CN110217892B

CN110217892B - Sewage nitrogen and phosphorus removal process based on integrated biochemical reaction tank

Info

Publication number: CN110217892B
Application number: CN201910351530.3A
Authority: CN
Inventors: 吴英挺
Original assignee: Huangbao Fujian Environmental Protection Engineering Investment Co ltd
Current assignee: Huangbao Fujian Environmental Protection Engineering Investment Co ltd
Priority date: 2019-04-28
Filing date: 2019-04-28
Publication date: 2020-07-03
Anticipated expiration: 2039-04-28
Also published as: CN110217892A

Abstract

The invention relates to the technical field of sewage treatment, and particularly discloses a sewage nitrogen and phosphorus removal process based on an integrated biochemical reaction tank, wherein sewage after sand removal enters an anaerobic tank A and is mixed with high-concentration nitrogen removal sludge reflowing from an anoxic tank, and mixed liquid enters an anaerobic tank B under the condition of no molecular oxygen and combined oxygen; phosphorus-accumulating bacteria release phosphorus in the anaerobic pool B; the inlet mixed liquid enters a main aeration tank to finish phosphorus absorption, organic carbon degradation and ammonia nitrogen nitration; one sequencing batch tank is used as effluent of a settling zone to be discharged, and mixed liquor of the main aeration tank enters the other sequencing batch tank to carry out anoxic and aerobic cyclic reaction; and the mixed liquid after the anoxic and aerobic cyclic reaction flows back to the sludge-water separation tank, the concentrated sludge in the sludge-water separation tank is sent to the anoxic tank, and is sent to the anaerobic tank A after denitrification in the anoxic tank, and the circulation is performed in sequence. The invention has high sludge concentration and strong impact load resistance, can be suitable for treating organic wastewater with various inlet water qualities, and the effluent quality index reaches the national discharge first-grade A standard.

Description

Sewage nitrogen and phosphorus removal process based on integrated biochemical reaction tank

Technical Field

The invention relates to the technical field of sewage treatment, in particular to a sewage nitrogen and phosphorus removal process based on an integrated biochemical reaction tank.

Background

Biological phosphorus removal is achieved by utilizing microorganisms of phosphorus accumulating bacteria, which can absorb phosphorus from the external environment in excess and in quantity exceeding the physiological needs of the microorganisms, and the phosphorus is stored in the bacteria in a polymerized form to form high-phosphorus sludge to be discharged out of a system, so that the effect of removing phosphorus from sewage is achieved. Under anaerobic conditions (DO ═ 0, NO3 ═ 0), ATP in the polyphosphate accumulating organisms is hydrolyzed, releasing H2PO4, forming AOP and also releasing energy. Therefore, the phosphorus-accumulating bacteria has the functions of releasing H3PO4 under anaerobic conditions and excessively absorbing H3PO4 under aerobic conditions, and the biological phosphorus removal is to develop a technology and a process for removing phosphorus from sewage by utilizing the functions of the phosphorus-accumulating bacteria.

Meanwhile, a large amount of experimental data have completely proved that in the biological phosphorus removal process, activated sludge which releases phosphate in an anaerobic manner has strong phosphorus absorption capacity in an aerobic state, that is, the anaerobic release of phosphorus is a precondition for aerobic phosphorus absorption and phosphorus removal, but the aerobic phosphorus absorption capacity of the sludge can not be enhanced by the anaerobic release of all phosphorus.

Chinese patent publication (CN107285463A) discloses a MSBR (moving bulk biofilm reactor) nitrogen and phosphorus removal process based on MBBR (moving bulk biofilm reactor), which adopts a nitrogen and phosphorus removal system, wherein the system comprises a sludge concentration zone, a pre-anoxic zone, an anaerobic zone, an anoxic zone, an aerobic MBBR zone, a sequencing batch reaction zone I and a sequencing batch reaction zone II, as shown in figure 1, sewage firstly enters the anaerobic zone and is mixed with return sludge pumped from the pre-anoxic zone, sludge rich in phosphorus enters the anoxic zone for denitrification after phosphorus release reaction in the anaerobic zone, then mixed liquid in the anoxic zone enters the aerobic MBBR zone and enters the sequencing batch reaction zone I or the sequencing batch reaction zone II after organic matter degradation, nitrification and phosphorus absorption reaction, organic matter in the sewage is further degraded in the sequencing batch reaction zone I or the sequencing batch reaction zone II and is precipitated and separated at the same time, supernatant after sludge concentration is discharged into the aerobic MBBR zone from the upper part of the sludge concentration zone to obtain concentrated sludge which enters the pre-anoxic zone, further consumes the dissolved oxygen therein, and creates good conditions for the sufficient release of phosphorus in the sludge in the next step.

