Improvement of biohydrogen production using a reduced pressure fermentation.

This study investigated the effect of reduced pressure on biohydrogen production in an upflow anaerobic sludge blanket (UASB) reactor from whey permeate. The results showed that the reduced pressure fermentation was more effective in enhancing biohydrogen production than dark fermentative hydrogen production at atmospheric pressure. Mesophilic fermentative biohydrogen production was investigated at a constant hydraulic retention time (HRT) of 24 h and increasing organic loading rates (OLRs) of 20, 25, 30, 35 kg COD/m(3) day. The reduced pressure fermentation was successfully operated at all OLRs tested. The maximum proportion of hydrogen in biogas of 47.7 %, volumetric hydrogen production rate (VHPR) of 7.10 L H2/day and hydrogen yield of 4.55 mol H2/kg COD removed occurred at the highest OLR. Increase in OLR affected the hydrogen production in UASB reactor exploited at atmospheric pressure. The reduced pressure process was able to remarkably improve the biohydrogen performance at high OLRs.

Effectiveness of dairy wastewater treatment in a bioreactor based on the integrated technology of activated sludge and hydrophyte system.

The aim of this study was to determine the effectiveness of dairy wastewater treatment in the integrated technology based on the simultaneous use of the activated sludge method (AS) and a hydrophyte system (HS) (AS-HS), in this case, common reed (Phragmites australis) or common cattail (Typha latifolia). Experiments were conducted in an innovative reactor exploited in the fractional-technical scale at the loads of 0.05 mg BOD5/mg.d.m. d (biochemical oxygen demand) and 0.10 mg BOD5/mg.d.m d. The AS--HS enabled improving the removal effectiveness ofbiogenes characterized by concentrations of Ntot., N-NH4 and Ptot. In contrast, the integrated system had no significant reducing effect either on concentrations of organic compounds characterized by BOD5 and chemical oxygen demand parameters or on the structure of AS in the sequencing batch-type reactors.

Respirometric studies on the effectiveness of biogas production from wastewaters originating from dairy, sugar and tanning industry.

The objective of the present study was to determine the effectiveness of biogas production during methane fermentation of wastewaters originating from the dairy, tanning and sugar industries, by means ofrespirometric measurements conducted at a temperature of 35 degrees C. Experiments were carried out with the use of model tanks of volume 0.5 dm3. A high production yield of biogas, with methane content exceeding 60%, was achieved in the case of the anaerobic treatment of wastewaters from the dairy and sugar industries. A significantly lower effect was observed in the case of tanning wastewaters. The effectiveness of the fermentation process decreased with increasing loading of the tanks with a feedstock of organic compounds. By loading a model tank with this feedstock, the effectiveness of treatment ranged from 62.8% to 71.4% residual chemical oxygen demand for dairy wastewaters and from 57.9% to 64.1% for sugar industry wastewaters. The efficiency of organic compound removal from tanning wastewaters was below 50%, regardless of the method applied.

Biodegradability evaluation of dairy effluents originated in selected sections of dairy production.

Main goal of the study was present the results of some respirometric measurements of activated sludge biodegrading the substrate in the wastewater originated in selected sections of the dairy processing line. The following dairy production effluents were analyzed in the research: the pumping station wastewater (combined wastewater from all the sections of the dairy factory), the apparatus room wastewater, the butter section wastewater, the milk reception point wastewater, the cheese section wastewater and the cottage cheese section wastewater. Apart from that, sweet and sour whey, which are secondary products of hard cheese and cottage cheese production, respectively, was the subject of the research. The amount of organic matter being oxidized during a 5-day measurement session was calculated on 1g of the activated sludge biomass. The research was conducted at the temperature of 20 degrees C and 35 degrees C at the applied sludge loading rate of A'=0.2 g BOD g(-1) dry mass d(-1), which ensured complete biodegradation. The results indicated a correlation between a technological process of dairy processing, an ultimate outcome of which was the wastewater analyzed, and dairy wastewater biodegradability. The results confirmed that all dairy processing effluents can be treated together, with the exception of whey, whose complex biodegradation demands may cause too much burden to any wastewater treatment technological system and thus should be managed within a separate installation.

