AU2006207888A1 - Waste water treatment system - Google Patents

Description

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AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: Neatport Pty Ltd Invention Title: WASTE WATER TREATMENT SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 WASTE WATER TREATMENT SYSTEM e, ()Field of the Invention The present invention relates to waste water treatment systems.

00 00 Background of the Invention 00 There are many situations where there is a limited supply of fresh water for human consumption. One \1 0 example of this is on boats; from small yachts carrying a Shandful of people to much larger vessels such as cruise C ships which carry hundreds of people. In these situations, fresh water is required not only for drinking but also for fixtures such as showers, baths, sinks and washing machines for example. Water is also required to flush toilets. However, the toilet flush need not be fresh water and thus, in order to save fresh water in such situations where its supply is limited, an alternative source of water is often used. In many cases, particularly in the case of boats, salt water from the ocean is used to flush the toilet.

The effluent from all of these fixtures is collected as sewage and is subsequently treated in various ways. One method is to send the sewage either directly or in the case of boats, after having been retained in a container until the end of a voyage, to a municipal sewerage system. The difficulty with this method is that it requires the construction and maintenance of significant infrastructure, such as sewerage piping to connect to the municipal sewerage system or the provision of large holding tanks which, particularly in the case of boats, will occupy a large amount of space and also present a health risk if damaged.

Another method, often used in relation to boats, is to "wash" the sewerage in a large container tank with salt water from the ocean prior to its release into the ocean. The washing of the sewerage kills the bacteria and H: \SherylM\Keep\Speci\P62070 SPEC.doc 7/09/06 3 other pathogens present in the sewerage due to the saline conditions and also dilutes the nutrient dosing in the Ssewerage. Nevertheless, this method presents a significant environmental risk because the nutrients are not broken down and also because it requires the use of large holding tanks to store and wash the sewage. For 00 smaller boats, the practice of washing the sewage may not 00 00 occur at all because tanks of the required size cannot be fitted and the sewage is simply released directly into the ocean.

CI Summary of the Invention According to a first aspect of the present invention there is provided a waste water treatment system for treating salt water based waste water, the system comprising at least one activated sludge tank for treating the waste water aerobically and an inlet connected to a conduit from at least one fixture which produces salt water based waste water.

Preferably, the system also comprises an outlet connected to a conduit to at least one of the fixtures to recycle treated effluent from the activated sludge tank to the fixture.

Preferably, the system is the waste water system on a vehicle.

The vehicle may be any motorised or non-motorised transport apparatus such as a car, bus, truck, train caravan, trailer, carriage, barge, boat, ship or other land or marine vessel.

More preferably, the system is on a boat, barge, ship or other marine vessel.

Preferably, the waste water comprises black water and/or grey water.

Black water includes waste water which is contaminated with digestible organic waste including human excrement. Grey water includes waste water containing only mild levels of bacteria and comes from fixtures such as H: \SherylM\Keep\Speci\P62070.SPEC.doc 7/09/06 4 baths, sinks, washing machines, and the like.

Preferably, the at least one fixture is a e( Stoilet, which produces black water.

Preferably, the outlet is connected by the conduit to the toilet. Thus, the treated effluent is used to flush the toilet.

00 Preferably, the at least one fixture also 00 00 comprises grey water producing fixtures such as showers, baths, basins, sinks for example.

Preferably, the waste water treatment system also Scomprises a control means for controlling treatment of the CI waste water in batches.

Preferably, the control means controls treatment of the waste water in a continuous batch process.

Preferably, the waste water treatment system also comprises a primary batching tank for holding the waste water prior to treatment in the at least one activated sludge tank.

Preferably, the waste water treatment system also comprises a treated effluent holding tank for holding the treated effluent from the at least one activated sludge tank.

Treated effluent in the treated effluent holding tank is recycled to the toilet for flushing the toilet.

Excess treated effluent to the capacity of the treated effluent holding tank may be disposed of. This disposal does not pose a significant risk to either human health or the environment because of the quality of the treated effluent.

