Sludge phosphorus release and phosphorus crystal recovery device

Abstract

The invention relates to the technical field of water treatment, in particular to a sludge phosphorus release and phosphorus crystal recovery device which comprises a phosphorus release mechanism and a phosphorus crystal recovery mechanism, and the phosphorus release mechanism comprises a sludge concentration unit, a sludge breaking assembly and a sludge dewatering unit; the sludge disintegration assembly comprises a sludge disintegration unit and a pH value adjusting unit, the phosphorus crystal recovery mechanism comprises an outer shell, a middle shell, an inner shell, a plug flow stirring assembly, a folded plate vortex assembly, a modular vortex assembly, an inclined plate assembly and a micro-nano aeration disc, the outer shell, the middle shell and the inner shell are combined to form a unique circulation channel, and the outer shell, the middle shell and the inner shell are combined with the micro-nano aeration disc; according to the method, small-particle crystals are used as seed crystals to enter a circulating channel, so that ready-made nucleation sites are provided for a solution, the critical supersaturation degree required for forming new crystal nucleuses is reduced, the probability of spontaneous nucleation is reduced, the generation of irregular dendritic or needle-shaped crystals is inhibited, and the formation of more compact and uniform prismatic or sheet-shaped large-particle crystals is promoted; and efficient phosphorus release and phosphorus crystal recovery are realized.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a sludge phosphorus release and phosphorus crystal recovery device. Background Art

[0002] At present, in order to achieve effective recovery of phosphorus in sludge, the phosphorus in the sludge (solid phase) needs to be released into the liquid phase as much as possible. The efficient release of phosphorus is the key step in phosphorus recovery.

[0003] The existing phosphorus release technologies mainly include:

[0004] ① Physical decomposition method: Use thermal hydrolysis, ultrasound, mechanical ball milling and other methods to break the microbial cells in the sludge and release the phosphorus-containing substances inside and outside the cells into the liquid phase. Sludge thermal hydrolysis needs to be carried out under high temperature and high pressure conditions (150-190℃, 0.7-2.6MPa). It is usually used as a pretreatment process in conjunction with anaerobic digestion process. The equipment is complex, operation and maintenance are difficult, investment and energy consumption are high, and the odorous gas produced is difficult to treat. At present, there are only a few engineering application cases; although ultrasonic decomposition is efficient, the reaction time is short (10-60min), and the equipment is simple, it is currently in the laboratory research stage due to its high power consumption. Actual engineering applications need to overcome the defect of high power consumption.

[0005] ② Chemical decomposition method: Add acid, alkali or H2O2, ozone and other chemical agents to the residual sludge to destroy the microbial cell structure and release the phosphorus-containing substances inside and outside the cells into the liquid phase. The acid-base decomposition method has the characteristics of simple process and mature technology, but the existing sludge full-scale acid-base decomposition or H2O2, ozone oxidation and other methods have high drug consumption costs and are still difficult to achieve engineering application.

[0006] ③ Biological phosphorus release method: release phosphorus through anaerobic digestion or enzymatic biological enhanced phosphorus release. Enzymatic biological enhanced phosphorus release technology has high reagent costs and is currently in the laboratory research stage; anaerobic digestion is the most widely used sludge disposal technology in engineering, with the advantages of mature technology and low operating costs, but this method has a slow phosphorus release rate, a long time (the sludge needs to be digested anaerobically for 20 to 30 days), a large reaction device, and high construction investment. If you need to increase the anaerobic phosphorus release rate and shorten the anaerobic phosphorus release time, you need a sufficient carbon source. The available carbon source in the residual sludge discharged from the biochemical system has basically been consumed in the front-end biochemical system, and a large amount of carbon source is needed to meet the requirements.

[0007] ④ Sludge incineration-wet leaching process: After dehydration and drying, the sludge is incinerated into ash, and then acid and alkali are used to leach phosphorus. The phosphorus in the sludge incineration ash mainly exists in the form of combination with metals such as Ca, Mg, Fe, and Al in the ash, which cannot be absorbed and utilized by plants. In addition, the heavy metal substances in the sludge are still retained in the ash after incineration. It is also necessary to separate the phosphorus in the sludge ash from the heavy metals and convert the phosphorus into a form that can be used by plants. The process is complicated and the cost of phosphorus recovery is high.

[0008] ⑤Combination method: Use thermal hydrolysis-acid leaching, acidification-microwave radiation, ultrasound-ozone, ultrasound-alkaline hydrolysis and other combined technologies to destroy the microbial cell structure in the sludge and release the phosphorus-containing substances into the liquid phase. Compared with a single technology, the combination technology can combine the advantages of various technologies and is the trend of technological development in this field.

[0009] Among the existing sludge phosphorus release methods, part of the phosphorus released into the liquid phase by physical breakdown method, chemical breakdown method and some combined breakdown processes exists in the form of organic phosphorus compounds (organophosphorus). Organic phosphorus compounds are difficult to remove by coagulation precipitation method, and phosphorus cannot be recovered by crystallization precipitation method. If it is necessary to improve the recovery rate of phosphorus resources in sludge, it is also necessary to further increase the content of orthophosphate in the residual sludge phosphorus release liquid phase.

[0010] Because the existing sludge phosphorus release and phosphorus recovery technologies and equipment are expensive or the systems are complex, sewage treatment plant sludge is mostly disposed of by direct landfill or incineration after concentration and dehydration, and the phosphorus in the sludge is not recycled as a resource.

[0011] In summary, a device with a simplified structure and capable of achieving efficient phosphorus release and phosphorus crystal recovery is designed to solve the problems existing in the prior art. Summary of the invention

[0012] The object of the present invention is to provide a device with a simplified structure and capable of achieving efficient phosphorus release and phosphorus crystal recovery. The specific technical scheme is as follows:

[0013] A sludge phosphorus release and phosphorus crystal recovery device, comprising a phosphorus release mechanism and a phosphorus crystal recovery mechanism;

[0014] The phosphorus release mechanism comprises a sludge concentration unit, a sludge breaking component and a sludge dehydration unit. The sludge concentration unit is provided with a residual sludge inlet, a concentrated sludge outlet and a supernatant outlet; the sludge breaking component comprises a sludge breaking unit and a pH value adjustment unit arranged in series;

[0015] The phosphorus crystal recovery mechanism includes a shell assembly, a liquid inlet pipe, a liquid discharge pipe, a discharge port, a plug flow stirring assembly, a folded plate vortex assembly, a modular vortex assembly, an inclined plate assembly and a micro-nano aeration disk. The shell assembly includes an outer shell, a middle shell and an inner shell which are sequentially sleeved from the outside to the inside; the upper end and the lower end of the outer shell are both closed ends, and it includes a first cylindrical cylinder and a first conical cylinder which are arranged in series from top to bottom; the upper end and the lower end of the middle shell are both provided with openings, and the middle shell is arranged in the first cylindrical cylinder, and the middle shell includes a second cylindrical cylinder and a second conical cylinder which are arranged in series from top to bottom; the upper end and the lower end of the inner shell are both provided with openings, and the inner shell includes a third cylindrical cylinder, a third conical cylinder and a bottom cylindrical cylinder which are arranged in series from top to bottom, and the lower end of the bottom cylindrical cylinder is located outside the middle shell and in the first conical cylinder; the third cylindrical cylinder The inner cavities of the middle shell, the third conical cylinder and the bottom cylindrical cylinder are connected to form a first water flow rising channel, a water flow descending channel is formed between the inner wall of the middle shell and the outer wall of the inner shell, a second water flow rising channel is formed between the inner wall of the outer shell and the outer wall of the middle shell, and the lower inner cavity of the first conical cylinder forms a crystal gathering area; the plug flow stirring assembly and the folded plate vortex assembly are arranged in the first water flow rising channel along the up and down directions, the liquid inlet pipe is connected with the third cylindrical cylinder and the lower end of the liquid inlet pipe is located above the stirring blades in the plug flow stirring assembly; the modular vortex assembly is arranged in the water flow descending channel; the inclined plate assembly is arranged in the second water flow rising channel, and the discharge port is connected with the crystal gathering area; the micro-nano aeration disk is located at the upper part of the crystal gathering area and directly below the bottom cylindrical cylinder; the discharge pipe is connected with the second water flow rising channel;

[0016] The residual sludge enters the sludge concentration unit through the residual sludge feed port for treatment; the supernatant obtained after the treatment enters the phosphorus crystal recovery mechanism through the supernatant discharge port and the liquid inlet pipe; the concentrated sludge obtained after the treatment is discharged through the concentrated sludge discharge port, a part of the concentrated sludge enters the sludge cracking unit through the first pipeline for sludge cracking treatment, and another part of the concentrated sludge enters the sludge dehydration unit through the second pipeline for sludge dehydration treatment, and the sludge dehydrated liquid after the sludge dehydration treatment enters the phosphorus crystal recovery mechanism through the liquid inlet pipe; the cracked sludge after the cracking treatment enters the pH value adjustment unit for pH value adjustment, and then is transported to the residual sludge feed port through the third pipeline to circulate to the sludge concentration unit.

