Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Resilience of roof-top Plant-Microbial Fuel Cells during Dutch winter
    Helder, M. ; Strik, D.P.B.T.B. ; Timmers, R.A. ; Reas, S.M.T. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2013
    Biomass and Bioenergy 51 (2013). - ISSN 0961-9534 - p. 1 - 7.
    time-domain reflectometry - electricity production - temperature - performance - biofilm
    The Plant-Microbial Fuel Cell (P-MFC) is in theory a technology that could produce sustainable electricity continuously. We operated two designs of the P-MFC under natural roof-top conditions in the Netherlands for 221 days, including winter, to test its resilience. Current and power densities are not stable under outdoor conditions. Highest obtained power density was 88 mW m-2, which is lower than was achieved under lab-conditions (440 mW m-2). Cathode potential was in our case dependent on solar radiation, due to algae growth, making the power output dependent on a diurnal cycle. The anode potential of the P-MFC is influenced by temperature, leading to a decrease in electricity production during low temperature periods and no electricity production during frost periods. Due to freezing of the roots, plants did not survive winter and therefore did not regrow in spring. In order to make a sustainable, stable and weather independent electricity production system of the P-MFC attention should be paid to improving cathode stability and cold insulation of anode and cathode. Only when power output of the Plant-Microbial Fuel Cell can be increased under outdoor conditions and plant-vitality can be sustained over winter, it can be a promising sustainable electricity technology for the future
    Improving medium chain fatty acid productivity using chain elongation by reducing the hydraulic retention time in an upflow anaerobic filter
    Grootscholten, T.I.M. ; Steinbusch, K.J.J. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2013
    Bioresource Technology 136 (2013). - ISSN 0960-8524 - p. 735 - 738.
    clostridium-kluyveri - carboxylic-acids - ethanol - biomass - fermentation - inhibition - reduction
    The expansion of biofuel production can lead to an array of negative environmental impacts. Therefore, the European Union (EU) has recently imposed sustainability criteria on biofuel production in the Renewable Energy Directive (RED). In this article, we analyse the effectiveness of the sustainability criteria for climate change mitigation and biodiversity conservation. We first use a global agriculture and forestry model to investigate environmental effects of the EU member states National Renewable Energy Action Plans (NREAPs) without sustainability criteria. We conclude that these targets would drive losses of 2.2 Mha of highly biodiverse areas and generate 95 Mt CO 2 eq of additional greenhouse gas (GHG) emissions. However, in a second step, we demonstrate that the EU biofuel demand could be satisfied ‘sustainably’ according to RED despite its negative environmental effects. This is because the majority of global crop production is produced ‘sustainably’ in the sense of RED and can provide more than 10 times the total European biofuel demand in 2020 if reallocated from sectors without sustainability criteria. This finding points to a potential policy failure of applying sustainability regulation to a single sector in a single region. To be effective this policy needs to be more complete in targeting a wider scope of agricultural commodities and more comprehensive in its membership of countries.
    High rate heptanoate production from propionate and ethanol using chain elongation
    Grootscholten, T.I.M. ; Steinbusch, K.J.J. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2013
    Bioresource Technology 136 (2013). - ISSN 0960-8524 - p. 715 - 718.
    castor-oil - bacteria - acetate - acids
    Heptanoate (or enanthate), a saturated mono-carboxylate with seven carbon atoms, is a commercially produced biochemical building block with versatile applications. Currently, heptanoate is mainly derived from the oxidation of heptaldehyde, which can be obtained after pyrolysis of castor oil. The objective of this investigation was to achieve efficient high rate heptanoate production using a mixed culture chain elongation process based on propionate and ethanol. An efficient high rate heptanoate production using chain elongation could offer an alternative for heptanoate production from castor oil. The investigation was performed in an upflow anaerobic filter with a hydraulic retention time of 17 h. A heptanoate production rate of 4.5 g l-1 d-1 was achieved with a heptanoate concentration of 3.2 g l-1. These results show sufficient potential to consider this approach as an alternative for heptanoate production from castor oil. Future research should make heptanoate production from propionate and ethanol more cost-effective.
    Bioelectrochemical production of caproate and caprylate from acetate by mixed cultures
    Eerten-Jansen, M.C.A.A. van; Heijne, A. ter; Grootscholten, T.I.M. ; Steinbusch, K.J.J. ; Sleutels, T.H.J.A. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2013
    ACS sustainable chemistry & engineering 1 (2013)5. - ISSN 2168-0485 - p. 513 - 518.
    microbial electrolysis cells - fuel-cells - hydrogen - biomass - conversion - ethanol - reduction - transport - membranes - butyrate
    The use of mixed cultures to convert waste biomass into medium chain fatty acids, precursors for renewable fuels or chemicals, is a promising route. To convert waste biomass into medium chain fatty acids, an external electron donor in the form of hydrogen or ethanol needs to be added. This study investigated whether the cathode of a bioelectrochemical system can be used as the electron donor for the conversion of acetate into medium chain fatty acids. We show that medium chain fatty acids were produced in a bioelectrochemical system at -0.9 V vs. NHE cathode potential, without addition of an external mediator. Caproate, butyrate and smaller fractions of caprylate were the main products formed from acetate. In-situ produced hydrogen was likely involved as an electron donor for the reduction of acetate. Electron and carbon balances revealed that 45% of the electrons in electric current and acetate, and 31% of the carbon from acetate were recovered in the formed products. This study showed for the first time production of medium chain fatty acids caproate and caprylate from acetate at the cathode of bioelectrochemical systems, and offers new opportunities for application of bioelectrochemical systems.
    Promoting chain elongation in mixed culture acidification reactors by addition of ethanol
    Grootscholten, T.I.M. ; Kinsky dal Borgo, F. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2013
    Biomass and Bioenergy 48 (2013). - ISSN 0961-9534 - p. 10 - 16.
    clostridium-kluyveri - liquid fuels - fatty-acids - solid-waste - hydrolysis - digestion - cellulose - biomass
    In this research we investigate a microbial production process to produce medium chain fatty acids (MCFAs) based on the organic fraction of municipal solid waste (OFMSW). In this microbial production process, called chain elongation, bacteria produce medium chain fatty acids (MCFAs) from ethanol and volatile fatty acids (VFAs). MCFAs could be used as new biomass based building blocks for the chemical and fuel industry. The objective of this article is to investigate whether chain elongation can be promoted during acidification of OFMSW by addition of ethanol. The results show that chain elongation can be promoted during acidification of OFMSW by addition of ethanol. However, the hydrolysis rate and the carboxylic acid yield of the OFMSW in reactors with ethanol additions were lower than the hydrolysis rate and the carboxylic acid yield than in reactors without ethanol additions. Further research is required to determine whether a combined chain elongation and acidification reactor or a separated reactor system is more advantageous for MCFA production from OFMSW.
