基于正渗透膜技术的全脂牛乳浓缩

Concentration of Milk by Forward Osmosis Membrane

利用正渗透膜技术浓缩全脂生牛乳以制备总固形物浓度高于40%的浓缩乳。探究汲取液种类、汲取液浓度、试验温度、时间、跨膜压力等因素对于试验的影响。选择CaCl_(2)作为试验的汲取液,在控制跨膜压力相同的条件下,配制使用12%,14%等不同浓度汲取液,在15,20及30℃三个不同温度条件下进行浓缩试验。试验表明,膜通量随汲取液浓度增加而增加,过高的汲取液浓度可能导致钙离子进入浓缩乳中。膜通量随试验温度增加而增加,温度增加将导致系统内微生物生长,30℃试验温度制备的浓缩乳菌落总数是相同条件下15℃制备的浓缩乳的近10倍。膜通量随试验时间增加而降低,受到膜表面附着污垢逐渐增多和浓差极化现象的影响,膜通量最后可能趋近于零。跨膜压力增大时膜通量同样增大。

The purpose of the experiment is to use forward osmosis membrane technology to concentrate whole-fat raw milk to prepare concentrated milk with a total solids concentration higher than 40%.Explore the influence of factors such as the type of draw solution,concentration of draw solution,experimental temperature,time,and transmembrane pressure on the experiment.Choose CaCl_(2)as the draw solution of the experiment,under the same conditions of controlling the transmembrane pressure,prepare and use 12%,14%and other different concentrations of the draw solution,and conduct the concentration experiment under three different temperature conditions of 15,20 and 30℃.The conclusion is that the membrane flux will increase with the increase of the concentration of the draw solution,but higher concentration of the draw solution may cause calcium ions to enter the concentrated milk.When the flux increases with the increase of the temperature,the increase of temperature will lead to the growth of microorganisms in the system.The total number of colonies in concentrated milk prepared at an experimental temperature of 30°C are nearly 10 times that of concentrated milk prepared at 15°C under the same conditions.The flux decreases with the increase of the running time.Affected by the gradual increase of fouling on the membrane surface and the phenomenon of concentration polarization,the membrane flux may eventually approach zero.When the transmembrane pressure increases,the membrane flux also increases.