[0017] Preferably, the sludge concentration unit is a gravity concentration tank; the mass or flow ratio of the sludge entering the sludge decomposition unit through the first pipeline for sludge decomposition treatment to the concentrated sludge discharged from the concentrated sludge discharge port is 0.1-0.2; the control range of the pH value in the sludge decomposition unit is 10.8-11.5; the control range of the pH value in the pH value adjustment unit is 9-10;

[0018] After the sludge whose pH value has been adjusted by the pH adjusting unit intersects with the residual sludge conveying pipeline through the third pipeline, the flow time of the mixed sludge from the intersection point to the residual sludge feed inlet outlet is not less than 3 seconds.

[0019] Preferably, the sludge breaking unit comprises a first shell, a first stirring assembly, a first sludge inlet pipe and a first sludge outlet pipe;

[0020] The first shell includes a first body having a first accommodating cavity, and the first mud inlet pipe and the first mud outlet pipe are both arranged on the first body and communicated with the first accommodating cavity;

[0021] The first body is provided with a first drug adding tube communicating with the first accommodating cavity;

[0022] The first stirring assembly includes a first driving power source, a first stirring shaft and a first stirring blade, wherein the first driving power source is disposed on the first housing; the connecting end of the first stirring shaft is connected to the output end of the first driving power source, and the free end of the first stirring shaft is disposed in the first accommodating cavity and is provided with the first stirring blade;

[0023] The first pipeline is communicated with the first mud inlet pipe, and the first mud outlet pipe is communicated with the pH value adjusting unit through the fourth pipeline.

[0024] Preferably, it also includes a first pH controller, the first body is provided with a measuring hole connected to the first containing cavity, the first pH controller is arranged at the measuring hole to measure the pH value of the sludge; the first pH controller is connected to an external PLC control system, and the first pH controller measures the pH value of the sludge through a first measuring electrode; the first measuring electrode is arranged at the measuring hole and a protective net is provided on the outside of the measuring electrode.

[0025] Preferably, the inner wall of the first accommodating cavity is further provided with a plurality of protrusions facing the center of the first accommodating cavity; the protrusions are hemispherical protrusions with a radius of 40-80 mm; and the plurality of protrusions are evenly distributed on the inner wall of the first accommodating cavity.

[0026] Preferably, the first stirring shaft is provided with multiple layers of the first stirring blades at intervals along the axial direction thereof;

[0027] The first body is also provided with a first odor collecting pipe for collecting odor generated in the first accommodating chamber; the first shell also includes an opening connected to the first accommodating chamber, and a detachable cover is provided at the opening, and the first driving power source, the first dosing pipe, the first pH controller and the first odor collecting pipe are all arranged on the detachable cover.

[0028] Preferably, the pH value adjusting unit comprises a second shell, a second stirring assembly, a second mud inlet pipe and a second mud outlet pipe;

[0029] The second shell includes a second body having a second accommodating cavity, and the second mud inlet pipe and the second mud outlet pipe are both arranged on the second body and are both communicated with the second accommodating cavity;

[0030] The second body is provided with a second drug adding tube communicating with the second accommodating cavity;

[0031] The second stirring assembly includes a second driving power source, a second stirring shaft and a second stirring blade, wherein the second driving power source is arranged on the second housing; the connecting end of the second stirring shaft is connected to the output end of the second driving power source, and the free end of the second stirring shaft is arranged in the second accommodating cavity and is provided with the second stirring blade;

[0032] The fourth pipeline is communicated with the second mud inlet pipe, and the second mud outlet pipe is communicated with the third pipeline.

[0033] Preferably, a water collecting tank is provided at the upper part of the first columnar barrel, and the liquid rising through the second water flow rising channel is collected in the water collecting tank and then discharged through the drain pipe; the micro-nano aeration plate is located 0.2 to 0.3 m below the bottom end of the bottom columnar barrel.

[0034] Preferably, the plug-flow stirring assembly comprises a third driving power source, a third stirring shaft and a third stirring blade, the connecting end of the third stirring shaft is connected to the output end of the third driving power source, and the third stirring blade is arranged on the free end of the third stirring shaft; the water outlet end of the liquid inlet pipe is located 20-50 cm above the third stirring blade;

[0035] The folded plate vortex assembly is located directly below the plug-flow stirring assembly, and the folded plate vortex assembly includes a first folded plate and a second folded plate arranged in parallel, the first folded plate includes a plurality of connecting plates connected in sequence, and the angle α between two adjacent connecting plates is 80°-100°; the first folded plate and the second folded plate are in a mirror image structure;

[0036] The modular vortex assembly includes a plurality of vortex monomers stacked or spaced apart, wherein the vortex monomer is a hollow columnar body formed by a first vertical plate, a second vertical plate, an upper arc-shaped outer frame, an upper arc-shaped inner frame, a lower arc-shaped outer frame and a lower arc-shaped inner frame; a vortex sheet is installed in the vortex monomer, and the cross section of the vortex sheet is at least one of a triangle, a semicircle and a rectangle;

[0037] The inclined plate assembly includes a plurality of sedimentation inclined plates arranged in parallel, and the sedimentation inclined plates are arranged at an angle with the inner wall of the first cylindrical barrel; and the inclined plate assembly is located in the middle and lower part of the first cylindrical barrel.

[0038] The application of the technical scheme of the present invention has the following beneficial effects: the sludge phosphorus release and phosphorus crystal recovery device of the present invention comprises a phosphorus release mechanism and a phosphorus crystal recovery mechanism, the phosphorus release mechanism comprises a sludge concentration unit, a sludge cracking component and a sludge dewatering unit, the sludge cracking component comprises a sludge cracking unit and a pH value regulating unit arranged in series, the phosphorus crystal recovery mechanism comprises a shell component, a liquid inlet pipe, a liquid discharge pipe, a discharge port, a plug flow stirring component, a folded plate vortex component, a modular vortex component, an inclined plate component and a micro-nano aeration disk, so as to realize low-cost and efficient phosphorus release and phosphorus crystal recovery of the whole amount of excess sludge. The principle is: the present invention adds alkali to crack 10% to 20% of the concentrated sludge, and then uses the COD (carbon source) released by the cracking as the carbon source of polyphosphate microorganisms (polyphosphate bacteria) in the whole amount of excess sludge entering the sludge concentration unit, and anaerobic phosphorus release occurs in the anaerobic environment of the sludge concentration unit without adding an external carbon source. The new scheme of a small amount of concentrated sludge alkali phosphorus explanation + anaerobic biological phosphorus release of the whole amount of excess sludge realizes low-cost and efficient phosphorus release of the whole amount of excess sludge. The phosphorus crystal recovery mechanism adopts an outer shell, a middle shell, and an inner shell to form a three-layer shell arrangement, forming a circulating flow channel formed by a first water flow ascending channel and a water flow descending channel and a second water flow ascending channel. The stirring blades and the folded plate vortex components in the plug flow stirring component are arranged in the first water flow ascending channel, and the modular vortex components are arranged in the water flow descending channel, forming a mechanical stirring mixed crystallization + hydraulic vortex crystallization composite system; the opening at the bottom end of the first water flow ascending channel is located in the crystal gathering area at the bottom of the outer shell and a micro-nano aeration disk is arranged below, so that the small particle crystals in the crystal gathering area can enter the water flow circulation channel as seeds with the circulation of water flow, providing a ready-made nucleation site for the solution, reducing the critical supersaturation required for the system to form new crystal nuclei, thereby reducing spontaneous nucleation (forming The probability of a large number of tiny crystals) can be reduced, and the formation of irregular dendrites or needle-shaped crystals can be suppressed, promoting the formation of denser, uniform prismatic or flaky large-particle crystals; due to its special structure, hydraulic classification is achieved during operation, so that the solution is fully mixed with materials and the crystal particles are fluidized, and self-induced crystallization is achieved without the addition of crystal seeds. The particle size of the crystal particles is larger than that of traditional stirred crystallization; the first water flow rising channel and the water flow descending channel form a circulating flow channel to automatically sort the crystal particles. The particles with large size and mass will automatically separate from the circulating water flow under the action of gravity and be discharged into the crystal gathering area. The crystal particles with small particle size and mass continue to crystallize in the water flow circulation channel. The crystal particles collected in the crystal gathering area are larger in size and higher in purity than those of traditional stirred crystallization, realizing efficient recovery of phosphorus. The inclined plate assembly is arranged in the second water flow rising channel, which can perform secondary separation on the fine crystal particles entrained in the water flow, further improving the recovery efficiency of phosphorus crystal particles.

