Science & Technology newsletter, April 2017
Articles in this edition:
- Interview with Associate Prof. Louis de Smet on organic chemistry and water technology
- Harvesting blue energy with the breathing cell
- Investigating the diet of worms
- Bacteria used to sweeten sour gas
Guest editorial by Michele Tedesco, Wetsus Theme Coordinator
Wetsus is growing fast. In the last months we have witnessed a large number of excellent achievements, including conferences, new projects, publications, and prestigious grants. Any attempt to list all of these successes in such a brief editorial would not do them justice. As a recent example, the International Conference on Membranes in Drinking and Industrial Water Production (organized by the European Desalination Society and Wetsus) brought more than 130 experts in membrane science to Leeuwarden in February. The success of this event demonstrates once again the role of Wetsus as an international hub in the field of water technology.
A further recognition of the high-quality research performed at Wetsus is given by the increasing funds received from the European Commission. Three new exciting projects have been granted since June 2016 (Resourcing Water, MEDUWA-Vecht, BAoBaB), bringing to seven the total number of EU-funded projects currently running at Wetsus. The success rate for obtaining these grants is around 3%, which shows that Wetsus is an excellent research institute in Europe.
Key elements of such a successful story are the multidisciplinary environment, the interest in bringing technologies to the market, and the close collaboration with universities and industrial partners. All of these elements are clearly represented in the articles of this newsletter.
We are pleased that prof. Louis de Smet from Wageningen University recently joined Wetsus as research advisor. In this edition of the newsletter, Louis will share with us his thoughts on phosphate removal and his research on selective coatings, a line of research he started thanks to winning a prestigious ERC grant.
Dr. Pawel Roman, scientist at Wetsus, will talk about the use of bacteria to remove sulphurous compounds from sour gases. The research performed by Pawel and his co-workers led to the development of the first full-scale biodesulfurization system that uses only sulfur-oxidizing bacteria for the sweetening process. Recently, Pawel has also started a company to develop new sensors for sulphide measurement under high-pH conditions.
Jordi Moreno, PhD student at Wetsus, will give us the latest updates in the field of Blue Energy, i.e., the process of harvesting renewable energy by mixing seawater and fresh water. In particular, Jordi will introduce the concept of the “breathing cell” as a novel design to increase the process performance and reduce biofouling. Jordi, who is currently finishing his PhD thesis and holds a part-time job at REDstack, was awarded the Special Marcel Mulder Price for Partnership in 2016, in recognition of his laudable example of close collaboration between Wetsus and industrial partners.
Bob Laarhoven, PhD student at Wageningen University, will present his project on “investigating the diet of worms” in order to develop a sustainable worm biomass production for the fish industry. By combining expertise in wastewater technology, aquaculture and aquatic biology, Bob and his co-workers aim to produce a fish feed that is not contaminated with heavy metals, micropollutants, or pathogens. Besides his role as PhD student, in 2016 Bob started a company (Dutch Blackworms) for the development of a large-scale worm biomass production system for the fish industry.
Our agenda for the coming months is already full of exciting events. For the complete list, please check the Wetsus calendar here. Above all, we are looking forward to the upcoming PhD defenses of Pau Rodenas Motos and Joao Sousa next week (April 21st).
I hope you enjoy reading the Wetsus S&T Newsletter of Spring 2017!
Interview with Associate Prof. Louis de Smet on organic chemistry and water technology
Louis de Smet, an associate professor at Wageningen University, specializes in organic chemistry, and one of the many areas that he is applying this knowledge to is water technology. Since receiving the ERC Consolidator Grant a little over a year ago, de Smet has been expanding his research team, and together they are cooperating closely with Wetsus to bring their research to the front of advanced desalination and wastewater treatment methods.
In this interview, de Smet describes some of his latest research on chemical sensors, including a nanoscale device that can detect TNT explosives and a chemical attachment system for phosphate removal, as well as ongoing research on polymer coatings for the detection of volatile water pollutants.
Question: What are some of the research projects you’re working on right now?
Louis de Smet: My expertise is on the modification of surfaces with molecules to control and tune their properties. Often, we first synthesize or functionalize molecules before subjecting them to physisorption or chemisorption strategies. Over the past decade, I have been mainly working on sensor projects where the resulting molecular coatings, sometimes composites, act as a so-called affinity layer. These layers are prepared onto a transducer platform and, upon their interaction with an analyte, this input signal is converted into, for instance, an electrical or optical signal. For many applications it is crucial to have an affinity layer that interacts with specifically one analyte. To facilitate or even tune the process of recognition, a molecular receptor is added. Organic chemists have a toolbox of synthetic approaches available to change the structure of (receptor) molecules and hence also the way they interact with other molecules or ions, the targets.
