CN114772781A - Recovery system and process for phosphorus microcrystals in sewage - Google Patents

Recovery system and process for phosphorus microcrystals in sewage Download PDF

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Publication number
CN114772781A
CN114772781A CN202210423310.9A CN202210423310A CN114772781A CN 114772781 A CN114772781 A CN 114772781A CN 202210423310 A CN202210423310 A CN 202210423310A CN 114772781 A CN114772781 A CN 114772781A
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phosphorus
tank
sewage
sludge
induced crystallization
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吕锡武
郭婷
李想
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Southeast University
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Southeast University
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/32—Phosphates of magnesium, calcium, strontium, or barium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/37—Phosphates of heavy metals
    • C01B25/375—Phosphates of heavy metals of iron
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/45—Phosphates containing plural metal, or metal and ammonium
    • C01B25/451—Phosphates containing plural metal, or metal and ammonium containing metal and ammonium
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F2001/5218—Crystallization
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/105—Phosphorus compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00—General aspects of water treatment
    • C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/30—Aerobic and anaerobic processes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/30—Aerobic and anaerobic processes
    • C02F3/308—Biological phosphorus removal

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Removal Of Specific Substances (AREA)

Abstract

The invention relates to a recovery system and a process of phosphorus microcrystals in sewage, wherein the system comprises an induced crystallization device, a hydraulic cyclone separator and a microcrystals recovery tank, wherein the hydraulic cyclone separator is communicated with the induced crystallization device through a crystal conveying pipeline; the induced crystallization device comprises at least 1-level induced crystallization columns which are connected in series, a sewage inlet, a medicament inlet and an alkali liquor inlet are formed in the side wall of the lower part of each induced crystallization column, a gas inlet is formed in the bottom of each induced crystallization column, and a liquid outlet is formed in the top of each induced crystallization column; the medicament import is provided with the liquid medicine storage tank through the medicament pipeline, the alkali lye import is provided with the alkali lye storage tank through the alkali lye pipeline, gas inlet is provided with the aeration machine through aeration pipeline. The invention utilizes the hydrocyclone separator to separate and recover the phosphorus microcrystals, improves the recovery rate of the phosphorus microcrystals and has low equipment cost.

Description

Recovery system and process for phosphorus microcrystals in sewage
Technical Field
The invention belongs to the field of sewage treatment and resource recovery, and particularly relates to a system and a process for recovering phosphorus microcrystals in sewage.
Background
Under the guidance of the strategic idea of sustainable development of water treatment, the recycling of phosphorus resources is realized while sewage is treated, and the method becomes a research hotspot at present; the method can realize resource recycling, solve the problem of depletion of phosphorite resources, avoid eutrophication of the water body and improve the ecological health of the water body. However, the existing methods for recovering phosphorus from sewage include adsorption, chemical precipitation, and induced crystallization, which have the following problems: the adsorption method needs desorption and regeneration of the adsorbent, so that the production cost is high; the chemical precipitation dephosphorization method can generate a large amount of precipitated sludge, and the product has high water content, low purity and larger recovery difficulty; the induced crystallization method is easy to generate homogeneous precipitation in an induced crystallization reactor, so that the yield of the phosphorus microcrystal is high, and the microcrystal is easy to run off along with the effluent, so that the recovery rate of the phosphorus microcrystal is low, therefore, a sedimentation tank, a screen and a coagulant are often required to be arranged to intercept the phosphorus microcrystal, and the equipment cost is greatly increased.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a system and a process for recovering phosphorus microcrystals in sewage. In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the first technical scheme is as follows:
a system for recovering phosphorus microcrystals in sewage comprises an induced crystallization device, a hydrocyclone communicated with the induced crystallization device through a crystal conveying pipeline, and a microcrystals recovery tank arranged at the bottom of the hydrocyclone; the induced crystallization device comprises an induced crystallization column of at least 1 level, a sewage inlet, a medicament inlet and an alkali liquor inlet are arranged on the side wall of the lower part of the induced crystallization column, a gas inlet is arranged at the bottom of the induced crystallization column, and a liquid outlet is arranged at the top of the induced crystallization column; the medicament import is provided with the liquid medicine storage tank through the medicament pipeline, the alkali lye import is provided with the alkali lye storage tank through the alkali lye pipeline, the gas inlet is provided with the aeration machine through aeration pipeline.
