The knowledge of the physical, rheological and hydraulic parameters of sewage is required for proper dimensioning of the technological lines of tubular transportation at sewage plants. The authors investigated sewage sediments that originated at the Varsovian sewage treatment plants. Flow tests of sediments were performed with the tubular system of diameter D=0,0207 m and allowed the determination of rheological and hydraulic profile of the tested medium. The description of rheological behavior of the sediments was based on the three-parameter Herschel-Bulkley's model as a function of mass concentration cs. The authors suggested usage of the dimensionless criterion λ(Regen) as a base for pipelines design. ...
Samples of excess sludge from wastewater treatment plants were investiga-ted in order to determine the dependence of rheological parameters of sewage sludge on lime addition. Hydration of the sludge is one of its main features which determine sludge management and waste disposal cost. The rheological behavior of sludge is a key characteristic, since it determines the treatment processes. This research has evaluated the use of rheological properties for characterization and control of sludge and lime mixture flow behaviour. A laboratory investigation was conducted using rotating coaxial cylinder and several different gravimetric on-centrations of the investigated sludge. In order to describe the rheological charac-teristics, the 3-parameter Herschel-Bulkley model was applied. Rheological cha-racterization is of great importance in sludge management, both in terms of biomass dewatering and stabilizing properties, and in terms of design parameters for sludge handling operations.
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