GB1567143A

GB1567143A - Method and apparatus for the biological degradatin of effluent

Info

Publication number: GB1567143A
Application number: GB18495/78A
Authority: GB
Original assignee: Mono Pumps Ltd
Current assignee: NOV Process and Flow Technologies UK Ltd
Priority date: 1978-05-09
Filing date: 1978-05-09
Publication date: 1980-05-14

Description

(54) METHOD AND APPARATUS FOR THE BIOLOGICAL DEGRADATION OF EFFLUENT (71) We, MONO PUMPS (ENGINEERING) LWTED, a British Company of Arnfield Works, Audenshaw, Manchester, England 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: The present invention relates to a method and apparatus for treating whole raw sewage effluent by biological degradation.

Various proposals have been made for the treatment of sewage and one particularly compact system has been described and claimed in British Patent No.

1,328,812. According to this Patent, whole raw sewage effluent is treated by macerating the whole raw sewage effluent, passing it to a vessel containing submerged contact media comprising a bed of randomly arranged discrete pieces of plastics material, passing the effluent through the media, passing air through the effluent and media and withdrawing treated effluent from the vessel at a point above the bed.

Such a method is perfectly satisfactory in the majonity of cases However, in certain circumstances, it has been found that the quality of the resulting treated fluid is not sufficiently high.

It is now proposed, according to the present invention, to provide a method of treating whole raw sewage effluent including the steps of macerating the whole raw sewage effluent, passing it to a vessel contanning submerged contact media comprising a bed of randomly submerged contact media comprising a bed of randomly arranged discrete pieces of plastics material, passing the effluent through the media, passing air through the effluent and media, withdrawing treated effluent from the vessel at a point above the bed, passing the ed9utnt to a main settlement tank, settling sludge out of the treated effluent in the settlement tank and returning some of the settled sludge to said vessel containing submerged contact media.

Preferably the air is fed upwardly through the vessel and in a preferred arrangement the effluent is also fed to the vessel at the lower region thereof. Bio- logically purified effluent can leave the top of the vessel and pass to the settlement tank, and the sludge from the settlement tank can be fed back to the vessel as activated sludge.

The effluent from the settlement tank can, if desired, be passed to at least one more stage, wherein the steps of the method, with the exception of the maceration, are repeated. The effluent can, alternatively, be passed from the first vessel to a second vessel containing submerged contact media and through which air is passed and thence to a settlement tank.

The macerated effluent is advantageously fed to a primary settlement tank in which some of the solids are withdrawn before being fed to the vessel containing submerged contact media. The sludge from the primary settlement tank and from the main settlement tank can be fed to a sludge digester.

The invention also provides whole raw sewage effluent treatment apparatus comprising a macerator, at least one vessel, contact media comprising a bed of randomly arranged discrete pieces of plastics material within said vessel, means to supply effluent from said macerator to said vessel, means for supplying air to the vessel, whereby said effluent and air pass through said bed, means to withdraw treated effluent from said vessel at a local tion in said vessel above said media, such that said media is submerged; a settlement tank arranged downstream of said vessel to receive treated effluent from said vessel and means to return at least some of the sludge settled in the settlement tank to the vessel containing contact media.

Preferably the macerator is a combined macerator and pump as described in British Patent No. 970,667.

In a convenient construction, the contact media is preferably of the type described in British Patent No. 1,479,656.

In order that the invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawing, in which the sole Figure is a schematic cross-section through one embodiment of apparatus according to the invention.

The apparatus illustrated in the drawing includes a sump 10 for the raw sewage effluent to be treated, and a combined pump and macerator 11 of the type described in British Patent Specification No.

970,667. This draws the raw sewage effluent via line 12 and pumps the macerated effluent via line 13 into a primary settlement tank 14.

Mounted adjacent this settlement tank is a treatment vessel 15 which is packed with discrete pieces of plastics media such as that illustrated in British Patent Specification No. 1,479,656. The vessel 15 is divided by a partition wall 16 into two halves 17 and 18, the packing in the two halves being illustrated by the cross-hatching in the drawing. A grid 19 extends across each vessel at a location spaced above the bottom and the wall 16 is continued in the bottom section by a grid 20.

