New applications and performance of bioelectrochemical systems

Bioelectrochemical systems (BESs) are emerging technologies which use microorganisms to catalyze the reactions at the anode and/or cathode. BES research is advancing rapidly, and a whole range of applications using different electron donors and acceptors has already been developed. In this mini review, we focus on technological aspects of the expanding application of BESs. We will analyze the anode and cathode half-reactions in terms of their standard and actual potential and report the overpotentials of these half-reactions by comparing the reported potentials with their theoretical potentials. When combining anodes with cathodes in a BES, new bottlenecks and opportunities arise. For application of BESs, it is crucial to lower the internal energy losses and increase productivity at the same time. Membranes are a crucial element to obtain high efficiencies and pure products but increase the internal resistance of BESs. The comparison between production of fuels and chemicals in BESs and in present production processes should gain more attention in future BES research. By making this comparison, it will become clear if the scope of BESs can and should be further developed into the field of biorefineries

Electron storage in electroactive biofilms

Microbial electrochemical technologies (METs) are promising for sustainable applications. Recently, electron storage during intermittent operation of electroactive biofilms (EABs) has been shown to play an important role in power output and electron efficiencies. Insights into electron storage mechanisms, and the conditions under which these occur, are essential to improve microbial electrochemical conversions and to optimize biotechnological processes. Here, we discuss the two main mechanisms for electron storage in EABs: storage in the form of reduced redox active components in the electron transport chain and in the form of polymers. We review electron storage in EABs and in other microorganisms and will discuss how the mechanisms of electron storage can be influenced.This work is part of the research program Vidi (with project number 17516), which is (partly) financed by the Dutch Research Council (NWO). The research was performed in cooperation with Wetsus, the European Centre of Excellence for Sustainable Water Technology. Wetsus is cofunded by the Dutch Ministry of Economic Affairs and Ministry of Infrastructure and Environment, the European Union Regional Development Fund, the Province of Fryslân, and the Northern Netherlands Provinces. The authors would like to thank the participants of the research theme ‘Resource Recovery’ for the fruitful discussions and their financial support. The authors also acknowledge the financial support given by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 – Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Energizing The Life Sciences at WUR

This document presents the state of the art of energy research and education at Wageningen University & Research and outlines our ambitions to contribute to the energy transition. The working paper was written by the WUR Energy Alliance – a recently established network of researchers from all Science Groups at Wageningen University & Research. The WUR Energy Alliance currently consists of 50+ researchers with proven track record and genuine interest in excellent research and education on energy-related issues within the broader WUR domain. The material is derived from the study of WUR energy research projects and a series of meetings with Wageningen University & Research staff

Carbon nanomaterials for electrode modification in CH4-producing bioelectrochemical systems

Introduction: Unprecedented environmental phenomena have led to emerging and challenging plans to tackle global threats for the humanity namely intensive use of fossil resources and global warming. CO2 emission to the atmosphere is one of the major driver of global climate change. In this context, the development of alternative technologies for carbon capture and utilization has attracting more and more attention. Electrochemically assisted CO2 conversion in bioelectrochemical systems (BESs) for CH4 production is a new and emerging technology. This innovative approach allows the storage of electrical renewable energy in the form of CH4 that can, when needed, be reconverted, but also the simultaneous CO2 capture contributing to mitigate the climate change and the global warming. However, this technology has limitations mainly related to the electrons transference between the electrode and the biocatalysts. Previous results, obtained within the research group, demonstrated that it is possible to increase the efficiency of the process by improving the electrode surface area which, in turn, improved the microbial attachment. Methodology: This work aimed to investigate the effect of the presence of carbon nanomaterials (carbon nanotubes (CNTs)) at the cathode, on the CH4 production via CO2 reduction. It was hypothesized that the presence of carbon nanomaterials will improve the electrode surface area, thus increasing the electron transfer between the electrode and the biocatalysts. The production of CH4 was analyzed in two BESs, one working with a modified electrode (BES-CNT) and another one that works as a control with a non-modified electrode (BES-CTRL). The potential of CNTs to improve CH4 production was investigated under different electrochemical control modes, potentiostatic and galvanostatic. In addition, the microbial community developed at the biocathode was also investigated. Results: The results demonstrated that for both electrochemical control modes, the production of CH4 was higher in the presence of CNTs compared to the control assay. The study of the microbial community developed at the biocathode under galvanostatic control demonstrated a clear enrichment of methanogens compared to the initial inoculum, however no significant differences were observed between both BES. Conclusions: In conclusion, this work contributed with preliminary insights on the effect of carbon nanomaterials, namely CNTs, to improve the biocathode performance on BESs for CH4 production from CO2.This study was supported by the Portuguese Foundation for Science and Technology(FCT) under the scope of the strategic funding of UIDB/04469/2020 unit.info:eu-repo/semantics/publishedVersio

