AU2006207887A1

AU2006207887A1 - Waste water treatment process

Info

Publication number: AU2006207887A1
Application number: AU2006207887A
Authority: AU
Inventors: Malcolm Close
Original assignee: NEATPORT Pty Ltd
Current assignee: NEATPORT Pty Ltd
Priority date: 2005-09-07
Filing date: 2006-09-07
Publication date: 2007-03-22
Anticipated expiration: 2026-09-07
Also published as: AU2006207887B2

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: Neatport Pty Ltd Invention Title: WASTE WATER TREATMENT PROCESS The following statement is a full description of this invention, including the best method of performing it known to me/us: 2

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WASTE WATER TREATMENT PROCESS Field of the Invention SThe present invention relates to waste water treatment processes.

Background of the Invention Waste water treatment processes involving the 00 00 aerobic digestion of organic wastes have been previously proposed for waste waters such as raw sewage which contain high levels of bacteria, which although toxic to human consumption are actually used in the aerobic process to CI breakdown the organic waste. This is achieved by providing the bacteria with oxygen (typically by a source of air) to enable the bacteria to feed off the organic waste.

Summary of the Invention According to a first aspect of the present invention there is provided a process for treating waste water, the process comprising the steps of: collecting the waste water; adding a nutrient dose to the collected waste water; and subjecting the dosed waste water to aerobic digestion.

Preferably, the waste water is a waste water which would be unresponsive to step without first performing step Preferably, the waste water is grey water. Grey water includes waste water from fixtures such as baths, sinks, washing machines, and the like.

Preferably, the step of collecting the waste water occurs in a tank. However, in other embodiments it may be collected in other storage devices such as a pond for example.

Preferably, the step of aerobic digestion occurs in an activated sludge tank. The activated sludge tank H:\Sherylm\Kee\Speci\P62069.doc 7/09/06 3 may or may not be the same tank in which the waste water is collected.

SAccording to a second aspect of the present invention, there is provided a nutrient dose for adding to waste water in a waste water treatment process to enable the growth of bacteria in the waste water, wherein the nutrient dose comprises at least a source of food for the 00 00 bacteria.

Preferably, the source of food comprises a source O 10 of carbon.

SPreferably, the source of carbon is a sugar.

C Preferably, the sugar is glucose.

Preferably, the source of food comprises 0.1-1.0 grams of a source of carbon per litre of waste water, more preferably 0.3-0.7 grams per litre, even more preferably approximately 0.5 grams per litre.

Preferably, the source of food comprises a source of nitrogen.

Preferably, the source of nitrogen is a nitrate.

Preferably, the nitrate is urea.

Preferably, the source of food comprises 0.1-1.0 grams of a source of nitrogen per litre of waste water, more preferably 0.3-0.7 grams per litre, even more preferably approximately 0.5 grams per litre.

Preferably, the nutrient dose also comprises a flocculant.

Preferably, the flocculant is aluminium sulfate.

Preferably, the nutrient dose also comprises 0.1grams of a flocculant per litre of waste water, more preferably 0.3-0.7 grams per litre, even more preferably approximately 0.5 grams per litre.

Brief Description of the Drawings A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a plant for H:\SherylM\Keep\Speci\P62069.doc 7/09/06 4 Scarrying out the waste water treatment process according c to preferred embodiments of the present invention; and SFigure 2 is a schematic view of the plant according to Figure 1.

Detailed Description of Preferred Embodiments Referring to Figure i, a waste water treatment 00 00 plant 10 for carrying out a waste water treatment process according to preferred embodiments of the present invention is shown. The waste water treatment plant Scomprises an aerobic treatment chamber 11 and an effluent Cl storage tank 12, shown in Figure 1 located inside the aerobic treatment chamber 11 for compactness of the plant The plant also comprises a floating decanter 13 which transfers treated effluent via a chlorinator 14 from the aerobic treatment chamber 11 into the effluent storage chamber 12. The floating decanter 13 operates similarly to the decanter described in the Applicant's own patent AU 674511.

The treatment plant 10 further comprises a motor box 15 which drives an air blower 16 for periodically reaerating the waste water in the aerobic treatment chamber 11. An air diffuser 17 at the base of the aerobic treatment chamber 11 distributes the air through the waste water.

