441 research outputs found

    Elucidating the impact of microbial community biodiversity on pharmaceutical biotransformation during wastewater treatment

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146445/1/mbt212870.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146445/2/mbt212870_am.pd

    Application of several pretreatment technologies to a wastewater effluent of a petrochemical industry finally treated with reverse osmosis

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    [EN] This work studies the adequacy of different reverse osmosis (RO) pretreatments applied to different petrochemical wastewater effluents. Three effluents from a caprolactam factory were analysed: ion-exchange resin washing effluent (RWE), batch reactor washing effluent and factory outlet effluent. Coagulation–flocculation, microfiltration (MF) and ultrafiltration (UF) were tested as RO pretreatments. Various inorganic coagulants (Aluminium Chloride, Iron (III) Chloride, Aluminium Sulphate and polyaluminium chloride), commercial coagulants (Nophos and ACO) and commercial flocculants (polyacrylamide, CH-30 and active polyfloc) were tested at different dosages and stirring speeds. The highest removal of suspended solids (SS) and the lowest turbidity were obtained for the ion-exchange RWE. Two combinations of coagulants and flocculants were chosen as the most suitable conditions for the coagulation–flocculation process. The ion-exchange RWE was further treated with a combination of MF followed by UF. SS were completely removed and turbidity decreased to 0.136 NTU. The silt density index at 15 min was reduced to 6.41.The authors of this work wish to gratefully acknowledge the financial support from the Generalitat Valenciana through the programme “Ayudas para la realizacioÂŽn de proyectos I+D para grupos de investigacioÂŽn emergentes GV/2013”.Vincent Vela, MC.; Alvarez Blanco, S.; Lora GarcĂ­a, J.; Carbonell Alcaina, C.; SĂĄez Muñoz, M. (2014). Application of several pretreatment technologies to a wastewater effluent of a petrochemical industry finally treated with reverse osmosis. Desalination and Water Treatment. 1-9. doi:10.1080/19443994.2014.939866S19Benito-AlcĂĄzar, C., Vincent-Vela, M. C., GozĂĄlvez-Zafrilla, J. M., & Lora-GarcĂ­a, J. (2010). Study of different pretreatments for reverse osmosis reclamation of a petrochemical secondary effluent. Journal of Hazardous Materials, 178(1-3), 883-889. doi:10.1016/j.jhazmat.2010.02.020Madaeni, S. S., & Eslamifard, M. R. (2010). Recycle unit wastewater treatment in petrochemical complex using reverse osmosis process. Journal of Hazardous Materials, 174(1-3), 404-409. doi:10.1016/j.jhazmat.2009.09.067Kim, H.-C., & Dempsey, B. A. (2008). Effects of wastewater effluent organic materials on fouling in ultrafiltration. Water Research, 42(13), 3379-3384. doi:10.1016/j.watres.2008.04.021Karabacakoğlu, B., Tezakıl, F., & GĂŒvenç, A. (2014). Removal of hardness by electrodialysis using homogeneous and heterogeneous ion exchange membranes. Desalination and Water Treatment, 54(1), 8-14. doi:10.1080/19443994.2014.880159Gare, S. (2002). RO systems: the importance of pre-treatment. Filtration & Separation, 39(1), 22-27. doi:10.1016/s0015-1882(02)80047-7Garg, A., Mishra, I. M., & Chand, S. (2010). Effectiveness of coagulation and acid precipitation processes for the pre-treatment of diluted black liquor. Journal of Hazardous Materials, 180(1-3), 158-164. doi:10.1016/j.jhazmat.2010.04.008Verma, S., Prasad, B., & Mishra, I. M. (2010). Pretreatment of petrochemical wastewater by coagulation and flocculation and the sludge characteristics. Journal of Hazardous Materials, 178(1-3), 1055-1064. doi:10.1016/j.jhazmat.2010.02.047Garrote, J. (1995). Treatment of tannery effluents by a two step coagulation/flocculation process. Water Research, 29(11), 2605-2608. doi:10.1016/0043-1354(94)00312-uSanto, C. E., Vilar, V. J. P., Botelho, C. M. S., Bhatnagar, A., Kumar, E., & Boaventura, R. A. R. (2012). Optimization of coagulation–flocculation and flotation parameters for the treatment of a petroleum refinery effluent from a Portuguese plant. Chemical Engineering Journal, 183, 117-123. doi:10.1016/j.cej.2011.12.041Wang, J.-P., Chen, Y.-Z., Wang, Y., Yuan, S.-J., & Yu, H.-Q. (2011). Optimization of the coagulation-flocculation process for pulp mill wastewater treatment using a combination of uniform design and response surface methodology. Water Research, 45(17), 5633-5640. doi:10.1016/j.watres.2011.08.023Rossini, M., Garrido, J. G., & Galluzzo, M. (1999). Optimization of the coagulation–flocculation treatment: influence of rapid mix parameters. Water Research, 33(8), 1817-1826. doi:10.1016/s0043-1354(98)00367-4Guida, M., Mattei, M., Della Rocca, C., Melluso, G., & Meriç, S. (2007). Optimization of alum-coagulation/flocculation for COD and TSS removal from five municipal wastewater. Desalination, 211(1-3), 113-127. doi:10.1016/j.desal.2006.02.086HABERKAMP, J., RUHL, A., ERNST, M., & JEKEL, M. (2007). Impact of coagulation and adsorption on DOC fractions of secondary effluent and resulting fouling behaviour in ultrafiltration. Water Research, 41(17), 3794-3802. doi:10.1016/j.watres.2007.05.029Petrov, S., & Stoichev, P. (2002). Reagent ultrafiltration purification of water contaminated with reactive dyes. Filtration & Separation, 39(8), 35-34. doi:10.1016/s0015-1882(02)80229-4Shon, H. K., Vigneswaran, S., Ngo, H. H., & Ben Aim, R. (2005). Is semi-flocculation effective as pretreatment to ultrafiltration in wastewater treatment? Water Research, 39(1), 147-153. doi:10.1016/j.watres.2004.09.003Hatt, J. W., Germain, E., & Judd, S. J. (2011). Precoagulation-microfiltration for wastewater reuse. Water Research, 45(19), 6471-6478. doi:10.1016/j.watres.2011.09.039Dryden Aqua Ltd, Edinburgh, 2013. Available from: www.DrydenAqua.com (April 6, 2013).Sincero, A. P., & Sincero, G. A. (2002). Physical-Chemical Treatment of Water and Wastewater. doi:10.1201/978142003190

