Relationships between sludge specific resistance, coefficient of compressibility, blinding coefficient and vacuum filter yield

Abstract

The relationships between an activated sludge's particle size distribution and its specific resistance were investigated. Particle size distributions were rearranged by sludge storage, replacing sludge supernatant with alum sludge supernatant, and by polymer conditioning. Specific resistance was found to increase with decreasing mean particle size. The blinding coefficient (B) was used to show the influence of mean particle size on filter cloth blinding. Blinding was shown to occur only for mean diameters less than 40u. The use of the blinding coefficient also allowed the prediction of maximum and minimum values of specific resistance and showed blinded sludges to have underestimated specific resistance values. The coefficient of compressibility was shown to decrease with increasing mean particle size. The use of the coefficient of compressibility to predict vacuum filter yield was shown to be a valid relationship.