The emergency closure of educational institutions, in the face of the health contingency due to Covid-19, has prompted the rethinking of the models of teaching competencies to adapt to virtual learning environments (VLE). The objective of this study is to design and validate a model of teaching competencies in VLE, with the support of virtual laboratories, to ensure the quality of higher education during the covid-19 pandemic. A quantitative and correlational methodology was used in a case study. The research is divided into two methodological moments: the design of the model and its validation. The instruments used were a comparative analysis matrix and a Likert-type scale. 5 650 students and 41 teachers participated in the validation cap. The results highlight the need for teacher development, mainly in digital and research skills. One weakness of the study is the lack of weighting of the quality indicators. The proposed model represents an innovation in the definition of indicators, in the form of competencies, for the assurance of educational quality in VLE. It is concluded that the proposed model is pertinent for the assurance of educational quality in VLE.

A native cyanide-degrading bacterial consortium was isolated from goldmine tailing sediments. Mine tailings are toxic effluents due to their metal–cyanide complexes. The bacterial consortium was able to degrade an initial sodium cyanide concentration ranging from 5 to 120 mg L⁻¹ in alkaline synthetic wastewater (pH > 9.2), for a maximum of 15 days. The free cyanide biodegradation efficiency was 98% for the highest initial free cyanide concentration tested and followed a first-order kinetic profile, with an estimated kinetic rate constant of 0.12 ± 0.011 d⁻¹. The cyanide-degrading consortium was streaked with serial dilutions on a specific medium (R2A). 16S rRNA gene sequencing and mass spectrometry proteomic fingerprinting of the isolates showed that the bacterial strains belonged to Microbacterium paraoxydans, Brevibacterium casei, Brevundimonas vesicularis, Bacillus cereus and Cellulosimicrobium sp. The first four genera had previously been identified as cyanide-degrading bacteria. Microbacterium and Brevibacterium had previously been found in alkaline conditions, showing resistance to heavy metals. As for Cellulosimicrobium, to our knowledge, this is the first study to implicate it directly or indirectly in cyanide biodegradation. In this research, these genera were identified as functional bacteria for cyanide degradation, and they might be suitable for mine tailing biotechnological tertiary treatment.

Mexico is characterized as a mining country since it is the world’s main silver producer. During its extraction, wastewater (mining tailings) is generated which contains cyanide and heavy metals. The purpose of this research was to determine whether a bacterial consortium isolated from a tailings dam can use cyanide as a source of nitrogen and carbon to carry out its biodegradation. The study determined the effects of three physicochemical factors (pH, temperature and inoculum concentration) and three metals (copper, iron and nickel) on cyanide biodegradation. The results showed that the highest cyanide removals were obtained when working with a pH of 9.5, a temperature of 25 °C and 15% v/v of inoculum (88%), while the optimum values for copper, iron and nickel were 0, 7.7 and 0.46 mg·L⁻¹, respectively, showing that copper causes an inhibitory effect (cyanide biodegradation of 68%) on the bacteria and consequently on the biological degradation of cyanide and that iron can promote the biodegradation of the pollutant by 91%.

A descriptive analysis of 416 documents was performed using bibliometric techniques, in order to gather existing knowledge in circular economy (CE) focusing on waste management (2007–2020). The results of this study indicate that annual scientific production increased 94% in the last five years; highlighting the countries of Italy, Spain, United Kingdom, China, Brazil and India. The conceptual analysis indicates strong linkage between CE and sustainable production, waste management and recycling. Emerging research trends evolved from processes and industry oriented approach (2017), towards waste management, recycling and circular economy (2019) and sustainable development and urban solid waste (2020). Through intellectual analysis, schools of thought were identified, where the most influential authors such as Wang, Ghisellini, Zhang and the European Commission with the greatest connection with other authors stand out. Results found denote the challenge represented by the implementation of comprehensive policies in CE, in addition to measure its contribution to sustainable development. The above, being a key alternative for green recovery in response to current COVID-19 pandemic.