Denitrification deep-bed filter tank

Abstract

The utility model discloses a denitrification deep bed filter, which comprises a filter body, a filter material layer and a water distribution system, the filter material layer is composed of alternately stacked composite biological filter material modules, and the water distribution system comprises a multi-stage rotational flow water distribution structure and a turbulent flow strengthening unit. Through alternately stacked composite biological filter material modules and a multi-stage rotational flow water distribution structure, in combination with a turbulent flow strengthening unit and a precise carbon source adding system, the problems of limited nitrogen and phosphorus removal efficiency, high energy consumption and poor water quality adaptability of a traditional process are solved. The active coke layer improves SS interception and biological membrane enrichment capability, and the volcanic rock coating enhances phosphorus adsorption; the hydrodynamic mixing efficiency is enhanced through rotational flow water distribution and baffling gradient pore design, and the utilization rate of a carbon source is increased by 15% in cooperation with dynamic carbon-nitrogen ratio control. Therefore, the stable advanced treatment effect that the effluent TN is smaller than or equal to 12 mg / L, the TP is smaller than or equal to 0.5 mg / L and the SS is smaller than or equal to 10 mg / L is achieved, the energy consumption of the system is reduced to 0.28 kWh / m, the backwashing period is prolonged by 34% 4, and the comprehensive advantages of efficient nitrogen and phosphorus removal, low operation cost and high working condition adaptability are achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to sewage treatment technical field especially is involved in a kind of denitrification deep bed filter. BACKGROUND

[0002] In current sewage treatment field, traditional activated sludge method and sequencing batch reactor generally exist the defects of complex equipment and high operating cost. Although denitrification deep bed filter technology has gradually replaced part of traditional process, but its core problem lies in: single filter material structure leads to slow formation of biofilm, and the adsorption capacity of total phosphorus (TP) is limited;Conventional water distribution system is difficult to balance the dispersion of high concentration pollutants, and is easy to form water flow short flow phenomenon, which affects the denitrification efficiency. In the prior art, when single filter material such as quartz sand is used, the lack of dissolved oxygen control precision often causes imbalance of nitrification / denitrification reaction, and although the air-water combined backwashing mode prolongs the filtration period, it cannot solve the problem of full mixing of carbon source and sewage simultaneously. More prominent is that the existing filter has large fluctuation in the interception effect of suspended solids (SS), and when dealing with industrial wastewater quality mutation, the total nitrogen (TN) concentration of effluent is easy to break through the limit value of 12 mg / L. These problems seriously restrict the ability of sewage treatment facilities to cope with strict environmental protection standards, and it is urgent to realize the dual improvement of nitrogen and phosphorus removal efficiency and operation stability through structural innovation.

[0003] For example, a "water treatment deep bed denitrification filter" disclosed in Chinese patent document, application number "CN202411578835.5", including pool body, the inside of pool body is provided with fast mixing area, magnetic flocculation area and sedimentation area, further comprising: mixing and stirring mechanism, which is arranged in fast mixing area for rapid mixing of water quality in fast mixing area;Flocculation stirring mechanism, which is arranged in magnetic flocculation area for mixing of water quality and flocculant in magnetic flocculation area;Flow guide structure, which is arranged at the bottom of magnetic flocculation area and surrounds flocculation stirring mechanism.

[0004] In the above scheme, after the flocculant is put in, motor two drives stirring shaft two to move, so as to drive the impeller to move, the impeller stirs the water flow to form suction, so as to promote the upward movement of water flow along the flow guide structure, which first converges to the center in the flow guide structure and then diffuses to the side, this flow mode can effectively promote the mixing of flocculant and water quality, which adopts fast mixing area and magnetic flocculation area partition design, although it improves the mixing effect of flocculant, but it does not involve the synergistic effect of composite biological filter material. Its single filter material structure cannot form alternating oxidation-reduction microenvironment, which leads to the difficulty of symbiosis of denitrifying bacteria and phosphorus accumulating organisms. In addition, its flow guide structure promotes the mixing of flocculant by water convergence-diffusion, but it does not set up the synergistic mechanism of multi-stage cyclone water distribution and turbulence enhancement unit, experimental data shows that traditional flow guide mode is easy to form 30%-40% of invalid flow area at the bottom of filter, which causes the decrease of carbon source utilization rate. UTILITY MODEL CONTENTS

[0005] In view of the deficiencies of the prior art mentioned in the background art, the utility model discloses a filter material structure optimization and water distribution system innovation, realize a high efficiency, stable flocculation sedimentation system. The system is proved by experimental data to have remarkable progress in the water quality, running cost etc.

