Method for enhancing biological phosphorus removal by using aerobic starvation

Abstract

The invention relates to the technical field of sewage treatment, in particular to a method for enhancing biological phosphorus removal through aerobic starvation. Inoculating the activated sludge-wastewater mixture subjected to anaerobic and aerobic treatment into an aerobic environment, and carrying out aerobic starvation treatment to obtain an activated sludge-wastewater mixture subjected to aerobic starvation treatment; sequentially carrying out anaerobic treatment and aerobic treatment on the activated sludge-wastewater mixture subjected to aerobic starvation treatment to obtain biological phosphorus removal wastewater. According to the method, the content of other strains is reduced through aerobic starvation treatment, so that the abundance of the fermentation type phosphorus-accumulating bacteria is increased, the phosphorus removal capacity of the fermentation type phosphorus-accumulating bacteria is improved, the enhanced activated sludge has higher phosphorus removal and sludge reduction performance in sewage treatment, and the method can be effectively popularized and applied.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular, to a method for enhancing biological phosphorus removal by aerobic starvation. Background Art

[0002] With the increasing discharge of wastewater, the treatment difficulty has increased, and the challenges of treating wastewater have also been continuously increasing. Excessive phosphorus in water bodies can cause eutrophication. As a relatively low-cost, mature and effective phosphorus removal technology, biological phosphorus removal processes have been widely used in various countries. Therefore, sewage treatment plants often utilize the metabolic ability of microorganisms in activated sludge to purify wastewater. Due to the fluctuations in wastewater flow and composition, bacteria will experience aerobic starvation, and problems such as unstable phosphorus removal efficiency and low removal rate often occur.

[0003] Different from traditional polyphosphate-accumulating organisms, fermentative polyphosphate-accumulating organisms have been identified as the main polyphosphate-accumulating organisms in wastewater. They have the ability of fermentative metabolism, can maintain cell survival or promote proliferation through fermentation, can ferment and convert organic compounds such as amino acids into small molecules such as volatile fatty acids, reduce the dependence on exogenous volatile fatty acids and improve the phosphorus removal efficiency. The substances produced by their fermentation can be metabolized and utilized by themselves and other organisms, and they can also store amino acids in the anaerobic stage and consume them in the aerobic stage to optimize the phosphorus removal performance. Therefore, studying how to enhance the biological phosphorus removal system dominated by fermentative polyphosphate-accumulating organisms by aerobic starvation is of great significance for improving wastewater treatment performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for enhancing biological phosphorus removal by aerobic starvation.

[0005] The technical solution of the present invention for solving the above technical problems is as follows: The present invention provides a method for enhancing biological phosphorus removal by aerobic starvation, comprising the following steps: S1. Inoculate the activated sludge containing fermentative polyphosphate-accumulating organisms into an anaerobic environment, and then add the wastewater to be treated for anaerobic treatment to obtain an anaerobic-treated activated sludge-wastewater mixture; in the activated sludge, the initial abundance of fermentative polyphosphate-accumulating organisms is 3.5%-5%; S2. Transfer the anaerobic-treated activated sludge-wastewater mixture to an aerobic environment for aerobic treatment to obtain an aerobic-treated activated sludge-wastewater mixture; S3. Inoculate the aerobic-treated activated sludge-wastewater mixture into an aerobic environment for aerobic starvation treatment to obtain an aerobic-starvation-treated activated sludge-wastewater mixture; S4. Subject the aerobic-starvation-treated activated sludge-wastewater mixture to anaerobic treatment and aerobic treatment in sequence to obtain the wastewater with biological phosphorus removal.

[0006] On the basis of the above technical solutions, the present invention can also be improved as follows.

[0007] Further, in step S3, in the aerobic environment, the concentration of activated sludge is 6000 - 7000 mg / L.

[0008] Further, the dissolved oxygen content in the aerobic environment is greater than or equal to 6 mg / L.

