A device and method for low-carbon and high-efficiency simultaneous denitrification and dephosphorization of sewage and phosphorus recovery

Abstract

The present invention relates to the technical field of sewage treatment, and in particular to a device and method for low-carbon and high-efficiency synchronous denitrification and phosphorus recovery of sewage. The method of the present invention realizes the coupling of short-range denitrification, anaerobic ammonia oxidation and biomineralization, and realizes the removal of nitrogen in sewage through short-range denitrification and anaerobic ammonia oxidation, and realizes the removal of phosphorus in sewage through biomineralization; while removing phosphorus, hydroxyapatite is obtained, and hydroxyapatite can be used as the core of granular sludge to ensure the stability of granular sludge, and an aerobic-anoxic-anaerobic microbial environment is formed on the granular sludge, which is conducive to the reduction of sludge; at the same time, the reaction equipment discharges sludge regularly, and the flocculent sludge and the core in the granular sludge can be separated by a dispersion device and a separation device, and the separated core can be utilized as a resource, and the separated flocculent sludge is concentrated and returned to the fermentation area, and the carbon source can be supplemented after fermentation to achieve sludge reduction.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a device and method for low-carbon and high-efficiency simultaneous denitrification and dephosphorization of sewage and phosphorus recovery. Background Art

[0002] With the increasing problems of eutrophication of water bodies and depletion of phosphate rock, biological denitrification, phosphorus removal and phosphorus recovery processes have been widely studied and applied. The demand for carbon sources in traditional biological denitrification and phosphorus removal processes not only limits the removal of total nitrogen and phosphorus in low-carbon-nitrogen ratio urban domestic sewage, but also has high operating costs. Traditional chemical precipitation phosphorus removal methods are not suitable for the removal and recovery of phosphorus in low-phosphorus concentration domestic sewage. The main challenge currently facing the treatment of low-carbon-nitrogen ratio urban domestic sewage is to achieve simultaneous denitrification, phosphorus removal and phosphorus recovery in an economical and efficient manner. Biomineralization, which is currently a research hotspot, can combine biological transformation and chemical precipitation, and has advantages such as energy saving and consumption reduction. If biomineralization is used to induce the formation of hydroxyapatite in the biological denitrification and phosphorus removal system of sewage, it can not only solve the problem of eutrophication of water bodies, but also achieve phosphorus recovery and resource utilization.

[0003] Short-cut denitrification coupled with anaerobic ammonium oxidation (ANAMMOX) is a popular, economical, and environmentally friendly wastewater denitrification process. Due to its carbon source requirements, it can be combined with in-situ fermentation technology. The fermentation products provide a carbon source for short-cut denitrification coupled with ANAMMOX, achieving deep denitrification, energy conservation, and resource utilization of excess sludge. Combining this with biomineralization for phosphorus removal can not only promote the original denitrification process, but also achieve phosphorus removal and recovery.

[0004] Based on the challenges and difficulties faced in urban domestic sewage treatment, the present invention combines short-range denitrification / anaerobic ammonium oxidation / in situ fermentation with biologically induced mineralized phosphorus recovery technology to propose a low-carbon and high-efficiency synchronous denitrification and phosphorus removal device and method. This not only promotes the denitrification and phosphorus removal capabilities of the sewage treatment system, but also achieves efficient phosphorus recovery, which has positive significance for urban domestic sewage treatment, environmental protection and comprehensive resource utilization. Summary of the Invention

[0005] The purpose of the present invention is to provide a device and method for low-carbon and high-efficiency simultaneous denitrification and dephosphorization of sewage and phosphorus recovery, so as to solve the problem that the existing denitrification and dephosphorization process is not convenient for phosphorus recovery.

[0006] To achieve the above-mentioned object, the present invention adopts the following technical solution: a device for low-carbon and high-efficiency simultaneous denitrification and phosphorus removal and phosphorus recovery in sewage, comprising a water inlet tank, a dosing tank, a reaction device, a dispersion device, a separation device and a sludge thickening tank;

[0007] The reaction equipment is provided with a fermentation area, a reaction area and a water outlet area in order from bottom to top;

[0008] The reaction zone is used for the simultaneous removal of nitrogen and phosphorus. The reaction zone is filled with annular fillers, and the bottom of the reaction zone is connected to the water inlet tank and the drug adding tank.

[0009] The bottom of the water outlet area is connected to the bottom of the fermentation area through a reflux pipe;

[0010] The bottom of the reaction zone is also provided with a mud discharge port, which is connected to the dispersion equipment, and the dispersion equipment is connected to the separation equipment;

[0011] The dispersion equipment is used to disperse the granular sludge discharged from the reaction zone to obtain flocculent sludge and cores;

[0012] The separation device is used to separate the obtained flocculent sludge from the core; the flocculent sludge separated by the separation device is introduced into the sludge concentration tank, and the sludge concentration tank is connected to the bottom of the fermentation area.

