Performance analysis of a denitrifying wastewater treatment plant

The cleaning performance of an activated sludge wastewater treatment plant for biological nitrogen removal was evaluated based on the Activated Sludge Models No. 1 (ASM1) and No. 3 (ASM3). The COST predenitrification benchmark plant was considered as a case study. Several treatment plant performance indexes were defined based on performance indicators and operating cost factors. Plant operation was evaluated for three dynamic disturbance scenarios corresponding to dry, rain, and storm weather conditions. The aeration rate was seen to be the most sensitive process parameter for this case study, and the nitrate recycle flow rate ratio was the least sensitive of all parameters analyzed. Different qualitative predictions were obtained from the two models, as a result of different model structures. For all three weather scenarios, the sludge production predicted by the ASM1 model increases slightly as the oxygen transfer rate increases; in contrast, the sludge production decreases for the ASM3 model. However, the resulting difference in the sludge treatment cost does not qualitatively modify the cost performance index profile. For all control handles considered the rain weather scenario showed the highest cost performance index and the lowest global cleaning efficiency. Electronic Publication     

Modification of kaolinite surfaces through mechanochemical activation with quartz: A diffuse reflectance infrared fourier transform and chemometrics study

Studies of kaolinite surfaces are of industrial importance. One useful method for studying the changes in kaolinite surface properties is to apply chemometric analyses to the kaolinite surface infrared spectra. A comparison is made between the mechanochemical activation of Kiralyhegy kaolinites with significant amounts of natural quartz and the mechanochemical activation of Zettlitz kaolinite with added quartz. Diffuse reflectance infrared Fourier transform (DRIFT) spectra were analyzed using principal component analysis (PCA) and multi-criteria decision making (MCDM) methods, the preference ranking organization method for enrichment evaluations (PROMETHEE) and geometrical analysis for interactive assistance (GAIA). The clear discrimination of the Kiralyhegy spectral objects on the two PC scores plots (400-800 and 800-2030 cm(-1)) indicated the dominance of quartz. Importantly, no ordering of any spectral objects appeared to be related to grinding time in the PC plots of these spectral regions. Thus, neither the kaolinite nor the quartz are systematically responsive to grinding time according to the spectral criteria investigated. The third spectral region (2600-3800 cm(-1), OH vibrations), showed apparent systematic ordering of the Kiralyhegy and, to a lesser extent, Zettlitz spectral objects with grinding time. This was attributed to the effect of the natural quartz on the delamination of kaolinite and the accompanying phenomena (i.e., formation of kaolinite spheres and water). The mechanochemical activation of kaolinite and quartz, through dry grinding, results in changes to the surface structure. Different grinding times were adopted to study the rate of destruction of the kaolinite and quartz structures. This relationship (i.e., grinding time) was classified using PROMETHEE and GAIA methodology.     

The effect of context-related moderators on the internationalization-performance relationship: Evidence from meta-analysis

Abstract and Key Results

Towards Understanding Excited-State Properties of Organic Molecules Using Time-Resolved Soft X-ray Absorption Spectroscopy

The extension of the pump-probe approach known from UV/VIS spectroscopy to very short wavelengths together with advanced simulation techniques allows a detailed analysis of excited-state dynamics in organic molecules or biomolecular structures on a nanosecond to femtosecond time level. Optical pump soft X-ray probe spectroscopy is a relatively new approach to detect and characterize optically dark states in organic molecules, exciton dynamics or transient ligand-to-metal charge transfer states. In this paper, we describe two experimental setups for transient soft X-ray absorption spectroscopy based on an LPP emitting picosecond and sub-nanosecond soft X-ray pulses in the photon energy range between 50 and 1500 eV. We apply these setups for near-edge X-ray absorption fine structure (NEXAFS) investigations of thin films of a metal-free porphyrin, an aggregate forming carbocyanine and a nickel oxide molecule. NEXAFS investigations have been carried out at the carbon, nitrogen and oxygen K-edge as well as on the Ni L-edge. From time-resolved NEXAFS carbon, K-edge measurements of the metal-free porphyrin first insights into a long-lived trap state are gained. Our findings are discussed and compared with density functional theory calculations.     

Catalytic co-pyrolysis of packaging plastic and wood waste to achieve H2 rich syngas

In this work, the co-pyrolysis of pine sawdust and low-density polyethylene (LDPE) was performed in a two-stage fixed-bed reactor to achieve hydrogen-rich syngas and to investigate the effect of the parameters on gas yield and composition. Gas chromatography was used to confirm the content of the gas products. The pyrolysis was supported with Ni (in 5-25 wt%) loaded on activated carbon (AC). The maximum hydrogen concentration was 392.8 mmol g⁻¹ sample, which was achieved by the use of the 10% Ni-AC catalyst. The influence of Ni loading on supporter was investigated by scanning electron microscope and transmission electron microscope techniques besides the thermogravity analysis. The increasing size of the Ni particles can be observed as a function of the Ni concentration on the catalyst. Carbon deposition was detected and the amorphous carbon seems more dominant than filamentous form. In addition, the effect of fluid residence time (water inlet and purge gas) on syngas yield was studied. Three different fluid residence times were investigated, and among them, the highest hydrogen yield was 392.8 mmol g⁻¹sample at 1.57 minutes residence time. Furthermore, the catalyst lifetime was studied using 10 wt% of Ni containing AC, and the average hydrogen concentration was 196.0 mmol g⁻¹ sample over 15 cycles.     

Replacement of traditional emulsifying salts by selected hydrocolloids in processed cheese production

Different hydrocolloids were examined as possible replacements for traditional phosphate- and citrate-based emulsifying salts in processed cheese production. The following hydrocolloids (at concentrations in the final product of ≤1.0%, w/w) were chosen: modified starch (with bound sodium octenyl succinate), low methoxyl pectin (alone or combined with lecithin), locust bean gum, κ-carrageenan and ι-carrageenan. The products were assessed by sensory analysis, microscopic image analysis and dynamic oscillatory rheometry. Modified starch, locust bean gum and low methoxyl pectin could not be recommended as replacements for traditional emulsifying salts. Model processed cheeses without traditional emulsifying salts of 40% (w/w) dry matter and 55% (w/w) fat-in-dry matter containing 1.0% (w/w) κ-carrageenan or ι-carrageenan were found to be homogeneous, however the products were hard with fracturable texture.     

3D modelling of coupled mass and heat transfer of a convection-oven roasting process

A 3D mathematical model of coupled heat and mass transfer describing oven roasting of meat has been developed from first principles. The proposed mechanism for the mass transfer of water is modified and based on a critical literature review of the effect of heat on meat. The model equations are based on a conservation of mass and energy, coupled through Darcy's equations of porous media — the water flow is mainly pressure-driven. The developed model together with theoretical and experimental assessments were used to explain the heat and water transport and the effect of the change in microstructure (permeability, water binding capacity and elastic modulus) that occur during the meat roasting process. The developed coupled partial differential equations were solved by using COMSOL Multiphysics®3.5 and state variables are predicted as functions of both position and time. The proposed mechanism was partially validated by experiments in a convection oven where temperatures were measured online.