The urgent need for environmental sustainability has increasingly prompted policy makers to emphasize resource recovery from desalination brine streams. Recent research on resource recovery from waste streams has shown rising momentum with near term viability for several new technologies. In this perspective, we focus on new opportunities for metal resource recovery from seawater desalination brine, while outlining associated sustainability challenges and opportunities. The potential of metals recovery is discussed.

Technologies for selective metal ion separation from water and wastewater are currently attracting strong research interest as a pathway to greater sustainability. The chemistry of metal ion separation processes is critical for understanding the mechanisms of selectivity and making the technologies viable. This paper discusses current advances and challenges in metal ion separation technologies from chemical points of view and proposes how they should be approached in the future.

ADVERTISEMENT RETURN TO ISSUEPREVViewpointNEXTCaustic Soda Production, Energy Efficiency, and ElectrolyzersAmit Kumar*Amit KumarDepartment of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States*Email: [email protected]More by Amit Kumarhttps://orcid.org/0000-0001-7807-3427, Fengmin DuFengmin DuDepartment of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United StatesLaboratory for Physical Chemistry, ETH Zurich, CH-8093 Zurich, SwitzerlandMore by Fengmin Duhttps://orcid.org/0000-0002-8164-7628, and John H. Lienhard V*John H. Lienhard VDepartment of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States*Email: [email protected]More by John H. Lienhard Vhttps://orcid.org/0000-0002-2901-0638Cite this: ACS Energy Lett. 2021, 6, 10, 3563–3566Publication Date (Web):September 15, 2021Publication History Received27 August 2021Published online15 September 2021Published inissue 8 October 2021https://doi.org/10.1021/acsenergylett.1c01827Copyright © 2021 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views1621Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSUBJECTS:Radiology,Electrodes,Membranes,Electrical energy,Selectivity Get e-Alerts

Surface chemistry is known to influence the formation, composition, and electroactivity of electron-conducting biofilms. However, understanding of the evolution of microbial composition during biofilm development and its impact on the electrochemical response is limited. Here we present voltammetric, microscopic and microbial community analysis of biofilms formed under fixed applied potential for modified graphite electrodes during early (90 h) and mature (340 h) growth phases. Electrodes modified to introduce hydrophilic groups (-NH2, -COOH and -OH) enhance early-stage biofilm formation compared to unmodified or electrodes modified with hydrophobic groups (-C2H5). In addition, early-stage films formed on hydrophilic electrodes are dominated by the gram-negative sulfur-reducing bacterium Desulfuromonas acetexigens while Geobacter sp. dominates on -C2H5 and unmodified electrodes. As biofilms mature, current generation becomes similar, and D. acetexigens dominates in all biofilms irrespective of surface chemistry. Electrochemistry of pure culture D. acetexigens biofilms reveal that this microbe is capable of forming electroactive biofilms producing considerable current density of > 9 A/m2 in a short period of potential-induced growth (~19 h following inoculation) using acetate as an electron donor. The inability of D. acetexigens biofilms to use H2 as a sole source electron donor for current generation shows promise for maximizing H2 recovery in single-chambered microbial electrolysis cell systems treating wastewaters.

ADVERTISEMENT RETURN TO ISSUEPREVViewpointNEXTLithium Recovery from Oil and Gas Produced Water: A Need for a Growing Energy IndustryAmit Kumar*Amit KumarDepartment of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United StatesDepartment of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States*E-mail: [email protected]More by Amit Kumarhttp://orcid.org/0000-0001-7807-3427, Hiroki FukudaHiroki FukudaDepartment of Materials Engineering, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4More by Hiroki Fukuda, T. Alan HattonT. Alan HattonDepartment of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United StatesMore by T. Alan Hattonhttp://orcid.org/0000-0002-4558-245X, and John H. Lienhard V*John H. Lienhard, VDepartment of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States*E-mail: [email protected]More by John H. Lienhard, Vhttp://orcid.org/0000-0002-2901-0638Cite this: ACS Energy Lett. 2019, 4, 6, 1471–1474Publication Date (Web):June 5, 2019Publication History Received10 April 2019Accepted3 May 2019Published online5 June 2019Published inissue 14 June 2019https://pubs.acs.org/doi/10.1021/acsenergylett.9b00779https://doi.org/10.1021/acsenergylett.9b00779article-commentaryACS PublicationsCopyright © 2019 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views32299Altmetric-Citations101LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (1 MB) Get e-AlertscloseSUBJECTS:Adsorption,Lipids,Metals,Organic polymers,Wastewater Get e-Alerts

The electrochemically-mediated amine regeneration (EMAR) process uses electrons to modulate amine capacity to achieve CO2 separation from flue gas as an alternative to the traditional thermal regeneration process for CO2 capture. The EMAR separation scheme is validated in a batch system designed to evaluate efficiency losses. Current and voltage responses of the electrochemical process were analyzed in a flow system operated continuously for up to 50 h. An isothermal EMAR system can achieve separation efficiencies above 80% from a 15% CO2 feed, which is representative of the CO2 composition in a flue gas. This bench scale continuous system can operate at 40-80 kJ(e)/molCO(2) with an amine regeneration of between 0.12 and 0.62 mol(CO2)/mol(amine). The ability to separate CO2 at high electron utilization and moderate electrical energy consumption will prompt future research into optimization of the electrochemical separation unit to obtain long-term and stable operations for flue gas scrubbing.