The waste water treatment plant 10 has an inlet which delivers untreated waste water into the aerobic treatment chamber 11. The waste water delivered to the aerobic treatment chamber 11 enters firstly a stilling well 21 in the treatment chamber 11 in order to prevent the incoming waste water from interfering with the treatment process. In the embodiment shown in Figure i, the stilling well 21 comprises a baffle 22. The baffle 22 is semi-circular in shape with its curvature opposing that of the facing wall of the aerobic treatment chamber 11.

The baffle is slightly spaced away from the wall of the aerobic treatment chamber 11 so the waste water can exit H; \Serylm\Keep\Speci\P62069.doc 7/09/06 5 Sthe stilling well 21 around the sides of the baffle 22.

In an alternative embodiment (not shown) the Sstilling well 21 is a stilling tank, located inside the aerobic treatment chamber 11. Waste water enters the stilling tank through the inlet 20 and a pump at the base of the stilling tank pumps water from the bottom of the stilling tank to exit the stilling tank and enter the 00 00 aerobic treatment chamber 11 towards the top of the stilling tank.

The waste water treatment plant 10 also comprises San effluent outlet 25 from the effluent storage tank 12.

CI Treated effluent is delivered to the effluent outlet 25 by a treated effluent pump 26 located at the bottom of the effluent storage tank 12.

Typically, the waste water treatment plant 10 is utilised to recycle domestic grey water. In this case the waste water treatment plant 10 is located on or near the domestic property or properties for which it is used, with the inlet 20 to the waste water treatment plant connected to the grey water outlet or outlets of the properties and the outlet from the waste water treatment plant 10 connected to the inlet or inlets of those fixtures on the properties that can utilise the treated effluent, such as toilets or sprinkler systems for example.

Referring also to Figure 2, the waste water treatment plant 10 also comprises a float control system 29 for operating the effluent storage tank 12, including a control box 30 for processing and executing the signals used in the float control system 29. The float control system 29 comprises an irrigation float switch 31 and a town water control float switch 32. The float control system 29 as shown Figure 2 may also comprise a pump float switch 33. The irrigation float switch 31 is located towards the top of the effluent storage tank 12 and provides a high water control for the effluent storage tank 12. The irrigation float switch 31 operates to H:\Sherylm\Keep\Spci\P62069 .doC 7/09/06 6 control the level of treated effluent in the effluent storage tank 12 such that when it becomes too high (ie.

Swhen the float switch 31 rises to a specified level in the effluent storage tank 12) it signals the control box 30 to discharge treated effluent from the tank 12. The control box 30 does this by opening a solenoid valve 34 on an irrigation line 35 to discharge treated effluent to a 00 00 sprinkler system.

The town water float switch 32 is located towards the bottom of the effluent storage tank 12 and provides a Slow water control for the effluent storage tank 12. The C1 town water float switch 32 operates to control the level of treated effluent in the effluent storage tank 12 such that when it becomes too low (ie. when the float switch 32 falls to a specified level in the effluent storage tank 12) it signals the control box 30 to flow town water into the effluent storage tank 12 via a town water inlet 36 to the tank 12. Thus, when the demand for treated effluent from the waste water treatment plant 10 exceeds the amount of effluent produced to the extent that the effluent storage tank 12 is going to empty of water, the operation of the town water float switch 32 ensures that town water provides a back up source of water to ensure that there is always a flow of water to meet demand.

The pump float switch 33 is located towards the bottom of the effluent storage tank 12 and operates to control the effluent pump 26 such that when the level of water in the effluent storage tank 12 becomes too low the pump float switch 33 signals the control box to switch off the effluent pump 26.

The process of treating the waste water in the waste water treatment plant 10 generally begins by delivering waste water to the aerobic treatment chamber 11 through the inlet 20 and via the stilling well 21.

Although it is noted that a pre-treatment step may occur if the town water float switch 32 calls for town water to be delivered to the effluent storage tank 12 for use in H: \SherylM\Keep\Spec \P62069.doC 7/09/06 7the fixtures from which the waste water flows to the inlet Once the aerobic treatment chamber 11 has sufficiently filled with waste water, the process of aerobic digestion is "kick-started" by adding a nutrient dose to the waste water. If treating solely grey waste water, it has been conventionally thought that it is not 00 00 possible to treat grey water aerobically. However, by providing this nutrient dose, aerobic digestion is possible because the nutrient dose provides enough Smaterial off which the bacteria required for aerobic C1 digestion can feed.

