GB2241697A

GB2241697A - Aeration of sewage

Info

Publication number: GB2241697A
Application number: GB8927516A
Authority: GB
Inventors: Derek Lyonel Herbertson
Original assignee: D L HERBERTSON Ltd
Current assignee: D L HERBERTSON Ltd
Priority date: 1989-12-06
Filing date: 1989-12-06
Publication date: 1991-09-11
Anticipated expiration: 2009-12-06
Also published as: GB2241697B; GB8927516D0

Abstract

An aeration unit affording the purification of sewage comprising essentially of an aeration and or primary distribution zone; a vertical sewage droplet or spray zone, and a settlement and or accumulation zone. The following ancillary items which may or may not be fundamental to the successful performance of the unit: 1) A recirculation pump, pipes and valves together with a recirculation capacity control system. 2) Air induction fans and ducting complete with compressor heat recovery system (for de-icing). 3) Compressors complete with motors silencers providing compressed air for the primary aeration system. 4) Dissolved oxygen monitoring. 5) Scum removal and outlet system. 6) Supporting steelwork and external enclosure. 7) Electrical control equipment and wiring and cableing. <IMAGE>

Description

MODULAR AERATION UNIT 1. This invention relates to a modular aeration unit for the purification of sewage.

2. The aeration of sewage, in order to purify it, by the reduction of the Biological Oxygen Demand is an established method of treating sewage. The invention described offers a different method of presenting air to the sewage namely by maximising the surface area of the sewage and bringing it in contact with a surplus of air. It is intended that the invention will provide a more economic (in terms of capital cost and power consumption) means of treating sewage.

3. According to the present invention, there is provided, an aeration tank, complete with a means of aerating the sewage and distribution to the periphery; a main sewage tank having a means of creating a vertical droplet zone, and a accumulation zone at the base complete with scum draw-off and outlet weir box; recirculation pump air compressors; air induction fans and control equipment.

4. A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which Figure 1 shows in perspective the external appearance of the modular aeration unit.

Figure 2 illustrates in diagrammatic form, the operation and main components of the modular aeration unit.

Figure 3 indicates an arrangement of the equipment described.

Referring to the drawings Figures 1 and 2 sewage and return activated sludge is drawn into the suction or inlet manifold (together with a proportion of liquor from the accumulation zone which is to be recirculated). The recirculation pump then delivers the mixed liquor to the aeration tank. The amount of liquor discharged being regulated by a control valve and flowmeter.

The liquid is discharged into the centre of the aeration tank and leaves the tank via a peripheral weir. Porous dome aeration diffusers mounted in the base of the aeration tank inject into the sewage air being provided by blower type compressors.

The liquid is delivered by gravity to a peripheral distribution box at the top of the main sewage tank and then to V-notched channels (or similar means) to produce a large number of small vertical jets of liquor. Fresh air is induced into the vessel by means of fans which enhances the oxygen transfer rate to the sewage and hence the purification rate. The air is exhausted from the unit through a mesh grille on the top of the unit.

Warm air may be drawn from the area around the blowers in order to de-ice the droplet zone in winter.

The liquid is accumulated at the base of the tank the water level being regulated by the weir within the outlet box. A valved pipe connects the accumulation zone sump with the outlet box. Scum which collects at the water surface may be drawn off by increasing the water level (closing the outlet valve) and allowing the scum to flow over a weir into a secondary outlet box.

Access in the way of ladders, platforms and access doors are provided to all parts of the plant which require maintenance and inspection.

Claims

1) An Aeration Unit generally as indicated on drawing number J007/01 (Fig 3) and comprising : i) AERATION TANK (aeration and primary zone) Small capacity tank suitable for containing sewage complete with air diffuser cones and air distribution pipework; peripheral outlet weir; open mesh walkway cover having accessways.

ii) MAIN SEWAGE TANK (Vertical Droplet Zone & BR< Settlement and or Accumulation Zone) Large capacity tank suitable for containing sewage complete with distribution system (ie peripheral distribution box and means of creating a vertical sewage droplet zone), access door with inspection window, open mesh flooring, outlet weir box, scum removal box ,recirculation sump, drain and outlet sump, access platforms and ladders, sewage accumulation zone, R.S.Section baseframe with levelling facilities.

iii) ANCILLARY EQUIPMENT RECIRCULATION PUMP complete with pipework, valves, suction manifold, control valve and flowmeter; AIR INDUCTION FANS complete with ducting, flexible connections, dampers, compressor waste heat recuperation system; COMPRESSORS complete with motors, belt drive, baseframe, inlet and outlet silencer, interconnecting pipework; ELECTRICAL AND CONTROL EQUIPMENT complete with control consul, switchgear, instrumentation (including dissolved oxygen equipment) wiring and cabling.

iv) ENCLOSURE ROLLED STEEL SECTION FRAMEWORK complete with purl ins, bracing and fastenings; WEATHERTIGHT LOUVRED CLADDING for the base of the enclosure complete with access doors; CLADDING complete with flashings, fixings and fastenings for the side walls and the roof of the enclosure.

2) An aeration unit as claimed in Claim 1) wherein the Biological Oxygen Demand of influent sewage is reduced to a satisfactory extent.

3) An aeration unit as claimed in Claim 1) wherein an inflow of sewage and an inflow of return activated sludge is accepted and a effluent of treated sewage is discharged.

4) An aeration unit as claimed in Claim 1) wherein there is recirculation of the contained sewage.

5) An aeration unit as Claimed in Claim 1) which has an external enclosure affording a safe and suitable access for maintenance.

6) An aeration unit as Claimed in Claims 1),2),3) with or without an aeration or primary distribution zone.

7) An aeration unit as Claimed in Claims 1),2),3) with or without: i)an enclosure.

ii)either or any of the ancillary items listed above.

iii)either or any of the following: access doors, open mesh flooring, outlet weir box, scum removal box ,recirculation sump, drain and outlet sump, access platforms and ladders, sewage accumulation zone, R.

S.Section baseframe with levelling facilities.