Although the above patent documents can eliminate the adverse effect of nitrate in the returned sludge on the anaerobic zone by pumping the concentrated sludge into the pre-anoxic zone before the concentrated sludge is returned to the anaerobic zone, the raw water directly enters the anaerobic zone, and because the sewage itself contains a certain dissolved oxygen value, the expected anaerobic condition cannot be achieved, the anaerobic effective phosphorus release of phosphorus accumulating bacteria is affected, and the phosphorus removal is not good and unstable.

Disclosure of Invention

In order to overcome the technical defects in the prior art, the invention provides a sewage nitrogen and phosphorus removal process based on an integrated biochemical reaction tank.

The technical solution adopted by the invention is as follows:

the sewage denitrification and dephosphorization process based on the integrated biochemical reaction tank comprises an anaerobic tank A, an anaerobic tank B, an anoxic tank, a mud-water separation tank, a main aeration tank and two sequencing batch tanks, wherein water continuously enters and continuously exits, and the specific flow is as follows:

after sand removal, the sewage enters an anaerobic tank A and is mixed with high-concentration denitrified sludge reflowed from an anoxic tank, dissolved oxygen in the anaerobic tank A is quickly consumed by influent organic matters, and a completely mixed solution enters an anaerobic tank B under the condition of no molecular oxygen and chemical oxygen;

phosphorus-accumulating bacteria release phosphorus in the anaerobic pool B, absorb low molecular fatty acid and store in vivo in the form of poly β hydroxybutyric acid and the like;

then the inlet mixed liquid enters a main aeration tank, the phosphorus-accumulating bacteria decompose PHB in the body to obtain energy, excessively absorb orthophosphate in the surrounding environment, and accumulate in cells in the form of polyphosphate, meanwhile, the carbonization bacteria finish the degradation of organic carbon, the nitrifying bacteria finish the nitrification of ammonia nitrogen, and the denitrification effect exists when the dissolved oxygen is low;

the two sequencing batch tanks are staggered with each other in operation, one sequencing batch tank is used as effluent of a settling zone to be discharged, and the mixed liquor of the main aeration tank enters the other sequencing batch tank to carry out anoxic and aerobic circular reaction;

and the mixed liquid after the anoxic and aerobic cyclic reaction flows back to the sludge-water separation tank, the supernatant of the sludge-water separation tank enters the main aeration tank, the precipitated thick sludge is sent to the anoxic tank, and after denitrification in the anoxic tank, the sludge is sent to the anaerobic tank A and mixed with the desanded sewage entering the anaerobic tank A to release phosphorus, and the circulation is performed in sequence.

Compared with the common traditional activated sludge process, the integrated biochemical reaction tank has the following beneficial effects:

1. the integrated biochemical reaction tank integrates the functions of water collection amount and water quality regulation, biochemical reaction and sludge precipitation, no secondary sedimentation tank needs to be additionally built, and compared with other processes, the combined structure form is adopted, so that the civil engineering investment is less;

2. the operation of the system goes through stages of anoxia, anaerobism, anoxia, aerobism, sedimentation and the like, microorganisms can be metabolized through various ways, oxygen sources in different forms are used as electron acceptors, so that organic matters are degraded more completely, energy consumption is saved, and nitrogen and phosphorus removal effects are better;

3. the sludge in the system is also subjected to anaerobic, aerobic and anoxic environments, dominant strains are screened, the growth of filamentous bacteria is inhibited, the sedimentation performance and the dehydration performance of the sludge are good, and the system is more attractive due to the lower excess sludge yield and the higher excess sludge concentration;

4. the discharged excess sludge has high concentration and small volume, and the excess sludge is convenient and simple to treat;

5. high sludge concentration, strong impact load resistance, suitability for organic wastewater treatment of various influent water qualities, and stable effluent index maintained at BOD₅Less than or equal to 10mg/L, CODcr less than or equal to 50mg/L, ammonia nitrogen less than or equal to 5mg/L, total phosphorus TP less than or equal to 0.5mg/L, total nitrogen TN less than or equal to 15mg/L, and various effluent quality indexes reach and are superior to the first-class A standard of the national emission standard.

Drawings

FIG. 1 is a flow chart of a MSBR denitrification and dephosphorization process in the prior art.