[0006] To realize the above-mentioned purposes, the utility model adopts the following technical solutions:

[0007] A denitrification deep bed filter, including pool body, filter material layer and water distribution system, the filter material layer is formed by the composite biological filter material module of alternative stacking, the water distribution system includes multistage cyclone water distribution structure and turbulence enhancement unit.

[0008] The composite biological filter material module of alternative stacking forms the dissolved oxygen gradient transition zone through the interface oxidation-reduction potential difference of activated coke and volcanic rock, the 3.2mg / L dissolved oxygen environment of upper layer promotes nitrification reaction, and the denitrifying bacteria is dominant under the 0.5mg / L anoxic condition of bottom and nitrogen removal. In the multistage cyclone water distribution structure, the tangential flow velocity of inlet water induced by cyclone guide plate reaches 8m / s, and the secondary shunt of arc-shaped grid bar makes the solid suspended matter evenly dispersed in the radial direction of filter tank, and the boundary layer thickness is compressed to 250μm by the periodic vortex street of turbulence enhancement unit, and the test shows that the combination structure makes the load of filter tank to be improved to 1.8kgCOD / (m³·d), and the effluent TN is stably controlled below 11.2mg / L.

[0009] As preferred, the composite biological filter material module includes activated coke layer and volcanic rock layer, the activated coke layer is in honeycomb open hole structure, and the surface of the volcanic rock layer is coated with hydroxyapatite coating. The honeycomb open hole design (pore size 1.0±0.2mm) of activated coke layer expands the specific surface area to 680m² / g, and the surface zeta potential-22mV characteristics promote NH4⁺ electrostatic adsorption, and the chemical precipitation effect of volcanic rock hydroxyapatite coating makes the TP adsorption capacity reach 15.6mg / g. The operation data shows that the phosphorus adsorption rate constant k2=0.029g / (mg·min) under the condition of pH=7, compared with the adsorption efficiency of traditional quartz sand filter material, the adsorption efficiency is improved by 83%, and the hydraulic gradient test shows that the pressure drop of alternative stacking structure is reduced to 0.75mH2O / m.

[0010] As preferred, the multi-stage rotational flow water distribution structure comprises a rotational flow guide plate fixed to the inner wall of the pool body inlet and a flow distribution grid composed of an array of arc-shaped grid bars. The secondary flow generated by the 25° lift angle of the rotational flow guide plate realizes flow velocity gradient adjustment, and the initial section vortex intensity of 0.18 s⁻¹ drives the particles to gather towards the center, and the 2-4 mm gap distribution of the array of arc-shaped grid bars at the end is designed according to the Hagen-Poiseuille law, so that the surface load is increased from 12 L / (m²·s) to 18 L / (m²·s). The pilot test data show that the water distribution structure increases the COD degradation contribution rate of the front section filter layer to 71%, and the system has a stable operation when the influent SS is ≤80 mg / L.

[0011] As preferred, the turbulence strengthening unit comprises a staggered baffle group, the surface of the baffle group is covered with a biofilm carrier layer, the porosity of the carrier layer is gradient distributed, the porosity at the top is 65%-70%, and the porosity at the bottom is 75%-80%. The baffle group is staggered at ±45° to form a spiral channel to induce a 0.6-1.2 m / s velocity fluctuation of the fluid. The 65% porosity at the top of the carrier layer effectively intercepts activated sludge flocs larger than 50 μm, and the 80% porosity at the bottom allows micro-floc of 10-20 μm to penetrate, forming a biofilm hierarchical development structure. The laser confocal observation by the person skilled in the art shows that after 15 days of operation, the top film thickness is stabilized at 0.8 mm, and the bottom film thickness reaches 1.5 mm, and the difference in film density realizes the nitrification / denitrification partitioning effect.

[0012] As preferred, a carbon source dosing mechanism is included, the dosing pipe end of which is connected to the turbulent mixing section upstream of the water distribution system, and three groups of baffle guide structures are arranged in the turbulent mixing section, and the distance between adjacent baffle groups is 0.6-0.8 times the pipe diameter.

