Load regulation type rural sewage operation method

Abstract

The invention discloses a load regulation type rural sewage operation method, relates to the technical field of sewage treatment, and aims to solve the problem that rural sewage has the characteristic of large seasonal water quality and water quantity changes, but the rural sewage generally adopts an anaerobic / anoxic / aerobic suspended activated sludge operation mode at present. According to the mode, the content, concentration and activity of the sludge cannot be maintained under the condition that the long-term inlet water quality and quantity change greatly. According to seasonal characteristics of rural sewage, an anaerobic / anoxic / aerobic activated sludge operation mode is adopted under a high-load water inlet condition, an anaerobic + micro-aerobic sludge bed operation mode is adopted under a low-load water inlet condition, and a load regulation type rural sewage operation mode is flexibly implemented according to water quality and water quantity, so that efficient treatment of the rural sewage is realized.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, in particular to a load-regulated rural sewage operation method. Background Art

[0002] The load problem of rural sewage treatment is a complex and urgent issue. Due to the high temperature in summer, residents' water consumption increases and the drainage volume increases. Due to the low temperature in winter, water consumption is relatively reduced and the drainage volume is also reduced accordingly. In addition, during the peak agricultural production period (such as spring plowing and autumn harvest), farmland runoff carries more pesticides and fertilizer residues, resulting in higher concentrations of related pollutants in sewage. Therefore, rural sewage treatment facilities may face challenges in coping with seasonal changes. High discharges and possible heavy rains in summer may cause treatment facilities to overload and affect treatment efficiency, while low temperatures and low discharges in winter may cause unstable operation of treatment facilities, requiring appropriate maintenance and management measures.

[0003] The existing rural sewage treatment process usually adopts anaerobic / anoxic / aerobic suspended activated sludge operation mode. Due to the influence of sufficient oxygen supply, the activated sludge of this operation mode has a high extracellular polymer content, a fast bacterial growth rate and high activity. However, in the low-load operation stage with low water inflow and low organic matter concentration, the equipment has problems such as poor aeration regulation, high energy consumption due to high-load operation, and difficulty in maintaining sludge activity. How to maintain sludge content, concentration and activity under low-load water inflow conditions is an urgent problem to be solved in rural sewage variable load operation. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a load-regulated rural sewage operation method.

[0005] The present invention is implemented by the following technologies: The present invention provides a load-regulated rural sewage operation method, which switches the operation mode of the microbial system in the process according to the influent load condition, and adopts the activated sludge operation mode when it is close to full load or overload state, wherein the anaerobic zone in the activated sludge operation mode is correspondingly switched to the anaerobic sludge bed in the sludge bed operation mode, the anoxic / aerobic zone corresponds to the micro-aerobic sludge bed, and the oxygen supply mode adopts the internal aeration method; Under low load conditions, i.e. when the inlet flow load is less than 50%, the sludge bed operation mode is adopted, and the oxygen supply mode of the micro-aerobic sludge bed is external aeration return oxygen supply; When the activated sludge is switched to the sludge bed operation mode, the aeration and stirring in the process are stopped, the nitrification solution is refluxed internally and the sludge is refluxed externally, and the external aeration reflux is started simultaneously. The reverse operation is performed when switching in the reverse direction. During the switching process, the dissolved oxygen in the micro-aerobic sludge bed is gradually reduced by adjusting the external aeration reflux ratio. Each stage is 5 to 10 days, and the dissolved oxygen is reduced by 0.5 mg / L in each stage until it reaches the appropriate micro-aerobic state. When switching in the reverse direction, the dissolved oxygen concentration in the aerobic zone is directly restored to 2 mg / L.

[0006] During implementation, the operation mode is changed according to the flow load of the influent. Under high-load influent conditions, the anaerobic / anoxic / aerobic suspended activated sludge operation mode is adopted; under low-load influent conditions, the anaerobic + micro-aerobic sludge bed operation mode is adopted.