Further, when the induced crystallization columns are in a multi-stage mode, the multi-stage induced crystallization columns are connected in series, the adjacent two stages of induced crystallization columns are communicated through a liquid transfer pipeline, a liquid discharge port of the last stage induced crystallization column is communicated with a feed port of the hydrocyclone through a crystal conveying pipeline, one end of the liquid transfer pipeline is connected with the liquid discharge port of the induced crystallization column, and the other end of the liquid transfer pipeline is connected with a sewage inlet of the next adjacent stage induced crystallization column.
Furthermore, power pumps are arranged on the liquid transfer pipeline, the medicament pipeline, the alkali liquor pipeline and the crystal conveying pipeline.
Further, the hydrocyclone separator comprises a shell, an overflow pipe, a feeding hole and an underflow pipe, wherein the upper part of the shell is cylindrical, and the lower part of the shell is inverted conical; the underflow pipe extends into the microcrystal recovery tank, the feed inlet is arranged in a tangent line of the cylindrical shell, and the overflow pipe extends into the shell.
Further, the feed inlet is a square opening; the cone angle of the inverted cone is less than or equal to 15 degrees.
The second technical scheme is as follows:
a process for recovering phosphorus using the phosphorus crystallite recovery system, comprising:
step A: adding a chemical agent, an alkali liquor and a seed crystal into the induced crystallization reactor, and stirring the feed liquid by using the airflow of an aeration device, so that phosphorus in the sewage is subjected to induced crystallization reaction under the condition of pH of 8-10 to form phosphorus microcrystals;
and B, step B: discharging the effluent of the induced crystallization reactor into a hydrocyclone, and separating the phosphorus microcrystals by using centrifugal force under the high-speed rotation of the feed liquid.
Further, the chemical agent is any one of calcium salt, magnesium salt and iron salt, when the chemical agent is calcium salt, the phosphorus microcrystal is calcium hydroxy phosphate, when the chemical agent is magnesium salt, the phosphorus microcrystal is magnesium ammonium phosphate, and when the chemical agent is iron salt, the phosphorus microcrystal is vivianite;
the seed crystal is one or more of calcite, quartz sand or hydroxyapatite.
The technical scheme is as follows:
a sewage treatment system comprising the phosphorus microcrystal recovery system, which comprises an anaerobic tank, a first sedimentation tank, the phosphorus microcrystal recovery system as defined in any one of claims 1-5, a nitrification tank, a second sedimentation tank, an anoxic tank, a post-aeration tank and a third sedimentation tank which are sequentially communicated; a main sewage inlet is formed in the anaerobic tank, and a purified water discharge port is formed in the third sedimentation tank;
furthermore, the water outlet of the anaerobic tank is communicated with the water inlet of the first sedimentation tank through a first sewage pipeline, the water outlet of the first sedimentation tank is communicated with the sewage inlet of the first-stage induced crystallization column through a second sewage pipeline, the water outlet of the first sedimentation tank is communicated with the nitrification tank through a third sewage pipeline, the overflow pipe of the hydrocyclone is communicated with the water inlet of the nitrification tank through a fourth sewage pipeline, the water outlet of the nitrification tank is communicated with the water inlet of the second sedimentation tank through a fifth sewage pipeline, the water outlet of the second sedimentation tank is communicated with the anoxic tank through a sixth sewage pipeline, the water outlet of the anoxic tank is communicated with the water inlet of the post-aeration tank through a seventh sewage pipeline, and the water outlet of the post-aeration tank is communicated with the water inlet of the third sedimentation tank.
Further, a sludge discharge port of the first sedimentation tank is communicated with a sludge inlet of the anoxic tank through a first sludge pipeline; a first sludge discharge pipe is arranged on the second sedimentation tank, a first sludge discharge port communicated with the outside is arranged on the first sludge discharge pipe, and the first sludge discharge pipe is also communicated with a sludge inlet of the nitrification tank through a second sludge pipeline; and a second sludge discharge pipe is arranged on the third sedimentation tank, a second sludge discharge port communicated with the outside is arranged on the sludge discharge pipe, and the second sludge discharge pipe of the third sedimentation tank is also communicated with the anaerobic tank through a third sludge pipeline.
