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Osmotic dehydration (OD) is one of the commonly used methods for preservation of red beetroot. However, it is a time-consuming process and microbial contamination may occur, resulting in flavor deterioration and market value reduction of products. The present study was aimed to verify whether pulsed pressure osmotic dehydration (PPOD), a newly developed non-thermal food process method can accelerate the impregnation efficiency, improve the quality of final products, and explore the mechanism involved. Results indicated that pulsed pressure of 250 kPa effectively improved the mass transfer of OD process and the following drying process. The Weibull model could describe the drying kinetics very well. The hardness of red beetroot decreased significantly (p < 0.05) during OD process and remained stable after drying process. In addition, the PPOD and constant pressure treatments could preserve the surface color. Preserved beetroots under the pulsed pressure of 250 kPa obtained the highest score on overall acceptability, indicating it was preferred for preserved red beetroot. In conclusion, PPOD was an efficient, economical, and sustainable impregnation method for red beetroot, and these results can serve as a theoretical underpinning for analyzing the involving mechanism and exploring the excellent control parameters of impregnation process in the PPOD food processing. [ABSTRACT FROM AUTHOR]

The anaerobic digestion (AD) of food waste (FW) has been recognised as a low-cost and high-efficiency alternative that mitigates the impacts of the final disposal of FW, while facilitating the production of high value-added by-products, such as biogas and digestate. In this study, the simultaneous incidence of two significant variables in the AD of FW were evaluated: the temperature (20, 35 and 55 °C), which affects the kinetics of the process, and the head space (20, 35 and 50%), which can affect the pH and therefore the biochemical methane potential (BMP). A composite central design was used, and response surface methodology (RSM) and kinetic models (the first-order and Gompertz models) were used to analyse the process. At higher temperatures and smaller head spaces, inhibition phenomena were reduced by the consumption of bicarbonate alkalinity and decreasing the pH, resulting in a higher process performance. The optimal conditions were a temperature of 48.9°C and a head space of 20%. The Gompertz kinetic model fit the process dynamics better and with a lower error than the first-order model. [ABSTRACT FROM AUTHOR]

This study evaluated the kinetics of 2,6-dihydroxybenozic acid and peptone biodegradation at low sludge age by acclimated culture under aerobic conditions. A laboratory-scale sequencing batch reactor was set and fed with peptone mixture. The system was operated at steady-state at a sludge age of 2 days. In order to assess biodegradation kinetics of 2,6-dihydroxybenozic acid and its impact on peptone utilization, a mixture of 2,6-dihydroxybenzoic acid and peptone was fed to mixed culture. After a period of four days, the system became acclimated to simultaneously remove both 2,6-dihydroxybenzoic acid and peptone mixture. A mechanistic model was developed involving model components and kinetic parameters for both substrates. This model was calibrated with related experimental data such as oxygen uptake rate and COD. Biodegradation characteristics and kinetics of peptone and 2,6-dihydroxybenzoic acid was estimated. The evaluation of calibrated model indicated that a group of microorganisms adjusted their enzymatic tools for the utilization of 2,6-dihydroxybenzoic acid resulting in dual microbial community development at low sludge age. [ABSTRACT FROM AUTHOR]

In this paper, the kinetics of Imidacloprid removal from aqueous solution by photo-Fenton processes is presented. Experiments were conducted in batch mode, using a two litre jacketed Pyrex glass reactor, fitted with magnetic stirring, and six 6 W black light fluorescent lamps (λmax 365 nm), arranged in parallel to the reactor axis. The effect of initial Fe(II) concentration (<0.7 mM), incident photon flux (0 to 5·10-6 Einstein s-1), and temperature (288-313K) on the rate of Imidacloprid oxidation is also assessed. When Fe(II) is present as the initial source of iron ions, a first stage of almost instantaneous Imidacloprid removal is observed, followed by a slower process. A simplified kinetic model is described and fitted well experimental data, and could be used for process design, optimization, and control purposes. [ABSTRACT FROM AUTHOR]

The study investigated the effect of biomass concentration on nitrogen removal in a membrane bioreactor by model evaluation of system performance. The steady state operation of a pilot membrane bioreactor fed with domestic sewage at a sludge age of 74 days and an average biomass concentration of 27,000 mg/L was monitored. The results were evaluated by calibration of a suspended growth model designed for this purpose and compared with those of an earlier experiment on the same system operated at a sludge age of 34 days, with a markedly lower biomass concentration. The membrane bioreactor always sustained a dissolved oxygen concentration of around 2 mgO2/L which could be explained by diffusion limitation of dissoved oxygen from the bulk liquid into the floc. Nitrogen removal was controlled and limited by nitrification which occurred only partially throughout the study. The oxidized nitrogen was always fully removed by means of simultaneous nitrification denitrification reducing the level of nitrate to a very low level so that the anoxic tank in front of the membrane bioreactor was totally useless in terms of nitrogen removal. Comparison of the results of the two experimental runs indicated that increasing the biomass concentration drastically changed the system behavior from denitrification limitation to nitrification limitation due to increased constraints on the mass transfer of dissolved oxygen. The selected model could be successfully calibrated for the model parameters by means of substantially higher oxygen half saturation constants for heterotrophs (KOH) and autotrophs (KOA) determined as 2.0 mgO2/L and 2.25 mgO2/L, respectively. [ABSTRACT FROM AUTHOR]

Gamma iron oxide (γ -Fe2O3) powders were prepared by low temperature thermal treatment of the precipitates obtained from a homogeneous solution of iron (III) nitrate and molten stearic acid. The process kinetics and thermal properties of the synthesized product were studied with the aid of differential scanning calorimetric (DSC) technique. Evolution of γ -Fe2O3 particles from the nonaqueous homogeneous solution has been found to follow nucleation and growth type of mechanism. The particle size and their distribution has been estimated from the small angle X-ray scattering (SAXS), X-ray diffraction (XRD), and transmission electron microscopic (TEM) investigations. The results of the investigations show that γ -Fe2O3 nanoparticles exhibit a narrow size distribution with average particle size ranging between 6–8 nm. Presence of superparamagnetic fraction at room temperature is evidenced from the results of Mössbauer spectroscopy. [ABSTRACT FROM AUTHOR]

Ozonation, applied prior to biological processes, has proved to be a very effective chemical treatment step mostly for colour removal when soluble dyes are used in textile finishing operations. Its impact on biological treatability however has not been fully evaluated yet. This study evaluates the effect of ozonation on the quality of wastewater from a textile mill involving bleaching and reactive dyeing of cotton and synthetic knit fabric. The effect of ozonation on COD fractionation and kinetic coefficients defining major biological processes is emphasised. The results indicate that the extent of ozone applied greatly affects the remaining organic carbon composition in the wastewater. The relative magnitude of different COD fractions varies as a function of the ozone dose. Ozonation does not however exert a measurable impact on the rate of major biological processes. [ABSTRACT FROM AUTHOR]