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GB1595068A - Treatment of sewage in a sewer - Google Patents

Treatment of sewage in a sewer Download PDF

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Publication number
GB1595068A
GB1595068A GB10540/77A GB1054077A GB1595068A GB 1595068 A GB1595068 A GB 1595068A GB 10540/77 A GB10540/77 A GB 10540/77A GB 1054077 A GB1054077 A GB 1054077A GB 1595068 A GB1595068 A GB 1595068A
Authority
GB
United Kingdom
Prior art keywords
sewage
gas
oxygen
valve
sewer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB10540/77A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BOC Group Ltd
Original Assignee
BOC International Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BOC International Ltd filed Critical BOC International Ltd
Priority to GB10540/77A priority Critical patent/GB1595068A/en
Priority to AU34078/78A priority patent/AU520567B2/en
Publication of GB1595068A publication Critical patent/GB1595068A/en
Expired legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/02Aerobic processes
    • C02F3/12Activated sludge processes
    • C02F3/26Activated sludge processes using pure oxygen or oxygen-rich gas
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/02Aerobic processes
    • C02F3/12Activated sludge processes
    • C02F3/20Activated sludge processes using diffusers
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2307/00Location of water treatment or water treatment device
    • C02F2307/08Treatment of wastewater in the sewer, e.g. to reduce grease, odour
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00Technologies for wastewater treatment
    • Y02W10/10Biological treatment of water, waste water, or sewage

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  • Life Sciences & Earth Sciences (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Microbiology (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Accessories For Mixers (AREA)

