Biodesulfurization of landfill biogas by a pilot-scale bioscrubber: Operational limits and microbial analysis.

Biogas serves as a crucial renewable energy vector to ensure a more sustainable energy future. However, the presence of hydrogen sulfide (H2S) limits its application in various sectors, emphasizing the importance of effective H2S removal techniques for maximizing its potential. In the present study, the limits of a pilot-scale bioscrubber for biogas desulfurization was study in a real scenario. An increase in the superficial liquid velocity resulted in significant improvements in the H2S removal efficiency, increasing from 76 ± 8% (elimination capacity of 6.2 ± 0.5 gS-H2S m-3 h-1) to 97.7 ± 0.5% (elimination capacity of 8 ± 1 gS-H2S m-3 h-1) as the superficial liquid velocity increased from 50 ± 3 m h-1 to 200 ± 8 m h-1. A USL of 161.4 ± 0.5 m h-1 was able to achieve outlet H2S concentrations as low as 3 ± 1 ppmv (H2S removal efficiency of 97 ± 1%) for 7 days. High superficial liquid velocity favoured the aerobic H2S oxidation reducing the nitrate demand. The maximum EC reached throughout the operation was 50.8 ± 0.6 gS-H2S m-3 h-1 (H2S removal efficiency of 96 ± 1%) and a sulfur production of 60%. Studies in batch flocculation experiments showed sulfur removal rates up to 97.6 ± 0.9% with a cationic flocculant dose of 75 mg L-1. Microbial analysis revealed that the predominant genus with sulfo-oxidant capacity during periods of low H2S inlet load was Thioalkalispira-sulfurivermis (61-69%), while in periods of higher H2S inlet load, family Arcobacteraceae was the most prevalent (11%).

A comparative assessment of treatment methods to release ferulic and p-cumaric acids from Brewer's Spent Grains.

Brewers' spent grain (BSG) is the main byproduct from the brewing industry, which accounts for 85 % of the total waste generated during beer production. This lignocellulosic material is traditionally used as livestock feed and sold at a low price. However, BSG can be used as a low-cost feedstock for the production of bioactive molecules and chemicals precursors, upgrading the value of this byproduct. In this context, BSG is a promising feedstock for the extraction of antioxidants like ferulic acid (FA) and p-coumaric acid (p-Cu). The effectiveness of three hydrolysis treatments were evaluated for the extraction of FA and p-Cu from BSG, namely enzymatic (based on the synergistic cooperation between a feruloyl esterase and an endo-1,4-ß-xylanase), alkaline and hydrothermal. The hydrothermal treatment produced the highest extraction yields (7.2 g/kgBSG and 1.4 g/kgBSG for FA and p-Cu, respectively) in a short extraction time (an hour). On the other hand, enzymatic hydrolysis extracted 4.3 g/kgBSG for FA and negligible yields for p-Cu in 4 h of incubation at 25 °C. Yields of 5.5 g/kgBSG for FA and 0.6 g/kgBSG for p-Cu were obtained in more than 5 h of alkaline treatment at 120 °C. The mass and energy balances revealed the high dependence of the operating costs on the concentration of BSG used during the extraction process, with costs of 34.5 €, 6607 € and 205.5 € per kg of FA for the chemical, enzymatic and hydrothermal extraction methods at 100 kg BSG/m3.

Recent advances in biological technologies for anoxic biogas desulfurization.

Recovery of the energy contained in biogas will be essential in coming years to reduce greenhouse gas emissions and our current dependence on fossil fuels. The elimination of H2S is a priority to avoid equipment corrosion, poisoning of catalytic systems and SO2 emissions in combustion engines. This review describes the advances made in this technology using fixed biomass bioreactors (FBB) and suspended growth bioreactors (SGB) since the first studies in this field in 2008. Anoxic desulfurization has been studied mainly in biotrickling filters (BTF). Elimination capacities (EC) up to 287 gS m-3 h-1 have been achieved, with a removal efficiency (RE) of 99%. Both nitrate and nitrite have been successfully used as electron acceptor. SGBs can solve some operational problems present in FBBs, such as clogging or nutrient distribution issues. However, they present greater difficulties in gas-liquid mass transfer, although ECs of up to 194 gS m-3 h-1 have been reported in both gas-lift and stirred tank reactors. One of the major disadvantages of using anoxic biodesulfurization compared to aerobic biodesulfurization is the need to provide reagents (nitrates and/or nitrites), with the consequent increase in operating costs. A solution proposed in this respect is the use of nitrified effluents, some ammonium-rich effluents nitrified include landfill leachate and digested effluent from the anaerobic digester have been tested successfully. Among the microbial diversity found in the bioreactors, the genera Thiobacillus, Sulfurimonas and Sedimenticola play a key role in anoxic removal of H2S. Finally, a summary of future trends in technology is provided.