[0013] Furthermore, the water inlet tank includes a city sewage inlet tank and an industrial wastewater inlet tank. The city sewage inlet tank contains wastewater rich in COD, NH4 + -N wastewater, industrial wastewater inlet tank is rich in NO3 - -N wastewater, and the dosing box contains CaCl2 solution.

[0014] Furthermore, a flow partition is provided between the fermentation area and the reaction area, and a through hole is provided in the middle portion of the flow partition.

[0015] Furthermore, the dispersion equipment is an ultrasonic dispersion equipment, in which an ultrasonic vibration rod is installed; the separation equipment is a hydrocyclone, the top outlet of the hydrocyclone is a flocculent sludge outlet, and the top outlet is connected to the sludge concentration tank; the bottom outlet of the hydrocyclone is a core outlet, and phosphorus recovery is achieved through the bottom outlet.

[0016] The method for low-carbon and high-efficiency simultaneous denitrification and phosphorus removal and phosphorus recovery of sewage according to the above device comprises the following steps:

[0017] S1. Startup of reaction equipment

[0018] S11, inoculating mature anaerobic ammonium oxidation biofilm fillers and short-cut denitrification sludge into the reaction zone, and inoculating fermentation sludge into the fermentation zone;

[0019] S12, the water from the water inlet tank is distributed into the reaction equipment, a certain hydraulic retention time and a reflux ratio between the water outlet area and the fermentation area are maintained, and the reaction equipment is started.

[0020] S2. System operation

[0021] S21, maintaining the operating conditions in S1, adding reagents to the reaction equipment through the drug adding box;

[0022] S22, regularly discharging the sludge generated by the reaction equipment into the dispersion equipment;

[0023] S23, dispersing the sludge in a dispersion device to obtain flocculent sludge and cores, and passing the obtained flocculent sludge and cores into a membrane separation device;

[0024] S24, separating the floc sludge from the core in a membrane separation device to obtain the core, thereby recovering phosphorus; the obtained floc sludge enters a sludge thickening tank;

[0025] S25. Return the concentrated sludge at the bottom of the sludge thickening tank to the bottom of the fermentation zone of the reaction equipment.

[0026] Furthermore, in the S1, the sludge concentration in the reaction zone after inoculation is 3000-5000 mg / L, the filling ratio is 10-15%; the sludge concentration in the fermentation zone is 5500-6500 mg / L; the hydraulic retention time is 8-16 hours, the reflux ratio is 100-500%; the NH4 + -N concentration is 35~45mg / L, NO3 - The -N concentration is 35-45 mg / L. When the total nitrogen removal rate in the system is higher than 75% and maintained for more than 15 days, the reaction equipment is successfully started.

[0027] Furthermore, in the S2, control Ca 2+ and PO4 3- The mass concentration ratio is 2 to 5:1.

[0028] Furthermore, in the S2, the frequency of regular sludge discharge is 1 to 2 days / time. When discharging sludge, the reaction equipment stops feeding water, opens the sludge discharge port to discharge sludge, and controls the sludge concentration in the reaction zone after sludge discharge to be

[0029] 3000~3500mg / L.

[0030] Furthermore, in the S2, the frequency of the ultrasound is 20 to 28 kHz, the power is 65 W, and the action time is 5 to 10 minutes.

[0031] Furthermore, in the above-mentioned S2, the sludge concentration in the fermentation zone of the reaction equipment is controlled to be 5500-6500 mg / L by reflux of the sludge in the sludge thickening tank.

[0032] Beneficial effects of the present invention:

[0033] 1. While removing nitrogen, phosphorus and organic pollutants from sewage, it also realizes the recovery and resource utilization of phosphorus;

[0034] 2. The combination of short-cut denitrification, anaerobic ammonium oxidation and biomineralization for phosphorus removal breaks through the current situation where traditional short-cut denitrification coupled with anaerobic ammonium oxidation systems cannot remove phosphorus;

[0035] 3. The short doubling time of heterotrophic denitrifying microorganisms allows regular discharge of granular sludge from the reactor to achieve biomass stability in the reactor and continuous phosphorus removal and recovery;

[0036] 4. The separation of biomineralization phosphorus removal and anaerobic ammonium oxidation denitrification reaction makes it possible to recover phosphorus from sludge without adversely affecting anaerobic ammonium oxidation, thus ensuring the stable progress of anaerobic ammonium oxidation reaction.

