Korneel Rabaey

https://doi. org/10.1016/j. ese. 2023.100336 2666-4984/© 2023 Published by Elsevier BV on behalf of Chinese Society for Environmental Sciences, Harbin Institute of Technology, Chinese Research Academy of Environmental Sciences. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/).

The mechanisms and by-product formation of electrochemical oxidation (EO) for As(III) oxidation in drinking water treatment using groundwater was investigated. Experiments were carried out using a flowthrough system, with an RuO2/IrO2 MMO Ti anode electrode, fed with synthetic and natural groundwater containing As(III) concentrations in a range of around 75 and 2 µg/L, respectively. Oxidation was dependent on charge dosage (CD) [C/L] and current density [A/m2], with the latter showing plateau behaviour for increasing intensity. As(III) concentrations of <0.3 µg/L were obtained, indicating oxidation of 99.9 % of influent As(III). Achieving this required a higher charge dosage for the natural groundwater (>40 C/L) compared to the oxidation in the synthetic water matrix (20 C/L), indicating reaction with natural organic matter or other compounds. As(III) oxidation in groundwater required an energy consumption of 0 …

A number of existing and emerging technologies can recover nitrogen from urine. A preliminary step in many nitrogen recovery processes is hydrolyzing urea to ammonium, a biologically-mediated process that can take days to weeks without intervention. The ability to achieve urea hydrolysis quickly and reliably would increase the feasibility of decentralized nitrogen recovery, especially where space and treatment time are constrained. The goal of this research was to determine whether urea hydrolysis could be accelerated by providing an inoculum containing microorganisms likely to have urease activity (feces or soil), providing a carrier to support attached growth (plastic carriers, granular activated carbon, or no carrier), and modifying the hydraulic retention time (HRT; 1.3, 2, and 4 days) and feeding frequency (Δt = 4, 24 h). Inoculated reactors achieved significantly more urea hydrolysis, and reactors …

Periodic polarization can improve the performance of anodic electroactive biofilms (EABs). The impact of the half-period duration was previously investigated at constant duty cycle (50%), i.e., the proportion of a period during which the electrode is polarized. Here, we cultured eight EABs on glassy carbon electrodes at four different duty cycles (50%, 67%, 80% and 91%) by varying the time interval under open circuit conditions, while keeping the polarization duration at 10 s. The shorter duty cycles slightly slowed initial growth but produced EABs generating higher faradaic currents. The total charge recovery over 38 days increased with decreasing duty cycles from 0.53 kC.cm−2 (duty cycle of 91%) to 1.65 kC.cm−2 (50%). EABs with the shortest duty cycle fully detached twice from the electrode surface, but detachments were quickly followed by the formation of more efficient EABs. We then carried out controlled …

Low electrode potentials increase conductivity and current production of Geobacter sulfurreducens biofilms. Universiteit Gent Add publications and datasets Lists Sign in Academic Bibliography Search 200 years of publications by Ghent University researchers. Search publications and datasets Advanced search 1 file | 321.04 KB Download Download "(...).pdf" See all downloads Add to list 1.Search results 2.Low electrode potentials increase con... Low electrode potentials increase conductivity and current production of Geobacter sulfurreducens biofilms. Antonin Prévoteau (UGent) , David Hernandez Villamor (UGent) , Korneel Rabaey (UGent) , Tom Van de Wiele (UGent) , Peishuo Li, Musa Aydogan and Marian Verhelst (2023) EU-ISMET, International Society for Microbial Electrochemistry and Technology, 6th European Meeting, Abstracts. Author Antonin Prévoteau (UGent) , David Hernandez Villamor (UGent) , …