Mild sensory symptoms during SARS-CoV-2 infection among healthcare professionals.

INTRODUCTION: It is not yet possible to estimate the proportion of patients with COVID-19 who present distinguishable classical neurological symptoms and syndromes. The objective of this study is to estimate the incidence of sensory symptoms (hypoaesthesia, paraesthesia, and hyperalgesia) in physicians who have presented the disease at Hospital Universitario Fundación Alcorcón (HUFA) in Madrid; to establish the relationship between sensory symptoms and the presence of other signs of infection; and to study their association with the severity of COVID-19. METHODS: We conducted a descriptive, cross-sectional, retrospective, observational study. HUFA physicians who presented SARS-CoV-2 infection between 1 March and 25 July 2020 were included in the study. A voluntary, anonymous survey was distributed via corporate email. Sociodemographic and clinical characteristics were collected from professionals with PCR- or serology-confirmed COVID-19. RESULTS: The survey was sent to 801 physicians and we received 89 responses. The mean age of respondents was 38.28 years. A total of 17.98% presented sensory symptoms. A significant relationship was found between the presence of paraesthesia and cough, fever, myalgia, asthaenia, and dyspnoea. A significant relationship was also found between paraesthesia and the need for treatment and admission due to COVID-19. Sensory symptoms were present from the fifth day of illness in 87.4% of cases. CONCLUSIONS: SARS-CoV-2 infection can be associated with sensory symptoms, mostly in severe cases. Sensory symptoms often appear after a time interval, and may be caused by a parainfectious syndrome with an autoimmunity background.

Effect of VOCs and methane in the biological oxidation of the ferrous ion by an acidophilic consortium.

During the elimination of H2S from biogas in an aqueous ferric sulphate solution, volatile organic compounds (VOCs) and methane are absorbed and may have an effect on the subsequent biological regeneration of ferric ion. This study was conducted to investigate the effect of maximum concentrations of methane and some VOCs found in biogas on the ferrous oxidation of an acidophilic microbial consortium (FO consortium). The presence and impact of heterotrophic microorganisms on the activity of the acidophilic consortium was also evaluated. No effect on the ferrous oxidation rate was found with gas concentrations of 1500 mg toluene m(-3), 1400 mg 2-butanol m(-3) or 1250 mg 1,2-dichloroethane m(-3), nor with methane at gas concentrations ranging from 15-25% (v/v). A tenfold increase in VOCs concentrations totally inhibited the microbial activity of the FO consortium and the heterotrophs. The presence of a heterotrophic fungus may promote the autotrophic growth of the FO consortium.

Simultaneous removal of ammonium from landfill leachate and hydrogen sulfide from biogas using a novel two-stage oxic-anoxic system.

Anoxic biodesulfurization has been achieved in several bioreactor systems that have shown robustness and high elimination capacities (ECs). However, the high operating costs of this technology, which are mainly caused by the high requirements of nitrite or nitrate, make its full-scale application difficult. In the present study, the use of biologically produced nitrate/nitrite by nitrification of two different ammonium substrates, namely synthetic medium and landfill leachate, is proposed as a novel alternative. The results demonstrate the feasibility of using both ammonium substrates as nutrient solutions. A maximum elemental sulfur production of 95 ±â€¯1% and a maximum H2S EC of 141.18 g S-H2S m-3 h-1 (RE = 95.0%) was obtained using landfill leachate as the ammonium source. Next Generation Sequencing (NGS) analysis of the microbial community revealed that the most common genera present in the desulfurizing bioreactor were Sulfurimonas (91.8-50.9%) followed by Thauera (1.1-24.2%) and Lentimicrobium (2.0-9.7%).

The spiral enteroscopy training initiative: results of a prospective study evaluating the Discovery SB overtube device during small bowel enteroscopy (with video).