[0009] Further, during the aerobic starvation treatment, no nutrients enter the aerobic environment.

[0010] Further, the time of the aerobic starvation treatment is 9.5 - 10.5 days.

[0011] Further, after the aerobic starvation treatment is completed, the abundance of the fermentative polyphosphate-accumulating organisms in the activated sludge is 65% - 78%.

[0012] Further, in step S1, the concentration of PO4 3- -P in the wastewater to be treated is 4 - 8 mg / L, and the concentration of chemical oxygen demand COD is 190 - 210 mg / L.

[0013] Further, in step S1, the time of the anaerobic treatment is 180 - 300 min, and the temperature is 19 - 21 °C.

[0014] Further, in step S2, the reaction time of the aerobic treatment is 120 - 200 min, and the temperature is 19 - 21 °C.

[0015] Further, the steps of the anaerobic treatment in step S4 are the same as those of the anaerobic treatment in step S1, and the steps of the aerobic treatment in step S4 are the same as those of the aerobic treatment in step S1.

[0016] The beneficial effects of the present invention are as follows: (1) In the method for aerobic starvation-enhanced biological phosphorus removal of the present invention, through the aerobic starvation treatment, the content of other strains is reduced, and the abundance of fermentative polyphosphate-accumulating organisms is increased; (2) In the method for aerobic starvation-enhanced biological phosphorus removal of the present invention, the phosphorus removal ability of fermentative polyphosphate-accumulating organisms is improved, so that the enhanced activated sludge has stronger phosphorus removal and sludge reduction performance in sewage treatment; (3) In the method for aerobic starvation-enhanced biological phosphorus removal of the present invention, the specific conditions of the aerobic starvation treatment are defined, so that the enhancement effect reaches the best; (4) The method for aerobic starvation-enhanced biological phosphorus removal of the present invention breaks through the concept in the prior art that aerobic starvation has a destructive effect on the sewage treatment system, and realizes the enhancement of the biological phosphorus removal method and system through appropriate aerobic starvation treatment, and can be effectively promoted and applied. Description of the Drawings

[0017] Figure 1 The figure is a flowchart of the method for enhancing biological phosphorus removal by aerobic starvation of the present invention. Detailed Description of the Invention

[0018] The principles and features of the present invention will be described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0019] As Figure 1 shown, the method for enhancing biological phosphorus removal by aerobic starvation of the present invention includes the following steps: S1. Inoculate the activated sludge containing fermentative polyphosphate-accumulating organisms into an anaerobic environment, and then add the wastewater to be treated for anaerobic treatment to obtain an activated sludge-wastewater mixture after anaerobic treatment; in the activated sludge, the initial abundance of fermentative polyphosphate-accumulating organisms is 3.5%-5%; S2. Transfer the activated sludge-wastewater mixture after anaerobic treatment to an aerobic environment for aerobic treatment to obtain an activated sludge-wastewater mixture after aerobic treatment; S3. Inoculate the activated sludge-wastewater mixture after aerobic treatment into an aerobic environment for aerobic starvation treatment to obtain an activated sludge-wastewater mixture after aerobic starvation treatment; S4. Subject the activated sludge-wastewater mixture after aerobic starvation treatment to anaerobic treatment and aerobic treatment in sequence to obtain wastewater with biological phosphorus removal.

[0020] Compared with other functional bacteria in sewage treatment, fermentative polyphosphate-accumulating organisms do not rely on nutrients in the influent and can use surplus sludge as a growth substrate. Therefore, they have a stronger resistance to aerobic starvation conditions. The method for enhancing biological phosphorus removal by aerobic starvation of the present invention increases the abundance of fermentative polyphosphate-accumulating organisms through aerobic starvation treatment, improving the nutrient removal effect and sludge reduction performance in sewage treatment.

[0021] The method for enhancing biological phosphorus removal by aerobic starvation of the present invention breaks through the concept in the prior art that aerobic starvation has a destructive effect on the sewage treatment system, and strengthens the biological phosphorus removal method and system through appropriate aerobic starvation treatment.

