Analysis of Gravity Filtration Behaviors of Waterworks Sludge Based upon Sedimentation Tests

Both gravity filtration experiments under constant pressure conditions and gravity sedimentation experiments were conducted using the municipal waterworks sludge. It was clarified from the theoretical analysis that the effect of sedimentation on the filtration rate was noticeable for the sludge used in this study. The local specific flow resistance at various sludge concentrations was determined by the sedimentation velocity method. The local porosity was related to the local solid compressive pressure by the sedimentation equilibrium method. The decline behaviors in the filtration rate in gravity filtration accompanied by sedimentation were well evaluated only from the sedimentation data based upon the sedimentation velocity method and the sedimentation equilibrium method.