Cecilia Hodúr

Comparison of the effects of microwave irradiation with different intensities on the biodegradability of sludge from the dairy- and meat-industry

Microwave (MW) irradiation is a relatively new possibility of conditioning and pretreating for wastewater sludge. Following its application in the telecommunications and food-industries, the environmental use of this technique has come into the limelight in recent years, and has become increasingly popular. Various publications have dealt with the examination of the effects of MW irradiation in municipal sludge-handling processes. We focused on the effects of MW irradiation at different power levels on solubilization (sCOD/tCOD), biodegradation and anaerobic digestion of sludge from the food-industry. For evaluating the efficiency of MW pre-treatment, the changes in the soluble fraction of the organic matter, the VS/TS ratio, the biogas yield, the methane content in the biogas, and the rate of batch mesophilic digestion were used as control parameters. Additionally, the energetic efficiency of MW pre-treatment was also examined. The results were compared with those of conventional heat (CH) treatments of the same sludge. The MW treatment proved to increase both the sCOD/tCOD and the VS/TS ratio. Furthermore, the biogas and methane yields increased during the digestion of the MW-pretreated food-industry sludge. A higher MW power level generally enhanced the biogas and methane production. Energetically, the most economic pre-treatment of sludge from dairy and meat processing was at a power level of 1.5 Wg(-1) and 2.5 Wg(-1) MW respectively; the surplus energy content of the enhanced biogas product could not compensate the extra energy demand of the stronger MW pre-treatments.

Microwave-Assisted Extraction of Anthocyanins from Black Currant Marc

This paper reports on the process optimization study of anthocyanin extraction from black currant marc by microwave-assisted extraction (MAE) using acidic solvents. Maximum yields of anthocyanins were achieved at pHu20092 with an extraction time of 10xa0min with a microwave power of 700xa0W. The anthocyanin yields in MAE were compared with those obtained by conventional solvent extraction (CE) using citric or hydrochloric acids, and citric acid and water with a sulfur concentration of 50xa0ppm. A significant reduction of extraction time was achieved using MAE; maximum anthocyanin yield was obtained after 10xa0min using MAE, while using CE only after 300xa0min. Furthermore, the amount of solvent used halved; the mass ratio of marc to solvent was 1:40 in CE and 1:20 in MAE. Additionally, the final anthocyanin concentration in the solvent phase of MAE increased by 20xa0% compared to the conventional extraction with hydrochloric acid at pHu20092 and temperature of 80xa0°C. The results suggest that microwave-assisted extraction is a more efficient technique for the extraction of valuable compounds from black currant residue.

Berry Pectins: Microwave-Assisted Extraction and Rheological Properties

Press residues formed during processing of berry fruits are regarded as valuable pectin sources. In this work, pectins were extracted from press residues obtained by processing of various fresh berry fruits: red and black currant, raspberry and elderberry. The extraction was carried out by conventional and microwave-assisted methods. Comparing the two methods, the microwave-assisted process gave significantly better results. The rheological behaviour of the pectins extracted was studied, and we found that the gels of pectins from berry press residues are somewhat weaker than gel of commercial citrus pectin, but stronger than that of commercially available apple pectin. Red currant pectin was found to possess outstanding values regarding gel-forming capacity and thickening effect.

Treatment of oily wastewater by combining ozonation and microfiltration

AbstractIn process industries, a large amount of wastewater is generated in the form of oil-in-water emulsions, which cannot be treated effectively using traditional physical methods. The aim of our investigation was to examine the applicability of the membrane technique and the effect of pre-ozonation in oily wastewater treatment. Pre-ozonation followed by microfiltration (MF) was investigated to determine the main effects of ozonation on the oily water and the filtration parameters such as permeate flux, organic content retention and membrane fouling. Experiments were carried out with a laboratory-scale batch-stirred filtration device, using polyethersulphone MF membranes with a pore size 0.2u2009μm. The model oily wastewater that was used in these experiments contained petroleum. The results demonstrated that the chemical oxygen demand could be eliminated more effectively through the combination of ozone pre-treatment and membrane filtration, compared to membrane filtration alone.

Investigation of module vibration in ultrafiltration

AbstractMembrane fouling is still a critical issue which limits the application of industrial membrane utilizations. Membrane processes operating at a high shear rate are frequently used to control flux decline by reducing the deposition of particles on the membrane surface. In this work, ultrafiltration (UF) of a dairy model and industrial wastewaters was investigated. Membrane module vibration and no-vibration mode were compared by a laboratory mode vibratory shear enhanced processing device during membrane filtration with the same operational parameters. Membrane fluxes, rejections, and energy consumption were measured and calculated for comparison of the vibration effectiveness. Turbidity, chemical oxygen demand, and total organic carbon were measured. The UF experiments were carried out with constant parameters at a temperature of 50°C and recirculation flow rate of 910u2009Lu2009h−1 at 0.8u2009MPa. Furthermore, to understand the fouling mechanisms in depth, contact angles of the clean, prewetted, and fouled mem...

Treatment of waste thermal waters by ozonation and nanofiltraton

After their use for heating, e.g. in greenhouses, waste thermal waters may cause environmental problems due to their high contents of ions, and in some cases organic matter (associated with an oxygen demand) or toxic compounds. The aims of this work were to decrease the high organic content of waste thermal water by a combination of ozone treatment and membrane separation, and to investigate the accompanying membrane fouling. The results demonstrated that the chemical oxygen demand and the total organic content can be effectively decreased by a combination of ozone pretreatment and membrane filtration. Ozone treatment is more effective for phenol elimination than nanofiltration alone: with a combination of the two processes, 100% elimination efficiency can be achieved. The fouling index b proved to correlate well with the fouling and polarization layer resistances.