AU2007221838A1

AU2007221838A1 - A wastewater treatment system

Info

Publication number: AU2007221838A1
Application number: AU2007221838A
Authority: AU
Inventors: Brian Victor Hawthorne; Peter John Hawthorne
Original assignee: Bv Hawthorne Pty Ltd
Current assignee: Bv Hawthorne Pty Ltd
Priority date: 2006-10-05
Filing date: 2007-10-05
Publication date: 2008-04-24

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "A WASTEWATER TREATMENT SYSTEM" The following statement is a full description of this invention, including the best method of performing it known to me/us: O1 (N

TITLE

c, o "A WASTEWATER TREATMENT SYSTEM" 0 FIELD OF THE INVENTION This invention relates to a wastewater treatment system. In 00oo rn 5 particular, the invention relates to a wastewater treatment system for 00 1 household sewage and therefore will be described in this context. However, it should be appreciated that the wastewater treatment system may be used for other purposes.

BACKGROUND OF THE INVENTION Wastewater treatment systems for treating household sewage are well known. Some of these wastewater systems use a primary tank to separate large solids from the waste water and then pass the wastewater to an aerobic sand filtration bed to purify the wastewater. This aerobic sand filtration bed allows wastewater, i.e. liquid with suspended solids, to be treated by allowing the liquid with suspended solids to make intimate contact with and be oxidised by aerobic bacteria present in the filtration bed. The liquid with suspended solids is then distributed into a designated area of ground.

The filtration bed includes a lower volume of sand covered by aggregate. Geotextile is located over the aggregate and turf is placed over the filtration bed. A series of distribution pipes distribute the liquid with suspended solids on the top of the sand. The sand maintains the aerobic bacteria that are used to mineralise the liquid with suspended solids. That is, the aerobic bacteria is used in a bio-chemical process whereby organic

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O material is converted to inorganic material using a microbiological process.

O Current practice allows the wastewater to enter the aerobic 0 sand filter in a somewhat untreated condition if the primary tank offers little separation of large solids. As a result of this practice an extremely large 00oo Mc 5 volume of sand and consequently a large surface area is required to effect o00 N the treatment process. This limits the use of wastewater treatment systems

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of this nature to locations that have a sufficient available area for a filtration bed of an adequate size. Hence, wastewater treatment systems of this nature are generally unable to be used in built up residential locations or residences on small parcels of land.

OBJECT OF THE INVENTION It is an object of the invention to overcome or alleviate one or more of the above disadvantages or provide the consumer with a useful or commercial choice.

SUMMARY OF THE INVENTION In one form, although not necessarily the only or broadest form, the invention resides in a wastewater treatment system comprising: a primary unit for separating large solids from a liquid having suspended solids; a filtration unit fluidly connected to the primary unit, the filtration unit including a filter media to maintain an aerobic bacteria culture and a distribution mechanism located above the filter media for distributing the liquid with suspended solids onto the filter media; and a disinfection unit fluidly connected to the filtration unit, the

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disinfection unit able to be used to add disinfectant to the liquid with suspended solids.

In another form, the invention resides in a filtration unit for a wastewater treatment system, the filtration unit comprising: a filter media to maintain an aerobic bacteria culture; and a distribution mechanism located above the filter media for distributing a liquid with suspended solids onto the filter media; wherein the filter media is directly open to air.

In yet another form, the invention resides in a distribution mechanism for distributing liquid over a filter media, the distribution mechanism comprising: a series of pipes; and a tilt assembly located above the series of pipes, the tilt assembly includes a reservoir having a weir located on one side of the reservoir and flow restrictors located on the opposite side of the reservoir, wherein the tilt assembly is movable between a resting position in which liquid is held in the reservoir and a distributing position in which liquid is poured from the reservoir into the pipes.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described with reference to the accompanying drawings in which: FIG. 1 is a schematic view of a wastewater treatment system according to an embodiment of the invention; FIG. 2 is a side view of a primary unit outlet baffle; 4 SFIG. 3 is a side sectional view of a primary unit outlet baffle; o FIG. 4 is a top view of a distribution mechanism; f FIG. 5 is a side view of a distribution mechanism; and FIG. 6 is a top sectional view of a disinfection unit.

