Municipal sewage short-range denitrification anaerobic ammonia oxidation filter tank and sewage treatment method

Abstract

The invention provides a town sewage short-range denitrification anaerobic ammonia oxidation filter tank and a sewage treatment method. The town sewage short-range denitrification anaerobic ammonia oxidation filter tank comprises a mixing area, a biological filter layer area and a settling area. The biological filter layer area is filled with modified composite filler, and bioactive florae such as anaerobic ammonia oxidizing bacteria, short-cut denitrifying bacteria and acetic bacteria are attached to the surface of the biological filter layer area. According to the filter, a short-cut denitrification anaerobic ammonia oxidation filter deep denitrification technical system is constructed, so that the energy consumption and the carbon source demand are reduced. The treatment method comprises the steps of pretreatment, uniform mixing, biological reaction filtration, precipitation and the like, jet flow is used for assisting uniform mixing during uniform mixing, specific dissolved oxygen concentration, pH value, temperature and carbon-nitrogen ratio are controlled in the reaction filtration process, and a micro electric field can also be used for assisting. And the settling zone is periodically backwashed. The filter tank is small in size and low in energy consumption, external carbon sources can be greatly reduced, effluent reaches the discharge standard, an excellent denitrification effect is achieved, and a filter tank flora regulation and control method, a denitrification performance dynamic regulation and control method and a quick filter tank starting strategy are provided.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly relates to a short-cut denitrification anaerobic ammonium oxidation filter for urban sewage and a sewage treatment method. Background Art

[0002] With the increasing awareness of environmental protection, the development of sewage treatment technology has become the focus of global attention. Especially in the construction process of Hainan Free Trade Port, an excellent ecological environment has become an indispensable important support. In recent years, Hainan Province has achieved remarkable results in improving the water environment quality. However, the urban sewage treatment field still faces a series of severe challenges, which seriously restrict the in-depth promotion of water pollution prevention and control work.

[0003] At present, the traditional denitrification filter process is generally used for urban sewage treatment. However, this process has exposed many deficiencies in practical applications. On the one hand, the traditional denitrification filter process has high energy consumption and requires a large amount of energy to maintain its normal operation during the operation process, which not only increases the operating cost but also does not conform to the current concept of green and low-carbon development. On the other hand, due to the problem of insufficient carbon source, when the traditional process treats sewage, the total nitrogen in the effluent is difficult to reach the discharge standard, resulting in an increased risk of water eutrophication and posing a potential threat to the ecological environment. At the same time, in the traditional denitrification filter process, it is difficult to effectively regulate the cultivation of biofilms and the structure of microbial flora. It is difficult to quickly start the anaerobic ammonium oxidation flora, and the dominant flora such as short-cut denitrifying bacteria and anaerobic ammonium oxidation bacteria cannot occupy the dominant position in the biofilm, and the high efficiency of short-cut denitrification anaerobic ammonium oxidation synergistic denitrification cannot be fully exerted, making the overall sewage treatment effect difficult to reach the ideal state.

[0004] In view of the serious deficiencies of the traditional sewage treatment process in terms of energy consumption, carbon source demand, denitrification efficiency, and flora regulation, it is imperative to develop a new sewage treatment technology. Summary of the Invention

[0005] In view of this, the present invention proposes a short-cut denitrification anaerobic ammonium oxidation filter for urban sewage and a sewage treatment method

[0006] The technical solution of the present invention is realized as follows: A short-cut denitrification anaerobic ammonium oxidation filter for urban sewage includes a mixing zone, a biological filter layer zone, and a sedimentation zone. The biological filter layer zone is filled with biological fillers. The biological fillers are composite fillers that have been modified. The surface of the composite fillers is attached with biological active flora, and the thickness of the filter layer is 1-3 meters.

[0007] Further, the composite fillers are ceramic particles, carbon nanotubes, and titanium dioxide nanoparticles with a mass ratio of (3.5-5.5):(1.2-3.0):(0.2-0.8).

[0008] Further, the modification method of the composite filler is specifically to mix ceramic particles, carbon nanotubes and titanium dioxide nanoparticles, slowly pour them into acetone to submerge the composite filler, with the mass-volume ratio of the composite filler to acetone being 1:5-10 g / mL, then perform ultrasonic treatment with an ultrasonic power of 200-500 W and an ultrasonic time of 30-60 min. After that, dry at 40-60 °C for 1-3 h, grind, with a particle size of 3-5 mm, a specific surface area greater than 1000 m 2 / g, and a porosity of 40-50%.

[0009] Further, the bioactive flora are anaerobic ammonium oxidation bacteria, short-cut denitrifying bacteria and acetic acid bacteria, with a viable bacteria count greater than 1×10 6 cfu / ml.

