Gestión de la prevención de riesgos laborales: Legislación, elementos, de OHSAS 18001 a ISO 45001

Presentación sobre sistemas de gestión de seguridad y salud en el trabajo. Incluye la legislación básica, los elementos que deben conformar el sistema, algunas pinceladas sobre el estándar OHSAS 18001 que han aplicado numerosas empresas a nivel mundial y requisitos de la nueva norma ISO 45001 que ha surgido a partir de OHSAS

PCDD/F formation from chlorophenols by lignin and manganese peroxidases

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) formation was studied, in vitro, with two different chlorophenol mixtures (group “di+tri” 2,4-dichlorophenol; 2,3,4-, 2,3,5-, and 3,4,5-trichlorophenols and group “tri+tetra+penta” with 2,4,5-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol) and two different lignolytic enzymes, lignin and manganese peroxidase (LiP and MnP respectively), which can be found during the composting process of sewage sludge. The concentrations of PCDD/F in final samples are compared to the PCDD/F content of the control samples containing the chlorophenols. High increases were observed for experiments with MnP and phosphate buffer. Experiments that contained tri-, tetra- and pentachlorophenol with MnP resulted in more than 8 · 108 ng of OCDD kg−1 chlorophenol which was much higher than the initial amount (1 · 107 ng OCDD kg−1 chlorophenol). In relation to LiP experiments, only those at 37 °C showed a moderate increase (from 1.3 · 107 to 2.6 · 107 ng of OCDD kg−1 chlorophenol). The results agree with the literature in which high amounts of HpCDD and OCDD were found after a composting process and could explain the biogenic formation suggested by others, but the incidence on the total toxicity is less than that expected.The authors want to thank the University of Alicante for their economic support to perform this research and the project CTQ 2008-05520 of the Spanish Ministry of Science and Innovation, Prometeo 2009/043/FEDER of the Valencian Community of Spain

Analysis of the vaporization process in TG apparatus and its incidence in pyrolysis

An analysis of the evaporation process of n-hexadecane in a thermogravimetric apparatus was carried out. n-Hexadecane represents a typical example of a high boiling point compound and its study is interesting for understanding those processes where vaporization takes place in parallel with pyrolysis during thermal treatment. The process has been studied under different operating conditions: nitrogen and air atmospheres, and isothermal and dynamic runs with three different heating rates from 5 K/min to 20 K/min. The experimental data were satisfactorily correlated to a n-order model with zero process order and the same apparent activation energy for all runs, but the exponential factors of the different runs depended on the initial mass and the heating rate. The experimental results were compared with those predicted considering the diffusion process inside the crucible, taking into account the vapor pressure and the diffusion coefficient of n-hexadecane. A parameter, product of these two variables, can be estimated from a single TG run, so the vaporization process in other equipment and/or operating conditions can also be estimated.Support for this work was provided by PROMETEO/2009/043/FEDER and ACOMP2010/075 of Generalitat Valenciana (Spain) and CTQ2008-05520 (Spanish MCI/research)

Characterization of lorry washing sludge

The sludge generated by washing lorry refuse and some fractions of municipal solid waste have been studied, to justify that washing sludge presents no danger and can therefore be managed adequately in a landfill, as well as other municipal solid waste fractions. One problem attributed to this type of sludge is its high level of sulfide content, which causes this waste to be considered hazardous. The determination of sulfide content in the studied samples was carried out according to environmental protection agency methods 9030B and 9034, and the results show that the sulfide concentration in the sludge is less than other fractions of the municipal solid waste treatment plants, which can properly composted, in which sulfides are oxidized to sulfates. Lorry washing sludge could therefore be managed in a municipal solid waste treatment plant

Assessing the relevance of higher education courses

The establishment of the European Higher Education Area has involved specifying lists of professional competencies that programs are expected to develop, and with this the need for procedures to measure how every course within a higher education program is aligned with the program’s competencies. We propose an instrument for characterizing this alignment, a process that we call assessing the relevance of a course. Using information from the course syllabus (objectives, contents and assessment scheme), our instrument produces indicators for characterizing the syllabus in terms of a competence list and for assessing its coherence. Because assessment involves quality, the results obtained can also be used to revise and improve the course syllabus. We illustrate this process with an example of a methods course from a mathematics teacher education program at a Spanish university

Dechlorination of polyvinyl chloride electric wires by hydrothermal treatment using K2CO3 in subcritical water

Polyvinyl chloride (PVC) waste generation has significantly increased in recent years and their disposal is considered a major environmental concern. Removal techniques of chlorine from PVC waste are being studied to minimize a negative environmental impact. In this work, the use of K2CO3 as an alkaline additive to improve the dechlorination efficiency (DE) in the hydrothermal degradation of PVC wires was studied. Different experiments were carried out varying both temperature (175, 200, 225, 235 and 250 °C) and K2CO3 concentration (0.025, 0.050 and 0.125 M), using a solid/liquid ratio of 1:5 in order to determine the evolution of the dechlorination efficiency with time. About 4.66, 21.1, 24.4, 45.7 and 92.6 wt% of chlorine in PVC wire was removed during hydrothermal dechlorination (HTD) with an additive/chlorine ratio of 1:25 (K2CO3 solution of 0.050 M) at 175, 200, 225, 235 and 250 °C, respectively. Optimal additive/chlorine ratio decreased to 1:50 (K2CO3 solution of 0.025 M) at 250 °C, obtaining a dechlorination degree of 99.1% after 4 h without the need of metallic catalysts. Concerning the solid phase behavior during dechlorination, a linear correlation between the DE reached and the weight loss of PVC was found.Support for this work was provided by the CTQ2016-76608-R project and the scholarship BES-2017-080382 from the Ministry of Economy Industry and Competitiveness (Spain)

