부산대학교 도서관

The maximum limit of water storage capacity in sewers and storm drains depends on the draining capacity of the sewer or drain. When the draining capacity is exceeded, this results in the overloading of the sewer capacity, causing flooding. This moment, which is called the “choking” phenomenon. Therefore, draining capacity will decrease, and flooding can occur in a short period of time. The purpose of the current research was to examine this phenomenon by determining the correlation between draining capacity and water storage levels in the experimental situation. The experiments were based on original techniques published in 1949 [1, 2] which demonstrated an increase in the flow rate in a pipe by adding polymer solution into the fluid in a turbulent flow; this has been termed the “Drag Reduction Effect”. The experiments demonstrated that the addition of the polymer solution proved to reduce the drag between the fluid and the pipe wall, and that the overloaded sewer effect can be relieved by means of polymer addition into the draining system, which enhances draining capacity during flooding situation, To conduct the experiment, an acrylic tank with a capacity of 65 litres was prepared to simulate a flooding area. Three different sizes of polyvinyl chloride (PVC) pipe (10, 18 and 20 millimeters) were used as a test section to simulate a sewer pipe. The experiment was conducted by dosing a gravity pipe flow system with Polyacrylamide (PAM), known as anionic polymer, which is normally employed in wastewater treatment processes, at different concentrations (0, 10, 30, 50, 100 wppm (part per million by weight), The results of the experiment indicate that a suitable amount of polymer addition can increase maximum enhancement of draining capacity up to 13 % and increase maximum flow rate up to 12%. It was also observed that the increased flow rates resulting from the drag reduction phenomenon occurred as an effect of the type of polymer and the concentration of the polymer.