[0039] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0041] Figure 1 It is a plan view of the sludge phosphorus release and phosphorus crystal recovery device in a preferred embodiment of the present invention;

[0042] Figure 2 yes Figure 1 Schematic diagram of the elevation structure;

[0043] Figure 3 yes Figure 2 Schematic diagram of the structure of the sludge cracking component;

[0044] Figure 4 yes Figure 2 Schematic diagram of the structure of the medium phosphorus crystal recovery mechanism;

[0045] Figure 5 yes Figure 4 A top view of the middle fold plate vortex assembly installed on the inner shell;

[0046] Figure 6 yes Figure 5 MM cross-section diagram;

[0047] Figure 7 yes Figure 4 A schematic diagram of the structure of the vortex monomer of the modular vortex assembly;

[0048] Figure 8 yes Figure 7 A top view of

[0049] Fig. 9 yes Figure 8 NN cross-section diagram;

[0050] Fig.10 This is a data chart of the particle size distribution detection of the crystal particles in the phosphorus crystal recovery mechanism.

[0051] Among them, 1. Sludge concentration unit, 1.1. Residual sludge inlet, 1.2. Concentrated sludge outlet, 1.3. Supernatant outlet; 2. Sludge breaking component, 2.1. Sludge breaking unit, A1. First shell, A1.1. First accommodating cavity, A1.2. First body, A1.3. Protrusion, A1.4. Removable cover plate, A2. First stirring component, A2.1. First driving power source, A2.2. First stirring shaft, A2.3. First stirring blade, A3. First mud inlet pipe, A4. First mud outlet pipe, A5. First dosing pipe, A6. First pH controller, A6.1. First measuring electrode, A7. , first odor collecting pipe; 2.2, pH value adjusting unit, B1, second shell, B1.1, second containing chamber, B1.2, second body, B2, second stirring assembly, B2.1, second driving power source, B2.2, second stirring shaft, B2.3, second stirring blade, B3, second mud inlet pipe, B4, second mud outlet pipe, B5, second dosing pipe, B6, second pH controller, B6.1, second measuring electrode, B7, second odor collecting pipe; 3, sludge dehydration unit; 4, first pipeline; 5, second pipeline; 6, third pipeline; 7, fourth pipeline; 8, phosphorus crystal recovery mechanism, 8.1, outer shell, 8 .1.1, first cylindrical cylinder, 8.1.2, first conical cylinder, 8.1.3, a accommodating chamber, 8.1.4, b accommodating chamber, 8.2, middle shell, 8.2.1, second cylindrical cylinder, 8.2.2, second conical cylinder, 8.2.3, c accommodating chamber, 8.2.4, d accommodating chamber, 8.3, inner shell, 8.3.1, third cylindrical cylinder, 8.3.2, e accommodating chamber, 8.3.3, third conical cylinder, 8.3.4, bottom cylindrical cylinder, 8.3.5, f accommodating chamber, 8.4, water collecting tank, 8.5, liquid inlet pipe, 8.6, liquid discharge pipe, 8.7, discharge port, 8.8, plug flow mixing group Components, 8.8.1, third driving power source, 8.8.2, third stirring shaft, 8.8.3, third stirring blade; 8.9, folded plate vortex assembly, 8.9.1, first folded plate, 8.9.2, second folded plate, 8.10, modular vortex assembly, 8.10.1, first vertical plate, 8.10.2, second vertical plate, 8.10.3, upper arc outer frame, 8.10.4, upper arc inner frame, 8.10.5, lower arc outer frame, 8.10.6, lower arc inner frame, Y, semicircular shell vortex sheet, S, isosceles right triangle vortex sheet; 8.11, inclined plate assembly; 8.12, micro-nano aeration disk; 8.13. Compressed air pipe; A. First water flow rising channel, B. Water flow falling channel, C. Second water flow rising channel, D. Crystal gathering area; 9. Fifth pipeline; 10. Dry mud conveying parts; 11. Sixth pipeline; 12. Residual sludge conveying pipeline; 13. Seventh pipeline; H. Pipeline mixer, H1. Magnesium salt dosing pipe, H2. Ammonium salt dosing pipe, H3. Alkali dosing pipe; F1. First electric valve, F2. Second electric valve; K1. First flowmeter, K2. Second flowmeter, K3. Third flowmeter, K4. Fourth flowmeter; C4. Lifting pump; P1. Orthophosphate online detector, P2. pH value online detector. . DETAILED DESCRIPTION

[0052] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0053] Example:

[0054] See also Figure 1-Figure 2 A sludge phosphorus release and phosphorus crystal recovery device includes a phosphorus release mechanism and a phosphorus crystal recovery mechanism 8. The phosphorus release mechanism is used to release phosphorus from the residual sludge of the urban sewage treatment plant, and then the phosphorus is recovered by the phosphorus crystal recovery mechanism 8.

[0055] In this embodiment, the phosphorus release mechanism includes a sludge concentration unit 1, a sludge breaking component 2 and a sludge dehydration unit 3. The sludge concentration unit 1 is provided with a residual sludge inlet 1.1, a concentrated sludge outlet 1.2 and a supernatant outlet 1.3. The residual sludge inlet 1.1 is connected to the residual sludge conveying pipeline 12, and the residual sludge conveying pipeline 12 is provided with a first flowmeter K1; the sludge breaking component 2 includes a sludge breaking unit 2.1 and a pH value adjustment unit 2.2 arranged in series. The residual sludge enters the sludge concentration unit 1 through the residual sludge conveying pipeline 12 and the residual sludge inlet 1.1 for concentration and phosphorus release treatment; the supernatant obtained after treatment is discharged through the supernatant outlet 1.3; the concentrated sludge obtained after treatment is discharged through the concentrated sludge outlet 1.2, and a part of the concentrated sludge enters the sludge cracking unit 2.1 through the first pipeline 4 (a second flowmeter K2 and a first electric valve F1 are provided on this pipeline) for sludge cracking treatment, and another part of the concentrated sludge enters the sludge dehydration unit 3 through the second pipeline 5 (a third flowmeter K3 and a second electric valve F2 are provided on this pipeline) for sludge dehydration treatment. The flow ratio of the sludge in the two pipelines can be adjusted by controlling the first electric valve F1 and the second electric valve F2; the cracked sludge after the cracking treatment enters the pH value adjustment unit 2.2 for pH value adjustment, and then is lifted by the lifting pump C4, and is transported to the residual sludge inlet 1.1 by the third pipeline 6 to circulate to the sludge concentration unit 1. The detailed structure is as follows:

[0056] The sludge concentration unit 1 adopts a circular gravity concentration tank in the prior art. In this embodiment, the tank body is constructed of reinforced concrete or steel anti-corrosion equipment. The concentration time of sludge in the tank (calculated by hydraulic retention time) is 14 to 24 hours. The residual sludge feed port 1.1 is connected to the residual sludge conveying pipeline 12, and the residual sludge conveying pipeline 12 is connected to the external sludge conveying pump. The sludge flows from the intersection of the residual sludge conveying pipeline 12 and the outlet pipeline of the lifting pump C4 (i.e., the third pipeline 6) to the residual sludge feed port 1.1 in the sludge concentration unit 1. The time is not less than 3 seconds; the supernatant discharge port 1.3 arranged at the top of the sludge concentration unit 1 is connected to the phosphorus crystal recovery mechanism 8, and the supernatant is transported to the phosphorus crystal recovery mechanism for phosphorus crystal recovery treatment; the bottom of the sludge concentration unit 1 is provided with a concentrated sludge discharge port 1.2, and the concentrated sludge discharge port 1.2 is respectively connected to the sludge cracking component 2 and the sludge dewatering unit 3.

[0057] The sludge decomposition component 2 includes a sludge decomposition unit 2.1 and a pH value adjustment unit 2.2 arranged in series, see Figure 3 , this embodiment is preferred:

[0058] The sludge decomposition unit 2.1 includes a first shell A1, a first stirring assembly A2, a first mud inlet pipe A3, a first mud outlet pipe A4 and a first pH controller A6; the first shell A1 includes a first body A1.2 having a first accommodating cavity A1.1, the first mud inlet pipe A3 and the first mud outlet pipe A4 are both arranged on the first body A1.2 and are both connected to the first accommodating cavity A1.1; the first body A1.2 is provided with a first dosing pipe A5 connected to the first accommodating cavity A1.1; the first stirring assembly A2 includes a first drive A power source A2.1, a first stirring shaft A2.2 and a first stirring blade A2.3, wherein the first driving power source A2.1 is arranged on the first shell A1; the connection end of the first stirring shaft A2.2 is connected to the output end of the first driving power source A2.1, the free end of the first stirring shaft A2.2 is arranged in the first accommodating chamber A1.1 and is provided with the first stirring blade A2.3; the first pipeline 4 is connected with the first mud inlet pipe A3, and the first mud outlet pipe A4 is connected with the pH value adjusting unit 2.2 through the fourth pipeline 7. A measuring hole connected with the first accommodating chamber A1.1 is arranged on the first body A1.2, and the first pH controller A6 is arranged at the measuring hole for measuring the pH value of the sludge; the first pH controller is connected to an external PLC control system, and the pH controller measures the pH value of the sludge through a first measuring electrode A6.1; the first measuring electrode is arranged at the measuring hole and a protective net is arranged on the outside of the first measuring electrode.