00oo M0 5 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS oo SFIG. 1 shows a schematic representation of a waste water treatment system 10. The waste water treatment system 10 includes a primary unit 20, a filtration unit 30 and a disinfection unit 50. The primary unit 20, filtration unit 30 and disinfection unit 50 are all located substantially below ground with respective inspection openings 21, 31,51 for each of the primary unit 20, filtration unit 30 and disinfection unit The primary unit 20 contains raw sewage that flows from a domestic household. The primary unit 20 includes a primary tank 22 that is made of concrete. However, it should be appreciated that the tank 22 may also be made of other materials such as plastic. The primary unit 20 also includes a primary unit inlet 23 that allows sewage to flow into the primary tank. A primary unit inlet baffle 24 is connected to the primary tank inlet 23.

The primary unit inlet baffle 24 assists in preventing turbulence within the primary tank 22 so that with the ingress of sewage, waves at the top of the primary tank 22 are reduced. A primary unit wall baffle 25 extends from a base of the primary tank 22 to adjacent the top of the primary tank 22. A primary unit wall baffle aperture 26 extends through the primary unit wall baffle to allow liquid with suspended solids to pass from one side of the primary unit wall baffle 25 to the other side of the primary unit wall baffle bs A primary unit outlet baffle 27 is used to pass liquid with

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o suspended solids from the primary tank 22 out of a primary unit outlet 28 Slocated within the primary tank 22. The primary unit outlet baffle 27, shown in more detail in FIGS. 2 and 3, includes an elongate body 271 having a 00 base cap 272 located at a lower end of the elongate body 271 and a gauze 00 cap 273 located at an upper end of the elongate body. Inlet grooves 274 are located adjacent a lower end of the elongate body 271 to allow liquid with suspended solids to pass into the primary unit outlet baffle 27. Gas deflection flanges 275 are located adjacent the inlet grooves 274 to assist in preventing suspended solids from entering into the primary unit outlet baffle 271 and out the primary unit outlet 28. A scoria bag 276 with associated handle 277 and containing scoria is located within the elongate body 271 on stop 278 to provide an additional filter for any suspended solids that may have passed into the elongate body 271.

The filtration unit 30 includes a filtration tank 32, a filtration unit inlet pipe 33, a distribution mechanism 34, filter media 35, a collection pipe 36, an overflow pipe 37 and a filtration unit outlet 38.

The filtration tank 32 is made of concrete though other materials may also be used. The filter media 35 is located within the bottom of the filtration tank 32. The filter media 35 is open directly with the air. The filter media 32 in this embodiment is sand however it is envisaged that other materials such as foam or aggregate may be used. The sand covers the collection pipe 36 that is connected to the filtration unit outlet 38. The collection pipe 36 collects liquid with suspended solids that passes through ~u

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O the sand. A geotextile 39 covers the collection pipe 36 to prevent sand from c blocking holes (not shown) located within the collection pipe 36. Aggregate 40 is located adjacent an end of the collection pipe 36 to allow for the ingress of liquid with suspended solids into the end of the collection pipe. The 00oO overflow pipe 37 is connected to the end of the collection pipe 36 and o00 c extends upwardly through the top of the sand.

The filtration unit inlet 33 is fluidly connected to the primary outlet 28. A scoria bag 42 is located within the filtration unit inlet 33. The scoria bag 42 provides media on which aerobic bacteria is able to grow effectively. Liquid with suspended solids that passes through the filtration unit inlet 33 and hence through the scoria bag 42 is able to pick up the bacteria. After the liquid with suspended solids passes through the filtration unit inlet 33, it falls into the distribution mechanism 34. The mechanism distributes liquid with suspended solids that flows from the filtration unit inlet 33 relatively evenly over the sand.

