AU674511B2 - Waste water treatment system - Google Patents

Description

P/00/009 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Actual Inventor(s): Address for Service: Invention Title: Cv~-o( Pt/ L-t8 MALCOLM LESLIE CLOSE P-B h- AXWE-ErL--&--A-SSeC-1AT-E R at en- a d e ,M.a rk-Att o ey.

Bank Hou-se r 25~5-Aela-4ide Street I.

BRISBANJE -QLD 4000- %k',SQCk-e (GPO Box 3125, BRISBANE, 4001) "WASTE WATER TREATMENT SYSTEM" Details of Associated p Provisional Application: No: PL2l6l, filed 29 _Ajp 1992 Vtj

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The following statement is a fullde ip, invention, including the best method of peforming it known to us: THIS INVENTION relates to a waste water treatment system and in particular to a waste water treatment plant and process particularly suitable for domestic application.

Domestic waste water and human waste is usually disposed of via the public sewerage reticulation system which is connected to a municipal treatment plant or in remote areas by the use of local septic tanks. A septic tank uses anaerobic bacteria to break down solids in the waste. A disadvantage with septic tanks is that they can produce unwanted odours, can have drainage problems and require regular de-sludging.

One alternative system that has been proposed employs a combination of anaerobic and aerobic treatment. This system uses a tank having four separate chambers, the first chamber accomplishes a septic treatment stage on incoming waste wauer and sewerage, the second chamber accomplishes an aerobic treatment stage, the third chamber accomplishes a clarification of the effluent from the second chamber by allowing the effluent to settle and relatively clear effluent drawn off from the third chamber is further clarified and chlorinated in the final chamber where it is stored prior to o being pumped away for irrigation purposes. This system suffers from a number of disadvantages including, firstly it can suffer from similar problems normally associated with the septic tank due to the septic treatment stage and furthermore, the multi-chamber construction gives rise to liquid level variations between chambers and as a consequence, non-uniform stresses arise when the tank is 3 placed in the ground.

It is an object of the present invention to alleviate at least to some degree the aforementioned problems associated with the prior art.

In one aspect therefore, the present invention resides in a waste treatment system for cyclic treatment of waste water including digestible organic waste comprising a tank having an aerobic treatment chamber for holding a supply of waste water, an effluent storage chamber, means for aerating the organic waste in the aerobic treatment chamber and a decanter for decanting effluent from the aerobic treatment chamber to the effluent storage chamber during a decanting phase, the decanter comprising a float connectable to a source of compressed air, a venting means for allowing air to escape from the float; an inlet for the waste water; an outlet for the effluent and a controller to initiate periodic aeration of the waste water following a decanting phase.

20 In a further aspect, the invention resides in a floating decanter suitable for decanting relatively clear .effluent from above settled solids in a waste water treatment S:20006A/703 plant comprising a float connectable to a source compressed air and including venting means for allowing air to escape from the float and a discharge tube adapted to decait the effluent whereby release of air through the venting means sinks the decanter to a predetermined depth whereupon effluent flows into the discharge tube.

Preferably the decanter is operated so that it cycles between raised and sunken positions. The decanter is preferably connected to a chlorinator so that the decanted effluent is chlorinated on route to say the effluent storage chamber of the treatment plant. Preferably, the decanter includes a baffle surrounding an inlet so that surface scum is not decanted when the decanter is in the sunken position.

The tank can be any shape but preferably is generally oooo square or rectangular to allow simple and cheap construction.

Alternatively, an aerobic treatment chamber having an arcuate inside wall which promotes circulation of the organic wast-3 within the chamber so that the lower part of the chamber is Ge Go ball-like can be provided. The effluent storage chamber is preferably separated from the aerobic treatment chamber by a partition bridging across and forming a common wall between oe 0 the aerobic treatment chamber and the effluent storage chamber.

S"Advantageously, the tank includes an inlet adapted to preferentially deliver incoming waste to the bottom of the chamber to stop any short circuiting while the decanter is operating. Advantageously, the inlet comprises a baffle adjacent an opening to the interior of the chamber, the baffle extending from an upper region of the chamber to the lower part of the chamber so that incoming waste flows to the lower part of the chamber.

The controller preferably operates to cycle the plant through a cycle involving three phases, an aeration phase, a settling phase followed by a decanting phase whereafter the cycle recommences with the aeration phase. In order to achieve this, the plant preferably includes a compressor connected via an air supply line to an air diffuser in the lower part of the aerobic treatment chamber. Advantageously, the float of the decanter is coupled to the air supply line to the diffuser by a one way valve so that during the aeration phase, the air delivered to the float serves to move the float to its raised position to prevent decanting. When the aeration phase is completed, there is allowed a o sedimentation period. Once the delivery of air to the decanter is stopped, it remains in the raised position until completion of the sedimentation period. The decanter then 00 00 o moves to the sunken position as air is vented from the float via a solenoid actuated vent. The decanter then draws off clarified effluent which is delivered to the effluent storage chamber through a chlorinator. The controller also controls operation of a pump which is in communication with the S" chlorinated effluent in the effluent storage chamber so that the chlorinated effluent can be discharged from the plant for irrigation purposes.

