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2 Environment Protection Engineering

2 2005

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Ultrafiltration of oily emulsion for metal cutting fluid: role of feed temperature

Hu X., Bekassy-Molinar E., Vatai G., Koris A.

Environment Protection Engineering

2005

Vol. 31, nr 3-4

109-118

The oil-in-water emulsions as industrial wastewaters are produced in a large amount in the metal working, food producing and other industrial branches. Separation of oil from water, both being the phases of emulsion, is economically realizable by membrane techniques. There are so many membrane operation factors which influence the permeate flux, such as transmembrane pressure, feed concentration, feed temperature, design of flow route and so on, besides membrane material compositions. This article describes the results of water removal from oil-in-water emulsion by different ultrafiltration membranes at variable temperatures. The experimental results show that the effect of feed temperature on the permeate flux depends on the variations of membrane property (including membrane material and MWCO), concentration of feed emulsion and transmembrane pressure. Based on the relationship between the gel resistance and the feed temperature it was found that the gel resistance decreased with temperature. The concentration polarization of PES (polyether-sulfone) membrane is higher than that of PVDF (polyvinylidene fluoride) membrane. At higher emulsion concentration the concentration polarization becomes very serious. In our experimental conditions, the enhancement effect of the temperature on the permeate flux at higher emulsion concentration is better than that of lower emulsion concentration. Some models of the effects of feed temperature on permeate flux variation were presented and analyzed based on the experimental data. In addition, the COD values and oil concentrations in the permeate were analyzed at different temperatures.

Mass-transfer model for humic acid removal by ultrafiltration

Galambos I., Csiszar E., Bekassy-Molinar E., Vatai G.

Environment Protection Engineering

2005

Vol. 31, nr 3-4

145-152

Humic acid (HA) molecules present in the soil dissolve in the water and can be found also in the well water. They have different size, molecular weight and structure. It is important to remove these molecules because they build carcinogenic by-products when they react with disinfectants. Membrane filtration can be an effective method of removing humic acid from water. Earlier experiments have proved that ultrafiltration membranes are proper for this task. The aim of this study was to find a new formula which helps to design a well-water filtration. We needed to model the mass transfer during the membrane filtration and to calculate the mass-transfer coefficient. The calculations were carried out in two ways: by using the results of laboratory measurements and criterial equations and by using heat-transfer analogy. The results reveal that the values measured and calculated are in agreement, the heat-transfer analogy can be applied and the equations are useful for designing the membrane for drinking water treatment.