    MAGIC observations of MWC 656, the only known Be/BH system

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    Context: MWC 656 has recently been established as the first observationally detected high-mass X-ray binary system containing a Be star and a black hole (BH). The system has been associated with a gamma-ray flaring event detected by the AGILE satellite in July 2010. Aims: Our aim is to evaluate if the MWC 656 gamma-ray emission extends to very high energy (VHE > 100 GeV) gamma rays. Methods. We have observed MWC 656 with the MAGIC telescopes for ∌\sim23 hours during two observation periods: between May and June 2012 and June 2013. During the last period, observations were performed contemporaneously with X-ray (XMM-Newton) and optical (STELLA) instruments. Results: We have not detected the MWC 656 binary system at TeV energies with the MAGIC Telescopes in either of the two campaigns carried out. Upper limits (ULs) to the integral flux above 300 GeV have been set, as well as differential ULs at a level of ∌\sim5% of the Crab Nebula flux. The results obtained from the MAGIC observations do not support persistent emission of very high energy gamma rays from this system at a level of 2.4% the Crab flux.Comment: Accepted for publication in A&A. 5 pages, 2 figures, 2 table

    The major upgrade of the MAGIC telescopes, Part II: A performance study using observations of the Crab Nebula

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    MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes located in the Canary island of La Palma, Spain. During summer 2011 and 2012 it underwent a series of upgrades, involving the exchange of the MAGIC-I camera and its trigger system, as well as the upgrade of the readout system of both telescopes. We use observations of the Crab Nebula taken at low and medium zenith angles to assess the key performance parameters of the MAGIC stereo system. For low zenith angle observations, the standard trigger threshold of the MAGIC telescopes is ~50GeV. The integral sensitivity for point-like sources with Crab Nebula-like spectrum above 220GeV is (0.66+/-0.03)% of Crab Nebula flux in 50 h of observations. The angular resolution, defined as the sigma of a 2-dimensional Gaussian distribution, at those energies is < 0.07 degree, while the energy resolution is 16%. We also re-evaluate the effect of the systematic uncertainty on the data taken with the MAGIC telescopes after the upgrade. We estimate that the systematic uncertainties can be divided in the following components: < 15% in energy scale, 11-18% in flux normalization and +/-0.15 for the energy spectrum power-law slope.Comment: 21 pages, 25 figures, accepted for publication in Astroparticle Physic

    Limits to dark matter annihilation cross-section from a combined analysis of MAGIC and Fermi-LAT observations of dwarf satellite galaxies

