Understanding nitrogen recovery from wastewater with a high nitrogen concentration using microbial electrolysis cells

9 p.This study was aimed at understanding the effect of applied voltage, catholyte and reactor scale on nitrogen recovery from two different organic wastes (digestate and pig slurry) by means of microbial electrolysis cell (MEC) technology. For this purpose, MEC sizes of 100, 500 and 1000 mL were tested at applied voltages of 0.6, 1 and 1.4 V using either a phosphate-buffered solution or NaCl solution as the catholyte. By increasing the reactor size from 500 mL to 1000 mL, a decrease in the ammonia recovery efficiency from 47 to 42 % was observed. The results also showed that the phosphate-buffered solution is preferable as the catholyte and that the voltage applied does not have a noticeable effect on current production and ammonia recovery. Low biodegradability of the wastes was identified as the main bottleneck. This research was supported by the European Union Horizon 2020 Research and Innovation Programme (GA nº 668128-Newfert-H2020-BBI-PPP-2014-1). Financing: This project has received funding from the Bio Based Industries Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 66812

Graphene oxide electrodeposited electrode enhances start-up and selective enrichment of exoelectrogens in bioelectrochemical systems

15 p.This study seeks to assess the impact that the anodic electrodeposition of graphene oxide (GO) has on the start-up process and on the development of microbial communities on the anode of BESs. The GO electrodeposited electrodes were characterised in abiotic conditions to verify the extent of the modifcation and were then transferred to a bioelectrochemical reactor. Results showed that the modifed electrode allowed for a reduced start-up time compared to the control electrode. After three months, high throughput sequencing was performed, revealing that electrochemically reduced graphene oxide acts as a selective agent toward exoelectrogenic bacteria as Geobacter. Overall, this study shows that GO modifed electrodes enhance bioflm build up in BES. This research was possible thanks to the financial support of the ‘Ministerio de Economía y Competitividad’ project ref: CTQ2015-68925-R, cofinanced by FEDER funds. Ana Sotres thanks the regional ‘Junta de Castilla y León’ for the postdoctoral contract associated with project ref: LE060U16, cofinanced by FEDER fundsS

Hydrogen evolution in microbial electrolysis cells treating landfill leachate: Dynamics of anodic biofilm

P. 13051-13063This study investigates the potential opportunities of hydrogen evolution treating landfill leachate in a set of two microbial electrolysis cells (MEC-1 and 2) under 30 C and 17 ± 3 C temperatures, respectively. The system achieved a projected current density of 1000e1200 mA m 2 (MEC-1) and 530e755 mA m 2 (MEC-2) coupled with low cost hydrogen production rate of 0.148 L La 1 d 1 (MEC-1) and 0.04 L La 1 d 1 (MEC-2) at an applied voltage of 1.0 V. Current generation led to a maximum COD oxidation of 73 ± 8% (MEC-1) and 65 ± 7% (MEC-2) with 100% energy recovery. The system also exhibited a high hydrogen recovery (66e95%), pure hydrogen yield (98%) and tremendous working stability during two months of operation. Electroactive microbes such as Pseudomonadaceae, Geobacteraceae and Comamonadaceae were found in anodophilic biofim, along with Rhodospirillaceae and Rhodocyclaceae, which could be involved in hydrogen production. These results demonstrated an energy-efficient approach for hydrogen production coupled with pollutants removal. This research was supported by the regional government ‘Junta de Castilla y León, Consejería de Educación’ and Ana Sotres thanks for the postdoctoral contract associated with project reference: LE060U16, co-financed by FEDER fund

The impact of externally added hydrogen gas on microbial electrosynthesis from CO2