[0022] The method of the present invention is particularly suitable for activated sludge with a relatively high initial abundance of fermentative polyphosphate-accumulating organisms. For an initial abundance of 3.5%-5%, whether anaerobic starvation or anoxic starvation is used, the effects of increasing abundance, improving nutrient removal, and enhancing sludge reduction are all lower than those of aerobic starvation.

[0023] Preferably, in step S3, in the aerobic environment, the concentration of the activated sludge is 6000-7000 mg / L.

[0024] Preferably, in the aerobic environment, an air pump is used for aeration to provide oxygen, so that the dissolved oxygen content in the aerobic environment is greater than or equal to 6 mg / L; by providing oxygen through aeration, the oxygen content in the aerobic environment is ensured, and at the same time, the dissolved oxygen content is maintained at a high concentration, enabling fermentative polyphosphate-accumulating organisms to be in a complete aerobic environment and ensuring sufficient aerobic conditions during the aerobic starvation treatment process.

[0025] Preferably, during the aerobic starvation treatment, no nutrients enter the aerobic environment; in this way, it can be ensured that fermentative polyphosphate-accumulating organisms are completely unable to obtain additional nutrients and completely use the excess sludge as the growth substrate, thereby effectively strengthening the biological phosphorus removal system.

[0026] Preferably, the time for the aerobic starvation treatment is 9.5 - 10.5 days; this time can ensure the sufficiency of aerobic starvation and prevent problems such as low abundance of fermentative polyphosphate-accumulating organisms and poor strengthening effect due to insufficient treatment time.

[0027] Preferably, after the aerobic starvation treatment is completed, the abundance of fermentative polyphosphate-accumulating organisms in the activated sludge is 65% - 78%; the fermentative polyphosphate-accumulating organisms with this abundance can effectively treat the wastewater.

[0028] In the method of the present invention, before aerobic starvation, the activated sludge and the wastewater are first subjected to anaerobic-aerobic treatment, which can passivate the activated sludge and effectively proliferate the fermentative polyphosphate-accumulating organisms therein, facilitating further strengthening in the subsequent process.

[0029] Preferably, in step S1, the concentration of PO4 3- -P in the wastewater to be treated is 4 - 8 mg / L, and the concentration of chemical oxygen demand COD is 190 - 210 mg / L; among them, PO4 3- -P is provided by KH2PO4, and the chemical oxygen demand COD is provided by peptone.

[0030] Preferably, in step S1, the time for anaerobic treatment is 180 - 300 min, and the temperature is 19 - 21°C.

[0031] Preferably, in step S2, the reaction time for aerobic treatment is 120 - 200 min, and the temperature is 19 - 21°C.

[0032] In the method of the present invention, after aerobic starvation, the activated sludge and the wastewater are again subjected to anaerobic-aerobic treatment to restore the activated sludge and the wastewater, enabling the fermentative polyphosphate-accumulating organisms with high abundance to effectively treat the phosphorus in the wastewater and achieve biological phosphorus removal.

[0033] Preferably, the anaerobic treatment steps in step S4 are the same as those in step S1, and the aerobic treatment steps in step S4 are the same as those in step S1.

[0034] The method of the present invention aims to strengthen the biological phosphorus removal system dominated by fermentative polyphosphate-accumulating organisms under aerobic starvation conditions, thereby improving the performance of the biological phosphorus removal system, reducing sludge production, and providing a new method for stable phosphorus removal in wastewater treatment plants.

[0035] The present invention is described below through specific examples and comparative examples: Example 1 The activated sludge in this example is from the Beijing Gaobeidian Wastewater Treatment Plant. The specific steps of this example are as follows: (1) Inoculate the activated sludge containing fermentative polyphosphate-accumulating organisms into the anaerobic section of the reaction tank, and treat the wastewater for 240 min. The wastewater contains 6 mg / L of PO4 3- -P (provided by KH2PO4) and 190 mg / L of chemical oxygen demand COD (provided by peptone), to obtain the activated sludge and sewage after anaerobic treatment. The initial abundance of fermentative polyphosphate-accumulating organisms is 3.5%.