BACKGROUND AND AIM: Indications for small-bowel enteroscopy are increasing, but advancing the endoscope to the ileum remains challenging, especially for less experienced operators. The aim was to evaluate the ease of use, safety, and efficacy of the Discovery SB overtube (Spirus Medical, Stoughton, Massachusetts, USA) during SB enteroscopy by physicians with no experience of the device. PATIENTS AND METHODS: Thirty-three "untrained" endoscopists performed spiral enteroscopy during one of four 2-day training modules. Data were prospectively collected. Patient demographics, depth and time to maximal insertion, total procedure time, and findings were recorded. Trauma was documented during scope withdrawal. Day 1 and day 2 results were compared. RESULTS: Ninety procedures were successfully performed in 95 patients (72.6 % women, age = 48.8 +/- 14.2 years). Endoscopists each performed a mean of five procedures. Mean time to maximal insertion was 20.9 +/- 6.4 minutes. Mean depth achieved was 262.0 +/- 57.4 cm. Total procedure time was 33.6 +/- 8.0 minutes. In 90.3 %, 94.6 %, and 83.9 % of patients, respectively, a trauma score less than 3 was recorded in the esophagus, stomach, and intestine (scale = 0 - 5). There were no perforations, nor significant associations between trauma score and patient age, body mass index, depth of insertion, time to maximal insertion, total procedure time, or day 1 vs. day 2 procedures. Depth of insertion was greater on day 2 than on day 1 (276.9 +/- 53.7 cm vs. 252.0 +/- 58.0 cm, P = 0.043). CONCLUSIONS: Discovery SB provides safe advancement of the enteroscope into the distal small bowel. Maximum depth of insertion appears comparable to that of balloon enteroscopy while taking less time. The device is easy to use and may be effectively operated in as few as five training cases.

Removal of hydrogen sulfide and ammonia from gas mixtures by co-immobilized cells using a new configuration of two biotrickling filters.

The simultaneous removal of H(2)S and NH(3) was investigated using two biotrickling filters packed with polyurethane foam cubes. One biotrickling filter was inoculated with Thiobacillus thioparus ATCC 23645 for the removal of H(2)S (BTT) and the other filter with Nitrosomonas europaea ATCC 19718 for the removal of NH(3) (BNE). Three different configurations were studied by modification of the gas line and recirculation medium line. The best results were obtained with the BNE biotrickling filter after the co-immobilization of the two bacteria. A removal efficiency of 100% for 230 ppmv of NH(3) and 129 ppmv of H(2)S was reached at an EBRT of 60 seconds. The results obtained show that it is possible to co-immobilize both microorganisms using the same recirculation medium and remove successfully H(2)S and NH(3) from a gas mixture.

Dimethyl sulphide degradation using immobilized Thiobacillus thioparus in a biotrickling filter.

Gaseous dimethyl sulphide (DMS) was eliminated in a biotrickling filter with Thiobacillus thioparus grown in polyurethane foam cubes as carrier material. The temperature, pH and empty bed residence time of the gas were maintained at 30 degrees C, 7.0 and 40 s, respectively. In the first 45 days, DMS loads of around 2.0 gDMS m(-3) h(-1) were fed to the BTF to adapt T. thioparus to DMS consumption, attaining close to 100% removal efficiency (RE) on day 46, and the maximum elimination capacity (EC) was 4.0 gDMS m(-3) h(-1) with a RE of 77%. The overall performance was enhanced by adding a nitrogen-enriched (9x) medium but was negatively affected by high superficial liquid velocity (8.18 m h(-1)) and high pH (>7.5). Sulphate concentrations (up to 10 g L(-1)) showed no effect. The system supported shock loads up to 58 gDMS m(-3) h(-1) with increased elimination. With nitrogen-enriched medium and a pH of 7.0 it was possible to increase the EC of DMS up to a maximum of around 23 gDMS m(-3) h(-1) with 65% RE.

Pretreatment Processes of Biomass for Biorefineries: Current Status and Prospects.

This article seeks to be a handy document for the academy and the industry to get quickly up to speed on the current status and prospects of biomass pretreatment for biorefineries. It is divided into two biomass sources: vegetal and animal. Vegetal biomass is the material produced by plants on land or in water (algae), consuming sunlight, CO2, water, and soil nutrients. This includes residues or main products from, for example, intensive grass crops, forestry, and industrial and agricultural activities. Animal biomass is the residual biomass generated from the production of food from animals (e.g., manure and whey). This review does not mean to include every technology in the area, but it does evaluate physical pretreatments, microwave-assisted extraction, and water treatments for vegetal biomass. A general review is given for animal biomass based in physical, chemical, and biological pretreatments.

Correlation of radiological and immunochemical parameters with clinical outcome in patients with recurrent glioblastoma treated with Bevacizumab.

