Elimination of micropollutants in activated sludge reactors with a special focus on the effect of biomass concentration

This study aimed to investigate the effects of sludge retention time (SRT), hydraulic retention time (HRT), and biomass concentration (CTSS) in activated sludge systems on removal of various micropollutants (MPs), covering a wide spectrum of biodegradability. The influence of biomass concentration on the classical pseudo-first-order rate constant was verified. Results showed that the removal rate constants were affected by both the HRT and SRT. The enhancement of the SRT increased the removal of all the MPs except for two macrolide antibiotics. Application of a higher HRT also improved MP removal, as was expected from the measured removal rate constants. More interesting, our results indicated that, logically, the increase of biomass concentration (expressed as total suspended solids CTSS) from 3 to 5 gTSS L−1 significantly enhanced the removal rate of the highly and moderately degradable compounds. Conversely, a further increase to 8 gTSS L−1 produced only an unexpected moderate effect, showing that the rate was not proportional to biomass concentration, contrary to what is generally postulated. Therefore, the use of classical kinetic models is questionable, since they do not cover the entire range of boundary conditions in activated sludge systems. This work opens new research paths and suggests potential improvements to processe

Control of Spatial Organization of Gold Nanoparticles Using Cylindrical Nanopores of Block Copolymers Films

Abstract In this paper, a sequential process of elaboration of hybrid nanostructured composite films has been proposed. The combination of phase separation in poly(styrene-block-4vinylpyridine) (PS-P4VP) block copolymer leading to the formation of nanopores, and gold nanocolloids synthesis confined in the nanoholes has allowed the facile fabrication of hexagonally arranged gold nanoparticles (NPs) onto silicon wafer. In particular, the nucleation and growth of gold nanoparticles took place within the nanopores, where they are confined in both size and shape the formed Au NPs. The resulting hybrid nanoscomposite has been characterized by Atomic Force Microscopy (AFM) and X-Ray Spectroscopy (XPS). This facile and simple process represents an opened pathway to several technologically important materials fabrication such as hierarchical and ordered crystal architectures. Indeed, the approach based on solvent phase, which is particularly attractive due to its low energy requirement, and the safety and environmentally gentle processing conditions

HIV infection and HERV expression: a review

The human genome contains multiple copies of retrovirus genomes known as endogenous retroviruses (ERVs) that have entered the germ-line at some point in evolution. Several of these proviruses have retained (partial) coding capacity, so that a number of viral proteins or even virus particles are expressed under various conditions. Human ERVs (HERVs) belong to the beta-, gamma-, or spuma- retrovirus groups. Endogenous delta- and lenti- viruses are notably absent in humans, although endogenous lentivirus genomes have been found in lower primates. Exogenous retroviruses that currently form a health threat to humans intriguingly belong to those absent groups. The best studied of the two infectious human retroviruses is the lentivirus human immunodeficiency virus (HIV) which has an overwhelming influence on its host by infecting cells of the immune system. One HIV-induced change is the induction of HERV transcription, often leading to induced HERV protein expression. This review will discuss the potential HIV-HERV interactions

Effect of treatment with soda and dimethoxydimethylsilane on water absorption and thermal stability of olive pomace flour and date stone

In this article it was investigated the effect of chemical modification of the surface of olive pomace fiber and local date stones on their physical and thermal properties. The use of soda treatment, the dimethoxydimethylsilane, and alkaline pretreatment followed by treatment with dimethoxydimethylsilane fibers leads to an improvement of the thermal stability of the fibers and a reduced absorption of water, which allows us to recommend the use of its flour as fillers or reinforcements in the development of Wood Plastic Composite

Physicochemical characterization of some solid materials by inverse gas chromatography

New equations and models on two-dimensional state of solid surfaces were previously elaborated in many other studies. Results obtained were used in this paper to determine and quantify physicochemical properties of some solid surfaces, and especially, to study the acid-base superficial characteristics of solid substrates like oxides, carbon fibers, textiles, etc. The technique used was the inverse gas chromatography (CGI) at infinite dilution. The acid-base constants were calculated for many solid surfaces: MgO, ZnO, textile materials and carbon fibers

TiO2-Supported Pd as an Efficient and Stable Catalyst for the Mild Hydrotreatment of Tar-Type Compounds

The mild hydrotreatment of a model mixture of tar-type compounds (i.e., naphthalene, 1-methylnaphthalene, acenaphthylene, and phenanthrene) to produce partially hydrogenated products in the range of C9–C15 was studied over Pd supported on TiO(2) possessing different crystalline phases. Pd-based catalysts were prepared and characterized by ICP analysis, XRD, N(2) adsorption isotherms, HR-TEM, and NH(3)-TPD, among others. The hydrotreatment activity and selectivity towards the desired hydrogenated products (i.e., tetralin and others) increased with both the acidity and surface area of the catalyst, along with the presence of small and well distributed Pd nanoparticles. For the selected 1.3 wt% Pd/TiO(2) nano catalyst, the operational conditions for maximizing tar conversion were found to be 275 °C, 30 bar of H(2), and 0.2 g of catalyst for 7 h. The catalyst revealed remarkable hydrotreatment activity and stability after several reuses with practically no changes in TiO(2) structure, quite low carbon deposition, and any Pd leaching detected, thus maintaining both a small Pd particle size and adequate distribution, even after regeneration of the catalyst. Additionally, the Pd/TiO(2) nano catalyst was demonstrated to be more active than other commonly used metal/alumina and more selective than metal/USY zeolites in the mild hydrotreatment of tar-type compounds, thus providing an efficient catalytic route for obtaining partially hydrogenated C9–C15 hydrocarbons useful as jet-fuel components or additives (improvers), as well as chemicals and solvents for industrial applications

Hybrid catalysis by coupling enzymatic catalysis with heterogeneous catalysis in cellulose conversion into chemicals

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