[0059] Further preferably, the first shell A1 is a cylindrical shell, made of carbon steel anti-corrosion material, and uses sodium hydroxide to break down sludge at normal temperature and pressure. In this embodiment, the pH control range of the sludge breaking component is: 10.8-11, and the reaction time of sludge breaking is: 40-60min. The inner wall of the first accommodating chamber A1.1 is also provided with a plurality of protrusions A1.3 facing the center of the first accommodating chamber; the protrusion A1.3 is a hemispherical protrusion with a radius of 40-80mm; the plurality of protrusions A1.3 are evenly distributed on the inner wall of the first accommodating chamber, where the radius of the hemispherical protrusions is the same, and the plurality of protrusions are evenly distributed on the vertical inner wall of the first accommodating chamber, and the distance between the edges of two adjacent protrusions is 1.5 times their diameters. The first stirring shaft A2.2 is provided with multiple layers of the first stirring blades A2.3 at intervals along its axial direction (here, preferably two layers of first stirring blades are arranged along the up and down directions, and the stirring blades generate upward thrust when rotating); the first body A1.2 is also provided with a first odor collecting pipe A7 for collecting odor generated in the first accommodating chamber; the first shell A1 also includes an opening connected to the first accommodating chamber A1.1, and a removable cover A1.4 is provided at the opening, and the first driving power source A2.1, the first dosing pipe A5, the first pH controller A6 and the first odor collecting pipe A7 are all arranged on the removable cover A1.4.

[0060] In this embodiment, the pH value adjusting unit 2.2 includes a second shell B1, a second stirring assembly B2, a second mud inlet pipe B3 and a second mud outlet pipe B4; the second shell B1 includes a second body B1.2 having a second accommodating chamber B1.1, the second mud inlet pipe B3 and the second mud outlet pipe B4 are both arranged on the second body B1.2 and are both connected to the second accommodating chamber B1.1; the second body B1.2 is provided with a second dosing pipe B5 connected to the second accommodating chamber B1.1; the second stirring assembly B2 includes a second driving power The second driving power source B2.1, the second stirring shaft B2.2 and the second stirring blade B2.3, the second driving power source B2.1 is arranged on the second shell B1; the connecting end of the second stirring shaft B2.2 is connected to the output end of the second driving power source B2.1, the free end of the second stirring shaft B2.2 is arranged in the second accommodating cavity B1.1 and the second stirring blade B2.3 is arranged thereon; the fourth pipeline 7 is connected to the second mud inlet pipe B3, the second mud outlet pipe B4 is connected to the third pipeline 6, and the lifting pump C4 is installed on the third pipeline 6. Further preferably, the second shell B1 is a cylindrical shell; the control range of the pH value in the pH value adjusting unit 2.2 in this embodiment is: 9 to 9.5. The effective volume of the second accommodating chamber B1.1 in the pH value adjusting unit 2.2 is half of the volume of the first accommodating chamber A1.1 in the sludge decomposition unit 2.1, and the height of the pH value adjusting unit 2.2 is lower than the sludge decomposition unit 2.1, which can ensure that the sludge in the sludge decomposition unit 2.1 flows into the pH value adjusting unit 2.2 by gravity. The soluble COD of the sludge discharged from the third pipeline 6 is not less than 2000 mg / L, and the pH is 9-9.5. In addition, the second body B1.2 is provided with a measuring hole connected to the second accommodating chamber B1.1, and the second pH controller B6 is arranged at the measuring hole for measuring the pH value of the sludge; the second pH controller is connected to the external PLC control system, and the pH controller measures the pH value of the sludge through the second measuring electrode B6.1; the second measuring electrode is arranged at the measuring hole and a protective net is arranged on the outside of the second measuring electrode. The second body B1.2 is also provided with a second odor collection pipe B7 for collecting the odor generated in the second accommodating chamber.

[0061] In this embodiment, the phosphorus crystal recovery mechanism 8 is connected to the supernatant discharge port 1.3 through a fifth pipeline 9 (a fourth flowmeter K4 is provided on the pipeline); the sludge after sludge dehydration treatment by the sludge dehydration unit 3 is transported through a dry sludge conveying member 10 (a dry sludge conveying pipe is preferred here, and a conveying device such as a conveying belt can also be used), and the sludge dehydrated liquid after sludge dehydration treatment is connected to the fifth pipeline 9 or the phosphorus crystal recovery mechanism through a sixth pipeline 11. Figure 1-2 It is shown in the figure that it enters the phosphorus crystal recovery mechanism 8 after being connected with the fifth pipeline 9.

[0062] Further preferably, the phosphorus crystal recovery mechanism 8 includes a shell assembly, a liquid inlet pipe 8.5, a liquid discharge pipe 8.6, a discharge port 8.7, a plug flow stirring assembly 8.8, a folded plate vortex assembly 8.9, a modular vortex assembly 8.10, an inclined plate assembly 8.11 and a micro-nano aeration disk 8.12 (the right line in the figure is an air pipe connected to the micro-nano aeration disk, which is not marked), and the shell assembly includes an outer shell 8.1, a middle shell 8.2 and an inner shell 8.3 which are sequentially sleeved from the outside to the inside, see Figure 4 , the structure is as follows:

[0063] The upper end of the outer shell 8.1 is provided with a detachable cover plate for sealing, the lower end of the outer shell 8.1 is a closed end, and the outer shell 8.1 comprises a first cylindrical cylinder 8.1.1 and a first conical cylinder 8.1.2 which is wide at the top and narrow at the bottom and arranged in series from top to bottom, an a accommodating chamber 8.1.3 is arranged in the first cylindrical cylinder 8.1.1, and a b accommodating chamber 8.1.4 which is communicated with the a accommodating chamber 8.1.3 is arranged in the first conical cylinder 8.1.2, and the discharge port 8.7 is externally connected to a compressed air pipe 8.13 (when the discharge port 8.7 is blocked, the crystals can be blown out of the discharge port through the compressed air pipe 8.13 to clear the discharge port), and the discharge port 8.7 is communicated with the b accommodating chamber 8.1.4, Figure 4 Specifically, the lower part of the b accommodating chamber 8.1.4 forms a crystal gathering area D, and the discharge port 8.7 is connected to the crystal gathering area D; the upper part of the a accommodating chamber 8.1.3 is provided with a water collecting tank 8.4.

[0064] The middle shell 8.2 has openings at both the upper and lower ends and is disposed in the first cylindrical barrel 8.1.1. The middle shell 8.2 comprises a second cylindrical barrel 8.2.1 and a second conical barrel 8.2.2 which is wide at the top and narrow at the bottom and arranged in series from top to bottom. A c accommodating chamber 8.2.3 is disposed in the second cylindrical barrel 8.2.1, and a d accommodating chamber 8.2.4 which is communicated with the c accommodating chamber 8.2.3 is disposed in the second conical barrel 8.2.2. The upper end of the second conical barrel 8.2.2 is located in the a accommodating chamber 8.1.3 and the lower end thereof is located in the b accommodating chamber 8.1.4.

[0065] The upper and lower ends of the inner shell 8.3 are both provided with openings. The inner shell 8.3 includes a third cylindrical barrel 8.3.1, a third conical barrel 8.3.3 and a bottom cylindrical barrel 8.3.4. The third cylindrical barrel 8.3.1 includes an e accommodating chamber 8.3.2 with openings at both ends, and the upper end surface of the third cylindrical barrel 8.3.1 is lower than the upper end surface of the second cylindrical barrel 8.2.1; the third conical barrel 8.3.3 and the bottom cylindrical barrel 8.3.4 are provided with an f accommodating chamber 8.3.5 connected to the e accommodating chamber 8.3.2; the lower end of the bottom cylindrical barrel 8.3.4 is located outside the middle shell 8.2 and inside the first conical barrel 8.1.2. A micro-nano aeration plate 8.12 (this device is a prior art and can be purchased directly) connected to an external blower is arranged 0.2 to 0.3 meters below the bottom end of the bottom columnar cylinder 8.3.4.

