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1.
Phys Rev Lett ; 130(15): 153201, 2023 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-37115860

RESUMEN

We report a combined experimental and theoretical study on the effect of autoionizing resonances in time-resolved photoelectron spectroscopy. The coherent excitation of N_{2} by ∼14.15 eV extreme-ultraviolet photons prepares a superposition of three dominant adjacent vibrational levels (v^{'}=14-16) in the valence b^{'} ^{1}Σ_{u}^{+} state, which are probed by the absorption of two or three near-infrared photons (800 nm). The superposition manifests itself as coherent oscillations in the measured photoelectron spectra. A quantum-mechanical simulation confirms that two autoionizing Rydberg states converging to the excited A ^{2}Π_{u} and B ^{2}Σ_{u}^{+} N_{2}^{+} cores are accessed by the resonant absorption of near-infrared photons. We show that these resonances apply different filters to the observation of the vibrational wave packet, which results in different phases and amplitudes of the oscillating photoelectron signal depending on the nature of the autoionizing resonance. This work clarifies the importance of resonances in time-resolved photoelectron spectroscopy and particularly reveals the phase of vibrational quantum beats as a powerful observable for characterizing the properties of such resonances.

2.
J Environ Manage ; 329: 117078, 2023 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-36571949

RESUMEN

Membrane capacitive deionization (MCDI) has shown many advances, however, its performance in combination with other treatment technologies has not been widely reported. In this study, a pilot-scale low-pressure reverse osmosis (LPRO) (FilmTec™ XLE-2540) with MCDI (CapDI© C17, Voltea) was developed and tested as a promising modular desalination system. The systems were evaluated individually at different salinities and tested together as a modular system. The study focused in the comparison to conventional seawater reverse osmosis (SWRO) (FilmTec™ SW30-2540) at pilot-scale and in theory using the software Water Application Value Engine (WAVE, DuPont™), including a cost evaluation of the systems. Pilot tests were carried out in Can Gio, a riverine estuary region in South Vietnam, which is affected by progressive salinization (TDS ≈ 1-25 g/L). Drinking water quality (TDS < 600 mg/L) was achieved with a specific energy consumption (SEC) of 5.2 kWh/m³. Additionally, fouling mitigation was investigated for the ultrafiltration (UF) pre-treatment by periodic hydraulic and chemical enhanced backwashing. While the SWRO had a slightly lower SEC of 5.0 kWh/m³, WAVE calculations showed that lowering the SEC to 3.6 kWh/m³ is possible by improving the LPRO pump design and an optimization of the MCDI operation.


Asunto(s)
Purificación del Agua , Vietnam , Ósmosis , Membranas Artificiales , Agua de Mar
3.
Opt Express ; 30(13): 22376-22387, 2022 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-36224936

RESUMEN

We present the energy scaling of a sub-two-cycle (10.4 fs) carrier-envelope-phase-stable light source centered at 1.76 µm to 1.9 mJ pulse energy. The light source is based on an optimized spectral-broadening scheme in a hollow-core fiber and a consecutive pulse compression with bulk material. This is, to our knowledge, the highest pulse energy reported to date from this type of sources. We demonstrate the application of this improved source to the generation of bright water-window soft-X-ray high harmonics. Combined with the short pulse duration, this source paves the way to the attosecond time-resolved water-window spectroscopy of complex molecules in aqueous solutions.

4.
Phys Rev Lett ; 128(13): 133001, 2022 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-35426704

RESUMEN

We report the first observation of intermolecular Coulombic decay (ICD) in liquid water following inner-valence ionization. By combining a monochromatized tabletop high-harmonic source with a liquid microjet, we record electron-electron coincidence spectra at two photon energies that identify the ICD electrons, together with the photoelectrons originating from the 2a_{1} inner-valence band of liquid water. Our results confirm the importance of ICD as a source of low-energy electrons in bulk liquid water and provide quantitative results for modeling the velocity distribution of the slow electrons that are thought to dominate radiation damage in aqueous environments.