[0036] (2) Drain the activated sludge and wastewater after anaerobic treatment into the aerobic section of the reaction tank, and react for 180 min at a temperature of 19°C to obtain the activated sludge containing fermentative polyphosphate-accumulating organisms after aerobic treatment.

[0037] (3) Subject the obtained activated sludge containing fermentative polyphosphate-accumulating organisms to aerobic starvation. The sludge concentration is 6400 mg / L, and no nutrients are provided during starvation. The air pump operates to ensure sufficient aeration, and the starvation lasts for 9.5 d.

[0038] (4) Inoculate the activated sludge and wastewater after aerobic starvation into the anaerobic section of the reaction tank. Other operations are the same as the previous anaerobic treatment and aerobic treatment to carry out the recovery of activated sludge and complete biological phosphorus removal.

[0039] After the recovery of activated sludge is completed, the treated wastewater is detected.

[0040] After detection, after wastewater treatment, the phosphorus removal rate of the effluent reaches 85%, the removal rate of chemical oxygen demand (COD) is 78%, the daily sludge reduction rate is 71.4% compared with that before aerobic starvation, MLVSS / MLSS is 63%, and the final abundance of fermentative polyphosphate-accumulating organisms is 66.43%.

[0041] Example 2 The activated sludge in this example is from the Beijing Gaobeidian Wastewater Treatment Plant. The specific steps of this example are as follows: (1) Inoculate the activated sludge containing fermentative polyphosphate-accumulating organisms into the anaerobic section of the reaction tank, and treat the wastewater for 240 min. The wastewater contains 6 mg / L of PO4 3- -P (provided by KH2PO4) and 190 mg / L of chemical oxygen demand COD (provided by peptone), to obtain the activated sludge and wastewater after anaerobic treatment. The initial abundance of fermentative polyphosphate-accumulating organisms is 5%.

[0042] (2) Drain the activated sludge and wastewater after anaerobic treatment into the aerobic section of the reaction tank, and react for 180 min at a temperature of 20 °C to obtain the activated sludge containing fermentative polyphosphate-accumulating organisms after aerobic treatment.

[0043] (3) Aerobically starve the obtained activated sludge containing fermentative polyphosphate-accumulating organisms. The sludge concentration is 6400 mg / L, and no nutrients are provided during starvation. The air pump operates to ensure sufficient aeration, and starve for 10 d.

[0044] (4) Inoculate the activated sludge after aerobic starvation into the anaerobic section of the reaction tank, and the other operations are the same as the previous anaerobic treatment and aerobic treatment to carry out the recovery of activated sludge and complete biological phosphorus removal.

[0045] After the recovery of activated sludge is completed, the treated wastewater is detected.

[0046] After detection, after wastewater treatment, the phosphorus removal rate of the effluent reaches 96%, the removal rate of chemical oxygen demand (COD) is 80%, the daily sludge reduction rate is 72.8% compared with that before aerobic starvation, MLVSS / MLSS is 56%, and the final abundance of fermentative polyphosphate-accumulating organisms is 75.26%.

[0047] Example 3 The activated sludge in this example comes from Beijing Gaobeidian Wastewater Treatment Plant. The specific steps of this example are as follows: (1) Inoculate the activated sludge containing fermentative polyphosphate-accumulating organisms into the anaerobic section of the reaction tank, and treat the wastewater for 240 min. The wastewater contains 6 mg / L of PO4 3- -P (provided by KH2PO4) and 190 mg / L of chemical oxygen demand COD (provided by peptone), to obtain the activated sludge and wastewater after anaerobic treatment. The initial abundance of fermentative polyphosphate-accumulating organisms is 4.5%.