Preferably, the at least one activated sludge tank comprises at least one treatment cell, more preferably a plurality of treatment cells.

Preferably, each treatment cell is substantially identical.

The advantage of using a plurality of treatment cells is that smaller cells (which occupy less space than one large cell) can be operated in a continuous batch H: \SheryIM\Keep\Speci\P62070. SPEC.doc 7/09/06 5 Sprocess. This is because whilst one cell is filling with c waste water, other cells can operate at various stages of Sthe treatment process.

Preferably, the waste water treatment system also comprises a distribution means for distributing the flow of waste water to each of the plurality of cells.

00 Preferably, the distribution means comprises at 00 00 least one three-way valve.

Preferably, only one of the plurality of C1 0 treatment cells can receive waste water from the primary Sbatching tank at any given time.

CI Preferably, the control means comprises a waste water level detection means in each treatment cell for detecting the waste water level in each of the cells to control the filling, treating, emptying and refilling of the cells.

Preferably, when a first cell is at a specified low level, the level detection means signals the distribution means to begin filling the first cell with waste water.

Preferably, when the first cell is at a specified high level, the level detection means signals the distribution means to cease filling the first cell, and for the first cell to commence treatment of the waste water therein.

Preferably, once the first cell has ceased filling, and if the level detection means in a second cell is at a specified low level, then the level detection means in the second cell signals the distribution means to begin filling the second cell with waste water.

Preferably, the first cell does not refill with waste water until its level detection means has detected the specified low level again and no other treatment cell is filling.

Preferably, the level detection means detects the specified low level again after treatment of the waste water has finished and the treat effluent has H:\Shery1M\Keep\Speci\P62070.SPEC.doc 7/09/06 6 substantially exited the first cell.

Preferably, this sequence of filling, treating, Semptying and refilling continues sequentially through each treatment cell.

Preferably, the level detection means is a high water float.

00 Preferably, the level detection means also 00 00 signals the outlet of the primary batching tank to open and shut as required.

Preferably, the waste water treatment system also Scomprises a pump to assist in flowing the waste water from the primary batching tank to the at least one activated sludge tank.

Preferably, the pump is located between the primary batching tank and the distribution means.

Preferably, each treatment cell comprises an aerobic treatment chamber in which the waste water is aerated.

Preferably, each treatment cell comprises a filter chamber into which treated effluent is decanted.

Preferably, the filter chamber has a filter unit containing a filter, through which treated effluent flows to exit the filter chamber.

Preferably, the treated effluent flows upwardly through the filter unit.

Preferably, treated effluent is periodically back flowed through the filter to clean the filter.

Preferably, a three-way valve at the bottom of the filter unit switches between forward and back flow through the filter unit.

Preferably, the back flowed fluid is recycled to the aerobic treatment chamber of the treatment cell.

Preferably, additional pumps are used to produce the forward and back flows through the filter unit.

Preferably, each cell has its own additional pumps for operating the filter unit. Alternatively, all of the cells utilise the same set of pumps for operating H: \SheryIM\Keep\SpCCi \P62070.SPEC.dOC 7/09/06 7 the filter unit.

Preferably, the waste water treatment system also comprises a UV sterilisation system located after the at least one activated sludge tank.

In an embodiment, the system also comprises a further inlet connected to a conduit from at least one 00 fixture which produces fresh water based waste water, 00 00 wherein the at least one activated sludge tank is arranged to separately treat the fresh water based waste water and the salt water based waste water aerobically.

SIn this embodiment, the waste water treatment CI system may also comprise a second batching tank for holding the fresh water based waste water. The waste water treatment system may then also comprise at least two activated sludge tanks, at least one for separately treating the salt water based waste water and at least one for separately treating the fresh water based waste water.

Alternatively, an integrated system could be provided whereby the salt water based and the fresh water based waste waters are treated in the same at least one activated sludge tank, although not at the same time.

According to a second aspect of the present invention, there is provided a process for treating salt water based waste water, the process comprising the step of aerobically digesting the waste water in an activated sludge tank to produce a treated effluent.

