GB2239269A - Syphon arrangement suitable for dosing a filter in a sewage treatment plant - Google Patents

Abstract

In a dosing system for sewage or other liquid consisting of one or more syphons delivering liquid to or withdrawing liquid from a chamber, the syphons are primed and broken by the controlled operation of valves which connect the syphon to a source of vacuum or admit air. A syphon arrangement, for example for dosing a filter in a sewage treatment plant, has a chamber 43 to which a syphon 42 delivers and from which a syphon 46 withdraws. The syphons 42, 46 are connected to an exhauster 44 for priming, and a control unit 45 controls the operation of valves 51, 52 to control the priming and breaking of the syphons. In another arrangement a syphon has two air inlet pipes having inlets at different levels and a unit controls the operation of one inlet pipe and the priming and breaking of the syphon. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO SYPHONS AND TREATMENT SYSTEMS This invention relates to syphons and treatment systems incorporating one or more syphons.

From one aspect the invention provides a syphon arrangement having pressure-reducing means for priming the syphon, and means for connecting the syphon to the pressure-reducing means in a controlled periodic manner.

There may be valve means operable for breaking the syphon, and means for operating the valve means.

The syphon arrangement may comprise a first syphon delivering to a first chamber and a second syphon having an input in the first chamber, the syphons being connected to the pressure-reducing means in a controlled manner.

There may be first and second valve means respectively operatively connected to the first and second valves for breaking the respective syphon, and means for operating the first and second valve means in a controlled manner.

The level of the second syphon input may be adjustable.

The syphon may have a first air inlet pipe having an inlet at a first level and a second air inlet pipe having an inlet at a higher level than the first level, and valve means for connecting the syphon down pipe to either the first or second air inlet pipes.

There may be control means for priming the syphon and for operating the valve means.

From another aspect the invention provides a syphon having a down pipe, a first air inlet pipe having an inlet at a first level, a second air inlet pipe having an inlet at a higher level than the first level, valve means for connecting the second air inlet pipe to the down pipe, and means for priming the syphon.

There may be means for breaking the syphon.

Conveniently the priming means comprises pressurereducing means and valve means for connecting the pressure-reducing means to the syphon, and the breaking means comprises valve means for the admission of air.

There may be a plurality of syphon arrangements operatively associated for operation in a predetermined order.

The syphon arrangements may be respectively associated with a plurality of chambers to which liquid is delivered by the respective arrangement.

The chambers may form part of a sewage treatment plant. From a further aspect the invention provides a method of controlling the rate of flow of liquid through a syphon to a treatment device comprising priming the syphon in a controlled periodic manner.

The invention relay be performed in various ways and some specific embodiments with possible modifications will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a schematic view of a filter system for a sewage treatment 'plant; X . 2 is a diagrammatic view of one self priming syphon modified to a vacuum primed syphon; Fig. 3 is a diagrammatic view of a self-priming syphon modified by the addition of a vacuum-primed syphon; Fig. 4 shows an operating sequence of the filter system; Fig. 5 shows one arrangement; and Fig. 6 shows another arrangement.

Self priming syphons have been used for many years for dosing in rotation percolatinb filters in sewage treatment works via distributors.

A syphon requires a certain minimum range of level variation in order to prime satisfactorily. The range needed depends in part on the dead space in the seal pipework and hence this pipework is made small in diameter. As a result it is prone to get blocked with grease and may require frequent cleaning. This level variation results in a reducing rate of flow to the distributor(s) as the water level in the syphon chamber drops.

As the level drops the rate of flow of sewage to the filters falls and at certain rates of inflow an equilibrium may be established in which the incoming flow is too high to allow the liquid level to fall to a point at which the syphon will break and at the same time the flow to the filters is too lo to ensure rotation of the filter arms.

In the present arrangemetlt there is controlled priming and breaking in turn of each of a plurality of syphons. Each syphon is primed by the operation of a valve 100 which connects the syphon to an exhauster 101. The syphon is broken either by a fcall of the level of liquid in the well 132 from which the syphon draws or by a valve. At low sewage flows into the well 102 the syphon is broken by the uncovering of an air-inlet or dip-pipe 99. At higher flows the syphon is broken by the operation of a valve 103 which connects the syphon to a second dip-pipe 104 at a higher liquid level. This is illustrated in Fig. 6.

Both operations take place in response to signals from a control unit with operating levels being adjusted to suit individual locations. In maximum flow conditions the syphon-breaking control impulses would be interrupted so the syphons would not be broken until the writer (sewage) level fell again.

Referring to Fig. 1 a filter system 10 at asewage treatment plant or vlorks may coniprise four percolating filters 11, 12, 13, 14 which are arranged to be dosed, that is supplied with sewage it is desired to filter, in a desired sequence through respective syphons lla, 12a, 13a, 14a under the control of a unit 15.

Each syphon is provided with a dip-pipe, a valve to connect it to a source of vacuum and a second valve which connects it to the second dip pipe referred to above. In the case of Fig. 2 the primer llb has a pipe 16 secured to the top of the self-priming syphon bell and communicating with the interior, and a chamber 17.

