Enhanced bioelectrochemical degradation of Thiabendazole using biostimulated Tunisian hypersaline sediments: kinetics, efficiency, and microbial community shifts.

Thiabendazole (TBZ), a recalcitrant fungicide, is frequently applied in postharvest fruit treatment and generates significant volumes of industrial wastewater (WW) that conventional treatment plants cannot handle. This explores a bioelectrochemical system (BES) for TBZ degradation using Tunisian hypersaline sediments (THSs) as inoculum. Four sets of BES, along with biological controls, were tested using THS subjected to different levels of TBZ biostimulation.

Insights into the local interaction mechanisms between fermenting broken maize and various binder materials for anaerobic digester structures.

Concrete structures of anaerobic digestion plants face chemically aggressive conditions due to the contact with the complex liquid fraction of the fermenting biowaste. This paper aims to determine the biogeochemical dynamic interaction phenomena at play between the biowaste and cementitious matrices at the local scale, and to identify durable binders in such environments. Binder materials likely to show increased durability - slag and calcium aluminate cement, and a metakaolin-based alkali-activated geopolymer - and a reference Portland cement were inserted into sealed bioeactors during 5 cycles (245 days) of broken maize anaerobic digestion.

How Comparable are Microbial Electrochemical Systems around the Globe? An Electrochemical and Microbiological Cross-Laboratory Study.

Invited for this month's cover is the collaborative work among Univ. of Milano-Bicocca, Ricerca sul Sistema Energetico S.p.

How bacteria use electric fields to reach surfaces.

Electrotaxis is the property of cells to sense electric fields and use them to orient their displacement. This property has been widely investigated with eukaryotic cells but it remains unclear whether or not bacterial cells can sense an electric field. Here, a specific experimental set-up was designed to form microbial electroactive biofilms while differentiating the effect of the electric field from that of the polarised electrode surface.

How Comparable are Microbial Electrochemical Systems around the Globe? An Electrochemical and Microbiological Cross-Laboratory Study.

A cross-laboratory study on microbial fuel cells (MFC) which involved different institutions around the world is presented. The study aims to assess the development of autochthone microbial pools enriched from domestic wastewater, cultivated in identical single-chamber MFCs, operated in the same way, thereby approaching the idea of developing common standards for MFCs. The MFCs are inoculated with domestic wastewater in different geographic locations.

Industrially scalable surface treatments to enhance the current density output from graphite bioanodes fueled by real domestic wastewater.

Acid and electrochemical surface treatments of graphite electrode, used individually or in combination, significantly improved the microbial anode current production, by +17% to +56%, in well-regulated and duplicated electroanalytical experimental systems. Of all the consequences induced by surface treatments, the modifications of the surface nano-topography preferentially justify an improvement in the fixation of bacteria, and an increase of the specific surface area and the electrochemically accessible surface of graphite electrodes, which are at the origin of the higher performances of the bioanodes supplied with domestic wastewater. The evolution of the chemical composition and the appearance of C-O, C=O, and O=C-O groups on the graphite surface created by combining acid and electrochemical treatments was prejudicial to the formation of efficient domestic-wastewater-oxidizing bioanodes.

Allochthonous and Autochthonous Halothermotolerant Bioanodes From Hypersaline Sediment and Textile Wastewater: A Promising Microbial Electrochemical Process for Energy Recovery Coupled With Real Textile Wastewater Treatment.

The textile and clothing industry is the first manufacture sector in Tunisia in terms of employment and number of enterprises. It generates large volumes of textile dyeing wastewater (TDWW) containing high concentrations of saline, alkaline, and recalcitrant pollutants that could fuel tenacious and resilient electrochemically active microorganisms in bioanodes of bioelectrochemical systems. In this study, a designed hybrid bacterial halothermotolerant bioanode incorporating indigenous and exogenous bacteria from both hypersaline sediment of Chott El Djerid (HSCE) and TDWW is proposed for simultaneous treatment of real TDWW and anodic current generation under high salinity.

Nitrate and nitrite bacterial reduction at alkaline pH and high nitrate concentrations, comparison of acetate versus dihydrogen as electron donors.

This study assesses bacterial denitrification at alkaline pH, up to 12, and high nitrate concentration, up to 400 mM. Two types of electron donors organic (acetate) and inorganic (dihydrogen) were compared. With both types of electron donors, nitrite reduction was the key step, likely to increase the pH and lead to nitrite accumulation.

Microfluidic Microbial Bioelectrochemical Systems: An Integrated Investigation Platform for a More Fundamental Understanding of Electroactive Bacterial Biofilms.

It is the ambition of many researchers to finally be able to close in on the fundamental, coupled phenomena that occur during the formation and expression of electrocatalytic activity in electroactive biofilms. It is because of this desire to understand that bioelectrochemical systems (BESs) have been miniaturized into microBES by taking advantage of the worldwide development of microfluidics. Microfluidics tools applied to bioelectrochemistry permit even more fundamental studies of interactions and coupled phenomena occurring at the microscale, thanks, in particular, to the concomitant combination of electroanalysis, spectroscopic analytical techniques and real-time microscopy that is now possible.

Adaptation of neutrophilic Paracoccus denitrificans to denitrification at highly alkaline pH.

Bacterial denitrification is widely documented at neutral pH in order to improve the removal of nitrate in wastewater treatment processes. However, certain industrial contexts generate alkaline waste and effluent containing nitrate that must be denitrified. To obtain more information on denitrification at alkaline pH, this study evaluated the possibility of adapting a neutrophilic denitrifying strain, Paracoccus denitrificans, to alkaline pH.