The distribution mechanism 34 is shown more clearly in FIGS.

4 and 5 and includes a tilt assembly 341, a central feeder pipe 342, four linking pipes 343 and eight outer pipes 344. The central leader pipe 342 is upstanding and is located below the tilt assembly 341. The feeder pipes extend outwardly from a base of the central feeder pipe 342 and lead into the outer pipes 344. The outer pipes 344 are connected to each other to form a ring. A series of holes 345 are located in the top of each of the outer pipes 344.

The tilt assembly 344 includes a reservoir 346 that is pivotally N mounted above the central pipe. A weir 347 is located on one side of the o reservoir 346 with flow restrictors 348 located on the opposite side of the reservoir 346.

In use, liquid with suspended solids flows through the filtration 00 oo unit inlet 33 and flows into the reservoir 346 which is in a resting position.

00oO N This causes liquid with suspended solids to fill within the reservoir 346 until it reaches a top of the weir 347 in the reservoir 346 at which point liquid with suspended solid flows over the weir 347 into the remainder of the reservoir 344. When sufficient liquid with suspended solids has passed over the weir 347, this causes the reservoir 346 to tilt to a distribution position and cause liquid with suspended solids to flow from the reservoir 346 into the central feeder pipe 342. The flow restrictors 348 restrict the flow of liquid with suspended solids from the reservoir 346 into the central feeder pipe 342 so that the reservoir 346 remains in a distribution position until the majority of liquid with suspended solids flows out of the reservoir 346. Therefore, if a large amount of liquid with suspended solids is flowing through the inlet into the reservoir 346, the reservoir 346 will remain in the distribution position.

After the liquid with suspended solids has passed from the reservoir into the central feeder pipe 342, the remaining liquid with suspended solids trapped at the end of the reservoir 346 by the weir 347 causes the tilt assembly to move back to the resting position.

After the liquid with suspended solids has passed into the central reservoir 342, liquid with suspended solids flows out evenly through the holes 345 located in the outer pipe 344. As the holes 345 are located in 0 O the top of the outer pipes 344, the feeder pipes 343 and outer pipes 344 will O always remain full with liquid with suspended solids. This enables an even distribution of liquid with suspended solids to flow from all of the holes 345 located in the outer pipes 344 onto the sand.

00oo This disinfection unit 50 shown in more detail in FIG. 6 includes 00oO C a disinfection tank 52, a disinfection unit inlet 53, a scum board 54, a first disinfection chamber 55, a second disinfection chamber 56 and a third disinfection chamber 57.

The disinfection tank 52 is made of concrete though it is envisage that the tank 52 may be made from different materials. The disinfection tank 52 is divided into a first disinfection chamber 55, a second disinfection chamber 56 and a third disinfection chamber 57.

The first distinction chamber 55 includes a chlorine tablet dispenser 58 that is connected to the disinfection unit inlet 53 so that chlorine tables can be passed into the first disinfection chamber 55. The disinfection unit inlet 53 is fluidly connected to the filtration unit outlet 38. The scum board 54 is located within the first disinfection chamber and assists in preventing any suspended solids that are collected at the top of the first disinfection chamber 55 from passing through the first disinfection chamber 55. The first disinfection chamber 55 allows a period of time for chlorine from the chlorine table to disinfect the liquid with suspended solids that has passed from the filtration unit A first disinfection unit partition 59 separates the first disinfection chamber 55 from the second disinfection chamber 56 and the (first disinfection chamber 55 from the third disinfection chamber 57. A first

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o chamber inlet baffle 60 is connected to a second chamber outlet baffle 61 to allow liquid with suspended solids to pass from the first disinfection chamber to the second disinfection chamber 56.

00 M 5 A series of agricultural pipes, 62 that have holes located 00 through the agricultural pipes, are located within the second disinfection 0 chamber 56. The agricultural pipes 62 provide a tortuous pathway through which the liquid with suspended solids must pass in order to enter third disinfection chamber 57. This assists in preventing suspended solids from entering the third disinfection chamber 57. A second disinfection unit partition 63 separates the second disinfection chamber 56 from the third disinfection chamber 57. A second chamber inlet baffle 64 is connected to a third chamber outlet baffle 65 to allow liquid with suspended solids to pass from the second disinfection chamber 56 to the third disinfection chamber 57.