Preferably, the process further includes the step of recycling the treated effluent to flush a toilet.

Preferably, the process is carried out using the system according to any of the embodiments and/or preferred options of the first aspect of the present invention.

According to a third aspect of the present invention, there is provided a waste water treatment system for treating waste water, the system comprising a first inlet connected to a conduit from at least one fixture which produces fresh water based waste water, a H: \Shery1M\Keep\Speci\P62070. SPEC. doc 7/09/06 8 second inlet connected to a conduit from at least one fixture which produces salt water based waste water, at Sleast one activated sludge tank for separately treating at least one of the fresh water based waste water and the salt water based waste water aerobically.

Preferably, the system also comprises at least 00 one outlet connected to a conduit to at least one of the 00 00 fixtures to recycle treated effluent from the activated sludge tank to the fixture.

Preferably, the system is the waste water system Son a vehicle.

C More preferably, on a boat, ship or other marine vessel.

Preferably, the fresh water based waste water is grey water.

Preferably, the salt water based waste water is black water.

Preferably, the at least one activated sludge tank is for separately treating the salt water based waste water, which is black water.

Preferably, the waste water treatment system further comprises a primary batching tank for holding the salt based waste water prior to treatment in the at least one activated sludge tank.

The waste water treatment system may also comprise a second batching tank for holding the fresh water based waste water. The waste water treatment system may then also comprise at least two activated sludge tanks, at least one for separately treating the salt water based waste water and at least one for separately treating the fresh water based waste water. Alternatively, an integrated system could be provided whereby the salt water based and the fresh water based waste waters are treated in the same at least one activated sludge tank, although not at the same time.

Alternatively, the fresh water based waste water may be disposed of or re-used without any treatment if it H:\Shery1M\Keep\Speci\P62070 .SPEC.doc 7/09/06 9 is grey water.

According to a fourth aspect of the present invention, there is provided a waste water treatment system for treating waste water, the system comprising a first inlet connected to a conduit from at least one fixture which produces fresh water based waste water, a 00 second inlet connected to a conduit from at least one 00 00 fixture which produces salt water based waste water, at least one activated sludge tank for treating the fresh water based waste water and the salt water based waste water aerobically, wherein, the fresh water based waste C1 water and the salt water based waste water are mixed in a ratio which does not cause the concentration of the salt in the mixed waste water to become too low or too high to kill the bacteria necessary for treating the waste water aerobically.

According to a fifth aspect of the present invention, there is provided a vehicle having a waste water treatment system according to any one of the embodiments and/or preferred options of the first, third, and fourth aspects of the present invention.

The vehicle may be any motorised or non-motorised transport apparatus such as a car, bus, truck, train caravan, trailer, carriage, barge, boat, ship or other land or marine vessel.

According to a sixth aspect of the present invention, there is provided a vehicle having a waste water treatment system for treating fresh water based waste water, the system comprising at least one activated sludge tank for treating the waste water aerobically, an inlet connected to a conduit from at least one fixture which produces fresh water based waste water, and an outlet connected to a conduit to at least one of the fixtures to recycle treated effluent from the activated sludge tank to the fixture.

Preferably, for vehicles where the supply of fresh water is limited, fresh water can be conserved by H:\Sherylm\Keep\Speci\P62070.SPEC.doc 7/09/06 10 treating and recycling the waste water to at least one of the fixtures which produces the waste water rather than by Susing an alternative water source such as salt water, which if mixed with fresh water may prevent the treatment of the waste water in an activated sludge tank. This is because when fresh water is mixed with salt water the 00 bacteria required for aerobic digestion in the activated 00 00 sludge tank are killed.

The vehicle may be any motorised or non-motorised transport apparatus such as a car, bus, truck, train caravan, trailer, carriage, barge, boat, ship or other C land or marine vessel.

Preferably, the vehicle is a boat, barge, ship or other marine vessel.