5.
Opt Express ; 29(19): 30799-30808, 2021 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-34614799

RESUMEN

Laboratory-based coherent light sources enable a wide range of applications to investigate dynamical processes in matter. High-harmonic generation (HHG) from liquid samples is a recently discovered coherent source of extreme-ultraviolet (XUV) radiation potentially capable of achieving few-femtosecond to attosecond pulse durations. However, the polarization state of this light source has so far remained unknown. In this work, we characterize the degree of polarization of both low- and high-order harmonics generated from liquid samples using linearly polarized 400 nm and 800 nm drivers. We find a remarkably high degree of linear polarization of harmonics ranging all the way from the deep-ultraviolet (160 nm) across the vacuum-ultraviolet into the XUV domain (73 nm). These results establish high-harmonic generation in liquids as a promising alternative to conventional sources of XUV radiation, combining the benefits of high target densities comparable to solids with a continuous sample renewal that avoids the limitations imposed by laser-induced damage.

6.
J Environ Manage ; 297: 113409, 2021 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-34346395

RESUMEN

Landfill leachate contains many complex components that have a negative impact on the environment when improperly discharged. This study is the first to treat landfill leachate (after continuous flow sequencing bed biofilm reactor (CF-SBBR) bio-digested) using electrocoagulation (EC) combined with persulfate (PS) on Al and Fe electrodes. The effect of some of the key parameters on the COD, Color, TOC and TN removal efficiencies as part of the EC-PS process were studied using the PS concentration, reaction time, initial pH, current density, and aeration rate. The results show that a PS concentration of 3 g/L improved the COD removal efficiency by 9.0 ± 1.3 % at the Al electrode and 16.0 ± 2.6 % at the Fe electrode. Aeration also improved the COD, TOC and color removal efficiencies by about 10.0 ± 2.3 %, 8.0 ± 1.7 % and 3.0 ± 0.5 % at an optimal aeration rate 3.3 L/min. The optimal operation conditions for the EC-PS process were a PS concentration of 3 g/L, a pH of 2.0 (Al electrode), a pH of 4.0 (Fe electrode), a reaction time of 70 min, a current density of 35 mA/cm2 and an aeration rate of 3.3 L/min. The highest COD, color, TOC and TN removal efficiencies were 46.5 ± 1.8 %, 95.8 ± 2.4 %, 83.5 ± 1.7 %, and 40.9 ± 1.6 % at Al electrode and 54.4 ± 2.3 %, 98.5 ± 2.1 %, 78.6 ± 1.5 % and 57.9 ± 1.1 % at the Fe electrode. The EC-PS working mechanisms involve co-precipitation, an advanced oxidation process (AOPs) using oxidation radicals (HO, SO4-) and flotation. EC-PS is a promising method to treat bio-digested landfill leachate.


Asunto(s)
Contaminantes Químicos del Agua , Biopelículas , Electrocoagulación , Electrodos , Oxidación-Reducción , Contaminantes Químicos del Agua/análisis
7.
Water Sci Technol ; 80(7): 1326-1337, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31850884

RESUMEN

Tannery wastewater is known to contain high concentrations of organic compounds, heavy metals, nitrogen, sulphur, chromium, and many other chemicals. Both aerobic and anaerobic biological approaches have proven ineffective in the treatment of tannery wastewater due to the high salinity and toxic chemicals contained within the medium. Electrochemical oxidation presents a promising method for solving this problem. High pollutant removal efficiency, low energy consumption, and high electrode stability are three important factors supporting the feasibility of an efficient electrochemical treatment process. In the present study, electrochemical oxidation was performed as a post treatment for tannery wastewater (after biological pre-treatment) in a batch reactor using Ti/RuO2, Ti/IrO2, and Ti/BDD anodes. The effects of pH, current density, stirring rate and treatment time were studied to assess the treatment efficiency as well as the energy consumption of the process. The results showed that colour, chemical oxygen demand (COD), total organic carbon (TOC), and total nitrogen (TN) removal efficiencies on the electrodes were: Ti/RuO2 (88.8%, 88.40%, 64.0%, 96.4%), Ti/IrO2 (85.40%, 85.9%, 52.3%, 51.4%), Ti/BDD (90.60%, 94.7%, 90.5%, 82.7%) respectively, at a current density of 80 mA/cm2. All three electrodes demonstrated optimal performance at a pH of 8, a stirring rate of 400 rpm, a current density of 80 mA/cm2, and an electrolysis time of 5 h. The concentration of tri-chloromethane by-product was detected with limiting value. Electrochemical oxidation thus offers a feasible method for removing organic compounds and nutrients from tannery wastewater.


