Toluene biodegradation in an algal-bacterial airlift photobioreactor: Influence of the biomass concentration and of the presence of an organic phase

Producción CientíficaThe potential of algal-bacterial symbiosis for off-gas abatement was investigated for the first time by comparatively evaluating the performance of a bacterial (CB) and an algal-bacterial (PB) airlift bioreactors during the treatment of a 6 g m−3 toluene laden air emission. The influence of biomass concentration and of the addition of a non-aqueous phase was also investigated. A poor and fluctuating performance was recorded during the initial stages of the experiment, which was attributed to the low biomass concentration present in both reactors and to the accumulation of toxic metabolites. In this sense, an increase in the dilution rate from 0.23 to 0.45 d−1 and in biomass concentration from ∼1 to ∼5 g L−1 resulted in elimination capacities (ECs) of 300 g m−3 h−1 (corresponding to removal efficiencies ∼ 90%). Microalgae activity allowed for a reduction in the emitted CO2 and an increase in dissolved O2 concentration in the PB. However, excess biomass growth over 11 g L−1 hindered light penetration and severely decreased photosynthetic activity. The addition of silicone oil at 20% (on a volume basis) stabilized system performance, leading to dissolved O2 concentrations of 7 mg L−1 and steady ECs of 320 g m−3 h−1 in the PB. The ECs here recorded were considerably higher than those previously reported in toluene-degrading bioreactors. Finally, microbial population analysis by DGGE-sequencing demonstrated the differential specialization of the microbial community in both reactors, likely resulting in different toluene degradation pathways and metabolites production.Ministerio de Economía, Industria y Competitividad (Proyect CTM2015-70442-R)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA024U14 y UIC 71

Polyhydroxyalkanoates production from methane emissions in Sphagnum mosses: Assessing the effect of temperature and phosphorus limitation

Producción CientíficaThe isolation of highly efficient methanotrophic communities is crucial for the optimization of methane bioconversion into products with a high market value such as polyhydroxyalkanoates (PHA). The research here presented aimed at enriching a methanotrophic consortium from two different inocula (Sphagnum peat moss (Sp) and Sphagnum and activated sludge (M)) able to accumulate PHA while efficiently oxidizing CH4. Moreover, the effect of the temperature and phosphorus limitation on the biodegradation rate of CH4 and the PHA accumulation potential was investigated. Higher CH4 degradation rates were obtained under P availability at increasing temperature (25, 30 and 37 °C). The biomass enriched from the mixed inoculum always exhibited a superior biodegradation performance regardless of the temperature (a maximum value of 84.3 ± 8.4 mg CH4 h−1 g biomass−1 was recorded at 37 °C). The results of the PHB production showed that phosphorus limitation is required to promote PHB accumulation, the highest PHB content being observed with the Sphagnum inoculum at 25 °C (13.6 ± 5.6%). The differential specialization of the microbial communities depending on the enrichment temperature supported the key role of this parameter on the results obtained. In all cases after the completion of the enrichment process and of the P limitation tests, Methylocystis, a type II methanotroph known for its ability to accumulate PHA, was the genus that became dominant (reaching percentages from 16 to 46% depending on the enrichment temperature). Thus, the results here obtained demonstrated for the first time the relevance of the temperature used for the enrichment of the methanotrophic bacteria to boost PHA production yields under P limiting condition, highlighting the importance of optimizing culture conditions to improve the cost-efficiency of bioprocesses based on using methane as the primary feedstock for the PHA industrial market.Ministerio de Economía, Industria y Competitividad - FEDER (Project CTM2015-73228-JIN)Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. UIC 71 and CLU 2017-09

Does endovascular treatment with curative intention have benefits for treating High-grade AVM versus radiosurgery? Efficacy, safety, and cost-effectiveness analysis

BACKGROUND: The treatment of high-grade arteriovenous malformations (AVMs) remains challenging. Microsurgery provides a rapid and complete occlusion compared to other options, but is associated with undesirable morbidity and mortality. The aim of this study was to compare the occlusion rates, incidence of unfavorable outcomes, and cost-effectiveness of embolization and stereotactic radiosurgery (SRS) as a curative treatment for high-grade AVMs.METHODS: A retrospective series of 57 consecutive patients with high-grade AVM treated with embolization or SRS, with the aim of achieving complete occlusion, was analyzed. Demographic, clinical, and angio-architectonic variables were collected. Both treatments were compared for the occlusion rate and procedure-related complications. In addition, a cost-effectiveness analysis was performed.RESULTS: Thirty (52.6%) patients were men and 27 (47.4%) were women (mean age 39 years). AVMs were unruptured in 43 (75.4%) patients, and ruptured in 14 (24.6%) patients. The presence of deep venous drainage, nidus volume, perforated arterial supply, and eloquent localization were more frequent in the SRS group. Complications such as hemorrhage or worsening of previous seizures were more frequent in the embolization group. No significant differences were observed in the occlusion rates or in the time necessary to achieve occlusion between the groups. The incremental cost-effectiveness ratio for endovascular treatment vs. SRS was $ 53.279.CONCLUSION: Both techniques achieved similar occlusion rates, but SRS carried a lower risk of complications. Staged embolization may be associated with a greater risk of hemorrhage, while SRS was demonstrated to have a better cost-effectiveness ratio. These results support SRS as a better treatment option for high-grade AVMs