    Electricity generation by a novel design tubular plant microbial fuel cell
    Timmers, R.A. ; Strik, D.P.B.T.B. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2013
    Biomass and Bioenergy 51 (2013). - ISSN 0961-9534 - p. 60 - 67.
    exchange membranes - iron reduction - rice plants - rhizodeposits - performance - resistance - transport - bacteria
    The tubular plant microbial fuel cell was designed to increase the feasibility of this technology. To test the new setup two anode materials were investigated, namely a graphite felt and graphite granules. The average power output based on membrane area was 10 mW m-2 for felt, and 12 mW m-2 for graphite granules. The corresponding mass and volume power densities for the felt were 15 and 69 times greater than for the granules. This showed that a decrease in the use of anode electrode material is possible while achieving comparable power outputs per square meter of membrane. These findings make future applications of the plant microbial fuel cell technology more feasible due to costs reduction per kWh. Furthermore, this PMFC design could be likely applied into soils without the need to excavate the topsoil.2
    Chain elongation of acetate and ethanol in an upflow anaerobic filter for high rate MCFA production
    Grootscholten, T.I.M. ; Steinbusch, K.J.J. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2013
    Bioresource Technology 135 (2013). - ISSN 0960-8524 - p. 440 - 445.
    mixed cultures - liquid fuels - reactor - digestion - caproate - hydrogen - biomass - waste
    Recently, interest has regained for medium chain fatty acids (MCFAs) as a low cost feedstock for bio-based chemical and fuel production processes. To become cost-effective, the volumetric MCFA production rate by chain elongation should increase to comparable rates of other fermentation processes. We investigate the MCFA production process at a hydraulic retention time of 17 h in an upflow anaerobic filter to improve the volumetric MCFA production rate. This approach resulted in a MCFA production with a volumetric production rate of 16.6 g l-1 d-1, which is more than seven times higher than the current production rate. Moreover the rate is now in the range of other fermentation processes like methane, butanol and ethanol production. Increasing the ethanol load lead to higher volumetric production rates and a high MCFA selectivity of 91%. During operation, methane percentages lower than 0.1% were detected in the headspace of reactor.
    Electricity production with living plants on a green roof: Environmental performance of the Plant-Microbial Fuel Cell
    Helder, M. ; Chen, Wei-Shan ; Harst, E.J.M. van der; Strik, D.P.B.T.B. ; Hamelers, H.V.M. ; Buisman, C.J.N. ; Potting, J. - \ 2013
    Biofuels Bioproducts and Biorefining 7 (2013)1. - ISSN 1932-104X - p. 52 - 64.
    life-cycle assessment - design
    Several renewable and (claimed) sustainable energy sources have been introduced into the market the during the last centuries in an attempt to battle pollution from fossil fuels. Especially biomass energy technologies have been under debate for their sustainability. A new biomass energy technology was introduced in 2008: the Plant-Microbial Fuel Cell (PMFC). In this system electricity can be generated with living plants and thus bioelectricity and biomass production can be combined on the same surface. A green roof producing electricity with a P-MFC could be an interesting combination. P-MFC technology is nearing implementation in the market and therefore we assessed the environmental performance of the system with an early stage Life Cycle Assessment (LCA). The environmental performance of the P-MFC is currently worse than of conventional electricity production technologies. This is mainly due to the limited power output of the P-MFC and the materials presently used in the P-MFC. Granular activated carbon (anode material), goldwires (current collectors) and Teflon coated copper wires (connecting anode and cathode) have the largest impact on the environmental performance. Use of these materials needs to be reduced or avoided and alternatives need to be sought. Increasing power output and deriving co-products from the P-MFC will increase environmental performance of the P-MFC. At this stage it is too early to compare the PMFC with other (renewable) energy technologies since the P-MFC is still under development.
    Electricity from the Afsluitdijk
    Buisman, C.J.N. ; Baptist, M.J. ; Hamelers, H.V.M. - \ 2012
    The flat-plate plant-microbial fuel cell: the effect of a new design on internal resistances
    Helder, M. ; Strik, D.P.B.T.B. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2012
    Biotechnology for Biofuels 5 (2012). - ISSN 1754-6834
    electricity - performance - growth
    Due to a growing world population and increasing welfare, energy demand worldwide is increasing. To meet the increasing energy demand in a sustainable way, new technologies are needed. The Plant-Microbial Fuel Cell (P-MFC) is a technology that could produce sustainable bio-electricity and help meeting the increasing energy demand. Power output of the P-MFC, however, needs to be increased to make it attractive as a renewable and sustainable energy source. To increase power output of the P-MFC internal resistances need to be reduced. With a flat-plate P-MFC design we tried to minimize internal resistances compared to the previously used tubular P-MFC design. With the flat-plate design current and power density per geometric planting area were increased (from 0.15 A/m(2) to 1.6 A/m(2) and from 0.22 W/m(2) to and 0.44 W/m(2)) as were current and power output per volume (from 7.5 A/m(3) to 122 A/m(3) and from 1.3 W/m(3) to 5.8 W/m(3)). Internal resistances times volume were decreased, even though internal resistances times membrane surface area were not. Since the membrane in the flat-plate design is placed vertically, membrane surface area per geometric planting area is increased, which allows for lower internal resistances times volume while not decreasing internal resistances times membrane surface area. Anode was split into three different sections on different depths of the system, allowing to calculate internal resistances on different depths. Most electricity was produced where internal resistances were lowest and where most roots were present; in the top section of the system. By measuring electricity production on different depths in the system, electricity production could be linked to root growth. This link offers opportunities for material-reduction in new designs. Concurrent reduction in material use and increase in power output brings the P-MFC a step closer to usable energy density and economic feasibility.
    Effect of additional charging and current density on the performance of Capacitive energy extraction based on Donnan Potential
    Liu, F. ; Schaetzle, O. ; Sales, B.B. ; Saakes, M. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Energy & Environmental Science 5 (2012)9. - ISSN 1754-5692 - p. 8642 - 8650.
    pressure retarded osmosis - water salinity difference - reverse electrodialysis - power-generation - gradient power - river water - sea
    The difference in the salt concentrations of river and seawater implies that wherever they mix, energy could be extracted from the salinity gradient. This is a renewable and clean means of generating energy that makes use of a natural process. Capacitive energy extraction based on the Donnan potential (CDP) is a promising technique for extracting this energy. We herein describe our investigation of the effect of additional charging on extraction behaviour using a forced current density. The study was conducted in a flow-through cell, using capacitive electrodes and ion exchange membranes. It is shown that increasing the accumulated charge in the system could be beneficial in terms of energy extraction. Furthermore, the addition of charge improved the power densities achieved. By charging at higher current densities and discharging at lower current densities, the performance of the system may be improved. The highest average power density achieved in this study was 0.205 +/- 0.006 W m(-2) (1.26 +/- 0.75 mW g(-1)). This was obtained using a charge of 6 C (4.62 C g(-1)), with a controlled constant current of 50 mA (38.5 mA g(-1) or 6.24 A m(-2)). Three main limiting factors to the performance of CDP were identified, namely (i) the voltage drop over time, caused by the self-discharge of the cell and the non-ideal behaviour of the membranes, (ii) the duration of the switching times and (iii) the loss over the internal resistance. Of these, the internal resistance was identified as being the most important parameter to be minimized in order to further improve the performances of CDP systems.
    Faster Time Response by the Use of Wire Electrodes in Capacitive Salinity Gradient Energy Systems
    Burheim, O.S. ; Liu, F. ; Sales, B.B. ; Schaetzle, O. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    The Journal of Physical Chemistry Part C: Nanomaterials and Interfaces 116 (2012)36. - ISSN 1932-7447 - p. 19203 - 19210.
    pressure-retarded osmosis - reverse electrodialysis - power - extraction - water - sea - performance - density
    Capacitive energy extraction based on Donnan potential (CDP) and capacitive energy extraction based on double layer expansion (CDLE) are novel electroctrochemical processes to convert the potential free energy of mixing sea and river water into electric work. This is done by the use of supercapacitor electrodes with and without ion exchange membranes. Currently, these techniques rely on improved mass transport in order to become more efficient and give higher power output. In this paper we evaluate the transport phenomena by diffusion and the electrode geometry when switching between sea and river water at open circuit potential (OCP). By changing the electrode geometry from a flat plate to a cylindrical one, experiments and analytical models in combination show that mass transport by diffusion is increased. This is demonstrated without any changes in the hydrodynamic conditions. Improving mass transport without changing the hydrodynamic conditions breaks with what has been the convention in the scientific community of salinity gradient power. Moreover, in sea water the transport phenomena appear to be controlled by diffusion, and the response time for building open circuit potential in CDP and CDLE under this condition is reduced by a factor of 2 when using wire electrodes instead of flat plate electrodes. In river water, the trend is similar though the response time is generally larger.