BACKGROUND: Some phase 2 trials had reported encouraging progression-free survival with Bevacizumab in monotherapy or combined with chemotherapy in glioblastoma. However, phase 3 trials showed a significant improvement in progression free survival without a benefit in overall survival. To date, there are no predictive biomarker of response for Bevacizumab in glioblastoma. METHODS: We used Immunochemical analysis on tumor samples and pretreatment and post-treatment perfusion-MRI to try to identify possible predictive angiogenesis-related biomarkers of response and survival in patients with glioblastoma treated with bevacizumab in the first recurrence. We analyzed histological parameters: vascular proliferation, mitotic number and Ki-67 index; molecular factors: MGMT promoter methylation, EGFR amplification and EGFR variant III; immunohistochemical: MET, Midkine, HIF1, VEGFA, VEGF-R2, CD44, Olig2, microvascular area and microvascular density; and radiological: rCBV. RESULTS: In the statistical analysis, no significant correlation of any histological, molecular, microvascular or radiological parameters could be demonstrated with the response rate, PFS or OS with bevacizumab treatment. CONCLUSION: Unfortunately, in this histopathological, molecular, immunohistochemical and neuroradiological study we did not find any predictive biomarker of response or survival benefit for Bevacizumab in glioblastoma.

Spiral enteroscopy with the new DSB overtube: a novel technique for deep peroral small-bowel intubation.

BACKGROUND AND STUDY AIMS: Spiral enteroscopy is a new technique for deep small-bowel intubation that uses a special overtube (Discovery Small Bowel, DSB) to pleat small bowel. The aims of this prospective study were to evaluate the use of a new-design DSB over new, longer and smaller-diameter enteroscopes, the Fujinon EN-450T5 and the Olympus SIF-Q180. PATIENTS AND METHODS: This is a prospective study of 75 patients at two referral centers. All enteroscopies were performed by two experienced endoscopists. Patients underwent spiral enteroscopy perorally with the DSB and either the Fujinon EN-450T5 or the Olympus SIF-Q180 enteroscope. Procedure time and depth of insertion past the ligament of Treitz were determined for all patients. RESULTS: Peroral spiral enteroscopy with DSB was performed in 50 patients with the Fujinon enteroscope and in 25 patients with the Olympus. Average estimated depth of insertion was 243 cm (range 50 - 380 cm) vs. 256 cm (range 50 - 400 cm) and the average time to reach this depth was 18.7 minutes (range 7 - 52 minutes) vs. 16.2 minutes (range 7 - 33 minutes) in the Fujinon and the Olympus groups respectively. Overall findings were 10 angiodysplasias, 2 small-bowel tumors, 1 Peutz-Jeghers polyp, 1 case of celiac sprue, 2 of small-bowel strongyloidiasis, and 2 small-bowel ulcers. All angiodysplasias were treated with bipolar cauterization. Biopsies were taken from the small-bowel tumors. There were no major complications. CONCLUSIONS: The new DSB is a means of rapid, safe, and effective deep small-bowel intubation. Depth of insertion into the small bowel and total procedure time compare favorably with other deep enteroscopy techniques. The DSB performed equally well with both enteroscopes.

Toxic effects of dissolved heavy metals on Desulfovibrio vulgaris and Desulfovibrio sp. strains.

Biological treatment of metal-containing wastewaters with sulphate-reducing bacteria (SRB) is an attractive technique for the bioremediation of this kind of medium. In order to design a suitable engineering process to address this environmental problem, it is crucial to understand the inhibitory effect of dissolved heavy metals on these bacteria. Batch studies were carried out to evaluate the toxic effects of several heavy metal ions [Cr(III), Cu(II), Mn(II), Ni(II) and Zn(II)] on two cultures of SRB (Desulfovibrio vulgaris and Desulfovibrio sp.). The experimental data indicate that SRB show different responses to each metal. At the highest metal concentration tolerated for each metal, the precipitation levels for D. vulgaris were as follows: 24.7%-15 ppm Cr(III), 45%-4 ppm Cu(II), 60%-10 ppm Mn(II), 96%-8.5 ppm Ni(II) and 9%-20 ppm Zn(II). The corresponding values for Desulfovibrio sp. were: 25.5%-15 ppm Cr(III), 71%-4 ppm Cu(II), 66.2%-10 ppm Mn(II), 96.1%-8.5 ppm Ni(II) and 93%-20 ppm Zn(II). Results obtained in batch studies will be taken into account for the subsequent design of a sulphate-reducing bioreactor to reduce levels of heavy metals present in different types of contaminated media.

Mathematical model for liquid-gas equilibrium in acetic acid fermentations

An experimental study was conducted to propose an adequate mathematical model for liquid-gas equilibrium in acetic acid fermentations. Three operation scales (laboratory, pilot plant, and industrial plant) were employed to obtain the sets of experimental data. The proposed model, based in the UNIFAC method for the estimation of activity coefficients of a solution consisting of several components, takes into account the effect of temperature. However, in the set of equations, it has been necessary to put in the degree of equilibrium (epsilon). This coefficient adequately reflects the physical conditions of fermentation equipment. The experimental and numerical results help to define the fundamental mechanisms for liquid-gas equilibrium in these systems and demonstrate the model validity in the three tested scales. It was also found that in an industrial setting, closed systems are those with lowest evaporation losses. Copyright 1998 John Wiley & Sons, Inc.