Asunto(s)
Aguas Residuales , Contaminantes Químicos del Agua , Análisis de la Demanda Biológica de Oxígeno , Electrodos , Electrólisis , Oxidación-Reducción
8.
Opt Lett ; 43(8): 1790-1793, 2018 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-29652365

RESUMEN

Coherent extreme ultraviolet (EUV) radiation using high-harmonic generation (HHG) in α-quartz is demonstrated from 10 to 200 kHz, using 50 fs laser pulses at the center wavelength of 1030 nm. The EUV radiation extends beyond 25 eV in the nondamaging regime. The number of photons generated in a single harmonic order at 15.6 eV is measured to be ≈(3.5±2.5)×1010 per second which, to the best of our knowledge, is a first and record value reported to date using EUV HHG from solids. This Letter demonstrates one of the first all-solid-state EUV sources based on industrial-grade fiber lasers, enabling the possibility of bringing reliable EUV sources to the mass market.

9.
J Oncol Pharm Pract ; 22(2): 228-34, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25471252

RESUMEN

BACKGROUND: Invasive fungal infections remain problematic in immunosuppressed allogeneic stem cell transplant recipients and the use of corticosteroids for the treatment of graft-versus-host-disease can increase the risk threefold. Although antifungal prophylaxis has been shown to decrease the incidence of infection, the optimal antifungal prophylactic regimen in this patient population has yet to be identified.Since early diagnosis of fungal infections might not be possible and the treatment of established fungal infections might be difficult and associated with high infection-related mortality, prevention has become an important strategy in reducing overall morbidity and mortality. While triazoles are the preferred agents, some patients are unable to tolerate them and an alternative drug is warranted. OBJECTIVES: To assess the tolerability of once weekly liposomal amphotericin B as a prophylactic strategy in patients undergoing stem cell transplantation by evaluating any adverse events leading to its discontinuation. In terms of efficacy, to also compare the outcome and incidence of invasive fungal infections in patients who received amphotericin B, triazoles, and echinocandins. RESULTS: A total of 101 allogeneic transplant recipients receiving corticosteroids for the treatment of graft-versus-host-disease and antifungal prophylaxis were evaluated from August 2009 to September 2012. Liposomal amphotericin B 3 mg/kg intravenous once weekly was found to be well tolerated. The incidence of invasive fungal infections was 19%, 17%, and 7% in the liposomal amphotericin B, echinocandin, and triazole groups, respectively. Two deaths occurred in the liposomal amphotericin B group and one death occurred in the echinocandin group. None of the deaths were fungal infection related. CONCLUSION: Antifungal prophylaxis with liposomal amphotericin B was well tolerated, but the incidence of invasive fungal infections in patients receiving liposomal amphotericin B was higher than other antifungal agents in this study. The optimal dose and schedule of liposomal amphotericin B for antifungal prophylaxis in this patient population are still not known and considering its broad spectrum activity, prospective trials in comparison to triazoles are warranted.


