Settling of nutrient removal activated sludges

This paper surveys the settling properties of activated sludges from four biological nutrient removal plants. Empirically derived constants used in the settling flux theory are correlated with more traditional measures of settling properties such as the SVI. An easy method of using the settling flux approach to clarifier design and operation is presented and a new parameter describing the settling properties of sludges is proposed. Typical values of constants describing the settling properties of nutrient removal sludges are presented. It was found that the factor most influencing sludge settling properties was the degree of aeration in these plants.