Since a few years, we also have been applying our surface modification engineering strategies to membrane-related applications. After all, in the case of separation processes, recognition plays an important role.
Q: Can you describe the research in your recent papers in the journals of Nano Letters and Soft Matter?
LDS: Together with researchers from the University of Twente, Philips Research and the University of Melbourne, we made an electrical nanodevice that can detect TNT, an explosive molecule. In this case, the affinity layers consist of molecular cages, the receptors, that each can host one TNT molecule. This work was featured on the cover of the first 2017 issue of Nano Letters. Apart from the progress we made in terms of selectivity, I am particularly happy with this paper as it shows the importance of cross-interdisciplinary collaborations: we could only achieve this by combing experimental and computational chemistry, electrical engineering and nanofabrication.
In our Soft Matter paper we describe the chemical attachment of a phosphate receptor to a polymer. Although not 100% selective yet, coatings containing this functionalized polymer did show a preference for phosphate. Early March I presented a follow-up study on this work at the 5th International Conference on Multifunctional, Hybrid and Nanomaterials in Lisbon. In this work we have put the functionalized polymer onto iron oxide nanoparticles to study the uptake of phosphate at a pH value that met those of typical wastewater.
|Polymer phosphate formula|
Where TNT is detected and phosphate absorbed or collected, I now also work on using molecular systems like these to specifically remove, harvest and recover certain ions from (waste) water. Apart from adding and tuning the selectivity of the coating, another benefit of the surface chemistries we work on is related to the level of control when it comes to the coating thickness. This can range from several nanometers to hundreds of micrometers. The required thickness depends on the application.
Q: When did you receive the ERC grant, and how are you using it (or how do you plan to use it)?
LDS: I’ve obtained an ERC Consolidator Grant in late 2015 to work on the design and preparation of materials that can be used to remove and, ultimately, recover high-value nutrients from (waste) water. The main focus is on phosphate, but other targets like heavy metals, lithium or sodium are very interesting as well. Building further on our Soft Matter study, we not only aim to improve the selectivity for phosphate, but we also wish to tune the binding reversibility: after all, the selective removal should be followed by a release. In this research program we combine organic chemistry, surface chemistry and advanced water treatment methods to meet this challenge.
From an organizational point of view, this five-year program allows me to hire four PhD students and a part-time technician. Additionally, the grant covers investments for the purchase of new equipment, including a so-called Quartz Crystal Microbalance. With this technique we measure the change in frequency of a quartz crystal resonator when materials adsorb on it. From this shift we can obtain the change in mass at a sensitivity of ng/cm2. The equipment has been installed in our labs last month and we plan to use it to study the coating preparation as well as the uptake or release of nutrients to/from these coatings.
Q: When and why did you begin collaborating with Wetsus? How are you connected to Wetsus now? And how do you think this connection to Wetsus has helped you in your research?
LDS: My first contacts with Wetsus date from 2008 when I worked at TU Delft. Within the theme of Sensoring, we started a project on using polymer coatings for the detection of volatile water pollutants. Most technologies for the detection of volatile organic compounds (VOCs) in water make use of the principle that VOCs distribute themselves between the aqueous phase and the gas phase just above it. By analyzing the gas phase, something can be said about the presence of certain VOCs in the water. We worked on a capacitive sensor device to detect VOCs directly in the water. We prepared a hydrophobic polymer coating onto the device, and tested its affinity to a series of VOCs. An ongoing project aims to integrate this type of layer with a coax sensor, a platform with low noise levels and high sensitivities.
Several years ago I also become active within the theme of Desalination and we currently work on phosphate-selective membranes and sodium-selective materials. As of this year, I work at Wetsus one day per week as an advisor on materials for sustainable water technology. This does not only enable me to combine studying fundamental interface issues with applied research, aiming to improve existing water treatment technologies, but I strongly believe this multidisciplinary approach is also a good recipe for breeding new strategies for tackling some of the most important global challenges along the themes of water scarcity and the depletion of natural resources.
Q: What is your perspective of the current research going on in the field of water science and technology? And what areas of water research do you think will be most exciting in the future?