FIG. 2 is a schematic view of the process flow of the invention based on the integrated biochemical reaction tank for nitrogen and phosphorus removal of sewage.

Detailed Description

The invention will be further described with reference to the accompanying drawings in which:

as shown in fig. 2, the present embodiment provides a process for removing nitrogen and phosphorus from sewage based on an integrated biochemical reaction tank, where the integrated biochemical reaction tank includes an anaerobic tank a, an anaerobic tank B, an anoxic tank, a sludge-water separation tank, a main aeration tank, and two sequencing batch tanks, the anaerobic tank a, the anaerobic tank B, the anoxic tank, and the sludge-water separation tank are sequentially arranged side by side to form a central processing area of the integrated biochemical reaction tank, the two sequencing batch tanks are respectively disposed at two sides of the central processing area, the main aeration tank is disposed at the right sides of the central processing area and the two sequencing batch tanks, and the anaerobic tank a, the anaerobic tank B, the anoxic tank, the sludge-water separation tank, the main aeration tank, and the two sequencing batch tanks are arranged to form a rectangular structure.

Wherein: the oxygen deficiency pond, anaerobism pond A, anaerobism pond B is provided with agitating unit respectively, in the preface criticize the pond in order to prevent sludge sedimentation when the oxygen deficiency reaction, also be provided with agitating unit, pond to mud-water separation pond respectively is equipped with a wall backwash pump in two prefaces, in order to control the sludge amount of backward flow to the anaerobism pond, the oxygen deficiency pond also can be established the wall backwash pump to anaerobism pond A, establish the perforation aeration pipe in the main aeration pond, the air comes from the air-blower, preface pond water outlet is by the automatic water installation that goes out of air supply control air weir, be convenient for two prefaces to criticize and switch between the pond.

The integrated biochemical reaction tank requires that a main aeration tank and a sequence batch tank are provided with dissolved oxygen measuring instruments, the operation frequency of an aeration fan is automatically adjusted according to the DO level in the main aeration tank, especially, the blast volume is automatically adjusted when the main aeration tank and the sequence batch tank simultaneously supply oxygen and are switched into the main aeration tank to supply oxygen independently so as to save energy consumption, and the switching of the operation period and the time sequence operation of each device can be automatically controlled.

The aeration mode adopted in the main aeration tank is micropore blast aeration. Aeration is an important technical process in a sewage aerobic biological treatment system, and a blast aeration system is widely used at present, wherein purified air is provided by a blast blower and is sent into a special microporous aerator at the bottom of an aerobic tank through a pipeline system. The special microporous aerator is used for dispersing air into bubbles, diffusing the bubbles into mixed liquid, dissolving oxygen in the bubbles into the mixed liquid, providing dissolved oxygen required by microbial biochemical reaction, ensuring full mixing of sewage, enabling activated sludge to be in a suspended state, and ensuring that the activated sludge fully utilizes the dissolved oxygen in water to decompose organic pollutants and nutrients containing N/P through full contact of mud, water and gas phases, so that the aeration effect is good. The main aeration tank of the embodiment is internally provided with a microporous aerator, in particular to a tubular microporous aerator which integrates gas transmission and gas distribution, and an aeration system adopting the tubular microporous aerator does not need to lay a special horizontal gas transmission pipeline.

The continuous water feeding and water discharging process of the sewage denitrification and phosphorus removal process comprises the steps of feeding sewage after sand removal into an anaerobic tank A, mixing the sewage with high-concentration denitrification sludge flowing back from an anoxic tank, allowing dissolved oxygen in the anaerobic tank A to be quickly consumed by water feeding organic matters, feeding the mixed liquid which is completely mixed into an anaerobic tank B under the condition of no molecular oxygen and no compound oxygen, allowing phosphorus-accumulating bacteria to release phosphorus in the anaerobic tank B, absorbing low-molecular fatty acid and storing the low-molecular fatty acid in vivo in the form of poly β hydroxybutyric acid and the like, feeding the fed mixed liquid into a main aeration tank, allowing the phosphorus-accumulating bacteria to decompose PHB in the body to obtain energy, excessively absorbing orthophosphate in the surrounding environment, accumulating the orthophosphate in cells in the form of polyphosphate, allowing carbonifying bacteria to complete degradation of organic carbon, allowing nitrifying bacteria to complete nitrification of ammonia nitrogen, allowing denitrification to simultaneously exist when the dissolved oxygen is low, operating two sequential tanks in a staggered mode, feeding one sequential tank as effluent of a precipitation zone, feeding the mixed liquid into the other sequential tank to perform anoxic and aerobic sludge-water separation, feeding the sewage sludge water into the aerobic sludge-water separation tank, and feeding the anaerobic sludge-denitrification sludge-removing sludge mixed liquid into the aerobic sludge-aerobic sludge separation tank after the aerobic sludge-aerobic sludge separation tank, and the aerobic sludge-.

