APPARATUS AND METHOD FOR ADVANCED NITROGEN AND PHOSPHORUS REMOVAL OF DOMESTIC SEWAGE BASED ON DEAMOX IN AOAO PROCESS WITH SLUDGE DOUBLE-REFLUX

Abstract

A method for advanced nitrogen and phosphorus removal of domestic sewage based on DEAMOX in AOAO process with sludge double-reflux is disclosed. The method comprises allowing domestic sewage and returned sludge of the secondary sedimentation tank (3) to enter the anaerobic zone (2.1) of the AOAO reactor (2), firstly performing partial denitrification by the denitrifying bacteria, reducing nitrate-nitrogen in the returned sludge to nitrite-nitrogen, then converting ammonia-nitrogen and nitrite-nitrogen into nitrogen by anammox bacteria, and phosphate accumulating bacteria and denitrifying phosphate accumulating organisms performing anaerobic phosphate release and storing internal carbon source; then allowing part of the mixed liquid to enter the intermediate aerobic zone (2.2) of the AOAO bioreactor (2) to carry out phosphate uptake and nitrification reaction, allowing another part of the mixed liquid to enter the anoxic zone (2.3) of the AOAO bioreactor (2), at same time allowing all the mixed liquid of the intermediate aerobic zone (2.2) and part of returned sludge of the secondary sedimentation tank (3) to enter the anoxic zone (2.3), using the internal carbon source stored in the anaerobic compartment and the internal carbon source in the returned sludge to carry out partial denitrification, anammox, denitrifying dephosphatation, and then allowing the mixed liquid to enter the post aerobic zone (2.4) and subsequently enter the secondary sedimentation tank (3) for mud-water separation. An apparatus for advanced nitrogen and phosphorus removal of domestic sewage based on DEAMOX in AOAO process with sludge double-reflux is also disclosed.

Claims

1. An apparatus for advanced nitrogen and phosphorus removal of domestic sewage based on DEAMOX in AOAO process with sludge double-reflux, characterized in that, the apparatus comprises a raw water tank, an AOAO bioreactor and a secondary sedimentation tank which are connected in sequence; the AOAO bioreactor sequentially comprises an anaerobic zone, an intermediate aerobic zone, an anoxic zone and a post aerobic zone; the raw water tank is connected to a first compartment of the anaerobic zone through an influent pump, the anaerobic zone is connected to the intermediate aerobic zone, a last compartment of the anaerobic zone is connected to a first compartment of the anoxic zone by crossing a sludge pump, the intermediate aerobic zone is connected to the anoxic zone, the anoxic zone is connected to the post aerobic zone, and the post aerobic zone is connected to the secondary sedimentation tank via an overflow pipe; a bottom of the secondary sedimentation tank is connected to a first compartment of the anaerobic zone through a first sludge reflux pump, the bottom of the secondary sedimentation tank is connected to the first compartment of the anoxic zone through a second sludge reflux pump, an effluent from the secondary sedimentation tank is discharged through a drainage pipe, and a sludge is discharged from a sludge pipe; the anaerobic zone and the anoxic zone are equipped with an agitator respectively, a aeration pump is respectively connected to an aeration sand block in the post aerobic zone and the intermediate aerobic zone through a rotormeter; an anammox filler is placed in the anaerobic zone and the anoxic zone respectively with a filling ratio of 30%-40%, a suspended polyethylene biological filler is placed in the intermediate aerobic zone with a specific surface density of 450-500 m.sup.2/m.sup.3 and a filling ratio of 30%-40%.

2. A method of applying the apparatus of claim 1, characterized by comprising the following steps of: 1) allowing domestic sewage from the raw water tank to enter a first compartment of the anaerobic zone of the AOAO bioreactor via the influent pump, at the same time allowing part of returned sludge pumped by the first sludge reflux pump from the bottom of the secondary sedimentation tank to enter the first compartment of the anaerobic zone of the AOAO bioreactor, and controlling a hydraulic retention time in the anaerobic zone to be 2-4 h, using part of organic matter in influent water by the denitrifying bacteria to perform partial denitrification, and then using ammonia-nitrogen and nitrite-nitrogen by anammox bacteria on the anammox filler in the anaerobic zone to carry out anammox reaction, followed by storing internal carbon source by phosphate accumulating bacteria and denitrifying phosphate accumulating bacteria and performing anaerobic phosphate release reaction; 2) allowing part of a first mixed liquid from an last compartment of the anaerobic zone to enter the aerobic zone, and controlling dissolved oxygen concentration to be 2-4 mg/L by controlling the rotormeter and the hydraulic retention time in the aerobic zone to be 3-4 h, carrying out aerobic phosphate uptake by phosphate accumulating bacteria, and completing nitrification reaction by nitrifying bacteria; 3) allowing part of the first mixed liquid from a last compartment of the anaerobic zone to enter a first compartment of the anoxic zone via crossing the sludge pump, allowing all of a second mixed liquid from an last compartment of the intermediate aerobic zone to enter the first compartment of the anoxic zone, and at the same time allowing part of returned sludge pumped by the second sludge reflux pump from the bottom of the secondary sedimentation tank to enter the first compartment of the anoxic zone, controlling an average hydraulic retention time in the anoxic zone to be 5-7 h, denitrifying phosphate accumulating bacteria playing a role in the anoxic zone, using the internal carbon source stored in the anaerobic zone and the internal carbon source in the returned sludge of the secondary sedimentation tank to carry out denitrifying dephosphatation and partial denitrification, reducing nitrate-nitrogen produced in the intermediate aerobic zone to nitrite-nitrogen, carrying out anammox reaction of ammonia-nitrogen with nitrite-nitrogen to achieve advanced nitrogen removal; 4) allowing a third mixed liquid from the anoxic zone to enter the post aerobic zone to oxidize ammonia-nitrogen in the third mixed liquid and strip nitrogen gas generated in the anoxic zone, while improving sludge settling performance; 5) allowing a fourth mixed liquid from the post aerobic zone to enter the secondary sedimentation tank through the overflow pipe to achieve the purpose of mud-water separation, discharging a supernatant in the secondary sedimentation tank via the drainage pipe, returning a sludge at the bottom of the secondary sedimentation tank to the first compartment of the anaerobic zone via the first sludge reflux pump, which has a sludge reflux ratio of 70%-100%, and the sludge at the bottom of the second settling tank is returned to the first compartment of the anoxic zone by the second sludge return pump, which has a sludge reflux ratio of 70%-100%; maintaining a concentration of activated sludge in the AOAO bioreactor at 3000-4000 mg/L, controlling floc sludge retention time at 10-15 d.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is an apparatus for advanced nitrogen and phosphorus removal of AOAO sewage based on DEAMOX sludge double-reflux.