Brief Description of the Drawing A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawing in which: Figure 1 is a schematic view of a waste water treatment system according to a preferred embodiment of the present invention.

Detailed Description of Preferred Embodiments Referring to Figure 1, a waste water treatment system 10 according to preferred embodiments of the present invention comprises an activated sludge unit 11 for treating the waste water aerobically which receives waste water from one or more fixtures 12. The treated effluent from the activated sludge unit 11 is recycled to be re-used in one of the fixtures 12. The waste water which the system 10 treats may be salt water based waste water, fresh water based waste water or a combination of both. In the waste water treatment system 10, the fresh water and salt water based waste waters are treated separately. By treating the salt water and/or the fresh water separately (ie. by not substantially mixing the H: \SherylM\Keep\Speci\P62070.SPEC.doc 7/09/06 11 streams) an activated sludge tank can be used to treat either type of waste water. This is because the bacteria Srequired to breakdown nutrients in the waste water are not killed by the water containing either too much or not enough salt. Thus, the waste water treatment system of the present invention requires less space in which it 00 needs to be accommodated when compared to conventional 00 00 systems whilst also being of a lower health and environmental risk because there is no requirement to store large amounts of waste water nor is especially toxic Swaste water disposed of untreated.

C1 In this regard, the Applicant has made an important development, as the conventional belief is that it is not possible to conduct an activated sludge treatment process on salt water based sewage because the saline conditions kill all the bacteria necessary for aerobic break down of the nutrients. However, if the concentration of salt in the water is maintained at a high enough level, then the Applicant has surprisingly found that the bacteria which live in such conditions can be used in an activated sludge process to break down the nutrients. Thus, in the present invention, treatment of the fresh water and salt water waste waters by an activated sludge process is possible so long as the streams are not substantially mixed.

It is noted that some mixing between the fresh water based waste water and the salt water based waste water may occur so long as the concentration of the salt in the respective waste waters does not become too low or too high to kill the bacteria necessary for aerobic treatment of the waste water.

In the embodiment shown in Figure i, all of the fixtures 12 provide effluent of the same type (ie. fresh water or salt water), and thus their effluent is mixed prior to treatment in the activated sludge unit 11.

However, if some of the fixtures 12 produced salt water effluent and others produced fresh water effluent then a H:\SherylM\Keep\Speci\P62070.SPEC.doc 7/09/06 12 different arrangement to that shown in Figure 1 would be a used, whereby the effluent of different components was Sseparated.

The treatment system 10 also comprises a primary batching tank 13 in which waste water is held prior to being sent to the activated sludge unit 11 for treatment.

00 00If there are fixtures 12 which produce fresh water 00 effluent and fixtures which produce salt water effluent, then a second batching tank (not shown) may be employed so that both components may be collected prior to the treatment. In this scenario, the waste water treatment c system 10 may comprise distinct systems for treating the fresh water based waste water and the salt water based waste water with the activated sludge unit 11 for treating the fresh water and another activated sludge unit for treating the salt water. Alternatively, an integrated system could be provided to treat the salt and fresh water waste waters in the same activated sludge unit 11, although not at the same time.

The fixtures 12 from which the waste water treatment system 10 receives waste water may be any conceivable waste water producing fixture including those shown in Figure 1; a toilet 20, a bath 21, a shower 22, a basin 23 and a sink 24. Of these fixtures, the toilet produces black water. The other fixtures referred to above produce grey water.

Importantly, the grey water producing fixtures 12; the bath 21, the shower 22, the basin 23 and the sink 24 are usually fixtures which produce fresh water based waste water. However, the toilet 20 may produce either fresh water or salt water based waste water, and typically in situations where the supply of fresh water is limited, for example on boats, salt water is used to flush the toilet. If salt water is used to flush the toilet then the effluent from the toilet 20 is treated separately from the effluent from the remaining fixtures in the treatment system 10. The fresh water effluent from the H: \SherylM\Keep\Speci\P62070.SPEC.doc 7/09/06 13 remaining fixtures 12 may be sent to a second batching tank (not shown) for treatment in the treatment system Sas described above, or alternatively, as these fixtures produce grey water, their effluent may be disposed of or re-used without any treatment. Generally, in the case of boats, this grey water is disposed of overboard as there 00 is few applicable circumstances in which untreated grey 00 00 water can be used on a boat. Furthermore, it is generally not feasible to store grey water for any length of time as it fouls readily (and would then require the same level of Streatment as black water), and would also require substantial storage space, which is a significant problem on boats.