[0066] In the phosphorus crystal recovery mechanism 8: the e accommodating chamber 8.3.2 and the f accommodating chamber 8.3.5 form a first water flow ascending channel A; the inner wall of the second columnar barrel 8.2.1 and the outer wall of the third columnar barrel 8.3.1 form a water flow descending channel B; the annular area between the inner wall of the outer shell 8.1 (i.e. the inner wall of the first columnar barrel 8.1.1 and the inner wall of the first conical barrel 8.1.2 together) and the outer wall of the middle shell 8.2 (i.e. the outer wall of the second columnar barrel 8.2.1 and the outer wall of the second conical barrel 8.2.2 together) and the water collecting tank 8.4 located at the upper part of the a accommodating chamber 8.1.3 enclose a second water flow ascending channel C; the plug flow stirring The mixing assembly 8.8 is arranged on a detachable cover plate located at the upper end of the outer shell 8.1, and the mixing blades in the plug-flow mixing assembly 8.8 and the folded plate vortex assembly 8.9 are arranged in the first water flow rising channel A along the up and down direction; the modular vortex assembly 8.10 is arranged in the water flow descending channel B; the inclined plate assembly 8.11 is arranged in the second water flow rising channel C; the liquid inlet pipe 8.5 passes through the side wall of the first columnar barrel 8.1.1 and the side wall of the second columnar barrel 8.2.1 and is inserted into the upper part of the first water flow rising channel A, and the water outlet end of the liquid inlet pipe 8.5 is lower than the position of the water collecting tank 8.4; the discharge pipe 8.6 is connected to the water collecting tank 8.4.

[0067] Further preferably, the plug-flow stirring assembly 8.8 includes a third driving power source 8.8.1, a third stirring shaft 8.8.2 and a third stirring blade 8.8.3, wherein the third driving power source 8.8.1 is fixedly arranged on a detachable cover plate located at the upper end of the outer shell 8.1, the connecting end of the third stirring shaft 8.8.2 is connected to the output end of the third driving power source 8.8.1, the free end of the third stirring shaft 8.8.2 penetrates the detachable cover plate and extends into the interior of the third columnar barrel 8.3.1, and the third stirring blade 8.8.3 is arranged on the free end of the third stirring shaft 8.8.2; the outlet end of the liquid inlet pipe 8.5 is located 20-50cm above the third stirring blade 8.8.3. The plug-flow stirring assembly 8.8 lifts the liquid and suspended particles in the first water flow rising channel A from its lower section to the upper section, and provides a driving force for the water flow to circulate in the first water flow rising channel A.

[0068] The top of the folded plate vortex component 8.9 is 0.5m away from the lower edge of the plug flow stirring component 8.8 and the lower end is flush with the lower end of the inner shell 8.3; see Figure 5 and Figure 6 The folded plate vortex assembly 8.9 includes a first folded plate 8.9.1 and a second folded plate 8.9.2 arranged in parallel. The first folded plate 8.9.1 includes a plurality of connecting plates connected in sequence, and the angle α between two adjacent connecting plates is 80°-100°; the first folded plate 8.9.1 and the second folded plate 8.9.2 are mirror images. The angle α between adjacent connecting plates in the folded plate vortex assembly is 90°, and the length Q1 of the connecting plate is 20% of the diameter of the inner shell 8.3. The angle and length of each connecting plate in the same first folded plate or second folded plate are the same, and the crests and troughs of the first folded plate and the second folded plate are horizontally aligned, and the horizontal spacing Q2 is equal and is 10% of the diameter of the inner shell 8.3.

[0069] The upper end of the modular vortex component 8.10 is located 0.5m below the inner cavity liquid level of the water flow descending channel B, and the lower end is 0.6m away from the plane where the lower end of the inner shell 8.3 is located. Figure 7 , Figure 8 , Fig. 9As shown, the modular eddy current assembly has an outer shape of a fan ring cylindrical cube, and its horizontal projection is a fan ring shape, including a plurality of eddy current monomers stacked or spaced, and the eddy current monomer is a hollow columnar body surrounded by a first vertical plate 8.10.1, a second vertical plate 8.10.2, an upper arc-shaped outer frame 8.10.3, an upper arc-shaped inner frame 8.10.4, a lower arc-shaped outer frame 8.10.5, and a lower arc-shaped inner frame 8.10.6, and a eddy current sheet is installed in the eddy current monomer, and the cross section of the eddy current sheet is at least one of a triangle, a semicircle, and a rectangle. The columnar body is made of metal or engineering plastic material, and can bear the weight of the frame itself and the eddy current sheet installed inside.

[0070] In this embodiment, it is further preferred that the vortex monomer is provided with a semicircular shell vortex layer and an isosceles right-angled triangle vortex layer alternately formed, the projection of the semicircular shell vortex layer in the horizontal direction is an arc shape, and its cross-sectional shape is a semicircle with a diameter of 30 to 40 mm. The horizontal spacing of each semicircular shell vortex sheet Y in the same layer is equal, and the distance between two adjacent semicircular shell vortex sheets is 1.3 times its diameter; the length of the isosceles right-angled triangle vortex sheet S in the same layer is determined by the radius of its own horizontal projection arc and the arc radian corresponding to the horizontal projection of the frame of the vortex monomer, and the projection of a single isosceles right-angled triangle vortex sheet in the horizontal direction is an arc shape, and its cross-sectional shape is an isosceles right-angled triangle, and the height of the triangle is the same as the radius of the semicircular shell vortex sheet. Two adjacent layers of semicircular shell vortex sheets and isosceles right-angled triangle vortex sheets are arranged alternately, and the projections of two adjacent layers of semicircular shell vortex sheets and isosceles right-angled triangle vortex sheets on the horizontal plane do not overlap.

[0071] The inclined plate assembly 8.11 comprises a plurality of sedimentation inclined plates arranged in parallel, and the sedimentation inclined plates are arranged at an angle with the inner wall of the a accommodation cavity in the first cylindrical barrel 8.1.1; and the inclined plate assembly 8.11 is located in the middle and lower part of the a accommodation cavity in the first cylindrical barrel 8.1.1.

[0072] The liquid inlet pipe 8.5 includes a horizontal pipe section, an arc-shaped transition pipe section and a vertical pipe section arranged in series, the horizontal pipe section passes through the upper part of the outer shell 8.1 and the middle shell 8.2, the arc-shaped transition pipe section is a pipe section bent downward by 90 degrees and extends to the upper part of the inner shell 8.3, and the outlet of the vertical pipe section is located 0.4 meters above the third stirring blade 8.8.3 in the plug-flow stirring assembly 8.8. A pipeline mixer H is installed on the horizontal pipe section of the liquid inlet pipe 8.5, and the pipeline mixer H is connected with the magnesium salt dosing pipe H1, the ammonium salt dosing pipe H2 and the alkali dosing pipe H3, and the supernatant, sludge dewatering liquid, magnesium salt, ammonium salt and alkali are mixed evenly and then enter the phosphorus crystal recovery mechanism 8.

[0073] In this embodiment, the sludge dewatering unit 3 adopts the existing horizontal spiral centrifugal dewatering equipment, the sludge inlet pipe is connected to the second pipeline 5, and the sludge dewatering liquid discharge pipe is connected to the phosphorus crystal recovery mechanism 8; in this embodiment, during the sludge dewatering process, no lime, iron salt, aluminum salt or other reagents that can form precipitates with phosphate ions are added, and only a small amount of polyacrylamide reagent is added as needed. The dewatered sludge discharged after sludge dehydration is transported out for disposal.

[0074] In addition, a control system is also provided in this embodiment, which includes online detection instruments, cables and an electric control cabinet containing a programmable logic controller (PLC). The online detection instruments include a first flow meter K1 arranged on the residual sludge conveying pipeline 12, a second flow meter K2 arranged on the first pipeline 4, a third flow meter K3 arranged on the second pipeline 5, a fourth flow meter K4 arranged on the fifth pipeline 9, an orthophosphate online detector P1 arranged near the supernatant discharge pipe, an online pH value detector P2 arranged in the phosphorus crystal recovery mechanism 8, and a first pH controller A6 and a second pH controller B6 arranged in the sludge decomposition component; the cables and the electric control cabinet containing the programmable logic controller (PLC) all adopt existing mature equipment, which can power the online detection instruments and communicate with the online detection instruments. The PLC controls the operation of external dosing equipment and other equipment according to the data detected by the online detection instruments and the preset control logic.