[0007] Among them, in the two operating modes, the anaerobic activated sludge zone under high-load influent conditions corresponds to the anaerobic activated sludge zone under low-load influent conditions, and the anoxic / aerobic activated sludge zone under high-load influent conditions corresponds to the microaerobic sludge zone under low-load influent conditions.

[0008] The aeration method for the anaerobic / anoxic / aerobic suspended activated sludge operation mode is the internal aeration method. In the anaerobic + microaerobic sludge bed operation method, the aeration method for the microaerobic area is the external aeration return oxygen supply method, and the control range of the dissolved oxygen concentration is 0.1~0.5mg / L.

[0009] When the influent flow load is lower than 50%, the operation mode is switched, aeration and stirring in the process are stopped, nitrification solution and sludge are stopped, and external aeration and reflux oxygen supply is started to control the dissolved oxygen concentration in the micro-oxygen zone at 1.2~2mg / L, and then the dissolved oxygen in the micro-oxygen sludge bed is gradually reduced, with each stage being 5~10 days, and the dissolved oxygen is reduced by 0.5mg / L in each stage until the appropriate micro-oxygen state is reached. Finally, the control range of dissolved oxygen concentration in the micro-oxygen zone is 0.1~0.5mg / L. When switching in the reverse direction, the external aeration and reflux oxygen supply is stopped, aeration and stirring in the process are started, nitrification solution and sludge are started, and the dissolved oxygen concentration in the aerobic zone is directly restored to 2mg / L.

[0010] In the present invention, the anaerobic + micro-aerobic sludge bed operation mode, because the microorganisms in the sludge bed system adhere to the surface of the bed to form a biofilm, the sludge bed system is a static bed system, which can intercept the sludge as much as possible, has a very high biological reaction activity, can adjust its own metabolic activities according to changes in the external environment, and use suitable habitat conditions to promote the growth and activity of microorganisms. Therefore, it has the advantages of high efficiency, strong resistance to shock loads of large fluctuations in influent loads, small amount of chemical agents added, low operating costs, etc. Compared with the state of long-term high aeration volume and low load, the operation of micro-aerobic low load keeps the sludge in the endogenous respiration stage for a long time, and the self-attenuation rate is slowed down.

[0011] In summary, the seasonal variation characteristics of rural sewage are mainly manifested in seasonal discharge volume differences, seasonal water quality changes, and the relationship between seasonality and treatment efficiency. In view of the characteristics of rural sewage discharge and treatment efficiency, combined with the characteristics of the anaerobic / anoxic / aerobic operation mode of suspended activated sludge and the anaerobic + micro-aerobic sludge bed operation mode of static bed, the implementation of a new load-regulated rural sewage operation mode is of great significance to both operation and management.

[0012] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a load-regulated rural sewage operation method. When the influent load is high, the system adopts a conventional suspended activated sludge operation mode, and the sewage enters the anaerobic / anoxic / aerobic activated sludge treatment unit in sequence; in the anaerobic and anoxic tanks, the sewage is mixed with the activated sludge by a mechanical stirring device, and the aerobic tank adopts an aeration device to maintain mixing and oxygen supply. During high-load operation, the oxygen supply is sufficient, the microorganisms grow fast and have high activity, and the activated sludge system has a high content of extracellular polymers composed of organic substances such as polysaccharides, proteins and extracellular enzymes, which makes it easy to maintain a high sludge concentration, thereby resisting high-load shocks. Under low-load influent conditions, an anaerobic + micro-aerobic sludge bed operation mode is adopted to achieve sludge retention at low loads. The load-regulated rural sewage operation method of the present invention solves the problems of unstable water quality and quantity in the operation of existing rural sewage treatment facilities, low long-term load, difficulty in cultivating and taming activated sludge, inability to maintain sludge volume, and the need for repeated addition of sludge for startup. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It shows the COD operation data under the inlet water conditions of 20℃ (summer) and 13℃ (winter).

[0014] Figure 2 It shows the ammonia nitrogen operation data under the inlet water conditions of 20℃ (summer) and 13℃ (winter).