The effect of temperature during culture enrichment on methanotrophic polyhydroxyalkanoate production

Producción CientíficaClimate change and plastic pollution are likely the most relevant environmental problems of the 21st Century. Thus, one of the most promising solutions to remedy both environmental problems simultaneously is the bioconversion of greenhouse gases, such as methane (CH4), into bioplastics (PHAs). However, the optimization of this bioconversion platform is still required to turn CH4 biotransformation into a cost-effective and cost-competitive process. In this context, the research presented here aimed at elucidating the best temperature culture conditions to enhance both PHA accumulation and methane degradation. Six different enrichments were carried out at 25, 30 and 37 °C using different inocula and methane as the only energy and carbon source. CH4 biodegradation rates, specific growth rates, PHA accumulations and the community structure were characterized. Higher temperatures (30 and 37 °C) increased the PHAs accumulation up to 30% regardless of the inoculum. Moreover, Methylocystis became the dominant genus (∼30% of the total population) regardless of the temperature and inoculum used. This research demonstrated for the first time the fundamental role of temperature in increasing both the accumulation of PHAs and methane abatement during the enrichment of PHA cell-factories from methane, thus enhancing the cost-effectiveness of the process.Ministerio de Economía, Industria y Competitividad, TheEuropean FEDER program and the European Commission (CTM2015-73228-JIN, H2020-MSCA-IF-2016: CH4BioVal-GA:750126 and Red NOVEDAR)

Optimization of nitrogen feeding strategies for improving polyhydroxybutyrate production from biogas by Methylocystis parvus OBBP in a stirred tank reactor

Producción CientíficaThe design of efficient cultivation strategies to produce bioplastics from biogas is crucial for the implementation of this biorefinery process. In this work, biogas-based polyhydroxybutyrate (PHB) production and CH4 biodegradation performance was investigated for the first time in a stirred tank bioreactor inoculated with Methylocystis parvus OBBP. Decreasing nitrogen loading rates in continuous mode and alternating feast:famine regimes of 24 h-cycles, and alternating feast:famine regimes of 24 h:24 h and 24 h:48 h were tested. Continuous N feeding did not support an effective PHB production despite the occurrence of nitrogen limiting conditions. Feast-famine cycles of 24 h:24 h (with 50% stoichiometric nitrogen supply) supported the maximum PHB production (20 g-PHB m−3 d−1) without compromising the CH4-elimination capacity (25 g m−3 h−1) of the system. Feast:famine ratios ≤1:2 entailed the deterioration of process performance at stoichiometric nitrogen inputs ≤60%.Ministerio de Ciencia, Innovación y Universidades (grant BES-2016-077160)Ministerio de Ciencia, Innovación y Universidades (project CTM2015-70442-R)Junta de Castilla y León (projects UIC 071 and CLU 2017–09

Photosynthetic biogas upgrading to bio-methane: Boosting nutrient recovery via biomass productivity control

Producción CientíficaA pilot high rate algal pond (HRAP) interconnected to an external CO2–H2S absorption column via settled broth recirculation was used to simultaneously treat a synthetic digestate and to upgrade biogas to a bio-methane with sufficient quality to be injected into natural gas grids. An innovative HRAP operational strategy with biomass recirculation based on the control of algal-bacterial biomass productivity (2.2, 4.4 and 7.5 g m− 2 d− 1) via settled biomass wastage was evaluated in order to enhance nutrient recovery from digestate at a constant hydraulic retention time. The influence of the recycling liquid to biogas (L/G) ratio on the quality of the upgraded biogas was assessed. The bio-methane composition under a L/G ratio of 1 (0.4 ± 0.1% CO2, 0.03 ± 0.04% O2, 2.4 ± 0.2% N2 and 97.2 ± 0.2% CH4) complied with the technical specifications of most European bio-methane legislations regardless of the biomass productivity established. The HRAP operational strategy applied allowed increasing the N and P recovery from 19 and 22% to 83 and 100%, respectively, when the biomass productivity was increased from 2.2 to 7.5 g m− 2 d− 1. Finally, the dynamics of microalgae and bacteria population structure were characterized by morphological identification and Denaturing Gradient Gel Electrophoresis analysis.Ministerio de Economía, Industria y Competitividad (Proyect CTM2015-70442-R

