2004 年 29 巻 1 号 p. 58-65
In the ultrafiltration of honey, filtration efficiency can not be expressed by permeate flux because it is necessary to dilute raw honey with water. Instead, rate of recovered sugar (RRS) which considers permeate flux and sugar content, was employed as an indicator of the filtration efficiency in this study.
The effect of dilution on filtration efficiency was that RRS increased with a decrease in sugar content at initial stage of filtration. However, at concentration factor (CF) above 1.5, RRS at sugar content of 40% was higher than that at sugar content of 30%. This result was probably caused by changes in characteristics of suspended solids in raw honey due to dilution. In this case, the changes were small when the sugar content was 50%.
The effect of operation temperature on filtration efficiency was shown that high RRS was observed at 50°C rather than 20°C and 30°C, however, temperature influenced cake resistance less than sugar content during filtration.
The effects of operation pressure and cross-flow velocity on filtration efficiency were that when cross-flow velocity was 1.07-1.6 m/s, RRS increased as pressure increased. Whereas influence of cross-flow velocity on RRS decreased as pressure became decreased.
Furthermore, total operation energy was easily calculated using inlet pressure under several filtration conditions to obtain a constant volume of permeate.
At constant pressure, the cross-flow velocity was proportional to the energy. At constant cross-flow velocity, there were optimum pressures at each cross-flow velocity for useful filtration.