Ammonia removal in anaerobic digestion by biogas stripping: an evaluation of process alternatives using a first order rate model based on experimental findings

The feasibility of biogas stripping to remove ammonia in the anaerobic digestion of source segregated food waste was investigated. It was found in batch experiments that ammonia could be removed from digestate and that the removal followed 1st order kinetics with respect to total ammonia nitrogen concentration. Increasing temperature, biogas flow rate and initial pH all increased removal rates. Using kinetic data gathered in these experiments allowed the integration of ammonia stripping with an anaerobic digestion plant to be modelled for different configurations. Four scenarios were identified: post digestion, in situ, side-stream and pre-digestion ammonia removal relating to where in the process the ammonia stripping was performed. The modelling showed that in situ ammonia removal may be best able to reduce in-digester ammonia concentrations over a wide range of organic loading rates whereas pre-digestion showed most promise in terms of application due to the flexibility to control each part of the process separately. Further experimental work is required into these scenarios to confirm their viability

Inactivation of Vibrio parahaemolyticus in drinking water

A study was conducted in the Cochin area of India to determine the effect of drinking water on Vibrio parahaemolyticus, a bacterium that contaminates fish harvested from marine and estuarine environments. Times of fresh-water exposure required to inactivate these bacteria are given. Findings indicate that the washing of fish and equipment used to handle the fish in drinking water may decrease in the number of viable Vibrio cells and thus aid in prevention of food poisoning

CO2 lidar system for atmospheric studies

A lidar facility using a TEA CO2 laser source is being developed at the ENEA Laboratories for Atmospheric Studies. The different subsystems and the proposed experimental activities are described

Material growth and characterization for solid state devices

Manganese was used as the dopant for p-type InGaAs layers grown on semi-insulating (Fe-doped) and n-type (Sn-doped) InP substrates. Optical, electrical (Hall) and SIMS measurements were used to characterize the layers. Mn-diffusion into the substrate (during the growth of In GaAs) was observed only when Fe-doped substrates were used. Quaternary layers of two compositions corresponding to wavelengths (energy gaps) of approximated 1.52 micrometers were successfully grown at a constant temperature of 640 C and InP was grown in the temperature range of 640 C to 655 C. A study of the effect of pulses on the growth velocity of InP indicated no significant change as long as the average applied current was kept constant. A system for depositing films of Al2O3 by the pyrolysis of aluminum isopropoxide was designed and built. Deposited layers on Si were characterized with an ellipsometer and exhibited indices of refraction between 1.582 and 1.622 for films on the order of 3000 A thick. Undoped and p-type (Mn-doped) InGaAs epitaxial layers were also grown on Fe-doped InP substrates through windows in sputtered SiO2 (3200 A thick) layers

Probing the non-linear structure of general relativity with black hole binaries

Observations of the inspiral of massive binary black holes (BBH) in the Laser Interferometer Space Antenna (LISA) and stellar mass binary black holes in the European Gravitational-Wave Observatory (EGO) offer an unique opportunity to test the non-linear structure of general relativity. For a binary composed of two non-spinning black holes, the non-linear general relativistic effects depend only on the masses of the constituents. In a recent letter, we explored the possibility of a test to determine all the post-Newtonian coefficients in the gravitational wave-phasing. However, mutual covariances dilute the effectiveness of such a test. In this paper, we propose a more powerful test in which the various post-Newtonian coefficients in the gravitational wave phasing are systematically measured by treating three of them as independent parameters and demanding their mutual consistency. LISA (EGO) will observe BBH inspirals with a signal-to-noise ratio of more than 1000 (100) and thereby test the self-consistency of each of the nine post-Newtonian coefficients that have so-far been computed, by measuring the lower order coefficients to a relative accuracy of $\sim 10^{-5}$ (respectively, $\sim 10^{-4}$) and the higher order coefficients to a relative accuracy in the range $10^{-4}$-0.1 (respectively, $10^{-3}$-1).Comment: 5 pages, 4 figures. Revised version, accepted for publication in Phys. Rev

Tracing very high energy neutrinos from cosmological distances in ice

Astrophysical sources of ultrahigh energy neutrinos yield tau neutrino fluxes due to neutrino oscillations. We study in detail the contribution of tau neutrinos with energies above PeV relative to the contribution of the other flavors. We consider several different initial neutrino fluxes and include tau neutrino regeneration in transit through the Earth and energy loss of charged leptons. We discuss signals of tau neutrinos in detectors such as IceCube, RICE and ANITA.Comment: 27 pages, 19 figure

Magnetic anomalies in Gd6Co1.67Si3 and Tb6Co1.67Si3

The compounds, Gd6Co1.67Si3 and Tb6Co1.67Si3, recently reported to form in a Ce6Ni2Si3-derived hexagonal structure (space group: P6_3 / m) and to order magnetically below 295 and 190 K respectively, have been investigated by detailed magnetization (M) studies in the temperature interval 1.8-330 K as a function of magnetic field (H). The points of emphasis are: We observe multiple steps in the M(H) curve for the Tb compound at 1.8 K while increasing H, but these steps do not appear in the reverse cycle of H. At higher temperatures, such steps are absent. However, this 'staircase' behavior of M(H) is not observed for the Gd compound at any temperature and the isothermal magnetization is not hysteretic unlike in Tb compound. From the M(H) data measured at close intervals of temperature, we have derived isothermal entropy change (Delta S) and it is found that Delta S follows a theoretically predicted H^2/3-dependence