    Impact of Wire Geometry in Energy Extraction from Salinity Differences Using Capacitive Technology
    Sales, B.B. ; Burheim, O.S. ; Liu, F. ; Schaetzle, O. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Environmental Science and Technology 46 (2012)21. - ISSN 0013-936X - p. 12203 - 12208.
    pressure retarded osmosis - reverse electrodialysis - water desalination - renewable energy - power production - river water - electrodes - sea - deionization - gradients
    Energy extraction based on capacitive Donnan potential (CDP) is a recently suggested technique for sustainable power generation. CDP combines the use of ion-exchange membranes and porous carbon electrodes to convert the Gibbs free energy of mixing sea and river water into electric work. The electrodes geometry has a relevant impact on internal resistance and overall performance in CDP. In this work, we present the first effort to use wire shaped electrodes and its suitability for improving CDP. Analytical evaluation and electrical measurements confirm a strong nonlinear decrease in internal resistance for distances between electrodes smaller than 3 mm. We also demonstrated that we get more power per material invested when compared to traditional flat plate designs. These findings show the advantages of this design for further development of CDP into a mature technology.
    Exploiting the spontaneous potential of the electrodes used in the capacitive mixing technique for the extraction of energy from salinity difference
    Brogioli, D. ; Ziano, R. ; Rica, R.A. ; Salerno, D. ; Kozynchenko, O. ; Hamelers, H.V.M. ; Mantegazza, F. - \ 2012
    Energy & Environmental Science 5 (2012)12. - ISSN 1754-5692 - p. 9870 - 9880.
    gradient power - water - desalination - adsorption - battery - supercapacitor - performance - storage - salt
    The "capacitive mixing" (CAPMIX) technique is aimed at the extraction of energy from the salinity difference between the sea and rivers. It is based on the voltage rise that takes place at the electrodes when changing the salt concentration of the solution in which the two electrodes are dipped. In this paper, we focus on activated carbon electrodes, produced with various methods and treatments, and we measure their behaviour in CAPMIX experiments. We find that they behave as polarizable electrodes only on time scales of the order of minutes, while on longer time scales they tend to move to a specific "spontaneous" potential, likely due to chemical redox reactions. This analysis sheds light on the charge leakage, i.e. the loss of the stored charge due to undesired chemical reactions, which is one of the main hurdles of the CAPMIX technique when performed with activated carbon electrodes. We show that the leakage finds its origin in the tendency of the electrode to move to its spontaneous potential. Our investigation allows us to completely get rid of the leakage and demonstrates the striking result that CAPMIX cycles can be performed without an external power supply.
    Electrochemical characterization of a supercapacitor flow cell for power production from salinity gradients
    Sales, B.B. ; Liu, F. ; Schaetzle, O. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Electrochimica Acta 86 (2012). - ISSN 0013-4686 - p. 298 - 304.
    energy - electrodes - water - sea
    Salinity gradients could be a great source of energy in the future. Capacitive energy extraction based on Donnan Potential (CDP) is a new technique to directly convert this energy into electricity. COP uses a supercapacitor-like device combining ion exchange membranes and capacitive materials to adsorb and desorb ions with the Donnan Potential of the membranes as only driving force. The resulting current can be extracted through an external load. In this study, traditional electrochemical techniques: galvanostatic charge-discharge and cyclic voltammetry were used to investigate intrinsic properties of this open system. This study demonstrates the feasibility to characterize the capacitive behavior of the cell in low concentration (0.5 M). Presence of membranes, as well as the possibility of having the electrolyte flowing through the cell was investigated. In the studied cell, the presence of membranes showed a limitation by the anion exchange membrane at low current densities but no effect at high current densities. The flow rate did not influence the capacitance of the system either.
    Capacitive Bioanodes Enable Renewable Energy Storage in Microbial Fuel Cells
    Deeke, A. ; Sleutels, T.H.J.A. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2012
    Environmental Science and Technology 46 (2012)6. - ISSN 0013-936X - p. 3554 - 3560.
    performance - power
    We developed an integrated system for storage of renewable electricity in a microbial fuel cell (MFC). The system contained a capacitive electrode that was inserted into the anodic compartment of an MFC to form a capacitive bioanode. This capacitive bioanode was compared with a noncapacitive bioanode on the basis of performance and storage capacity. The performance and storage capacity were investigated during polarization curves and charge discharge experiments. During polarization curves the capacitive electrode reached a maximum current density of 1.02 +/- 0.04 A/m(2), whereas the noncapacitive electrode reached a current density output of only 0.79 +/- 0.03 A/m(2). During the charge discharge experiment with S min of charging and 20 min of discharging, the capacitive electrode was able to store a total of 22 831 C/m(2), whereas the noncapacitive electrode was only able to store 12 195 C/m(2). Regarding the charge recovery of each electrode, the capacitive electrode was able to recover 52.9% more charge during each charge discharge experiment compared with the noncapacitive electrode. The capacitive electrode outperformed the noncapacitive electrode throughout each charge discharge experiment. With a capacitive electrode it is possible to use the MFC simultaneously for production and storage of renewable electricity.
    Proceedings 2nd international PlantPower Symposium 2012
    Strik, D.P.B.T.B. ; Reas, S. ; Helder, M. ; Mos, Y. ; Schrama, N. ; Steinbusch, K.J.J. ; Wetser, K. ; Fennema, S. ; Snel, J. ; Kuijken, R. ; Hamelers, H.V.M. - \ 2012
    Wageningen : Wageningen University, Sub-deparment of Environmental Technology - 122
    The effect of different control mechanisms on the sensitivity and recovery time of a microbial fuel cell based biosensor
    Stein, N.E. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2012
    Sensors and Actuators B: Chemical 171-172 (2012). - ISSN 0925-4005 - p. 816 - 821.
    oxygen-demand sensor - performance - toxicity
    Biosensors can be used detect toxicity and monitor quality of drinking water. A microbial fuel cell (MFC) based biosensor can be used to detect toxicity. Changes in water quality, as indicated by changes in cell voltage, are usually measured using an external resistance. The authors are not aware of any rationale for the choice of the magnitude of the resistance used, nor of any evidence that this method of control results in the optimal sensitivity of the sensor. The influence of the magnitude of the external resistance on the sensitivity and recovery time of the MFC-based biosensor was therefore investigated. A low resistance resulted in a large change in signal and a more sensitive sensor, while a high resistance resulted in a shorter recovery time. Furthermore, instead of an external resistor, a potentiostat was used to control anode potential or a galvanostat was used to control the electrical current. With these two types of control it was possible to detect the presence of a toxic component. A significant change in signal was observed in the sensor where anode potential was controlled. Surprisingly negative currents were also observed. When current was controlled the anode potential decreased in the presence of a toxic component as opposed to the resistor-controlled sensor in which anode potential increased in the presence of a toxic component. The recovery times of the sensors under both anode potential control and current control were found to be longer than when an external resistor was used.