In the version of this Perspective originally published, authors Amit Kumar and Katherine R. Phillips should have had a note in the affiliations indicating that they are equally contributing authors; this has now been corrected.

The rising use of seawater desalination for fresh water production is driving a parallel rise in the discharge of high-salinity brine into the ocean. Better utilization of this brine would have a positive impact on the energy use, cost, and environmental footprint of desalination. Furthermore, intermittent renewable energy can easily power the brine utilization and, for reverse osmosis technology, the entire desalination plant. One pathway toward these goals is to convert the otherwise discharged brine into useful chemicals; waste could be transformed into sodium hydroxide or caustic soda (NaOH) and hydrochloric acid (HCl). In this Minireview, we discuss opportunities and challenges for integrated valorization of desalination brine through NaOH and HCl recovery.

The ability to increase pH is a crucial need for desalination pretreatment (especially in reverse osmosis) and for other industries, but processes used to raise pH often incur significant emissions and nonrenewable resource use. Alternatively, waste brine from desalination can be used to create sodium hydroxide, via appropriate concentration and purification pretreatment steps, for input into the chlor-alkali process. In this work, an efficient process train (with variations) is developed and modeled for sodium hydroxide production from seawater desalination brine using membrane chlor-alkali electrolysis. The integrated system includes nanofiltration, concentration via evaporation or mechanical vapor compression, chemical softening, further ion-exchange softening, dechlorination, and membrane electrolysis. System productivity, component performance, and energy consumption of the NaOH production process are highlighted, and their dependencies on electrolyzer outlet conditions and brine recirculation are investigated. The analysis of the process also includes assessment of the energy efficiency of major components, estimation of system operating expense and comparison with similar processes. The brine-to-caustic process is shown to be technically feasible while offering several advantages, that is, the reduced environmental impact of desalination through lessened brine discharge, and the increase in the overall water recovery ratio of the reverse osmosis facility. Additionally, best-use conditions are given for producing caustic not only for use within the plant, but also in excess amounts for potential revenue.

As global desalination capacity continues its rapid growth, the impetus for reducing the adverse environmental impacts of brine discharge grows concurrently. Although modern brine outfall designs have significantly limited such impacts, they are costly. Recovering valuable components and chemical derivatives from brine has potential to resolve both environmental and economic concerns. In this article, methods for producing sodium hydroxide (“caustic”) from seawater reverse osmosis (SWRO) brine for internal reuse, which typically involve brine purification, brine concentration, and sodium chloride electrolysis, are reviewed. Because process energy consumption drives process cost and caustic purity determines product usability in drinking water systems, reviewed technologies are benchmarked against thermodynamic minimum energy consumption and maximum (stoichiometric) NaOH production rates. After individual reviews of brine purification, concentration, and electrolysis technologies, five existing facilities ...

Electron transfer between microorganisms and an electrode — even across long distances — enables the former to live by coupling to an electronic circuit. Such a system integrates biological metabolism with artificial electronics; studying these systems adds to our knowledge of charge transport in the chemical species involved, as well as, perhaps most importantly, to our knowledge of charge transport and chemistry at the cell–electrode interfaces. This understanding may lead to microbial electrochemical systems finding widespread application, particularly in the energy sector. Bioelectrochemical systems have already shown promise for electricity generation, as well as for the production of biochemical and chemical feedstocks, and with improvement are likely to give rise to viable applications. Electrodes colonized by microbial electrocatalysts can serve as useful components in the electrosynthesis of valuable chemical products. This Review outlines the mechanisms by which electrons are transferred between microorganisms and electrodes, and describes the challenges involved in designing robust and efficient systems.

