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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

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2005

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Vol. 31, nr 3-4

109-118

EN

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.

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Ultrafiltration of oil-in-water emulsion: flux enhancement with static mixer

Koris A., Kristic D., Hu X., Vatai G.

Environment Protection Engineering

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2005

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Vol. 31, nr 3-4

163-176

EN

Conventional methods of oily emulsion separation are not effective in removing small oil droplets and emulsions, especially if the emulsion is stable and the oil concentration is low. This paper deals with the oil removal from oil-in-water emulsion by an ultrafiltration membrane under different operating condi-tions of a novel flux enhancement method. Separation of oily water and wastewater by membrane filtra-tion is a well-known process. Generally, because of heavy concentration polarization and membrane fouling, a single-stage membrane process is not economical and usually does not provide satisfying results in retention. In our experiments, 20 nm pore size ceramic tubular membranes were used. In order to reduce concentration polarization and membrane fouling, the use of static turbulence promoters, such as rods, differently shaped inserts and static mixers, has been considered during cross-flow ultrafiltration and microfiltration with different fluids. Helix-like plastic static turbulence promoter was installed in the experimental apparatus

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Mass-transfer model for humic acid removal by ultrafiltration

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

Environment Protection Engineering

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2005

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Vol. 31, nr 3-4

145-152

EN

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.