European centre of excellence
for sustainable water technology

Science & Technology newsletter, April 2015

Published: 9 april 2015

                                       Guest Editorial by Bert Hamelers, Program Director Wetsus

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

Wetsus has moved into her new building and everybody is energized by the new work environment. The technological hall, the laboratories, and the workshops are spacious and well equipped, and are an inspiring place to perform even more top-level research.

Good facilities are a prerequisite for good science, but the facilities are purely a necessary tool. The crucial element of the success of Wetsus is the group of people performing science. At the heart of this group are the PhD researchers, young people who have taken the bold choice to pursue science as the start of their career. It is their dedication and creativity that pushes our research forward.

Coaching and training is an important element of the PhD researchers success. Therefore we are very happy that Wetsus was awarded the opportunity to organize the 7th European SummerSchool on Electrochemical Engineering, an advanced-level summer school for PhD students and young industry professionals. The organization of the summer school lies in the dedicated hands of a hardworking team of Wetsus PhD students, supported by the working group of the European Federation of Chemical Engineers (EFCE). The summer school will be held in June, but the application process had to be closed already in February because the maximum number of 100 attendants was already reached. I wish the very best to the PhD group organizing this event.

Electrochemistry in a broad sense is of great importance for many fields of interest for Wetsus. This scientific field is actively explored by Wetsus as a basis for innovative water technology, for example for topics such as capacitive deionization, blue energy, and microbial fuel cells (MFCs).

It is therefore with great pleasure that in this Newsletter we have an interview with dr. Annemiek ter Heijne. Annemiek has obtained her PhD degree from Wageningen University on the topic of MFCs, performing her research within the Wetsus program. She became assistant professor at Wageningen University and is now mentoring PhD researchers with the program herself. She recently received a prestigious VENI scholarship from the Netherlands Organisation for Scientific Research (NWO).

Membranes are another important topic within the Wetsus program, and you can read as Prof.dr. Kitty Nijmeijer describes a novel way of membrane cleaning, with interesting new insights from the work of her former PhD student dr. Yusuf Wibisono.

The work performed at Wetsus has a global impact, and to further expand this impact, last September Wetsus became a member of the EU’s main climate innovation initiative, Climate-KIC. Here we have an interview with Climate-KIC CEO Bertrand Van Ee about how Wetsus’ research on water quality plays a vital role in mitigating climate change.

Bert Hamelers

Of course, this is only a small part of the work done by our PhD researchers. This shows from the fact that in 2014 more than 80 papers were published in the Wetsus program. You can find an overview here.

Enjoy reading the Wetsus S&T Newsletter of Spring 2015.

Bert Hamelers,

New partnership between Wetsus and Climate-KIC “a perfect fit”

As of September 2014, Wetsus has become an official member of Climate-KIC (Climate Knowledge and Innovation Community), the EU’s largest public-private climate innovation initiative. The new partnership will allow Wetsus to continue to expand its international influence far beyond Leeuwarden, bringing with it a wealth of knowledge and a model for innovation that has already proven very successful.

Created in 2010 by the European Institute of Innovation and Technology (EIT), Climate-KIC’s mission is to create new partnerships that transform innovative ideas into commercial products, services, and jobs, with the goal to mitigate and adapt to climate change. Wetsus hopes to connect with new partners in this way, in line with Climate-KIC’s efforts to integrate research, technology, and entrepreneurial business. Operating across 13 European centers, from London to Brussels to Berlin, along with regional centers on the outskirts of Europe, Climate-KIC has the breadth needed to create partnerships on all scales, often connecting private, public, and academic sectors.

Bertrand van Ee

Bertrand Van Ee, CEO of Climate-KIC, sees Wetsus as a key player in the Climate-KIC’s global water initiative, in large part because Wetsus and Climate-KIC share many of the same goals.

“Wetsus fits in perfectly with Climate-KIC,” Van Ee said. “Wetsus is a world-renowned institution, very similar to Climate-KIC. Wetsus brings together higher education, research, and business on a very specific topic, which is water quality. On a global scale, water is one of the grand challenges, and Wetsus is right in the middle of it.”

One reason for Wetsus’ central role in global water science is its “innovation model,” which allows it to attract large numbers of experts who contribute an enormous combined amount of knowledge. This knowledge would usually come at a high price, but the innovation model allows Wetsus to tap into this reservoir of expertise in an economical way.

