MODELING HINDERED BATCH SETTLING PART I - A MODEL FOR LINKING ZONE SETTLING VELOCITY AND STIRRED SLUDGE VOLUME INDEX

A new type of model for describing the relationship between zone settl ing velocity (V) and stirred sludge volume index (SSVI) is developed. Compared to the earlier studies which link SSVI and V (to reduce multi ple batch tests when collecting X-V, data), the proposed model is more advantageous because it also describes regions of low solids concentr ations. The model is derived from the model for batch settling curve a nd is expressed as v(s)= c(1000X/(X-2 + beta)SSVI-1), where C and beta are parameters describing zone settling velocity and X is the activat ed sludge concentration. The applicability of the relationship was tes ted by analysing data published earlier in the literature. Based on th ese data it was found that the model can be used in wide ranges of SSV I and sludge concentration. A modified Vesilind model is also introduc ed and written as V-s = 1000v/SSVI e(-nX), where n and v are parameter s describing zone settling velocity.