[0037] 5. Dispersion equipment and separation equipment can more effectively achieve the classification of organic sludge and inorganic hydroxyapatite particles;

[0038] 6. The inorganic core separated from the granular sludge is mainly composed of hydroxyapatite, which is conducive to the efficient recovery of phosphorus; the flocculent sludge containing a large amount of organic matter separated from the granular sludge can produce volatile fatty acids through sludge fermentation to provide a carbon source for denitrification, thereby achieving the reduction and resource utilization of residual sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the structural flow of the reaction equipment of the present invention.

[0040] The names corresponding to the marks in the figure are:

[0041] 1. Municipal sewage inlet tank; 1.1. Delivery pump A; 2. Industrial wastewater inlet tank; 2.1. Delivery pump B; 3. Dosing tank; 3.1. Delivery pump C; 4. Reaction equipment; 4.1. Annular filler; 4.2. Mud discharge port; 4.3. Return water inlet; 4.4. Water outlet; 4.5. Water inlet; 4.6. Return pump; 4.7. Fermentation area; 4.8. Baffle; 5. Dispersion equipment; 5.1. Ultrasonic vibrating rod; 6. Separation equipment; 6.1. Feed inlet A; 6.2. Top outlet; 6.3. Bottom outlet; 7. Sludge thickening tank; 7.1. Feed inlet B; 7.2 Stirring device; 7.3. Delivery pump D. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0043] The principle of the present invention is:

[0044] In the method of the present invention, urban domestic sewage and NO3-rich - The industrial wastewater is fed into the reaction zone of the reaction equipment together with the influent. The denitrifying microorganisms in the center of the reaction zone work to convert NO3 --N (nitrate nitrogen) is converted to NO2 - -N (nitrite nitrogen), generated NO2 - -N and NH4 in urban domestic sewage + -N is used as a reaction substrate by the microorganisms in the annular filler (polyethylene filler) attached to the inner wall of the reaction equipment to carry out anaerobic ammonia oxidation reaction to achieve NO2 - -N and NH4 + -N synchronous removal.

[0045] In addition, CaCl2 is added to the reaction equipment through the dosing box. 2+ With PO4 3- The two materials combine to form hydroxyapatite, which can remove phosphorus. At the same time, hydroxyapatite can serve as the core of granular sludge to ensure the stability of granular sludge, and form an aerobic-anoxic-anaerobic microbial environment on the granular sludge, which helps to reduce the amount of sludge. A fermentation area is set at the bottom of the reaction equipment. The fermentation action can supplement the lack of carbon source in domestic sewage and achieve the effect of sludge reduction.

[0046] The granular sludge is discharged from the reaction equipment in a regular manner, and the discharged granular sludge enters the dispersion equipment and separation equipment in turn to separate the high-content and high-purity inorganic hydroxyapatite cores and high-organic matter sludge in the granular sludge; the separated inorganic hydroxyapatite cores can be used as fertilizers in the agricultural field after further purification, and can also be used as adsorbents to remove dyes, emerging pollutants and heavy metals, thereby achieving the purpose of phosphorus recovery and resource utilization; the separated high-organic matter sludge enters the sludge thickening tank, and the concentrated sludge is returned to the fermentation area of ​​the reactor for fermentation to produce volatile fatty acids to supplement the carbon source for the reactor.

[0047] The method of the present invention can achieve synchronous deep denitrification and phosphorus removal of domestic sewage and industrial wastewater, as well as phosphorus recovery and resource utilization, and reduction and resource utilization of excess sludge.

[0048] Example 1

[0049] like Figure 1 As shown, the device for simultaneous nitrogen removal, phosphorus removal and phosphorus recovery in this embodiment includes a reaction device, which is provided with a fermentation area, a reaction area and a water outlet area in sequence from bottom to top. A flow partition is provided between the fermentation area and the reaction area, a through hole is provided in the center of the flow partition, and the fermentation area and the reaction area are connected through the through hole. The reaction area is filled with an annular filler, a reflux pipe is provided between the bottom of the water outlet area and the bottom of the fermentation area, and a reflux pump is installed on the reflux pipe; a water outlet is provided above the water outlet area.

[0050] A water inlet is provided at the bottom of the reaction zone, which is connected to the water inlet pipe, and the water inlet pipe is respectively connected to the municipal sewage inlet tank, the industrial wastewater inlet tank and the CaCl2 dosing box; a delivery pump A is provided between the municipal sewage inlet tank and the water inlet pipe, a delivery pump B is provided between the industrial wastewater inlet tank and the water inlet pipe, and a delivery pump C is provided between the CaCl2 dosing box and the water inlet pipe.