In order that the present invention can be more readily understood and be put into practical effect, reference will now be made to the accompanying drawings and wherein:- Figures i, 2 and 3 are respective side, plan and elevation section views illustrating a plant according to the present invention; Figure 4 is a pictorial view illustrating a preferred decanter according to the present invention; Figure 5 is a pictorial cut-away view illustrating a chlorinator suitable for use with the present invention; and Figures 6, 7 and 8 are respective side, plan and elevation section views illustrating an alternative embodiment of the present invention.

Referring to the drawings and initially to Figures 1 to 3, there is illustrated a waste water treatment system including a plant 10 comprising a tank 11 having an aerobic treatment chamber 12, an effluent storage chamber 13, a decanter 14 for decanting effluent from the aerobic treatment chamber and delivering same to the effluent storage chamber and a controller 15 for periodically aerating the organic waste and the aerobic chamber 12 through operation of a 0 0*° compressor i6 delivering air to a diffuser 17 along a pipe 18. In the illustrated embodiment, air is delivered e 0 periodically to the aerobic treatment chamber whereafter the waste in the treatment chamber is allowed to settle and then the upper layer of relatively clear effluent is discharged via the decanter 14 into the effluent storage chamber 13.

The tank 11 includes an inlet 19 which delivers untreated waste water and sewerage into the tank. In order to prevent the incoming waste water and sewerage interfering with the decantation process, baffle 20 is employed so that incoming effluent is preferentially delivered beyond the edge of the baffle at 21 and to the lower part of the chamber 12.

A chlorinator 22 includes a refillable storage tube 22a in which chlorine tablets can be stacked and being gradually dissolved in turn as effluent passes through the tablets in the chlorinator 22. An outlet pump 23 is employed to draw off chlorinated effluent from the effluent storage chamber 13 via pipe 13a and deliver it via outlet 24 for irrigation purposes and so forth.

Referring to Figure 3, the effluent storage chamber is defined by a generally circular partition 25 bridging across and forming a common wall between the effluent storage chamber and the aerobic treatment chamber.

Other features illustrated in Figures 1 to 3 include an air grill 26, a liquid level alarm box 27 for monitorina liquid level within the chamber 12 and setting off an alarm in adverse circumstances, an overflow pipe 28 and a process control timer for initiating the various phases of the treatment cycle.

Figure 4 illustrates in more detail the decanter 14 and 0 as can be seen, the decanter 14 is connected to the S"chlorinator (see Figure 5) via a flexible hose portion 29 so S" that the decanter can move between its ,aised and sunken positions. In the illustrated embodiment, the decanter includes a float 30, a discharge tube 31 having an inlet 32 disposed beneath a baffle 33 which prevents scum on the surface of the aerobic treatment chamber from entering the 8 inlet 32 and being decanted into the effluent storage chamber. Compressed air is delivered to the float 30 via a tube 34 and a one way valve (not shown) and liquid can enter the decanter via ball valve chamber 35. The chamber includes a ball valve 36 so that when the float is inflated, the ball valve 36 prevents exit of air from the float through the chamber 35. Thus, when air is pumped into the float 30, the float is purged of liquid and inlet 32 is raised above the liquid in the treatment chamber. When air is turned off, due to the one way valve, the float remains in the raised position until vented via a solenoid controlled vent valve (not shown) downstream of the one way valve whereafter the float fills and decantation commences automatically. The vent valve is opened after a predetermined settling period. In order to limit the depth to which the float sinks, the tube 34 delivers air through an air port 37 set at a predetermined distance from the upper surface 38 of the float so that air vented through the tube p• 34 will only vent until such stage as the liquid level in the float rises through the tube 35 up to the port 37. Thus, decanting will always take place from a predetermined depth below the upper surface of the waste contained in the aerobic treatment chamber.

0* 0 Referring to Figure 5, there is illustrated a typical chlorinator 22 suitable for implementation with the present invention. As can be seen, the chlorinator 22 includes a chlorine tablet storage tube 22a at the base of which there is a V notch 36 (shown in insert) and adjacent the outlet end of the chlorinator 22 is a weir 39 (shown in cutaway) having a V notch 38 thus, enabling a build up of effluent to promote chlorination of the effluent as it passes through the hlorinator.

