GB2172216A

GB2172216A - Water treatment plant

Info

Publication number: GB2172216A
Application number: GB08506597A
Authority: GB
Inventors: David Wrigley
Original assignee: CONDOR GROUP PLC
Current assignee: CONDOR GROUP PLC
Priority date: 1985-03-14
Filing date: 1985-03-14
Publication date: 1986-09-17
Also published as: GB2172216B; GB8506597D0

Abstract

Water treatment plant comprises a flocculation chamber 1, a settlement chamber 2 and a filter bed chamber 3 in series. The settlement chamber 2 contains a pack 9 of inclined tube settlers whose left-hand wall defines a widening inlet channel to the chamber. The water flows from the flocculation chamber 1 to the said channel over a weir and subsequently flows horizontally before passing up through the settlers 9. The filter bed 15 is periodically backwashed, and the backwash water flows into trough 20 and back to chamber 2 via one-way flap valves 14, 21 which preclude flow in the opposite direction. This action flushes settled solids in chamber 2 towards outlet 12. <IMAGE>

Description

SPECIFICATION Water treatment plant A first aspect of the present invention provides a water treatment plant comprising a settlement chamber and a filter bed chamber downstream of the settlement chamber, the settlement chamber and the filter bed chamber being intercommunicated by a duct whose communication with the filter bed chamber is below the normal water level in the filter bed chamber, which duct is provided with a mechanically-automatic one-way valve for allowing flow from the filter bed chamber to the settlement chamber but not in the other direction.

The one-way valve may be a flap valve, for instance in a dividing wall between the settlement chamber and the filter bed chamber. The valve opens automatically on draining the settlement chamber to allow filter backwash water and solids removed in it to drain into the settlement chamber and exit along with the sludge from the settlement chamber, thus assisting in cleansing the settlement chamber.

The duct can be connected to a collection trough in the filter bed chamber whose top is below the lowest permitted water level in the filter bed chamber but sufficiently above the filter bed itself not to cause gross interference with the filter bed or gross discharge of filter bed materials.

According to a second aspect of the invention, there is provided a water treatment plant comprising a settlement chamber having an inlet and a diverging duct downstream of the inlet. The diverging duct slows the inlet water velocity and increases the rate of settlement of suspended solids and flocs. The diverging duct can simply be provided by having a wall adjacent the inlet (e.g. adjacent an inlet weir) which is inclined to the vertical and widening taper between itself and an adjacent wall of the settlement chamber-the wall can for instance be the wall of a bank or pack of settlers.

According to a third aspect of the invention, there is provided a water treatment plant comprising a settlement chamber having therein a bed of settlers positioned such that at the inlet end of the bank, the general direction of water flow is at roughly 900 to the settlers. This forces the water to change direction at the inlet end of the bank and increases the rate of settlement of suspended solids. The settlers can be in the form of tubes (settlement tubes).

Any two of the aspects of the invention can be combined together, or all three can be combined together.

An embodiment of the invention will be further described, by way of example, with reference to the accompanying drawing, which is a schematic side view of a water treatment plant.

The plant has a flocculation chamber 1, a settlement (settlement/clarification) chamber 2 and a filter bed chamber 3. An inlet feed pipe 4 is associated with a flow indicator and transmitter 5 for the chemical dosing pump control and is dosed through inlets 6. Flocculation occurs in the flocculation chamber 1, assisted by paddles 7 driven by a motor 8.

The liquor then passes over a weir into the settlement chamber 2 which contains a bank or pack of inclined tube settlers 9. The lefthand wall 10 of the pack 9 is inclined to the vertical to provide a diverging duct downstream of the inlet, the wall 10 being extended vertically upwards to provide a baffle across the chamber 2. Coarse settlement occurs in the widening duct between the lefthand wall of the chamber 2 and the wall 10.

At the bottom of the tank, and inclined an inclined baffle 11 forms a sludge hopper leading to a sludge outlet 12. There is a baffle 13 and a one-way flap valve 14 which allows sludge to slide down the baffle 11 without permitting gross short-circuiting of the pack 9.