Two air valves 21 and 22 are provided and these are advantageously of the type sold under the Registered Trade Mark "DRAVO".

Adjacent the vessel 15 is a main settlement tank 23 having a central inlet chamber 24 into which material treated in vessel 15 is fed via line 25. Treated effluent from the settlement tank 23 can leave via a launder in the settlement tank and line 26.

A sludge digester 27 is placed adjacent the main settlement tank 23 and is provided at its lower region with an air valve 28 again preferably of the "DRAVO" type.

The air valves 21, 22 and 28 are each fed via lines 29, 30 and 31, from an air blower 32.

The main settlement tank 23 is provided with a vertical line 33 and a pump (not shown) which will draw the sludge from the bottom of the settlement tank and this will be fed via line 34 and 35 to the inlet half 17 of the treatment vessel 15, and via lines 36 and 37 to the primary settlement tank 14 and the sludge digester 27 respectively. The sludge from the primary tank 14 can be fed via line 38 and a pump (not shown) to the digester 27.

In operation, raw sewage sludge is drawn up by the pump I macerator 11 through line 12, and the macerated sludge is fed via line 13 to the primary settlement tank 14.

Some of the heavier solids are settled out in this settlement tank. The remainder of the material entering primary settlement tank 14 leaves via line 39 to enter the inlet half 17 of the treatment vessel 15. The arrangement of the inlet line 39 to this vessel and the outlet line 25 is such that the plastics media in the two halves 17 and 18 is always submerged. This fluid sewage flows downwardly in the half 17, and through the grid 19, to the right through grid 20, upwardly through grid 19 again into the second half 18 in which it again passes over the plastics media.

During the passage in the halves 17 and 18 over the plastics media, aerobic fermentation takes place, this being brought about by air supplied via valves 21 and 22.

The treated effluent flows via line 25 into the settlement tank 23 and sludge is collected in the bottom of the vessel 23, while the clear purified liquid leaves via line 26.

In order to improve the operation, according to the invention, some of the sludge which is pumped up via lines 33 is fed via lines 34 and 35 back to the inlet side of the treatment vessel and brings about an activated sludge process also which improves the cleaning effect in the treatment chamber. A certain proportion of the activated sludge can also be fed into the primary settlement vessel 14.

As indicated, the sludge which collects in the bottom of the vessel 14, and some of the remaining sludge which is not used in the reactivated sludge process is fed via line 37 to the sludge digester 27 in which the sludge is digested using air via valve 28. Some of the sludge can be fed back via line 40 to the sump 10.

WHAT WE CLAIM IS: 1. A method of treating whole raw sewage effluent including the steps of macerating the whole raw sewage effluent, passing it to a vessel containing submerged contact media comprising a bed of randomly arranged discrete pieces of plastics material, passing the effluent through the media, passing air through the effluent and media, withdrawing treated effluent from the vessel at a point above the bed, passing the effluent to a main settlement tank settling sludge out of the treated effluent in the settlement tank and returning some of the settled sludge to said vessel containing submerged contact media.

2. A method according to claim 1, wherein the macerated whole raw sewage

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Claims

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sludge settled in the settlement tank to the vessel containing contact media.

Preferably the macerator is a combined macerator and pump as described in British Patent No. 970,667.

In a convenient construction, the contact media is preferably of the type described in British Patent No. 1,479,656.

In order that the invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawing, in which the sole Figure is a schematic cross-section through one embodiment of apparatus according to the invention.

The apparatus illustrated in the drawing includes a sump 10 for the raw sewage effluent to be treated, and a combined pump and macerator 11 of the type described in British Patent Specification No.

970,667. This draws the raw sewage effluent via line 12 and pumps the macerated effluent via line 13 into a primary settlement tank 14.

Mounted adjacent this settlement tank is a treatment vessel 15 which is packed with discrete pieces of plastics media such as that illustrated in British Patent Specification No. 1,479,656. The vessel 15 is divided by a partition wall 16 into two halves 17 and 18, the packing in the two halves being illustrated by the cross-hatching in the drawing. A grid 19 extends across each vessel at a location spaced above the bottom and the wall 16 is continued in the bottom section by a grid 20.

Two air valves 21 and 22 are provided and these are advantageously of the type sold under the Registered Trade Mark "DRAVO".

