Depth Distribution of Suspended Matter in the Sand Layer of Slow Sand Filters that Take the Surface River Water

Abstract

This research was carried out toappreciate a slow sand filtration treatment by an investigation of suspended matter distribution in sand beds. The following results were obtained.
1) Most of the suspended matter was trapped in the upper layer of the sand bed and the remainder, which hadpenetrated through the surface mud, was also retained in several centimeters depth from the surface.
2) Vertical profiles of suspended matter in the sand bed in long filter run was similar as those in the normal filter run.
3) From the vertical profiles of Chlorophyll / Total Organic Carbon ratio and that of Pheophytin / Total Organic Carbon ratio, there was shown that the algal matter could be entered into the deeper layer at Ishifune water works than Someya ones.
4) The decrease rate order of the suspended matter in the sand bed was Chlorophyll > Pheophytin > Total Organic Carbon. It could be considered that the decomposition rate in the sand layer varied with the different substance.