CN101195505A - Packing low oxygen denitrification and dephosphorization process - Google Patents

Abstract

The filling low-oxygen denitrification and phosphorus removal process relates to sewage biological treatment technology, and is used in urban and industrial sewage biological treatment processes to perform nitrogen and phosphorus removal treatment. In the process of the present invention, a filling area (21) and a low-oxygen area (22) are arranged at intervals in the aeration tank (2), and simultaneous nitrification and denitrification processes are realized in the aeration tank (2), thereby not only saving a large amount of aeration, but also It also reduces the internal reflux system and simplifies the process flow. Therefore, compared with the existing AAO series process tools in terms of operating effect and energy consumption, it can save 20% to 30% of the aeration rate, and the total reflux rate can be controlled at Within 100%, which is much lower than the total return flow of 300% to 400% of the existing AAO series process, effectively reduces the construction and operation costs of sewage treatment, and has good environmental benefits and social and economic benefits.

Description

Packing low oxygen denitrification and dephosphorization process

technical field

Filler low-oxygen denitrification and phosphorus removal process involves sewage biological treatment technology, which is applied to urban and industrial sewage biological treatment processes for nitrogen and phosphorus removal treatment.

Background technique

Biological nitrogen and phosphorus removal (AAO) series processes are widely used in urban sewage biological nitrogen and phosphorus removal sewage treatment plants due to their stable effect, mature design theory and methods, and wide adaptability. At present, the AAO series processes mainly include: traditional AAO process, improved AAO process, UCT process, VIP process, inverted AAO process, etc. The basic idea of the current AAO series process is to carry out carbon oxidation, aerobic phosphorus uptake and nitrification processes in the aerobic zone. The function of the anaerobic zone is mainly anaerobic phosphorus release, and the function of the anoxic zone is mainly denitrification; each functional zone has its own division of labor and is connected with each other through water inflow and backflow.

The existing AAO series processes have a common feature, that is, the three functional areas (anaerobic area, anoxic area, and aerobic area) required for biological nitrogen and phosphorus removal have clear water treatment functions, and the design of the functional areas is also It is to determine the parameters according to the set function, therefore, the main problems in the existing technology are:

1. The aerobic zone is defined as the three basic functions of carbon oxidation, aerobic phosphorus uptake and nitrification. Since the nitrification reaction takes the longest time, the design parameters of the aerobic zone are determined according to the nitrification requirements. However, in the design and operation of the aerobic zone, whether there is denitrification process in the aerobic zone is not considered, and the denitrification process only occurs in the anoxic zone;

2. The function of the anoxic area is defined as denitrification, and other areas are not considered in the process, such as: the denitrification in the aerobic area, resulting in a larger design capacity of the denitrification pool;

3. There are more than 2 sets of reflux systems in the existing AAO series process, and 3 sets of reflux systems in the UCT process, resulting in high process energy consumption, complicated process, and low volumetric efficiency of the reaction pool.

Contents of the invention

Facing the deficiencies of the existing AAO series of biological nitrogen and phosphorus removal processes, the inventors have a question on how to give full play to the volumetric efficiency of the three functional areas in the AAO biological nitrogen and phosphorus removal process, so that the smaller pool capacity can bear as much as possible. function, and improve process efficiency to save investment and energy consumption. Long-term research has been carried out, and it is proposed to set a filling area and a low-oxygen area in the aeration tank in the biological denitrification and phosphorus removal process to improve the volumetric efficiency of the aeration tank to achieve Save energy, reduce cost, and develop low-oxygen AAO technology with fillers that have good nitrogen and phosphorus removal effects.

The present invention is realized in the following way: the process of the present invention is composed of (lack of) anaerobic tank, aeration tank, secondary settling tank, sludge return system and aeration system. Among them, several hypoxic areas and filling areas are set at intervals in the aeration tank, and the aeration tank is connected with the aeration system. In order to realize the alternate environment of hypoxic and aerobic in the hypoxic area and the filling area, the aeration system adopts an uneven arrangement. , and according to the mathematical model, the dissolved oxygen level in the aeration tank is automatically controlled online. Control the dissolved oxygen (DO) in the filler area to be in an aerobic state, and the DO value is controlled at 1.5-2.5mg/L. In this environment, a large number of nitrifying bacteria can be enriched in the biofilm on the filler surface, which greatly improves aeration The density of nitrifying bacteria in the filling area in the pool strengthens the removal effect of the filling area on ammonia nitrogen. When the sewage passes through the filling area, ammonia nitrogen will be quickly oxidized into nitrate nitrogen by the nitrifying bacteria in the biofilm. The dissolved oxygen (DO) in the hypoxic zone is controlled by the DO online automatic control system, and the DO value is controlled at 0.3-0.8mg/L. Within this DO range, the carbon oxidation process and nitrification function can continue, while the aeration The denitrification process in the pool will also be greatly enhanced, showing the effect of simultaneous nitrification and denitrification. A large amount of nitrate nitrogen produced in the filling area enters the hypoxic area and is denitrified into nitrogen by the denitrifying bacteria in the activated sludge, thereby completing the denitrification treatment. In this way, the concentration of nitrate nitrogen in the effluent of the aeration tank is much lower than that of the effluent of the aeration tank in the traditional AAO series process, so that the return system in the process can be completely eliminated, so it is only necessary to keep the sludge return system for proper sludge return .