[0048] (2) Drain the activated sludge and wastewater after anaerobic treatment into the aerobic section of the reaction tank, and react for 180 min at a temperature of 21 °C to obtain the activated sludge containing fermentative polyphosphate-accumulating organisms after aerobic treatment.

[0049] (3) Aerobically starve the activated sludge containing fermentative polyphosphate-accumulating organisms obtained above. The sludge concentration is 6400 mg / L, and no nutrients are provided during starvation. The air pump operates to ensure sufficient aeration, and starvation lasts for 10.5 d.

[0050] (4) Inoculate the activated sludge after aerobic starvation into the anaerobic section of the reaction tank. Other operations are the same as those of the aforementioned anaerobic treatment and aerobic treatment to recover the activated sludge and complete biological phosphorus removal.

[0051] After the recovery of the activated sludge, the treated wastewater is detected.

[0052] After detection, after wastewater treatment, the phosphorus removal rate of the effluent reaches 88%, the removal rate of chemical oxygen demand (COD) is 78%, the daily sludge reduction rate compared with that before aerobic starvation is 71.8%, MLVSS / MLSS is 60%, and the final abundance of fermentative polyphosphate-accumulating organisms is 66.33%.

[0053] Comparative Example 1 The difference between this comparative example and Example 2 is that the aerobic starvation time lasts for 1 d, and other steps are the same.

[0054] After detection, after wastewater treatment, the phosphorus removal rate of the effluent reaches 64%, the removal rate of chemical oxygen demand (COD) is 56%, the daily sludge reduction rate compared with that before aerobic starvation is 4.46%, MLVSS / MLSS is 75%, and the final abundance of fermentative polyphosphate-accumulating organisms is 18.7%.

[0055] Comparative Example 2 The difference between this comparative example and Example 2 is that the aerobic starvation lasts for 5 d, and other steps are the same.

[0056] After detection, after wastewater treatment, the phosphorus removal rate of the effluent reaches 73%, the removal rate of chemical oxygen demand (COD) is 58%, the daily sludge reduction rate compared with that before aerobic starvation is 42.6%, MLVSS / MLSS is 68%, and the final abundance of fermentative polyphosphate-accumulating organisms is 36.5%.

[0057] Comparative Example 3 The difference between this comparative example and Example 2 is that the aerobic starvation lasts for 15 d, and other steps are the same.

[0058] After detection, after wastewater treatment, the phosphorus removal rate of the effluent reaches 69%, the removal rate of chemical oxygen demand (COD) is 57.3%, the daily sludge reduction rate compared with that before aerobic starvation is 31.7%, MLVSS / MLSS is 70%, and the final abundance of fermentative polyphosphate-accumulating organisms is 35.2%.

[0059] Comparative Example 4 The difference between this comparative example and Example 2 is that the initial abundance of fermentative polyphosphate-accumulating organisms is 2%, and other steps are the same.

[0060] After detection, after wastewater treatment, the phosphorus removal rate of the effluent reaches 70%, the chemical oxygen demand (COD) removal rate is 57%, the daily sludge reduction rate compared with before aerobic starvation is 30%, the MLVSS / MLSS is 68.2%, and the final abundance of fermentative polyphosphate-accumulating organisms is 35%.

[0061] Comparative Example 5 The difference between this comparative example and Example 2 is that the initial abundance of fermentative polyphosphate-accumulating organisms is 8%, and other steps are the same.

[0062] After detection, after wastewater treatment, the phosphorus removal rate of the effluent reaches 75%, the chemical oxygen demand (COD) removal rate is 69%, the daily sludge reduction rate compared with before aerobic starvation is 52%, the MLVSS / MLSS is 66%, and the final abundance of fermentative polyphosphate-accumulating organisms is 48%.