[0015] Figure 3 It shows the TN operation data under the water inlet conditions of 20℃ (summer) and 13℃ (winter).

[0016] Figure 4 It shows the TP operation data under the inlet water conditions of 20℃ (summer) and 13℃ (winter). DETAILED DESCRIPTION

[0017] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Example 1

[0018] A load-regulated rural sewage operation method, such as Figures 1 to 4 As shown, An anaerobic / anoxic / aerobic integrated device is used, and the designed influent load is 100 t / d. The aerobic pool adopts two aeration methods, namely the bottom microporous aerator and the external aeration return oxygen supply method. The influent is simulated with rural sewage in summer, and the influent load is 130% of the designed influent load. The influent COD, ammonia nitrogen, TN, and TP concentrations are 160mg / L, 30mg / L, 34mg / L, and 4.5mg / L, respectively. The total hydraulic retention time is 24h, the temperature is 20℃, the dissolved oxygen concentration in the aerobic zone is 2mg / L, the nitrification liquid return ratio is 100%, the sludge return ratio is 60%, and the aerobic zone adopts the bottom microporous aeration method. After one week of operation, the effluent COD, ammonia nitrogen, TN, and TP concentrations are 30mg / L, 0.2mg / L, 6mg / L, and 0.3mg / L, respectively.

[0019] The simulated rural sewage in winter was used as the influent, and the influent load was 40% of the designed influent load. The influent COD, ammonia nitrogen, TN, and TP concentrations were 350 mg / L, 30 mg / L, 34 mg / L, and 4.5 mg / L, respectively. The total hydraulic retention time was 24 hours, and the temperature was 13°C. The aerobic pool and the anoxic pool were supplied with oxygen by external aeration and reflux, and the dissolved oxygen concentration was 0.3 mg / L. Within a week after the influent conditions were changed, the effluent COD, ammonia nitrogen, TN, and TP concentrations were 40 mg / L, 0.8 mg / L, 11 mg / L, and 0.5 mg / L, respectively; after one month of operation, the final effluent COD, ammonia nitrogen, TN, and TP concentrations were stabilized at 26 mg / L, 0.8 mg / L, 7 mg / L, and 0.4 mg / L, respectively.

[0020] The scope of protection claimed by the present invention is not limited to the above specific embodiments. For those skilled in the art, the present invention may have various deformations and changes. Any modifications, improvements and equivalent substitutions made within the concept and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A load-regulated rural sewage operation method, Features: The operation mode of the microbial system in the process is switched according to the influent load conditions. When the system is close to full load or overloaded, the activated sludge operation mode is adopted. When the system is under low load, the sludge bed operation mode is adopted.

2. A load-regulated rural sewage operation method according to claim 1, Features: The low load state is a state where the water inlet flow load is less than 50%.

3. A load-regulated rural sewage operation method according to claim 1, Features: The anaerobic zone and the anoxic / aerobic zone in the activated sludge operation mode are respectively switched to the anaerobic sludge bed and the microaerobic sludge bed in the sludge bed operation mode.

4. A load-regulated rural sewage operation method according to claim 1, Features: The activated sludge operation mode adopts the internal aeration method, and the oxygen supply method of the micro-aerobic sludge bed under the low-load condition is external aeration reflow oxygen supply.

5. A load-regulated rural sewage operation method according to claim 1, Features: When the activated sludge is switched to the sludge bed operation mode, aeration and stirring in the process are stopped, nitrification liquid is refluxed internally and sludge is refluxed externally, and external aeration reflux is started synchronously, and reverse operation is performed during reverse switching.

6. A load-regulated rural sewage operation method according to claim 4, Features: During the switching of the activated sludge to the sludge bed operation mode, the dissolved oxygen in the microaerobic sludge bed is gradually reduced by adjusting the external aeration return ratio, with each stage lasting 5 to 10 days, and the dissolved oxygen is reduced by 0.5 mg / L in each stage until a suitable microaerobic state is reached. When switching in the reverse direction, the dissolved oxygen concentration in the aerobic zone is directly restored to 2 mg / L.

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