Before the process of the present invention treats urban sewage or industrial sewage, the sewage needs to be pretreated by grids, degreasing, etc. or depending on the water quality, and then pretreated by the short-time primary sedimentation tank in front of the process of the present invention, and then enter the present invention. process, the effluent treated by the process of the present invention can obtain good denitrification and phosphorus removal effects, and the energy consumption and investment cost of the process operation of the present invention are lower than the existing traditional AAO series processes.

Features and advantages of the present invention are:

1. Filling in the aeration tank can enrich a large number of nitrifying bacteria, thereby increasing the concentration of nitrifying bacteria in the filling area and significantly improving the volumetric efficiency of the aeration tank. After the volumetric efficiency of the aeration tank is improved, space can be saved to set up multiple low-oxygen zones, and the original three functions of carbon oxidation, aerobic phosphorus uptake and nitrification can still be guaranteed, thus saving a lot of aeration compared with the traditional process. Gas, process energy saving is very obvious;

2. The arrangement density of aeration heads in the aeration tank is set and controlled according to the different oxygen demands of each filling area and hypoxic area, and the aeration is automatically controlled according to the preset dissolved oxygen level of each functional area in the aeration tank , to achieve the purpose of maximally saving aeration energy consumption and precise control;

3. In the aeration tank, the filling area and the low-oxygen area are arranged alternately to realize the effect of biofilm nitrification in the filling area and the synchronous nitrification and denitrification of activated sludge in the low-oxygen area, so that the nitrate nitrogen produced by nitrification is basically in the aeration tank. Most of them can be removed in the hypoxic zone, thus canceling the reflux system in the mixed liquid used for denitrification;

4. Since the concentration of nitrate nitrogen at the outlet of the aeration tank is very low, the nitrate nitrogen carried in the return sludge is also very low, thus ensuring good anaerobic phosphorus release conditions in the anaerobic tank of the process and strengthening the phosphorus removal effect of the process;

5. Simultaneous nitrification and denitrification in the aeration tank makes most of the non-aeration area of the process become an anaerobic area, while the anoxic area is very small, thus strengthening the effect of anaerobic hydrolysis, which is beneficial to granular and colloidal organic matter hydrolytic acidification, so the process of the present invention can adopt the method of canceling primary sedimentation tank or short-term primary sedimentation tank, saving process cost;

6. The process of the present invention realizes simultaneous nitrification and denitrification processes in the aeration tank, thereby not only saving a large amount of aeration, but also reducing the internal backflow system and simplifying the process flow. Therefore, compared with the existing AAO series process tools in terms of operating effect and operating energy consumption, the aeration rate can be saved by 20% to 30%.

7. Since the process of the present invention has only one set of sludge return system, its total return flow rate is lower than 100%, which is much lower than the total return flow rate of 300% to 400% of the existing AAO series process, effectively reducing the construction and operation of sewage treatment The cost, and the aeration system of the aeration tank uses a mathematical model to automatically control the dissolved oxygen level set in the filling area and the hypoxic area, which effectively guarantees the effect of water treatment.

Description of drawings

Accompanying drawing is process principle of the present invention and flow chart schematic diagram, wherein:

Fig. 1. is the schematic diagram of process principle of the present invention;

As shown in the figure, (lack of) anaerobic tank 1, aeration tank 2, filling area 21, hypoxic area 22, secondary settling tank 3, sludge return system 4, and aeration system 5.

Detailed ways

The present invention is further described with reference to the above-mentioned accompanying drawings.

The process of the present invention consists of a (deficiency) anaerobic tank 1, an aeration tank 2, a secondary sedimentation tank 3, a sludge return system 4 and an aeration system 5. An agitation device is arranged in the (deficiency) anaerobic tank 1 , and a filler area 21 and a low-oxygen area 22 are arranged at intervals in the aeration tank 2 , and the aeration tank 2 communicates with the aeration system 5 . The aeration system 5 controls the dissolved oxygen levels set in the filling area 21 and the hypoxic area 22 through automatic control to ensure the effect of water treatment.

1. Treatment of urban sewage

Before the urban sewage enters the process of the present invention, the sewage is firstly pretreated by grids and degreasing, and then pretreated by the short-time primary sedimentation tank in front of the process of the present invention according to the water quality. The pretreated sewage enters the process (deficiency) anaerobic pool 1 of the present invention, and the sludge brought back by the sewage and sludge return system 4 in the pool is fully stirred and mixed by the stirring device, so that the microorganisms in the remaining sludge are in the pool. Fully react with the organic matter in the sewage. Since the return sludge contains a small amount of nitrate nitrogen, the proportion of the anoxic section in the (deficiency) anaerobic tank 1 is very small, and it is basically an anaerobic zone. Phosphorus accumulating bacteria absorb a large amount of VFA in the pool, and perform anaerobic phosphorus release to accumulate the power for subsequent phosphorus uptake. Due to the small proportion of the anoxic section and the increased anaerobic capacity, the granular and colloidal organic matter in the sewage can be effectively hydrolyzed and acidified, and the difficulty of subsequent sewage treatment is reduced.

