The Activated Sludge Flow Characteristics Required for The Design Of Pressure Pipeline

Abstract

In This research studied the effect of the sludge characteristics such as settling propertiese and concentration of solids in the sludge on the flow propertiese of heterogeneous sewage sludges. The non-Newtonian (pseudoplastic ) and time-dependent (thixotropic) influence on the rheological characteristics of sewage sludge was calculated experimentally. Depending on these characteristics and during several experiments an empirical method has been developed to calculate the head losses in pressure pipes which convey these sludges under laminar flow conditions. The results showed that the torque (T) and shear stress (τ) decrease with time at constant rotational speed,and the time-independent behaviour was approached after 900sec.,where no further decrease in shear stress was observed after 900s. A relations has been plotted between the flow rate (Q) and maximum,minimum head losses by means of a design example , in addition to the head loss gradient decay along a pipeline and between Euler and Reynolds numbers .