[0021] Reference numerals in FIG. 1 are listed as follows:

[0022] 1—raw water tank; 1.1—influent pump; 2—AOAO bioreactor; 2.1—anaerobic zone; 2.2—intermediate aerobic zone; 2.3—anoxic zone; 2.4—post aerobic zone; 2.5—sludge pump; 2.6—aeration sand block; 2.7—agitator; 2.8—aeration pump; 2.9—rotormeter; 2.10—overflow pipe; 2.11—anammox filler; 2.12—polyethylene biological filler; 3—secondary sedimentation tank; 3.1—first sludge reflux pump; 3.2—second sludge reflux pump; 3.3—drainage pipe; 3.4—sludge pipe.

DETAILED DESCRIPTION

[0023] With reference to FIG. 1, the embodiment of the present invention is described in detail:

[0024] 1) allowing domestic sewage from the raw water tank (1) to enter a first compartment of the anaerobic zone (2.1) of the AOAO bioreactor (2) via the influent pump (1.1), at the same time allowing part of returned sludge pumped by the first sludge reflux pump (3.1) from the bottom of the secondary sedimentation tank (3) to enter the first compartment of the anaerobic zone (2.1) of the AOAO bioreactor (2), and controlling the hydraulic retention time in the anaerobic zone to be 2-4 h, using part of the organic matter in the influent water by the denitrifying bacteria to perform partial denitrification, and then using ammonia-nitrogen and nitrite-nitrogen by anammox bacteria on the anammox filler (2.11) in the anaerobic zone (2.1) to carry out anammox reaction, and then storing internal carbon source by phosphate accumulating bacteria and denitrifying phosphate accumulating organisms and being carried out anaerobic phosphate release reaction;

[0025] 2) allowing part of the mixed liquid to enter the aerobic zone (2.2) from the end of the anaerobic zone (2.1), and controlling the hydraulic retention time in the aerobic zone to be 3-4 h, carrying out aerobic phosphate uptake by phosphate accumulating bacteria, and completing nitrification reaction by nitrifying bacteria;

[0026] 3) allowing part of the mixed liquid to enter a first compartment of the anoxic zone (2.3) from the end of the anaerobic zone (2.1) via crossing the sludge pump (2.5), allowing all the aerobic mixed liquid to enter the first compartment of the anoxic zone (2.3) from the end of the intermediate aerobic zone (2.2), and at the same time allowing part of returned sludge pumped by the second sludge reflux pump (3.2) from the bottom of the secondary sedimentation tank (3) to enter the first compartment of the anoxic zone (2.3), controlling the average hydraulic retention time in the anoxic zone (2.3) to be 5-7 h, denitrifying phosphate accumulating organisms playing a role in the anoxic zone (2.3), using the internal carbon source stored in the anaerobic compartment and the internal carbon source in the returned sludge of the secondary sedimentation tank to carry out denitrifying dephosphatation and partial denitrification, reducing nitrate-nitrogen produced in the intermediate aerobic zone (2.2) to nitrite-nitrogen, carrying out anammox reaction of ammonia-nitrogen with nitrite-nitrogen to achieve advanced nitrogen removal;

[0027] 4) allowing the mixed liquid to enter the post aerobic zone (2.4) from the anoxic zone (2.3) to oxidize ammonia-nitrogen in the mixed liquid and strip nitrogen gas generated in the anoxic zone (2.3), while improving the sludge settling performance;

[0028] 5) allowing the mixed liquid to enter the secondary sedimentation tank (3) from the post aerobic zone (2.4) through the overflow pipe (2.10) to achieve the purpose of mud-water separation, discharging the supernatant in the secondary sedimentation tank (3) via the drainage pipe (3.3), returning the sludge at the bottom of the secondary sedimentation tank (3) to the first compartment of the anaerobic zone (2.1) via first sludge reflux pump (3.1), the sludge reflux ratio is 70%-100%, and returning the sludge at the bottom of the secondary sedimentation tank (3) to the first compartment of the anoxic zone (2.3) by the second sludge return pump (3.2), which has a sludge reflux ratio of 70%-100%;

[0029] maintaining the concentration of activated sludge in the AOAO bioreactor at 3000-4000 mg/L, controlling the floc sludge retention time at 10-15 d.

[0030] Taking domestic sewage from the family area of a university in Beijing as the treatment object, the performance of this system for nitrogen and phosphorus removal was investigated.

TABLE-US-00001 COD NH.sub.4.sup.+—N TN PO.sub.4.sup.3−—P (mg/L) (mg/L) (mg/L) (mg/L) Domestic Sewage 180-260 40-50 50-60 3-6 (influent) Effluent 35-45 0-3  6-10 0.1-0.5 (discharge)

[0031] The test results show that the effluent meets the first level A criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002) under the stable operation of the system.