Black hole radiance, short distances, and TeV gravity

Using a derivation of black hole radiance in terms of two-point functions one can provide a quantitative estimate of the contribution of short distances to the spectrum. Thermality is preserved for black holes with $\kappa l_P <<1$. However, deviations from the Planckian spectrum can be found for mini black holes in TeV gravity scenarios, even before reaching the Planck phase.Comment: LaTeX, 4 pages, 1 figure. Misprints correcte

Hybrid electrochemical-granular activated carbon system for the treatment of greywater

Three-dimensional (3D) flow-through electrochemical reactor filled with granular activated carbon (GAC) was employed for the treatment of greywater. Polarization of GAC by the electric field, without the direct contact with the terminal current feeders, resulted in oxidant production and degradation of the adsorbed/electrosorbed contaminants. This in turn enabled electrochemical regeneration of GAC and an improved performance compared to a conventional two-dimensional (2D) electrochemical system. The synergy between electrooxidation and GAC adsorption enhanced the performance of the 3D system by up to 21% and 23% in terms of COD and TOC removal, respectively, compared to the summed up performances of GAC and 2D electrochemical systems operating separately. In long-term operation of the 3D system with a previously saturated GAC, the regeneration efficiency of GAC was increased from 42 to 65% over 31 consecutive runs. Disinfection efficiency was evaluated using Escherichia coli (E. coli), spores of Clostridium perfringens (SCP) and somatic coliphages (SOMCPH) as model organisms for pathogenic bacteria, protozoan surrogate and viruses, respectively. GAC could not remove any of the abovementioned microbial indicators. 2D and 3D electrochemical systems achieved similar log removals of E. coli (4.6–5.1 log), SCP (0.1–0.6 log) and SOMCPH (3.2–3.3 log). However, the proportions of viable cells from the total cells adsorbed onto the GAC was reduced from 72% to 22% when an electric field was applied, further confirming that electrochemical polarization of GAC caused the killing of the adsorbed microorganisms. Simultaneous adsorption/electrosorption and electrocatalysis in the GAC packed bed lowered the energy consumption from 46 kWh kg COD removed in conventional 2D system, to 30 kWh kg COD removed in the 3D electrochemical system, thus enabling significant savings in the operational costs

Disinfection by Chemical Oxidation Methods

Poor quality in drinking water is primary cause of pathogen transmission and responsible of varied infectious diseases. Methods of water treatment for human consumption must pay special attention on microbiological safe disinfection. Indeed, from the past few years laws all around the world have included new, more stringent water quality parameters. Chlorination and other mainly used conventional disinfection processes usually do not achieve full inactivation of all microorganisms present in real water supplies, whereas the presence of even low concentrations of organic matter can lead to form harmful disinfection by-products. Protozoan parasites Giardia sp. and Cryptosporidium sp. are some of the microorganisms that cannot be completely inactivated via chlorination under the same contact times typical of bacteria or virus elimination. It has increased toxicological and microbiological risks as well as operational costs. Disinfection by the advanced oxidation process more intensively studied in the past few years has been reviewed including Fenton and photo-Fenton processes and photocatalytic and electro-catalytic variants; this vibrant topic still remains partially uncovered in the available scientific background, which has motivated many recent researches and publications. This chapter is then devoted to briefly review the most recent reports studying the disinfecting potential displayed by mentioned AOPs with respect to widely and currently used conventional techniques. Revision of the inactivation of water-borne pathogens including E. coli, total coliforms, parasites as Giardia and Cryptosporidium, and virus such as coliphages has focused on advantages and disadvantages in application of every particular AOP, their disinfecting mechanisms, and the main parameters affecting the disinfection response