Method for treating inorganic high ammonia nitrogen wastewater by constructing aerobic granular sludge-biofilm dual sludge

Abstract

The present invention discloses a method for constructing an aerobic granular sludge-biofilm dual-sludge system to treat inorganic high-ammonia nitrogen wastewater. The method includes rapidly constructing an aerobic granular sludge-biofilm dual-sludge system in a SBR to treat the inorganic high-ammonia nitrogen wastewater. The aerobic granular sludge-biofilm dual-sludge system includes an inoculum of adsorption-saturated polyurethane sponge filler and mature aerobic granular sludge. This method effectively addresses the problems of slow microbial proliferation, low total nitrogen removal rate, and poor shock load resistance in inorganic high-ammonia nitrogen wastewater. It leverages the respective advantages of AGS and biofilm, achieving stable coexistence and a 1+1>2 effect. This method provides a new approach for the efficient treatment of inorganic high-ammonia nitrogen wastewater and technical support for the efficient treatment of inorganic high-ammonia nitrogen wastewater, such as ionic rare earth mine tailings.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic ammonia nitrogen wastewater treatment, and in particular relates to a method for constructing aerobic granular sludge-biofilm double sludge to treat inorganic high-ammonia nitrogen wastewater. Background Art

[0002] The moving bed biofilm reactor (MBBR) is a new and highly efficient wastewater treatment process. The aeration and water flow within the aeration tank fluidize the filler, forming a mixed system of suspended activated sludge and attached biofilm. This combined presence of attached and suspended organisms enhances the system's treatment capacity. However, when used to treat inorganic, high-ammonia nitrogen wastewater, this process suffers from low total nitrogen removal rates and poor shock load resistance, which directly impacts denitrification efficiency and sludge retention in the system.

[0003] Aerobic granular sludge (AGS) has stronger denitrification performance than traditional processes, but the denitrification performance of AGS will decrease with the decrease of the carbon-nitrogen ratio of the influent. When treating inorganic high-ammonia nitrogen wastewater, the removal of total nitrogen is very limited due to the lack of denitrification carbon source. In addition, the microorganisms in inorganic wastewater proliferate slowly and are sensitive to the environment. The endogenous metabolism of denitrifying bacteria will cause particle breakage and affect the stability of the system. Therefore, aerobic granular sludge (AGS) is currently mainly used to treat organic denitrification wastewater.

[0004] There are currently no relevant research reports on how to construct aerobic granular sludge-biofilm dual sludge in SBR to give full play to the respective advantages of AGS and biofilm to enhance the denitrification efficiency and stability of the symbiotic system. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and provide a method for treating inorganic high-ammonia nitrogen wastewater by constructing an aerobic granular sludge-biofilm dual-sludge system in an SBR, thereby avoiding AGS instability caused by biofilm proliferation and improving denitrification efficiency and stability.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for constructing an aerobic granular sludge-biofilm dual-sludge system to treat inorganic high-ammonia nitrogen wastewater is disclosed. The aerobic granular sludge-biofilm dual-sludge system is quickly constructed in an SBR to treat the inorganic high-ammonia nitrogen wastewater. The aerobic granular sludge-biofilm dual-sludge system includes inoculated adsorption saturated polyurethane sponge filler and mature aerobic granular sludge.

[0008] Furthermore, the inoculation of the saturated polyurethane sponge filler comprises: before inoculation, placing fresh polyurethane sponge filler into a high-concentration activated sludge mixed solution and aerating it continuously for more than 6 hours until the filler is saturated with adsorption.

[0009] Furthermore, the treatment object of the inoculated mature oxygen granular sludge is organic wastewater with a carbon-nitrogen ratio greater than 3, with heterotrophic bacteria as the dominant bacteria, an average particle size ≥0.3 mm, SVI30 / SVI5 ≥0.9, and the initial sludge concentration in the SBR after inoculation is ≥5000 mg / L.

[0010] Furthermore, the filling volume ratio of the adsorption-saturated polyurethane sponge filler in the SBR is 20% to 30%.

[0011] Furthermore, the SBR is a columnar reactor with a height-to-diameter ratio greater than 3, a liquid level rise greater than 4 cm after aeration, and a cycle time of 6 hours, including water inlet, aerobic reaction, anoxic reaction, aerobic reaction, sedimentation and drainage processes, wherein the sedimentation time is 1 to 5 minutes.