Debromination and Reusable Glass Fiber Recovery from Large Waste Circuit Board Pieces in Subcritical Water Treatment

The great economic, social, and environmental interest that favors an effective management of the recycling of waste printed circuit boards (WCBs) encourages research on the improvement of processes capable of mitigating their harmful effects. In this work, the debromination of large WCBs was first performed through a hydrothermal process employing potassium carbonate as an additive. A total of 32 runs were carried out at 225 °C, various CO32–/Br– anionic ratios of 1:1, 2:1, 4:1, and 6:1, treatment times from 30 to 360 min, proportion of submerged WCBs in the liquid of 100, 50, and 25% that corresponded with the use of three WCB sizes of 20 mm × 16.5 mm, 20 mm × 33 mm, and 80 mm × 33 mm, respectively, and solid/liquid ratios of 1:2 and 1:1 g/mL without other metallic catalysts. A debromination efficiency of 50 wt % was reached at only 225 °C (limited by mechanical reasons) and 360 min, using a CO32–/Br– anionic ratio of 4:1 and a solid/liquid ratio of 1:2 for a large WCB with only 25% of its volume submerged in the liquid. This means conservation of water and energy compared to previous studies. A muffle furnace was used later to thermally treat a total of 101 debrominated samples, at constant temperature or following a temperature scaling program. An estimated decrease in resistance to rupture of glass fibers of only around 50% was accomplished by following a temperature scaling program up to 475 °C, obtaining clean glass fibers of large size. The simple techniques proposed to obtain reusable glass fibers from WCBs as large as the size of the reactor allows (as it might be in their original size) could significantly improve interest in the industry.Support for this work was granted by the PID2019-105359RB-I00 project and the scholarship BES-2017-080382 from the Ministry of Science and Innovation of Spain and project UAUSTI20-05 from the University of Alicante

Caracterización y evaluación de diseños de planes de formación inicial de profesores de matemáticas en el marco del espacio europeo de educación superior

Este estudio forma parte de un proyecto más general dedicado al diseño de instrumentos para determinar la calidad de planes de formación inicial de profesores de matemáticas de secundaria en el contexto español. Una de las dimensiones que empleamos para conocer la calidad del plan de formación es su relevancia, es decir, el grado en el que el plan se adecua a los requerimientos y expectativas del entorno y de sus participantes. En este capítulo presentamos la caracterización operativa de relevancia que hemos adoptado tomando como referentes la lista de competencias genéricas del Proyecto Tuning (González & Wagenaar, 2003) y la lista de competencias específicas que el Subcomité Español ICMI recomienda desarrollen los futuros profesores de matemáticas (Recio, 2004). Caracterizamos los tres indicadores de relevancia que usamos para medir el grado de presencia de dichas competencias en los objetivos del plan: la frecuencia con la cual los objetivos contemplan las diferentes las competencias, el tiempo dedicado a su consecución y su ponderación en la evaluación. Finalmente, ejemplificamos el cálculo de estos indicadores en las universidades participantes y, basándonos en ellos, formulamos algunas conclusiones sobre el papel de la noción de relevancia para caracterizar y evaluar diseños de programas de formación

PCDD/F determination in sewage sludge composting. Influence of aeration and the presence of PCP

Composting of sewage sludge is a common practice for sludge disposal. Some previous studies found high levels of polychorodibenzo-p-dioxins and polychorodibenzofurans (PCDD/Fs) after composting, especially octachlorodibenzo-p-dioxin (OCDD) but also 1234678-heptachlorodibenzo-p-dioxin (1234678-HpCDD) to a lesser extent. In this work, the concentrations of OCDD, 1234678-HpCDD and the rest of the 17 toxic congeners of PCDD/Fs were determined in compost obtained under different conditions. Although the toxicity of the two compounds mentioned above is small, their generation may reach undesirable levels. The PCDD/F content was analyzed in a composting plant and in a laboratory test. In both cases, the composted material was a mixture of sewage sludge, straw and sawdust. The composting plant was a tunnel with air turbine aeration and with a turner to homogenize and move the mixture upwards. The laboratory tests were carried out with Dewar vessels (with air dispersion at the bottom and controlled temperature) and with small vessels inside a controlled oven with non-forced aeration. The laboratory runs were also carried out with the addition of pentachlorophenol in some runs, as a dioxin precursor. The highest OCDD levels were found in three samples of the composting plant (30000–90000 pg/g dry matter or dm), with toxicity values surpassing the limit level for soil amendment (17 pg I-TEQ/g dm). Their formation was analyzed considering their concentration vs. that of octachorodibenzofuran (OCDF), which is not formed during composting. In the laboratory, in experiments carried out in a vessel with non-forced aeration conditions and with the addition of pentachlorophenol, the formation of OCDD was significant (e.g. from 80 to 1500 pg/g dm). That means that these two factors, non-forced aeration and the presence of pentachlorophenol, can cause the OCDD formation.Support for this work was provided by Research project GRE 13-14 from the University of Alicante, Research project PROMETEOII/2014/007 from the Generalitat Valenciana (Spain) and Research project CTQ2013-41006-R from the Ministry of Economy and Competitiveness (Spain)

Quality in mathematics teachers training syllabuses

The purpose of this study is to design instruments to measure the quality of prospective mathematics teachers training plans, within the Spanish context. We conceive the quality of a syllabus as a multidimensional concept that can be articulated by means of dimensions and competences