Abstract
This research was carried out to appreciate a slow sand filtration treatment by an investigation of suspended matter distribution in sand layer at Ashford Common water works, London, UK.and Someya water works, Ueda, Japan.
The following results were obtained.
1) Most of the suspended matter was trapped in the upper layer of the sand bed and remainder, which had penetrated through the surface mud, was also retained in several centimetersdepth from the surface.
2) From the vertical profiles of Chlorophyll/Total Organic Carbon ratio and that of Pheophytin/Total Organic Carbon ratio, there was shown that the matter derived from algae was much easier to enter into the deeper sand layer at Ashford Common water works than at Someyawater works.
3) The order of the decrease rate of the suspended matter in the sand layer was Chlorophyll>Pheophytin>Total Organic Carbon.It could be considered that the decomposition rate in the sand layer varies with the different substance.
