Evaluation of high rate sedimentation lab-scale tank performance in drinking water treatment

Abstract

The Cornell University AguaClara program researches ways to improve the process of potable water treatment at low cost and no energy dependent. A High Rate  Sedimentation (HRS) process that uses upward flow and less area than traditional tanks was investigated. The objective was to analyze parameters affecting HRS tank performance including velocity, density of the floc blanket and location of plate settlers in a laboratory scale HRS tank. Different velocities were set during the experiment, and the resulting performance of the floc blanket was evaluated through continuous turbidity measurements. Results demonstrated that the lab-scale tank allows the creation of a floc blanket and is a versatile design with constraints of visibility and accessibility. In addition, performance of the sedimentation tank improves at lower up flow velocities; however, the study suggests that plate settlers at the top of the tank stabilized the floc blanket at higher velocities, as a consequence of denser floc blankets created by the plates.