Description

(54) TREATMENT OF SEWAGE IN A SEWER (71) We, BOC INTERNATIONAL LI MITED, of Hammersmith House, London W6 9DX, England, an English company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to the treatment of sewage in a sewer and is an improvement in, or modification of, the invention disclosed in our United Kingdom patent specification No 1 452 961.
It is proposed in the above numbered specification to treat sewage in a sewer by injecting oxygen-rich gas under pressure into the sewer system. More specifically, the gas is injected through a pipe (having orifices therein) into the sewage flowing through the sewer, into the volute of a pump for driving sewage through a rising main sewer or into a sump in which the sewage is contained prior to its being pumped through the sewer.
The present invention resides in a method of treating sewage in a sewer wherein oxygen-rich gas is injected into the sewage through part of a reflux valve provided in the sewer, or at a location in the vicinity of such a valve where turbulence exists in the sewage by virtue of the flow of sewage through the valve.
By injecting the gas into a region of turbulence in the sewage the gas is readily broken up into a fine bubble form and mixed with the sewage, facilitating dissolution of the gas in the sewage.
The invention also resides in apparatus for treating sewage in a sewer comprising means for injecting oxygen-rich gas into the sewage through part of a reflux valve for location in the sewer or through means for location in the vicinity of such a valve whereat, in use, turbulence exists in the sewage by virtue of the flow of sewage through the valve.
The invention furthermore resides in a sewer provided with such apparatus.
The term "oxygen-rich gas" is used herein to mean oxygen or a gaseous mixture having a proportion of oxygen higher than that of air, preferably greater than 95% oxygen.
The gas may be injected into the sewage through a gas-permeable portion of the valve housing or of the wall of the sewer.
Alternatively, the valve may have a hollow valve member to define a chamber which is supplied with pressurised air or oxygen rich gas, a portion of the wall of such chamber being gas permeable to allow the gas to permeate through into the sewage flowing over the valve member. In any case, the gas-permeable portion may be provided by an element of porous or perforate material.
Preferred porous materials are non-ferrous sintered materials such as copper or bronze which have the advantage that bacterial slime tends not to adhere to them and clog their pores.
The pores or holes of any such element preferably have greatest transverse dimensions of 0.010 inch or less. It is also preferred that each such pore or hole is spaced from its neighbours by a distance substantially greater than the aforesaid transverse dimension, and most preferably by a distance of at least 0.030 inch, e.g.
0.060 inch or more, to minimise the likelihood of coalescence of bubbles of gas emerging from the pores or holes.
When the gas is substantially pure oxygen it is conveniently supplied to the sewage from a reservoir of liquid oxygen contained in a vacuum insulated evaporator, the liquid being evaporated by heat exchange with the ambient atmosphere.
In some methods according to the invention the concentration of dissolved oxygen in the sewage or the biochemical oxygen demand of the sewage may be monitored downstream of the point of gas injection, and the rate of gas injection adjusted in accordance with changes in the monitored value. Such adjustment may take place automatically using a control system, e.g. an analogue or digital computer, which receives signals from a dissolved oxygen meter and emits signals to actuate means for controlling the rate of flow of gas.
The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic representation of apparatus for injecting an oxygen-rich gas into sewage in a rising main sewer; Figure 2 is a schematic sectional view of the reflux valve of Figure 1; and Figure 3 is a schematic sectional view of a modified form of reflux valve.