Asunto(s)
Anfotericina B/administración & dosificación , Antifúngicos/administración & dosificación , Enfermedad Injerto contra Huésped/tratamiento farmacológico , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Infecciones Fúngicas Invasoras/prevención & control , Adulto , Anfotericina B/efectos adversos , Antifúngicos/efectos adversos , Esquema de Medicación , Femenino , Enfermedad Injerto contra Huésped/diagnóstico , Enfermedad Injerto contra Huésped/epidemiología , Humanos , Infecciones Fúngicas Invasoras/diagnóstico , Infecciones Fúngicas Invasoras/epidemiología , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Estudios Retrospectivos , Trasplante Homólogo , Resultado del Tratamiento
10.
Sci Adv ; 10(13): eadl3810, 2024 Mar 29.
Artículo en Inglés | MEDLINE | ID: mdl-38536928

RESUMEN

We experimentally and theoretically demonstrate that electron correlation can cause the bond-length sensitivity of a shape resonance to induce an unexpected vibrational state-dependent ionization delay in a nonresonant channel. This discovery was enabled by a high-resolution attosecond-interferometry experiment based on a 400-nm driving and dressing wavelength. The short-wavelength driver results in a 6.2-electron volt separation between harmonics, markedly reducing the spectral overlap in the measured interferogram. We demonstrate the promise of this method on O2, a system characterized by broad vibrational progressions and a dense photoelectron spectrum. We measure a 40-attosecond variation of the photoionization delays over the X2Πg vibrational progression. Multichannel calculations show that this variation originates from a strong bond-length dependence of the energetic position of a shape resonance in the [Formula: see text] channel, which translates to the observed effects through electron correlation. The unprecedented energy resolution and delay accuracies demonstrate the promise of visible-light-driven molecular attosecond interferometry.

11.
Heliyon ; 10(5): e26783, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38434284

RESUMEN

In this study, we investigated the possibility of a photocatalytic system that uses graphene-quantum-dot (GQD)-deposited graphitic carbon nitride (g-C3N4) to treat tetracycline (TC) and other organic compounds generated from an in-situ-recirculatory-aquaculture-system (RAS)-like shrimp farming pond. GQDs were successfully deposited on the exfoliated g-C3N4 base through a hydrothermal treatment. The results showed that the incorporation of GQDs into the g-C3N4 enhanced its porosity without aggregating its mesoporous structure. The GQDs-deposited g-C3N4 photocatalysts revealed sheet-like structures with nanopores on their surface that facilitate photocatalysis. More than 90% of the TC was removed by the photocatalysts under UV-LED irradiation. Low loadings of GQDs over g-C3N4 resulted in a faster and more effective photocatalysis of TC, mainly driven by.O2- radicals. The photocatalysts were also applicable in the degradation of organic compounds with 27% of the total organic compounds (TOC) being removed from the wastewater of a RAS-like shrimp farming pond.

12.
Sci Total Environ ; 860: 160366, 2023 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-36471521

RESUMEN

Textile wastewater contains many organic compounds and colors that affect aquatic life and human health when discharged into the environment. High coloration due to excess dyes entering the wastewater causes coloration to the receiving water stream, affects the photosynthesis process of aquatic species, and adversely affects the landscape. SnO2-based electrodes have been extensively used in electrochemical water treatment, but their low durability decreases the pollutant treatment ability. Therefore, it is necessary to add another stable oxide to improve the performance and stability of SnO2 electrodes. This study aims to fabricate Ti/SnO2-Nb2O5 electrodes for the textile wastewater treatment using the electrochemical oxidation method. Different molar ratios of SnO2:Nb2O5 coating were prepared using the sol-gel method and then coated on the Ti substrates for calcination in 60 min at 500 °C. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET), and cyclic voltammetry (CV) were used to determine the surface and electrochemical properties of Ti/SnO2-Nb2O5 electrodes. The SEM images show that SnO2-Nb2O5 electrode surfaces have the appearance of typical cracking structures of mixed metal oxides electrodes. The XRD spectrum show the SnO2 peaks of facet (110), (101), (200), (301), (321) and Nb2O5 peaks of facet (001), (002), (100), (101), (102) on Ti substrates. Furthermore, the specific surface area of the Ti/SnO2-Nb2O5 electrode ranges from 37.354 m2/g (SnO2:Nb2O5 = 9:1) to 71.885 m2/g (SnO2:Nb2O5 = 1:9). The electrochemical properties of SnO2:Nb2O5 electrodes showed high oxygen, chlorine evolution potential and high organic pollutant degradation in textile wastewater with COD removal at 83 %, decolorization at 74 % and the generation of many free radicals such as HO•, H2O2, O3, Cl2. The results demonstrate that the Ti/SnO2-Nb2O5 electrode with the mole ratio of 3:7 is the best in textile wastewater treatment with the longest service life (39 h).


