SPECIFIC CAKE RESISTANCE - MYTH OR REALITY

The specific cake resistance is considered to be the key factor in the characterization of sludge dewaterability. The use of this parameter without knowing how it is derived and the conditions under which it ca n be used has been creating a great deal of confusion in the literatur e. Moreover, the lack of a universally agreed test method to determine its value causes additional problems. Hence, attempts to go from the laboratory data to the full scale industrial equipment using this conc ept may end up in failure. This paper starts with the origin of the sp ecific cake resistance in the historical perspective of filtration the ory. Currently used experimental techniques in the determination of sp ecific cake resistance are reviewed, advantages and disadvantages are succinctly summarized. An alternative way of characterization of sludg es using a resistance function rather than a specific cake resistance is proposed.