The generation of energy through the transformation of polluting waste is a widely explored field and offers advances in green technologies. One of the promising technologies is Microbial Fuel Cells (MFCs). These cells can contain electroactive microorganisms that transform organic waste into electricity by transferring electrons from their metabolism. In this study, a new bacterium capable of producing electricity from the waste of the poultry sector and using copper electrodes, called Av_G1, was identified and isolated. It is phylogenetically related to Citrobacter freundii and Citrobacter Murlinae. This new strain was identified molecularly, biochemically, and phylogenetically; its physiological and morphological characteristics were also studied through a Scanning Electron Microscope (SEM). Biochemical determination was performed using Simmons Citrate Agar, Lysine Iron Medium (L.I.A.), Motility/Ornithine Test, Methyl Red indicator, Enzymes: oxidase and catalase, and Gram stain test. The phylogenetic inference was deduced by bioinformatics tools (MEGA X, JalView, Clustal Omega) and the genetic databases The Ribosomal Database Project—RDP and the National Center for Biotechnology Information (NCBI). A maximum current potential of 0.645 V, a maximum current density of 168.72 ± 14.07 mA/m², and a power density of 31.05 mW/m² were recorded. During the monitoring, the physicochemical parameters were taken: pH, Oxide Reduction Potential (ORP), Dissolved Oxygen (DO), conductivity, Total Solids (TDS), and average temperature were recorded. Therefore, the present study shows a new Gram-negative electrogenic bacterium, which can be used for electrochemical processes and applied in MFC with copper electrodes.

The tanning industry generates effluents with high chromium content, which require treatment prior to discharge into the sewage system. This article explores the use of magnetic magnetite nanoparticles (MNPs) to remove Cr(VI) from aqueous solutions, such as tanning effluents. The MNPs were synthesized by coprecipitation reaction using the Olea europaea extract as a reducing agent. Subsequently, they were characterized by dynamic light scattering spectroscopy (DLS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). MNPs with irregular morphology and diameters ranging from 73.28 to 162.90 nm were obtained. Cr(VI) removal was performed using jar test methodology, and its efficiency was evaluated in the laboratory for different initial Cr(VI) (mg/L) concentration and nanoparticle (g/L) concentration. A kinetic study was developed and indicated that the equilibrium adsorption mechanism corresponds to a pseudo-second-order model. Furthermore, the isotherm analysis revealed that chromium adsorption best fits the Langmuir isotherm. Finally, Cr(VI) removal rates from 85% to 100% were achieved in tanning and retanning effluents.

There is a fundamental interest in studying travertine rocks, and this is to understand their structure, their geomechanical behavior and other particularities in order to guarantee their proper use in different engineering and architectural applications, and thus, evaluate the sustainability of the travertines, natural resources, the stability of slopes, the preservation of cultural heritage and the mitigation of possible anthropic risks. Travertine has petrological and mechanical properties similar to carbonates from oil fields such as those found in El Presal-Brazil, which currently contain the largest hydrocarbon reserves in the world. Given the impossibility of obtaining rock samples from this deposit to carry out the study, rocks similar to these were used. The present study specifically used samples of Lapis tiburtinus rocks, coming from the west of the city of Tivoli in Italy and these showed resistance to uniaxial and triaxial compression, and showed mechanical resistance due to increased porosity and brittleness. The investigation carried out an analysis of the geomechanical behavior travertine through an experimental program, which includes a petrological, structural, and mechanical characterization. It was determined the travertine is mainly composed of micrite and spastic calcite without the presence of grains or allochemical cements and presents high porosity of the fenetral and vulgar type. Macro and micropores were found to be chaotically distributed in the rock and have low connectivity, which demonstrates the complexity and heterogeneity of the porous structure of Roman travertine. Uniaxial and triaxial compressive strength tests were also carried out, observing a decrease in its mechanical strength due to the increase in porosity, presenting a property of brittleness in its behavior. The results were consistent and valid for this type of rock compared to other studies; determining that there is a correct and adequate operation of the triaxial cell used in the mechanical resistance tests.