چكيده به لاتين
Proteins have important applications in industry, medicine and food industries. Considering the high value of the materials existing in the whey such as proteins, the separation of these materials is of great importance. Less energy consumption, more efficiency and easier application of membrane technology in comparison to the other similar processes are some of the reasons why it is a popular process for industries owners. The main problem of membrane processes is membrane fouling which strongly affects the membrane performance and significantly decreases the separation efficiency within a short time. Many methods have been introduced to prevent membrane fouling and to reduce its negative effects on membrane separation. In the present study the effect of electric field on membrane fouling with whey protein has been studied. This research is done in two individual parts: Experimental study and simulation. In the experimental part two types of tests are performed. First type is performed in order to fix membrane fouling. In these tests, after fouling of membrane, the pressure is reduced to 0.24 bar in 5 minutes and the electric field is applied and then the pressure is returned to the initial value and the flux increment is calculated. The second type test is done in order to prevent membrane fouling under the effect of electric field and the flux passing through the membrane is compared in the presence and absence of the electric field. This tests are performed in three voltages of 20, 23 and 26 volts, three concentration of 0.01, 0.1 and 1 %wt and pH of 7, 8 and 9 and the obtained results are compared in the form of increment percentage of the flux passing through the membrane under the effect of applied electric field. The results indicated that in both test types, increasing the protein concentration to more than nearly 0.01 %wt decreases the effect of the electric field. In the first type of the tests, fouling decreases until the voltage of nearly 23 volts and after that increasing voltage doesn’t have a significant effect on reducing the membrane fouling. In type two test, the higher voltage is, the greater the impact of electric field on fouling reduction will be. The results also indicates that in both types of tests, increasing pH increases effect of the electric field. In the computational part of the research, the effect of electric field on the membrane fouling is simulated relying on the capabilities of computational fluid dynamics (CFD) method using COMSOL software. This model has been validated using the data obtained from experimental part and has been investigated based on experiment design in different operating conditions. Finally the performance of electric field in reducing membrane fouling with whey protein was proved in both simulation and experimental parts.
Keywords: Whey protein, Membrane fouling, Electric Field, Experiment design, Computational fluid dynamics