[0010] Further, the mass ratio of the anaerobic ammonium oxidation bacteria, short-cut denitrifying bacteria and acetic acid bacteria is 50-70:20-40:10-20.

[0011] Further, a method for treating urban sewage, which is to introduce urban sewage into an anaerobic ammonium oxidation filter to construct a short-cut denitrifying anaerobic ammonium oxidation filter for deep nitrogen removal, includes the following steps:

[0012] S1. Pretreatment: First, the urban sewage is pretreated to remove large particulate suspensions and floating matters therein;

[0013] S2. Mixing: The pretreated sewage and the raw domestic sewage enter the mixing zone in the anaerobic ammonium oxidation filter through the inlet pipe, and the sewage is mixed by jet flow, with a water inflow of 10-13 L / h;

[0014] S3. Biological reaction filtration: The water after mixing enters the biological filter layer zone and undergoes reaction filtration under the action of the bioactive flora. Control the hydraulic retention time to be 4-6 hours, and the inlet and outlet water velocities are both 0.5-1 m / h; ensure that the sewage is in full contact with the microorganisms on the filter media;

[0015] S4. Sedimentation: The water after reaction filtration enters the sedimentation zone for sedimentation, and the treated water is discharged from the outlet. At the same time, the sedimentation zone is regularly backwashed using the backwash water outlet.

[0016] Further, the jet flow rate in step S2 is 10-30% of the total water volume in the mixing zone, the jet pressure is maintained at 0.2-0.5 MPa, the jet time interval is 5-15 minutes, and the jet time for each time is 3-5 minutes.

[0017] Further, during the reaction filtration in step S3, control the dissolved oxygen concentration to be 0.1-0.5 mg / L, the pH value to be 7.5-8.5, the temperature to be 30-35 °C, and the carbon-nitrogen ratio to be 1-3.

[0018] Further, during the reaction filtration process in step S3, a micro-electric field is also used for assistance. The electric field strength is controlled at 0.5 - 3 V / cm, and the intermittent power-on mode is adopted. The ratio of the power-on time to the power-off time is set to (1 - 3):(2 - 4).

[0019] Further, in the precipitation area of step S4, the influent water velocity is controlled at 0.1 - 0.3 m / s, so that the particles have enough time to precipitate to the bottom of the pool under the action of gravity.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The short-cut denitrification anaerobic ammonium oxidation filter and treatment method for urban sewage of the present invention have significant advantages compared with the prior art. Through the innovative filter structure, including a mixing area, a biological filter layer area, and a precipitation area, the filter layer is filled with modified composite fillers and biological active flora to construct a short-cut denitrification anaerobic ammonium oxidation filter deep nitrogen removal system, synergistically achieving deep nitrogen removal, reducing the total nitrogen content to meet the effluent standards; combining with the tropical climate in Hainan to optimize the microbial growth conditions, reducing additional energy consumption, reducing the dependence on external carbon sources through the raw water ratio of carbon to nitrogen and microbial action, reducing costs and environmental risks; precisely controlling reaction conditions such as dissolved oxygen, pH value, temperature, and carbon to nitrogen ratio, and cooperating with micro-electric field assistance to enhance the microbial activity and pollutant removal ability, improving the treatment efficiency and stability; jet mixing the sewage and reasonably controlling the parameters to ensure uniform mixing, controlling the influent water velocity in the precipitation area and performing regular backwashing to ensure the precipitation effect and extend the service life, improving the overall operation performance; the high-performance composite fillers provide attachment sites, improve the mass transfer efficiency, are anti-pollution, and have a long service life, and the synergistic effect of the dominant flora enhances the system adaptability and anti-shock ability to ensure long-term stable operation. Description of the Drawings

[0022] Figure 1 is an anaerobic ammonium oxidation filter;

[0023] In the figure, 1 is the mixing area; 2 is the biological filter layer area; 3 is the precipitation area. Detailed Embodiments

[0024] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0025] The experimental methods used in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0026] The materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial channels unless otherwise specified.

[0027] Example 1

[0028] 1. Filter construction

[0029] Construct an anaerobic ammonium oxidation filter, with the mixing zone, biological filter layer zone, and sedimentation zone connected in sequence. The mixing zone is used to mix and fully blend the effluent from the front-end equipment and the raw domestic sewage.

[0030] The biological filter layer zone is filled with biological fillers. The biological fillers are composite fillers that have undergone modification treatment. The surface of the composite fillers is attached with biological active flora. The thickness of the filter layer is 1 meter, which filters the incoming water and fully reacts with the flora.

[0031] The sedimentation zone is externally connected to the water outlet and backwash water outlet, and is used to precipitate the treated water and conduct backwashing regularly.