The technical scheme is as follows:
a sewage treatment process utilizing the sewage treatment system comprises the following steps:
step 1: after the sewage enters the anaerobic tank, the sewage is fully mixed with the denitrification phosphorus-accumulating sludge reflowing from the third sedimentation tank under the action of the stirring paddle of the anaerobic tank, the denitrification phosphorus-accumulating sludge absorbs organic matters in the water, a carbon source is stored in the form of Poly-beta-Hydroxybutyrate (PHB) and generates anaerobic phosphorus release at the same time,
step 2, discharging the sludge-water mixture in the anaerobic tank into a first sedimentation tank for sludge-water separation, allowing part of separated supernatant to enter a nitrification tank, allowing the other part of separated supernatant to enter an induced crystallization device, crystallizing phosphorus in sewage on the surface of a seed crystal under the action of a chemical agent in an induced crystallization column to form phosphorus microcrystals, allowing feed liquid to enter a water cyclone separator, separating the phosphorus microcrystals from the sewage, allowing the separated phosphorus microcrystals to enter a microcrystal recovery tank, and allowing supernatant discharged by an overflow pipe to enter the nitrification tank; the activated sludge of the denitrifying phosphorus accumulating bacteria which is separated out and is rich in PHB is discharged into a subsequent anoxic tank;
step 3, under the action of nitrifying bacteria in the nitrification tank, converting ammonia nitrogen in the sewage into nitrate, and providing an electron acceptor for the denitrification phosphorus accumulation reaction in the subsequent anoxic tank;
step 4, enabling the sewage in the nitrification tank to enter a second sedimentation tank for sludge-water separation, enabling the supernatant to enter an anoxic tank, enabling part of sludge to flow back into the nitrification tank, and discharging the rest sludge to the outside;
step 5, in the anoxic tank, stirring and mixing activated sludge of the denitrifying phosphorus accumulating bacteria rich in PHB with the supernatant by using a stirring paddle, wherein the denitrifying phosphorus accumulating bacteria take nitrate as an electron acceptor, and perform synchronous denitrifying phosphorus accumulating reaction by using a stored carbon source, and after phosphorus absorption and denitrification are finished, the sewage in the anoxic tank enters a post-aeration tank;
step 6: and after further absorbing phosphorus, the sewage entering the post-aeration tank enters a third sedimentation tank for sludge-water separation, the supernatant is discharged, part of sludge flows back to the anaerobic tank for phosphorus release, and the rest sludge is discharged.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, the hydrocyclone separator is additionally arranged behind the phosphorus microcrystal reactor, so that the microcrystal loss along with effluent can be reduced, the phosphorus recovery rate in the system is improved, and the hydrocyclone separator has the advantages of simple structure, convenience and quickness in operation, small space requirement, wide treatment range and the like, and the processing difficulty and the operation and maintenance cost are effectively reduced; compared with the traditional technology, the technology of intercepting the phosphorus microcrystals by adopting a sedimentation tank, a screen and the like reduces the equipment cost.
2. The invention adopts the multi-stage induced crystallization column to carry out the induced crystallization of the phosphorus, and the obtained crystal has large particles, thereby being convenient for the recovery and separation of phosphorus microcrystals and improving the recovery rate.
3. The invention couples the phosphorus recovery system with the sewage treatment system, can realize the crystallization recovery of phosphorus resources in the sewage treatment process, and improves the sewage treatment and phosphorus resource recovery efficiency.
Drawings
FIG. 1 is a schematic diagram of the configuration of a phosphorus crystallite recovery system in accordance with one embodiment of the present invention;
FIG. 2 is a schematic view showing the structure of a sewage treatment system according to an embodiment of the present invention;
in the figure: 1. an induced crystallization column, 2, a crystal conveying pipeline, 3, a hydrocyclone, 4, a microcrystal recovery tank, 5, a medicament pipeline, 6, a liquid medicine storage tank, 7, an alkali liquor pipeline, 8, an alkali liquor storage tank, 9, an aeration pipeline, 10, an aerator, 11, a liquid transfer pipeline, 12, a power pump, 13, a sewage pipeline, 14, a sewage storage tank, 15, an anaerobic tank, 16, a first sedimentation tank, 17, a nitrification tank, 18, a second sedimentation tank, 19, an anoxic tank, 20, a post-aeration tank, 21, a third sedimentation tank, 22, a total sewage inlet, 23, a purified water discharge port, 24, a first sewage pipeline, 25, a second sewage pipeline, 26 and a third sewage pipeline; 27. a fourth sewage conduit, 28, a fifth sewage conduit, 29, a sixth sewage conduit, 30, a seventh sewage conduit, 31, an eighth sewage conduit, 32, a first sludge conduit, 33, a first sludge conduit, 34, a first sludge discharge port, 35, a second sludge conduit, 36, a second sludge conduit, 37, a second sludge discharge port, 38, a third sludge conduit, 39, a stirring paddle, 40, a housing, 41, an overflow pipe, 42, a feed inlet, 43, an underflow pipe.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The meaning of the above terms in the present invention can be understood in a specific case by those skilled in the art.
The present invention will be described in further detail with reference to the accompanying drawings.
