On the use of the BLYP functional for the DFT calculation of graphite–hydrogen systems

This letter focuses on a possible pitfall that can occur in the DFT calculation of graphite–hydrogen interactions under tokamaks conditions. Calculations based on the BLYP functional, in fact, result in a stable –C₂H₃ group that other functionals (OLYP, XLYP, PBE and BP) do not confirm.     

Existence of Pharmaceutical Compounds in Tertiary Treated Urban Wastewater that is Utilized for Reuse Applications

Research on the effects of chemical pollution in the environment that is related to urban wastewaters?? discharge and reuse until recently was focused almost exclusively on conventional pollutants. During the last several years though there has been a growing level of concern related to the hypothesis that various chemicals may exhibit endocrine disrupting effects. In addition, thousands of tons of pharmacologically active substances are used annually ending up in the wastewaters. In many countries facing prolonged droughts and implementing wastewater reuse schemes for irrigation and groundwater discharge, the existence of xenobiotic compounds in the tertiary treated wastewaters constitutes a new concern. This study describes the application of a recently developed multi-residue method for the determination of 29 multi-class pharmaceuticals using off line solid phase extraction followed by liquid chromatography?Ctriple quadrupole mass spectrometry (LC?CMS?CMS). The method was applied for the analysis of pharmaceutical residues at three sewage treatment plants in Cyprus serving major coastal Mediterranean cities. The presence of 19 pharmaceuticals was confirmed. For some of the compounds high concentrations were obtained for the final effluents (e.g. ofloxacin: 4.82 ??g/L, diclofenac: 5.51 ??g/L, carbamazepine: 27.27 ??g/L, metoprolol: 9.59 ??g/L). Concerning the elimination potential, what was derived from the study is that the biological treatment step contributes the most to the removal of the compounds while sand filtration and chlorination steps reduce slightly the residual concentrations.     

Mineralisation of the antibiotic amoxicillin in pure and surface waters by artificial UVA‐ and sunlight‐induced Fenton oxidation

BACKGROUND: The degradation and mineralisation of the antibiotic amoxicillin by photo‐Fenton reactions, mediated by artificial UVA or solar irradiation, were investigated. Experiments were conducted with 30 mg L^?1 amoxicillin solutions prepared with deionised or surface water at Fe²⁺ and H₂O₂ concentrations in the range 0.0179–0.0895 and 1–10 mmol L^?1, respectively. Black‐light irradiation at 365 nm was provided by a 13 W m^?2 lamp, while samples were exposed to sunlight at 20 W m^?2 for solar experiments. RESULTS: In all cases, quantitative amoxicillin degradation occurred within 5 min and this was accompanied by lower mineralisation rates. Mineralisation followed first‐order kinetics with respect to organic carbon content and it was not affected by the water matrix with either type of illumination. Solar‐induced reactions were only marginally faster than artificial irradiation. Increasing the H₂O₂ to Fe²⁺ concentration ratio increases the extent of mineralisation up to a point beyond which degradation is impeded due to radical scavenging associated with the high concentrations of the Fenton reagents. CONCLUSION: Amoxicillin is readily degradable by homogeneous photocatalysis, being converted to more stable intermediates as indicated by lower mineralisation rates. The process can be driven by solar irradiation, thus providing a sustainable treatment technology. Copyright © 2009 Society of Chemical Industry     

Anaerobic co‐digestion of potato processing wastewater with pig slurry and abattoir wastewater

BACKGROUND: Small‐scale experimental investigations were carried out on the anaerobic digestion of potato processing wastewater and its co‐digestion with pig slurry and/or abattoir wastewater. A simple and rapid procedure was used to determine the suitability of these wastes for digestion. RESULTS: During the initial 5‐day acclimation phase, the seed (digested brewery waste) was replaced by the test waste before allowing the tests to incubate without further addition, where methanogenesis was measured. Although potato processing wastewater has low pH, with high fat content treatment via anaerobic digestion was still feasible in spite of low methane production. Co‐digestion with pig slurry and abattoir wastewater was therefore investigated to enhance the process. Pig slurry improved the process, which, when co‐digested with potato processing wastewater in equal ratio achieved 72% volatile solids removal, 35 mL average daily biogas production and 32% maximum methane content in 22 days (following the acclimation period). Co‐digestion with abattoir wastewater did not improve the digestion process due to poor buffering and low pH value. CONCLUSION: Anaerobic co‐digestion may be a feasible treatment option for industrial bio‐wastes and livestock wastes produced in Cyprus and indeed in similar other countries of comparable market size and activities. Copyright © 2008 Society of Chemical Industry     

Effects of selective water withdrawal schemes on thermal stratification in Kouris Dam in Cyprus

Thermal stratification and its seasonal variations in Kouris Dam in Cyprus were simulated, and the impact of five different water withdrawal schemes was studied, using the 2‐D, laterally averaged CE‐QUAL‐W2 reservoir model. Based on the model simulations, it was found that the thermal stratification of the reservoir is significant for most of the year. Most importantly, a complete mixing of the water column, triggered by seasonal variations in meteorological conditions, occurs in late‐January. Predicted thermal stratification and water temperature profiles in the reservoir are noticeably affected by water withdrawal schemes. It was found that deep‐water withdrawals tend to facilitate heat transfer in the water column and deepen the water mixing layer (epilimnion), especially from September to the following January. These study results suggest that it is prudent for Kouris Dam to integrate selective water withdrawal schemes into reservoir management by using the water withdrawal effects on thermal stratification for different water quality management strategies.     

Direct numerical simulation of turbulent liquid metal flow entering a magnetic field

This paper presents direct numerical simulations (DNS) of fully developed turbulent liquid-metal flow in a circular duct entering a magnetic field. The case of a magnetohydrodynamic flow leaving a strong magnetic field has been extensively studied experimentally and numerically owing to its similarity to typical flow configurations appearing in liquid metal blankets of nuclear fusion reactors. Although also relevant to the design of fusion reactor blankets, the flow entering the fringing field of a magnet remains unexplored because its high intricacy precludes any simplification of the governing equations. Indeed, the complexity of the magnetohydrodynamic–turbulence interaction can only be analysed by direct numerical simulations or experiments. With that purpose, this paper addresses the case of a fully developed turbulent flow (Re_τ ≈ 520) entering low, intermediate and strong magnetic fields under electrically insulating and poorly conducting walls by means of three-dimensional direct numerical simulations. Purely hydrodynamic computations (without the effect of the magnetic field) reveal an excellent agreement against previous experimental and numerical results. Current MHD results provide a very detailed information of the turbulence decay and reveal new three-dimensional features related to liquid-metal flow entering strong increasing magnetic fields, such as flow instabilities due to the effect of the Lorentz forces within the fringing region at high Ha numbers.