[0032] 2. Filler modification and flora attachment

[0033] The composite filler is composed of ceramic particles, carbon nanotubes, and titanium dioxide nanoparticles with a mass ratio of 3.5:1.2:0.2. The specific modification method of the composite filler is to mix the ceramic particles, carbon nanotubes, and titanium dioxide nanoparticles, slowly pour acetone, immerse the composite filler, and the mass-volume ratio of the composite filler to acetone is 1:5 g / mL. Then, ultrasonic treatment is carried out. The ultrasonic power is 200 W, and the ultrasonic time is 30 min. After that, it is dried at 40 °C for 1 h, ground, and the particle size is 3 mm. The specific surface area is greater than 1000 m 2 / g, the porosity is 40%. The biological active flora are anaerobic ammonium oxidation bacteria, short-cut denitrifying bacteria, and acetic acid bacteria. The anaerobic ammonium oxidation bacteria, short-cut denitrifying bacteria, and acetic acid bacteria are attached to the composite filler according to the mass ratio of 50:40:10, so that the viable bacteria count is greater than 1×10 6 cfu / ml.

[0034] 3. Sewage treatment method

[0035] S1. Pretreatment: The urban sewage is first pretreated to remove the large particle suspended solids and floating objects in it.

[0036] S2. Mixing: The sewage from the front-end equipment and the raw domestic sewage enter the mixing zone of the anaerobic ammonium oxidation filter through the inlet pipe, and the sewage is mixed by jetting. The jet flow rate is 10% of the total water volume in the mixing zone, the jet pressure is maintained at 0.2 MPa, the jet time interval is 5 minutes, and the jet time for each time is 3 minutes. The water inflow rate is 10 L / h.

[0037] S3, biological reaction filtration: after the mixing, the water enters the biological filter layer area, and is subjected to reaction filtration under the action of biologically active bacteria. The hydraulic retention time is controlled to be 4 hours. During the reaction filtration process, the dissolved oxygen concentration is controlled to be 0.1 mg / L, the pH value is 7.5, the temperature is 30°C, and the carbon-nitrogen ratio is 1. During the reaction filtration process, a micro-electric field is used to assist, and the electric field strength is controlled to be 0.5 V / cm. An intermittent power-on mode is used, and the ratio of the power-on time to the power-off time is set to 1:2. The water inlet speed and the water outlet speed are both 0.5 m / h to ensure that the sewage is fully in contact with the microorganisms on the filter material.

[0038] S4. Sedimentation: The water that has passed the reaction filtration enters the sedimentation area for sedimentation. The water inlet speed is 0.1m / s. The treated water is discharged from the outlet. At the same time, the sedimentation area is backwashed regularly using the backwash water outlet.

[0039] Example 2

[0040] 1. Filter construction

[0041] Construct an anaerobic ammonium oxidation filter tank, where the mixing zone, biological filter layer zone and sedimentation zone are connected in sequence. The mixing zone is used to mix and fully mix the effluent from the front-end equipment and the raw domestic sewage water;

[0042] The biological filter layer is filled with biological fillers, which are modified composite fillers with biologically active bacteria attached to the surface of the composite fillers. The thickness of the filter layer is 3 meters, which filters the incoming water and fully reacts with the bacteria.

[0043] The sedimentation area is connected to an external water outlet and a backwash outlet, which are used to sediment the treated water and perform backwashing regularly.

[0044] 3. Filler modification and bacterial attachment

[0045] The composite filler is ceramic particles, carbon nanotubes and titanium dioxide nanoparticles in a mass ratio of 5.5:3.0:0.8. The modification method of the composite filler is specifically to mix the ceramic particles, carbon nanotubes and titanium dioxide nanoparticles, slowly pour acetone, immerse the composite filler, the mass volume ratio of the composite filler to acetone is 1:10 g / mL, and then perform ultrasonic treatment, the ultrasonic power is 500W, the ultrasonic time is 60min, and then dry at 60°C for 3h, grind, and the particle size is 5mm, and the specific surface area is greater than 1000m 2 / g, porosity 50%, biologically active bacteria are anaerobic ammonium oxidizing bacteria, short-range denitrifying bacteria and acetic acid bacteria, anaerobic ammonium oxidizing bacteria, short-range denitrifying bacteria and acetic acid bacteria are attached to the composite filler in a mass ratio of 70:20:10, so that the number of live bacteria is greater than 1×10 6 cfu / ml.