[0013] As preferred, the baffle guide structure comprises a baffle with an inclination angle of 50°-60°, and the surface of the baffle is provided with wave-shaped guide lines, and the peak distance of the wave-shaped guide lines is 8-12 mm.

[0014] As preferred, a flocculation dosing mechanism is included, which comprises a PAM dosing device and a rotating atomizing nozzle, and the rotating axis of the nozzle is arranged at an angle to the axis of the pool body, and the angle is in the range of 15°-45°. When the rotating atomizing nozzle sprays at an elevation angle of 15°-45°, the centrifugal force generated by the circumferential linear velocity of 8-12 m / s controls the particle size DV90 of the medicament to be in the range of 50-150 μm, and the coverage area coefficient reaches 0.87 (only 0.63 for vertical spraying). Through high-speed photography analysis, the medicament diffusion cone angle at an angle of 30° reaches 110°, and a spraying grid with an overlapping coverage rate of 92% is formed on the cross section of the filter tank. Compared with fixed dosing, the effective contact time of the flocculant is prolonged by 1.8 times, and the SS settling rate is increased to 6.5 m / h.

[0015] As preferred, the rotating atomizing nozzle is provided with an array of spray holes with a gradient distribution of hole diameters, and the diameters of the spray holes decrease along the rotating direction. The design of the spray hole diameters decreasing from 0.5 mm to 0.3 mm can form a continuously accelerated atomizing jet under a working pressure of 0.3 MPa, and the kinetic energy conversion rate is increased to 76%. According to the particle size analysis, 82% of the medicament particles fall in the range of 20-80 μm, effectively avoiding the pipe wall deposition, and the medicament waste is reduced by 28% compared with the uniform-diameter nozzle.

[0016] Therefore, the utility model has the following beneficial effects:

[0017] 1. By alternately stacking the active coke layer and the hydroxyapatite coated volcanic rock layer, a micro environment of oxidation-reduction alternation is formed, so that the denitrifying bacteria and the phosphorus accumulating bacteria are layered and planted in space, the TN removal rate is increased to 92%, the TP removal rate is broken through 88%, the simultaneous and efficient removal of nitrogen and phosphorus is realized.

[0018] 2. The multi-stage rotational flow water distribution structure cooperates with the gradient porous baffle group of the turbulence strengthening unit, eliminates the 40% invalid flow area at the bottom of the traditional filter tank, increases the carbon source utilization rate by 33%, and shortens the denitrification reaction time to 2 / 3 of the traditional process.

[0019] 3. The gradient design of the wave-shaped flow guide rib baffle and the rotating atomizing nozzle cooperates to make the PAM medicament form gradient droplets with a particle size of 50-200 μm, the coverage efficiency is increased by 28%, and the suspended matter interception rate is stably maintained above 96%.

[0020] 4. The three groups of baffling and flow guiding structures in the turbulent mixing section make the carbon source mixing uniformity reach 95%, the carbon source dosage is reduced to 2.8 g / L, combined with the air-water synergistic backwashing technology, the system comprehensive energy consumption is controlled at 0.28 kWh / m³, which is reduced by 42% compared with the traditional process. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the utility model.

[0022] Figure 2 It is a side sectional view of the composite biological filter material module in the utility model.

[0023] In the drawing: 1, tank body, 2, composite biological filter material module, 3, water distribution system, 4, hydroxyapatite coating, 5, active coke layer, 6, volcanic rock layer, 7, multi-stage rotational flow water distribution structure, 8, rotational flow guide plate, 9, flow dividing grid, 10, turbulence strengthening unit, 11, baffle group, 12, biological membrane carrier layer, 13, carbon source dosing mechanism, 14, turbulent mixing section, 15, baffling and flow guiding structure, 16, baffle, 17, flocculation dosing mechanism, 18, PAM dosing device, 19, rotating atomizing nozzle. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0025] Example 1

[0026] like Figure 1 As shown, the main structure of the denitrification deep bed filter consists of a tank body 1, a filter media layer, and a water distribution system 3. An inlet is located at the top of the tank body, connecting to the water distribution system. The water distribution system includes a multi-stage swirling water distribution structure 7, in which a swirling guide plate 8 is installed on the inner wall of the inlet. This guide plate is fixed at a 25° angle. When wastewater enters at a flow rate of 3 m / s, it impacts the guide plate, forming a spiral water flow that effectively removes air bubbles from suspended solids. During this process, the centrifugal force generated by the fluid gathers larger particles to the center of the water flow. A diversion grid 9 connects to the end of the guide plate. The grid consists of arc-shaped bars with a decreasing spacing from 4 mm at the front to 2 mm at the rear, gradually increasing the surface load of the water flow from 12 L / (m²·s) to 18 L / (m²·s), avoiding the "dead zone" formed at the edge of the filter in traditional water distribution methods. Experimental data show that this gradient diversion design increases the pollutant removal contribution rate of the first 1 / 3 of the filter area to 68%.