Asunto(s)
Contaminantes Químicos del Agua , Purificación del Agua , Humanos , Aguas Residuales , Titanio/química , Peróxido de Hidrógeno , Compuestos de Estaño , Contaminantes Químicos del Agua/química , Niobio , Oxidación-Reducción , Óxidos , Electrodos , Purificación del Agua/métodos
13.
Sci Rep ; 13(1): 3059, 2023 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-36810355

RESUMEN

We present an apparatus for attosecond transient-absorption spectroscopy (ATAS) featuring soft-X-ray (SXR) supercontinua that extend beyond 450 eV. This instrument combines an attosecond table-top high-harmonic light source with mid-infrared (mid-IR) pulses, both driven by 1.7-1.9 mJ, sub-11 fs pulses centered at 1.76 [Formula: see text]m. A remarkably low timing jitter of [Formula: see text] 20 as is achieved through active stabilization of the pump and probe arms of the instrument. A temporal resolution of better than 400 as is demonstrated through ATAS measurements at the argon L[Formula: see text]-edges. A spectral resolving power of 1490 is demonstrated through simultaneous absorption measurements at the sulfur L[Formula: see text]- and carbon K-edges of OCS. Coupled with its high SXR photon flux, this instrument paves the way to attosecond time-resolved spectroscopy of organic molecules in the gas phase or in aqueous solutions, as well as thin films of advanced materials. Such measurements will advance the studies of complex systems to the electronic time scale.

14.
J Control Release ; 356: 232-241, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36878319

RESUMEN

Peptide cancer vaccines have had limited clinical success despite their safety, characterization and production advantages. We hypothesize that the poor immunogenicity of peptides can be surmounted by delivery vehicles that overcome the systemic, cellular and intracellular drug delivery barriers faced by peptides. Here, we introduce Man-VIPER, a self-assembling (40-50 nm micelles), pH-sensitive, mannosylated polymeric peptide delivery platform that targets dendritic cells in the lymph nodes, encapsulates peptide antigens at physiological pH, and facilitates endosomal release of antigens at acidic endosomal pH through a conjugated membranolytic peptide melittin. We used d-melittin to improve the safety profile of the formulation without compromising the lytic properties. We evaluated polymers with both releasable (Man-VIPER-R) or non-releasable (Man-VIPER-NR) d-melittin. Both Man-VIPER polymers exhibited superior endosomolysis and antigen cross-presentation compared to non-membranolytic d-melittin-free analogues (Man-AP) in vitro. In vivo, Man-VIPER polymers demonstrated an adjuvanting effect, induced the proliferation of antigen-specific cytotoxic T cells and helper T cells compared to free peptides and Man-AP. Remarkably, antigen delivery with Man-VIPER-NR generated significantly more antigen-specific cytotoxic T cells than Man-VIPER-R in vivo. As our candidate for a therapeutic vaccine, Man-VIPER-NR exerted superior efficacy in a B16F10-OVA tumor model. These results highlight Man-VIPER-NR as a safe and powerful peptide cancer vaccine platform for cancer immunotherapy.