    Influence of membrane type, current and potential on the response to chemical toxicants of a microbial fuel cell based biosensor
    Stein, N.E. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2012
    Sensors and Actuators B: Chemical 163 (2012)1. - ISSN 0925-4005 - p. 1 - 7.
    ion-exchange membranes - industrial waste-water - vibrio-fischeri - biocatalyzed electrolysis - activated-sludge - performance - transport - toxicity - sensor - wastewaters
    Drinking water free of chemical toxicants is important for people's health. A microbial fuel cell based biosensor can be used to detect the presence of toxic chemicals. The sensitivity of this type of biosensor for nickel was investigated. There was no delay in the response of the sensor and the sensitivity was 0.0027 A/m2/mg Ni/l at an anode potential of -0.4 V. The effect of four types of ion exchange membranes (cation exchange, anion exchange, monovalent cation exchange and bipolar membranes) on the sensitivity was not significant. Current density correlates with the decrease of the nickel concentration in the sensor with 16.5 mg/l/A/m2 by causing a flux of nickel towards the membrane and the catholyte. However, the sensitivity is higher at higher overpotential and thus at higher current density. Thus although nickel concentration is lower, the response is higher at high overpotentials. The sensitivity still has to be increased because even at an overpotential of -0.16 V the sensitivity is too low to be able to measure the concentrations that is maximally allowed by European directives on (drinking) water quality.
    Effect of hydrogen and carbon dioxide on carboxylic acids patterns in mixed culture fermentation
    Arslan, D. ; Steinbusch, K.J.J. ; Diels, L. ; Wever, H. De; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Bioresource Technology 118 (2012). - ISSN 0960-8524 - p. 227 - 234.
    acidogenic fermentation - biohydrogen production - anaerobic-bacteria - waste-water - fatty-acids - degradation - communities - inhibition - hydrolysis - industrial
    This study investigated the carboxylate spectrum from mixed culture fermentation of three organic waste streams after supplying 2 bar hydrogen and carbon dioxide or a mixture of these two gases to the headspace. Under any modified headspace, propionate production was ceased and butyrate, caproate and the total carboxylate concentrations were higher than in the reactors with N2 headspace (control). Production of one major compound was achieved under hydrogen and carbon dioxide mixed headspace after 4 weeks of incubation. Both the highest acetate concentration (17.4 g COD/l) and the highest fraction (87%) were observed in reactors with mixed hydrogen and carbon dioxide headspace independent of the substrate used. In the control reactor, acetate made up maximum 67% of the total products. For other products, the highest concentration and fraction were seldom observed together. Selective butyrate production reaching a 75% fraction was found under the carbon dioxide headspace on the carbohydrate rich waste.
    Bioelectrochemical Systems: An Outlook for Practical Applications
    Sleutels, T.H.J.A. ; Heijne, A. ter; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    ChemSusChem 5 (2012)6. - ISSN 1864-5631 - p. 1012 - 1019.
    microbial fuel-cells - electricity-generation - oxygen reduction - waste-water - fe(iii)-reducing bacterium - biohydrogen production - hydrogen-production - electrolysis cells - exchange membrane - power-generation
    Bioelectrochemical systems (BESs) hold great promise for sustainable production of energy and chemicals. This review addresses the factors that are essential for practical application of BESs. First, we compare benefits (value of products and cleaning of wastewater) with costs (capital and operational costs). Based on this, we analyze the maximum internal resistance (in mO¿m2) and current density that is required to make microbial fuel cells (MFCs) and hydrogen-producing microbial electrolysis cells (MECs) cost effective. We compare these maximum resistances to reported internal resistances and current densities with special focus on cathodic resistances. Whereas the current densities of MFCs still need to be increased considerably (i.e., internal resistance needs to be decreased), MECs are closer to application as their current densities can be increased by increasing the applied voltage. For MFCs, the production of high-value products in combination with electricity production and wastewater treatment is a promising route.
    Ammonium recovery and energy production from urine by a microbial fuel cell
    Kuntke, P. ; Smiech, K.M. ; Bruning, H. ; Zeeman, G. ; Saakes, M. ; Sleutels, T.H.J.A. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2012
    Water Research 46 (2012)8. - ISSN 0043-1354 - p. 2627 - 2636.
    afvalwaterbehandeling - urine - huishoudens - ammonium - denitrificatie - afvalwaterbehandelingsinstallaties - microbiële brandstofcellen - energieterugwinning - waste water treatment - urine - households - ammonium - denitrification - waste water treatment plants - microbial fuel cells - energy recovery - perfluorosulfonic membranes - bioelectrochemical systems - performance - transport - ph
    Nitrogen recovery through NH3 stripping is energy intensive and requires large amounts of chemicals. Therefore, a microbial fuel cell was developed to simultaneously produce energy and recover ammonium. The applied microbial fuel cell used a gas diffusion cathode. The ammonium transport to the cathode occurred due to migration of ammonium and diffusion of ammonia. In the cathode chamber ionic ammonium was converted to volatile ammonia due to the high pH. Ammonia was recovered from the liquid-gas boundary via volatilization and subsequent absorption into an acid solution. Ammonium recovery and simultaneous energy production from urine was proven possible by this novel approach.
    Design criteria for the plant-microbial fuel cell : electricity generation with living plants : from lab tot application
    Helder, M. - \ 2012
    Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Bert Hamelers; David Strik. - [S.l.] : s.n. - ISBN 9789461733511
    microbiële brandstofcellen - opwekking van elektriciteit - arundo donax - spartina anglica - arundinella - bio-elektrische potentiaal - selectiecriteria - bio-energie - biobased economy - microbial fuel cells - electricity generation - arundo donax - spartina anglica - arundinella - bioelectric potential - selection criteria - bioenergy - biobased economy
    Om de processen die ten grondslag liggen aan de P-MBC (Plant-Microbiële Brandstofcel) en de factoren die zijn vermogen bepalen beter te begrijpen was het doel van dit proefschrift om design criteria voor de PMBC te bepalen. De eerste focus van de design criteria was om het vermogen van de P-MBC te verhogen. Hoe hoger het vermogen, hoe groter de bijdrage aan duurzame elektriciteitsproductie. De ontwikkeling van een nieuwe elektriciteitstechnologie tot een volwaardig commercieel product behelst echter meer dan alleen het vermogen. Daarom hebben we nog een aantal andere factoren onderzocht die de toepassingsmogelijkheden van de P-MBC bepalen.
    Effect of Toxic Components on Microbial Fuel Cell-Polarization Curves and Estimation of the Type of Toxic Inhibition
    Stein, N.E. ; Hamelers, H.V.M. ; Straten, G. van; Keesman, K.J. - \ 2012
    Biosensors 2 (2012)3. - ISSN 2079-6374 - p. 255 - 268.
    Polarization curves are of paramount importance for the detection of toxic components in microbial fuel cell (MFC) based biosensors. In this study, polarization curves were made under non-toxic conditions and under toxic conditions after the addition of various concentrations of nickel, bentazon, sodiumdodecyl sulfate and potassium ferricyanide. The experimental polarization curves show that toxic components have an effect on the electrochemically active bacteria in the cell. (Extended) Butler Volmer Monod (BVM) models were used to describe the polarization curves of the MFC under nontoxic and toxic conditions. It was possible to properly fit the (extended) BVM models using linear regression techniques to the polarization curves and to distinguish between different types of kinetic inhibitions. For each of the toxic components, the value of the kinetic inhibition constant Ki was also estimated from the experimental data. The value of Ki indicates the sensitivity of the sensor for a specific component and thus can be used for the selection of the biosensor for a toxic component.
    Stroom uit de afsluitdijk : energie winnen op de grens tussen zout en zoet
    Hamelers, Bert ; Buisman, Cees ; Baptist, Martin - \ 2012
    fresh water - saline water - energy policy - energy sources - afsluitdijk - lake ijssel - north sea
    On-line detection of toxic components using a microbial fuel cell-based biosensor
    Stein, N.E. ; Hamelers, H.V.M. ; Straten, G. van; Keesman, K.J. - \ 2012
    Journal of Process Control 22 (2012)9. - ISSN 0959-1524 - p. 1755 - 1761.