Nitrogen compounds transformation in the biological filter by means of direct energy supply to the biofilm.

The aim of the research was to determine the effect that direct energy supply to the biofilm, which was attached to the packing with its temperature raised, exerts on the course of nitric compounds changes. The experiment was conducted in a laboratory scale. A model reactor which allowed smooth regulations of the packing temperature was used in the experiment. The energy supply was based on the emission of thermal radiation through the reactor's packing to the biofilm. On the basis of the conducted tests it has been found that such a technological solution improves the efficiency of wastewater treatment, nitrification processes in particular. The temperature range between 20 degrees C and 25 degrees C appeared to be optimal for nitrification. At temperatures higher than 25 degrees C anoxic spheres were generated in the deeper layers of the biofilm, which is proved by denitrification.

Linear coordination polymers based on aluminum phosphates: synthesis, crystal structure and morphology.

Several aluminum tris(diorganophosphates) have been synthesized and characterized via elemental analysis, NMR, FT-IR and Raman spectroscopy, as well as powder XRD, and SEM. Single-crystal X-ray diffraction studies revealed that the aluminum tris(diethylphosphate) crystal structure comprises two crystallographically nonequivalent catena-Al[O2P(OEt)2]3 chains propagating along the c-axis. Their parallel orientation favors the formation of closely packed hexagonal domains. PXRD data suggest that other homologues have a similar structure, with the interchain distance closely corresponding to the dimensions of organic ligands. They are also susceptible to a reversible dissociation to ionic species under the effect of primary amines. This feature can be utilized for the synthesis of epoxy nanocomposites.

Compact test apparatus for evaluation of flow erosion of marine coatings.

An apparatus designed and manufactured for evaluation of flow erosion of coatings or layers is presented in this paper. The setup was primarily designed for coatings intended to perform in dynamic marine environments but can be also used for evaluation using fresh water. The concept is based on an in-line flow test cell and modular design allowing good flexibility of varying testing parameters. The flow rate that can be achieved depends on the flow cell geometry and can reach 28 km/h (15 kn) with the presented setup. Temperature may be adjusted between 15 and 35 °C. Particle and metal ion filters are parts of this setup. The dimensions of the apparatus including all components do not exceed 2 m × 2 m × 2 m. The use of the apparatus is illustrated with the results of evaluation of self-polishing anti-fouling coatings and model, silicon wafer grafted layers.

Study of the Molecular Geometry, Electronic Structure, and Thermal Stability of Phosphazene and Heterophosphazene Rings with ab Initio Molecular Orbital Calculations.

Ab initio molecular orbital calculations at the MP2/6-31G level of theory have been used to study the molecular geometry, electronic structure, and the thermal stability of six-membered phosphazene and heterophosphazene rings. The studies included the phosphazene ring [NPCl(2)](3), the carbophosphazene ring [(NCCl)(NPCl(2))(2)], and three thionylphosphazene rings [(NSOX)(NPCl(2))(2)] (X = F, Cl) and [(NSOF)(NPF(2))(2)] and their cations [(NPCl)(NPCl(2))(2)](+), [(NC)(NPCl(2))(2)](+), and [(NSO)(NPY(2))(2)](+) (Y = F, Cl). The ring skeleton of the phosphazene ring, the carbophosphazene ring and of all cation rings adopt a planar conformation; the ring skeletons of the thionylphosphazene rings adopt an envelope conformation. The valence electron charge density of the molecules indicates strong charge separations along their skeleton and is in agreement with Dewar's island delocalization model. The electrostatic potential in the vicinity of the neutral heterophosphazene rings which results from their electronic structure, and the position of the HOMO indicate that a heterolytic cleavage of a ligand and the opening of the ring involving a reaction with a electrophilic cation will most likely occur at the nitrogen atoms close to the heteroatom. The thermal stability of the phosphazene ring with respect to a cleavage of chlorine from phosphorus and the thermal stability of the heterophosphazene rings with respect to the cleavage of the halogen ligand bonded to the heteroatom were studied with several model reactions. Most of the reactions are exothermic. A comparison of isodesmic reactions shows that the thionylphosphazenes molecules are the least thermally stable rings with respect to ionization and that the carbophosphazene molecules are the most thermally stable rings with respect to ionization. The energy gains during the ionization reaction of the rings correlate well with the conformational changes which occur during the reactions.