In the illustrated embodiment, the plant 10 is designed for a five person household giving an average effluent throughput of 1.2m 3 per day. The total tank volume is 7.24m 3 with a working volume of 4.52m 3 and a storage volume of 2.72m 3 in the event of electrical failure. Due to the aerobic treatment involved and the operation of the plant, the applicant has found that a very small amount of sludge is generated and in the main, de-sludging is not required.

Referring now to Figs. 6-8, a generally rectangular o tank 11 has been used to minimize fabrication costs. As the S"system works in generally the same way as that illustrated in Figs. 1-3 the same numerals have been used to label similar features.

It can be seen, particularly in Fig. 8, that a mixing vane 41 is positioned on the base of the tank 11 to enhance mixing of the organic matter and to avoid "dead spots" in the rectangular tank. This embodiment also includes a sludge holding compartment 42. As the waste water circulates o through the aerobic chamber 12 some of the solid matter enters the sludge holding compartment 42 through weir 43 and is trapped therein. Weir 43 is opened with handle 44 it if is desired to trap some of the solid waste in this way for subsequent disposal. Access to the tavk 11 can be gained via manhole 40. Fig. 6 also illustrates the maximum fill level by line A-A.

Whilst the above has been given by way of illustrative example of the present invention, many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as herein set forth.

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Claims (9)

1. A waste treatment system for cyclic treatment of waste water including digestible organic waste comprising a tank having an aerobic treatment chamber for holding a supply of waste water, an effluent storage chamber, means for aerating the organic waste in the aerobic treatment chamber and a decanter for decanting effluent from the aerobic treatment chamber to the effluent storage chamber during a decanting phase, the decanter comprising a float connectable to a source of compressed air, a venting means for allowing air to escape from the float; an inlet for ne waste water; an outlet for the effluent and a controller to initiate periodic aeration of the waste water following a decanting phase.

2. A waste water treatment system as claimed in claim 1, wherein a discharge tube mounted on the float in '"*fluid communication with the aerobic treatment chamber and the effluent storage chamber whereby release or air througch the venting means allows the decanter to move S 20 into the sunken position whereupon effluent flows into the discharge tube from the aerobic treatment chamber.

3. A waste water treatment system as claimed in claim 2, wherein the venting means comprises a solenoid- actuated valve which is opened by the controller to start 25 the decanting phase.

4. A waste water treatment system according to any one of claims 1 to 3, further comprising a chlorinator.

A waste treatment system according to claim 4, wherein the chlorinator comprises an upwardly-exLending tube in which chlorine tablets can be stacked, said tube being in fluid communication with the discharge tube at its outlet into the effluent storage chamber whereby the chlorine tablets are grauually dissolved as effluent flows into the effluent storage chamber.

6. A waste treatment system as claimed in any one of claims 1 to 5, wherein the aerobic treatment chamber is generally square or rectangular and includes at least one mixing vane protruding from the floor of the aerobic S;20006A1703 12 treatment chamber to promote mixing of organic waste.

7. A waste treatment system as claimed in any one of claims 1 to 5, wherein the aerobic treatment chamber has an arcuate inside wall to promote circulation of the organic waste within the chamber.

8. A floating decanter suitable for decanting relatively clear effluent from above settled solids in a waste water treatment plant comprising a float connectable to a source of compressed air and including venting means for allowing air to escape from the float, and a discharge tube adapted to decant the effluent whereby release of air through the venting means sinks the decanter to a predetermined depth whereupon effluent *e flows into the discharge tube.

9. A process for regeneration of waste water including digestible organic waste comprising, aerating the digestible organic waste for a predetermined period of time in an aerobic treatment chamber, subsequently 2 allowing the aerated waste to settle in the chamber for a 20 predetermined settling time and subsequently decanting relatively clear effluent from the upper layer of the settled waste using a decanter as claimed in claim 8 and chlorinating the decanted effluent while delivering same to a storage chamber and repeating the process on a S• 25 cyclic basis. A waste treatment system substantially as hereinbefore described with reference to the drawings. Dated this 29th day of May 1996 MALCOLM LESLIE CLOSE By his Patent Attorney GRIFFITH HACK CO S:20006A/703 ABSTRACT A waste treatment system for cyclic treatment of waste water including digestible organic waste comprising a tank having an aerobic treatment chamber for holding a supply of waste water, an effluent storage chamber, means for aerating the organic waste in the aerobic treatment chamber and a decanter for decanting effluent from the aerobic treatment chamber to the effluent storage chamber during a decanting phase; an inlet for the waste water; an outlet for the effluent and a controller to initiate periodic aeration of the waste water following a decanting phase. eeel .oe. oe oo o