    Safe drinking water without toxic chemicals is crucial for people's health. A recently developed sensor for the detection of toxic components in water is the microbial fuel cell (MFC)-based biosensor. In this biosensor, substrate consumption rate and metabolic activity of bacteria are directly related to the electric current. A reduction in current under otherwise similar conditions is an indication of toxic inhibition. Under steady state conditions, current can be described by the Butler–Volmer–Monod (BVM) model. Knowing which parameters of this model change under toxic contamination can give an indication on the type of toxicity. The model requires that the substrate concentration is known. It is shown in this paper that is not possible to estimate both the substrate concentration as well as the BVM parameters on-line from current data at constant overpotential. However, it appears that substrate concentration and substrate consumption rate can be estimated on-line, and that after a linear reparametrization the BVM parameters can be estimated by ordinary least-squares techniques from a polarization curve that is generated as soon as a suspect change in current occurs. Analysis shows that a weighted least-squares method is necessary to secure a good fit at the overpotentials where current is most sensitive to changes in kinetic parameters. A protocol for on-line detection of toxicity and for detection of the type of kinetic inhibition is provided.
    Water Desalination with Wires
    Porada, S. ; Sales, B.B. ; Hamelers, H.V.M. ; Biesheuvel, P.M. - \ 2012
    Journal of Physical Chemistry Letters 3 (2012)12. - ISSN 1948-7185 - p. 1613 - 1618.
    membrane capacitive deionization - seawater desalination - salinity difference - carbon electrodes - porous-electrodes - energy - electrolytes - technology - efficiency - storage
    We show the significant potential of water desalination using a novel capacitive wire-based technology in which anode/cathode wire pairs are constructed from coating a thin porous carbon electrode layer on top of electrically conducting rods (or wires). By alternately dipping an array of electrode pairs in freshwater with and in brine without an applied cell voltage, we create an ion adsorption/desorption cycle. We show experimentally how in six subsequent cycles we can reduce the salinity of 20 mM feed (brackish) water by a factor of 3, while application of a cation exchange membrane on the cathode wires makes the desalination factor increase to 4. Theoretical modeling rationalizes the experimental findings, and predicts that system performance can be significantly enhanced by material modifications. To treat large volumes of water, multiple stacks of wire pairs can be used simultaneously in a “merry-go-round” operational mode.
    Electricity generation by living plants in a plant microbial fuel cell
    Timmers, R.A. - \ 2012
    Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Bert Hamelers; David Strik. - S.l. : s.n. - ISBN 9789461912824 - 196
    opwekking van elektriciteit - microbiële brandstofcellen - electricity generation - microbial fuel cells

    Society is facing local and global challenges to secure needs of people. One of those needs is the increasing demand of energy. Currently most energy is generated by conversion of fossil fuels. The major drawback of using fossil fuels is pollution of the environment by emission of carbon dioxide, nitrogen oxides, sulfur dioxide, volatile organic compounds, heavy metals, and fine particles. Furthermore fossil fuels are not renewable in a time scale in the order of decades. The microbial solar cell (MSC) is a new collective name of biotechnological systems that integrate photosynthetic and electrochemically active organisms to generate electricity in a clean and renewable manner. Among the MSCs, the plant microbial fuel cell (PMFC) that employs higher plants, is the most promising MSCs. In PMFCs, plant roots provide substrate for electrochemically active bacteria in the anode by the loss of organic compounds. In natural environments plant roots loose organic compound by diffusion through the cell membrane, or release organic compounds in order to acquire necessary nutrient. In both cases these organic compounds are an energy source for micro-organisms. In the PMFC these lost or released organic compounds are partly utilized by electrochemically active bacteria. During the oxidation of these organic compounds s electrochemically active bacteria transfer electrons to the anode electrode and produce protons and carbon dioxide. The electrons flow via a power harvester to the cathode compartment where the electrons are consumed by typically oxygen reduction. The aim of this thesis was to characterize the PMFC biologically and electrochemically and to improve the design towards higher applicable power outputs. The approach of this thesis was to understand processes in the PMFC which limit electrical power generation and use these findings to improve electrical power generation and the applicability of the PMFC design.

    Characterization of the internal resistance of a plant microbial fuel cell
    Timmers, R.A. ; Strik, D.P.B.T.B. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2012
    Electrochimica Acta 72 (2012). - ISSN 0013-4686 - p. 165 - 171.
    exchange membranes - rice plants - electricity - rhizodeposits - generation - transport - bacteria
    The objective of this research was to clarify the internal resistance of the PMFC. To characterize internal resistances of the PMFC current interrupt and polarization were used, and partial resistances were calculated. The internal resistance consisted mainly of anode resistance and membrane resistance which both decreased during current interrupt. The anode resistance was the result of mass transfer resistance in the electrochemically active biofilm. The membrane resistance was the result of accumulation of cations in the cathode. The polarization showed a distinct hysteresis which was explained by the increase of the internal resistance during polarization. The increase of this resistance makes it difficult to interpret the maximum power output of the PMFC.
    New plant-growth medium for increased power output of the Plant-Microbial Fuel Cell
    Helder, M. ; Strik, D.P.B.T.B. ; Hamelers, H.V.M. ; Kuijken, R.C.P. ; Buisman, C.J.N. - \ 2012
    Bioresource Technology 104 (2012). - ISSN 0960-8524 - p. 417 - 423.
    salt-marsh - denitrification - electricity - spartina - rice - soil
    In a Plant-Microbial Fuel Cell anode-conditions must be created that are favorable for plant growth and electricity production. One of the major aspects in this is the composition of the plant-growth medium. Hoagland medium has been used until now, with added phosphate buffer to reduce potential losses over the membrane because of differences in pH between anode and cathode. We developed a new, improved plant-growth medium that improves current production, while the plant keeps growing. This medium is a nitrate-less, ammonium-rich medium that contains all macro- and micro-nutrients necessary for plant growth, with a balanced amount of bicarbonate buffer. Sulphate presence in the plant-growth medium helps to keep a low anode-potential. With the new plant-growth medium the maximum current production of the Plant-Microbial Fuel Cell increased from 186 mA/m(2) to 469 mA/m(2).
    Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell
    Timmers, R.A. ; Rothballer, M. ; Strik, D.P.B.T.B. ; Engel, M. ; Schulz, M. ; Hartmann, A. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2012
    Applied Microbiology and Biotechnology 94 (2012)2. - ISSN 0175-7598 - p. 537 - 548.
    targeted oligonucleotide probes - iron-reducing bacteria - in-situ hybridization - electricity-generation - fe(iii)-reducing bacterium - shewanella-putrefaciens - activated-sludge - soil bacteria - rice plants - human feces
    The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into the competition for electron donor in a PMFC. This paper characterises the anode-rhizosphere bacterial community of a Glyceria maxima (reed mannagrass) PMFC. Electrochemically active bacteria (EAB) were located on the root surfaces, but they were more abundant colonising the graphite granular electrode. Anaerobic cellulolytic bacteria dominated the area where most of the EAB were found, indicating that the current was probably generated via the hydrolysis of cellulose. Due to the presence of oxygen and nitrate, short-chain fatty acid-utilising denitrifiers were the major competitors for the electron donor. Acetate-utilising methanogens played a minor role in the competition for electron donor, probably due to the availability of graphite granules as electron acceptors.