Asunto(s)
Vacunas contra el Cáncer , Neoplasias , Humanos , Polímeros/química , Antígenos , Péptidos/farmacología , Sistemas de Liberación de Medicamentos , Presentación de Antígeno , Neoplasias/terapia , Células Dendríticas
15.
Nat Commun ; 14(1): 2328, 2023 Apr 22.
Artículo en Inglés | MEDLINE | ID: mdl-37087465

RESUMEN

High-harmonic radiation can be generated when an ultra-intense laser beam is reflected from an over-dense plasma, known as a plasma mirror. It is considered a promising technique for generating intense attosecond pulses in the extreme ultraviolet and X-ray wavelength ranges. However, a solid target used for the formation of the over-dense plasma is completely damaged by the interaction. Thus, it is challenging to use a solid target for applications such as time-resolved studies and attosecond streaking experiments that require a large amount of data. Here we demonstrate that high-harmonic radiation can be continuously generated from a liquid plasma mirror in both the coherent wake emission and relativistic oscillating mirror regimes. These results will pave the way for the development of bright, stable, and high-repetition-rate attosecond light sources, which can greatly benefit the study of ultrafast laser-matter interactions.

16.
Nat Chem ; 14(10): 1126-1132, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35953643

RESUMEN

Directly contrasting ultrafast excited-state dynamics in the gas and liquid phases is crucial to understanding the influence of complex environments. Previous studies have often relied on different spectroscopic observables, rendering direct comparisons challenging. Here, we apply extreme-ultraviolet time-resolved photoelectron spectroscopy to both gaseous and liquid cis-stilbene, revealing the coupled electronic and nuclear dynamics that underlie its isomerization. Our measurements track the excited-state wave packets from excitation along the complete reaction path to the final products. We observe coherent excited-state vibrational dynamics in both phases of matter that persist to the final products, enabling the characterization of the branching space of the S1-S0 conical intersection. We observe a systematic lengthening of the relaxation timescales in the liquid phase and a red shift of the measured excited-state frequencies that is most pronounced for the complex reaction coordinate. These results characterize in detail the influence of the liquid environment on both electronic and structural dynamics during a complete photochemical transformation.

17.
Sci Total Environ ; 787: 147680, 2021 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-34004532

RESUMEN

Landfill leachate contains many pollutants that have a negative effect on the environment when improperly discharged. Thus the treatment of landfill leachate is a crucial issue, especially in the bigger cities in developing countries. In this study, landfill leachate is treated using a continuous flow sequencing biofilm batch reactor (CF-SBBR) with different biocarriers (non-carrier (NC), kaldness K1 (K1), mutag biochip 30™ (MB), and sponge polyurethane (SP)). The results show that the best COD, TOC, and NH4+-N removal efficiencies were 79.6 ± 0.8%, 78.1 ± 1.9% and 77.5 ± 3.9% in the MB biocarriers tank with an aeration/mixing ratio of 1.3, a cycle time of 9 h and an organic loading rate (OLR) of 1.74 kgCOD/m3.d. The TN removal efficiencies was decreased when there was an increase in the biocarrier's surface area (NC > K1 > MB > SP). At the highest it was 46.1 ± 6.4%, where the aeration/mixing ratio was 1.3, the cycle time was 9 h, and the OLR was 1.52 kgCOD/m3.d. The higher the surface area of the biocarriers, the greater the anti-shock organic loading capacity of the biocarriers due to the formation of biofilm layers. The microbial communities in the CF-SBBR tanks were abundant with common phylum bacteria as in a conventional activated sludge system. Anammox candidatus bacteria was found to total 0.5%. This study concluded that CF-SBBR is an efficient method to treat landfill leachate.


Asunto(s)
Contaminantes Químicos del Agua , Biopelículas , Reactores Biológicos , Nitrógeno , Eliminación de Residuos Líquidos
18.
Opt Express ; 18(25): 26365-72, 2010 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-21164987

RESUMEN

The long-term carrier-envelope phase (CEP) coherence of a femtosecond laser with same pulse-to-pulse CEP value, obtained using the direct locking method, is demonstrated by employing a quasi-common-path interferometer (QPI). For the evaluation of the CEP stability, the phase noise properties of a femtosecond laser with the CEP stabilized using a QPI are compared with those obtained using a Mach-Zehnder f-2f interferometer, for which the phase power spectral density and the Allan deviation were calculated from the beat signals of the interferometers. With the improved CEP stability, the long-term CEP coherent signal with an accumulated phase noise well below 1 radian can be maintained for more than 56 hours, i.e., the CEP coherence is preserved without a phase cycle slip for more than 1.6 × 10(13) pulses at a repetition rate of 80 MHz. The relative stability is also estimated to be approximately 1.4 × 10(-22) at a central wavelength of 790 nm.


