AU771729B2

AU771729B2 - Gas treatment system

Info

Publication number: AU771729B2
Application number: AU10089/02A
Authority: AU
Inventors: Ivan Patrick De Souza
Original assignee: Water Corp
Current assignee: Plastic Fabricators (wa) Pty Ltd
Priority date: 2001-01-09
Filing date: 2002-01-09
Publication date: 2004-04-01
Anticipated expiration: 2022-01-09
Also published as: AU1008902A

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT (Original) APPLICATION NO:

LODGED:

COMPLETE SPECIFICATION LODGED:

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PUBLISHED:

RELATED ART: NAME OF APPLICANT: ACTUAL INVENTOR: ADDRESS FOR SERVICE: WATER CORPORATION C 1 SEC S 104 IVAN PATRICK DE SOUZA x LORD COMPANY, Patent Trade Mark Attorneys, of 4 Douro Place, West Perth, Western Australia, 6005, AUSTRALIA.

GAS TREATMENT SYSTEM INVENTION TITLE: DETAILS OF ASSOCIATED PROVISIONAL APPLICATION NO'S: Australian Provisional Patent Application Number PR2443 filed on January 9, 2001 The following Statement is a full description of this invention including the best method of performing it known to us

TITLE

"GAS TREATMENT SYSTEM" The present invention relates to a gas treatment system.

It is known to require treatment systems to remove noxious air emissions from sewerage collection systems and other foul odour producing operations. Sewer gases, as well as containing odours, may contain volatile organic compounds and other toxic air pollutants including hydrogen sulphide and methane. The use of vacuum sewage S 10 collection and transfer stations can result in sufficient quantities of sewer gases being °eoee emitted from transfer stations and this emission may have a significant environmental impact.

A known type of treatment system used for the treatment of malodorous gases is a bulk media biofilter bed. A biofilter bed typically consists of a pit at ground level eeooo o 15 which is filled with a compost mix. The compost mix is kept moist by the use of water sprinklers or trickle hoses. Malodorous gas is piped to the base of this pit, and S passes through the compost mix to reach the surface. As gas passes through the compost mix, micro-organisms within the compost mix assist to oxidise the malodorous gas and convert the contaminants into harmless, odourless end products.

There are several problems encountered with known biofilters. The micro-organisms in the filters require certain ambient temperatures and humidity in order to function effectively. When atmospheric conditions are outside of these requirements the biofilters can fail to effectively remove odours from the gas. If the conditions remain unfavourable, permanent damage may be done to the micro-organisms in the filters.

A further problem encountered is in compacting of the compost mix. Such compacting, which can be caused by rain, reduces the capacity of the compost mix to remove odours from the gas.

The present invention attempts to overcome at least in part some of the aforementioned disadvantages of previous gas treatment systems.

In accordance with a first aspect of the present invention there is provided a gas treatment system comprising a plurality of treatment elements arranged to reduce odours from a gas passing therethrough, adjacent treatment elements being separated by an air gap, the treatment elements being arranged so that, in use, gas being treated 10 must pass through more than one treatment element.

S•In accordance with a second aspect of the present invention there is provided a method of treating malodorous gas, the method comprising passing the gas through a plurality of treatment elements, each treatment element being arranged to reduce odours on the gas passing therethrough, adjacent treatment elements being separated oooo, by an air gap.

**The present invention will now be described, by way of example, with reference to S.the accompanying drawing which is a cut away view of a gas treatment system in accordance with the present invention.

Referring to the Figure, there is shown a gas treatment system 10. The gas treatment system 10 comprises a moisture control unit 22 and a parallel series of treatment units 24, 26, 28 and 30. Each of the moisture control unit 22 and treatment units 24, 26, 28, is comprised of trays having an outer housing 12. Each outer housing 12 may be constructed from polyethylene or other suitable material.