The general direction of water flow at the lower, inlet end of the pack 9 is horizontal and is roughly at 900 to the tubes of the pack 9~thus the water flow must change direction as it enters the tubes of the pack 9. The pack 9 clarifies the water. The water then passes over another weir into the filter bed chamber 3 which contains a gravity sand filter 15.

There is a group of level sensors 16 which in effect maintain the level between the lowermost and middle sensors 16 by way of a control 17 and an outlet pump (not shown).

The filtered water passes out through an outlet pipe 18 and can be fit for potable and/or process use, suspended solids having been removed and sometimes colour. There is a backwash inlet pipe 19 for backwashing the filter bed chamber 3, a trough 20 is positioned in the sand filter 15. In order to remove the filter backwash water and the solids in it from the chamber 3 with its top about 400 mm above the top of the sand filter 15 (the chamber 3 being about 3 metres high).

The trough 20 is of T-shape as seen from above, the "cross-bar" being seen in section and the "upright" being seen in side view.

The "upright" leads to a one-way flap valve 21 which allows the water and solids to pass from the trough 20 down the inclined baffle 11, thereby assisting in cleansing the settlement chamber 2. An air scour 22 can be provided if desired.

1. A water treatment plant comprising a settlement chamber and a filter bed chamber downstream of the settlement chamber, the settlement chamber and the filter bed chamber being intercommunicated by a duct whose communication with the filter bed chamber is

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Water treatment plant A first aspect of the present invention provides a water treatment plant comprising a settlement chamber and a filter bed chamber downstream of the settlement chamber, the settlement chamber and the filter bed chamber being intercommunicated by a duct whose communication with the filter bed chamber is below the normal water level in the filter bed chamber, which duct is provided with a mechanically-automatic one-way valve for allowing flow from the filter bed chamber to the settlement chamber but not in the other direction. The one-way valve may be a flap valve, for instance in a dividing wall between the settlement chamber and the filter bed chamber. The valve opens automatically on draining the settlement chamber to allow filter backwash water and solids removed in it to drain into the settlement chamber and exit along with the sludge from the settlement chamber, thus assisting in cleansing the settlement chamber. The duct can be connected to a collection trough in the filter bed chamber whose top is below the lowest permitted water level in the filter bed chamber but sufficiently above the filter bed itself not to cause gross interference with the filter bed or gross discharge of filter bed materials. According to a second aspect of the invention, there is provided a water treatment plant comprising a settlement chamber having an inlet and a diverging duct downstream of the inlet. The diverging duct slows the inlet water velocity and increases the rate of settlement of suspended solids and flocs. The diverging duct can simply be provided by having a wall adjacent the inlet (e.g. adjacent an inlet weir) which is inclined to the vertical and widening taper between itself and an adjacent wall of the settlement chamber-the wall can for instance be the wall of a bank or pack of settlers. According to a third aspect of the invention, there is provided a water treatment plant comprising a settlement chamber having therein a bed of settlers positioned such that at the inlet end of the bank, the general direction of water flow is at roughly 900 to the settlers. This forces the water to change direction at the inlet end of the bank and increases the rate of settlement of suspended solids. The settlers can be in the form of tubes (settlement tubes). Any two of the aspects of the invention can be combined together, or all three can be combined together. An embodiment of the invention will be further described, by way of example, with reference to the accompanying drawing, which is a schematic side view of a water treatment plant. The plant has a flocculation chamber 1, a settlement (settlement/clarification) chamber 2 and a filter bed chamber 3. An inlet feed pipe 4 is associated with a flow indicator and transmitter 5 for the chemical dosing pump control and is dosed through inlets 6. Flocculation occurs in the flocculation chamber 1, assisted by paddles 7 driven by a motor 8. The liquor then passes over a weir into the settlement chamber 2 which contains a bank or pack of inclined tube settlers 9. The lefthand wall 10 of the pack 9 is inclined to the vertical to provide a diverging duct downstream of the inlet, the wall 10 being extended vertically upwards to provide a baffle across the chamber 2. Coarse settlement occurs in the widening duct between the lefthand wall of the chamber 2 and the wall 10. At the bottom of the tank, and inclined an inclined baffle 11 forms a sludge hopper leading to a sludge outlet 12. There is a baffle 13 and a one-way flap valve 14 which allows sludge to slide down the baffle 11 without permitting gross short-circuiting of the pack 9. The general direction of water flow at the lower, inlet end of the pack 9 is horizontal and is roughly at 900 to the tubes of the pack 9~thus the water flow must change direction as it enters the tubes of the pack 9. The pack 9 clarifies the water. The water then passes over another weir into the filter bed chamber 3 which contains a gravity sand filter 15. There is a group of level sensors 16 which in effect maintain the level between the lowermost and middle sensors 16 by way of a control 17 and an outlet pump (not shown). The filtered water passes out through an outlet pipe 18 and can be fit for potable and/or process use, suspended solids having been removed and sometimes colour. There is a backwash inlet pipe 19 for backwashing the filter bed chamber 3, a trough 20 is positioned in the sand filter 15. In order to remove the filter backwash water and the solids in it from the chamber 3 with its top about 400 mm above the top of the sand filter 15 (the chamber 3 being about 3 metres high). The trough 20 is of T-shape as seen from above, the "cross-bar" being seen in section and the "upright" being seen in side view. The "upright" leads to a one-way flap valve 21 which allows the water and solids to pass from the trough 20 down the inclined baffle 11, thereby assisting in cleansing the settlement chamber 2. An air scour 22 can be provided if desired. CLAIMS