(Deficiency) When the effluent mixture from the anaerobic tank 1 enters the aeration tank 2, the sewage first enters the packing area 21, where the organic matter undergoing anaerobic hydrolysis is activated by the active sewage under the aerobic condition with a DO value of 2.5 mg/L. Nitrifying bacteria enriched in the biofilm begin to carry out aerobic nitrification of ammonia nitrogen and produce nitrate. After being treated in the packing area 21, the mixed liquid enters the hypoxic area 22, and the dissolved oxygen in the hypoxic area 22 is controlled at 0.3 mg/L by the dissolved oxygen automatic control system. In this dissolved oxygen state, the oxidation and nitrification functions of organic matter remain It can continue, because there are a large number of anoxic areas inside the sludge flocs, so that there is an obvious denitrification effect in this area. A large amount of nitrate nitrogen formed in the filling area 21 is converted into nitrogen gas by the denitrifying bacteria in the activated sludge in the low oxygen area 22 to complete denitrification. The residual organic matter, ammonia nitrogen and nitrate nitrogen in the sewage are further removed in the subsequent alternate treatment of the filling area 21 and the hypoxic area 22. The phosphorus in the sewage is also absorbed and removed by the phosphorus accumulating bacteria in the aeration tank, and the effluent reaches the discharge level. Standard rear discharge. A small amount of nitrate nitrogen at the outlet of the aeration tank can be completely removed by increasing the sludge return flow in an appropriate amount. The total return flow will be controlled within 100%, and the remaining sludge will be discharged after being treated in the secondary sedimentation tank 3, and the phosphorus will also be discharged. It is removed during the sludge removal process.

2. Treatment of industrial sewage

Enter the process (lack of) anaerobic pool 1 of the present invention through the industrial sewage of pretreatment, in the sludge that sewage and sludge return system 4 bring back in the pool fully agitate mixing process in stirring device, the microorganism in the return sludge and The organic matter in the sewage fully reacts, releases anaerobic phosphorus and accumulates the power for subsequent phosphorus absorption, and the granular and colloidal organic matter in the sewage is effectively hydrolyzed and acidified. The effluent mixed liquid treated by the (deficiency) anaerobic tank 1 enters the aeration tank 2, and the mixed liquid first enters the packing area 21, where the organic matter undergoing anaerobic hydrolysis is under aerobic conditions with a DO value of 1.5 mg/L. Oxygenated and degraded by activated sludge and biofilm, aerobic nitrification of ammonia nitrogen is carried out, and the mixed solution after treatment in the filler area 21 enters the hypoxic area 22, and the dissolved oxygen in the hypoxic area 22 is controlled at 0.8mg/L by the automatic control system , in this dissolved oxygen state, the oxidation and nitrification functions of organic matter can still continue, and a large amount of nitrate nitrogen formed in the filling area 21 is converted into nitrogen by the denitrifying bacteria in the activated sludge in the low oxygen area 22, Complete the denitrification process. The residual organic matter, ammonia nitrogen and nitrate nitrogen in the sewage are further removed in the subsequent alternate treatment of the filling area 21 and the hypoxic area 22. The phosphorus in the sewage is also absorbed and removed by the phosphorus accumulating bacteria in the aeration tank, and the effluent reaches the discharge level. Standard rear discharge. A small amount of nitrate nitrogen at the outlet of the aeration tank will be completely removed by increasing the sludge return flow in an appropriate amount, the total return flow will be controlled within 100%, and the remaining sludge will be discharged after being treated in the secondary sedimentation tank 3. It is removed during the sludge removal process.

Claims (2)

1. filling material hypoxia removing nitric dephosphorization technique, by (lacking) anaerobic pond (1), aeration tank (2), second pond (3), mud return-flow system (4) and aerating system (5) are formed, it is characterized in that: in (lacking) anaerobic pond (1), whipping appts is set, packing area (21) and hypoxemia district (22) are set in aeration tank (2) at interval; Enter (lacking) anaerobic pond (1) through pretreated sewage, the mud that sewage and mud return-flow system (4) are taken back in the pond fully stirs combination treatment by whipping appts, carry out alternate treatment through packing area (21) and hypoxemia district (22) that water mixed liquid enters in the aeration tank (2) that go out that (lacking) anaerobic pond (1) is handled, the water outlet of aeration tank (2) is discharged after second pond (3) processing is up to standard.

2. according to the described denitrification dephosphorization technique of claim, it is characterized in that: technology is when operation, and the packing area has been in oxygen condition in (21), and dissolved oxygen (DO) value is controlled at 1.5～2.5mg/L, and the dissolved oxygen value in hypoxemia district (22) is controlled at 0.3～0.8mg/L.

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