RELATIONSHIP BETWEEN SLUDGE DEWATERABILITY NUMBER AND CARMAN'S SPECIFIC RESISTANCE

Abstract

A representative of a sludge sample collected from the same source was filtered under the same environmental condition and the result analysed with two different concepts. One method of analysis uses Sludge Dewaterability Number, while the second employed the Carman's Specific resistance concept in sludge filterability. Two plots are employed, one shows a process of specific resistance determination while the other indicates how Sludge dewaterability number can be determined. A critical examination of the two plots reveals that a relationship might exist between the two concepts. Also, the analysis of the filtration results obtained using both the old and the new concepts, confirms that both Sludge Dewaterability Number values and the Specific resistance values decrease with an increase in the conditioner dosages. This is a mark of good coagulation with an increased filterability when conditioner dosages (ferric chloride) are increased in filtration process. The new equations have therefore shown some good relationships between sludge dewaterability number and specific resistance, which are in line with the original concepts. It has also been shown that sludge dewaterability number is directly proportional to the area of filtration and the square root of the specific resistance. This varies according to the diameter of the filtrate collecting cylinder and the area of filtration that is used in the determination of specific resistance (r) values.


Key words: Sludge, Coagulant, Coagulation &Filtration, Sludge Dewaterability Number, and Specific Resistance,


[Global Jnl Engineering Res. Vol.1(2) 2002: 119-126]