Patent EA-001974-B1 (EA)
Title: Upflow sludge blanket filtering plant for treating drinking plant
Inventor: EPPLER DIETER
IPC: C02F1/52
Filed: 1998-08-25
Abstract: 1. An upflow sludge blanket filtering plant for separating particulate impurities from the raw water being treated and having at least one funnel-like narrowing downward reactor vessel (10) with a raw water supply channel (11) situated in the base area and a clarified water channel (14) in the top area by which means the water from which the particulate impurities have essentially been separated can be drained from the reactor vessel (10), a sludge drainage channel (17) situated at a distance from the base of the reactor vessel (10), by which means sludge which collects in the base area of the reactor vessel can be drained from the reactor vessel (10), a device for creating a negative jump of velocity in the raw water moving upstream in the reactor vessel and containing the particulate impurities, said device for creating a negative jump of velocity is designed so as to form a boundary layer (19) between the upflow raw water flow containing some impurities and moving above it an upflow stream of clarified water, wherein a device (15) is provided in the zone of boundary layer (19) between the sludge drainage channel (17) and the clarified water channel (14) for draining water which may still contain some impurities from the zone which is below the boundary layer (19) and for conducting a partial flow back into the raw water supply channel (11). 2. The filtering plant as claimed in claim 1, wherein the sludge drainage channel (17) is situated at about 1/4 - 1/2 of the reactor height, preferably at 1/3 height. 3. The filtering plant as claimed in claim 1 or 2, wherein the device (15) for discharging of draining water containing some impurities is situated directly above the sludge drainage channel (17), preferably at a half height of the reactor (10). 4. The filtering plant as claimed in any of the preceding claims, wherein a gage is provided for regulating discharges of partially raw water for conducting a partial flow back into the raw water supply channel. 5. The filtering plant as claimed in any of the preceding claims, wherein a pump (18) is connected to the sludge drainage channel (17) for draining the sludge. 6. The filtering plant as claimed in claim 1, wherein the pump (18) for draining the sludge is adopted to use a timer for its on/off operations. 7. The filtering plant as claimed in any of the preceding claims, wherein a valve is provided to regulate and to limit the sludge discharge. 8. The filtering plant as claimed in claim 7, wherein a device is provided to determine the level of the boundary layer (19) between the clarified and the sludge water and is connected to the sludge discharge valve. 9. The filtering plant as claimed in any of the preceding claims, wherein the reactor vessel (10) is round. 10. The filtering plant as claimed in any of the preceding claims, wherein the plant is designed for use at a step of water clarifying in a water treatment plant instead of a secondary sewage tank. 11. A process for separating particulate impurities from the raw water being treated the process is performed in a water clarifying unit as claimed in any of the preceding claims, wherein a negative jump of velocity is created in the upflow raw water stream thus forming a boundary layer (19) between the upflow raw water flow containing some impurities and moving above it an upflow stream of clarified water, wherein the clarified water is drained at a point situated above the boundary layer (19) and the sludge collected in the bottom part of the reactor vessel is drained at a point situated below the boundary layer (19), wherein part of partially sludge water is drained at a point situated directly below the boundary layer (19), and fed it again to the bottom part of the reactor vessel (10) and setting a definite specific discharge of partially sludge water drained as said partial stream for partial flow back, a negative jump of velocity is created in the upflow water stream from the reactor vessel bottom resulting in forming a distinct boundary layer at a predetermined distance from the reactor vessel bottom. 12. The filtering plant as claimed in claim 11, wherein the specific water discharge drained as partial stream for partial flow back is 10 to 20%, preferably about 15% from the specific discharge of inflowing raw water. 13. The filtering plant as claimed in claims 11 or 12 or in combination with claim 6, wherein the pump (18) for sludge draining is operated by a timer started at predetermined time, preferably once a day, and for a predetermined span of time, for instance 1 hour. 14. The filtering plant as claimed in claims 11 or 12 or in combination with claim 7, wherein the sludge is drained at a constant specific water consumption. 15. The filtering plant as claimed in claims 11 or 12 or in combination with claim 8, wherein the sludge discharge valve is controlled by a device for determining the level of the boundary layer (19) so as to maintain said boundary layer at a constant level. 16. The filtering plant as claimed in any of claims 11 to 15, wherein when the specific water discharge drained as partial stream for partial flow back is changing, the specific water consumption of raw water inflowing to the reactor vessel is automatically readjusted and vise versa.