Mathematical model of the oxidation of ferrous iron by a biofilm of Thiobacillus ferrooxidans.

Microbial oxidation of ferrous iron may be a viable alternative method of producing ferric sulfate, which is a reagent used for removal of H(2)S from biogas. The paper introduces a kinetic study of the biological oxidation of ferrous iron by Thiobacillus ferrooxidans immobilized on biomass support particles (BSP) composed of polyurethane foam. On the basis of the data obtained, a mathematical model for the bioreactor was subsequently developed. In the model described here, the microorganisms adhere by reversible physical adsorption to the ferric precipitates that are formed on the BSP. The model can also be considered as an expression for the erosion of microorganisms immobilized due to the agitation of the medium by aeration.

Formation of calcium alginate gel capsules: influence of sodium alginate and CaCl2 concentration on gelation kinetics.

The formation kinetics of calcium alginate gel capsules is studied. An increase in the concentration of alginate gives rise to a reduction in membrane thickness, while an increase in the concentration of calcium chloride leads to the formation of a thicker film. Experimental data are adjusted to the binomial diffusion equation.

Calcium alginate gel as encapsulation matrix for coimmobilized enzyme systems.

Encapsulation within calcium alginate gel capsules was used to produce a coimmobilized enzyme system. Glucose oxidase (GOD) and catalase (CAT) were chosen as model enzymes. The same values of Vmax and Km app for the GOD encapsulated system and for the GOD-CAT coencapsulated system were calculated. When gel beads and capsules were compared, the same catalyst deactivation sequence for the two enzymes was observed. However, when capsules were employed as immobilization support, GOD efficiencies were higher than for the gel beads. These results were explained in terms of the structure of the capsules.

Different strategies for recovering metals from CARON process residue.

The capacity of Acidithiobacillus thiooxidans DMS 11478 to recover the heavy metals contained in the residue obtained from the CARON process has been evaluated. Different bioreactor configurations were studied: a two-stage batch system and two semi-continuous systems (stirred-tank reactor leaching and column leaching). In the two-stage system, 46.8% Co, 36.0% Mg, 26.3% Mn and 22.3% Ni were solubilised after 6h of contact between the residue and the bacteria-free bioacid. The results obtained with the stirred-tank reactor and the column were similar: 50% of the Mg and Co and 40% of the Mn and Ni were solubilised after thirty one days. The operation in the column reactor allowed the solid-liquid ratio to be increased and the pH to be kept at low values (<1.0). Recirculation of the leachate in the column had a positive effect on metal removal; at sixty five days (optimum time) the solubilisation levels were as follows: 86% Co, 83% Mg, 72% Mn and Ni, 62% Fe and 23% Cr. The results corroborate the feasibility of the systems studied for the leaching of metals from CARON process residue and these methodologies can be considered viable for the recovery of valuable metals.

Combined strategy for the precipitation of heavy metals and biodegradation of petroleum in industrial wastewaters.

The precipitation of chromium(III), copper(II), manganese(II) and zinc(II) by biogenic hydrogen sulfide generated by sulfate-reducing bacteria, Desulfovibrio sp., and the degradation of total petroleum hydrocarbons (TPH) in the presence of heavy metal by Pseudomonas aeruginosa AT18 have been carried out. An anaerobic stirred tank reactor was used to generate hydrogen sulfide with Desulfovibrio sp. culture and the precipitation of more than 95% of each metal was achieved in 24 h (metal solutions contained: 60, 49, 50 and 80 mg L(-1) of chromium, copper, manganese and zinc sulfates). A stirred tank reactor with P. aeruginosa AT18, in the presence of the heavy metal solution and 2% (v/v) of petroleum, led to the degradation of 60% of the total petroleum hydrocarbons and the removal of Cr(III) 99%, Cu(II) 93%, Zn(II) 46% and Mn(II) 88% in the medium through biosorption phenomena. These results enabled the development of an integrated system in which the two processes were combined. The overall aim of the study was achieved, with 84% of TPH degraded and all of the metals completely removed. Work is currently underway aimed at improving this system (decrease in operation time, culture of P. aeruginosa in anaerobic conditions) in an effort to apply this process in the bioremediation of natural media contaminated with heavy metals and petroleum.