[0075] The technical solution of this embodiment is specifically:

[0076] The phosphorus-rich residual sludge (Q residual, water content 99.2%) discharged from the sewage treatment biochemical system is mixed with the post-destruction sludge (Q post-destruction) discharged from the sludge destructing unit 2 through the residual sludge conveying pipeline 12 and then enters the sludge concentration unit 1. The phosphorus-rich residual sludge is concentrated in the sludge concentration unit 1 under the action of the carbon source provided by the post-destruction sludge and simultaneously undergoes anaerobic biological phosphorus release effect, releasing phosphorus in the solid phase into the liquid phase. The low-phosphorus sludge after concentration and biological phosphorus release is discharged from the bottom of the gravity concentration tank. A part of the concentrated sludge (Q destruction) enters the sludge destructing unit 2.1 in the sludge destructing component 2 through the first pipeline 4 for sludge destructing. The sludge after destructing (Q post-destruction) enters the pH value adjustment unit 2.2 for pH adjustment and then returns to the sludge concentration unit 1; the other part of the concentrated sludge (Q dewatered) is discharged into the sludge dewatering unit 3 through the second pipeline 5 for dewatering. In this embodiment, the flow rate or mass ratio Q cracking of the sludge entering the sludge cracking unit and the total amount of sludge after concentration is: (Q cracking + Q dehydration) = 0.2; the high-concentration phosphorus-containing supernatant produced by the sludge concentration unit 1 is discharged into the phosphorus crystal recovery mechanism 8 through the fifth pipeline 9 to recover phosphorus; the sludge dehydration liquid produced by the sludge dehydration unit is mixed with the supernatant of the sludge concentration unit through the sixth pipeline 11 and discharged together into the phosphorus crystal recovery mechanism 8 for phosphorus crystal recovery, and the dry sludge is transported out for disposal through the dry sludge conveying part 10; the low-phosphorus water discharged from the phosphorus crystal recovery mechanism is returned to the biochemical pool at the front end of the sewage treatment system through the seventh pipeline 13.

[0077] In this embodiment, after the sludge is cracked by alkali, COD (carbon source), ammonia nitrogen, organic nitrogen, orthophosphate, organic phosphorus and other substances are released into the water phase and converted into cracked sludge (Q after cracking). The test data of the main components of the sludge before concentration (Q residual) and after cracking (Q after cracking) are shown in Table 1. The mass of the cracked sludge (Q after cracking) is equal to the mass of the concentrated sludge (Q cracked) plus the mass of the alkali and acid agents added during the cracking process. The cracked sludge (Q after cracking) is discharged into the water inlet of the gravity thickening tank.

[0078] Table 1 Main components of sludge before and after sludge concentration

[0079]

[0080] Note: In the table, the concentration of sludge before concentration (Qresidual, referring to the residual sludge entering the sludge concentration unit through the residual sludge conveying pipeline 12) is MLSS=8g / L, and the concentration of sludge after concentration and decomposition (Qdecomposition) is MLSS=20g / L. In this embodiment, the volume of sludge after concentration and decomposition (Qdecomposition) is only about 8% of the volume of residual sludge Qresidual entering the sludge concentration tank through the residual sludge conveying pipeline 12. The composition data of the sludge are all measured by centrifuging the sludge and taking the supernatant.

[0081] The sludge cracking step in this embodiment achieves five technical effects at the same time:

[0082] ① The residual phosphorus in the sludge was separated by sludge breaking, and orthophosphate was released from the solid phase to the liquid phase, creating conditions for the subsequent phosphorus crystallization recovery mechanism to recover phosphorus;

[0083] ② The high-concentration COD (carbon source) released by sludge cracking is returned to the sludge thickening tank as a carbon source for anaerobic biological phosphorus release of the remaining sludge. No external carbon source is needed, which realizes "waste treatment with waste" and saves the cost of sludge phosphorus release;

[0084] ③ Sludge cracking releases ammonia nitrogen, which reduces the amount of ammonium salt (such as ammonium chloride) added by the subsequent phosphorus crystal recovery mechanism to recover struvite, further saving the cost of phosphorus crystal recovery;

[0085] ④ After the sludge is cracked, the dewatering performance can be improved, and the amount of sludge dewatering agent added in the subsequent sludge dewatering unit can be reduced, which is beneficial to improving the treatment efficiency of the subsequent sludge dewatering unit and reducing the cost of sludge dewatering;

[0086] ⑤ The pH of the cracked sludge is adjusted to 9-9.5 by adding acid in the pH adjustment unit 2.2, and after being mixed with the residual sludge (Q residual), in this scheme, the pH of the mixed sludge entering the sludge thickening tank can be between 8 and 8.5, forming a suitable pH condition for anaerobic biological phosphorus release in the sludge thickening tank.

[0087] The excess sludge before concentration (Q excess) and the sludge after cracking (Q cracked) are mixed before entering the sludge concentration unit 1 and then enter the sludge concentration unit 1. Compared with the conventional gravity concentration process, this embodiment not only realizes the physical concentration of sludge in the sludge concentration unit 1, but also realizes the following technical effects:

[0088] ① The excess sludge (Q excess) and the cracked sludge (Q cracked) are mixed before entering the sludge concentration unit. The mixing process and pipeline transportation process can enable the microorganisms in the excess sludge (Q excess) to quickly adsorb the organic components in the cracked sludge (Q cracked), creating conditions for the microorganisms to further absorb the adsorbed organic matter (carbon source) into the microbial cells in the concentration tank, overcoming the defects of low mass transfer and absorption efficiency between organic matter and microbial cells due to small fluid disturbance in the sludge concentration tank, and allowing more organic components in the cracked sludge to enter the microbial cells in the excess sludge to achieve anaerobic phosphorus release;

[0089] ② Phosphorus-rich microorganisms (such as polyphosphate bacteria) in the residual sludge release the phosphorus in the cells into the water (in the form of orthophosphate, PO4) under the action of COD (carbon source) provided by the decomposition sludge under the anaerobic conditions in the sludge concentration unit 1. 3-The anaerobic biological phosphorus release of the entire amount of excess sludge was achieved, and the orthophosphate (PO4 3- The concentration of phosphorus can reach 50-60 mg / L, which creates conditions for subsequent phosphorus crystal recovery;

[0090] ③ The organic nitrogen and organic phosphorus contained in the sludge are converted into ammonia nitrogen and orthophosphate (PO4 3- ), the conversion of organic nitrogen into ammonia nitrogen can save the dosage of ammonia nitrogen reagents for the subsequent phosphorus crystallization recovery mechanism, and the conversion of organic phosphorus into orthophosphate can further improve the phosphorus recovery efficiency (organic phosphorus cannot be recovered through struvite crystallization). This embodiment has a significant effect on sludge phosphorus release, and most of the phosphorus exists in the form of orthophosphate, which can be recovered by the subsequent phosphorus crystallization recovery mechanism 8.

[0091] The phosphorus crystal recovery mechanism 8 described in this embodiment uses magnesium ammonium phosphate crystals (struvite) to recover phosphorus in the liquid phase. The wastewater containing orthophosphate from the sludge concentration unit 1 and the sludge dehydration unit 3 is mixed with the reagent (the reagent is magnesium chloride, ammonium chloride, and sodium hydroxide) in the pipeline mixer H and then enters the phosphorus crystal recovery mechanism 8. The dosage of magnesium chloride and ammonium chloride reagents is based on Mg:NH4 + :P=1.3:1.3:1 (molar ratio), the pH of the crystallization reaction is controlled at 9.5~10, the third stirring blade rotates to generate an upward thrust, stirs and mixes the liquid and suspended particles, and makes the liquid mixture circulate. The micro-nano aeration disk aerates, releases a large number of micro-bubbles to disturb some fine crystal particles in the crystal aggregation area, so that some fine crystals in the crystal aggregation area enter the water circulation channel for circulation, and at the same time, the micro-bubbles increase the pH value of the solution by blowing off CO2, maintain an alkaline environment, and promote the formation of struvite crystals.

[0092] The orthophosphate in the influent water and the crystal-forming ions (magnesium ions, ammonium ions) in the reagent contact the magnesium ammonium phosphate crystals (crystal nuclei) from the crystal aggregation area D under the mechanical stirring of the third stirring blade and the microbubble stirring conditions, and circulate with the water flow in the first water flow ascending channel A, the water flow descending channel B and the crystal aggregation area D. When passing through the folded plate vortex component 8.9 and the modular vortex component 8.10, under the action of a large number of micro-vortices generated by the vortex component, the crystal-forming ions in the liquid mixture are further contacted and mixed with the crystal nuclei, and the tiny crystal particles are fluidized. The tiny crystals and the crystal nuclei and the crystal-forming ions are mixed in the micro-vortices. Under the action of the water, the water particles collide and contact fully, and self-induced crystallization is achieved without adding crystal seeds. The particle size of the crystal particles gradually increases. When the particle size and mass of the crystal particles increase to a certain extent, under the action of gravity, the large-particle crystals gradually separate from the circulating water flow and flow into the crystal gathering area D. After the crystallization is completed, the water flow enters the annular solid-liquid separation area. The fine crystal particles entrained in the water flow are further separated from the solid and liquid under the action of gravity and the inclined plate assembly. After the crystal particles are precipitated, they slide to the crystal gathering area D under the action of gravity. The supernatant after precipitation is collected upward to the water collection tank 8.4 and discharged from the phosphorus crystal recovery mechanism 8 through the drainage pipe 8.6. The struvite crystals accumulated in the crystal gathering area D are regularly discharged to the dehydration and separation equipment set separately through the discharge port 8.7. The compressed air is externally connected below the discharge port to disperse the crystals when the discharge port is blocked. In this embodiment, the recovery rate of the phosphorus crystal recovery mechanism for orthophosphate is greater than 85%, as shown in Table 2, and the recovered product is struvite.

