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Nowadays, the membrane filtration technique is a commonly used method for the separation of whey. The most significant limitation of membrane applications is fouling, which causes flux decline. During this work, regenerated cellulose membranes covered by TiO2-nanoparticles were investigated and applied to the separation of whey solution. Experiments were carried out in a dead-end ultrafiltration cell, and the changes in filtration parameters and the photocatalytic effects of the UV irradiated TiO2 modified membrane surface on the membrane fouling were examined. Our results showed that the water flux decreased with increasing TiO2 layer thickness, but the retention of turbidity and of COD increased. After separation, the membrane surface was cleaned by UV irradiation by means of photocatalytic oxidation. It was found that the original flux was recoverable, while the retention of the membrane decreased after cleaning.
The importance of the treatment of water and wastewater has been steadily increasing because of the ever greater demands to eliminate environmental pollution. Pressure-driven membrane separation processes, including ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), have been widely used in water and wastewater treatment and are applied on an industrial scale worldwide. The aim of our paper is to introduce the results of our research team on this field. The main research area within the membrane separation was the reduction of resistances. The effect of ozonation, vibration and application of dolly particles were examined in our scientific works.
Abstract
In recent years response surface analysis has been increasingly used to optimise membrane separation. It has many advantages, such as reducing the number of experiments to be performed, which requires lower energy consumption and significantly less laboratory work. For more accurate data analysis and forecasting, mathematical models are used that analyse the relevance of the factors examined and the interaction effects between the factors. In this research, two experimental designs that use response surface methodology are presented, namely, the central composite design and the Box–Behnken design. After the general characterisation of the experimental designs, their application in membrane technology is presented.
Honey is produced by honeybees from nectar, sap of plant parts, or the juicy material secreted by sucking insects living on trees. It is rich in nutritionally useful components, the occurrence of which highly depends on the botanical and geographical origin of honey. Our goal is to develop a new, rapid, and accurate combination of analytical methods for identification of botanical and geographical origin.
Physicochemical parameters (pH, electrical conductivity, moisture, and ash content), colour (L*a*b*), and antioxidant properties were determined in addition to correlative techniques, such as electronic tongue and near infrared spectroscopy. For the statistical evaluation ANOVA, principal component analysis, and linear discriminant analysis were applied.
Results showed significant differences (P<0.05) in physicochemical properties, colour, and antioxidant capacity according to the botanical origin of honeys. Electronic tongue (ET) and near infrared spectroscopy (NIR) techniques were useful in the identification of the botanical and geographical origin, showing generally good accuracy.
The physicochemical parameters are important and can serve as reference methods, completing NIR and ET as target techniques, which are promising, but need further improvement for the determination of honey origin.
Abstract
In this study, statistical analysis was performed to investigate the influence of operational parameters based on experimental results. The research aimed to know whether a long-term discontinuous module vibration operation is possible without adversely affecting filtration efficiency. Polymer membranes were compared by surface characteristics with contact angle measurements and selected for further membrane filtration experiments for dairy wastewater treatment. The effect of the main operational parameters, membrane module vibration amplitude (A vibr.) and transmembrane pressure (TMP), was investigated using a vibratory shear enhanced processing (VSEP) module with ultrafiltration (UF) and nanofiltration (NF) membranes. Components of the permeates, including chemical oxygen demand (COD), were measured, and membrane rejections were calculated to compare with threshold limit values. The results suggest that proper combination of A vibr. and TMP could mitigate membrane fouling. However, discontinuous module vibration resulted in more clogged membrane with lower fluxes, but slightly higher rejections. We conclude that investigating the significance of operational parameters is necessary for a wider, more energy and environment-friendly application in wastewater treatment.