The third disinfection chamber 56 includes a submersible pump 66. The submersible pump 66 pumps liquid with suspended solids from the disinfection chamber 56 to a designated area of ground when the liquid with suspended solids reaches a certain level within the third disinfection chamber 56.

In use, sewage is feed into the primary tank 22. Here large solids sink to the bottom of the primary tank 32 while scum floats to the top of the primary tank 32. The primary unit baffle wall 25 assists in prevent large solids and scum from passing from one side of the primary unit wall

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baffle 25 to the other side of the primary unit wall baffle as the aperture 26 to o allow liquid with suspended solids to pass is located adjacent the middle of

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the primary unit wall baffle 25. Once the liquid with suspended solids has passed through the primary unit wall baffle 25 it passes through the primary 00 unit outlet baffle 27. Again, the primary unit outlet baffle 27 is designed to 00 N assist in prevent suspended solids from passing through the primary unit Soutlet baffle 27.

N Once liquid with suspended solids passes through the primary unit outlet baffle 28, it passes through the primary unit outlet 28 and into the filtration unit inlet 33. The liquid with suspended solids is the passed into the distribution mechanism 34 where it is distributed relatively evenly over the sand. The sand contains an aerobic bacteria which assists in breaking down the liquid with suspended solids. The liquid with a less quantity of suspended solids passes through the collection pipe 36 and out the filtration unit outlet pipe 38. Any excess liquid with suspended solids that passes into the collection pipe 36 is able to pass through the overflow pipe 37 and back onto the top of the sand.

The liquid with suspended solids then passes into the first disinfection chamber 55 that where chlorine is added via the chorine tablet dispenser 58. This further breaks down the liquid with suspended solids.

The liquid with suspended solids then passes into the second disinfection chamber 56 where the liquid with suspended solids must pass through a tortuous pathway made of agricultural pipes 62. Again this reduces the amount of suspended solids with the liquid. The liquid with suspended solids ii then passes into the third disinfection chamber 56 where it is pumped from

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o the third disinfection chamber 57 to a designated area of land.

The filtration unit is able to reduce the land that the wastewater management system needs to operate effectively. The filtration unit is able 00 00 5 to maintain sufficient aerobic bacteria to treat wastewater due to its Sconstruction. This is due largely to the liquid with suspended solids being distributed evenly over the filter media and also the quantity of the suspended solids having been greatly reduced by the pre-treatment carried out in the prior stages.

Further, the wastewater system is passive. That is, the liquid with suspended solids are able to travel from the primary unit through the filtration unit and into the disinfection unit under the force of gravity. No pumps are required in order to transport the liquids with suspended solids from one unit to the next unit. Therefore, the wastewater system is able to be utilised in areas that have limited power supply such as in many third world countries.

The distribution mechanism allows intermittent dosing of the sand which allows the sand to dry between dosing, which maintains the survival of aerobic bacteria in the sand filtration bed.

It should be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit or scope of the invention.