In contrast to traditional agriculture, microbial protein (MP) production is highly efficient in nitrogen (N) usage and can be employed to valorize a variety of recovered resources, thereby increasing the overall sustainability of food production. The present study aimed to establish the potential of seven recovered N sources originating from different waste streams for MP production using ethanol and acetate as growth substrates. The evaluation was based on specific growth rate, biomass yield, nutritional quality (i.e. macromolecular composition, amino acid (AA) and lipid profile) and food safety (i.e. concentration of heavy metals, polyaromatic hydrocarbons (PAH), pesticides and antibiotics) of the MP. The majority of the recovered N sources did not affect the kinetics and had a minor impact on the biomass yield, compared to their commercial equivalents. The nutritional content of the biomass was similar to soy flour and …

Sustainable water management is essential to guaranteeing access to safe water and addressing the challenges posed by climate change, urbanization, and population growth. In a typical household, greywater, which includes everything but toilet waste, constitutes 50–80% of daily wastewater generation and is characterized by low organic strength and high volume. This can be an issue for large urban wastewater treatment plants designed for high-strength operations. Segregation of greywater at the source for decentralized wastewater treatment is therefore necessary for its proper management using separate treatment strategies. Greywater reuse may thus lead to increased resilience and adaptability of local water systems, reduction in transport costs, and achievement of fit-for-purpose reuse. After covering greywater characteristics, we present an overview of existing and upcoming technologies for greywater …

A novel electrochemical membrane bioreactor (EMB) integrating succinic acid (SA) production and in situ separation in the anode compartment through an anion exchange membrane was employed in fed-batch fermentations with Y. lipolytica PSA02004 using hydrolysates from the organic fraction of municipal solid waste (OFMSW) as feedstock. The initiation of electrolysis cell operation and the reduction of pH from 6 to 5.5 at 30 h in a 6.7 L bioreactor improved the SA production efficiency, resulting in 66.7 gSA/L, 0.51 g/g yield, 0.78 g/(L·h) productivity, high coulombic efficiency (66.2%) and relatively low electricity consumption for SA separation (2.6 kWh/kgSA). The recirculation of the fermentation broth in the cathode compartment and the OH– produced by water reduction reduced NaOH consumption (35.4%) for pH control during fermentation. The fermentation was efficiently replicated in a 30 L bioreactor with a …

Microbial electrosynthesis (MES) enables the bioproduction of multicarbon compounds from CO2 using electricity as the driver. Although high salinity can improve the energetic performance of bioelectrochemical systems, acetogenic processes under elevated salinity are poorly known. Here MES under 35–60 g L−1 salinity was evaluated. Acetate production in two-chamber MES systems at 35 g L−1 salinity (seawater composition) gradually decreased within 60 days, both under −1.2 V cathode potential (vs. Ag/AgCl) and −1.56 A m−2 reductive current. Carbonate precipitation on cathodes (mostly CaCO3) likely declined the production through inhibiting CO2 supply, the direct electrode contact for acetogens and H2 production. Upon decreasing Ca2+ and Mg2+ levels in three-chamber reactors, acetate was stably produced over 137 days along with a low cathode apparent resistance at 1.9 ± 0.6 mΩ m2 and an …

BackgroundIt is increasingly recognized that conventional food production systems are not able to meet the globally increasing protein needs, resulting in overexploitation and depletion of resources, and environmental degradation. In this context, microbial biomass has emerged as a promising sustainable protein alternative. Nevertheless, often no consideration is given on the fact that the cultivation conditions affect the composition of microbial cells, and hence their quality and nutritional value. Apart from the properties and nutritional quality of the produced microbial food (ingredient), this can also impact its sustainability. To qualitatively assess these aspects, here, we investigated the link between substrate availability, growth rate, cell composition and size of Cupriavidus necator and Komagataella phaffii.ResultsBiomass with decreased nucleic acid and increased protein content was produced at low growth rates …