Example 1:
the system for recovering phosphorus microcrystals in sewage comprises an induced crystallization device, a hydrocyclone 3 communicated with the induced crystallization device through a crystal conveying pipeline 2, and a microcrystallite recovery tank 4 arranged at the bottom of the hydrocyclone 3, wherein the microcrystals are obtained by separating phosphorus microcrystals from sewage; the induced crystallization device comprises an induced crystallization column 1 with at least 1 level, the side wall of the lower part of the induced crystallization column 1 is provided with a sewage inlet, a medicament inlet and an alkali liquor inlet, the bottom of the induced crystallization column 1 is provided with a gas inlet, and the top of the induced crystallization column 1 is provided with a liquid outlet; the medicament import is provided with liquid medicine storage tank 6 through medicament pipeline 5, the alkali lye import is provided with alkali lye storage tank 8 through alkali lye pipeline 7, the gas import is provided with aeration machine 10 through aeration pipeline 9. According to the invention, the hydrocyclone 3 separator is additionally arranged behind the phosphorus microcrystal reactor, so that the microcrystal loss along with effluent can be reduced, the phosphorus recovery rate in the system is improved, and the hydrocyclone 3 has the advantages of simple structure, convenience and quickness in operation, small space requirement, wide treatment range and the like, and the processing difficulty and the operation and maintenance cost are effectively reduced; compared with the traditional technology, the technology of intercepting the phosphorus microcrystals by adopting a sedimentation tank, a screen and the like reduces the equipment cost. The invention adopts the multistage induced crystallization column 1 to carry out the induced crystallization of phosphorus, and the obtained crystal has large particles, thereby being convenient for the recovery and separation of phosphorus microcrystals and improving the recovery rate.
Further, the sewage inlet is provided with a sewage storage tank 14 through a sewage pipeline 13.
As an embodiment of the recovery system of phosphorus microcrystals in sewage, when the induced crystallization columns 1 are in multiple stages, the induced crystallization columns 1 in adjacent two stages are connected in series, the liquid discharge port of the induced crystallization column in the last stage is communicated with the feed port 42 of the hydrocyclone 3 through a crystal conveying pipeline, one end of the liquid discharge pipeline 11 is connected with the liquid discharge port of the induced crystallization column 1, and the other end of the liquid discharge pipeline 11 is connected with the sewage inlet of the induced crystallization column in the next stage. When the induced crystallization column 1 is a level 1 induced crystallization column, the induced crystallization column is simultaneously used as a first-level induced crystallization column and a last-level induced crystallization column.
As an embodiment of the system for recovering the phosphorus microcrystals in the sewage, the liquid transfer pipeline 11, the medicament pipeline 5, the alkali liquor pipeline 7 and the crystal conveying pipeline 2 are all provided with a power pump 12.
As an embodiment of the system for recovering phosphorus microcrystals in sewage water, the hydrocyclone 3 comprises a shell 40 with a cylindrical upper part and an inverted cone lower part, an overflow pipe 41 arranged at the top of the shell 40, a feed inlet 42 arranged at the upper part of the side wall of the shell 40, and an underflow pipe 43 arranged at the bottom of the shell 40; the underflow pipe 43 extends into the microcrystal recovery tank 4, the feed inlet 42 is arranged tangentially to the cylindrical shell 40, and the overflow pipe 41 extends into the shell 40.
As an embodiment of the system for recovering phosphorus microcrystals in sewage, the feed port 42 is a square port; the cone angle of the inverted cone is less than or equal to 15 degrees.
Example 2:
a process for recovering phosphorus using the phosphorus crystallite recovery system of example 1, comprising:
step A: adding a chemical agent, an alkali liquor and a seed crystal into the induced crystallization reactor, and stirring the feed liquid by utilizing the airflow of an aeration device, so that the phosphorus in the sewage is subjected to induced crystallization reaction under the condition of pH of 8-10 to form phosphorus microcrystals;
and B: discharging the effluent of the induced crystallization reactor into a hydrocyclone 3, and separating phosphorus microcrystals by using centrifugal force under the high-speed rotation of the feed liquid.
Further, the chemical agent is any one of calcium salt, magnesium salt and iron salt, when the chemical agent is calcium salt, the phosphorus microcrystal is calcium hydroxy phosphate, when the chemical agent is magnesium salt, the phosphorus microcrystal is magnesium ammonium phosphate, and when the chemical agent is iron salt, the phosphorus microcrystal is vivianite;
the seed crystal adopts one or more of calcite, quartz sand or hydroxyapatite.