If fresh water is used to flush the toilet then its effluent may be collected together with the effluent from the other fixtures in the primary batching tank 13 prior to treatment in the activated sludge unit 11.

The waste water treatment system 10 also comprises a treated effluent holding tank 14 in which the effluent from the activated sludge unit 11 is held. The water in the treated effluent holding tank 14 is recycled to flush the toilet 20 from which the treatment system receives waste water. In order to conserve storage space, in some situations, such as on boats, the treated effluent holding tank 14 may be sized to have enough water to flush the toilet 20. Any excess treated effluent may be simply disposed. Because of the quality of the treated effluent, this disposal does not pose a significant risk either to human health or the environment.

The activated sludge unit 11 may comprise multiple treatment cells as shown in Figure 1, or may just comprise a single treatment cell. The advantage of using multiple cells in the treatment system 10 is that smaller cells (which occupy less space than one large cell) can be operated on a continuous batch process. This is because whilst one cell is filling with waste water, other cells H:\SherylM\Keep\Speci\P62070.SPEC.doc 7/09/06 14 can operate at various stages of the treatment process.

Referring specifically to Figure i, the activated Ssludge unit 11 according to this embodiment comprises a first treatment cell 16 and an essentially identical second treatment cell 17 (although not shown in detail in Figure The treatment cells 16, 17 are similar to the 00 Applicant's treatment plant described in AU 674511, but 00 00 with some additional features which will become apparent further on in the specification.

The cells 16,17, are connected to the outlet of the primary batching tank 13 via a three-way valve 18. The C outlet from the primary batching tank 13 is connected to the inlet of the three-way valve 18, whose outlets are connected to respective cells 16, 17. Thus flow to the cells 16, 17 can be distributed by opening and shutting the inlets of the three-way valve 18. It is to be appreciated that if the activated sludge unit 11 comprised additional cells, that extra three-way valves could be employed to distribute the flow from the primary batching tank 13 to the cells. Alternatively, some other kind of distribution means, whether mechanical or not, could equally be applied to distribute the flow to the cells.

Each cell 16, 17 has a high water float 30 to detect the level of waste water in the cell 16, 17 and thus control the filling of the cells 16, 17. At start-up of the waste water treatment system 10, both cells 16, 17 are empty and their high water floats 30 are residing at the bottom of the cell 16, 17. A signal from the high water float 30 in the first cell 16 is sent to a float switch 31 in the primary batching tank 13 to open its outlet to allow flow to the three-way valve 18 which is also controlled to open its outlet to the first cell 16.

The treatment system 10 may also comprise a pump 19 between the primary batching tank 13 and the three-way valve 18 to assist in the flow of waste water from the batching tank 13 to the cells 16, 17 of the activated sludge unit 11.

H:\Sherylm\Keep\Speci\P62070 .SPEC.doc 7/09/06 15 When the first cell 16 has filled, its high water float 30 reaches a maximum point in the cell 16 and Sconsequently signals the three-way valve 18 to close its outlet to the first cell 16. The high water float 30 in the second cell 17 then signals the three-way valve 18 to open its outlet to the second cell 17 so as to begin 00 00filling the second cell 17 in the same manner.

00 If both cells 16, 17 are full, then both outlets on the three-way valve 18 are closed, the outlet from the primary batching tank 13 is closed and the pump 19 is Sswitched off. Thus it is the cells 16,17 themselves which CI control their filling, operation and refilling.

Once the first cell 16 is filled, the treatment process of the waste water in this cell commences.