“We wanted to know why the innovation model at Wetsus is so successful,” said Cees Buisman, Director of Wetsus and Professor at Wageningen University. “Wetsus has 65 PhD students from 52 professors—more professors than any other university in the world in this field. They are highly motivated because they are supervising their own PhD students. It’s an excellent way to receive lots of knowledge.”

Wetsus’ innovation model ties in very closely to the three main areas of Climate-KIC: innovation, education, and entrepreneurship. At Wetsus, the focus is on educating technical people to make them more business-oriented, so that they can turn their research into something useful in society as quickly as possible. One of Wetsus’ first start-ups, RedStack, which is producing electricity by mixing salt water and freshwater using reverse electrodialysis (RED), is a prime example of the success of this model.

By joining Climate-KIC, Wetsus has access to many more potential partnerships, allowing it to apply the innovation model on a much larger scale. By doing so, everyone—researchers, entrepreneurs, and the rest of society—can take full advantage of years of accumulated knowledge at universities and focus it on market-oriented developments.

combined logo europe climate-KIC

Van Ee is very excited about expanding Wetsus’ model throughout Climate-KIC’s network, as well.

“Wetsus has a really cool environment in Leeuwarden,” Van Ee said. “It is really a super duper building, really an inspiring environment that brings people in from all over the world. You get the best talent. Businesses have a keen interest in gaining access to that knowledge and getting their hands on new technology.”

In these cases where the technology is so new, much of the business takes the form of start-ups. For this reason, supporting start-ups plays a key component in Climate-KIC’s mission.

“Start-ups are very much the new business model,” Van Ee said. “That’s where the new employment comes from. You often see that it’s difficult to get commercialized in the climate market, which is still emerging. That’s what we’re focusing on, helping these start-ups get through their early phases, helping get their technology to market.”

“We call it ‘tough love,’” he explained of the way Climate-KIC supports start-ups. “It’s tough [for the start-up] to get to the next stage, to climb the next hurdle, but once you do, we’ll love you to bits.”

One challenge that start-ups must face is the controversy that often accompanies the climate change problem. However, Climate-KIC focuses much more on mitigating the devastating and indisputable consequences of severe weather events, which drive home the need for cost-effective resilience measures.

As a market of resilience, the emerging climate market focuses on mitigating the socioeconomic losses caused by extreme weather events. Worldwide losses have already reached $1.2 trillion per year, according to the DARA group, a European-based non-governmental organization. Resilience markets include areas such as adaptation, engineering and construction, and the agrifood sector, all of which are aimed at saving human life and infrastructure.

“Climate change is not so much about saving the world as it is about saving the people,” Van Ee said. “The world doesn’t need people, but people need the world.”

This global nature of climate change requires global partnerships, like that between Climate-KIC and Wetsus. By building on each other’s strengths, everyone benefits.

January–December 2014 map of temperature anomalies showing warmer-than-average temperatures across the vast majority of the globe (National Climatic Data Center)
January–December 2014 map of temperature anomalies showing warmer-than-average temperatures across the vast majority of the globe (National Climatic Data Center)

“Our ambition is to become more of a European institute than a Dutch institute,” Buisman said. “We want to grow our European relevance.”

By gaining access to the vast Climate-KIC network, Wetsus has unlimited opportunities for growth in new directions, and Climate-KIC has gained a vast source of scientific and entrepreneurial expertise.

“I think we can learn from each other and make each other stronger,” Van Ee said. “Wetsus has deep knowledge of water quality. By having Wetsus in the partnership, we are closing the full water cycle. We’re very excited about that. We will evaluate Wetsus to the level that they participate, whether that may be new start-ups coming out of Wetsus or breakthroughs in research.

“It’s great having Wetsus on board. I’m looking forward to a wonderful partnership.”

More information about Climate-KIC can be found at

Article written by Lisa Zyga, IL, USA

The science of bubbles leads to cleaner water purification membranes

Membrane processes, such as nanofiltration (NF) and reverse osmosis (RO), are commonly used for the production of our drinking water. But when the membranes used in these processes become clogged with microorganisms and various organic and inorganic material, these cleaning devices themselves need cleaning. In the latest research on membrane cleaning, Dr. Yusuf Wibisono, along with his PhD advisor Professor Kitty Nijmeijer at the University of Twente, and their coauthors have published two research papers and a review that demonstrate the effectiveness of physical techniques based on the use of air bubbles in removing fouling from membranes.