Referring to Figure 1, there is shown a rising main sewer 10 leading from a pumping station 11. A sewage inlet 12 is provided to pass sewage to a sump 13. A pump 14 draws the sewage from the sump, pressurises the sewage and delivers it into the sewer conduit 10. A reflux valve 15 is provided in conduit 10 near pump 14 to prevent backflow of sewage into the pump.
Oxygen-rich gas is supplied under pressure through a line 17 and passes to a chamber 30 (Figure 2) adjoining the housing 31 of the reflux valve 15. The housing 31 has a porous plate 32 made of sintered bronze set into its wall which plate also defines part of the boundary of chamber 30. Oxygen-rich gas from the chamber permeates through the plate 32 and enters the sewage flowing through the valve in a fine bubble form. As the reflux valve acts as a constriction in the sewage flow, there is high velocity and a swirling motion created in the sewage. Such enforced turbulence assists in dissolving the gas in the sewage by breaking up the fine gas bubbles into even finer bubbles.
The gas, when substantially pure oxygen, is conveniently contained in liquid form in a conventional vacuum insulated evaporator (not shown) whereby the liquid is evaporated by heat exchange with the ambient atmosphere to provide a pressurised supply of gas to line 17.
The flow of gas is controlled by a solenoid operated valve 18 which is operated automatically to adjust the rate of flow through line 17 in accordance with variations in the value of the concentration of dissolved oxygen measured at the outfall 19 of the rising main by a dissolved oxygen meter 20.
In a typical example of a process according to the invention using apparatus of the type described above, sewage is pumped along the conduit 10 at a flow rate of 1 mgd and at a pressure of 3 atmospheres while substantially pure oxygen is supplied to the chamber 30 at a pressure of 5 atmospheres.
Oxygen in fine bubble form enters the sewage through porous plate 32 at a rate such that the dissolved oxygen content of sewage downstream of the oxygen injection point is of the order of 100 ppm.
Figure 3 illustrates a modified form of reflux valve for use with the apparatus of Figure 1. In this case the pivotted valve member 35 is hollow to define a chamber 41 which is fed with oxygen-rich gas via a passage provided through the hinge 42.
Porous plates 40 are set into the walls of the valve member through which the gas permeates to emerge in fine bubble form into the turbulent flow of sewage passing through the valve.
WHAT WE CLAIM IS: 1. A method of treating sewage in a sewer wherein oxygen-rich gas is injected into the sewage through part of a reflux valve provided in the sewer, or at a location in the vicinity of such a valve whereat turbulence exists in the sewage by virtue of the flow of sewage through the valve.
2. A method according to claim 1 wherein the gas is injected through a gas permeable portion of the valve housing or-of the wall of the sewer.
3. A method according to claim 1 wherein the gas is injected through a gas permeable portion of a movable valve member.
4. A method according to claim 2 or claim 3 wherein said gas permeable portion is provided by an element of porous or perforate material.
5. A method according to claim 4 wherein the pores or holes of said element have greatest transverse dimensions of 0.010 inch or less.
6. A method according to claim 4 or claim 5 wherein the pores or holes of said element are spaced apart by distances substantially greater than the greatest. transverse dimensions thereof.
7. A method according to any preceding claim wherein the gas is supplied to the sewage from a reservoir of liquid oxygen.
8. A method according to any preceding claim wherein the dissolved oxygen concentration or biochemical oxygen demand of the sewage is monitored downstream of the point of gas injection and the rate of gas injection is controlled in accordance with changes in the monitored value.
9. Apparatus for treating sewage in a sewer comprising means for injecting oxygen-rich gas into the sewage through part of a reflux valve for location in the sewer or through means for location in the. vicinity of such a valve whereat, in use, turbulence exists in the sewage by virtue of the flow of sewage through the valve.
10. Apparatus according to claim 9
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (19)