The moisture control unit 22 includes a water tray 70, a moisture separating tray 72 and a water collection tray 74. The water tray 70 is disposed above the moisture separating tray 72, and includes a water bath 76, an air space 78 disposed above the water bath 76 and a perforated sheet 80 separating the water bath 76 and the air space 78. The water tray 70 includes gas inlets 56 which open into the water bath 76. A carrying pipe 34 opens into the air space 78 and extends upwardly and away from the moisture control unit 22.

The level of the water bath 76 may be maintained at a desired level by a ball float valve. The temperature of the water bath 76 may be maintained by a heating device such as an electric emersion heater.

The water collection tray 74 is arranged beneath the moisture separating tray 72 and is arranged to collect water separated from the gas in the moisture separating tray 72.

.i An inlet pipe 32 extends along the top of gas treatment system 10. The carrying pipe 34 opens into the inlet pipe 32. The inlet pipe 32 has outlets 36, 38, 40 and 42 spaced ee s15 along the length of the inlet pipe 32, such that the outlets 36, 38, 40 and 42 open into "77.

the top of treatment units 24, 26, 28 and 30 respectively.

Each treatment unit 24, 26, 28 and 30 comprises a plurality of trays, each tray including a treatment element 52. Each treatment element 52 comprises a substantially rectangular bed of biofiltration material, for instance compost mix. Each treatment element 52 is arranged so that any gas introduced above a treatment element 52 must pass through that treatment element 52 if there is a pressure differential between the regions above and below that treatment element 52.

Provision may be made for removal of part of the housing 12 of a tray in order for a treatment element 52 to be changed.

The height of the treatment elements 52 is chosen so that, in use, the flow rate of gas through each treatment element 52 allows micro-organisms in that treatment element 52 to oxidise volatile organic compounds contained in the gas. The height of the treatment elements 52 is further chosen to be sufficiently small enough to prevent compaction of the biofiltration material. Adjacent treatment elements 52 are separated by an air gap 54. The air gap 54 will generally contain a mixture of air and malodorous gas, however may contain entirely malodorous gas.

The treatment elements 52 may be disposed on trays having an air pervious base. The -trays may include a sealing means about their periphery. The trays may be supported by guide plates arranged about the base of the treatment elements 52.

i An outlet pipe 82 extends along the base of gas treatment system 10. The outlet pipe 82 has inlets 84, 86, 88 and 90 spaced along the length of the outlet pipe 82, such that the inlets 84, 86, 88 and 90 open into the base of treatment units 24, 26, 28 and respectively.

The outlet pipe 82 has an outlet 92 which opens into the moisture separating tray 72 of the moisture control unit 22.

The moisture separating tray 72 may include stainless steel swarf or coils onto which moisture can condense.

An exhaust pipe 60 is arranged externally of the moisture control unit 22. The exhaust pipe 60 has a first end 62 which opens into the moisture separating tray 72 of the moisture control unit. The exhaust pipe 60 has a second end which is located in a position above the top of the gas treatment apparatus 10. The second end includes vents which are open to the atmosphere.

Each treatment unit 24, 26, 28, 30 is sealed such that gas can only enter the treatment unit 24, 26, 28, 30 through outlet 36, 38, 40, 42 respectively, and gas can only exit the treatment unit 24, 26, 28, 30 through inlet 84, 86, 88, 90 respectively.