LDS: I believe material science and materials engineering will become of increasing importance for various water treatment technologies. What I mean is that new organic materials, molecules, whether or not combined with inorganic matter, will be designed, made and integrated into these technologies, to meet several of the big challenges in the field: increasing selectivity and stability and reduction or even prevention of fouling. Clearly, within my research program the focus is on membranes and separation, related to desalination techniques, but on a more fundamental level: more knowledge on controlling and tuning interfacial properties may also boost some other water-related technologies, like blue energy and sensor systems, given the importance of the transport of charges (ions and/or electrons).
Also, I realize I still talk about water treatment technologies, but it is broader than that: the focus is not only on water. Wastewater is resource water and more and more attention will be given to closing the loops of water and its often high-value impurities as well as to increase the use of sustainable energy in the related technologies.
Cabrera-Rodríguez, Carlos I.; Laura Paltrinieri, Louis C.P.M. de Smet; Luuk A. M. van der Wielen; Adrie J. J. Straathof. “Recovery and esterification of aqueous carboxylates by using CO2-expanded alcohols with anion exchange.” Green Chemistry (2017) 19, 729-738
Cao, Zh.; P.I. Gordiichuk, K. Loos, E.J.R. Sudhölter and L.C.P.M. de Smet. “The effect of guanidinium functionalization on the structural properties and anion affinity of polyelectrolyte multilayers.” Soft Matter (2016) vol. 12, 1496-1505
Harvesting blue energy with the breathing cell
Membranes that appear to “breathe” by expanding and compressing like a pair of lungs could better harvest electricity through reverse electrodialysis (RED) stacks, increasing the net power production and bringing blue energy technology a step closer to commercialization.
University of Twente PhD student Jordi Moreno and his Wetsus colleagues are pioneering the breathing cell concept at REDstack—Wetsus’ spin-off company, which is working to harvest the energy available from the salinity difference between seawater and river water.
In the first experimental tests of the breathing cell, the researchers demonstrated that a breathing stack achieves a maximum net power density of 1.3 W/m2 over a broad range of flow rates. This value is close to the maximum net power density ever reported, 1.5 W/m2, which was obtained only for a very narrow flow rate range.
The breathing cell’s potential improvements arise from the fact that it addresses one of the major bottlenecks of current RED stacks, which is that river water (which has a low conductivity) is a major contributor to the overall resistance of the stack. This can be reduced by decreasing the river water channel thickness, but this is at the cost of a higher hydraulic loss.
A conventional RED stack consists of alternating channels of river water and seawater, with each channel separated by alternating cation and anion exchange membranes that allow for the passage of either positive or negative charges, respectively. As the river water and seawater flow through the channels, the chemical potential difference between them generates a voltage over the membranes.
Principle of the breathing cell: In stage 1, both seawater and river water flow through compartments of equal widths. In stage 2, the seawater outlet valves are closed, leading to a pressure build-up in the compartment. In stage 3, the pressure build-up leads to the expansion of the seawater compartment. Because of this expansion, the river water compartment is compressed, leading to a smaller intermembrane distance. In stage 4, the valves open and eventually the pressure decreases and the compartments return to their initial positions.
In current versions of the technology, the membranes are kept at a fixed distance by placing spacers between the membranes. In the breathing cell concept, by contrast, the membrane distance is not fixed by the spacer. The researchers replaced the spacer in the river water compartments by a spacer with an unequal thickness, thicker at the inlet and thinner at the working part of the stack. And by using pressure, the researchers can control the intermembrane distance.
When both river water and seawater flow through the compartments, the membranes are spaced equally as before, with an intermembrane distance of 480 µm. But when the seawater outlet is closed, pressure builds up in the seawater compartments, causing the flexible membranes to expand outward and compress the river water compartments down to a width of 120 µm. The key consequence is that the narrower river water compartments generate less resistance, resulting in a higher power density. (The wider seawater compartment is not a problem since seawater contributes very little to resistance due to its high salinity.) Afterwards, the seawater outlet is opened again, releasing the pressure and expanding the river water compartment again allowing the river water to be refreshed with a lower hydraulic loss. This opening and closing of the seawater outlet is happening with a frequency in the order of seconds.
“The breathing cell is a game changer for RED because it is the first time that we move the membranes inside the stacks,” Moreno said. “We change from using fixed configurations toward dynamic configurations. And it is not only for RED, it is also a game changer for ED stacks. The movement of the membranes give us the freedom to adapt the movement frequency to the fouling conditions of the feed waters. So it can harvest more energy at different flow regimes, and is also a perfect antifouling strategy.”