Asunto(s)
Interferometría/instrumentación , Rayos Láser , Diseño Asistido por Computadora , Diseño de Equipo , Análisis de Falla de Equipo , Retroalimentación
19.
Front Microbiol ; 11: 576438, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33178157

RESUMEN

Swine wastewater contains high concentrations of organic compounds, nutrients (nitrogen and phosphorus), heavy metals, and residual antibiotics, amongst others, that have negative impacts on the water environment. The main aim of this work was to remove nutrients from anaerobically digested swine wastewater using an intermittent cycle extended aeration system (ICEAS). The effects of operational parameters such as cycle time, organic loading rate, C/N ratio, and aeration/mixing ratio on the pollutant removal efficiencies of ICEAS were studied and compared with the performance of a conventional sequencing batch reactor (SBR). The following optimal conditions were obtained: cycle time, 6 h; organic loading rate, 0.86 kg COD m-3 day-1; C/N ratio, 2.49-2.82; and aeration/mixing ratio, 1.57. The pH was maintained in the range of 6.0-8.0. The total organic carbon (TOC), total nitrogen (TN), ammonium (NH4 +), total phosphorus (TP), and color removal efficiencies of ICEAS were higher than those of the conventional SBR, with removal efficiencies of 95.22, 88.29, 97.69, 85.81, and 97.84%, respectively, compared to 94.34, 81.16, 94.15, 77.94, and 96.95%, respectively, observed in the SBR. TOC, TN, NH4 +, TP, and the color removal efficiencies of ICEAS were higher by 0.88, 7.13, 3.54, 7.87, and 0.95%, respectively, than the conventional SBR. The good results from this study show that ICEAS is a promising technology for the removal of organic contaminants and nutrients from anaerobically digested swine wastewater and that the effluent water quality meets the Vietnamese discharge standard (QCVN 62-MT:2016/BTNMT) for swine wastewater effluents.

20.
Water Res ; 181: 115929, 2020 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-32505884

RESUMEN

The principle of subsurface arsenic removal (SAR) from groundwater is based on oxidation and adsorption reactions by infiltrating oxygen into the anoxic aquifer and the immobilization of arsenic (As) onto freshly formed iron (Fe)-(hydr)oxides. In this study, a pilot-scale plant for SAR has been subject to long term testing in the Mekong Delta, Vietnam. Initial concentrations of Fe (8.4 ± 1.3 mg L-1) and As (81 ± 8 µg L-1) in the exploited groundwater were successfully lowered to below the WHO guideline value limits for drinking water of 0.3 mg L-1 and 10 µg L-1, respectively. Adsorption and co-precipitation of As with Fe-(hydr)oxides could be identified as the principal mechanism responsible for the As removal from groundwater, demonstrating the feasibility of SAR as a low-cost and zero-waste solution over a period of two years. However, naturally occurring geochemical reducing conditions and high ammonium levels in the groundwater delayed the removal of manganese (Mn). An additional post-treatment filtration for Mn-removal was temporarily used to comply with the Vietnamese drinking water standard until a Mn-mitigation was achieved by the SAR process. In contrast to most As-remediation technologies, SAR appears to be a long-term, sustainable treatment option with the salient advantage of negligible production of toxic waste, which with ex-situ processes require additionally management costs.


Asunto(s)
Arsénico , Agua Subterránea , Contaminantes Químicos del Agua , Purificación del Agua , Hierro , Vietnam
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