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    We present the first joint analysis of gamma-ray data from the MAGIC Cherenkov telescopes and the Fermi Large Area Telescope (LAT) to search for gamma-ray signals from dark matter annihilation in dwarf satellite galaxies. We combine 158 hours of Segue 1 observations with MAGIC with 6-year observations of 15 dwarf satellite galaxies by the Fermi-LAT. We obtain limits on the annihilation cross-section for dark matter particle masses between 10 GeV and 100 TeV - the widest mass range ever explored by a single gamma-ray analysis. These limits improve on previously published Fermi-LAT and MAGIC results by up to a factor of two at certain masses. Our new inclusive analysis approach is completely generic and can be used to perform a global, sensitivity-optimized dark matter search by combining data from present and future gamma-ray and neutrino detectors.Comment: 19 pages, 3 figures. V2: Few typos corrected and references added. Matches published version JCAP 02 (2016) 03

    Measurement of the Crab Nebula spectrum over three decades in energy with the MAGIC telescopes

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    The MAGIC stereoscopic system collected 69 hours of Crab Nebula data between October 2009 and April 2011. Analysis of this data sample using the latest improvements in the MAGIC stereoscopic software provided an unprecedented precision of spectral and night-by-night light curve determination at gamma rays. We derived a differential spectrum with a single instrument from 50 GeV up to almost 30 TeV with 5 bins per energy decade. At low energies, MAGIC results, combined with Fermi-LAT data, show a flat and broad Inverse Compton peak. The overall fit to the data between 1 GeV and 30 TeV is not well described by a log-parabola function. We find that a modified log-parabola function with an exponent of 2.5 instead of 2 provides a good description of the data (χ2=35/26\chi^2=35/26). Using systematic uncertainties of red the MAGIC and Fermi-LAT measurements we determine the position of the Inverse Compton peak to be at (53 ±\pm 3stat + 31syst -13syst) GeV, which is the most precise estimation up to date and is dominated by the systematic effects. There is no hint of the integral flux variability on daily scales at energies above 300 GeV when systematic uncertainties are included in the flux measurement. We consider three state- of-the-art theoretical models to describe the overall spectral energy distribution of the Crab Nebula. The constant B-field model cannot satisfactorily reproduce the VHE spectral measurements presented in this work, having particular difficulty reproducing the broadness of the observed IC peak. Most probably this implies that the assumption of the homogeneity of the magnetic field inside the nebula is incorrect. On the other hand, the time-dependent 1D spectral model provides a good fit of the new VHE results when considering a 80 {\mu}G magnetic field. However, it fails to match the data when including the morphology of the nebula at lower wavelengths.Comment: accepted by JHEAp, 9 pages, 6 figure

    Detection of bridge emission above 50 GeV from the Crab pulsar with the MAGIC telescopes

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    The Crab pulsar is the only astronomical pulsed source detected at very high energy (VHE, E>100GeV) gamma-rays. The emission mechanism of VHE pulsation is not yet fully understood, although several theoretical models have been proposed. In order to test the new models, we measured the light curve and the spectra of the Crab pulsar with high precision by means of deep observations. We analyzed 135 hours of selected MAGIC data taken between 2009 and 2013 in stereoscopic mode. In order to discuss the spectral shape in connection with lower energies, 4.6 years of {\it Fermi}-LAT data were also analyzed. The known two pulses per period were detected with a significance of 8.0σ8.0 \sigma and 12.6σ12.6 \sigma. In addition, significant emission was found between the two pulses with 6.2σ6.2 \sigma. We discovered the bridge emission above 50 GeV between the two main pulses. This emission can not be explained with the existing theories. These data can be used for testing new theoretical models.Comment: 5 pages, 4 figure

    Multi-Wavelength Observations of the Blazar 1ES 1011+496 in Spring 2008

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    The BL Lac object 1ES 1011+496 was discovered at Very High Energy gamma-rays by MAGIC in spring 2007. Before that the source was little studied in different wavelengths. Therefore a multi-wavelength (MWL) campaign was organized in spring 2008. Along MAGIC, the MWL campaign included the Metsahovi radio observatory, Bell and KVA optical telescopes and the Swift and AGILE satellites. MAGIC observations span from March to May, 2008 for a total of 27.9 hours, of which 19.4 hours remained after quality cuts. The light curve showed no significant variability. The differential VHE spectrum could be described with a power-law function. Both results were similar to those obtained during the discovery. Swift XRT observations revealed an X-ray flare, characterized by a harder when brighter trend, as is typical for high synchrotron peak BL Lac objects (HBL). Strong optical variability was found during the campaign, but no conclusion on the connection between the optical and VHE gamma-ray bands could be drawn. The contemporaneous SED shows a synchrotron dominated source, unlike concluded in previous work based on nonsimultaneous data, and is well described by a standard one zone synchrotron self Compton model. We also performed a study on the source classification. While the optical and X-ray data taken during our campaign show typical characteristics of an HBL, we suggest, based on archival data, that 1ES 1011+496 is actually a borderline case between intermediate and high synchrotron peak frequency BL Lac objects.Comment: 13 pages, accepted for publication in MNRA
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