Electrochemical treatments in (waste)water management show high potential in the global water resource crisis, but are often limited by the ion-exchange membrane (IEM) performance. Low chemical resistance and fouling are major issues in the development of next-generation IEMs. Sulfonated silica-based nanofiber cation-exchange membranes (CEMs) offer a promising solution to these issues due to their superior chemical resistance and self-cleaning properties. Via the direct electrospinning of a sol–gel solution starting from tetraethyl orthosilicate (TEOS) and 3-mercaptopropyl triethoxysilane (MPTES), nanofiber membranes with an ion-exchange capacity (IEC) of 1.3 mmol g−1 can be produced without the need of an additional matrix. The produced nanofiber CEM performs excellent in lab-scale electrochemical tests, with a resistance of 3.2 ± 0.4 *10-3 Ω m2 and a Coulombic efficiency of ± 70 % for the …

Currently, almost all microbial electrosynthesis (MES) reactors were biofilm-driven whether the cathode electron transfer was direct or indirect. It has been proven that cathode biofilm formation is time-consuming, and the current density achieved on these biofilms was relatively low. However, the main challenge for the non-biofilm-driven MES is how to maintain a good Columbic efficiency (CE) at high current densities. Here, we report a novel electro-H2 bubble column reactor with an external hollow fiber membrane gas–liquid contactor to tackle the challenge. The electrolyzer was placed at the bottom of the reactor to produce H2 micro-bubbles (mean diameter 169 ± 7 µm) at a current density of 156 A/m2. The bubble column was put on the top of the cathodic chamber of the electrolyzer to extend the H2 retention time, while the hollow fiber membrane gas–liquid contactor in the external loop was used to recover the …

Corrigendum to "Methylotrophs: from C1 compounds to food" [Curr Opin Biotechnol 75 (2022) 102685] Corrigendum to "Methylotrophs: from C1 compounds to food" [Curr Opin Biotechnol 75 (2022) 102685] Curr Opin Biotechnol. 2023 Jun 9;82:102964. doi: 10.1016/j.copbio.2023.102964. Online ahead of print. Authors Myrsini Sakarika 1 , Ramon Ganigué 1 , Korneel Rabaey 2 Affiliations 1 Center for Microbial Ecology and Technology (CMET), Faculty of Bioscience Engineering Ghent University, Coupure Links 653, 9000 Gent, Belgium; Center for Advanced Process Technology for Urban Resource recovery (CAPTURE), Frieda Saeysstraat, 9052 Gent, Belgium. 2 Center for Microbial Ecology and Technology (CMET), Faculty of Bioscience Engineering Ghent University, Coupure Links 653, 9000 Gent, Belgium; Center for Advanced Process Technology for Urban Resource recovery (CAPTURE), Frieda Saeysstraat, …

Nitrogen is the most crucial element in the production of nutritious feeds and foods. The production of reactive nitrogen by means of fossil fuel has thus far been able to guarantee the protein supply for the world population. Yet, the production and massive use of fertilizer nitrogen constitute a major threat in terms of environmental health and sustainability. It is crucial to promote consumer acceptance and awareness towards proteins produced by highly effective microorganisms, and their potential to replace proteins obtained with poor nitrogen efficiencies from plants and animals. The fact that reactive fertilizer nitrogen, produced by the Haber Bosch process, consumes a significant amount of fossil fuel worldwide is of concern. Moreover, recently, the prices of fossil fuels have increased the cost of reactive nitrogen by a factor of 3 to 5 times, while international policies are fostering the transition towards a more …

A stimulation circuitry for a multichannel potentiostat has individually controllable stimulation channels, and includes at least one circuit group. The circuit group includes:(i) a controllable current source;(ii) a transient suppression module having an input resistively coupled to an output of the current source, the transient suppression module being a module for controllably suppressing a transient current with respect to an output of said transient suppression module;(iii) a demultiplexer having an input resistively coupled to the output of the transient suppression module; and (iv) a controller for selecting an output of the demultiplexer and for operating the transient suppression module with respect to said output selection.