The breathing cell concept is part of Moreno’s PhD thesis, which is titled “Fouling management and new stack design for RED.” The rest of the thesis is dedicated to fouling—specifically, understanding the interactions of the different foulants with the membranes and studying new antifouling strategies.
“One new antifouling strategy that we studied was the use of CO2 saturated water as a two-phase flow technique,” Moreno said. “What does this mean? That we are using the same effect of opening a bottle of champagne or Coca-Cola to clean the particles deposited in the membranes. We do this by introducing our CO2-saturated water inside the stack and, due to a loss of pressure, the CO2 dissolved in water nucleates, creating really small bubbles and also lowering the pH inside. This method is more efficient, in terms of cleaning, than the current one using air sparging.”
Moreno plans to finish his PhD by the end of the year, and in the meantime, he has started a part-time job at REDstack. Reflecting on the past few years, Moreno explained that his experience at Wetsus has proved to be better than he ever could have expected, both professionally and personally.
“Wetsus gave me the opportunity, besides becoming a better researcher, to do a lot of training about personal development,” Moreno said. “Through these experiences, I learned how to better handle everyday situations and be less stressed and more productive. I am also part of the Blue Energy team, a team very well involved in the project that always gives a lot of freedom for creativity and listens to the opinions of the PhD students. And last but not least, my thesis project is led by Prof. Kitty Nijmeijer. I always enjoy our conversations about the project, where I not only learn about science and research, but also about personal development.”
Jordi Moreno shows his experiments to King Willem-Alexander during the inauguration of REDstack’s Blue Energy Pilot Plant at Afsluitdijk in November 2014.
J. Moreno, E. Slouwerhof, D. A. Vermaas, M. Saakes, and K. Nijmeijer. “The Breathing Cell: Cyclic Intermembrane Distance Variation in Reverse Electrodialysis.” Environ. Sci. Technol., 2016, 50 (20), pp 11386–11393
Investigating the diet of worms
Anyone who enjoys a good seafood dinner will appreciate what Bob Laarhoven, a PhD student at Wageningen University, has been working on with his colleagues at Wetsus: analyzing the diet of the worm Lumbriculus variegatus, which is eaten by many carnivorous fish such as salmon and trout.
Based on his research results, Laarhoven is also spearheading a start-up company called Dutch Blackworms with the goal of developing a large-scale worm biomass production system for the fish industry—and ultimately, a more sustainable way to grow some of the most popular edible fish.
An important requirement in the aquaculture industry is to use fish feed that is not contaminated with heavy metals, micropollutants, or pathogens. One way to ensure this, is to grow the worms on a diet of organic material produced by waste streams from the food industries.
In a paper published in a recent issue of PLOS ONE, Laarhoven and his colleagues have reported on the development of a standardized agar sediment test that can determine which waste streams make good “worm food” based on their concentrations of protein and other nutrients that L. variegatus needs to thrive. Laarhoven’s test evaluates the worm growth performance of different waste streams and identifies which streams produce the greatest amount of worm biomass.
“The standardized agar sediment test makes it possible to control the growth conditions independently of the quality of the food,” Laarhoven said. “This could never be done without the addition of agar gel. Worms in these test setups have outstanding growth rates in comparison with other available test setups.”
|Aquatic worm reactor for controlled worm production.|
This ability to raise fast-growing worms also has potential applications in research areas beyond the development of worm biomass production systems.
“I am hoping that this method will be noticed and accepted by scientists working in the field of eco-toxicology, because worms are excellent bio-indicators but test designs used nowadays never induce much growth,” Laarhoven said.
In another recent study, published in the Journal of Insects as Food and Feed, Laarhoven and his coauthors have shown that L. variegatus will grow and reproduce on organic waste streams produced by wheat processing byproducts from the food industry.
“Our work shows that worms are able to grow on a diet that only contains vegetable proteins—something which was never clear before,” Laarhoven said. “Also it reveals that sugars are not that important. It’s all about protein and fat level.”
Although the worms’ growth and reproduction rates were not as high as on a control diet containing a commercial fish feed, the use of wheat byproducts suggests a promising path toward developing a future worm biomass production system.
To bring these research results to the greater benefit of society, Laarhoven founded Dutch Blackworms on July 1, 2016.