The gas treatment system 10 is thus a closed unit except for the gas inlet 56 and exhaust pipe In use, malodorous gas is introduced into the gas treatment apparatus 10 through the gas inlet 56. The gas bubbles through the water bath 76 and passes through the perforated sheet 80 into the air space 78, thus becoming saturated with moisture. The gas enters the inlet pipe 32 via the carrying pipe 34, and flows through the pipe to the treatment units 24, 26, 28 and 30. The gas then passes through the treatment elements 52 in one of the treatment units 24, 26, 28, 30, being treated and de-odorised in the process. The gas exits the treatment units 24, 26, 28, 30 via the outlet pipe 82, through which it flows into the moisture separating tray 72. Moisture is extracted in the moisture separating tray, and collected in the water collection tray 74. The relatively dry, de-odorised gas is then exhausted to the atmosphere through the second end of the exhaust pipe Various control mechanisms may be introduced into the gas treatment system Water sprays may be included in the treatment units 24, 26, 28, The compost mix used in the treatment elements may be as follows: 75% 80% Mulched tree plant trimmings 8% Peat 7% 10% Stabilised Biosolids 1% 5% Sawdust 3 kg Lime powder/cubic meter of filter media Each treatment element may comprise approximately 0.25 m 3 of compost mix.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention. For instance, the number and orientation of treatment units and treatment elements may be varied to suit particular situations.

It will be appreciated that the invention has been described and shown in the drawings in a modular arrangement. The gas treatment apparatus may alternatively be housed in a building.

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Claims

1. A gas treatment system comprising a vertical array of treatment elements arranged to reduce odours from a gas passing therethrough, adjacent treatment elements being separated by an air gap, the treatment elements being arranged so that, in use, gas being treated must pass through more than one treatment element.

2. A gas treatment system as claimed in Claim 1 wherein each treatment element is independently replaceable.

3. A gas treatment system as claimed in any one of the preceding claims wherein the treatment elements are substantially rectangular.

4. A gas treatment system as claimed in any one of the preceding claims,wherein the treatment element comprises biofiltration material A gas treatment system as claimed in Claim 4, wherein the biofiltration oe material is compost.

6. A gas treatment system as claimed in Claim 5, wherein the compost comprises 80% mulched tree plant trimmings; 5% 8% Peat; 7% to Stabilised Biosolids; and 1% 5% Sawdust.

7. A gas treatment system as claimed in any one of the preceding Claims, wherein there is provided a water bath through which gas is bubbled.

8. A gas treatment system as claimed in Claim 7, wherein there is provided a perforated sheet positioned above the water bath through which bubbles of gas must pass.

9. A gas treatment system as claimed in Claim 7 or Claim 8, wherein there is provided a heating device within the water bath. A gas treatment system as claimed in any one of Claims 7 to 9, wherein there is an air space above the water bath, the air space being in fluid communication with at least one treatment element.

11. A gas treatment system as claimed in any one of the preceding Claims, wherein the treatment elements are arranged in plurality of treatment units, the treatment units being arranged parallel to each other such that gas is arranged to pass through any one treatment unit.

12. A gas treatment system as claimed in Claim 11 wherein any one treatment unit can be isolated from the others.

13. A gas treatment system as claimed in Claim 11 or Claim 12, wherein the system includes water sprays within the treatment units.

14. A gas treatment system as claimed in any one of the preceding Claims, wherein the system includes a moisture separating region.

15. A gas treatment system as claimed in any one of the preceding claims, wherein each treatment element is arranged on an air pervious base.

16. A gas treatment system as claimed in any one of the preceding Claims, wherein each treatment element is contained within a tray.

17. A gas treatment system as claimed in Claim 16, wherein there is provided a sealing means about the periphery of each tray such that gas can not pass through joins between adjacent trays. 18 A method of treating malodorous gas, the method comprising passing the gas through a vertical array of treatment elements, each treatment element being arranged to reduce odours in the gas passing therethrough, adjacent treatment elements being separated by an air gap.

19. A method of treating malodorous gas as claimed in Claim 18, the method including the step of introducing moisture into the gas prior to passing the gas through the treatment elements. A method of treating malodorous gas as claimed in Claim 19, the method including the step of removing moisture from the gas after it has passed through the treatment elements.

21. A gas treatment system as herein before described with reference to, and as shown in, the accompanying drawings. DATED THIS 5 T H DAY OF FEBRUARY 2003. WATER CORPORATION By their Patent Attorneys LORD COMPANY PERTH, WESTERN AUSTRALIA *go o• ogoo