Microbial acclimation to concentrated human urine in Bio-electrochemical system

The aim of this study is to promote the gradual acclimation of bioelectroactive microorganisms in BES to concentrated human urine, and to assess different anode potentials and carbon materials in Microbial Electrolysis Cells (MEC). Human urine is highly concentrated in nutrients, representing more than 80% of the total N load and around 45% of the total P load in municipal wastewater. Separation of urine from other wastewater streams is an interesting option to keep these valuable nutrients concentrated, in order to develop a suitable nutrient recovery concept. This work is integrated in the Value from Urine (VFU) concept, where phosphate is recovered from source segregated human urine through struvite precipitation and ammonia is recovered in a Bio-electrochemical System (BES). Enrichment of an anaerobic sludge community in urine-degrading-electroactive microorganisms was promoted in an Microbial Fuel Cell (MFC) operated with increasing concentrations of real human urine (after phosphorous removal, as struvite). This acclimated electroactive biofilm was used to inoculate the anode of MECs, aiming at H2 and ammonia production in the cathode compartment. Different carbon modified anodes and defined anode potentials were assessed in terms of performance and microbial diversity of the developed electroactive biofilms

Bioelectrochemically-assisted recovery of valuable resources from urine

Book of Abstracts of CEB Annual Meeting 2017[Excerpt] Source separated urine is highly concentrated in nutrients and biodegradable compounds. This work explores the potential of combining nutrient recovery from urine with simultaneous energy production in bioelectrochemical systems (BES), under the FP7 project "ValueFromUrine". Non-spontaneous phosphorus (P) recovery by struvite precipitation was analysed by adding three different magnesium (Mg) sources (magnesium chloride (MgCl2), magnesium hydroxide (Mg(OH)2) and magnesium oxide (MgO)). A statistical design of experiments was used to evaluate the effect of Mg:P molar ratio (1:1, 1.5:1 and 2:1) combined with stirring speed (30, 45 and 60 rpm) for each Mg source tested. MgO at 2:1 molar ratio and a stirring speed of 30 rpm allowed to achieve the highest P recovery efficiency (99 %) with struvite crystals size of 50 to 100 μm [1]. Urine obtained after P recovery, showed high concentration of biodegradable compounds being subsequently fed as substrate in a microbial fuel cell (MFC). Microbial acclimation to urine was performed in a MFC resulting in an anaerobic community successfully enriched in “urine-degrading” electroactive microorganisms. When compared to the control assay operated without preliminary microbial enrichment (81±9 mA m-2), the acclimation method achieved significantly higher current density (455 mA m-2) (p<0.05). Tissierella and Paenibacillus were the dominant genus identified in the adapted microbial community. Tissierella can convert creatinine to acetate, whereas bacterial species belonging to the Paenibacillus genus are known to function as exoelectrogens. Corynebacterium that comprise urea-hydrolysing bacteria was also detected in the developed biofilms. [...]info:eu-repo/semantics/publishedVersio

An innovative bioelectrochemical system for the recovery of phosphorus, ammonia and electricity from urine

Ammonium and phosphate fertilizers are needed in agriculture to ensure a sufficient food production. The recovery of valuable nutrients (ammonium and phosphate) from waste(water) streams will help to overcome future shortages and reduce the need for phosphorous ore imports and energy intensive ammonia production. One person produces on average 1.5 L of urine per day, which contains about 9.1 g N /L and 1 g P /L. Urine contributes about 80% of the N load and 50% of the P load in conventional domestic wastewaters. These high nutrient concentrations in urine make it possible to develop more effective and energy efficient recovery technologies. In the ValueFromUrine project the phosphorus recovery will be performed by struvite precipitation from hydrolyzed urine and the resulting effluent will be used for ammonium recovery and simultaneously electricity generation in Bioelectrochemical systems. Bioelectrochemical systems (ie Microbial Fuel Cells) are engineered systems in which bacteria catalyze the oxidation of organic substrates and transfer electrons to anode and at the cathode oxygen is reduced. The aim of our project is to develop, demonstrate and evaluate an effective energy-efficient system for the recovery of nutrients from urine. Our treatment system will be able to recover >95% of the phosphorous (as struvite) and nitrogen (as struvite and ammonia / ammonium sulphate) while producing energy. These products can substitute salts used by the chemical industry, the artificial fertilizer industry and the agricultural sector which are currently obtained in a non-renewable and unsustainable wa

Effect of process conditions on the performance of a dual-reactor biodesulfurization process

The biotechnological gas desulfurization process under haloalkaline conditions is widely applied for removal of toxic H2S from sour gas streams. In this process H2S is biologically oxidized into elemental sulfur. Recently, the process has been extended with an anaerobic process step (dual-reactor line-up), increasing the selectivity for elemental sulfur (S8) from ~85–97% and decreasing the formation of (thio)sulfate. It was also found that biological sulfide uptake took place in the anaerobic bioreactor. In order to apply this process in industry, more insight is needed of the effect of the process conditions on the process performance. The effect of the process conditions HRT and sulfide concentration in the anaerobic bioreactor and pH on the overall product selectivities and on biological sulfide uptake in the anaerobic bioreactor were investigated. 7 experiments were performed in a pilot-scale biodesulfurization set-up. In all experiments, high selectivities (>95%) for S8 formation were obtained, except when the pH in the aerated bioreactor was increased from 8.5 to 9.1 (selectivity of 88%). Furthermore, biological sulfide uptake in the anaerobic bioreactor increased at higher sulfide concentrations and at higher pH. We hypothesize the biological sulfide uptake under anaerobic conditions is related to polysulfide formation. Our results increase the understanding how to control biological sulfide conversion in the dual-reactor biodesulfurization process