Influence of Hydrogen Electron Donor, Alkaline pH, and High Nitrate Concentrations on Microbial Denitrification: A Review.

Bacterial respiration of nitrate is a natural process of nitrate reduction, which has been industrialized to treat anthropic nitrate pollution. This process, also known as "microbial denitrification", is widely documented from the fundamental and engineering points of view for the enhancement of the removal of nitrate in wastewater. For this purpose, experiments are generally conducted with heterotrophic microbial metabolism, neutral pH and moderate nitrate concentrations (<50 mM).

Effect of pore size on the current produced by 3-dimensional porous microbial anodes: A critical review.

Microbial anodes are the cornerstone of most electro-microbial processes. Designing 3-dimensional porous electrodes to increase the surface area of the electroactive biofilm they support is a key challenge in order to boost their performance. In this context, the critical review presented here aims to assess whether an optimal range of pore size may exist for the design of microbial anodes.

Understanding the cumulative effects of salinity, temperature and inoculation size for the design of optimal halothermotolerant bioanodes from hypersaline sediments.

The main objective of this study was to understand the interaction between salinity, temperature and inoculum size and how it could lead to the formation of efficient halothermotolerant bioanodes from the Hypersaline Sediment of Chott El Djerid (HSCE). Sixteen experiments on bioanode formation were designed using a Box-Behnken matrix and response surface methodology to understand synchronous interactions. All bioanode formations were conducted on 6 cm carbon felt electrodes polarized at -0.

Evaluation of microbial proliferation on cementitious materials exposed to biogas systems.

Understanding the interactions between biofilm and cementitious materials in biogas production systems is an essential step toward the development of durable concrete for this expanding sector. Although the action of the liquid phase medium on the material has been the subject of several research studies, the possible impact of the material's properties on biofilm formation and composition has been little investigated, if at all. The aim of this paper is to evaluate the characteristics of the biofilm according to the surface properties of the materials.

Iron-Nicarbazin derived platinum group metal-free electrocatalyst in scalable-size air-breathing cathodes for microbial fuel cells.

In this work, a platinum group metal-free (PGM-free) catalyst based on iron as transitional metal and Nicarbazin (NCB) as low cost organic precursor was synthesized using Sacrificial Support Method (SSM). The catalyst was then incorporated into a large area air-breathing cathode fabricated by pressing with a large diameter pellet die. The electrochemical tests in abiotic conditions revealed that after a couple of weeks of successful operation, the electrode experienced drop in performances in reason of electrolyte leakage, which was not an issue with the smaller electrodes.

Microbial fuel cells: From fundamentals to applications. A review.

In the past 10-15 years, the microbial fuel cell (MFC) technology has captured the attention of the scientific community for the possibility of transforming organic waste directly into electricity through microbially catalyzed anodic, and microbial/enzymatic/abiotic cathodic electrochemical reactions. In this review, several aspects of the technology are considered. Firstly, a brief history of abiotic to biological fuel cells and subsequently, microbial fuel cells is presented.

Different methods used to form oxygen reducing biocathodes lead to different biomass quantities, bacterial communities, and electrochemical kinetics.

Six biocathodes catalyzing oxygen reduction were designed from the same environmental inoculum but using three different methods. Two were formed freely at open circuit potential, two using conventional aerobic polarization at -0.2V/SCE and two by reversion of already established acetate-fed bioanodes.

Mechanisms of cementitious material deterioration in biogas digester.

Digesters produce biogas from organic wastes through anaerobic digestion processes. These digesters, often made of concrete, suffer severe premature deterioration caused mainly by the presence of fermentative microorganisms producing metabolites that are aggressive towards cementitious materials. To clarify the degradation mechanisms in an anaerobic digestion medium, ordinary Portland cement paste specimens were immersed in the liquid fraction of a running, lab-scale digester for 4weeks.

Biocathodes reducing oxygen at high potential select biofilms dominated by Ectothiorhodospiraceae populations harboring a specific association of genes.

Biocathodes polarized at high potential are promising for enhancing Microbial Fuel Cell performances but the microbes and genes involved remain poorly documented. Here, two sets of five oxygen-reducing biocathodes were formed at two potentials (-0.4V and +0.

Multiple electron transfer systems in oxygen reducing biocathodes revealed by different conditions of aeration/agitation.

Oxygen reducing biocathodes were formed at -0.2V/SCE (+0.04V/SHE) from compost leachate.

Bilirubin oxidase based enzymatic air-breathing cathode: Operation under pristine and contaminated conditions.

The performance of bilirubin oxidase (BOx) based air breathing cathode was constantly monitored over 45 days. The effect of electrolyte composition on the cathode oxygen reduction reaction (ORR) output was investigated. Particularly, deactivation of the electrocatalytic activity of the enzyme in phosphate buffer saline (PBS) solution and in activated sludge (AS) was evaluated.

Multi-system Nernst-Michaelis-Menten model applied to bioanodes formed from sewage sludge.

Bioanodes were formed under constant polarization at -0.2 V/SCE from fermented sewage sludge. Current densities reached were 9.

Comparison of synthetic medium and wastewater used as dilution medium to design scalable microbial anodes: Application to food waste treatment.

The objective was to replace synthetic medium by wastewater as a strategy to design low-cost scalable bioanodes. The addition of activated sludge was necessary to form primary bioanodes that were then used as the inoculum to form the secondary bioanodes. Bioanodes formed in synthetic medium with acetate 10mM provided current densities of 21.

The current provided by oxygen-reducing microbial cathodes is related to the composition of their bacterial community.

Oxygen reducing biocathodes were formed from sludge under constant polarization at -0.2 and +0.4V/SCE.