Dr. Yusuf Wibisono, together with Prof. Nijmeijer and Dr. Kemperman, holding his PhD degree for his thesis on two-phase flow
Dr. Yusuf Wibisono, together with Prof. Nijmeijer and Dr. Kemperman, holding his PhD degree for his thesis on two-phase flow

In their review, published in the Journal of Membrane Science, the scientists systematically analyzed the results of 195 papers published since 1989 that investigated the effectiveness of two-phase flow cleaning in membrane processes. Two-phase flow, which refers to the use of a gas and a liquid flowing in either the same or opposite directions, has an advantage over single-phase (liquid only) flow in that it creates instabilities within the flow. The instabilities sweep away fouling from membrane surfaces or feed spacers in spiral-wound membrane elements. The effectiveness of the gas bubbles on cleaning depends on many variables, such as gas flow rate, liquid flow rate, temperature, bubble-bubble interactions, bubble-particle interactions, and more. The scientists wanted to determine which conditions are optimal for membrane cleaning.

“We put all this data in a graph so that we could compare it and extract information that can be used to guide future research,” Nijmeijer said. “We showed which parameters are critical and determined the effectiveness of this cleaning method. For instance, we found that there are two conditions that are very important to be effective: good bubble distribution and the gas/liquid ratio, both important to obtain sufficient wall shear stress to create friction on the membrane surface. Because we did the review, we were able to identify the important parameters.”

The review is currently one of the top 10 most downloaded papers in the journal.

Using insight from the review, the researchers published another paper in the Journal of Membrane Science in which they experimentally demonstrated the effectiveness of optimizing bubble distribution and liquid velocity. The paper also accounted for effects such as the gas/liquid ratio, feed spacer geometry, and applied pressure on the efficiency of two-phase flow cleaning.

In their third paper, published in Water Research, the scientists expanded upon these results further, looking at how to make the technology even more effective. They demonstrated that hydrogel-coated polypropylene feed spacers can complement the two-phase flow method by preventing early attachment of biofilms, which is likely due to the strong hydrophilic nature and the negative charge of the hydrogel coating. Preventing early attachment is a key strategy in delaying biofilm growth over time.

Professor Nijmeijer demonstrates membrane technology in a lecture hosted by the University of the Netherlands
Professor Nijmeijer demonstrates membrane technology in a lecture hosted by the University of the Netherlands

Currently, biofouling control strategies in NF and RO membranes often use various chemical agents, such as alkalines, detergents, enzymes, chelating agents, acids, and biocides. Although chemical methods are useful to varying degrees, the chemicals often damage the membranes, are harmful to the environment, and, in the case of biocides, may promote the resistance of microorganisms to these biocides and worsen biofouling problems. Further, biofouling often quickly regrows after chemical cleaning because the dead bacteria that remain serve as nutrients for subsequent biofilm growth.
Because two-phase flow cleaning is a purely physical method, and chemical-free by nature, it could provide a powerful way to complement the chemical strategies and optimize biofouling control. Two-phase flow cleaning avoids the drawbacks of using chemicals, and because it removes and does not just kill bacteria, it can significantly reduce future biofilm growth. The researchers hope to build on these advantages even more in the future.

“There are many parameters contributing to the type and extent of biofouling, such as flow rate, temperature, and biology of the water,” Nijmeijer said. “The main point is always the biology. The biology has the annoying property that it can adapt itself to the conditions. If we change the temperature of the water, for example, we may get rid of one type but a new type of biology comes. This makes it incredibly difficult to control. The ultimate goal is to somehow control the biology, but this is probably impossible.”

The challenging nature of this work also makes it exciting, and Nijmeijer has made it one of her goals to share the most interesting aspects of membrane science throughout society. She has appeared several times on national television, including the show De Wereld Draait Door, which is watched by more than 1.5 million people daily. In February, the University of the Netherlands posted on its website five of her lectures on membrane technology, which she originally presented at Club Air in Amsterdam last December. The lectures (in Dutch, with English subtitles) can be viewed here.

“The research that I do in chemical engineering is just so fun, and it also constitutes a lot how we live,” she said. “Without the work that we in the scientific community do, we wouldn’t have clean water, energy, all the plastics, phones, everything that we use in our daily lives, cosmetics, shampoo, just to mention a few—all come from scientific developments. It’s so nice to share that with people. Research can be a bit scary to people. Sometimes they may think, ‘I don’t understand what you mean, but I believe you.’ Research is a puzzle, and I try to put it together so people can see the big picture. It’s very fun.”

Sometimes the opportunities for outreach are very spur of the moment, as happened just recently.

“Yesterday [March 18, 2015, red.] the National TV called again,” she said. “I didn’t plan that. They said, ‘can you be here in two hours?’ You never know when they may call!”