[Effect of noise, exertion and thermal load on temporary auditory threshold shift (TTS) and on fatigue]. / Wplyw halasu, wysilku fizycznego i obciazenia cieplnego na czasowe podwyzszenie progu sluchu (TTS) i zmeczenie.

Temporary threshold shifts were determined in 14 voluntary subjects who were exposed during one hour to noise levels 70, 85 and 100 dB(A) accompanied by physical exercise (30% VO2max), thermal load (TE = 32.0 +/- 0.8 degrees C), and after combined exposure to these three factors. Before and after each exposure, temporary were measured threshold shifts (TTS2) at frequencies 3, 4 and 6 kHz. The psychophysical fatigue was determined using flicker and blinking tests. The results showed that exposure to noise, noise and thermal load, noise and exercise, and combined noise-exercise -thermal load exposure induced statistically significant increases of TTS values, especially at 85 and 100 dB(A) noise levels. Noise and thermal load, noise and exercise, and the combination of the three did not cause psychophysical fatigue, probably on account of the short duration of exposure. The results of this work show that estimation of exposure to noise, performed by measuring noise levels at workplaces and comparing them with the current standards without considering the effects of exercise and/or thermal load is not sufficient to evaluate occupational exposure and the risk of permanent hearing loss.

In-medium effects on phase space distributions of antikaons measured in proton-nucleus collisions.

Differential production cross sections of K+/- mesons have been measured in p + C and p + Au collisions at 1.6, 2.5, and 3.5 GeV proton beam energy. At beam energies close to the production threshold, the K- multiplicity is strongly enhanced with respect to proton-proton collisions. According to microscopic transport calculations, this enhancement is caused by two effects: the strangeness exchange reaction NY --> K- NN and an attractive in-medium K- N potential at saturation density.

Observation of different azimuthal emission patterns of K+ and of K- mesons in heavy-ion collisions at 1-2 A GeV.

Azimuthal distributions of pi+, K+, and K- mesons have been measured in Au+Au reactions at 1.5A GeV and Ni+Ni reactions at 1.93 A GeV. In semicentral collisions at midrapidity, pi+ and K+ mesons are emitted preferentially perpendicular to the reaction plane in both collision systems. In contrast for K- mesons in Ni+Ni reactions, an in-plane elliptic flow was observed for the first time at these incident energies.

Circadian variations in psychophysiological responses to heat exposure and exercise.

Ten healthy men were tested at 0600, 1200, 1800 and 2400 hours on different days at rest in a laboratory at room temperature followed by 1 h of heat exposure in a climatic chamber at 42 degrees C, 60% rh (50 min rest and 10 min exercise on a cycle ergometer at 50% VO2max). Heart rate, blood pressure, rectal temperature Tre, metabolic rate, number connection test, visual and auditory reaction time, flicker test and catecholamine excretion were measured. Heat exposure and exercise caused lower heart rate acceleration at 2400 hours than at 0600 and 1200 hours, the smallest increase of Tre at 1800 hours, and an increase in metabolic rate greater at 1200 than at 1800 hours. In the afternoon, when, according to the circadian rhythm, the body temperature is highest, the additional heat load produced the smallest physiological effects. Performance efficiency, after heat exposure combined with physical exercise, improved slightly, but diurnal variations did not show significant circadian rhythm.

First evidence for different freeze-out conditions for kaons and antikaons observed in heavy-ion collisions.

Differential production cross sections of K- and K+ mesons have been measured in Ni+Ni and Au+Au collisions at a beam energy of 1.5 A GeV. The K(-)/K(+) ratio is found to be nearly constant as a function of the collision centrality and system size. The spectral slopes and the polar emission pattern differ for K- and K+ mesons. These observations indicate that K+ mesons decouple earlier from the fireball than K- mesons.