Adjacent the vessel 15 is a main settlement tank 23 having a central inlet chamber 24 into which material treated in vessel 15 is fed via line 25. Treated effluent from the settlement tank 23 can leave via a launder in the settlement tank and line 26.

A sludge digester 27 is placed adjacent the main settlement tank 23 and is provided at its lower region with an air valve 28 again preferably of the "DRAVO" type.

The air valves 21, 22 and 28 are each fed via lines 29, 30 and 31, from an air blower 32.

The main settlement tank 23 is provided with a vertical line 33 and a pump (not shown) which will draw the sludge from the bottom of the settlement tank and this will be fed via line 34 and 35 to the inlet half 17 of the treatment vessel 15, and via lines 36 and 37 to the primary settlement tank 14 and the sludge digester 27 respectively. The sludge from the primary tank 14 can be fed via line 38 and a pump (not shown) to the digester 27.

In operation, raw sewage sludge is drawn up by the pump I macerator 11 through line 12, and the macerated sludge is fed via line 13 to the primary settlement tank 14.

Some of the heavier solids are settled out in this settlement tank. The remainder of the material entering primary settlement tank 14 leaves via line 39 to enter the inlet half 17 of the treatment vessel 15. The arrangement of the inlet line 39 to this vessel and the outlet line 25 is such that the plastics media in the two halves 17 and 18 is always submerged. This fluid sewage flows downwardly in the half 17, and through the grid 19, to the right through grid 20, upwardly through grid 19 again into the second half 18 in which it again passes over the plastics media.

During the passage in the halves 17 and 18 over the plastics media, aerobic fermentation takes place, this being brought about by air supplied via valves 21 and 22.

The treated effluent flows via line 25 into the settlement tank 23 and sludge is collected in the bottom of the vessel 23, while the clear purified liquid leaves via line 26.

In order to improve the operation, according to the invention, some of the sludge which is pumped up via lines 33 is fed via lines 34 and 35 back to the inlet side of the treatment vessel and brings about an activated sludge process also which improves the cleaning effect in the treatment chamber. A certain proportion of the activated sludge can also be fed into the primary settlement vessel 14.

As indicated, the sludge which collects in the bottom of the vessel 14, and some of the remaining sludge which is not used in the reactivated sludge process is fed via line 37 to the sludge digester 27 in which the sludge is digested using air via valve 28. Some of the sludge can be fed back via line 40 to the sump 10.

WHAT WE CLAIM IS:

1. A method of treating whole raw sewage effluent including the steps of macerating the whole raw sewage effluent, passing it to a vessel containing submerged contact media comprising a bed of randomly arranged discrete pieces of plastics material, passing the effluent through the media, passing air through the effluent and media, withdrawing treated effluent from the vessel at a point above the bed, passing the effluent to a main settlement tank settling sludge out of the treated effluent in the settlement tank and returning some of the settled sludge to said vessel containing submerged contact media.

2. A method according to claim 1, wherein the macerated whole raw sewage

effluent is passed into a primary settlement tank prior to passing into the vessel containing submerged contact media.

3. A method according to claim 2, wherein the sludge collected in the primary settlement tank and the remainder of the sludge contained in the main settlement tank which is not returned to the vessel containing submerged contact media are fed to a sludge digester.

4. A method of treating whole raw sewage effluent substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

6. Whole raw sewage effluent treatment apparatus, comprising a macerator, at least one vessel, contact media comprising a bed of randomly arranged discrete pieces of plastics material within said vessel, means to supply effluent from said macerator to said vessel, means for supplying air to the vessel, whereby said effluent and air pass through said bed, means to withdraw treated effluent from said vessel at a location in said vessel above said media, such that said media is submerged, a settlement tank arranged downstream of said vessel to receive treated effluent from said vessel and means to return at least some of the sludge settled in the settlement tank to the vessel containing contact media.

7. Apparatus acording to claim 6, and including a primary settlement tank positioned to receive macerated whole raw sewage from the macerator whereby this macerated sewage can be settled and the liquor therefrom can be fed to said vessel containing contact media.

8. Apparatus according to claim 6 or 7 and including a sludge digester tank and means to feed sludge from the primary and main settlement tanks to the digester.

9. Whole raw sewage effluent treatment apparatus substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.