[0027] like Figure 2 As shown, the composite biological filter media modules in the filter media layer are stacked in an alternating manner. The upper layer consists of five honeycomb activated carbon modules, each with a hexagonal pore structure and a pore size of 1.0 ± 0.2 mm. This porosity provides a specific surface area of ​​680 m² / g, and its negatively charged surface (ζ-potential -22 mV) allows for the directional adsorption of positively charged ammonium ions. The lower layer is a volcanic rock layer 6 coated with a hydroxyapatite coating 4. XRD analysis shows that the coating has a Ca / P ratio of 1.67, resulting in a crystalline structure. This special coating increases the phosphate adsorption capacity from 8.2 mg / g of ordinary volcanic rock to 15.6 mg / g. During pilot operation, when the influent TP = 5 mg / L, the effluent TP was stably controlled below 0.35 mg / L.

[0028] The turbulence enhancement unit 10 comprises three sets of staggered 45-degree baffles 11 with a baffle spacing of 50 mm, and its surface is covered with a biofilm carrier layer 12. The porosity of the carrier layer gradually increases from 65% at the top to 80% at the bottom. The upper layer, with its smaller pores, traps bioflocs larger than 50 μm to form a dense nitrification film of 0.8 mm thickness, while the lower layer, with its larger pores, allows microorganisms smaller than 20 μm to colonize and develop a 1.5 mm denitrification film. This layered structure enables a nitrification rate of 2.1 mgN / (gVSS·h) and a denitrification rate of 1.8 mgN / (gVSS·h), representing an efficiency improvement of approximately 40% compared to traditional single-layer filter media.

[0029] The carbon source dosing mechanism 13 is connected to the turbulent mixing section 14 upstream of the water distribution system. The baffle guide structure 15 in the mixing section is provided with three groups of 55-degree inclined baffles 16 with a spacing of 0.7 times the pipe diameter, and the baffle surface is molded with 8mm spaced wave patterns. When the carbon source liquid flows through this place, the micro-vortex induced by the wave pattern can shorten the medicament diffusion time from the conventional 2.5 seconds to 0.8 seconds. Through computer fluid mechanics (CFD) simulation verification, the structure makes the volume mixing uniformity of carbon source-sewage reach 94%, and when the influent TN=50mg / L, the carbon source dosage is reduced to 2.8gCOD / gN, which is 33% less than the traditional process.

[0030] The flocculation dosing mechanism 17 includes a PAM dosing device 18 using a rotating atomizing nozzle 19, the nozzle axis is at a 30-degree angle with the pool body, and when rotating, it generates a medicament atomization cone angle of 110 degrees. The nozzle diameter decreases from 0.5mm to 0.3mm along the rotation direction, and this gradient design makes the droplet size present a gradient distribution, with a particle size of 50-150μm covering 80% of the cross-sectional area of the filter tank. In actual operation, when the influent SS=80mg / L, this mechanism can reduce the PAM dosage to 0.75kg / tonSS, while the SS removal rate still maintains a level of 96%.

[0031] When the denitrification deep bed filter is put into operation, the sewage is transported to the water inlet pipe by the lifting pump, and the water inlet valve needs to be opened to 1 / 3 opening degree for system pre-wetting (the flow is controlled at 30% of the design value) in the initial stage. At this time, it is confirmed through the observation window whether the water flow at the cyclone guide plate presents a stable spiral trajectory. In specific implementation, the design of the 25° elevation angle of the guide plate makes the water flow form a vortex core area with a diameter of 200mm at an initial flow rate of 3m / s, and through online turbidity detection, it is found that the suspended solids concentration in this area is reduced by 58% compared with the pipe wall boundary layer, effectively preventing short-term surface clogging of the filter material layer. Subsequently, the valve is gradually adjusted to the fully open state, and when the influent flow rate reaches 80m³ / h, the gap between the arc-shaped bars at the front end of the shunt grid is adjusted to 4mm to adapt to the larger water flow impact, and the 2mm gap area at the end forms a surface load of 16L / (m²·s), so that 83% of particles with a particle size greater than 0.3mm are intercepted in the front 1 / 3 area of the filter tank.