That evening, De Wereld Draait Door was celebrating the “Year of Einstein” because it has been exactly 100 hundred years since Einstein developed his famous theory of general relativity, in 1915. To mark the anniversary, Nijmeijer and three other scientists were invited to explain their favorite equation. Nijmeijer explained the ideal gas law (PV=nRT) and the beauty of thermodynamics.

Professor Nijmeijer talks about her favorite equation, the ideal gas law, to celebrate the “Year of Einstein” on the news show De Wereld Draait Door on 18 March 2015
Professor Nijmeijer talks about her favorite equation, the ideal gas law, to celebrate the “Year of Einstein” on the news show De Wereld Draait Door on 18 March 2015

Nijmeijer has also had many wonderful experiences collaborating with Wetsus, and has been involved with Wetsus personally since the beginning. At the time she was still assistant professor, the Membrane group of the University of Twente was one of the cofounders of Wetsus, and part of their work on membranes for water technology evolved into what Wetsus has become today. Currently Nijmeijer is head of the Membrane Science and Technology group at the University of Twente, and a PhD supervisor in the field of membrane research performed at Wetsus.

“Wetsus is a very inspiring environment,” she said. “It combines scientific, technological, and industrial research, covering a broad spectrum of disciplines, varying from microbiology to laser technology and from membranes to electrochemistry, all with a focus on water technology. The research is different than what is done in universities because in universities individual groups are much more focused on one specific fields of expertise. The multi-disciplinary aspect opens new directions for research, and as long as the research is sufficiently in-depth, this is a great thing. And they are very nice people. I really love to be there, always”.

Article written by Lisa Zyga, IL, USA

- Yusuf Wibisono, et al. “Two-phase flow in membrane processes: A technology with a future”. Journal of 
  Membrane Science 453 (2014) 566–602.
- Yusuf Wibisono, et al. “Biofouling removal in spiral-wound nanofilatration elements using two-phase flow cleaning”.
- Yusuf Wibisono, et al. “Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: A novel platform for eco-friendly biofouling mitigation”. Water Research 71 (2015) 171-186.

Microorganisms charge batteries using energy from wastewater

The term “wastewater” is a little misleading for Annemiek ter Heijne, who sees wastewater not as waste but as an untapped source of energy. This is because wastewater holds a large amount of biodegradable organic components, such as acetate, that contain chemical energy.

Pasfoto Annemiek klein

Ter Heijne, an assistant professor at Wageningen University and recent Wetsus alumna, is working on an innovative method to recover this energy that uses microorganisms to convert the organic matter into electricity and then store this electricity in a microbial battery.

This novel concept has recently earned ter Heijne a VENI grant, a highly acclaimed grant targeted at outstanding researchers at the start of their scientific careers, generally within three years of receiving a PhD.

“I think the interaction between microorganisms and electrodes is very promising because of the many areas of application that are possible,” ter Heijne said. “At the same time, it offers new ways for more fundamental studies because one can control the energy that is available to the microbes in a very precise way. I find it very fascinating that these microorganisms occur everywhere and that they are able to generate electricity in a very efficient way”.

Ter Heijne has been investigating methods of recovering energy from wastewater using microbial fuel cells (MFCs) and bioelectrochemical systems (BESs) for several years, and it was also the subject of her PhD thesis. Since then, her research group of seven PhD students has recently obtained a proof-of-principle of a novel concept: the bio-charging and discharging of small, porous grains of carbon called “capacitive granules” in an electrochemical cell.

The capacitive granules form the core of the new microbial battery. Electrochemically active microorganisms that are present in many environments, including the wastewater itself, can charge the capacitive granules by extracting electrons from the organic compounds in wastewater, and then store the electrons using the high surface area of the pores of the granules. In order to maintain electroneutrality, protons and other cations in the wastewater are attracted to the granules and accumulate both in the pores and around the outer surface of the granules.

Microorganisms in an electroactive active biofilm (blue) charge a capacitive granule (black) by converting organic compounds, such as acetate, into CO2, protons, and electrons. The electrons are stored in the capacitive granules. At the same time, cations accumulate around the particle and inside the biofilm.
Microorganisms in an electroactive active biofilm (blue) charge a capacitive granule (black) by converting organic compounds, such as acetate, into CO2, protons, and electrons. The electrons are stored in the capacitive granules. At the same time, cations accumulate around the particle and inside the biofilm.

Once the granules are charged, they are transported from the wastewater to a discharge cell by, for example, a gas flow. Once inside the discharge cell, they can be stored or discharged at a high rate and efficiency, and used to generate electricity.