Features and Origin of Red Clays in Castafiar Cave: A Touch of Colour

In Castaiiar Cave (Caceres, Spain), coatings of red clays cover the walls of the chambers, coexisting with diverse speleothems of aragonite, calcite, huntite and dolomite. The mineralogy of the clays is mainly illite, chlorite, kaolinite, smectite, quartz and Fe oxides and hydroxides such as goethite. They can be transported into the cave by infiltration waters or form by in situ alteration of the host rock: layers of dolomite rich in Fe and magnesite interbedded with greywackes and shales. Present-day hydrological conditions in the cave and conditions during the formation of speleothems have determined that the clays have not been transported by any flooding or seepage, but mostly staying in situ, and not included into carbonate crystal forms . Thus, most of the well-preserved speleothems are white and not stained, conforming an interesting chromatic contrast with the red clays that represent an additional attraction in this show cave

Euapta godeffroyi (Holothuroidea: Synaptidae): Filling the distribution gap between Mexico and Costa Rica, eastern tropical Pacific

One specimen of the sea cucumber Euapta godeffroyi (Semper, 1868) is reported from La Entrega reef (15°44´34´´ N, 96°07´35´´ W), Southern Mexican Pacific. The specimen was observed feeding late at night, supporting the nocturnal habits of this species which is a deposit feeder. No specimens of this species had been previously reported for the area extending from Isla Isabel, Mexico (21°51´43´´ N, 105°53´28´´ W) to Golfito, Costa Rica (8°37´02´´ N, 83°09´01´´ W); the new record fills part of its distribution gap in the eastern tropical Pacific

Microstructure and indentation hardness study of CAE-PVD (Cr,Ti,Al)N solid solution coatings deposited using a combinatorial multitarget approach

In this study we have analysed the indentation hardness and modulus of cathodic arc deposited CrTiAlN coatings as a function of the stoichiometric variables Ti/Cr, Al content and cation mix. The coatings have been prepared using a combinatorial cathode composition approach, leading up to 14 different stoichiometries produced in 5 batches. The coatings have been inspected by glow discharge optical emission spectroscopy, scanning electron microscopy, X-ray diffraction and nanoindentation techniques. The coatings develop crystalline structures compatible with solid solutions of face-centered cubic unit cells for all the compositions produced. Such unit cells exhibited a downwards lattice parameter dependency on the aluminum concentration of the coatings (from 0.417 nm down to 0.413 nm). The indentation hardness as a function of the Ti/Cr is compatible with other previous studies reported. The films hardnesses and moduli also increase as the aluminum concentration increases (21 GPa up to 34 GPa). Both indentation responses upon Ti/Cr and Al are attributed to solid solution strengthening. However in order to prove this statement, the indentation hardness and modulus were studied as a function of the mixing term of the cations, as this term is well representative of the solid solution compositional map. The observed results unambiguously evidence that the solid solution strengthening effect is confirmed on the basis of the dependency between the indentation hardness and the so called degree of mixing.This work has been funded by the Spanish Ministry of Science and Innovation of Spain through the project PGC2018-096855-A-C44. The authors also acknowledge the Centro para el Desarrollo Tecnológico e Industrial (CDTI) for the support of the excellence program CERVERA through the project CER2019-1003

Human impacts on the Northern Iberian Coast: Brominated pollutants.

Plastic and textile products as well as electronical devices are easily flammable products and to reduce fire-related injury and property damage, such materials are commonly covered by the so-called flame retardants (FR). The brominated flame retardants (BFRs) are the largest market group because of their low cost and high-performance efficiency. Nevertheless, as these compounds are additive rather than chemically bound to the products, they can be released into the environment and because they are toxic and persistent organic chemicals and can bioaccumulate, they have become contaminants of concern detectable in the environment, in animals, and in humans. PBDEs (Polybrominated Diphenyl Ethers) are a group of 209 different congeners used as FR and since 2004 banned in the EU. In spite of banned and restriction such chemicals are still detected in the environment and their monitoring necessary. In 2016 a sampling campaign was carried out covering the North Spanish Atlantic coast from the border with Portugal to the limit with France. The collected sediments were studied to determine sediment characteristics and PBDEs concentrations. Sedimentological characteristics including grain size distribution and total organic content were measured. Gas chromatography coupled to MS detector was used to perform the analytical analysis under QA/QC to guarantee the quality of the results. BDE28, BDE47, BDE66, BDE85, BDE99, BD100, BD153, BDE154 andBD183 have been determined and evaluated against Background assessment criteria (BACs) and Federal Environmental Quality Guidelines (FEQGs). Levels found demonstrate that there is still detectable presence of PBDEs in marine sediments albeit they are well below the FEQG and even frequently below BACs