“Dutch Blackworms is a start-up established by me and Hellen Elissen (former Wetsus employee and worm specialist),” Laarhoven said. “We believe that the mass production of aquatic worms using waste streams from the food industry makes good business, as there is a strong need for high-quality proteins for aquaculture feeds.”
At this moment, the company is increasing its worm stock to an amount needed for the first commercial production. The plan is to first sell the worms to wholesalers dealing with live feeds for ornamental fish owners, and then to commercial fish feed producers.
The inspiration for Dutch Blackworms, along with all of the research that makes it possible, is the type of multidisciplinary project that flourishes in an environment like that of Wetsus, Laarhoven explained.
“Wetsus is an amazing institute with a lot of resources that allow PhD students to design their research in ways that are normally more restricted,” he said. “This means that the results at Wetsus are often very impressive. The multi-disciplinary character and experts around allow you to get support from all kind of fields. For me this was really important as I combined wastewater technology, aquaculture and aquatic biology in one project. It changed my way of thinking, and I am more creative than ever before—not afraid anymore to combine different fields of expertise.”
While continuing his research and advancing Dutch Blackworms, Laarhoven also plans to complete his PhD later this year. In addition, he currently works on wastewater research and also has his hands full with two young children.
“Besides being and staying a happy dad, I am trying to spend most of my time extending the company,” he said. “I started a new job at the University of Groningen, working on the detection of cellulose in wastewater and the re-use of cellulose recovered from our own municipal wastewaters. The job is coming to an end, which allows me to spend more time on finalizing my PhD research and establishing Dutch Blackworms even more.”
The proposed sustainable solution for fish farming begins with waste streams from the food industries and ends with high-quality fish (farmed eels eating a block of frozen blackworms). Credit: Bob Laarhoven
Laarhoven B, Elissen HJH, Temmink H, Buisman CJN (2016) “Agar Sediment Test for Assessing the Suitability of Organic Waste Streams for Recovering Nutrients by the Aquatic Worm Lumbriculus variegatus.” PLoS ONE 11(3): e0149165.
B. Laarhoven, H.J.H. Elissen, C.J.N. Buisman, H. Temmink. “The carbon to nitrogen ratio in isoenergetic wheat based diets controls the growth rate of the aquatic worm Lumbriculus variegatus.” Journal of Insects as Food and Feed: 2 (4) - Pages: 225 – 231.
Bacteria used to sweeten sour gas
By harnessing the power of billions of sulfur-hungry bacteria, Wetsus scientist Paweł Roman and his colleagues are developing new ways to clean “sour gas” by removing toxic substances that contribute to steel corrosion and air pollution.
When gases such as natural gas, landfill gas, and petroleum gas contain a large amount of hydrogen sulfide, thiols, and other organosulfur compounds, they are considered “sour.” Because of their adverse effects, these sulfurous compounds need to be removed from sour gas streams in a process called “sweetening.”
Roman first became interested in sulfur chemistry while working on his master’s degree at the Gdańsk University of Technology in Poland. He attended the university from 2006 to 2011, where he received a bachelor’s degree in Applied Chemistry and a master’s degree by completing a thesis on airborne research titled “Chemistry and transport of pollutants in cumulus cloud water.”
In November 2011, Roman started a PhD project on sulfur chemistry guided by the sub-department of Environmental Technology at Wageningen University. He performed his PhD project at Wetsus, graduating in May 2016. Now he works as a post-doctoral researcher at Wetsus where, among other responsibilities, he supervises a follow-up sulfur project.
Roman explained that the challenges of working with sulfur were partly what drew him toward the subject in the first place.
“During my first contact with thiols while doing my master studies, I realized that sulfur chemistry is very complex and not very popular among scientists, as it is usually associated with an unfriendly environment, i.e., sulfur compounds are often very smelly and toxic,” Roman said. “Also, measuring sulfur compounds can be problematic as many of them are unstable. I always liked challenges, so the possibility of further work with sulfur during my PhD research was very attractive to me. Actually, it was a double challenge for me, as biology is strongly involved in this project, which was quite new for me at that time.”
In his most recent work, Roman and his colleagues have focused on using bacteria to remove sulfurous compounds from sour gas. Traditionally, removal of these compounds involves physicochemical processes, which are often expensive, energy-intensive and leave relatively large leftover “tails.”
