GB190605256A - Improved Filtering Process and Apparatus therefor - Google Patents

Abstract

5256. Bolze, H. March 3. Filters, cleansing. -Filters comprising closed tubes embedded in sand are cleansed by forcing air in the reverse direction through the tubes by means of a column of filtered water, surface sludge being removed by means of a travelling raking-device and a supply of unfiltered water. Impure water is supplied by the pipe 4, and passes over a weir 9<a> in a closed chamber 5, the rate of flow corresponding to the known yield of the filter being indicated on a gauge 6 by a pointer 70. The water enters by a broad spout 10 and the filtrate is discharged by pipes 13, each of which has a turned-up open end fitted with an air cock 26. To cleanse the media, the cock 7 is closed and the cock 26 and discharge cock 24 are opened, admitting air to the pipe 13 and tubes 1. The cocks 26, 23, 24 are then closed and pure water from the pressure main 21 is admitted to an air vessel 17, having an air cock 20 so that air is forced along the pipes 16, 13 and out of the tubes 1, stirring up the surface sludge. When the cock 22 is closed, the cock 7 is fully opened and a truck 34 moving on rails 33 and supporting a rake 36 and a blade 37 is put in reciprocating motion. A wave of turbid liquid is made, the crest of which rises above troughs 30 at the sides so that the sediment is carried away by them and is discharged by a pipe 31. A modified arrangement is shown in Fig. 4. The media are contained in a closed circular chamber. The tubes 1 communicate through perforations in the false bottom 40 with a space 45, discharge pipe 47, and a main 49 which admits cleansing-water under pressure. Impure water enters through a cock 42, pipe 41, and funnel 44; the turbid cleansing-water is discharged down the pipe 41, and through a oock 51. The rake 59 is rotated by bevel-gearing as shown, the blades 60 being inclined to the rake bar 65 to direct the wave to the centre.