[0046] 3. Wastewater treatment methods

[0047] S1. Pretreatment: The urban sewage is pretreated to remove large suspended solids and floating matter;

[0048] S2, mixing: the pretreated sewage enters the mixing zone in the anaerobic ammonium oxidation filter from the water inlet pipe, and the sewage is mixed by jetting, the jet flow rate is 30% of the total water volume in the mixing zone, the jet pressure is maintained at 0.5MPa, the jet time interval is 15 minutes, each jet time is 5 minutes, and the water inlet is 13L / h;

[0049] S3, biological reaction filtration: after the mixing, the water enters the biological filter layer area, and is subjected to reaction filtration under the action of biologically active bacteria. The hydraulic retention time is controlled to be 6 hours. During the reaction filtration process, the dissolved oxygen concentration is controlled to be 0.5 mg / L, the pH value is 8.5, the temperature is 35°C, and the carbon-nitrogen ratio is 3. During the reaction filtration process, a micro-electric field is used to assist, and the electric field strength is controlled to be 3V / cm. Intermittent power-on mode is adopted, and the ratio of power-on time to power-off time is set to 3:4. The water inlet speed and water outlet speed are both 1m / h to ensure that the sewage is fully in contact with the microorganisms on the filter material;

[0050] S4. Sedimentation: The water that has passed the reaction filtration enters the sedimentation area for sedimentation. The water inlet speed is 0.3m / s. The treated water is discharged from the outlet. At the same time, the sedimentation area is backwashed regularly using the backwash water outlet.

[0051] Example 3

[0052] 1. Filter construction

[0053] Construct an anaerobic ammonium oxidation filter tank, where the mixing zone, biological filter layer zone and sedimentation zone are connected in sequence. The mixing zone is used to mix and fully mix the effluent from the front-end equipment and the raw domestic sewage water;

[0054] The biological filter layer is filled with biological fillers, which are modified composite fillers with biologically active bacteria attached to the surface of the composite fillers. The thickness of the filter layer is 2 meters, which filters the incoming water and fully reacts with the bacteria.

[0055] The sedimentation area is connected to an external water outlet and a backwash outlet, which are used to sediment the treated water and perform backwashing regularly.

[0056] 2. Filler modification and bacterial attachment

[0057] The composite filler is ceramic particles, carbon nanotubes and titanium dioxide nanoparticles in a mass ratio of 4.5:2.5:0.6. The modification method of the composite filler is specifically to mix the ceramic particles, carbon nanotubes and titanium dioxide nanoparticles, slowly pour acetone, immerse the composite filler, the mass volume ratio of the composite filler to acetone is 1:8 g / mL, and then perform ultrasonic treatment, the ultrasonic power is 300W, the ultrasonic time is 50min, and then dry at 50°C for 2h, grind, and the particle size is 4mm, and the specific surface area is greater than 1000m2 / g, with a porosity of 45%. The bioactive bacterial community consists of anaerobic ammonium oxidation bacteria, short-cut denitrifying bacteria, and acetic acid bacteria. The anaerobic ammonium oxidation bacteria, short-cut denitrifying bacteria, and acetic acid bacteria are attached to the composite filler in a mass ratio of 60:30:10, such that the viable bacterial count is greater than 1×10 6 cfu / ml.

[0058] 3. Sewage treatment method

[0059] S1. Pretreatment: The municipal sewage is first pretreated to remove large particulate suspensions and floating matters therein.

[0060] S2. Mixing: The pretreated sewage enters the mixing zone in the anaerobic ammonium oxidation filter tank from the inlet pipe, and the sewage is mixed by jetting. The jet flow rate is 20% of the total water volume in the mixing zone, the jet pressure is maintained at 0.4 MPa, the jet time interval is 10 minutes, the jet time for each time is 4 minutes, and the influent flow rate is 12 L / h.

[0061] S3. Biological reaction filtration: The water after mixing enters the biological filter layer zone and undergoes reaction filtration under the action of the bioactive bacterial community. The hydraulic retention time is controlled at 5 hours. During the reaction filtration process, the dissolved oxygen concentration is controlled at 0.3 mg / L, the pH value is 8.0, the temperature is 33°C, and the carbon-nitrogen ratio is 2. Microelectric field assistance is also used during the reaction filtration process. The electric field strength is controlled at 2.0 V / cm, and the intermittent power-on method is adopted. The ratio of the power-on time to the power-off time is set to 2:3. The influent speed and the effluent speed are both 0.8 m / h to ensure sufficient contact between the sewage and the microorganisms on the filter media.

[0062] S4. Sedimentation: The water after reaction filtration enters the sedimentation zone for sedimentation. The influent speed is 0.2 m / s, and the treated water is discharged from the outlet. At the same time, the sedimentation zone is regularly backwashed using the backwash water outlet.

[0063] Comparative example 1: Without using the modified composite filler

[0064] 1. Filter tank construction

[0065] The composite filler is not modified, and the others are the same as in Example 3.