Because this idea is very different from the way most microbial fuel cells function, one of the main goals of ter Heijne’s research group is to develop a test cell in which a single electrode can be characterized. They will then combine these results with a model of the biological charging and discharging in order to better understand the interaction between the microorganisms and capacitive electrodes. Whereas most microbial fuel cells use flat-plate designs, in which the electrodes consist of flat plates, the new design combines the flat-plate system with a capacitive charging reactor containing the wastewater and carbon granules.

Although the technology is in its early stages, it appears to be very promising. In a recent paper published in Environmental Science & Technology, the scientists demonstrated a proof-of-principle in which they showed that adding activated carbon granules to MFCs can be used to recover electricity from wastewater. The challenge is now to use the storage capacity of the granules to their full extent, so that the rates and energy recovery increase further.

Due to the encouraging results, the scientists hope that this new design may hold the key to a breakthrough in the development of bioelectrochemical systems, which could open the doors to a variety of practical applications. Two of the most important applications may be wastewater treatment and energy recovery. A review published in Science in 2012 estimates that the energy in wastewater in an industrialized society is equivalent to about 5% of the electricity production. In addition to electricity production, other applications of BESs include hydrogen production and nutrient and metal recovery.

Microbial battery concept: Carbon granules are charged in the charging reactor by electrochemically active microorganisms, which extract electrons from wastewater and store these electrons in the granules. The granules are then transported to the discharge cell, for example, by a gas flow, where they are discharged at high rate and efficiency.
Microbial battery concept: Carbon granules are charged in the charging reactor by electrochemically active microorganisms, which extract electrons from wastewater and store these electrons in the granules. The granules are then transported to the discharge cell, for example, by a gas flow, where they are discharged at high rate and efficiency.

Working in these directions, ter Heijne and her coauthors have recently published a review in Environmental Science: Water Research & Technology in which they analyzed the possibility of using BESs for nitrogen removal from wastewater. Unlike the conventional method of nitrogen removal, BESs do not reduce reactive nitrogen to inert N2 gas, but instead they separate the reactive nitrogen from the wastewater so that it can be recovered and reused. The recovered ammonia (NH3), for example, can be used as a fertilizer, as an energy source, or for any other purpose. This method is specifically interesting for urine, which contains high organics and high nitrogen concentrations. Overall, the method provides a three-for-one deal: it cleans wastewater, recovers nitrogen, and produces energy in the form of electricity or hydrogen.

“One of the topics I also see big opportunities for in the future is the use of electrical energy input to drive the reduction of CO2 to methane at the cathode,” ter Heijne added. “For this process, we use microorganisms at the cathode that can use electricity to produce methane. In this way, we can generate a fuel (methane) from electricity and CO2 as the only sources. This is a next-generation technology, as an alternative to the power-to-gas processes, in which hydrogen is generated in electrolysis cells, and this hydrogen is used to convert CO2 to methane at high temperatures”.

Collaborating with Wetsus will be an important component of ter Heijne’s work, as Wetsus plans to implement capacitive MFC technology in a pilot plant within the new few years.

“For the pilot plant, we are now designing and studying a larger reactor at Wetsus to find out the optimal conditions to demonstrate the capacitive electrodes,” ter Heijne said.

As ter Heijne explained, she has a long history with Wetsus, and plans to continue collaborating in the future.

“I did my PhD thesis at Wetsus, where I studied more efficient electricity generation by improving the cathodic reduction reaction in microbial fuel cells,” she said. “Currently, four PhD students out of my team of seven work at Wetsus on several topics: the reactor design for the capacitive electrodes, the competition between electrogens and methanogens, nitrogen recovery from urine, and copper recovery from mining wastewaters (these last two are connected to European projects). I am also co-supervisor of a PhD student at Minho University (in Braga, Portugal) who studies the microbiology of the system that recovers energy from urine. I very much enjoy creating a link between different disciplines to get to better understanding of these bioelectrochemical processes”.

Article written by Lisa Zyga, IL, USA

- M. Rodriguez Arredondo, et al. “Bioelectrochemical systems for nitrogen removal and recovery from wastewater”. Environmental Science: Water Research & Technology. 2015, 1, 22-33.
- Alexandra Deeke, et al. “Fluidized Capacitive Bioanode As a Novel Reactor Concept for the Microbial Fuel Cell”. Environmental Science & Technology 2015, 49, 1929-1935.

combining scientific excellence with commercial relevance