Process for partial nitritation of wastewater without seeding sludge

Abstract

The present application relates to a kind of sewage partial nitrosation method without inoculating sludge, comprising: the sewage influent containing ammonia oxidizing bacteria is carried out aeration and stirring treatment, i.e. the effluent containing nitrous nitrogen is obtained;During aeration, when the pH of sewage system is lower than the set low value, stop aeration, when the pH of sewage system is higher than the set high value, start aeration;Wherein, the set low value is 6.0-7.5, and the set high value is higher than the set low value 0.1-0.5.Compared with prior art, the present application has the advantages of not needing to inoculate sludge, simple operation, can shorten start-up time, reduce start-up cost, etc., while effectively avoiding the drawbacks of inoculating sludge method, and excellent partial nitrosation effect can be obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment, and relates to a sewage partial nitritation method without inoculation of sludge. BACKGROUND

[0002] Partial nitritation, also known as partial shortcut nitrification, is a key step of the shortcut nitrification / anaerobic ammonia oxidation process (PN / Anammox). In order to realize partial nitritation, inoculation of sludge is often needed, and the sludge is often sourced from a municipal sewage plant. The mainstream denitrification process of the municipal sewage plant is still the traditional nitrification and denitrification process. Since nitrification is complete, the sludge often contains a high content of nitrite oxidizing bacteria (NOB), and the sludge as inoculation sludge may prolong the startup time of partial nitritation. In addition, the inoculation sludge needs certain cost for taking, transporting and storing. SUMMARY

[0003] The application aims to provide a sewage partial nitritation method without inoculation of sludge, which has the advantages of not needing inoculation of sludge, simple operation, shortened startup time, reduced startup cost and the like, effectively avoids the disadvantages of the inoculation sludge method, and can obtain excellent partial nitritation effect.

[0004] The application can be realized by the following technical scheme.

[0005] A sewage partial nitritation method without inoculation of sludge comprises the following steps: performing aeration and stirring treatment on sewage influent containing ammonia-oxidizing bacteria, to obtain effluent containing nitrite nitrogen.

[0006] During the aeration process, when the pH of the sewage system is lower than a set low value, the aeration is stopped, and when the pH of the sewage system is higher than a set high value, the aeration is started; wherein the set low value is 6.0-7.5, and the set high value is 0.1-0.5 higher than the set low value.

[0007] Further, the concentration of the ammonia-oxidizing bacteria in the sewage influent is 0.0001-1 mg COD / L, and the ammonia nitrogen concentration is 20-400 mg N / L.

[0008] Further, during the aeration process, the temperature of the sewage system is not lower than 20℃, and is preferably 20-30℃.

[0009] Further, during the aeration process, the aeration amount is 1-5 L / min.

[0010] Further, the operation mode is continuous water feeding.

[0011] Further, the residence time of the sewage influent is 1-48 h.

[0012] Further, the DO of aeration is not less than 4 mg / L in the nitrosation start-up stage.

[0013] Further, the DO of aeration is not less than 4 mg / L after the nitrosation start-up.

[0014] Further, the sewage system further adds the filler, and the volume of the filler is 10-70% of the working volume of the sewage treatment tank.

[0015] Further, the filler includes polyurethane sponge square filler, high-density polyethylene wheel-shaped, sheet-shaped or spherical filler, and other material or shape fillers.

[0016] Therefore, the present application does not use the inoculation sludge method, and only enriches the AOB in the sewage by means of a certain means to realize the partial nitrosation of the sewage.

[0017] Compared with the prior art, the present application has the following characteristics:

[0018] The ammonia-oxidizing bacteria (AOB) can proliferate in the sewage in the pipeline transportation due to the reoxygenation, that is, the sewage itself contains a certain amount of AOB, and the present application is based on the feature that the sewage contains a small amount of ammonia-oxidizing bacteria, inhibits the nitrite-oxidizing bacteria by means of the intermittent aeration based on pH, and enriches the ammonia-oxidizing bacteria, thereby providing a method for realizing the partial nitrosation of the sewage without inoculation sludge, which can realize the efficient partial nitrosation in a short time, make up for the deficiency of the inoculation sludge method, save the start-up time and reduce the related cost. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The figure is the partial nitrosation realization dynamic process diagram of the partial nitrosation method of the sewage without inoculation sludge in the embodiment;

