| Popis: |
There are several parameters which affects the efficiency of membrane clarification of fruit juices, such as feed temperature, transmembrane pressure (TMP) and feed velocity. Pomegranate juice undergone the clarification process in a microfiltration unit at different feed canal heights (FCH; 0.4, 1.5 and 2 cm) to evaluate its effect on the permeate flux and fouling mechanism. Changes in permeate flux, main fouling mechanism and occurrence time of each fouling mechanism were evaluated. Results showed that increasing the FCH can increase permeate flux, total and irreversible fouling resistances duo to increase the feed volume on the membrane surface which can increase raw material of clarified juice. Also, cake formation was the dominant fouling mechanism in all membrane units; however, it occurs during the early stages of membrane processing at an FCH of 2 cm in contrast with 0.4 cm in which cake was produced at the steady state. Practical Applications Concentration of nonclarified pomegranate juice caused off flavor because of burn large particles on the walls of the evaporator. Microfiltration can be used to clarify pomegranate juice. To increase the efficiency of the clarification process, the feed canal height (FCH) in the flat sheet module was increased. Results showed that the amount of clarified juice can be increased by increasing the FCH. Also, washing the membrane at high velocity can repair its efficiency after juice treatment; because of the cake formation was the main fouling mechanism. |