[0063] The treatment parameters and results of the above examples and comparative examples are shown in Table 1: Table 1 It can be seen from the above experimental results that when the aerobic starvation treatment time is too short or too long, the abundance of fermentative polyphosphate-accumulating organisms is not high. Specifically, since the activated sludge and wastewater have just undergone aerobic treatment before aerobic starvation, when the starvation time is too short, the nutrients in the activated sludge are not completely consumed by each strain, so there are still a certain amount of other strains in the activated sludge, resulting in a lower abundance of fermentative polyphosphate-accumulating organisms. When the starvation time is too long, the fermentative polyphosphate-accumulating organisms themselves will also be damaged, leading to a decrease in their abundance in the activated sludge.

[0064] For example, the aerobic starvation time of Comparative Example 2 is 5 days, and the final abundance of its fermentative polyphosphate-accumulating organisms is only 36.5%, and its daily sludge reduction rate is only 42.6%, indicating that the sludge treatment effect of this comparative example is poor.

[0065] It can be seen from a comparison of Comparative Examples 4 and 5 with Example 2 that when the initial abundance of fermentative polyphosphate-accumulating organisms is too high or too low, the effect is poor.

[0066] It can be seen from the experimental results of the above examples and comparative examples that the method of the present invention can effectively strengthen the biological phosphorus removal system dominated by fermentative polyphosphate-accumulating organisms through aerobic starvation conditions, realize the improvement of biological phosphorus removal ability and reduce sludge production.

[0067] In the description of the present invention, it should be noted that the descriptions with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples.

[0068] The foregoing are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for enhancing biological phosphorus removal by aerobic starvation, characterized in that, It includes the following steps: S1. Inoculate the activated sludge containing fermentative polyphosphate-accumulating organisms into an anaerobic environment, and then add the wastewater to be treated for anaerobic treatment to obtain an activated sludge-wastewater mixture after anaerobic treatment; in the activated sludge, the initial abundance of fermentative polyphosphate-accumulating organisms is 3.5%-5%; S2. Transfer the activated sludge-wastewater mixture after anaerobic treatment to an aerobic environment for aerobic treatment to obtain an activated sludge-wastewater mixture after aerobic treatment; S3. Inoculate the activated sludge-wastewater mixture after aerobic treatment into an aerobic environment for aerobic starvation treatment to obtain an activated sludge-wastewater mixture after aerobic starvation treatment; In the aerobic environment, the concentration of the activated sludge is 6000-7000 mg / L; the dissolved oxygen content in the aerobic environment is greater than or equal to 6 mg / L; during the aerobic starvation treatment, no nutrients enter the aerobic environment; the time of the aerobic starvation treatment is 9.5-10.5 days; S4. Subject the activated sludge-wastewater mixture after aerobic starvation treatment to anaerobic treatment and aerobic treatment in sequence to obtain wastewater with biological phosphorus removal.

2. The method for enhancing biological phosphorus removal by aerobic starvation according to claim 1, characterized in that, After the aerobic starvation treatment is completed, the abundance of the fermentative polyphosphate-accumulating organisms in the activated sludge is 65%-78%.

3. A method for enhancing biological phosphorus removal by aerobic starvation according to claim 1 or 2, characterized in that, In step S1, the concentration of PO4 3- -P in the wastewater to be treated is 4 - 8 mg / L, and the concentration of chemical oxygen demand COD is 190 - 210 mg / L.

4. A method for enhancing biological phosphorus removal by aerobic starvation according to claim 3, characterized in that, In step S1, the time of the anaerobic treatment is 180-300 min, and the temperature is 19-21 °C.

5. A method for enhancing biological phosphorus removal by aerobic starvation according to claim 1 or 2, characterized in that, In step S2, the reaction time of the aerobic treatment is 120-200 min, and the temperature is 19-21 °C.

6. A method for enhancing biological phosphorus removal by aerobic starvation according to claim 1 or 2, characterized in that, The steps of the anaerobic treatment in step S4 are the same as those of the anaerobic treatment in step S1, and the steps of the aerobic treatment in step S4 are the same as those of the aerobic treatment in step S1.

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