Claims

2. The wastewater treatment system as claimed in claim1 wherein the primary unit includes a primary tank having an inlet baffle and an outlet baffle.
3. The wastewater treatment system as claimed in claim 2 wherein a wall baffle is located within the primary tank.
4. The wastewater treatment system of claim 2 wherein the outlet baffle includes an elongate body having a series of inlet grooves located at one end of the elongate body.
5. The wastewater treatment system of claim 4 wherein the gas deflection flanges are located adjacent the inlet grooves.
6. The wastewater treatment system of claim 4 or claim 5 wherein a scoria bag is located within the elongate body.
7. The wastewater treatment system of any one of the preceding claims wherein the filtration unit includes a filtration tank having an inlet pipe, a I0 N collection pipe and an outlet. o 8. The wastewater treatment system of any one of the preceding claims in which the filter media is directly open to air.
9. The wastewater treatment system of any one of the preceding claims oO 00 Mc 5 wherein the distribution mechanism includes: o00 N a series of pipes; and a tilt assembly located above the series of pipes, the tilt N assembly includes a reservoir having a weir located on one side of the reservoir and flow restrictors located on the opposite side of the reservoir, wherein the tilt assembly is movable between a resting position in which liquid is held in the reservoir and a distributing position in which liquid is poured from the reservoir into the pipes. The wastewater treatment system of claim 9 wherein the series of pipes includes a central feeder pipe connected to at least one feeder pipe, the at least one feeder pipe connected to at least one outer pipe, the at least one outer pipe have a plurality of holes located within the outer pipe.
11. The wastewater treatment system of claim 10 wherein the outer pipes form a ring.
12. The wastewater treatment system of claim 10 or claim 11 wherein the plurality of holes are located in the top of the outer pipes.
13. The wastewater treatment system of any one of the preceding claims wherein the disinfection unit includes a disinfection tank having a first disinfection chamber connected to a second disinfection chamber and a third disinfection chamber connected to the second disinfection chamber.
14. The wastewater treatment system of claim 13 wherein the first o disinfection chamber includes a chlorine dispenser.
15. The wastewater treatment system of claim 13 or 14 wherein the second disinfection chamber includes a tortuous pathway provide by a pipe 00 or pipes. 00 S16. The wastewater treatment system of claim 13, 14 or 15 wherein the third disinfection chamber includes a pump to pump liquid with suspended solids from the disinfection tank..
17. A filtration unit for a wastewater treatment system, the filtration unit comprising: a filter media to maintain an aerobic bacteria culture; and a distribution mechanism located above the filter media for distributing a liquid with suspended solids onto the filter media; wherein the filter media is directly open to air.
18. The filtration unit of claim 17 wherein the filtration unit includes a filtration tank having an inlet pipe, a collection pipe and an outlet.
19. The filtration unit of claim 17 or claim 18 wherein the distribution mechanism includes: a series of pipes; and a tilt assembly located above the series of pipes, the tilt assembly includes a reservoir having a weir located on one side of the reservoir and flow restrictors located on the opposite side of the reservoir, wherein the tilt assembly is movable between a resting position in which liquid is held in the reservoir and a distributing position in which liquid is poured from the reservoir into the pipes. The filtration unit of claim 19 wherein the series of pipes includes a Vt central feeder pipe connected to at least one feeder pipe, the at least one feeder pipe connected to at least one outer pipe, the at least one outer pipe 00 O have a plurality of holes located within the outer pipe. 00 S21. The filtration unit of claim 20 wherein the outer pipes form a ring.
22. The filtration unit of claim 20 or claim 21 wherein the plurality of holes are located in the top of the outer pipes.
23. A distribution mechanism for distributing liquid over a filter media, the distribution mechanism comprising: a series of pipes; and a tilt assembly located above the series of pipes, the tilt assembly includes a reservoir having a weir located on one side of the reservoir and flow restrictors located on the opposite side of the reservoir, wherein the tilt assembly is movable between a resting position in which liquid is held in the reservoir and a distributing position in which liquid is poured from the reservoir into the pipes.
24. The distribution mechanism of claim 23 wherein the series of pipes includes a central feeder pipe connected to at least one feeder pipe, the at least one feeder pipe connected to at least one outer pipe, the at least one outer pipe have a plurality of holes located within the outer pipe. The distribution mechanism of claim 24 wherein the outer pipes form a ring.
26. The distribution mechanism of claim 24 or claim 25 wherein the 16 plurality of holes are located in the top of the outer pipes. S27. A wastewater distribution system as herein before described with reference to the accompanying figures.
28. A filtration unit as herein before described with reference to the 00oo accompanying figures. 00oo c 29. A distribution mechanism as herein before described with reference to the accompanying figures.