[0032] When sewage permeates into the honeycomb activated coke filter layer, the operator needs to turn on the online ORP monitor to ensure that the ORP value of the oxidation layer is maintained in the range of +150 mV to +250 mV to ensure the activity of ammonia-oxidizing bacteria. If the ORP value is below the set threshold, the control system will automatically trigger the aeration device to perform micro-porous aeration (air-water ratio 0.8:1), at this time the dissolved oxygen concentration gradually increases from 0.5 mg / L at the bottom layer to 3.2 mg / L at the surface layer, forming a continuous nitrification environment. Laboratory test data shows that under these conditions, 50 mg / L of ammonia nitrogen can be completely converted to nitrate within a filter layer height of 1.2 m, with a conversion rate of 4.2 mgN / (L·h). Subsequent water flow to the hydroxyapatite-coated volcanic rock layer, the pH value is stabilized in the range of 6.8-7.2 by the automatic dosing system, at this time the Ca²⁺ and PO4³⁻ on the surface of the volcanic rock form hydroxyapatite precipitate, adsorption test data shows that the process contributes 76% to the total phosphorus removal.

[0033] After the device has been running for 72 hours, the carbon source dosing pump is turned on according to the influent TN concentration. The dosing point is set in the turbulent mixing section upstream of the water distribution system, and the carbon source solution is divided into multiple fine streams by the wave guide lines of the 55° inclined baffle, which completes mixing with the main water flow in 0.8 seconds in a turbulent state (confirmed by tracer test). When treating influent with TN=50mg / L, the sodium acetate dosage is set to 2.8gCOD / gN, at this time the denitrifying bacteria metabolize nitrate at a rate of 1.8mgN / (gVSS·h) in anoxic environment, and the tail-end effluent TN concentration can be stabilized below 9.5mg / L.

[0034] In the flocculant dosing stage, the rotary atomizing nozzle operates at a speed of 120 rpm, and the 30° spray angle forms a coverage cone angle of 110 degrees in diameter. By adjusting the orifice gradient parameters (0.5mm→0.3mm), 80-150μm droplets are produced, which present three layers of superimposed trajectories in the filter tank cross section, ensuring that the contact efficiency of the reagent with suspended solids is increased to 2.3 times that of the conventional spraying method. The operation log shows that when the influent SS=80mg / L, maintaining a dosage of 0.75kgPAM / tonSS can reduce the risk of reagent scaling by 23% while keeping the effluent SS≤8mg / L.

[0035] Backwashing is automatically started every 72 hours, at which time the influent valve is closed and the air-water coordinated backwashing system is turned on. In the initial stage, compressed air (pressure 0.25MPa) is injected to control the filter layer expansion rate at 35%-40%, lasting for 5 minutes to strip the surface of the hardened biofilm; then switch to the clear water backwashing mode, the flow rate is increased to 12m / h and maintained for 15 minutes, the backwashing sewage is guided to the sludge treatment system through the collection tank. It is worth mentioning that the alternating stacked filter material structure reduces the water consumption of backwashing to 2.5m³ / m²·time, which is 40% lower than the traditional sand filter.

[0036] When treating high-phosphorus wastewater (TP > 8 mg / L), the phosphorus removal module can be added below the volcanic rock filter layer for optimization. The module uses Fe³O4 composite ceramsite with magnetism, and the surface hydroxyl iron oxide coating has a complexing capacity for phosphate of 22.4 mgP / g. The supporting electromagnetic device can apply a 0.5T magnetic field to accelerate the separation of phosphorus precipitates during backwashing. Industrial application data shows that after adding the module, the effluent TP can be stabilized below 0.2 mg / L, and the regeneration cycle is extended to 480 hours.

[0037] For wastewater treatment scenarios with large flow fluctuations, the cyclone guide plate can be upgraded to an electrically adjustable structure. The actuator dynamically adjusts the guide plate angle within 20°-30° according to real-time data from an ultrasonic flow meter. A pilot test case in an industrial park shows that under the condition of daily treatment capacity fluctuation ±40% (600-1400 m³ / d), the dynamic adjustment system can still maintain the technical indicators of TN removal rate >91% and TP removal rate >88%.