[0012] Furthermore, the alkalinity of the inorganic high-ammonia nitrogen wastewater is ≥8 mmol / L, and the nitrogen load is 0.8~1.2 kg / (m3·d). In the early stage of operation, an organic carbon source is added to the influent to make the influent COD the same as the COD of the organic wastewater treated by inoculation with AGS, and then the concentration of the external carbon source is gradually reduced to zero at a gradient of 100~200 mg / L per day.

[0013] Beneficial effects of the present invention:

[0014] Based on the principles of the MBBR process, this invention utilizes an AGS-biofilm dual-sludge system to increase the biomass density and biodiversity of the treatment system, thereby enhancing denitrification performance and stability. In reality, AGS and biofilms exist in both a collaborative and competitive relationship. Generally, biofilms proliferate more easily, giving them a competitive advantage over AGS in growth. To prevent excessive biofilm proliferation from destabilizing AGS, the present invention applies an adsorption treatment to the polyurethane sponge filler, ensuring that it is fully adsorbed and saturated with activated sludge before inoculation. The filler volume ratio is controlled between 20% and 30%. This approach does not affect the stability of the AGS while fully leveraging the advantages of the biofilm, such as its stability and strong degradation capacity. This invention effectively addresses the problems of slow microbial growth, low total nitrogen removal rates, and poor shock load resistance in inorganic high-ammonia nitrogen wastewater. It leverages the respective advantages of AGS and biofilms, achieving stable coexistence and a 1+1>2 effect. It offers advantages such as ease of operation and high reliability, providing a new approach for the efficient treatment of inorganic high-ammonia nitrogen wastewater and technical support for the efficient treatment of inorganic high-ammonia nitrogen wastewater, such as ionic rare earth mine tailings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram showing the sludge morphology changes in the aerobic granular sludge-biofilm dual-sludge denitrification system in Example 1 of the present invention;

[0016] Figure 2This is a diagram showing the denitrification effect of an aerobic granular sludge-biofilm dual-sludge denitrification system in treating inorganic high-ammonia nitrogen wastewater according to Example 1 of the present invention;

[0017] Figure 3 This is a diagram showing the sludge morphology changes in the aerobic granular sludge denitrification system of Comparative Example 1;

[0018] Figure 4 This is a diagram showing the denitrification effect of the aerobic granular sludge denitrification system in comparative example 1 in treating inorganic high-ammonia nitrogen wastewater;

[0019] Figure 5 This is the sludge morphology change diagram in the aerobic granular sludge + three-dimensional hollow filler system of comparative example 2;

[0020] Figure 6 This is a diagram showing the denitrification effect of the aerobic granular sludge + three-dimensional hollow filler system in treating inorganic high-ammonia nitrogen wastewater in comparative example 2;

[0021] Figure 7 This is the sludge morphology change diagram in the aerobic granular sludge + three-dimensional hollow filler + sponge filler system of comparative example 3;

[0022] Figure 8 This is a diagram showing the denitrification effect of the aerobic granular sludge + three-dimensional hollow filler + sponge filler system in comparative example 3 in treating inorganic high-ammonia nitrogen wastewater. DETAILED DESCRIPTION

[0023] The following description is completed in conjunction with the technical solutions of the embodiments of the present invention. It should be noted that the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example

[0024] The method of the present invention was applied in a small-scale SBR test to construct an AGS-biofilm double-sludge denitrification system and used to treat inorganic high-ammonia nitrogen wastewater. The specific method steps are as follows:

[0025] (1) 10 g of wastewater treatment plant excess sludge was inoculated into a 1 L beaker, and simulated organic wastewater (COD, ammonia nitrogen, and TP were 300 mg / L, 20 mg / L, and 3 mg / L, respectively) was added. Fresh polyurethane sponge fillers were added in batches and aerated for 6 hours until adsorption saturation was achieved.

[0026] (2) The SBR reactor (with an inner diameter of 8.5 cm, a height of 50 cm, and an effective volume of 2 L) was started by inoculating AGS and adsorption-saturated polyurethane sponge fillers. The volume filling ratio of the polyurethane sponge fillers was 22%, and the initial AGS concentration of the SBR was 5000 mg / L.

