high-pressure laboratory of the Sustainable Process Technology (SPT) research group at the University of Twente.

Samuel Odu artikel afbeelding conceptual design

“The plan is to complete the construction by the end of September, and start testing, then operation as soon as it is ready,” Odu said.

Samuel O. Odu, et al. “Design of a Process for Supercritical Water Desalination with Zero Liquid Discharge,” Ind. Eng. Chem. Res. 54 (2015) 5527–5535.

Article written by L.M. Zyga

Bacteria need a little help to remove sulfate under extreme conditions

One commonly used method to remove harmful sulfate from water is to use bacteria to reduce the sulfate into sulfide, which can later be converted to elemental sulfur and used in agriculture or the chemical industry. But so far, sulfate-reducing bacteria have never been thoroughly investigated under the extreme conditions of high pH and high salinity, such as those that occur in soda lakes.

For the first time, João Sousa, a PhD student at Wageningen University, working under Professor Alfons Stams, along with Assistant Professor Caroline Plugge and Wetsus scientist Martijn Bijmans, have investigated this sulfate removal method under extreme conditions. Their work is published in a recent issue of Water Research.

foto joao sousa

Using a bioreactor, the scientists found that the bacteria’s sulfate reduction activity decreases significantly under extreme conditions because the bacteria simply cannot aggregate inside the bioreactor. However, the results suggest ways to improve the biomass concentration, such as by adding silica particles for the bacteria to grow on.

bioreactor artikel joao
The scientists carried out their experiments inside a bioreactor inoculated with biomass, sediments, and sludge under carefully controlled haloalkaline conditions (pH 9, 1.5 M Na+). The bioreactor also received a supply of hydrogen gas because, under normal conditions, hydrogen gas and various organic compounds provide the electrons that the sulfate-reducing bacteria transfer to the sulfate.

Although the researchers continuously cultivated the biomass inside the bioreactor for more than three months, they found that the extreme conditions severely hindered the biomass growth rate and resulted in a complete absence of aggregation. The researchers aren’t exactly sure why the biomass did not aggregate, but possible explanations may include reduced metabolic activity under extreme conditions and low microbial diversity.

Of the small amount of sulfate reduction activity that did occur, the majority was performed by the biofilm on the bioreactor’s glass wall, not by the biomass suspended in the water. This observation suggests that glass, a silica-based material, may provide attachment support for aggregation, and raises the possibility that adding other silica-based materials such as sand and pumice could lead to increased aggregation in the water. In the future, the researchers plan to pursue this idea to further investigate the underlying mechanisms of the aggregation process in extreme conditions.

J.A.B. Sousa, C.M. Plugge, A.J.M. Stams, and M.F.M. Bijmans, “Sulfate reduction in a hydrogen fed bioreactor operated at haloalkaline conditions,” Water Research 68 (2015) 67-76.

Article written by L.M. Zyga
Color SEM picture artikel Joao

Professor aims for clean water in Saudi Arabia and beyond

Hans Vrouwenvelder, Professor in the Department of Biotechnology at TU Delft, has been researching the production and distribution of clean water in the Netherlands (including at Wetsus) for many years. In 2009, he decided to move to Saudi Arabia to work as a visiting professor at the King Abdullah University of Science and Technology (KAUST) in the Water Desalination and Reuse Center (WDRC). During the past six years, he has tackled clean water challenges in the Middle East, combined insight into water technology from different regions of the world, and nurtured the talent of young researchers as they begin their careers in the field of water research and technology.

“The campus located at the Red Sea is beautiful, has all facilities nearby, and is very well organized,” said Vrouwenvelder, who is currently working at KAUST. “Visiting the KAUST website will give a good impression. The research is very stimulating because of the excellent students, faculty and research possibilities. Different from The Netherlands may be the stronger community atmosphere at KAUST. You get to know the people better and there is more time to interact. I experienced that the Saudi people are very open, friendly and helpful. My experience in the Middle East confirmed to me that relationships, trust and being passionate about research are key for excellent research.”

Hans Vrouwenvelder Photo 12 July 2013

In one example of this research, Vrouwenvelder and coauthors from TU Delft, KAUST, and the Swiss Federal Institute of Aquatic Science and Technology have published a paper in Water Research in which they report some surprising results suggesting that the concept of “biological stability”—upon which drinking water guidelines are based—needs to be revised.

In that study, the researchers for the first time applied a combination of advanced sensitive microbial techniques to examine how the bacterial community in drinking water changes over short time periods of minutes, hours, and days. The results showed that, although the bacterial community does not change very much over short time periods, it does become more diverse and rich as the water flows from the outlet of a treatment plant to a faucet. Using modern techniques such as pyrosequencing and flow cytometry, the scientists determined that an increase in rare bacterial taxa, which does not have negative hygienic implications, is responsible for the majority of this change.

While water guidelines state that a stable bacterial community is desirable in drinking water, the results here show that water distribution systems are inherently dynamic and unstable, yet still safe. Consequently, biostability is not an absolute measure of safety. In light of these results, the researchers believe that the concept of biological stability needs to be revised and quantified to allow a certain degree of change in the microbiology of drinking water. Ultimately, a better understanding of the biology of drinking water may lead to a reduction in the energy, chemicals, and cost of water treatment.

Improvements like this would not be possible without dedicated, motivated people behind them, which is why Vrouwenvelder places a high priority on encouraging his colleagues, especially students.

“In my opinion, it is most important to increase the confidence of students in their capabilities and possibilities,” he said. “The acknowledgement sections of MSc reports and PhD theses often mention the appreciation for stimulation, enthusiasm, constant support and unlimited trust, feeling of both freedom and safety, and caring about the students’ well-being.

“Two French undergraduate students, Laurie Fel and Marion Fresquet, just completed a three-month internship with me and Emmanuelle Prest [researcher at TU Delft]. We had nice discussions about the research, and they did excellent research. Both Laurie and Marion travelled by plane to Germany for a meeting in which they presented the study results. For me it is nice to see that they were open to doing a presentation in English for a group of experts. And their presentation was excellent. Laurie and Marion will co-author a publication based on their work. Several students mentioned that during their MSc study, they changed their mind about research and pursued a PhD study. Interaction with and stimulation of students is just as, or even more, exciting and relevant as the research.”

Along with collaborating with students, Vrouwenvelder is also collaborating with companies in Saudi Arabia to bridge the gap between science and application. All of the scientific research that begins in the lab will ultimately contribute to the ambitious goal to provide clean, low-cost water worldwide.

“Goal 5 of the United Nations 2030 agenda for sustainable development aims to ensure availability and sustainable management of water and sanitation for all, involving access to safe and affordable drinking water for all, pollution reduction, and increasing recycling and safe reuse globally,” he said. “The focus of research of my group is on microbiological and technological aspects of water sources, treatment and transport. For water treatment, in situ non-destructive techniques to image fouling processes such as optodes and optical coherence tomography can be of relevance for practice and exciting for research. For biological stability, I would like to study biofilm and water interactions in distribution networks and premise plumbing, including which bacteria are active and what they are doing.”

Joline El-Chakhtoura, et al. “Dynamics of bacterial communities before and after distribution in a full-scale drinking water network,” Water Research 74 (2015) 180-190.

Article written by L.M. Zyga

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