When I first arrived in Belgium to begin my Ph.D. studies, I wasn't sure how I would survive without my friends and family back in northern India. I had chosen to pursue my doctoral studies at Ghent University because of its unique biological engineering program, but I expected that living in a new country would be challenging. I was right. I had a hard time eating the unfamiliar food (on several occasions I didn't eat at all) and often struggled to overcome everyday obstacles, such as navigating public transportation and interacting with salespeople. ![Figure][1] ILLUSTRATION: ROBERT NEUBECKER > “Being in an unfamiliar culture … aided my research career.” What I hadn't realized was how hard it would be on me emotionally. I felt extremely out of place and isolated. I was hesitant to explore anything unfamiliar, nervous that my ignorance of local norms would lead to embarrassment. A few times I reluctantly went dancing with friends, but I stuck to the sidelines because I didn't know how to salsa, cha-cha, or do any of the other dances everyone else seemed to know. For the most part, I did only what I had to do: I found a place to live and got started on my research project. I felt discouraged at work, too. I wanted to be productive, but my personal struggles and the typical challenges of starting graduate school got in the way. I now realize that I was trying to rush things, but at the time, my lack of research progress made me feel even more discouraged about my decision to go to grad school abroad. Several times I felt like giving up and flying home. But slowly, as I became friends with fellow graduate students from around the world, my outlook began to change. I saw how my friends from Italy and Spain threw themselves into the new culture without fear—happy to try new foods, learn about unfamiliar customs, and laugh and be laughed at. As I saw my friends take risks, I decided to take the leap and adopt their mindset. The next time we went dancing, I got out on the floor—even though I knew I would get some of the steps wrong—and I had a great time. As my newfound confidence grew, I began to push further outside my comfort zone. I initiated conversations with strangers despite my relatively poor grasp of the language and accepted invitations for weekend group trips. I began to appreciate that there can be many “right” ways to think and behave, and that I could feel at home anywhere as long as I allowed myself to become part of the community. At first, I didn't think about how this change in perspective might affect my work, but now I realize that many of the qualities I developed to deal with being in an unfamiliar culture—an openness to learning new things, an ability to appreciate and communicate with people from different backgrounds, and a greater comfort with uncertainty and change—have also aided my research career. Over the course of my training, I have followed my intellectual curiosity from environmental engineering to biological engineering to chemistry to applied microbiology to chemical engineering. I think I would have had a hard time successfully crossing these scientific borders if I hadn't had the experience of adapting to new settings in my personal life. These qualities have also helped prepare me to take on leadership roles outside the lab, which are personally rewarding and hopefully will strengthen my applications for jobs in the future. Taking on responsibility as the energy and environment chair of the Massachusetts Institute of Technology Energy Club, for example, was somewhat intimidating at first, but by looking at it as another challenge to my adaptation skills, I have been able to dive in headfirst. Even though going abroad for my degree was difficult at first, I'm so glad I did it. Since that time, I have studied in 11 more countries and visited 35 others. Together, these experiences have made me a better person, both personally and professionally, and that is a benefit I never expected when I first set foot in Belgium 12 years ago. [1]: pending:yes

Management of Municipal Solid Waste (MSW) has become a major challenge in India. The green house gases primarily methane (50-55%) and carbon dioxide (40-45%), which are emitted from the MSW dumpsites are major concerns in the national emission budget. The MSW, if managed properly, can be used as a resource for energy recovery. The Sanitary landfill gas mainly constitutes of methane (50-55%) and carbon dioxide (40-45%). Both these green house gases which are also termed as bio energy are released from municipal solid waste landfill by the process of biodegradation of the organic matter present in the municipal solid waste that is dumped in sanitary landfill. It basically involves the conversion of the complex carbohydrates which are present in organic matter to energy. Bio-energy is also known as biofuel which could be effectively utilized as an alternative for conventional fossil fuel. This helps in the reduction in ozone depleting green house gases emitted into the atmosphere and thus solves the problem of the global warming. This review paper deals with the characteristics, economic and environmental benefits of the bioenergy gases emitted from sanitary landfill.

Harnessing, and understanding the mechanisms of growth and activity of, biofilms of electroactive bacteria (EAB) on solid electrodes is of increasing interest, for application to microbial fuel and electrolysis cells. Microbial electrochemical cell technology can be used to generate electricity, or higher value chemicals, from organic waste. The capability of biofilms of electroactive bacteria to transfer electrons to solid anodes is a key feature of this emerging technology, yet the electron transfer mechanism is not fully characterized as yet. Acetate oxidation current generated from biofilms of an EAB, Geobacter sulfurreducens, on graphite electrodes as a function of time does not correlate with film thickness. Values of film thickness, and the number and local concentration of electrically connected redox sites within Geobacter sulfurreducens biofilms as well as a charge transport diffusion co-efficient for the biofilm can be estimated from non-turnover voltammetry. The thicker biofilms, of 50 ± 9 μm, display higher charge transport diffusion co-efficient than that in thinner films, as increased film porosity of these films improves ion transport, required to maintain electro-neutrality upon electrolysis.

In microbial electrochemical cells the anode potential can vary over a wide range, which alters the thermodynamic energy available for bacterial-electrode electron exchange (termed electroactive bacteria). We investigated how anode potential affected the microbial catalytic response of the electroactive biofilm. Microbial biofilms induced to grow on graphite electrodes by application of a fixed applied anode potential in membrane-separated and membrane-less electrochemical cells show differences in electrocatalytic response. Maximum current density is obtained using +0.2V vs. Ag/AgCl to induce biofilm growth in membrane-less cells, in contrast to a maximum achieved at lower applied potentials in a membrane-separated electrochemical cell configuration. This insight into differences in optimal applied potentials based on cell configuration can play an important role in selection of parameters required for microbial fuel cells and bio-electrochemical systems.