[0066] 2. Filler modification and bacterial attachment

[0067] The composite filler is ceramic particles, carbon nanotubes, and titanium dioxide nanoparticles with a mass ratio of 4.5:2.5:0.6. The bioactive bacterial community consists of anaerobic ammonium oxidation bacteria, short-cut denitrifying bacteria, and acetic acid bacteria. The anaerobic ammonium oxidation bacteria, short-cut denitrifying bacteria, and acetic acid bacteria are attached to the composite filler in a mass ratio of 60:30:10, such that the viable bacterial count is greater than 1×10 6 cfu / ml.

[0068] 3. Sewage treatment method

[0069] S1, Pretreatment: The municipal sewage is first pretreated to remove large particulate suspensions and floating matters therein.

[0070] S2, Mixing: The pretreated sewage enters the mixing zone in the anaerobic ammonium oxidation filter through the inlet pipe, and the sewage is mixed by jetting. The jet flow rate is 20% of the total water volume in the mixing zone, the jet pressure is maintained at 0.4 MPa, the jet time interval is 10 minutes, the jet time for each time is 4 minutes, and the water inflow rate is 12 L / h.

[0071] S3, Biological reaction filtration: The water after mixing enters the biological filter layer zone and undergoes reaction filtration under the action of the biological active flora. The hydraulic retention time is controlled at 5 hours. During the reaction filtration process, the dissolved oxygen concentration is controlled at 0.3 mg / L, the pH value is 8.0, the temperature is 33 °C, and the carbon-nitrogen ratio is 2. During the reaction filtration process, a micro-electric field is also used for assistance, the electric field strength is controlled at 2.0 V / cm, and the intermittent power-on method is adopted. The ratio of the power-on time to the power-off time is set to 2:3. The water inflow rate and the water outflow rate are both 0.8 m / h to ensure sufficient contact between the sewage and the microorganisms on the filter media.

[0072] S4, Sedimentation: The water after reaction filtration enters the sedimentation zone for sedimentation. The water inflow rate is 0.2 m / s, and the treated water is discharged from the outlet. At the same time, the sedimentation zone is periodically backwashed using the backwash water outlet.

[0073] Comparative Example 2: Without jetting operation

[0074] 1. Filter construction

[0075] Same as Example 3.

[0076] 2. Packing modification and flora attachment

[0077] Same as Example 3.

[0078] 3. Sewage treatment method

[0079] S1, Pretreatment: The municipal sewage is first pretreated to remove large particulate suspensions and floating matters therein.

[0080] S2, Mixing: The pretreated sewage enters the mixing zone in the anaerobic ammonium oxidation filter through the inlet pipe, the water inflow rate is 12 L / h, and there is no jetting operation.

[0081] S3. Biological reaction filtration: The water after mixing enters the biological filter layer area and undergoes reaction filtration under the action of the biological active flora. The hydraulic retention time is controlled at 5 hours. During the reaction filtration process, the dissolved oxygen concentration is controlled at 0.3 mg / L, the pH value is 8.0, the temperature is 33 °C, and the carbon-nitrogen ratio is 2. Microelectric field assistance is also used during the reaction filtration process. The electric field intensity is controlled at 2.0 V / cm, and the intermittent power-on method is adopted. The ratio of the power-on time to the power-off time is set at 2:3. The inlet and outlet water velocities are both 0.8 m / h to ensure sufficient contact between the sewage and the microorganisms on the filter media.

[0082] S4. Sedimentation: The water after reaction filtration enters the sedimentation area for sedimentation. The inlet water velocity is 0.2 m / s, and the treated water is discharged from the outlet. At the same time, the sedimentation area is regularly backwashed using the backwash water outlet.

[0083] Comparative Example 3: Without attached short-range denitrifying bacteria and acetic acid bacteria

[0084] 1. Filter construction

[0085] Same as Example 3.

[0086] 2. Packing modification and flora attachment

[0087] The composite packing is ceramic particles, carbon nanotubes, and titanium dioxide nanoparticles with a mass ratio of 4.5:2.5:0.6. The specific method for modifying the composite packing is to mix the ceramic particles, carbon nanotubes, and titanium dioxide nanoparticles, slowly pour acetone, immerse the composite packing, and the mass-volume ratio of the composite packing to acetone is 1:8 g / mL. Then, ultrasonic treatment is carried out. The ultrasonic power is 300 W, and the ultrasonic time is 50 min. After that, it is dried at 50 °C for 2 h and ground. The particle size is 4 mm, the specific surface area is greater than 1000 m 2 / g, the porosity is 45%, and the biological active flora is only anaerobic ammonium oxidation bacteria, which are attached to the composite packing to make the viable bacteria count greater than 1×10 6 cfu / ml.

[0088] 3. Sewage treatment method

[0089] S1. Pretreatment: The urban sewage is first pretreated to remove the large particle suspended solids and floating objects in it.