Hydrogen is a key versatile biomolecule in microbial electrosynthesis (MES). It can be directly produced by electrolysis to be used as an intermediate, directly biosynthesize by electroactive microorganisms from protons and electrons, or externally added to drive other bioelectrochemical or biological reactions. The aim of this study is to bring further understanding on how externally added hydrogen impacts product formation on MES. Two double-chamber microbial electrolysis cells were built in 500mL modified Schott-Duran bottles (Figure 1A). The cathode consisted of a 175 cm2 carbon felt (+1V vs. Ag/AgCl) and a platinum wire was used as counter electrode. The cathode was inoculated according to the procedure detailed in Bajracharya et al. 2017, and following the acclimation period the biocathode was fed with a gas mixture containing 20% H2 / 20% N2 / 60% CO2. After 2 weeks of operation hydrogen was removed from the feed ( 20% N2 / 80% CO2). When the cell was fed with the hydrogen-containing mixture, acetate and ethanol concentrations (Figure 1B) grew steadily with time (composition ratio around 1:1 (w/w)). This behavior suggested that hydrogen was acting as a reducing agent driving direct production of ethanol, or even its production from acetate. However, when hydrogen was removed from the feed, ethanol concentration declined, while acetate concentration sharply increased showing CO2-acetate selectivities near 100%. These results indicate how ethanol production is highly dependent on externally-added hydrogen, while the synthesis of acetate only requires the cathode as a source of electrons. A.Sotres thanks “Junta de Castilla y Leon” for postdoctoral contract associated to project ref: LE060U16, cofinanced by FEDER fund

A semi-pilot microbial electrolysis cell (MEC) for hydrogen production and pig-slurry valorization

The amounts of slurry and manure produced each year are steadily rising as a result of an increasing demand for livestock products, which are expected to almost double by 2050 [1]. This two byproducts of farm-activity are commonly used as a fertilizer for crops production. However, their direct disposal may also overcome soils capacity to absorb nutrients in some areas [2], thus giving to rise to health and environmental issues. This demands the use of feasible and efficient waste management technologies that help to limit the impact of these wasteThis project has received funding from the Bio Based Industries Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 66812

Recuperación de nutrientes para producción de fertilizantes mediante sistemas bioelectroquímicos

El desarrollo de celdas microbianas para la recuperación de nutrientes es un paso crucial para la implementación de esta tecnología en el tratamiento de residuos orgánicos líquidos. En el presente trabajo se describen los resultados preliminares obtenidos durante la caracterización de un electrolizador biocatalíticos de 16 L, diseñado para el tratamiento de purines y recuperación de nitrógeno. El reactor fue alimentado con residuos de una granja de ganado porcino diluidos a diferentes concentraciones. Los resultados muestran que tras un periodo de aclimatación de 15-20 días es posible obtener recuperaciones máximas del 57 % del nitrógeno total presente en el residuo inicial.Financiación de Bio Based Industrires Joint Undertaking. H2020 research and innovation programme under grant agreement Nº 668128

Pilot-scale bioelectrochemical system for simultaneous nitrogen and carbon removal in urban wastewater treatment plants

[EN] This study aims to characterize the performance of a 150 L bioelectrochemical system-based plant, during the simultaneous carbon and nitrogen removal from several waste streams of wastewater treatment plants. The bioelectrochemical system (BES) contained five electrode pairs (operated hydraulically and electrically in parallel) and was fed with either wastewater, centrate (nutrient-rich liquid stream produced during the dewatering of digested biomass), or a mixture of both over 63 days, with a hydraulic retention time of one day. Total organic carbon and total nitrogen removal rates averaged 80% and 70%, respectively, with a specific energy consumption of 0.18 kWh·m−3 (BES + ancillary equipment). This work also underlines the challenges of using BES for nitrogen removal, highlighting the limitations of the current design, and suggesting some strategies for improvement.SIMinisterio de Educación, Cultura y Deport

A semi-pilot microbial electrolysis cell (MEC) for hydrogen production and pig-slurry valorization

The amounts of slurry and manure produced each year are steadily rising as a result of an increasing demand for livestock products, which are expected to almost double by 2050 [1]. This two byproducts of farm-activity are commonly used as a fertilizer for crops production. However, their direct disposal may also overcome soils capacity to absorb nutrients in some areas [2], thus giving to rise to health and environmental issues. This demands the use of feasible and efficient waste management technologies that help to limit the impact of these wastesThis project has received funding from the Bio Based Industries Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 66812

Scaling-up Bioelectrochemical Systems for nitrogen removal and recovery from waste streams = Escalado de sistemas bioelectroquímicos para eliminación y recuperación de nitrógeno en aguas residuales

179 p.El principal objetivo de esta tesis es estudiar el escalado de los sistemas bioelectroquímicos para reducir la materia orgánica y recuperar el nitrógeno contenido en corrientes de aguas residuales de alta carga de una manera energéticamente eficiente