2020 Volume 76 Issue 2 Pages I_1291-I_1296
After a rain event in urban rivers receiving combined sewage outflows, organic sludge (OS) can float on water surface as scum, causing foul odor and worsening the riverscape. Addressing these problems requires first to characterize the physical behavior of OS. In this study, physical properties and characteristics of erosion and deposition of OS were examined by riverbed cross-sectional survey, physical tests of sediment and scum, and one-dimensional simulation of unsteady flow in the Shakujii River estuary.
The scum generated in the estuary has dry density of 1,760 kg/m3, where its main source is considered to be the OS containing large amount plant materials with ignition loss of 28 % or more. In addition, it was found that scum hardly occurs after floods causing maximum tractive force of 2.0 - 2.5 N/m2 or more. These floods cause largely to erode accumulated OS on the riverbed and inhibit the deposition of organic matters sourced from upstream.
PROCEEDINGS OF HYDRAULIC ENGINEERING