Under the action of external power, a water flow mixture containing microcrystals is pushed into a hydrocyclone 3 at a higher speed, the water flow mixture containing microcrystals enters along the tangential direction of the hydrocyclone 3 to promote a feed liquid to do rotary motion along a cylinder wall, and in the rotary motion process, microcrystals are acted by centrifugal force; the separated liquid rotates downwards to continue moving, and after entering the inverted cone section, the inner diameter of the hydrocyclone 3 is gradually reduced, the liquid rotating speed is accelerated, so that the pressure distribution of the liquid along the radial direction is not uniform when the liquid generates vortex, the liquid is smaller at the position closer to the axis and approaches to zero when the liquid reaches the axis, and becomes a low-pressure area or even a vacuum area, so that the liquid tends to move along the axis direction, meanwhile, because the caliber of the underflow pipe 43 of the hydrocyclone is greatly reduced, the liquid cannot be rapidly discharged from the underflow pipe 43, and an overflow port in the center of a top cover in the hydrocyclone 3 is positioned at the low-pressure area, a part of the liquid moves towards the overflow port, so that the upward rotating motion is formed, the liquid is discharged from the overflow port, and solid-liquid separation is realized.
Example 3:
fig. 2 shows an embodiment of a sewage treatment system according to the present invention, which comprises an anaerobic tank 15, a first sedimentation tank 16, a phosphorus crystallite recovery system, a nitrification tank 17, a second sedimentation tank 18, an anoxic tank 19, a post-aeration tank 20, and a third sedimentation tank 21, which are connected in sequence; a main sewage inlet 22 is arranged on the anaerobic tank 15, and a purified water discharge port 23 is arranged on the third sedimentation tank 21; the phosphorus microcrystal recovery system comprises an induced crystallization device, a hydraulic cyclone separator 3 communicated with the induced crystallization device through a crystal conveying pipeline 2, and a microcrystal recovery tank 4 arranged at the bottom of the hydraulic cyclone separator 3; the induced crystallization device comprises 3-level induced crystallization columns 1 which are connected in series, a sewage inlet, a medicament inlet and an alkali liquor inlet are formed in the side wall of the lower portion of each induced crystallization column 1, a gas inlet is formed in the bottom of each induced crystallization column 1, and a liquid discharge port is formed in the top of each induced crystallization column 1; the medicament import is provided with liquid medicine storage tank 6 through medicament pipeline 5, the alkali lye import is provided with alkali lye storage tank 8 through alkali lye pipeline 7, the gas import is provided with aeration machine 10 through aeration pipeline 9. The invention couples the phosphorus recovery system with the sewage treatment system, can realize the crystallization recovery of phosphorus resources in the sewage treatment process, and improves the sewage treatment and phosphorus resource recovery efficiency.
Further, the induced crystallization columns 1 of two adjacent stages are communicated through a liquid transfer pipeline 11, a liquid discharge port of the induced crystallization column at the last stage is communicated with a feed port 42 of the hydrocyclone 3 through a crystal conveying pipeline 2, one end of the liquid transfer pipeline 11 is connected with the liquid discharge port of the induced crystallization column 1, and the other end of the liquid transfer pipeline 11 is connected with a sewage inlet of the induced crystallization column at the next adjacent stage.
Further, the water outlet of the anaerobic tank 15 is communicated with the water inlet of the first sedimentation tank 16 through a first sewage pipeline 24, the water outlet of the first sedimentation tank 16 is communicated with the sewage inlet of the first-stage induced crystallization column through a second sewage pipeline 25, is communicated with the nitrification tank 17 through a third sewage conduit 26, an overflow pipe 41 of the hydrocyclone 3 is communicated with the water inlet of the nitrification tank 17 through a fourth sewage conduit 27, the water outlet of the nitrification tank 17 is communicated with the water inlet of the second sedimentation tank 18 through a fifth sewage pipeline 28, the water outlet of the second sedimentation tank 18 is communicated with the anoxic tank 19 through a sixth sewage pipeline 29, the water outlet of the anoxic tank 19 is communicated with the water inlet of the post aeration tank 20 through a seventh sewage pipeline 30, the water outlet of the post aeration tank 20 is communicated with the water inlet of the third sedimentation tank 21.
As an embodiment of a sewage treatment and recovery system of the present invention, the sludge discharge port of the first sedimentation tank 16 is communicated with the sludge inlet port of the anoxic tank 19 through a first sludge conduit 32; a first sludge discharge pipe 33 is arranged on the second sedimentation tank 18, a first sludge discharge port 34 communicated with the outside is arranged on the first sludge discharge pipe 33, and the first sludge discharge pipe 33 is also communicated with a sludge inlet of the nitrification tank 17 through a second sludge pipeline 35; and a second sludge discharge pipe 36 is arranged on the third sedimentation tank 21, a second sludge discharge port 37 communicated with the outside is arranged on the sludge discharge pipe, and the second sludge discharge pipe 36 of the third sedimentation tank 21 is also communicated with the anaerobic tank 15 through a third sludge pipeline 38.