[0090] S2. Mixing: The pretreated sewage enters the mixing area in the anaerobic ammonium oxidation filter through the inlet pipe, and the sewage is mixed by jetting. The jet flow rate is 20% of the total water volume in the mixing area, the jet pressure is maintained at 0.4 MPa, the jet time interval is 10 minutes, and the jet time for each time is 4 minutes. The water inflow rate is 12 L / h.

[0091] S3. Biological reaction filtration: The water after mixing enters the biological filter layer area and undergoes reaction filtration under the action of the biological active flora. The hydraulic retention time is controlled at 5 hours. During the reaction filtration process, the dissolved oxygen concentration is controlled at 0.3 mg / L, the pH value is 8.0, the temperature is 33 °C, and the carbon-nitrogen ratio is 2. Microelectric field assistance is also used during the reaction filtration process. The electric field strength is controlled at 2.0 V / cm, and the intermittent power-on method is adopted. The ratio of the power-on time to the power-off time is set at 2:3. The inlet and outlet water velocities are both 0.8 m / h to ensure sufficient contact between the sewage and the microorganisms on the filter media.

[0092] S4. Sedimentation: The water that has undergone reaction filtration enters the sedimentation area for sedimentation. The inlet water velocity is 0.2 m / s, and the treated water is discharged from the outlet. At the same time, the sedimentation area is regularly backwashed using the backwash water outlet.

[0093] Comparative Example 4: Without using microelectric field assistance

[0094] 1. Filter construction: The same as in the example, using modified composite fillers, and the inoculation of biological active flora is the same as in Example 3.

[0095] 2. Sewage treatment method: In the biological reaction filtration step (S3 in Example 3), except without using microelectric field assistance, other operating conditions such as the inlet water velocity, hydraulic retention time, dissolved oxygen, pH value, temperature, carbon-nitrogen ratio, etc. are the same as in the example. The subsequent steps such as sedimentation are also the same as in Example 3.

[0096] I. Water quality index detection

[0097] 1. Ammonia nitrogen (NH4 + -N) removal rate: Take the water sample, add potassium sodium tartrate solution to mask interfering ions, and then add Nessler's reagent. Ammonia nitrogen reacts with Nessler's reagent to form a light red-brown complex. At a wavelength of 420 nm, measure the absorbance with a spectrophotometer, and obtain the ammonia nitrogen concentration in the water sample by comparing with the standard curve.

[0098] Ammonia nitrogen removal rate (%) = [(inlet ammonia nitrogen concentration - outlet ammonia nitrogen concentration) / inlet ammonia nitrogen concentration] × 100%

[0099] 2. Total nitrogen (TN) removal rate: Using the alkaline potassium persulfate digestion ultraviolet spectrophotometry method. Under the condition of alkaline medium at 120 - 124 °C, use potassium persulfate as the oxidant to convert the nitrogen element in the nitrogen-containing compounds in the water sample into nitrate. Measure the absorbance of the digested water sample at wavelengths of 220 nm and 275 nm, and calculate the total nitrogen content according to the formula (corrected absorbance A = A 220 - 2A 275 , and the total nitrogen content is proportional to the corrected absorbance).

[0100] Total nitrogen removal rate (%) = [(Total nitrogen concentration in influent - Total nitrogen concentration in effluent) / Total nitrogen concentration in influent] × 100%.

[0101] 3. COD removal rate: Measured by the potassium dichromate method. Add potassium dichromate solution to the water sample. In a strong acidic medium, with silver sulfate as a catalyst, after boiling and refluxing, use ferroin as an indicator and titrate the un-reduced potassium dichromate in the water sample with ammonium ferrous sulfate. Calculate the mass concentration of oxygen consumed according to the amount of ammonium ferrous sulfate used, which is the COD value.

[0102] COD removal rate (%) = [(COD concentration in influent - COD concentration in effluent) / COD concentration in influent] × 100%

[0103] 4. Turbidity of the effluent after sedimentation: Tested by a turbidimeter.

[0104] 5. Result data

[0105] Table 1:

[0106]

[0107] From the above results, it can be seen that the experimental group shows obvious advantages in aspects such as ammonia nitrogen removal rate, total nitrogen removal rate, COD removal rate, and turbidity removal. This indicates that the treatment conditions adopted in the examples can more effectively treat sewage and achieve better treatment effects.