[0093] Table 2 Comparison of the recovery of orthophosphate by the phosphorus crystal recovery mechanism of this embodiment with the prior art

[0094]

[0095] Note: The particle size distribution test data of phosphorus crystal particles in the phosphorus crystal recovery mechanism of this embodiment is detailed in the attached Fig.10 .

[0096] The low-phosphorus liquid discharged from the phosphorus crystal recovery mechanism is returned to the biochemical pool at the front end of the sewage treatment system through the seventh pipeline 13.

[0097] Applying the technical solution of this embodiment has the following beneficial effects:

[0098] 1. Existing sludge decomposition and phosphorus release technologies all use the method of decomposing the entire amount of excess sludge. In this embodiment, only 10% to 20% of the concentrated sludge needs to be decomposed by adding alkali, and the COD (carbon source) released by the decomposition is used as the carbon source for polyphosphate microorganisms (polyphosphate bacteria) in the entire amount of excess sludge entering the thickening tank. Anaerobic phosphorus release occurs in the anaerobic environment of the sludge thickening tank without the need for an external carbon source. The new scheme of alkaline phosphorus release of a small amount of concentrated sludge + anaerobic biological phosphorus release of the entire amount of excess sludge achieves low-cost and efficient phosphorus release from the entire amount of excess sludge. In this embodiment, the equipment investment and operating costs (drug consumption, electricity consumption) of the sludge breakdown unit are only equivalent to 10% to 20% of the existing full-volume sludge alkaline phosphorus decomposition process, and the equipment footprint can also be saved; the addition of carbon source to the cracked sludge shortens the anaerobic biological phosphorus release time of the sludge in the gravity thickening tank to 6 hours, which is only 1 / 80 of the time required for the traditional sludge anaerobic digestion process (anaerobic digestion time 20 to 30 days), greatly reducing the equipment investment and operating costs of sludge phosphorus release and phosphorus crystallization recovery.

[0099] 2. Some of the phosphorus and nitrogen elements released into the liquid phase by the existing physical dephosphorization (ultrasound, thermal hydrolysis, mechanical ball milling) and chemical dephosphorization (acid, alkali) technologies exist in the form of organic phosphorus and organic nitrogen, and organic phosphorus is difficult to recycle. In this embodiment, the sludge after chemical dephosphorization is returned to the concentration tank. The organic phosphorus and organic nitrogen released during the dephosphorization process are converted into orthophosphate and ammonia nitrogen that can be recovered by the subsequent phosphorus crystallization recovery unit under the action of the anaerobic environment of the concentration tank and anaerobic bacteria in the remaining sludge, thereby further improving the phosphorus recovery rate and reducing the cost of adding ammonia nitrogen to the phosphorus crystallization recovery unit.

[0100] 3. At present, most of the domestic urban sewage treatment plants adopt the technical route of sludge gravity concentration + sludge dewatering for the treatment of residual sludge, and have built sludge concentration tanks and sludge dewatering facilities. In this embodiment, the gravity concentration tank adopts the existing conventional gravity concentration tank. When it is necessary to recover phosphorus from the residual sludge of the existing sewage treatment plant, it is only necessary to add a sludge breaking component (only 10% to 20% of the total concentrated sludge needs to be broken, and there is no need to break the entire amount of concentrated sludge), a sludge phosphorus crystallization recovery device, and a control system. The pipelines are modified accordingly to economically and conveniently realize the recovery of sludge phosphorus resources in the existing sewage treatment plants.

[0101] 4. In this embodiment, the phosphorus crystallization recovery mechanism adopts an outer shell, a middle shell, and an inner shell to form a three-layer shell arrangement, forming a circulating flow channel formed by a first water flow rising channel and a water flow descending channel and a second water flow rising channel. The plug flow stirring component and the folded plate vortex component are arranged from top to bottom in the first water flow rising channel, and the modular vortex component is arranged in the water flow descending channel, forming a mechanical stirring mixed crystallization + hydraulic vortex crystallization composite system; the opening at the bottom end of the first water flow rising channel is located in the crystal gathering area at the bottom of the outer shell and a micro-nano aeration disk is arranged below, so that the small particle crystals in the crystal gathering area can be more used as seeds to enter the water flow circulation channel with the circulation of the water flow under the disturbance of micro-nano bubbles. The interface effect of the micro-nano bubbles and the small particle seeds entrained in the water flow provide ready-made nuclei for the solution. The invention discloses a novel method for preparing a crystal particle by using a plurality of crystal structures of phosphorus atom in the water flow circulation channel. The crystal particles of phosphorus atom in the water flow circulation channel are arranged in a plurality of channels, and the plurality of channels are connected to each other. The crystal particles of phosphorus atom in the water flow circulation channel are arranged in a plurality of channels, and the plurality of channels are connected to each other. The crystal particles of phosphorus atom in the water flow circulation channel are arranged in a plurality of channels, and the plurality of channels are connected to each other. The crystal particles of phosphorus atom in the water flow circulation channel are arranged in a plurality of channels, and the plurality of channels are connected to each other. The plurality of channels are connected to each other by a plurality of channels, and the plurality of channels are connected to each other. The plurality of channels are connected to each other by a plurality of channels, and the plurality of channels are connected to each other.

[0102] 5. The optimal pH range for struvite crystallization is usually 9.0-11.0. The micro-nano bubbles released by the micro-nano aeration plate below the first water flow rising channel in the phosphorus crystallization recovery mechanism can increase the pH value of the solution by blowing off CO2, which can effectively remove CO2 dissolved in the water, reduce the impact of acidic substances, maintain an alkaline environment, promote the formation of struvite crystals, and improve the recovery efficiency of phosphorus. Blowing off CO2 to increase the pH value of the solution can also reduce the amount of alkali added from the outside and save the cost of reagents.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A sludge phosphorus release and phosphorus crystal recovery device, characterized in that: It includes a phosphorus releasing mechanism and a phosphorus crystal recovery mechanism (8); The phosphorus release mechanism comprises a sludge concentration unit (1), a sludge decomposition component (2) and a sludge dehydration unit (3); the sludge concentration unit (1) is provided with a residual sludge inlet (1.1), a concentrated sludge outlet (1.2) and a supernatant outlet (1.3); the sludge decomposition component (2) comprises a sludge decomposition unit (2.1) and a pH value adjustment unit (2.2) which are arranged in series; The phosphorus crystal recovery mechanism (8) comprises a shell assembly, a liquid inlet pipe (8.5), a liquid discharge pipe (8.6), a discharge port (8.7), a plug flow stirring assembly (8.8), a folded plate vortex assembly (8.9), a modular vortex assembly (8.10), an inclined plate assembly (8.11) and a micro-nano aeration disk (8.12), wherein the shell assembly comprises an outer shell (8.1), a middle shell (8.2) and an inner shell (8.3) which are sequentially sleeved from the outside to the inside; a detachable cover plate is provided at the upper end of the outer shell (8.1) for sealing, and a closed end is provided at the lower end of the outer shell (8.1), and the outer shell (8.1) comprises a first columnar barrel (8.1.1) and a second columnar barrel (8.2.3) which are serially arranged from top to bottom. a conical cylinder (8.1.2); the upper and lower ends of the middle shell (8.2) are both provided with openings and the middle shell is arranged in the first cylindrical cylinder (8.1.1), and the middle shell (8.2) comprises a second cylindrical cylinder (8.2.1) and a second conical cylinder (8.2.2) arranged in series from top to bottom; the upper and lower ends of the inner shell (8.3) are both provided with openings, and the inner shell comprises a third cylindrical cylinder (8.3.1), a third conical cylinder (8.3.3) and a bottom cylindrical cylinder (8.3.4) arranged in series from top to bottom, and the lower end of the bottom cylindrical cylinder (8.3.4) is located outside the middle shell (8.2) and inside the first conical cylinder (8.1.2); the third cylindrical cylinder (8.3.1) and the third conical cylinder (8.3.3) are arranged in series from top to bottom. The inner cavities of the three bodies (8.3.1), the third conical cylinder (8.3.3) and the bottom columnar cylinder (8.3.4) are connected to form a first water flow ascending channel (A); the inner wall of the middle shell (8.2) and the outer wall of the inner shell (8.3) form a water flow descending channel (B); the inner wall of the outer shell (8.1) and the outer wall of the middle shell (8.2) form a second water flow ascending channel (C); the lower inner cavity of the first conical cylinder (8.1.2) forms a crystal gathering area (D); the plug-flow stirring assembly (8.8) is arranged on a detachable cover plate located at the upper end of the outer shell (8.1); the stirring blades and the folding plate vortex in the plug-flow stirring assembly (8.8) are arranged on the upper end of the outer shell (8.1); The flow component (8.9) is arranged in the first water flow ascending channel (A) along the up-down direction, the liquid inlet pipe (8.5) is connected to the third columnar barrel (8.3.1) and the lower end of the liquid inlet pipe is located above the stirring blade in the plug flow stirring component (8.8); the modular vortex component (8.10) is arranged in the water flow descending channel (B); the inclined plate component (8.11) is arranged in the second water flow ascending channel (C), and the discharge port (8.7) is connected to the crystal gathering area (D); the micro-nano aeration plate (8.12) is located at the upper part of the crystal gathering area (D) and directly below the bottom columnar barrel (8.3.4); the discharge pipe (8.6) is connected to the second water flow ascending channel (C); The residual sludge enters the sludge concentration unit (1) through the residual sludge feed port (1.1) for treatment; the supernatant obtained after the treatment enters the phosphorus crystal recovery mechanism (8) through the supernatant discharge port (1.3) and the liquid inlet pipe (8.5); the concentrated sludge obtained after the treatment is discharged through the concentrated sludge discharge port (1.2), a part of the concentrated sludge enters the sludge decomposition unit (2.1) through the first pipeline (4) for sludge decomposition treatment, and another part of the concentrated sludge enters the sludge dehydration unit (3) through the second pipeline (5) for sludge dehydration treatment, and the sludge dehydrated liquid after the sludge dehydration treatment enters the phosphorus crystal recovery mechanism (8) through the liquid inlet pipe (8.5); the decomposition sludge after the decomposition treatment enters the pH value adjustment unit (2.2) for pH value adjustment, and then is transported to the residual sludge feed port (1.1) through the third pipeline (6) to circulate to the sludge concentration unit (1).