As an embodiment of the sewage treatment and recovery system, the liquid transfer pipeline 11, the chemical pipeline 5, the alkaline liquor pipeline 7, the first sludge pipeline 32, the second sludge pipeline 35, the third sludge pipeline 38 and the crystal conveying pipeline 2 are all provided with a power pump 12.
As an embodiment of a sewage treatment and recovery system of the present invention, the hydrocyclone 3 comprises a housing 40 having a cylindrical upper portion and an inverted conical lower portion, an overflow pipe 41 disposed at the top of the housing 40, a feed inlet 42 disposed at the upper portion of the sidewall of the housing 40, and an underflow pipe 43 disposed at the bottom of the housing 40; the underflow pipe 43 extends into the microcrystal recovery tank 4, the feed port 42 is arranged tangentially to the cylindrical shell 40, and the overflow pipe 41 extends into the shell 40.
As an embodiment of a sewage treatment and recovery system of the present invention, the feed port 42 is a square port; the cone angle of the inverted cone is less than or equal to 15 degrees.
As an embodiment of the sewage treatment and recovery system of the present invention, the anaerobic tank 15 and the anoxic tank 19 are provided therein with stirring paddles 39.
Example 4:
a sewage treatment process using the sewage treatment system of example 3, comprising the steps of:
step 1: after the sewage enters the anaerobic tank 15, the sewage is fully mixed with the denitrification phosphorus-accumulating sludge refluxed by the third sedimentation tank 21 under the action of the stirring paddle 39 of the anaerobic tank 15, the denitrification phosphorus-accumulating sludge absorbs organic matters in the water, a carbon source is stored in the form of Poly-beta-Hydroxybutyrate (PHB) and anaerobic phosphorus release is carried out at the same time,
step 2, discharging the mud-water mixture in the anaerobic tank 15 into a first sedimentation tank 16 for mud-water separation, allowing the separated supernatant to enter a nitrification tank 17, allowing the other supernatant to enter an induced crystallization device, and in the induced crystallization column 1, inducing and crystallizing phosphorus in the sewage under the action of chemical agents and seed crystals to form phosphorus microcrystals (the chemical agents adopt calcium chloride and Ca)2+And PO in the induced crystallization column 14 3-The molar concentration ratio of the phosphorus to the nitrogen is 1.5-3: 1, the added crystal seeds are calcite or quartz sand, the particle size of the crystal seeds is 0.1-0.5 mm, the adding amount is 30-40 g/L ], then the feed liquid enters a water cyclone separator, the phosphorus microcrystals and sewage are separated, the separated phosphorus microcrystals enter a microcrystallite recovery tank 4, and the supernatant discharged by an overflow pipe 41 enters a nitrification tank 17; the activated sludge of the denitrifying phosphorus accumulating bacteria rich in PHB is separated and discharged into a subsequent anoxic tank 19;
step 3, under the action of nitrifying bacteria in the nitrification tank 17, converting ammonia nitrogen in the sewage into nitrate, and providing an electron acceptor for the denitrification phosphorus accumulation reaction in the subsequent anoxic tank 19;
step 4, the sewage in the nitrification tank 17 enters a second sedimentation tank 18 for mud-water separation, the supernatant enters an anoxic tank 19, part of the sludge flows back into the nitrification tank 17, and the rest sludge is discharged to the outside;
step 5, in the anoxic tank 19, stirring and mixing the activated sludge of the denitrifying phosphorus accumulating bacteria rich in PHB with the supernatant by a stirring paddle 39, taking nitrate as an electron acceptor by the denitrifying phosphorus accumulating bacteria, performing synchronous denitrifying phosphorus accumulating reaction by using a stored carbon source, and after phosphorus absorption and denitrification are finished, feeding the sewage in the anoxic tank 19 into a post-aeration tank 20;
step 6: and after further absorbing phosphorus, the sewage entering the post-aeration tank enters a third sedimentation tank 21 for sludge-water separation, the supernatant is discharged, part of sludge flows back to the anaerobic tank 15 for phosphorus release, and the rest sludge is discharged.
According to the invention, because the anaerobic tank 15 releases phosphorus anaerobically, the supernatant of the first sedimentation tank 16 is rich in a large amount of phosphorus, when the phosphorus concentration is higher, the induced crystallization reaction is more favorably generated, the plurality of induced crystallization columns 1 are connected in series, and each induced crystallization column 1 comprises an aeration system, so that carbon dioxide can be blown off through aeration to improve the pH value of sewage, the generation of crystallization is also favorably promoted, and meanwhile, the feed liquid in the whole induced crystallization column 1 can be fluidized to be beneficial to fully contacting the seed crystal with the liquid.