[0108] Compared with Comparative Example 1, the selection of a mixture of ceramics, carbon nanotubes, and titanium dioxide nanoparticles for modification results in a rough and porous surface, providing a large number of attachment sites for microorganisms, facilitating the growth of anaerobic ammonium oxidation bacteria and short-cut denitrifying bacteria, etc., forming an ordered microbial community structure, improving the absorption and conversion efficiency of anaerobic ammonium oxidation bacteria for ammonia nitrogen, accelerating the conversion of ammonia nitrogen to nitrogen gas, promoting the step-by-step conversion of nitrogen, and increasing the total nitrogen removal rate; carbon nanotubes increase conductivity to promote electron transfer, enhance the ability of microorganisms to degrade organic matter, enabling the composite filler to adsorb some organic matter, reducing the organic matter concentration in sewage, reducing the metabolic burden of microorganisms, facilitating further degradation, and increasing the COD removal rate. And the modified composite filler of the present invention can intercept suspended particles in sewage, aggregate fine suspended particles to form flocs for sedimentation, and reduce the turbidity of sewage.

[0109] Compared with Comparative Example 2, using a jet in the mixing zone generates a strong entrainment effect in water, entraining the surrounding water into the jet, thereby achieving the mixing of sewage, ensuring full contact between sewage and microorganisms, ensuring uniform distribution of ammonia nitrogen, providing sufficient substrates for anaerobic ammonium oxidation bacteria, extending the contact time, promoting ammonia nitrogen conversion, and increasing the removal rate; it can enhance the mass transfer between sewage and microorganisms, accelerate the nitrogen conversion reaction, improve the total nitrogen removal effect. At the same time, it causes suspended particles to collide and rub, destabilizes the colloid, promotes the aggregation of particles into larger flocs, facilitates sedimentation, and reduces turbidity.

[0110] Compared with Comparative Example 3, in terms of ammonia nitrogen removal rate, anaerobic ammonium oxidation bacteria, as the core bacterial community, directly convert ammonia nitrogen into nitrogen gas. The high removal rate in the examples benefits from their efficient metabolism. Short-cut denitrifying bacteria convert nitrate nitrogen into nitrite nitrogen, providing substrates for anaerobic ammonium oxidation bacteria to promote ammonia nitrogen removal. Acetic acid bacteria regulate the carbon-nitrogen ratio by producing acid, indirectly enhancing the activity of anaerobic ammonium oxidation bacteria. For the total nitrogen removal rate, anaerobic ammonium oxidation bacteria directly participate in the key reaction, short-cut denitrifying bacteria participate in the conversion of nitrate nitrogen, and acetic acid bacteria maintain a stable carbon source supply and carbon-nitrogen ratio to ensure the activity of both. In terms of COD removal rate, the metabolism of anaerobic ammonium oxidation bacteria can decompose some organic matter, short-cut denitrifying bacteria consume organic matter when using the carbon source, and acetic acid bacteria produce acid to promote the decomposition of organic matter and provide a carbon source. In terms of turbidity reduction, the efficient metabolism of anaerobic ammonium oxidation bacteria reduces the suspension of pollutants, short-cut denitrifying bacteria assist in avoiding the accumulation of nitrogen pollutants, and acetic acid bacteria stabilize the environment to promote the decomposition of pollutants by the bacterial community, helping to remove impurities in the sedimentation area. Overall, the synergistic effect of the three makes the examples superior to some of the comparative examples in terms of ammonia nitrogen, total nitrogen, COD removal rates and turbidity control, showing good sewage treatment effects.

[0111] Compared with Comparative Example 4, the use of a microelectric field assistance during the reaction filtration process can promote the metabolic activities of the anaerobic ammonium oxidation bacterial community, enhance the ability of microorganisms to transfer electrons, thereby increasing the reaction rate. The specific microelectric field of the present invention can stimulate the growth of anaerobic ammonium oxidation bacteria, enhance their activity, and thus improve the denitrification efficiency. At the same time, the microelectric field can also change the existence form of pollutants in the sewage, making them more easily utilized by microorganisms, further improving the treatment effect.

[0112] II. Detection of Microbial Indicators

[0113] Take the treated sewage sample and use the cultivation counting method to determine the number of anaerobic ammonium oxidation bacteria, short-cut denitrifying bacteria, acetic acid bacteria and the viable count of the total bioactive bacterial community.

[0114] Table 2:

[0115]

[0116] The above result data shows that the viable counts of anaerobic ammonium oxidation bacteria, short-cut denitrifying bacteria and acetic acid bacteria in the example group all maintain at a relatively high level, indicating that the modified composite filler provides a good attachment carrier and optimizes the microenvironment for the survival of microorganisms; the jet operation ensures sufficient contact between the sewage and the bacterial community and uniform distribution of nutrients; appropriate conditions such as dissolved oxygen, pH value, temperature and carbon-nitrogen ratio fully meet the growth and metabolic requirements of the bacterial community, resulting in high activity of each bacterial community, strong synergistic effect, and efficiently promoting the denitrification and pollution removal reactions in sewage treatment.