[0027] (3) The influent was simulated inorganic high ammonia nitrogen wastewater, and the pH of the influent was adjusted to 8.0 by sodium bicarbonate, the ammonia nitrogen was between 500 mg / L, and the nitrogen load was 1.0 kg / (m 3 ·d), alkalinity is 9~27 mmol / L, and total phosphorus is 2 mg / L.

[0028] (4) The aeration rate of the SBR is 5 L / min (liquid level rise 4 cm), and it operates for 4 cycles per day, with a cycle length of 6 hours. The operating mode is: water inlet 5 minutes, aerobic reaction 120 minutes, anoxic reaction 120 minutes, aerobic reaction 110 minutes, sedimentation 3 minutes, and drainage 2 minutes.

[0029] (5) If Figure 1 As shown in the figure, AGS was yellow, plump and smooth one day after inoculation, and the particle size and number decreased during operation. The biofilm in the polyurethane sponge filler tended to be stable after the 7th day. On the 60th day, the coexistence of AGS and biofilm was achieved, with a granulation rate of about 80%, an average particle size of about 0.8 mm, an SVI of about 50 mL / g, and a sludge concentration of about 2400 mg / L.

[0030] (6) If Figure 2 As shown in the figure, the ammonia nitrogen in the reactor's effluent is basically close to zero, the nitrite nitrogen in the effluent decreases rapidly and approaches zero, and the nitrate nitrogen accumulates significantly and contributes to the vast majority of the effluent TIN; after a sudden increase in the influent ammonia nitrogen, only a slight increase in the effluent TIN is observed in the reactor, showing good resistance to shock loads. The reactor's ammonia nitrogen removal rate is close to 100%, and the reactor's TIN removal rate is basically maintained at 50% to 60%.

[0031] Comparative Example 1 Treatment of Inorganic High Ammonia Nitrogen Wastewater by Inoculation of AGS

[0032] (1) AGS was inoculated to start the SBR reactor (inner diameter 8.5 cm, height 50 cm, effective volume 2 L). The initial AGS concentration of the SBR was 5000 mg / L.

[0033] (2) The influent was simulated inorganic high ammonia nitrogen wastewater. The pH of the influent was adjusted to 8.0 by sodium bicarbonate, the ammonia nitrogen was between 500 mg / L, and the nitrogen load was 1.0 kg / (m 3 ·d), alkalinity is 9~27 mmol / L, and total phosphorus is 2 mg / L.

[0034] (3) The aeration rate of the SBR was 5 L / min (liquid level rise 4 cm), and it operated for 4 cycles per day, with a cycle length of 6 h. The operating mode was: water inlet for 5 minutes, aerobic reaction for 120 minutes, anoxic reaction for 120 minutes, aerobic reaction for 110 minutes, sedimentation for 3 minutes, and drainage for 2 minutes.

[0035] (4) If Figure 3 As shown in the figure, AGS was yellow with plump particles and smooth surface one day after inoculation. The particle size and number decreased during operation. On the 60th day, the reactor was almost entirely filled with fine particles with an average particle size of about 0.9 mm, a granulation rate of about 88%, an SVI of about 40 mL / g, and a sludge concentration of about 3000 mg / L.

[0036] (5) If Figure 4 As shown, the reactor effluent ammonia nitrogen was essentially zero, while nitrite nitrogen decreased and then approached zero, while nitrate nitrogen accumulated significantly. After the influent ammonia nitrogen was increased within the 30th to 40th day, the effluent nitrite nitrogen, nitrate nitrogen, and TIN increased significantly. The ammonia nitrogen removal rate remained close to 100%, and the TIN removal rate gradually increased to about 60% in the first 30 days, then rapidly decreased to about 6% within the 31st to 35th day, and then rebounded to about 60%. Therefore, the reactor showed obvious inadaptability to the high nitrogen load shock, and nitrite nitrogen and nitrate nitrogen in the effluent accumulated significantly.

[0037] Comparative Example 2 Treatment of Inorganic High Ammonia Nitrogen Wastewater by Inoculation of AGS and Adsorption Saturated Three-Dimensional Hollow Fillers

[0038] (1) 10 g of wastewater treatment plant excess sludge was inoculated into a 1 L beaker, and simulated organic wastewater (COD, ammonia nitrogen, and TP were 300 mg / L, 20 mg / L, and 3 mg / L, respectively) was added. Fresh three-dimensional hollow fillers were added in batches and aerated for 6 hours until adsorption saturation;

[0039] (2) The SBR reactor (with an inner diameter of 8.5 cm, a height of 50 cm, and an effective volume of 2 L) was started by inoculating AGS and adsorption-saturated three-dimensional hollow fillers. The volume filling ratio of the three-dimensional hollow fillers was 22%, and the initial AGS concentration of the SBR was 5000 mg / L.