The embodiments described above are only preferred embodiments of the present invention and are not exhaustive of the possible implementations of the present invention. Any obvious modifications thereof, which would occur to one skilled in the art without departing from the principles and spirit of the invention, are to be considered as included within the scope of the following claims.

Claims (10)

1. The system for recovering phosphorus microcrystals in sewage is characterized by comprising an induced crystallization device, a hydraulic cyclone separator (3) communicated with the induced crystallization device through a crystal conveying pipeline (2), and a microcrystals recovery tank (4) arranged at the bottom of the hydraulic cyclone separator (3); the induced crystallization device comprises an induced crystallization column (1) of at least 1 level, a sewage inlet, a medicament inlet and an alkali liquor inlet are arranged on the side wall of the lower part of the induced crystallization column (1), a gas inlet is arranged at the bottom of the induced crystallization column (1), and a liquid outlet is arranged at the top of the induced crystallization column (1); the medicament import is provided with liquid medicine storage tank (6) through medicament pipeline (5), the alkali liquor import is provided with alkali liquor storage tank (8) through alkali liquor pipeline (7), the gas import is provided with aeration machine (10) through aeration pipeline (9).
2. The system for recovering phosphorus microcrystals in sewage as claimed in claim 1, wherein when the induced crystallization columns (1) are in multiple stages, the induced crystallization columns in multiple stages are connected in series, the induced crystallization columns (1) in two adjacent stages are communicated through a liquid transfer pipeline (11), the liquid discharge port of the induced crystallization column in the last stage is communicated with the feed port (42) of the hydrocyclone (3) through a crystal conveying pipeline (2), one end of the liquid transfer pipeline (11) is connected with the liquid discharge port of the induced crystallization column (1), and the other end of the liquid transfer pipeline is connected with the sewage inlet of the induced crystallization column in the next adjacent stage.
3. The system for recovering phosphorus microcrystals in sewage as claimed in claim 2, wherein a power pump (12) is arranged on the liquid transfer pipeline (11), the medicament pipeline (5), the alkali liquor pipeline (7) and the crystal conveying pipeline (2).
4. The system for recovering phosphorus from wastewater according to claim 1,
the hydrocyclone separator (3) comprises a shell (40) with a cylindrical upper part and an inverted-cone lower part, an overflow pipe (41) arranged at the top of the shell (40), a feed inlet (42) arranged at the upper part of the side wall of the shell (40) and an underflow pipe (43) arranged at the bottom of the shell (40); the underflow pipe (43) extends into the microcrystal recovery tank (4), the feed port (42) and the tangent of the cylindrical shell (40) are arranged, and the overflow pipe (41) extends into the shell (40).
5. The system for recovering phosphorus microcrystals in sewage as claimed in claim 4,
the feed port (42) is a square port; the cone angle of the inverted cone is less than or equal to 15 degrees.
6. A process for recovering phosphorus using the phosphorus crystallite recovery system of any one of claims 1 to 5, comprising:
step A: adding a chemical agent, an alkali liquor and a seed crystal into the induced crystallization reactor, and stirring the feed liquid by using the airflow of an aeration device, so that phosphorus in the sewage is subjected to induced crystallization reaction under the condition of pH of 8-10 to form phosphorus microcrystals;
and B: discharging the effluent of the induced crystallization reactor into a hydrocyclone (3), and separating phosphorus microcrystals by utilizing centrifugal force under the high-speed rotation of feed liquid.
7. The process for recovering phosphorus using a phosphorus microcrystals recovery system as claimed in claim 6,
the chemical agent is any one of calcium salt, magnesium salt and iron salt, when the chemical agent is calcium salt, the phosphorus microcrystal is calcium hydroxy phosphate, when the chemical agent is magnesium salt, the phosphorus microcrystal is magnesium ammonium phosphate, and when the chemical agent is iron salt, the phosphorus microcrystal is vivianite;
the seed crystal adopts one or more of calcite, quartz sand or hydroxyapatite.
8. A sewage treatment system comprising the phosphorus crystallite recovery system according to any one of claims 1 to 5, characterized by comprising an anaerobic tank (15), a first sedimentation tank (16), the phosphorus crystallite recovery system according to any one of claims 1 to 5, a nitrification tank (17), a second sedimentation tank (18), an anoxic tank (19), a post-aeration tank (20) and a third sedimentation tank (21) which are communicated in sequence; the anaerobic tank (15) is provided with a main sewage inlet (22), and the third sedimentation tank (21) is provided with a purified water discharge port (23).