[0020] Figure 2 The figure is the pH fluctuation diagram of the partial nitrosation method of the sewage without inoculation sludge in the embodiment on the 30th day;

[0021] Figure 3 The figure is the DO dynamic process diagram of the partial nitrosation method of the sewage without inoculation sludge in the embodiment;

[0022] Figure 4 The figure is the partial nitrosation realization dynamic process diagram of the partial nitrosation method of the sewage based on inoculation sludge in the comparative example;

[0023] Figure 5 The figure is the ammonia oxidation rate and effluent nitrite nitrogen accumulation rate dynamic diagram of the partial nitrosation method of the sewage without inoculation sludge in the embodiment;

[0024] Figure 6The ammonia oxidation rate and the nitrite accumulation rate dynamic diagram of a partial nitritation method based on inoculated sludge in the comparative example. DETAILED DESCRIPTION

[0025] The application will be described in detail below with reference to the drawings and specific examples.

[0026] A partial nitritation method of sewage without inoculated sludge, comprising: using a continuous water feeding operation mode, continuously feeding sewage containing ammonia oxidizing bacteria into a sewage treatment tank, and performing aeration and stirring treatment, so as to obtain effluent containing nitrite nitrogen.

[0027] In the sewage feed, the concentration of ammonia oxidizing bacteria is 0.0001-1mg COD / L, and the ammonia nitrogen concentration is 20-400mg N / L; the residence time of the sewage feed is 1-48h.

[0028] During the aeration process, the temperature of the sewage system is not lower than 20℃, and is preferably controlled at 20-30℃; when the pH of the sewage system is lower than the set low value, the aeration is stopped, and when the pH of the sewage system is higher than the set high value, the aeration is started; preferably, the set low value is 6.0-7.5, and the set high value is 0.1-0.5 higher than the set low value; the aeration amount is 1-5L / min.

[0029] During the nitritation start-up stage, the aeration DO is not lower than 4mg / L; after the nitritation start-up, the aeration DO is controlled at 4mg / L or above.

[0030] As a preferred technical solution, fillers are also added to the sewage system, specifically including polyurethane sponge square block fillers, high-density polyethylene wheel-shaped, sheet-shaped or spherical fillers, and fillers of other materials or shapes, and the total volume addition amount is 10-70% of the working volume of the sewage treatment tank.

[0031] This example is implemented on the premise of the technical solution of the application, and gives a detailed implementation mode and specific operation process, but the protection scope of the application is not limited to the following examples.

[0032] Example:

[0033] A partial nitritation method of sewage without inoculated sludge, wherein the sewage is taken from the sewage inspection well of the library and teaching building of Tongji University, the concentration of ammonia oxidizing bacteria (AOB) is 0.0477mg COD / L, the concentration of nitritation oxidizing bacteria (NOB) is 0.00166mg COD / L, the AOB / NOB ratio is 28.7, and the ammonia nitrogen concentration is 100-300mg N / L.

[0034] The partial nitritation comprises: using a continuous water feeding operation mode, continuously feeding sewage containing ammonia oxidizing bacteria through a sewage treatment tank, and performing aeration and stirring treatment, so as to obtain effluent containing nitrite nitrogen;

[0035] In the partial nitritation, the residence time of the sewage is 12 h; during the aeration process, the temperature of the sewage system is controlled at 21-29℃; when the pH of the sewage system is lower than 6.5, the aeration is stopped, and when the pH of the sewage system is higher than 7.0, the aeration is started, the aeration amount is 3 L / min, and the DO is controlled to be not lower than 4 mg / L in the nitritation starting stage (the 8th day and before) and after that.

[0036] In other embodiments, polyurethane sponge sheet fillers are also added to the sewage system, and the total volume of the polyurethane sponge sheet fillers is 10-70% of the working volume of the sewage treatment tank.