1. A water treatment plant comprising a settlement chamber and a filter bed chamber downstream of the settlement chamber, the settlement chamber and the filter bed chamber being intercommunicated by a duct whose communication with the filter bed chamber is below the normal water level of the filter bed chamber, which duct is provided with a mechanically-automatic one-way valve for allowing flow from the filter bed chamber to the settlement chamber but not in the other direction.

2. The plant of Claim 1, when the one-way valve is a flap valve.

3. The plant of Claim 1 or 2, wherein the one-way valve is in a dividing wall between the settlement chamber and the filter bed chamber.

4. The plant of any of the preceding Claims, wherein the duct is connected to a collection trough in the filter bed chamber whose top is below the lowest permitted water level in the filter bed chamber but sufficiently above the filter bed itself not to cause gross interference with the filter bed or gross discharge of filter bed materials.

5. A water treatment plant comprising a settlement chamber having an inlet and a diverging duct downstream of the inlet.

6. The plant of Claim 5, and also in accordance with any of Claims 1 to 4.

7. The plant of Claim 5 or 6, wherein the diverging duct is provided by having a wall adjacent the inlet, which wall is inclined to the vertical and provides a widening taper between itself and an adjacent wall of the settlement chamber.

8. The plant of Claim 7, wherein said wall is adjacent an inlet weir.

9. The plant of Claim 7 or 8, wherein said wall is the wall of a bank or pack of settlers.

10. A water treatment plant comprising a settlement chamber having therein a bank of settlers positioned such that at the inlet end of the bank, the general direction of water flow is at roughly 900 to the settlers.

11. The plant of Claim 10, and also in accordance with any of Claims 1 to 9.

12. The plant of Claim 10 or 11, wherein the settlers are in the form of tubes.

13. A water treatment plant, substantially as herein described with reference to, and as shown in, the accompanying drawing.

14. A water treatment plant having a settlement chamber and a filter bed chamber intercommunicated by a duct in the manner substantially as herein described with reference to, and as shown in, the accompanying drawing.

15. A water treatment plant, having a settlement chamber with an inlet and a diverging duct downstream of the inlet, in the manner substantially as herein described with reference to, and as shown in, the accompanying drawing.

16. A water treatment plant having a bank of settlers in which the flow at the inlet end of the bank is arranged substantially as herein described with reference to, and as shown in, the accompanying drawing.