Importantly, refilling of the cells 16, 17 does not occur until the treatment process has completed, the treated effluent has been substantially discharged from the cell 16, 17 and the high water float 30 has fallen to a specified position towards the bottom of the cell. It is also noted that if the level of waste water in the primary hatching tank 13 is too low, then filling of the cells 16, 17 is suspended, the valve 18 and batching tank 13 are closed and the pump 19 switched off until the primary batching tank 13 has filled to a specified level.

Thus, it is highly desirable if design of the cells 16, 17 of the activated sludge unit 11 is such that whilst one cell is in the treatment phase, the other cell is in the filling phase (thus obtaining continuous batch operation). It is also desirable to design the primary batch tank 13 so that it is of sufficient size to provide a constant flow to the cells 16, 17 whilst also buffering the activated sludge unit 11 against peak flows into the treatment system 10 from the fixtures 12 (eg. the toilet being flushed or the bath 21 being emptied).

Commencement of the treatment process in the cells 16, 17 involves firstly aeration of the waste water in an aerobic treatment chamber of the cell 16, 17 whereby H:\SherylM\Keep\SpeCi\P62O7O.SPEC.doc 7/09/06 16 a controller operated compressor (not shown) which delivers air through a pipe 32. After the waste water has Sbeen sufficiently aerated, the solid sludge is allowed to settle to the bottom of the cell 16, 17 leaving a relatively clear treated effluent above the sludge for discharge from the cell 16,17. The aerobic treatment 00 00chamber thus requires periodic de-sludging. The treated 00 effluent is decanted from the aerobic treatment chamber into a filter chamber 33 from which the treated effluent is discharged.

The filter chamber 33 has an upflow filter unit C 34, that is, treated effluent flows in to the filter unit 34 through its bottom 35 and out the top 36 of the chamber, passing through a filter 37 therebetween. A treated effluent pump 38 helps draw effluent through the filter 37 and out of the filter chamber 33. This prevents any stirred up solids from the bottom of the cell 16, 17 exiting with the treated effluent. This is particularly important in the application of the waste water treatment system 10 of the present invention on boats, where rough seas are quite likely to cause some disturbance to the settled solids.

A recycle pump 39 periodically draws fluid in the reverse direction through the filter unit 34 and pumps it to the aerobic treatment chamber of the cell 16, 17. This is done so as to produce a back flow which cleans the filter 37 and reduces the frequency of replacing the filter 37. A three-way valve 40 at the bottom 35 of the filter unit 34 switches between upflow and backflow through the filter 37.

In one alternative embodiment, the ancillary equipment for the cells 16, 17, ie. the treated effluent pump 38 and the recycle pump 39, may be arranged, via a series of valves and switches, to be commonly used for both cells 16, 17. However, in another embodiment, the cells each have their own pumps 38,39.

The treated effluent exiting the cells 16, 17 of H:\SheylM\Keep\Speci\P62070.SPEC.doc 7/09/06 17 the activated sludge unit 11 passes through a UV sterilisation system 45, in which all remaining bacteria Sand pathogens are killed, prior to entering the treated effluent holding tank 14, from which, as described above, the treated effluent can be recycled for use in the flush of the toilet 00 In the claims which follow and in the preceding 00 00 description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as S"comprises" or "comprising" is used in an inclusive sense, ^C 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.

H: \SherylM\Keep\Speci\P62070. SPEC. doc 7/09/06

Claims (21)

1. A waste water treatment system for treating salt water based waste water, the system comprising at least one activated sludge tank for treating the waste water aerobically and an inlet connected to a conduit from 00 at least one fixture which produces salt water based waste 00 00 water.

2. A waste water treatment system as claimed in claim i, wherein the system also comprises an outlet C connected to a conduit to at least one of the fixtures to recycle treated effluent from the activated sludge tank to the fixture.

3. A waste water treatment system as claimed in either claims 1 or 2, wherein the system also comprises a control means for controlling treatment of the waste water in batches.

