High H2S concentrations abatement in a biotrickling filter: start-up at controlled pH and effect of the EBRT and O2H2S supply ratio

[Abstract] In this study, a biotrickling filter reactor was set up and used to treat high concentrations of gaseous H2S. Inoculation was carried out at an inlet H2S concentration of 1,000 ppmv (27.8 g H2S m-3 h-1) and sludge from a municipal wastewater treatment plant (MWWTP) was used as inoculum. After 3 days, removal efficiency (RE) above 98 % was achieved even after the loading rate (LR) was increased up to 55.6 g H2S m-3 h-1 (2,000 ppmv). Operation at such LR, with an empty bed residence time (EBRT) of 180 s and controlled pH of 6.5-7 was carried out during 3 months. The start-up phase, the effect of decreasing EBRTs at constant inlet concentration and the composition of the process end-products in relation to the supplied O2/H2S ratio were studied. Also, a carbon mass balance under steady state conditions was calculate

Performance of an industrial biofilter from a composting plant in the removal of ammonia and VOCs after material replacement

BACKGROUND: Biofiltration is a suitable odor reduction technique for the treatment of gaseous emissions from composting processes, but little is known about the start-up of full-scale biofilters after material replacement and their performance after several years of operation. - RESULTS: Biofilter material (wood chips used previously as bulking agent in a composting process) can effectively remove ammonia and most of the volatile organic compounds (VOCs) content, achieving removal efficiencies greater than 70% for VOCs and near 90% for ammonia immediately after material replacement. These removal efficiencies were maintained for several months after material replacement. In the studied full-scale biofilter no lag phase was observed in the removal of ammonia whereas in the case of VOCs different patterns were detected during biofilter start-up. For the old biofilter material, after 4 years of operation, a statistically significant decrease of removal efficiency for ammonia in comparison with the new material was detected. No statistically significant differences were found in the case of VOCs. - CONCLUSIONS: Data on the emissions of several pollutants from biofilters treating composting exhaust gases have been systematically obtained. The tested filtering media presented adequate properties for biofiltration of gases emitted during the composting process

Mesurer l’insolvabilité ?

Cet article vise à relier les connaissances de l’histoire du droit sur les procédures de règlement judiciaire de l’insolvabilité aux problématiques classiques de l’histoire économique, en particulier à l’usage des faillites comme indicateur de conjoncture. Nous montrons que le dénombrement des dépôts de bilan n’est pas suffisant pour construire un indicateur de conjoncture. Il faut, pour aller plus loin, prendre en compte les multiples voies procédurales existantes au xviiie  siècle. Cette approche permet d’affiner l’interprétation des crises économiques et renouvelle la question de la distribution des faillites selon le secteur d’activité.This paper aims to link the history of law’s knowledges about judicial procedures for insolvency solving with  classical questions in economic history, particularly the use of failures as a conjuncture indicator. We state that the numbering of dépôts de bilans is not sufficient to build a conjuncture indicator. It is necessary to take in consideration the multiple procedures available in the 18th century. This could allow a better understanding of economic crises and renew the question of failures’ professional distribution

Colaniella, a late Permian Tethyan foraminifera: proposals for a simplified taxonomy, geographical distribution and environments,Colaniella, foraminifere index du Permien tardif tethysien: propositions pour une taxonomie simplifiee, repartition geographique et environnements

A simplified taxonomic classification in 3 groups of the genus Colaniella Likharev is proposed: Colaniella ex gr. parva. Colaniella ex gr. lepida. Colaniella ex gr. minima. The repartition of the eight main Colaniella biofacies is given and the paleogeographic distribution of this genus is presented on a late Permian map configuration

Composition dependence of lithium diffusion in lithium silicide: a density functional theory study

The lithiation process of silicon was investigated by using ab initio molecular dynamics. Diffusion coefficients of Li in Li–Si alloys were calculated to be in the range between 2.08×10−9 and 3.53×10−7 cm2 s−1 at room temperature. The results showed that the Li mobility is strongly dependent on the composition of the LixSi alloys. The Li diffusivity in a LixSi alloy can be enhanced by two orders of magnitude when x is increased from 1.0 to 3.75, which can be explained by the instability of the Si network, owing to charge transfer from Li to Si

High H2S concentration abatement in a biotrickling filter: start-up at controlled pH and effect of the EBRT on O2/H2S supply ratio

In this study, a biotrickling filter reactor was set up and used to treat high concentrations of gaseousH2S. Inoculation was carried out at an inlet H2S concentration of 1,000 ppmv (27.8 g H2S m-3 h-1)and sludge from a municipal wastewater treatment plant (MWWTP) was used as inoculum. After 3days, removal efficiency (RE) above 98 % was achieved even after the loading rate (LR) wasincreased up to 55.6 g H2S m-3 h-1 (2,000 ppmv). Operation at such LR, with an empty bed residencetime (EBRT) of 180 s and controlled pH of 6.5-7 was carried out during 3 months. The start-upphase, the effect of decreasing EBRTs at constant inlet concentration and the composition of theprocess end-products in relation to the supplied O2/H2S ratio were studied. Also, a carbon massbalance under steady state conditions was calculated.Peer ReviewedPostprint (published version

Hydrophobic air pollutants removal at one second gas contact in a multi-channel capillary bioreactor

Producción CientíficaBiological processes are increasingly applied for gas purification as a sustainable and economical alternative to conventional physical-chemical processes (chemical absorption, incineration, adsorption). Although biological gas treatment is accepted as an economical, safe, and reliable air pollution control technology, it faces important limitations when applied for the treatment of poorly water-soluble compounds due to mass transfer limitations. A twenty-five capillary channels bioreactor was studied to characterize mass transfer coefficients and the removal of hydrophobic air pollutants under segmented gas-liquid flow pattern. The removal efficiency of hexane, toluene and α-pinene vapors reached values up to about 75%, 99% and 75%, respectively, at a gas contact time of less than 1 second, which is at least one, but closer to two orders of magnitude shorter than conventional biological gas purification systems. The bioreactor displayed stable operation for 100 days and was robust against common upsets, which opens the new opportunities for expanding the application field of biological processes for air pollution control and the mitigation of greenhouse gases in dilute air streams.Ministerio de Ciencia e Innovación y Ministerio de Universidades [project RTI2018-0-096441-B-I00]Junta de Castilla y León - EU-FEDER [grant number CLU 2017-09 y CL-EI-2021-07