Effects of filter additives on cake filtration performance
Effects of various additives, such as diatomaceous earth, inorganic adsorbent, and polymeric flocculant, on cake filtration performance were evaluated. By performing the standard vacuum filtration experiments under a constant pressure condition, we quantified their ability to reduce cake compressibility and to remove fine particulate matters. From the flux decline curves obtained, we used modified Ruth equation to determine the cake compressibility index. The filtrate clarity was quantified by measuring its turbidity spectrophotometrically. Diatomaceous earth filter aid was very effective in reducing the compressibility thereby improving filtrate flux. Calcium phosphate adsorbent was more effective in clarity improvement than in flux enhancement, whereas an anionic flocculant was effective in both aspects. When these additives were used together, the expected additive, synergic effect was not realized. However, about 3.5 times higher initial flux and 6-fold improved clarity were obtained as compared to the control experiment. Experimentally obtained flux decline curves were perfectly fitted into one of the Hermia’s blocking filtration law equations. Also, it was experimentally observed that the compressibility reduction improved filtrate clarity in a linear fashion. This type of approach is useful to quantitatively determine each additive’s characteristics and thus to maximize the performance of cake filtration operations.
Key wordsCake Filtration Filter Additives Cake Compressibility Filtration Flux
Unable to display preview. Download preview PDF.
- Green, S. and Wase, D. A. J., “Practical and Theoretical Aspects of Inorganic Adsorbents Technology in Downstream Processing-A Review”,Process Biochemistry, December, 200 (1986).Google Scholar
- Hermia, J., “Constant Pressure Blocking Filtration Laws-Application to Power-Law Non-Newtonian Fluids”,Trans IChemE,60, 183 (1982).Google Scholar
- Kim, S. J., Lee, E. K. and Nam, C. H., “Reaction Characteristics and Kinetic Analysis of Enzymatic Hydrolysis of Corn Gluten Meal Using Alkaline Protease”,Korean J. Biotech. Bioeng.,10(5), 540 (1995).Google Scholar
- McCabe, W. L. and Smith, J. C., “Unit Operations of Chemical Engineering”, 2nd ed., McGraw-Hill, New York, 892 (1967).Google Scholar
- Perry, R. H. and Chilton, C. H., “Chemical Engineers’ Handbook”, 5th ed., McGraw-Hill Co., New York, 19 (1973).Google Scholar