There are several advantages of using sulfur-oxidizing bacteria to break down the toxic substances into safer ones. Compared to physicochemical processes, the biocatalytic activity of microbes is efficient at very low micro-molar concentrations, low temperatures, and atmospheric pressure, which leads to lower costs. In addition, microbe-based processes do not require chemical chelating agents or produce sulfide-containing waste streams.
|Lab-scale sulfide-oxidizing bioreactor. Image credit: Anne Hennig.|
In one recent paper published in Environmental Science & Technology, Roman and his coauthors experimentally demonstrated a full-scale biodesulfurization system that relies solely on sulfur-oxidizing bacteria to cleanse a sour gas stream of thiols, which are toxic organosulfur compounds.
The researchers found that different types of thiols (such as methanethiol, ethanethiol, and propanethiol) cause shifts in the composition of the microbial community, as the different thiols provide competitive advantages to various populations. Most importantly for industrial applications, the acclimatized populations are able to oxidize enough sulfide to elemental sulfur to allow the bioreactor to achieve stable operation, even under the continuous addition of thiols.
In the same study, the researchers also identified several negative effects of diorgano polysulfanes on the bioreactor controlling system. The results indicated the need for a new controlling strategy based on a new sensor. Roman and his colleagues have recently developed the first prototype of a sensor for robust sulfide measurement under high pH conditions. Currently, Roman is starting a company that will develop an industrial version of the sensor and bring it to market.
In a related work published in Water Research, Roman and his collaborators investigated the bacteria’s sulfur-oxidizing mechanism on a cellular level, for the first time identifying the reaction kinetics and ways in which thiols inhibit the oxidation process. This deeper understanding of the microbial-thiol interactions will lead to designing and optimizing future full-scale biodesulfurization reactors.
|Lab-scale sulfide-oxidizing bioreactor: the “milky liquid” is a solution of biologically produced colloidal sulfur particles from H2S. Image credit: Pawel Roman.|
Although sour gas is Roman’s primary focus at the moment, in the past year he has also contributed to studies on microbial physiology and ecology in hypersaline environments. In two such studies, both published in Nature’s ISME Journal (the International Society for Microbial Ecology), the researchers reported on the surprising discoveries of two new groups of obligately anaerobic sulfur-reducing extremely halophilic archaea, whose existence challenges the traditional views on these prokaryotes.
The first of the two groups obtains its energy in a way that has never been observed before in the entire Archaea domain. It uses acetate as an electron donor with sulfur as an electron acceptor, forming sulfide and CO2 as the only products.
The second group of anaerobic haloarchaea uses formate or hydrogen as electron donors and elemental sulfur, thiosulfate, or dimethylsulfoxide as electron acceptors. The researchers explain that this advanced metabolic plasticity and type of respiration has never before been seen in this type of microbe, and it enables the microbes to flourish in a wide variety of saline environments. Roman discovered that, apart from the main products, both groups also release a minor fraction of thiols in the gas phase and produce polysulfides as an intermediate product.
Looking toward the future, Roman is excited about new directions in water purification and cutting-edge molecular tools.
“In the field of waste water purification, the strategy is shifting from solely purification to added values of recovered pollutants which are often valuable, such as heavy metals, biogens, granular sludge, etc.,” Roman said. “Also, Nereda technology, the EPS-producing consortia selected in the aerobic granual sludge system, is a very promising technology to replace the conventional waste water purification technology. In addition, the modern development of molecular tools makes it possible to analyze the microbial community composition of very complex consortia involved in the full-scale waste water purification systems, which provides a better opportunity to control the system.”
|Synthesis of diorgano polysulfanes later used for quantification of polysulfide anions. Image credit: Pawel Roman.|
Pawel Roman et al. “Selection and Application of Sulfide Oxidizing Microorganisms Able to Withstand Thiols in Gas Biodesulfurization Systems.” Environ. Sci. Technol., 2016, 50 (23), pp 12808–12815.
Pawel Roman et al. “Inhibition of a biological sulfide oxidation under haloalkaline conditions by thiols and diorgano polysulfanes.” Water Research.
Dimitry Y Sorokin et al. “Elemental sulfur and acetate can support life of a novel strictly anaerobic haloarchaeon.” The ISME Journal (2016) 10, 240–252.
Dimitry Y Sorokin et al. “Discovery of anaerobic lithoheterotrophic haloarchaea, ubiquitous in hypersaline habitats.” The ISME Journal. Advance online publication.