2. The sludge phosphorus release and phosphorus crystal recovery device according to claim 1, characterized in that: The sludge concentration unit is a gravity concentration tank; the ratio of the mass or flow rate of the sludge entering the sludge decomposition unit (2.1) through the first pipeline (4) for sludge decomposition treatment to the concentrated sludge discharged from the concentrated sludge discharge port (1.2) is 0.1 to 0.2; The control range of the pH value in the sludge decomposition unit (2.1) is 10.8 to 11.5; the control range of the pH value in the pH value adjustment unit (2.2) is 9 to 10; After the sludge whose pH value has been adjusted by the pH adjusting unit (2.2) intersects with the residual sludge conveying pipeline (12) through the third pipeline (6), the flow time of the mixed sludge from the intersection point to the outlet of the residual sludge feed inlet (1.1) is not less than 3 seconds.

3. The sludge phosphorus release and phosphorus crystal recovery device according to claim 1, characterized in that: The sludge decomposition unit (2.1) comprises a first shell (A1), a first stirring assembly (A2), a first sludge inlet pipe (A3) and a first sludge outlet pipe (A4); The first shell (A1) comprises a first body (A1.2) having a first accommodating cavity (A1.1); the first mud inlet pipe (A3) and the first mud outlet pipe (A4) are both arranged on the first body (A1.2) and are both connected to the first accommodating cavity (A1.1); The first body (A1.2) is provided with a first drug adding pipe (A5) which is in communication with the first containing cavity (A1.1); The first stirring component (A2) comprises a first driving power source (A2.1), a first stirring shaft (A2.2) and a first stirring blade (A2.3); the first driving power source (A2.1) is arranged on the first shell (A1); the connecting end of the first stirring shaft (A2.2) is connected to the output end of the first driving power source (A2.1); the free end of the first stirring shaft (A2.2) is arranged in the first accommodating cavity (A1.1) and the first stirring blade (A2.3) is arranged on the free end; The first pipeline (4) is in communication with the first mud inlet pipe (A3), and the first mud outlet pipe (A4) is in communication with the pH value adjustment unit (2.2) via a fourth pipeline (7).

4. The sludge phosphorus release and phosphorus crystal recovery device according to claim 3 is characterized in that: It also includes a first pH controller (A6); a measuring hole connected to the first containing cavity (A1.1) is provided on the first body (A1.2); the first pH controller is arranged at the measuring hole for measuring the pH value of the sludge; the first pH controller is connected to an external PLC control system, and the first pH controller measures the pH value of the sludge through a first measuring electrode (A6.1); the first measuring electrode is arranged at the measuring hole and a protective net is provided on the outer side of the measuring electrode.

5. The sludge phosphorus release and phosphorus crystal recovery device according to claim 3 is characterized in that: The inner wall of the first accommodating cavity (A1.1) is also provided with a plurality of protrusions (A1.3) facing the center of the first accommodating cavity; the protrusions (A1.3) are hemispherical protrusions with a radius of 40-80 mm; the plurality of protrusions (A1.3) are evenly distributed on the inner wall of the first accommodating cavity.

6. The sludge phosphorus release and phosphorus crystal recovery device according to claim 3, characterized in that: The first stirring shaft (A2.2) is provided with multiple layers of the first stirring blades (A2.3) at intervals along its axial direction; The first body (A1.2) is also provided with a first odor collecting pipe (A7) for collecting odor generated in the first accommodating chamber; the first shell (A1) also includes an opening connected to the first accommodating chamber (A1.1), and a detachable cover (A1.4) is provided at the opening; the first driving power source (A2.1), the first dosing pipe (A5), the first pH controller (A6) and the first odor collecting pipe (A7) are all arranged on the detachable cover (A1.4).

7. The sludge phosphorus release and phosphorus crystal recovery device according to claim 3 is characterized in that: The pH value adjustment unit (2.2) comprises a second shell (B1), a second stirring assembly (B2), a second mud inlet pipe (B3) and a second mud outlet pipe (B4); The second shell (B1) comprises a second body (B1.2) having a second accommodating cavity (B1.1); the second mud inlet pipe (B3) and the second mud outlet pipe (B4) are both arranged on the second body (B1.2) and are both connected to the second accommodating cavity (B1.1); The second body (B1.2) is provided with a second drug adding pipe (B5) communicating with the second accommodating cavity (B1.1); The second stirring component (B2) comprises a second driving power source (B2.1), a second stirring shaft (B2.2) and a second stirring blade (B2.3); the second driving power source (B2.1) is arranged on the second shell (B1); the connecting end of the second stirring shaft (B2.2) is connected to the output end of the second driving power source (B2.1); the free end of the second stirring shaft (B2.2) is arranged in the second accommodating cavity (B1.1) and the second stirring blade (B2.3) is arranged thereon; The fourth pipeline (7) is in communication with the second mud inlet pipe (B3), and the second mud outlet pipe (B4) is in communication with the third pipeline (6).

8. The sludge phosphorus release and phosphorus crystal recovery device according to claim 1, characterized in that: A water collecting tank (8.4) is provided at the upper part of the first columnar cylinder (8.1.1), and the liquid rising through the second water flow rising channel (C) is collected in the water collecting tank (8.4) and then discharged through the liquid discharge pipe (8.6); The micro-nano aeration plate (8.12) is located 0.2 to 0.3 m below the bottom end of the bottom columnar cylinder (8.3.3).

9. The sludge phosphorus release and phosphorus crystal recovery device according to claim 1, characterized in that: The plug-flow stirring assembly (8.8) comprises a third driving power source (8.8.1), a third stirring shaft (8.8.2) and a third stirring blade (8.8.3); the connection end of the third stirring shaft (8.8.2) is connected to the output end of the third driving power source (8.8.1); the third stirring blade (8.8.3) is arranged on the free end of the third stirring shaft (8.8.2); the water outlet end of the liquid inlet pipe (8.5) is located 20-50 cm above the third stirring blade (8.8.3).

10. The sludge phosphorus release and phosphorus crystal recovery device according to claim 1, characterized in that: The folded plate vortex component (8.9) is located directly below the plug-flow stirring component (8.8), and the folded plate vortex component (8.9) comprises a first folded plate (8.9.1) and a second folded plate (8.9.2) arranged in parallel, the first folded plate (8.9.1) comprises a plurality of connecting plates connected in sequence, and the angle α between two adjacent connecting plates is 80°-100°; the first folded plate (8.9.1) and the second folded plate (8.9.2) are in a mirror image structure; The modular vortex assembly (8.10) comprises a plurality of vortex monomers stacked or spaced apart, wherein the vortex monomer is a hollow columnar body formed by a first vertical plate (8.10.1), a second vertical plate (8.10.2), an upper arc-shaped outer frame (8.10.3), an upper arc-shaped inner frame (8.10.4), a lower arc-shaped outer frame (8.10.5) and a lower arc-shaped inner frame (8.10.6); a vortex sheet is installed in the vortex monomer, and the cross-section of the vortex sheet is at least one of a triangle, a semicircle and a rectangle; The inclined plate assembly (8.11) comprises a plurality of settling inclined plates arranged in parallel, the settling inclined plates being arranged at an angle to the inner wall of the first columnar barrel (8.1.1); and the inclined plate assembly (8.11) is located in the middle and lower part of the first columnar barrel (8.1.1).

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