9. A sewage treatment system according to claim 8 wherein the sludge outlet of said first sedimentation tank (16) communicates with the sludge inlet of said anoxic tank (19) via a first sludge conduit (32); a first sludge discharge pipe (33) is arranged on the second sedimentation tank (18), a first sludge discharge port (34) communicated with the outside is formed in the first sludge discharge pipe (33), and the first sludge discharge pipe (33) is also communicated with a sludge inlet of the nitrification tank (17) through a second sludge pipeline (35); and a second sludge discharge pipe (36) is arranged on the third sedimentation tank (21), a second sludge discharge port (37) communicated with the outside is arranged on the sludge discharge pipe, and the second sludge discharge pipe (36) of the third sedimentation tank (21) is also communicated with the anaerobic tank (15) through a third sludge pipeline (38).
10. A sewage treatment process using the sewage treatment system according to any one of claims 8 to 9, comprising the steps of:
step 1: after entering the anaerobic tank (15), the sewage is fully mixed with the denitrification phosphorus-accumulating sludge reflowing from the third sedimentation tank (21) under the action of a stirring paddle (39) of the anaerobic tank (15), the denitrification phosphorus-accumulating sludge absorbs organic matters in water, a carbon source is stored in a poly-beta-hydroxybutyrate form, and anaerobic phosphorus release is carried out at the same time,
step 2, discharging a sludge-water mixture in the anaerobic tank (15) into a first sedimentation tank (16) for sludge-water separation, allowing a separated supernatant part to enter a nitrification tank (17), allowing the other part to enter an induced crystallization device, allowing phosphorus in sewage to crystallize on the surface of a seed crystal under the action of a chemical agent in an induced crystallization column (1) to form phosphorus microcrystals, allowing a feed liquid to enter a water cyclone separator for separating the phosphorus microcrystals from the sewage, allowing the separated phosphorus microcrystals to enter a microcrystal recovery tank (4), and allowing a supernatant discharged from an overflow pipe (41) to enter the nitrification tank (17); the activated sludge of the denitrifying phosphorus accumulating bacteria which is separated out and is rich in PHB is discharged into a subsequent anoxic tank (19);
step 3, under the action of nitrifying bacteria in the nitrification tank (17), converting ammonia nitrogen in the sewage into nitrate, and providing an electron acceptor for the subsequent denitrification phosphorus accumulation reaction in the anoxic tank (19);
step 4, enabling the sewage in the nitrification tank (17) to enter a second sedimentation tank (18) for mud-water separation, enabling the supernatant to enter an anoxic tank (19), enabling part of sludge to flow back into the nitrification tank (17), and discharging the rest sludge to the outside;
step 5, in the anoxic tank (19), stirring and mixing the activated sludge of the denitrifying phosphorus-accumulating bacteria rich in PHB with the supernatant by a stirring paddle (39), wherein the denitrifying phosphorus-accumulating bacteria take nitrate as an electron acceptor, and utilize a stored carbon source to perform synchronous denitrifying phosphorus-accumulating reaction, and after phosphorus absorption and denitrification are finished, sewage in the anoxic tank (19) enters a post-aeration tank (20);
and 6: and after further absorbing phosphorus, the sewage entering the post-aeration tank enters a third sedimentation tank (21) for sludge-water separation, the supernatant is discharged, part of sludge flows back to the anaerobic tank (15) for phosphorus release, and the rest sludge is discharged.
CN202210423310.9A 2022-04-21 2022-04-21 Recovery system and process for phosphorus microcrystals in sewage Pending CN114772781A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102372353A (en) * 2011-08-03 2012-03-14 东华大学 Spiral-flow type crystal phosphorous removal reactor
CN110015814A (en) * 2019-04-23 2019-07-16 东南大学 A kind of synchronous device and method for realizing sewage denitrification and dephosphorization and reclamation of phosphorus resource
CN210974184U (en) * 2019-08-21 2020-07-10 长沙理工大学 Recovery unit of phosphorus in sewage plant second grade play water

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102372353A (en) * 2011-08-03 2012-03-14 东华大学 Spiral-flow type crystal phosphorous removal reactor
CN110015814A (en) * 2019-04-23 2019-07-16 东南大学 A kind of synchronous device and method for realizing sewage denitrification and dephosphorization and reclamation of phosphorus resource
CN210974184U (en) * 2019-08-21 2020-07-10 长沙理工大学 Recovery unit of phosphorus in sewage plant second grade play water

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