    Rhizosphere anode model explains high oxygen levels during operation of a Glyceria maxima PMFC
    Timmers, R.A. ; Strik, D.P.B.T.B. ; Arampatzoglou, C. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Bioresource Technology 108 (2012). - ISSN 0960-8524 - p. 60 - 67.
    microbial fuel-cells - triticum-aestivum l - rice plants - electricity production - root exudation - organic-acids - carbon - solubilization - rhizodeposits - turnover
    In this paper, the effect of root oxygen loss on energy recovery of the plant microbial fuel cell (PMFC) is described. In this manner, advanced understanding of competing processes within the rhizosphere-anode interface was provided. A microscopic model was developed on the basis of exudation, oxygen loss, biological oxidation, and biological current generation. The model was successfully validated by comparison to oxygen concentration profiles, volatile fatty acid profiles, and chemical oxygen demand profiles measured in the anode compartment. The model predicted oxic zones around roots in the anode of the plant microbial fuel cell. Results show no direct link between current generation and photosynthesis. This was consistent with the model which predicted that current was generated via hydrolysis of root-derived organic compounds. This result means that to optimize energy recovery of a PMFC, the plant selection should focus on high root biomass production combined with low oxygen loss.
    Microbial electrolysis cells for production of methane from CO2: long-term performance and perspectives
    Eerten-Jansen, M.C.A.A. van; Heijne, A. ter; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    International Journal of Energy Research 36 (2012)6. - ISSN 0363-907X - p. 809 - 819.
    fuel-cells - electricity-generation - exchange membranes - technology - hydrogen - energy - reduction - biofuels - biomass - cation
    A methane-producing microbial electrolysis cell (MEC) is a technology to convert CO2 into methane, using electricity as an energy source and microorganisms as the catalyst. A methane-producing MEC provides the possibility to increase the fuel yield per hectare of land area, when the CO2 produced in biofuel production processes is converted to additional fuel methane. Besides increasing fuel yield per hectare of land area, this also results in more efficient use of land area, water, and nutrients. In this research, the performance of a methane-producing MEC was studied for 188¿days in a flat-plate MEC design. Methane production rate and energy efficiency of the methane-producing MEC were investigated with time to elucidate the main bottlenecks limiting system performance. When using water as the electron donor at the anode during continuous operation, methane production rate was 0.006¿m3/m3 per day at a cathode potential of -0.55¿V vs. normal hydrogen electrode with a coulombic efficiency of 23.1%. External electrical energy input was 73.5¿kWh/m3 methane, resulting in a voltage efficiency of 13.4%. Consequently, overall energy efficiency was 3.1%. The maximum achieved energy efficiency was obtained in a yield test and was 51.3%. Analysis of internal resistance showed that in the short term, cathode and anode losses were dominant, but with time, also pH gradient and transport losses became more important. The results obtained in this study are used to discuss the possible contribution of methane-producing MECs to increase the fuel yield per hectare of land area.
    Acetate enhances startup of a H2-producing microbial biocathode
    Jeremiasse, A.W. ; Hamelers, H.V.M. ; Croese, E. ; Buisman, C.J.N. - \ 2012
    Biotechnology and Bioengineering 109 (2012)3. - ISSN 0006-3592 - p. 657 - 664.
    fuel-cells - geobacter-sulfurreducens - electrolysis cells - performance - methane
    H2 can be produced from organic matter with a microbial electrolysis cell (MEC). To decrease MEC capital costs, a cathode is needed that is made of low-cost material and produces H2 at high rate. A microbial biocathode is a low-cost candidate, but suffers from a long startup and a low H2 production rate. In this study, the effects of cathode potential and carbon source on microbial biocathode startup were investigated. Application of a more negative cathode potential did not decrease the startup time of the biocathode. If acetate instead of bicarbonate was used as carbon source, the biocathode started up more than two times faster. The faster startup was likely caused by a higher biomass yield for acetate than for bicarbonate, which was supported by thermodynamic calculations. To increase the H2 production rate, a flow through biocathode fed with acetate was investigated. This biocathode produced 2.2¿m3¿H2¿m-3¿reactor day-1 at a cathode potential of -0.7¿V versus NHE, which was seven times that of a parallel flow biocathode of a previous study
    Water, Energy and Salt: interrelations and sustainability
    Rijnaarts, H.H.M. ; Post, J.W. ; Wal, A.F. van der; Biesheuvel, P.M. ; Leusbrock, I. ; Hamelers, H.V.M. ; Bruning, H. ; Buisman, C.J.N. - \ 2011
    Effect of operational parameters on Coulombic efficiency in bioelectrochemical systems
    Sleutels, T.H.J.A. ; Darus, L. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2011
    Bioresource Technology 102 (2011)24. - ISSN 0960-8524 - p. 11172 - 11176.
    microbial fuel-cells - electricity-generation - electrolysis cells - hydrogen - acetate - resistance - transport - bacteria - cultures - methane
    To create an efficient bioelectrochemical system, a high Coulombic efficiency is required. This efficiency is a direct measure for the competition between electrogens and methanogens when acetate is used as substrate. In this study the Coulombic efficiency in a microbial electrolysis cell was investigated. As a result of an increase in substrate concentration from 1 to 35 mM, the current density increased to 21.1 A/m(2), while the Coulombic efficiency decreased to 52%. As a result of an increase in anode potential from -450 to -0.250 mV, the current density increased to 20.9 A/m(2), while the Coulombic efficiency increased 21%. Knowledge about the substrate affinity and growth kinetics is crucial to control the Coulombic efficiency. Further research is required to optimize strategies to find a balance between the Coulombic efficiency, current density and removal rate of organic material.
    Pre-desalination with electro-membranes for SWRO
    Post, J.W. ; Huiting, H. ; Cornelissen, E.R. ; Hamelers, H.V.M. - \ 2011
    Desalination and Water Treatment 31 (2011)1-3. - ISSN 1944-3994 - p. 296 - 304.
    reverse-osmosis membranes - electrodialysis - water - salt
    Although seawater reverse osmosis (SWRO) is currently the only non-thermal desalination process in practical use, its characteristics make it difficult to approach the ideal reversible process. SWRO has a low water recovery (determined by the osmotic pressure) and relatively high energy consumption. A breakthrough in development of SWRO membranes can not be expected; at maximum a recovery of 60% could be obtained with membranes that can stand ultra-high pressures. In our project, an alternative development of desalination is introduced in which the osmotic pressure difference is reduced prior to SWRO with the use of electro-membranes, as in electrodialysis (ED). ED has distinctive and complementary assets when compared to SWRO. ED enables an operation close to the reversible limit, at least to the first extent of the desalination process. ED is an ideal pre-desalination step as: (i) the water recovery is not limited by a driving force (e. g., pressure), (ii) the specific energy consumption is directly proportional to the salt removal, (iii) the process economy allows low ionic fluxes and thus low irreversible losses, (iv) the system can be operated with infinitesimal changes in salinity (a pre-requisite for reversibility), and (v) the pre-treatment efforts can be kept limited. In this paper we compare a hybrid ED-SWRO scheme with state-of-the-art desalination schemes with respect to costs and energy consumption.