[0037] As shown in Figure 1 The dynamic process diagram of the partial nitritation in the embodiment is shown in FIG. 2. As shown in the figure, on the 8th day, the effluent nitrite nitrogen increases to 93.3 mg N / L, and the generation of nitrate is basically not observed, and the ammonia nitrogen oxidation rate reaches 51.3%, which means that the partial nitritation is successfully started, and the starting time is at least one week earlier than the method of inoculating sludge. During the starting stage, the pH is not lower than 7.0, and after the 10th day, the pH starts to be lower than 7.0, and soon decreases to 6.5, and the intermittent aeration is automatically started by the control program. After 10 days, the pH changes between 6.5 and 7.0, and the DO value recorded every day is shown in FIG. 3. Figure 2 The aeration control program based on the pH on the 30th day is shown in FIG. 4. The DO value recorded every day is shown in FIG. 5. When in the starting aeration stage of the intermittent aeration, the DO can reach more than 8 mg / L, and when the aeration is stopped, the DO is consumed to be less than 0.5 mg / L. Figure 3

[0038] From the 10th day to the 20th day, the partial nitritation effect is stable, the ammonia nitrogen oxidation rate is 50.4%±3.8%, and the effluent nitrite nitrogen accumulation rate is 97.8%±1.0%, and the effect can reach the optimal level of the method of inoculating sludge (Table 1, Figure 5 and Figure 6 ).

[0039] Table 1. Comparison of nitritation effects of the embodiment and the comparative examples

[0040] Item Example Comparative Example Start-up completion time 8 days 14 days + 17 days Ammonia oxidation rate 50.4％±3.8％ 49.8％±0.9％ Effluent nitrite accumulation rate 97.8％±1.0％ 99.5％±0.3％

[0041] Note: *, indicating that the nitrite nitrogen accumulation rate is more than 95%, and the ammonia nitrogen oxidation rate reaches a stable range.

[0042] Comparative Example:

[0043] ​A method for partial nitrification of wastewater based on inoculated sludge, wherein the wastewater used is the same as in the example. The sludge was taken from Linping Water Treatment Plant in Hangzhou City, with an inoculation amount of 2.5 g VSS / L and an AOB / NOB ratio of 0.522.

[0044] Partial nitrification employs the commonly used pH-based aeration duration control method. The reactor operates in a sequencing batch reactor (SBR) without added packing material. The wastewater retention time is 12 hours, the sludge age is set at 10 days, and the average temperature is 25°C. Continuous aeration is performed during the SBR reaction stage at an aeration rate of 3 L / min, controlling DO ≥ 4 mg / L. Aeration and reaction are stopped when a certain pH value is reached as the endpoint, initiating subsequent sludge removal, sedimentation, and drainage stages, before entering the next SBR. Startup is divided into two phases: the first phase uses a pH setting of 6.5 for aeration duration control, and the second phase uses 7.0.

[0045] like Figure 4 As shown, when the endpoint pH for the comparative aeration duration was set at 6.5, partial nitrification could not be achieved, and nitrite nitrogen accumulated briefly in the first 3 days, but then rapidly decreased. Therefore, on the 14th day, when the endpoint pH was set at 7.0, nitrite nitrogen began to accumulate, and it took another 17 days for the nitrite nitrogen accumulation rate to reach over 95%. Figure 6 ).

[0046] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for partial nitrification of wastewater without inoculation sludge, characterized in that, The method includes: aerating and stirring the wastewater influent containing ammonia-oxidizing bacteria to obtain effluent containing nitrite nitrogen; During aeration, aeration is stopped when the pH of the wastewater system is lower than the set low value, and aeration is started when the pH of the wastewater system is higher than the set high value; wherein, the set low value is 6.0-7.5, and the set high value is 0.1-0.5 higher than the set low value; The concentration of ammonia-oxidizing bacteria in the wastewater influent is 0.0001~1 mg COD / L, and the concentration of ammonia nitrogen is 20~400 mg N / L; During the aeration process, the temperature of the wastewater system is 20-30 ℃; During the aeration process, the aeration rate is 1-5 L / min; The operating mode is continuous water intake; The retention time of the influent wastewater is 1-48 hours; During the nitrification start-up phase, the dissolved oxygen (DO) concentration in the aeration system should not be less than 4 mg / L. After nitrification is started, the dissolved oxygen (DO) concentration in the aeration system should not be less than 4 mg / L.

2. The method for partial nitrification of wastewater without inoculation sludge according to claim 1, characterized in that, The wastewater system also contains filler material, the volume of which is 10-70% of the working volume of the wastewater treatment tank.

3. The method for partial nitrification of wastewater without inoculation sludge according to claim 2, characterized in that, The fillers include polyurethane sponge block fillers, or high-density polyethylene wheel-shaped fillers, sheet-shaped fillers, or spherical fillers.

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