[0040] (3) The influent was simulated inorganic high ammonia nitrogen wastewater. The pH of the influent was adjusted to 8.0 by sodium bicarbonate, the ammonia nitrogen was between 500 mg / L, and the nitrogen load was 1.0 kg / (m 3 ·d), alkalinity is 9~27 mmol / L, and total phosphorus is 2 mg / L.

[0041] (4) The aeration rate of the SBR is 5 L / min (liquid level rise 4 cm), and it operates for 4 cycles per day, with a cycle length of 6 hours. The operating mode is: water inlet 5 minutes, aerobic reaction 120 minutes, anoxic reaction 120 minutes, aerobic reaction 110 minutes, sedimentation 3 minutes, and drainage 2 minutes.

[0042] (5) If Figure 5As shown, AGS was yellow, plump and smooth on the first day of inoculation. In the first 7 days, it was observed that the AGS in Comparative Example 1 disintegrated in large quantities and a large amount of flocculent sludge appeared. On the 60th day, the sludge concentration was about 500 mg / L, the granulation rate was about 80%, the SVI was about 42 mL / g, and the average particle size was about 0.27 mm. The three-dimensional hollow filler began to form a biofilm on the 7th day, and a layer of biofilm was basically attached to the surface of the filler on the 30th day. Thereafter, the biofilm thickness increased and appeared orange-yellow.

[0043] (6) If Figure 6 As shown in the figure, except for a sudden increase in ammonia nitrogen removal in the reactor effluent between the 30th and 40th days, it remained close to zero at other times. Both nitrate nitrogen and nitrite nitrogen in the effluent fluctuated greatly, causing the effluent TIN to also fluctuate. The ammonia nitrogen removal rate rapidly decreased to 70% between the 30th and 40th days, and remained basically at around 100% at other times. The TIN removal rate fluctuated greatly (8% to 58%). It can be seen that the three-dimensional hollow filler led to significant particle disintegration and a reduction in the amount of suspended sludge, and the water quality of the reactor effluent fluctuated greatly.

[0044] Comparative Example 3 Treatment of Inorganic High Ammonia Nitrogen Wastewater with AGS Hollow Filler + Sponge Filler

[0045] (1) 10 g of wastewater treatment plant excess sludge was inoculated into a 1 L beaker, and simulated organic wastewater (COD, ammonia nitrogen, and TP were 300 mg / L, 20 mg / L, and 3 mg / L, respectively) was added. Fresh sponge fillers and three-dimensional hollow fillers were added in batches and aerated for 6 hours until adsorption was saturated.

[0046] (2) The SBR reactor (with an inner diameter of 8.5 cm, a height of 50 cm, and an effective volume of 2 L) was started by inoculating AGS and adsorption-saturated three-dimensional hollow fillers. The volume filling ratio of the three-dimensional hollow fillers and sponge fillers was 11%, and the initial AGS concentration of the SBR was 5000 mg / L.

[0047] (3) The influent was simulated inorganic high ammonia nitrogen wastewater. The pH of the influent was adjusted to 8.0 by sodium bicarbonate, the ammonia nitrogen was between 500 mg / L, and the nitrogen load was 1.0 kg / (m 3 ·d), alkalinity is 9~27 mmol / L, and total phosphorus is 2 mg / L.

[0048] (4) The aeration rate of the SBR is 5 L / min (liquid level rise 4 cm), and it operates for 4 cycles per day, with a cycle length of 6 hours. The operating mode is: water inlet 5 minutes, aerobic reaction 120 minutes, anoxic reaction 120 minutes, aerobic reaction 110 minutes, sedimentation 3 minutes, and drainage 2 minutes.

[0049] (5) If Figure 7As shown, AGS was yellow with plump particles and smooth surface one day after inoculation. After that, a large amount of AGS disintegrated and a large amount of flocculent sludge was observed to be discharged with the effluent. At 60 days, the sludge concentration was about 600 mg / L, the granulation rate was about 75%, the SVI was about 54 mL / g, and the average particle size was about 0.32 mm. The three-dimensional hollow filler began to form biofilm on the 8th day and successfully formed biofilm around the 40th day, while the polyurethane sponge filler began to form biofilm on the 4th day and successfully completed biofilm formation on the 10th day.