    Plant-microbial fuel cells: Matching results and model predictions to show the technological and economical perspectives of PlantPower
    Strik, D.P.B.T.B. ; Hamelers, H.V.M. ; Helder, M. ; Timmers, R.A. ; Steinbusch, K.J.J. ; Buisman, C.J.N. - \ 2011
    Plant Microbial Fuel Cells; a new marine energy source
    Strik, D.P.B.T.B. ; Hamelers, H.V.M. ; Helder, M. ; Timmers, R.A. ; Steinbusch, K.J.J. ; Buisman, C.J.N. - \ 2011
    Worldwide there is need for more clean, renewable, sustainable energy. Plant microbial fuel cells (Plant- MFCs) generate in-situ green electricity(Strik, Hamelers et al. 2008). How does this work? By photosynthesis the plant is capturing solar energy which is transformed into chemical energy as organic matter. Easily 20 to 40% of this organic matter is released via the plant roots into the bioanode of the microbial fuel cell. At the anode electrochemically active oxidise the organic matter while using the carbon anode electrode as final electron acceptor. The released electrons flow via energy harvester to the cathode were typically oxygen is reduced. Under Western European weather conditions a power output of 3.2 W/m2 is expected which is up to 10 times higher than conventional biomass electricity systems (Strik, Timmers et al. 2011). At this moment the Plant-MFCs long term power output is 50 mW/m2 which is attractive for powering sensors or LEDs (Timmers, Strik et al. 2010). To achieve more plantpower larger areas are needed. Plants in Plant-MFCs grown under waterlogged conditions to support the preferred conditions in the anode. Therefore it's interesting to integrate Plant-MFCs into salt marsh wetlands as these are widely present. In Western Europe salt marshes, common cord-grass (Spartina anglica) is one of the dominant species (Roberts and Pullin 2008). Spartina anglica is used as one of the model plants in the Plant-MFC. The objective of the presentation is to give an overview of recent results of Spartina anglica Plant-MFCs and show the identified challenges to improve system performance. Lab scale experiments and model work was performed. Discussed will be the value of the technology and challenges to introduce a Plant-MFC into marine ecosystems
    Modelling microbial competition in plant microbial fuel cells
    Strik, D.P.B.T.B. ; Timmers, R.A. ; Helder, M. ; Steinbusch, K.J.J. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2011
    Identifying charge and mass transfer resistances of an oxygen reducing biocathode
    Heijne, A. ter; Schaetzle, O. ; Gimenez, S. ; Fabregat-Santiago, F. ; Bisquert, J. ; Strik, D.P.B.T.B. ; Barrière, F. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2011
    Energy & Environmental Science 4 (2011)12. - ISSN 1754-5692 - p. 5035 - 5043.
    microbial fuel-cells - anode-respiring bacteria - performance - electrodes - biofilm - mechanism - graphite - model
    this study, we identified mass and charge transfer resistances for an oxygen reducing biocathode in a microbial fuel cell (MFC) by electrochemical impedance spectroscopy (EIS). The oxygen reducing biocathode was grown using nitrifying sludge as the inoculum. A standard model for charge transfer at the electrode surface combined with diffusion across a boundary layer was used. EIS measurements were performed under variation of both linear flow velocities and cathode potentials. Fitting the impedance data to the standard model at constant potential and different flow rates confirmed that increasing flow rate had no effect on charge transfer resistance, but led to a decrease in mass transfer resistance. From the variation in cathode potential at constant flow rate, a minimum in charge transfer resistance was found at 0.28 V vs. Ag/AgCl. The minimum in charge transfer resistance could be explained by the combined biochemical and electrochemical kinetics typical for bioelectrochemical systems.
    Performance of a scaled-up Microbial Fuel Cell with iron reduction as the cathode reaction
    Heijne, A. ter; Liu, F. ; Rijnsoever, L.S. van; Saakes, M. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2011
    Journal of Power Sources 196 (2011)18. - ISSN 0378-7753 - p. 7572 - 7577.
    operation - oxidation - systems
    Scale-up studies of Microbial Fuel Cells are required before practical application comes into sight. We studied an MFC with a surface area of 0.5 m2 and a volume of 5 L. Ferric iron (Fe3+) was used as the electron acceptor to improve cathode performance. MFC performance increased in time as a combined result of microbial growth at the bio-anode, increase in iron concentration from 1 g L-1 to 6 g L-1, and increased activity of the iron oxidizers to regenerate ferric iron. Finally, a power density of 2.0 W m-2 (200 W m-3) was obtained. Analysis of internal resistances showed that anode resistance decreased from 109 to 7 mO m2, while cathode resistance decreased from 939 to 85 mO m2. The cathode was the main limiting factor, contributing to 58% of the total internal resistance. Maximum energy efficiency of the MFC was 41%.
    Performance of metal alloys as hydrogen evolution reaction catalysts in a microbial electrolysis cell
    Jeremiasse, A.W. ; Bergsma, J. ; Kleijn, J.M. ; Saakes, M. ; Buisman, C.J.N. ; Cohen Stuart, M.A. ; Hamelers, H.V.M. - \ 2011
    International Journal of Hydrogen Energy 36 (2011)17. - ISSN 0360-3199 - p. 10482 - 10489.
    cobalt-molybdenum electrodeposition - exchange membranes - stainless-steel - cathodes - ph - electrochemistry - transport - tungsten - model - water
    H2 can be produced from organic matter with a microbial electrolysis cell (MEC). To decrease the energy input and increase the H2 production rate of an MEC, a catalyst is used at the cathode. Platinum is an effective catalyst, but its high costs stimulate searching for alternatives, such as non-noble metal alloys. This study demonstrates that copper sheet coated with nickel-molybdenum, nickel-iron-molybdenum or cobalt-molybdenum alloys have a higher catalytic activity for the hydrogen evolution reaction than nickel cathodes, measured near neutral pH. However, the catalytic activity cannot be fully exploited near neutral pH because of mass transport limitation. The catalytic activity is best exploited at alkaline pH where mass transport is not limiting. This was demonstrated in an MEC with a cobalt-molybdenum coated cathode and anion exchange membrane, which produced 50 m3 H2 m-3 MEC d-1 (at standard temperature and pressure) at an electricity input of 2.5 kWh m-3 H2.
    Kinetic models for detection of toxicity in a microbial fuel cell based biosensor
    Stein, N.E. ; Keesman, K.J. ; Hamelers, H.V.M. ; Straten, G. van - \ 2011
    Biosensors and Bioelectronics 26 (2011)7. - ISSN 0956-5663 - p. 3115 - 3120.
    biofilm anode - bacteria - system
    Currently available models describing microbial fuel cell (MFC) polarization curves, do not describe the effect of the presence of toxic components. A bioelectrochemical model combined with enzyme inhibition kinetics, that describes the polarization curve of an MFC-based biosensor, was modified to describe four types of toxicity. To get a stable and sensitive sensor, the overpotential has to be controlled. Simulations with the four modified models were performed to predict the overpotential that gives the most sensitive sensor. These simulations were based on data and parameter values from experimental results under non-toxic conditions. Given the parameter values from experimental results, controlling the overpotential at 250 mV leads to a sensor that is most sensitive to components that influence the whole bacterial metabolism or that influence the substrate affinity constant (Km). Controlling the overpotential at 105 mV is the most sensitive setting for components influencing the ratio of biochemical over electrochemical reaction rate constants (K1), while an overpotential of 76 mV gives the most sensitive setting for components that influence the ratio of the forward over backward biochemical rate constants (K2). The sensitivity of the biosensor was also analyzed for robustness against changes in the model parameters other than toxicity. As an example, the tradeoff between sensitivity and robustness for the model describing changes on K1 (IK1) is presented. The biosensor is sensitive for toxic components and robust for changes in model parameter K2 when overpotential is controlled between 118 and 140 mV under the simulated conditions.