[0117] Compared with Comparative Example 1, the modified composite filler in Example 3 provides ideal attachment points and a good nutrient circulation environment for microorganisms; compared with Comparative Example 2, it can be seen the key role of the jet operation in Example 3 in evenly distributing nutrients and maintaining a high viable cell count; compared with Comparative Example 3, it shows that short-range denitrifying bacteria can provide suitable substrates for anaerobic ammonium oxidation bacteria, and acetic acid bacteria can adjust the carbon-nitrogen ratio and improve the microbial living environment, and through the cooperation of the microbial flora, maintain the ecological balance among the flora; compared with Comparative Example 4, it highlights the microelectric field assistance in Example 3 in enhancing the transport of substances inside and outside microbial cells, improving enzyme activity, and maintaining a high viable cell count.

[0118] The above 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 in the protection scope of the present invention.

Claims

1. A short-range denitrification anaerobic ammonium oxidation filter for urban sewage, characterized in that: It includes a mixing area, a biological filter layer area and a sedimentation area. The biological filter layer area is filled with biological fillers, and the biological fillers are modified composite fillers. The surface of the composite fillers is attached with biologically active bacteria. The thickness of the filter layer is 1-3 meters.

2. A short-range denitrification anaerobic ammonium oxidation filter for urban sewage as claimed in claim 1, characterized in that: The composite filler is ceramic particles, carbon nanotubes and titanium dioxide nanoparticles in a mass ratio of (3.5-5.5):(1.2-3.0):(0.2-0.8).

3. A short-range denitrification anaerobic ammonium oxidation filter for urban sewage as claimed in claim 2, characterized in that: The modification method of the composite filler is specifically to mix ceramic particles, carbon nanotubes and titanium dioxide nanoparticles, slowly pour acetone, immerse the composite filler, the mass volume ratio of the composite filler to acetone is 1:5-10 g / mL, and then perform ultrasonic treatment, the ultrasonic power is 200-500W, the ultrasonic time is 30-60min, and after the end, it is dried at 40-60°C for 1-3h, ground, and the particle size is 3-5mm, and the specific surface area is greater than 1000m 2 / g, porosity 40-50%.

4. A short-range denitrification anaerobic ammonium oxidation filter for urban sewage as claimed in claim 1, characterized in that: The biologically active bacteria group includes anaerobic ammonia oxidizing bacteria, short-range denitrifying bacteria and acetic acid bacteria, and the bacterial viability is greater than 1×10 6 cfu / ml.

5. A short-range denitrification anaerobic ammonium oxidation filter for urban sewage as claimed in claim 4, characterized in that: The mass ratio of the anaerobic ammonium oxidizing bacteria, the short-range denitrifying bacteria and the acetic acid bacteria is 50-70:20-40:10-20.

6. A method for treating urban sewage as claimed in claim 1, characterized in that: The urban sewage is passed into the anaerobic ammonium oxidation filter to construct a short-range denitrification anaerobic ammonium oxidation filter for deep denitrification, including the following steps: S1. Pretreatment: The urban sewage is pretreated to remove large suspended solids and floating matter; S2, mixing: the pre-treated sewage and domestic sewage raw water enter the mixing zone in the anaerobic ammonia oxidation filter tank from the water inlet pipe, and the sewage is mixed by jet flow, and the water inlet rate is 10-13L / h; S3, biological reaction filtration: After the mixing, the water enters the biological filter layer area, and is reacted and filtered under the action of biologically active bacteria. The hydraulic retention time is controlled to be 4-6 hours, and the water inlet and outlet speeds are both 0.5-1m / h; S4. Sedimentation: The water that has passed the reaction filtration enters the sedimentation area for sedimentation. The treated water is discharged from the outlet. At the same time, the sedimentation area is backwashed regularly using the backwash water outlet.

7. A method for treating urban sewage as claimed in claim 1, characterized in that: In step S2, the jet flow rate is 10-30% of the total water volume in the mixing zone, the jet pressure is maintained at 0.2-0.5 MPa, the jet time interval is 5-15 minutes, and each jet time is 3-5 minutes.

8. A method for treating urban sewage as claimed in claim 1, characterized in that: During the reaction filtration process in step S3, the dissolved oxygen concentration is controlled at 0.1-0.5 mg / L, the pH value is controlled at 7.5-8.5, the temperature is controlled at 30-35° C., and the carbon-nitrogen ratio is controlled at 1-3.

9. A method for treating urban sewage as claimed in claim 1, characterized in that: In step S3, a micro-electric field is also used to assist the reaction filtration process, the electric field strength is controlled at 0.5-3V / cm, an intermittent power-on mode is adopted, and the ratio of the power-on time to the power-off time is set to (1-3):(2-4).

10. A method for treating urban sewage according to claim 1, characterized in that: In step S4, the water inlet speed in the sedimentation zone is controlled to be 0.1-0.3 m / s.

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