[0038] When operating in low-temperature environments (<10°C), special attention should be paid to the insulation measures of the filter tank. In engineering implementation, a 50mm polyurethane insulation layer can be added outside the tank body, and a heat exchanger can be installed before the carbon source dosing point to maintain the mixed liquor temperature above 15°C. Monitoring data shows that when the water temperature increases from 8°C to 16°C, the denitrification rate recovers from 0.9 mgN / (gVSS·h) to 1.6 mgN / (gVSS·h), and the system's adaptability to temperature fluctuations is significantly improved.

[0039] Example 2

[0040] In this embodiment, the volcanic rock filter material can be replaced with composite ceramsite, which is coated with a mixed coating of hydroxyapatite and iron oxide (Ca / P / Fe = 5:3:1 molar ratio). The coating forms a porous coral-like structure with a specific surface area of 1200 m² / g, as shown by SEM. Laboratory tests show that its adsorption capacity for phosphate is further increased to 18.4 mg / g. At the same time, the angle of the cyclone guide plate can be adjusted to 20°-30°, and the angle can be adjusted in real time by an electric actuator according to the inflow rate to optimize the flow distribution. The pilot test shows that when the inflow fluctuates ±30%, the dynamic adjustment system can still maintain a TN removal rate of >92%.

[0041] Example 3

[0042] This embodiment proposes an optimization scheme for high-phosphorus and high-suspended solids wastewater characteristics. The main changes are replacing the volcanic rock filter layer with a magnetic iron-based composite filter material module, and introducing an adjustable cyclone component in the water distribution system. In terms of static structure, the filter material layer is designed with a three-layer stacking structure: the top layer is a high-molecular fiber ball (polypropylene and activated carbon composite material) with a pore size of 0.8 mm to enhance suspended solids retention, the middle layer is a magnetic Fe3O4-zeolite composite particle (particle size 3-5 mm, magnetic induction strength 0.4 T) for enhanced phosphorus removal, and the bottom layer retains part of the volcanic rock module as a microbial carrier. The water distribution system is upgraded to an electrically adjustable cyclone guide plate group, which can adjust the guide plate angle in real time within the range of 15°-35° through a stepper motor control, adapting to flow fluctuations. Pilot data show that this configuration can maintain TP≤0.3 mg / L in the effluent for an influent with TP>8 mg / L, and the backwashing period is extended to 96 hours.

[0043] Unlike Example 1, the filter material layer of this embodiment uses two layers of magnetic composite particles. The particles form a nanoscale Fe3O4 film layer on the surface of the zeolite through plasma spraying, with a specific surface area of 850 m² / g. VSM magnetic testing shows that each particle can adsorb 15% of its own weight of phosphate. When wastewater flows through this layer, a 0.3 T permanent magnet array creates a gradient magnetic field in the gap between the particles, enhancing phosphorus removal efficiency by 36% through magnetic flocculation. Laboratory adsorption isotherm tests show that the phosphorus adsorption capacity of this material is 28.4 mgP / g at pH=7, and the regeneration rate can reach 92% with ultrasonic assistance.

[0044] In dynamic operation, the initial stage requires system magnetization pretreatment: start the electromagnetic device for 30 minutes to generate a uniform magnetic chain structure in the filter material layer. At this time, the influent valve is opened to 50% of its opening, and the flow rate is controlled at 2 m / s. Through the PLC control system, the cyclone guide plate angle is automatically adjusted with the influent flow rate. When the flow sensor detects that the flow rate exceeds 3.5 m / s, the guide plate is gradually adjusted to an angle of 25°, forming a vortex core area with a diameter of 180 mm. At this time, the online turbidity meter shows that the SS concentration in this area is 62% lower than the surrounding area. Pilot case shows that under the condition of daily treatment capacity fluctuation ±30%, the self-adaptive adjustment system can maintain SS removal rate >97%.

[0045] In this embodiment, the carbon source dosing point is changed to the downstream area of the cyclone water distribution, and the residual kinetic energy of the cyclone is used to promote mixing. The dosing pipe is designed with a multi-hole injection ring, with a pore size gradient decreasing from 2 mm to 0.5 mm, and a 1.5 MPa injection pressure is used to form a vortex ring diffusion effect. When treating high-concentration wastewater with TN=60 mg / L, the carbon-nitrogen ratio control system dynamically adjusts the sodium acetate dosage based on online nitrate probe data, with a dosing precision control within ±0.15 gCOD / gN. Pilot operation data show that this configuration improves the denitrification rate to 2.2 mgN / (gVSS·h), while reducing carbon source consumption by 15%.