**WARNING** start of CLMS field may overlap end of DESC **. downstream of the point of gas injection, and the rate of gas injection adjusted in accordance with changes in the monitored value. Such adjustment may take place automatically using a control system, e.g. an analogue or digital computer, which receives signals from a dissolved oxygen meter and emits signals to actuate means for controlling the rate of flow of gas. The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic representation of apparatus for injecting an oxygen-rich gas into sewage in a rising main sewer; Figure 2 is a schematic sectional view of the reflux valve of Figure 1; and Figure 3 is a schematic sectional view of a modified form of reflux valve. Referring to Figure 1, there is shown a rising main sewer 10 leading from a pumping station 11. A sewage inlet 12 is provided to pass sewage to a sump 13. A pump 14 draws the sewage from the sump, pressurises the sewage and delivers it into the sewer conduit 10. A reflux valve 15 is provided in conduit 10 near pump 14 to prevent backflow of sewage into the pump. Oxygen-rich gas is supplied under pressure through a line 17 and passes to a chamber 30 (Figure 2) adjoining the housing 31 of the reflux valve 15. The housing 31 has a porous plate 32 made of sintered bronze set into its wall which plate also defines part of the boundary of chamber 30. Oxygen-rich gas from the chamber permeates through the plate 32 and enters the sewage flowing through the valve in a fine bubble form. As the reflux valve acts as a constriction in the sewage flow, there is high velocity and a swirling motion created in the sewage. Such enforced turbulence assists in dissolving the gas in the sewage by breaking up the fine gas bubbles into even finer bubbles. The gas, when substantially pure oxygen, is conveniently contained in liquid form in a conventional vacuum insulated evaporator (not shown) whereby the liquid is evaporated by heat exchange with the ambient atmosphere to provide a pressurised supply of gas to line 17. The flow of gas is controlled by a solenoid operated valve 18 which is operated automatically to adjust the rate of flow through line 17 in accordance with variations in the value of the concentration of dissolved oxygen measured at the outfall 19 of the rising main by a dissolved oxygen meter 20. In a typical example of a process according to the invention using apparatus of the type described above, sewage is pumped along the conduit 10 at a flow rate of 1 mgd and at a pressure of 3 atmospheres while substantially pure oxygen is supplied to the chamber 30 at a pressure of 5 atmospheres. Oxygen in fine bubble form enters the sewage through porous plate 32 at a rate such that the dissolved oxygen content of sewage downstream of the oxygen injection point is of the order of 100 ppm. Figure 3 illustrates a modified form of reflux valve for use with the apparatus of Figure 1. In this case the pivotted valve member 35 is hollow to define a chamber 41 which is fed with oxygen-rich gas via a passage provided through the hinge 42. Porous plates 40 are set into the walls of the valve member through which the gas permeates to emerge in fine bubble form into the turbulent flow of sewage passing through the valve. WHAT WE CLAIM IS:
1. A method of treating sewage in a sewer wherein oxygen-rich gas is injected into the sewage through part of a reflux valve provided in the sewer, or at a location in the vicinity of such a valve whereat turbulence exists in the sewage by virtue of the flow of sewage through the valve.
2. A method according to claim 1 wherein the gas is injected through a gas permeable portion of the valve housing or-of the wall of the sewer.
3. A method according to claim 1 wherein the gas is injected through a gas permeable portion of a movable valve member.
4. A method according to claim 2 or claim 3 wherein said gas permeable portion is provided by an element of porous or perforate material.
5. A method according to claim 4 wherein the pores or holes of said element have greatest transverse dimensions of 0.010 inch or less.
6. A method according to claim 4 or claim 5 wherein the pores or holes of said element are spaced apart by distances substantially greater than the greatest. transverse dimensions thereof.
7. A method according to any preceding claim wherein the gas is supplied to the sewage from a reservoir of liquid oxygen.
8. A method according to any preceding claim wherein the dissolved oxygen concentration or biochemical oxygen demand of the sewage is monitored downstream of the point of gas injection and the rate of gas injection is controlled in accordance with changes in the monitored value.
9. Apparatus for treating sewage in a sewer comprising means for injecting oxygen-rich gas into the sewage through part of a reflux valve for location in the sewer or through means for location in the. vicinity of such a valve whereat, in use, turbulence exists in the sewage by virtue of the flow of sewage through the valve.
10. Apparatus according to claim 9
wherein the gas can be injected through a gas permeable portion of the valve housing or of the wall of the sewer.
11. Apparatus according to claim 9 wherein the gas can be injected through a gas permeable portion of a movable valve member.
12. Apparatus according to claim 10 or claim 11 wherein said gas permeable portion is provided by an element of porous or perforate material.
13. Apparatus according to claim 12 wherein the pores or holes of said element have greatest transverse dimensions of 0.010 inch or less.
14. Apparatus according to claim 12 or claim 13 wherein the pores or holes of said element are spaced apart by distances substantially greater than the greatest transverse dimensions thereof.
15. Apparatus according to any one of claims 9 to 12 comprising a gas supply in the form of a reservoir of liquid oxygen.
16. Apparatus according to any one of claims 9 to 15 comprising means for monitoring the dissolved oxygen concentration or biochemical oxygen demand of sewage at a selected point in the sewer and means for controlling the rate of gas injection in accordance with changes in the monitored value.
17. A sewer provided with apparatus according to any one of claims 9 to 16.
18. A method of treating sewage substantially as hereinbefore described with reference to the accompanying drawings.
19. Apparatus for treating sewage substantially as hereinbefore described with reference to the accompanying drawings.
GB10540/77A 1977-03-11 1977-03-11 Treatment of sewage in a sewer Expired GB1595068A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB10540/77A GB1595068A (en) 1977-03-11 1977-03-11 Treatment of sewage in a sewer
AU34078/78A AU520567B2 (en) 1977-03-11 1978-03-10 Sewage treatment

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB10540/77A GB1595068A (en) 1977-03-11 1977-03-11 Treatment of sewage in a sewer

Publications (1)

Publication Number Publication Date
GB1595068A true GB1595068A (en) 1981-08-05

Family

ID=9969709

Family Applications (1)

Application Number Title Priority Date Filing Date
GB10540/77A Expired GB1595068A (en) 1977-03-11 1977-03-11 Treatment of sewage in a sewer

Country Status (2)

Country Link
AU (1) AU520567B2 (en)
GB (1) GB1595068A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2590246A1 (en) * 1985-11-20 1987-05-22 Screg Routes & Travaux Device for the oxygenation of lagoon treatment effluents

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2590246A1 (en) * 1985-11-20 1987-05-22 Screg Routes & Travaux Device for the oxygenation of lagoon treatment effluents

Also Published As

Publication number Publication date
AU520567B2 (en) 1982-02-11
AU3407878A (en) 1979-09-13

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