    Cathode innovations for enhanced H2 production through microbial electrolysis
    Jeremiasse, A.W. - \ 2011
    Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Bert Hamelers; Mieke Kleijn. - [S.l.] : S.n. - ISBN 9789085859895 - 168
    elektrolyse - microbiële activiteiten - bio-energie - biomassa - waterstof - biobased economy - electrolysis - microbial activities - bioenergy - biomass - hydrogen - biobased economy
    Met een microbiële elektrolysecel (MEC) kan waterstof worden gewonnen uit organische reststromen. Aan de bioanode van een MEC zetten elektrochemisch actieve bacteriën organisch materiaal om in stroom, welke vervolgens aan de kathode wordt omgezet in waterstof. Dit proces behoeft een aangelegd voltage van zo’n 0.4 tot 1.0 V. Dit proces combineert dus de omzetting van reststromen met de productie van een waardevol product; waterstof. Binnen dit onderzoek is gekeken naar goedkope alternatieven voor de platinakathode. Door gebruik te maken van, voor dit proces, innovatieve kathoden zoals kathoden gebaseerd op niet-edele metalen blijkt het mogelijk om de waterstofproductie aanmerkelijk te verhogen en tegelijkertijd de MEC kosten te verlagen. Daarmee is een grote stap gezet richting de ontwikkeling van een rendabele MEC.
    Microbial Communities and Electrochemical Performance of Titanium-Based Anodic Electrodes in a Microbial Fuel Cell
    Michaelidou, U. ; Heijne, A. ter; Euverink, G.J.W. ; Hamelers, H.V.M. ; Stams, A.J.M. ; Geelhoed, J.S. - \ 2011
    Applied and Environmental Microbiology 77 (2011)3. - ISSN 0099-2240 - p. 1069 - 1075.
    gradient gel-electrophoresis - waste-water treatment - geobacter-sulfurreducens - electricity-generation - bacterial communities - graphite-electrodes - ribosomal-rna - oxidation - technology - bioenergy
    Four types of titanium (Ti)-based electrodes were tested in the same microbial fuel cell (MFC) anodic compartment. Their electrochemical performances and the dominant microbial communities of the electrode biofilms were compared. The electrodes were identical in shape, macroscopic surface area, and core material but differed in either surface coating (Pt- or Ta-coated metal composites) or surface texture (smooth or rough). The MFC was inoculated with electrochemically active, neutrophilic microorganisms that had been enriched in the anodic compartments of acetate-fed MFCs over a period of 4 years. The original inoculum consisted of bioreactor sludge samples amended with Geobacter sulfurreducens strain PCA. Overall, the Pt- and Ta-coated Ti bioanodes (electrode-biofilm association) showed higher current production than the uncoated Ti bioanodes. Analyses of extracted DNA of the anodic liquid and the Pt- and Ta-coated Ti electrode biofilms indicated differences in the dominant bacterial communities. Biofilm formation on the uncoated electrodes was poor and insufficient for further analyses. Bioanode samples from the Pt- and Ta-coated Ti electrodes incubated with Fe(III) and acetate showed several Fe(III)-reducing bacteria, of which selected species were dominant, on the surface of the electrodes. In contrast, nitrate-enriched samples showed less diversity, and the enriched strains were not dominant on the electrode surface. Isolated Fe(III)-reducing strains were phylogenetically related, but not all identical, to Geobacter sulfurreducens strain PCA. Other bacterial species were also detected in the system, such as a Propionicimonas-related species that was dominant in the anodic liquid and Pseudomonas-, Clostridium-, Desulfovibrio-, Azospira-, and Aeromonas-related species
    Effects of ammonium concentration and charge exchange on ammonium recovery from high strength wastewater using a microbial fuel cell
    Kuntke, P. ; Geleij, M. ; Bruning, H. ; Zeeman, G. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2011
    Bioresource Technology 102 (2011)6. - ISSN 0960-8524 - p. 4376 - 4382.
    ion-transport - performance - ph - electrolysis - membrane - toxicity
    Ammonium recovery using a 2 chamber microbial fuel cell (MFC) was investigated at high ammonium concentration. Increasing the ammonium concentration (from 0.07 g to 4 g ammonium-nitrogen/L) by addition of ammonium chloride did not affect the performance of the MFC. The obtained current densities by DC-voltammetry were higher than 6 A/m2 for both operated MFCs. Also continuous operation at lower external resistance (250O) showed an increased current density (0.9 A/m2). Effective ammonium recovery can be achieved by migrational ion flux through the cation exchange membrane to the cathode chamber, driven by the electron production from degradation of organic substrate. The charge transport was proportional to the concentration of ions. Nonetheless, a concentration gradient will influence the charge transport. Furthermore, a charge exchange process can influence the charge transport and therefore the recovery of specific ions.
    Biological formation of caproate and caprylate from acetate: fuel and chemical production from low grade biomass
    Steinbusch, K.J.J. ; Hamelers, H.V.M. ; Plugge, C.M. ; Buisman, C.J.N. - \ 2011
    Energy & Environmental Science 4 (2011)1. - ISSN 1754-5692 - p. 216 - 224.
    fermentative hydrogen-production - fatty-acids - clostridium-kluyveri - carboxylic-acids - mixed cultures - bacteria - ethanol - 2-bromoethanesulfonate - methanogenesis - ketonization
    This research introduces an alternative mixed culture fermentation technology for anaerobic digestion to recover valuable products from low grade biomass. In this mixed culture fermentation, organic waste streams are converted to caproate and caprylate as precursors for biodiesel or chemicals. It was found that acetate, as the main intermediate of anaerobic digestion, can be elongated to medium chain fatty acids with six and eight carbon atoms. Mixed microbial communities were able to produce 8.17 g l-1 caproate and 0.32 g l-1 caprylate under methanogenesis-suppressed conditions in a stable batch reactor run. The highest production rate was 25.6 mM C caproate per day with a product yield of 0.6 mol C per mol C. This elongation process occurred with both ethanol and hydrogen as electron donors, demonstrating the flexibility of the process. Microbial characterization revealed that the microbial populations were stable and dominated by relatives of Clostridium kluyveri
    Microbial solar cells: applying photosynthetic and electrochemically active organisms
    Strik, D.P.B.T.B. ; Timmers, R.A. ; Helder, M. ; Steinbusch, K.J.J. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2011
    Trends in Biotechnology 29 (2011)1. - ISSN 0167-7799 - p. 41 - 49.
    fuel-cells - electricity production - bioelectrochemical systems - energy performance - green electricity - biogas production - oxygen reduction - ion-transport - waste-water - rice plants
    Microbial solar cells (MSCs) are recently developed technologies that utilize solar energy to produce electricity or chemicals. MSCs use photoautotrophic microorganisms or higher plants to harvest solar energy, and use electrochemically active microorganisms in the bioelectrochemical system to generate electrical current. Here, we review the principles and performance of various MSCs in an effort to identify the most promising systems, as well as the bottlenecks and potential solutions, for “real-life” MSC applications. We present an outlook on future applications based on the intrinsic advantages of MSCs, specifically highlighting how these living energy systems can facilitate the development of an electricity-producing green roof.
    Butler–Volmer–Monod model for describing bio-anode polarization curves
    Hamelers, H.V.M. ; Heijne, A. ter; Stein, N. ; Rozendal, R.A. ; Buisman, C.J.N. - \ 2011
    Bioresource Technology 102 (2011)1. - ISSN 0960-8524 - p. 381 - 387.
    microbial fuel-cells - respiring bacteria - electron-transfer - biofilm anode - performance - proteins
    A kinetic model of the bio-anode was developed based on a simple representation of the underlying biochemical conversions as described by enzyme kinetics, and electron transfer reactions as described by the Butler–Volmer electron transfer kinetics. This Butler–Volmer–Monod model was well able to describe the measured bio-anode polarization curves. The Butler–Volmer–Monod model was compared to the Nernst–Monod model described the experimental data significantly better. The Butler–Volmer–Monod model has the Nernst–Monod model as its full electrochemically reversible limit. Contrary to the Nernst–Monod model, the Butler–Volmer–Monod model predicts zero current at equilibrium potential. Besides, the Butler–Volmer–Monod model predicts that the apparent Monod constant is dependent on anode potential, which was supported by experimental results.
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