Medium chain carboxylic acids (MCCA) such as caproic acid have a plethora of applications, ranging from food additives to bioplastics. MCCA can be produced via microbial chain elongation using waste and side-streams as substrates, a process that can be more sustainable than conventional production routes. Most chain elongation studies have focused on mesophilic conditions, with only two recent studies hinting at the possibility of thermophilic chain elongation, but a systematic study of its mechanisms is lacking. Here, we investigated thermophilic chain elongation from grass juice, to understand the effect of key operational parameters (pH, temperature, substrate) on the process performance and to establish the key microbial genera and their role in the system. The genus Caproiciproducens was identified as responsible for thermophilic chain elongation, and caproic acid production was most favorable at pH …

Volume 88, no. 22, e01188-22, 2022, https://doi. org/10.1128/aem. 01188-22. Page 5: The “Preliminary techno-economic evaluation” section should read as follows.“MP production from C. saturnus and W. anomalus grown at a balanced initial C/N ratio of 20 shows the best economic outlook for biomass production among all tested conditions (Fig. 6A), with estimated production costs of 4,141 and 4,241 EUR/ton biomass, respectively. M. pulcherrima, C. glutamicum, and M. extorquens should instead be grown with an initial C/N ratio of 5 to reach production costs of 7,173, 13,073, and 15,382 EUR/ton biomass, respectively. When protein, and not biomass, is taken as a reference for the cost comparison, the preferable C/N ratios and microbial species change. C. glutamicum at a C/N ratio of 5 and M. pulcherrima at a C/N ratio of 20 represent the cheapest protein production routes (20,790 and 21,552 EUR/ton protein …

The potential of renewable energy application via direct electrode interaction for the production of bio-based chemicals is a promising technology. The utilization of extracellular energy in pure culture fermentations aims in intracellular redox balance regulation in order to improve fermentation efficiency. This work evaluates the impact of a bioelectrochemical system in succinic acid fermentation and the metabolic response of Actinobacillus succinogenes. The metabolic pathway regulation of A. succinogenes was evaluated via RNA expression of the key enzymes that participate in TCA cycle, pyruvate metabolism and oxidative phosphorylation. The genes that were significantly overexpressed in BES compared to non-BES were phosphoenolpyruvate carboxykinase (0.4-fold change), inorganic pyrophosphatase (2.3-fold change) and hydrogenase (2.2-fold change) and the genes that were significantly …

Granular biofilms producing medium-chain carboxylic acids (MCCA) from carbohydrate-rich industrial feedstocks harbor highly streamlined communities converting sugars to MCCA either directly or via lactic acid as intermediate. We investigated the spatial organization and growth activity patterns of MCCA producing granular biofilms grown on an industrial side stream to test (i) whether key functional guilds (lactic acid producing Olsenella and MCCA producing Oscillospiraceae) stratified in the biofilm based on substrate usage, and (ii) whether spatial patterns of growth activity shaped the unique, lenticular morphology of these biofilms. First, three novel isolates (one Olsenella and two Oscillospiraceae species) representing over half of the granular biofilm community were obtained and used to develop FISH probes, revealing that key functional guilds were not stratified. Instead, the outer 150–500 µm of the …

BackgroundElevated CO2 partial pressure (pCO2) has been proposed as a potential steering parameter for selective carboxylate production in mixed culture fermentation. It is anticipated that intermediate product spectrum and production rates, as well as changes in the microbial community, are (in)directly influenced by elevated pCO2. However, it remains unclear how pCO2 interacts with other operational conditions, namely substrate specificity, substrate-to-biomass (S/X) ratio and the presence of an additional electron donor, and what effect pCO2 has on the exact composition of fermentation products. Here, we investigated possible steering effects of elevated pCO2 combined with (1) mixed substrate (glycerol/glucose) provision; (2) subsequent increments in substrate concentration to increase the S/X ratio; and (3) formate as an additional electron donor.ResultsMetabolite predominance, e.g., propionate vs …