4. A waste water treatment system as claimed in any of the preceding claims, wherein the system also comprises a primary batch tank for holding the waste water prior to treatment in the at least one activated sludge tank.

A waste water treatment system as claimed in any of the preceding claims, wherein the at least one activated sludge tank comprises at least one treatment cell.

6. A waste water treatment system as claimed in claim 5, wherein the system also comprises a distribution means for distributing the flow of waste water to each treatment cell. H:\Shery1M\Keep\Speci\P62070.SPEC.doc 7/09/06 19

7. A waste water treatment system as claimed in either claims 5 or 6 when dependent on claim 3, wherein the control means comprises a waste water level detection means in each treatment cell for detecting the level of waste water in each treatment cell to control the filling, treating, emptying and refilling of each cell. 00 00 00

8. A waste water treatment system as claimed in any one of claims 5 to 7, wherein each treatment cell comprises an aerobic treatment chamber in which the waste Swater is aerated.

9. A waste water treatment system as claimed in any one of claims 5 to 8, wherein each treatment cell comprises a filter chamber into which treated effluent is decanted.

A waste water treatment system as claimed in claim 9, wherein the filter chamber has a filter unit containing a filter, through which treated effluent flows to exit the filter chamber, and wherein treated effluent is periodically backflowed through the filter to clean the filter.

11. A waste water treatment system as claimed in any one of the preceding claims, the system also comprising a UV sterilization system located after the at least one activated sludge tank.

12. A waste water treatment system as claimed in any of the preceding claims, wherein the system also comprises a further inlet connected to a conduit from at least one fixture which produces fresh water based waste water, wherein the at least one activated sludge tank is arranged to separately treat the fresh water based waste water and the salt water based waste water aerobically. H:\SherylM\Keep\Speci\P62070.SPEC.doc 7/09/06 20

13. A waste water treatment system as claimed in claim 12, the system comprising at least two activated Ssludge tanks, at least one activated sludge tank for separately treating the salt water based waste water and at least one activated sludge tank for separately treating the fresh water based waste water. 00 00 00

14. A waste water treatment system as claimed in claim 12, wherein the at least one activated sludge N 10 tank is arranged to treat both the salt water based waste water and the fresh water based waste water, although not C at the same time.

A waste water treatment system for treating waste water, the system comprising a first inlet connected to a conduit from at least one fixture which produces fresh water based waste water, a second inlet connected to a conduit from at least one fixture which produces salt water based waste water, at least one activated sludge tank for separately treating at least one of the fresh water based waste water and the salt water based waste water aerobically.

16. A waste water treatment system for treating waste water, the system comprising a first inlet connected to a conduit from at least one fixture which produces fresh water based waste water, a second inlet connected to a conduit from at least one fixture which produces salt water based waste water, at least one activated sludge tank for treating the fresh water based waste water and the salt water based waste water aerobically, wherein, the fresh water based waste water and the salt water based waste water are mixed in a ratio which does not cause the concentration of the cell in the mixed waste water to become too low or too high to kill the bacteria necessary for treating the waste water aerobically. H:\SheryM\Keep\Speci\P6270 .SPEC.doc 7/09/06 21

17. A vehicle having a waste water treatment system as claimed in any one of the preceding claims.

18. A vehicle having a waste water treatment system for treating fresh water based waste water, the system comprising at least one activated sludge tank for 00 treating the waste water aerobically, an inlet connected 00 00 to a conduit from at least one fixture which produces fresh water based waste water, and an outlet connected to a conduit to at least one of the fixtures to recycle Streated effluent from the activated sludge tank to the CI fixture.

19. A vehicle as claimed in either claim 17 or 18, wherein the vehicle is a boat, barge, ship or other marine vessel.

A process for treating salt water based waste water, the process comprising the step of aerobically digesting the waste water in an activated sludge tank to produce the treated effluent.

21. A waste water treatment system as substantially described herein, with reference to the accompanying drawing. H:\Sherylm\Keep\SpeCi\P62070.SPEC.doc 7/09/06