The nutrient dose comprises at least a source of food for bacteria. The source of food comprises a source of carbon and/or a source of nitrogen, which in a preferred form of the invention are a sugar (glucose) and a nitrate (urea), although any other suitable source of carbon and/or nitrogen may be used. The source of nitrogen is typically required because grey water generally has a large imbalance of phosphates compared to nitrates. Typically grey water has high levels of phosphates due to detergents, washing powders and other cleaning agents being present in the water. The carbon provides a building block for the bacteria population to grow as there is typically very little BOD in grey water.

The nutrient dose may also comprise a flocculant, which in a preferred form of the invention is aluminium sulfate, although any other suitable flocculant may be employed.

The flocculant bonds together the nutrient dose when it is added to the grey water, ie. prevents it from dispersing.

This is so that a significant biomass can build up to enable the aerobic treatment of the waste water. In a preferred form of the invention the nutrient dose added to the waste water comprises each of a source of carbon (preferably glucose), a source of nitrogen (preferably urea) and a flocculant (preferably aluminium sulfate) at 0.1-1.0 grams per litre of waste water (preferably 0.3-0.7 H: \SherylM\Keep\Speci\P62069 .doc 7/09/06 8 grams per litre, more preferably approximately 0.5 grams per litre).

SOnce the nutrient dose has been added to the waste water, air is delivered periodically to the aerobic C 5 treatment chamber 11 whereafter the waste in the treatment chamber 11 is allowed to settle and then the upper layer of relatively clear effluent is discharged via the 00 00 decanter 13 into the effluent storage tank 12. As described above, the treated effluent in the effluent storage tank is subsequently recycled for use in at least Ssome of the fixtures from which the waste water treatment CI plant 10 receives waste water.

Once the process has started and the waste water has had the nutrient dose added, regular nutrient dosing is not required as the process is generally selfperpetuating. However, occasional dosing may be required if the aerobic digestion rate decreases sufficiently.

Furthermore, if the process is ever stopped or shut-down, then a nutrient does will be required to be added to the waste water to start the process up again.

In the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, ie. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It is to be clearly understood that although prior art publication(s) are referred to herein, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art in Australia or in any other country.

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Claims

2. A nutrient dose as claimed in claim i, 00 00 wherein the source of food comprises a source of carbon.
3. A nutrient dose as claimed in claim 1, wherein the source of food comprises a source of carbon at 0.1-1.0 grams per litre of waste water. C 4. A nutrient dose as claimed in either claim 2 or 3, wherein the source of carbon is a sugar. A nutrient dose as claimed in claim 4, wherein the sugar is glucose.
6. A nutrient dose as claimed in any of the preceding claims, wherein the source of food comprises a source of nitrogen.
7. A nutrient dose as claimed in any of the preceding claims, wherein the source of food comprises a source of nitrogen at 0.1-1.0 grams per litre of waste water.
8. A nutrient dose as claimed in either claim 6 or 7, wherein the source of nitrogen is a nitrate.
9. A nutrient dose as claimed in claim 8, wherein the nitrate is urea. A nutrient dose as claimed in any of the preceding claims, also comprising a flocculant.
11. A nutrient dose as claimed in any of the preceding claims, wherein the source of food comprises a flocculant at 0.1-1.0 grams per litre of waste water.
12. A nutrient dose as claimed in either claim or 11, wherein the flocculant is aluminium sulfate.
13. A process for treating waste water, the process comprising the steps of: collecting the waste water; adding a nutrient dose to the collected H: \SherylM\Keep\Speci\P62069.doc 7/09/06 10 waste water; and subjecting the dosed waste water to aerobic Sdigestion.
14. A process as claimed in claim 13, wherein the waste water is a waste water which would be unresponsive to step without first performing step 00 00 15. A process as claimed in either claim 13 or Sclaim 14, wherein the step of aerobic digestion occurs in 9 10 an activated sludge tank. O
16. A process as claimed in any one of claims CI 13 to 15, wherein the nutrient dose comprises a nutrient dose according to any one of claims 1 to 12.
17. A nutrient dose as substantially described herein.
18. A process for treating waste water as substantially described herein, with reference to the accompanying drawings. H: \SerylM\KeeP\Speci\P62069.doc 7/09/06