In the integrated biochemical reaction tank, raw sewage is mixed with high-concentration return sludge of the denitrified system, volatile short-chain fatty acid in the raw sewage is utilized, polyphosphate in microbial cells is converted and released to the surrounding environment in a phosphate form in an environment without molecular oxygen and chemical oxygen, the actual residence time of the area is prolonged due to small return flow of the anaerobic tank and high sludge concentration, the concentration of organic matter anaerobically converted into the short-chain fatty acid is increased, the phosphorus release rate is accelerated, and then the mixed liquor enters the main aeration tank together to complete the degradation and nitration process of the organic matter.

The actual total reflux of the main aeration tank is about 100 percent, can keep higher biochemical reaction reactant concentration in the main aeration tank, improve the biochemical reaction rate, the two groups of sequencing batch tanks alternately carry out circulating anoxic denitrification, aerobic stabilization and sedimentation, and are used as the sequencing batch tanks for sedimentation. The periodic switching operation and the timing sludge discharge of the system can be automatically carried out.

The raw sewage directly enters an anaerobic tank A, is mixed with return sludge in an anoxic zone to release phosphorus and then enters a main aeration tank and then enters a sequencing batch tank, if water is precipitated in a sequencing batch tank I, a mixed liquid in the sequencing batch tank firstly undergoes an anoxic reaction and then undergoes an aerobic reaction or alternatively undergoes anoxic and aerobic reactions, the mixed liquid in the anoxic and aerobic reaction stage flows back to a mud-water separation tank through a reflux pump, supernatant liquid in the mud-water separation tank enters the main aeration tank, precipitated thick sludge enters the anoxic tank to undergo denitrification and then enters the anaerobic tank to be mixed with the raw sewage, when the sequencing batch tank is subjected to the anoxic reaction, the mixed liquid in the aeration tank is continuously circulated to the sequencing batch tank, the sequencing batch tank utilizes residual carbon sources and self tissues of microorganisms to perform denitrification reaction, the aerobic reaction further degrades organic carbon sources and nitrifies ammonia nitrogen so as to stabilize the water quality, and the mixed liquid is not subjected to reflux in a pre-precipitation stage, preparing for the next half period of precipitated effluent, and discharging the residual sludge precipitated in the sequencing batch pond.

By adopting the process design, the effluent index can reach the first-class A standard GB18918-2002 discharge Standard of pollutants for municipal wastewater treatment plants, and the specific reference is shown in Table 1.

Table 1: the average value of the water quality of inlet and outlet water treated by the sewage denitrification and dephosphorization process

Index (I)	CODcr	BOD₅	TN	TP	NH3-N
						Water inflow mg/L	180	76	32	3.1	28
Water outlet mg/L	22	6.8	6.7	0.28	2.8
						Removal rate%	87.8	91.0	79.0	90.1	90.0

While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be understood by those skilled in the art that the invention is not limited by the embodiments described above, which are merely illustrative of the principles of the invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims

1. A process for removing nitrogen and phosphorus from sewage based on integrated biochemical reaction tank includes such steps as removing sand, mixing it with high-concentration denitrifying sludge, adding the mixture to anaerobic pool, releasing phosphorus from anaerobic pool, absorbing low-molecular fatty acid, storing it in the form of poly β hydroxy butyric acid, adding PHB, absorbing orthophosphate, accumulating it in the cells, decomposing it, adding polyphosphate, decomposing it, adding the phosphate, depositing it in aerobic pool, adding the mixture to aerobic pool, depositing it in aerobic pool, adding the supernatant, depositing it in aerobic pool, adding the aerobic pool, depositing it in aerobic pool, and depositing it in aerobic pool.

2. The process for removing nitrogen and phosphorus from sewage based on an integrated biochemical reaction tank as claimed in claim 1, wherein the aeration form adopted in the main aeration tank is microporous blast aeration.

3. The process of claim 1, wherein the anaerobic tank A, the anaerobic tank B, the anoxic tank and the two sequencing batch tanks are provided with stirring devices.

4. The process of claim 1, wherein a wall-through reflux pump is respectively arranged between the two sequencing batch tanks and the sludge-water separation tank and between the anoxic tank and the anaerobic tank A.