A non-return valve 18 is in pipe 16 and an electrically operated multi-stage exhaust fan 19 is arranged when driven to reduce the air pressure in the primer chamber 17. The valve 18 is normally closed but can be opened by a control signal from unit 15. The fan is controlled from unit 15.

The fOn may run continuously or intermittently as desired. The non-return valve would maintain the syphon lla until opened by a second electrical impulse.

The operating range may be set so theft the system works within the normal range of the syphons lla to 14a and so that in the event of the power failing the existing syphons operate.

Fig. 4 illustrates a possible sequence of operation. Lines 30 indicate possible periods in which the respective filters are dosed; thus more than one filter can be dosed at any one time.

At low flow the filters can be dosed in sequence; at medium flow the filters are dosed in sequence, two being dosed at any one time; at high flow all filters can be dosed continuously.

Fig. 5 shows another application in which vacuum primed syphons are used to deliver an accurately controlled flow to one of a number of treatment systems operating in parallel. A chamber 40 receives sewage liquid at 41 and a suitable overflow 39 maintains the liquid level constant in chamber 40.

A syphon 42 delivers from chamber 40 to a chamber 43 under the control of a three-way solenoid valve 52 complected to an exhauster 44 under the control of a control unit 45. Operation of the valve 52 makes the syphon so that liquid from chamber 40 is transferred to chamber 43, eventually overflowing through overflow 49.

After a preset adjustable period determined by unit 45 valve 52 is released, admitting air and breaking the syphon. The level of liquid in chamber 43 then falls during a period of stabilization to a level determined by the level of overflow 49. Solenoid valve 51 is then operated by unit 45 and syphon 46 is made, syphoning liquid from chamber 43 into chamber 47 and outlet 48.

The position of the botton of the legs of syphon 46 within chamber 43 is adjustable using movable sleeve 50 and the syphon 46 is broken when the level 53 of liquid in chamber 43 falls to this point. The amount delivered to outlet 48 each cycle is determined by the effective area of cross section of chamber 43 and the operating levels. After a preset time, prior to the operation of valve 52, solenoid valve 51 is released after which the cycle is repeated. The number and size of the syphon arrangements is in accordance with anticipated volume requirements.

There may be a plurality of pairs of syphons of the kind shown in Fig. 5 operated in sequence using a single exhaust device connected to operate the syphons 42 in sequence.

The measured or predetermined volumes from chamber 43 may be delivered to separate receiving chambers.

Claims (17)

1. A syphon arrangement having pressure-reducing means for priming the syphon, and means for connecting the syphon to the pressure-reducing means in controlled periodic manner.

2. A syphon arrangement as claimed in claim 1, including valve means operable for breaking the syphon, and means for operating the valve means.

3. A syphon arrangement as claimed in claim 1 or claim 2, comprising a first syphon delivering to a first chamber, and a second syphon having an input in the first chamber, the syphons being connected to the pressure-reducing means in a controlled manner.

4. A syphon arrangement as claimed in claim 3, comprising first and second valve means respectively operatively connected to the first and second valves for breaking the respective syphon, and means for operating the first and second valve means in a controlled manner.

5. A syphon arrangement as claimed in claim 3 or claim 4, in which the level of the second syphon input is adjustable.

6. A syphon arrangement as claimed in claim 1 or claim 2, in which the syphon has a first air inlet pipe having an inlet at a first level and a second air inlet pipe having an inlet at a higher level than the first level, and valve means for connecting the syphon down pipe to either the first or second air inlet pipes.

7. An arrangement as claimed in claim 6 including control means for priming the syphon and for operating the valve means.

8. A syphon arrangement comprising a syphon having a down pipe, a first air inlet pipe having an inlet at a first level, a second air inlet pipe having an inlet at a higher level than the first level, valve means for connecting the second air inlet pipe to the down pipe, and means for priming the syphon.

9. A syphon arrangement as claimed in claim 8, including means for breaking the syphon.

10. A syphon arrangement as claimed in claim 9, in which the priming means comprises pressure-reducing means and valve means for connecting the pressurereducing means to the syphon, and the breaking means comprises valve means for the admission of air.

11. A plurality of syphon arrangements as claimed in any preceding claim, operatively associated for operation in a predetermined order.

12. A plurality of syphon arrangements as claimed in claim 11, in which the syphon arrangements are respectively associated with a plurality of chambers to which liquid is delivered by the respective arrangement.

13. A plurality of syphon arrangements as claimed in claim 12, in which the chambers form part of a sewage treatment plant.

14. A method of controlling the rate of flow of liquid through a syphon to a treatment device comprising priming the syphon in a controlled periodic manner.

15. A method as claimed in claim 14, including breaking the syphon.

16. A method of controlling the rate of flow of liquid through a syphon to a treatment device substantially as hereinbefore described.

17. A syphon arrangement substantially as hereinbefore described with reference to and as shown in Fig. 5, or Fig. 6, of the accompanying drawings.