[0050] (6) If Figure 8 As shown, the reactor effluent ammonia nitrogen levels remained essentially zero except for some fluctuations between the 30th and 40th days. Nitrate and nitrite nitrogen also fluctuated significantly, leading to significant fluctuations in the effluent TIN. Ammonia nitrogen removal rapidly decreased to approximately 80% between the 30th and 40th days, but remained essentially at 100% throughout the remaining time. TIN removal fluctuated between 16% and 70%. This indicates that the combination of hollow filler and sponge filler also resulted in significant particle disintegration and a reduction in suspended sludge, resulting in unstable effluent quality in terms of shock load resistance.

[0051] It can be seen from Example 1 and Comparative Examples 1 to 3 that the AGS+sponge filler system in the present invention can not only achieve the coexistence of AGS and biofilm, but also has the most stable denitrification performance. In contrast, the AGS system alone has insufficient shock load resistance. The AGS+stereoscopic hollow filler and AGS+stereoscopic hollow filler+sponge filler systems not only lead to the obvious disintegration of AGS, but also have unstable denitrification performance. The present invention can effectively solve the problems of slow microbial proliferation, low total nitrogen removal rate, and poor shock load resistance in inorganic high-ammonia nitrogen wastewater, give full play to the respective advantages of AGS and biofilm, achieve stable coexistence of the two and a 1+1>2 effect, have the advantages of simple operation and high reliability, provide a new idea for the efficient treatment of inorganic high-ammonia nitrogen wastewater, and also provide technical support for the efficient treatment of inorganic high-ammonia nitrogen wastewater such as ionic rare earth mine tailings.

[0052] The above-mentioned implementation cases are only used as technical solutions of the present invention and are for reference only. Although the present invention has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating inorganic high-ammonia nitrogen wastewater by constructing an aerobic granular sludge-biofilm dual-sludge system, characterized in that: An aerobic granular sludge-biofilm dual-sludge system is quickly constructed in an SBR to treat inorganic high-ammonia nitrogen wastewater; the aerobic granular sludge-biofilm dual-sludge system includes inoculated adsorption-saturated polyurethane sponge filler and mature aerobic granular sludge; the inoculated adsorption-saturated polyurethane sponge filler is: before inoculation, fresh polyurethane sponge filler is put into a high-concentration activated sludge mixture and aerated continuously for more than 6 hours until the filler is adsorbed and saturated, and the filling volume ratio of the adsorption-saturated polyurethane sponge filler in the SBR is 20%~30%.

2. The method for treating inorganic high-ammonia nitrogen wastewater by constructing aerobic granular sludge-biofilm dual sludge according to claim 1, characterized in that: The treatment object of inoculated mature oxygen granular sludge is organic wastewater with a carbon-nitrogen ratio greater than 3, with heterotrophic bacteria as the dominant bacteria, an average particle size ≥ 0.3 mm, SVI30 / SVI5 ≥ 0.9, and the initial sludge concentration in the SBR after inoculation ≥ 5000 mg / L.

3. The method for treating inorganic high-ammonia nitrogen wastewater by constructing aerobic granular sludge-biofilm dual sludge according to claim 1 or 2, characterized in that: SBR is a columnar reactor with a height-to-diameter ratio greater than 3. The liquid level rises more than 4 cm after aeration. The cycle time is 6 hours, including water inlet, aerobic reaction, anoxic reaction, aerobic reaction, sedimentation and drainage processes, among which the sedimentation time is 1 to 5 minutes.

4. The method for treating inorganic high-ammonia nitrogen wastewater by constructing aerobic granular sludge-biofilm dual sludge according to claim 3, characterized in that: The alkalinity of the inorganic high-ammonia nitrogen wastewater is ≥8 mmol / L, and the nitrogen load is 0.8~1.2 kg / (m3·d). In the early stage of operation, an organic carbon source is added to the influent to make the influent COD the same as the COD of the organic wastewater treated by inoculation with AGS, and then the concentration of the external carbon source is gradually reduced to zero at a gradient of 100~200 mg / L per day.

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