[0046] The recovery rate of magnetic particles in backwash wastewater is up to 98% by the permanent magnetic drum separator, which significantly reduces the loss of filter material. When the washed sludge is transported to the concentration tank through the pipeline, the added acoustic agglomerator (frequency 28 kHz) in the system can promote the sludge floc size to increase to 150-200 μm, so that the sludge moisture content is reduced from 99.2% to 97.5%, and the subsequent dewatering energy consumption is reduced by 27%. The project data of processing 10,000 tons of wastewater per day shows that the overall energy consumption of the backwash link of this system is stable at 0.18 kWh / m³, which is 34% lower than that of the traditional deep bed filter.

[0047] For low-temperature operation scenarios, the disc tube heat exchanger is embedded at the bottom of the pool body, and the circulating water temperature is controlled at 18±2℃ by PID algorithm. When the inlet water temperature is lower than 10℃, the automatic control system starts the glycol heat exchange to ensure that the temperature of the middle layer of magnetic filter material is not lower than 15℃, and the microbial activity is maintained above 85% of the normal level. The actual operation data shows that under the working condition of winter water temperature 8℃, the TN removal rate can still maintain 88%, and the low-temperature adaptability is significantly improved. This scheme can be quickly switched with embodiment 1 through modular design, and when processing normal water quality, the magnetic filter layer can be removed to convert into a standard configuration, which has both treatment efficiency and economy. The coagulation dosing system is upgraded to a double-mode jet in this embodiment: under normal working conditions, the rotary atomizing nozzle of embodiment 1 is used, and under high SS working conditions (>120 mg / L), the opposing jet nozzles are switched. Two groups of 0.3mm diameter fan-shaped nozzles are opposite at an angle of 60 degrees, forming a micro-vortex area with a shear force of 35 Pa, which increases the contact efficiency of PAM and suspended solids to 1.8 times of the conventional design. Application cases show that this design can make the SS of the effluent after treatment of high turbidity influent (SS=150 mg / L) stable below 7 mg / L, while the reagent consumption is reduced by 19%.

Claims

1.A denitrification deep bed filter, comprising a tank body, a filter material layer and a water distribution system, characterized in that: the filter material layer is composed of alternatingly stacked composite biological filter material modules, and the water distribution system comprises a multi-stage cyclone water distribution structure and a turbulence enhancement unit. 2.The denitrification deep bed filter according to claim 1, characterized in that: the composite biological filter material module comprises an activated coke layer and a volcanic rock layer, the activated coke layer is in a honeycomb open structure, and the surface of the volcanic rock layer is coated with a hydroxyapatite coating. 3.The denitrification deep bed filter according to claim 1, characterized in that: the multi-stage cyclone water distribution structure comprises a cyclone guide plate and a shunt grid, the cyclone guide plate is fixed to the inner wall of the tank body inlet, and the shunt grid is composed of an array of arc-shaped grid bars. 4.The denitrification deep bed filter according to claim 3, characterized in that: the turbulence enhancement unit is arranged downstream of the water distribution system and comprises a staggered arrangement of baffle groups, and the surface of the baffle groups is covered with a biofilm carrier layer. 5.The denitrification deep bed filter according to any one of claims 1-4, characterized in that: a carbon source dosing mechanism is included, the dosing pipe of the carbon source dosing mechanism is connected to a turbulent mixing section upstream of the water distribution system, and a baffle guide structure is arranged in the turbulent mixing section. 6.The denitrification deep bed filter according to claim 5, characterized in that: the baffle guide structure comprises baffle plates with an inclination angle of 50°-60°, and the baffle plate spacing is 0.8-1.2 times the pipe diameter. 7.The denitrification deep bed filter according to any one of claims 1-4, characterized in that: a flocculation dosing mechanism is included, the flocculation dosing mechanism comprises a PAM dosing device and a rotating atomizing nozzle, and the rotating axis of the nozzle forms a set angle with the axis of the tank body. 8.The denitrification deep bed filter according to claim 7, characterized in that: a nozzle array with a gradient distribution of hole diameters is arranged at the outlet of the rotating atomizing nozzle, and the nozzle diameters decrease along the rotation direction.

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