[0051] A mud discharge port is provided at the bottom of the reaction zone, and the mud discharge port is connected to the dispersion equipment. In this embodiment, the dispersion equipment is an ultrasonic dispersion equipment, and a plurality of ultrasonic vibration rods are installed in the ultrasonic dispersion equipment. The outlet of the ultrasonic dispersion equipment is connected to the separation equipment. In this embodiment, the separation equipment is a hydrocyclone, and the outlet of the ultrasonic dispersion equipment is connected to the feed port A of the hydrocyclone. A bottom outlet is provided below the hydrocyclone, and a top outlet is provided above the hydrocyclone. The top outlet is connected to the feed port B of the sludge thickening tank. A stirring device is provided in the sludge thickening tank, and a conveying pipe is provided at the bottom of the sludge thickening tank. The conveying pipe is connected to the bottom of the fermentation zone, and a conveying pump D is installed on the conveying pipe.

[0052] Based on the above reaction device, the method of the present invention is adopted to treat urban sewage and industrial sewage.

[0053] In this embodiment, the specific test water is simulated urban sewage and industrial sewage; the quality of domestic sewage is as follows: COD concentration is 150-250 mg / L, NH4 + -N concentration is 60mg / L, NO3 - -N≤0.5mg / L, P=5mg / L, CaCl2·2H2O=14mg / L, MgSO4·7H2O=90mg / L; the water quality of industrial wastewater is as follows: NO3 - -N=120mg / L, P=33mg / l, CaCl2·2H2O=44mg / L.

[0054] In this embodiment, simulated urban sewage and simulated industrial sewage are added to the reaction equipment in a ratio of 2:1.

[0055] Test system such as Figure 1 As shown, each reactor is made of organic glass, and the effective volume of the reaction equipment is 25L.

[0056] The specific operation operations are as follows:

[0057] S1. Start the system

[0058] The reaction equipment is filled with annular polyethylene filler with a filler filling ratio of 12%; mature anaerobic ammonia oxidation biofilm filler and short-cut denitrification sludge are directly inoculated into the reaction zone of the reaction equipment, and the sludge concentration in the reaction zone after inoculation is 4000 mg / L; fermentation sludge is inoculated in the fermentation zone, and the sludge concentration in the fermentation zone after inoculation is 6000 mg / L.

[0059] The reaction equipment was operated under the conditions of a hydraulic retention time (HRT) of 14h and a sludge return ratio of 3, and the total nitrogen content in the water was detected. When the total nitrogen removal rate in the reaction equipment was higher than 75% and maintained for more than 15 days, the reaction equipment was successfully started.

[0060] The runtime adjustments are as follows:

[0061] a. Under the above operating conditions, add CaCl2 reagent to the reaction equipment so that Ca 2+ and PO4 3- The mass concentration ratio of calcium ions to phosphate is 3:1; under the condition of adding calcium ions, calcium ions and phosphates form hydroxyapatite, and the formed hydroxyapatite can serve as the core of granular sludge;

[0062] b. Regularly discharge sludge from the reaction equipment at a frequency of once a day. Stop water inlet during sludge discharge to ensure that the sludge concentration in the reaction zone after sludge discharge is not less than 3000 mg / L. The granular sludge discharged from the sludge discharge port of the reaction equipment enters the sludge ultrasonic dispersion equipment;

[0063] c. The granular sludge is dispersed in an ultrasonic dispersion device with an ultrasonic frequency of 25KHz, a power of 65W, and an action time of 8 minutes. The ultrasonicated sludge is pumped into a hydrocyclone, which uses centrifugal force to separate the hydroxyapatite cores and high-organic floc sludge in the granular sludge. The separated hydroxyapatite cores are discharged from the bottom outlet; the floc sludge is discharged from the top outlet and then enters the sludge thickening tank for concentration. The concentrated sludge is pumped into the fermentation zone of the reaction equipment through a delivery pump D to ensure that the sludge concentration in the fermentation zone is stable between 5500 and 6500 mg / L.

[0064] The test results show that after the operation is stable, the final effluent COD of the reactor is 30-50 mg / L, NH4 + -N<3mg / L, NO2 - -N<1mg / L, NO3 - -N<3mg / L, P<0.5mg / L; after material balance, the total nitrogen removal rate is over 90%, the phosphorus removal rate is over 95%, and the phosphorus recovery rate is 40-60%.

[0065] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. A device for low-carbon and high-efficiency simultaneous denitrification and phosphorus removal from sewage and phosphorus recovery, characterized by: Including water inlet tank, dosing tank, reaction equipment, dispersion equipment, separation equipment and sludge thickening tank; The water inlet tank includes a city sewage inlet tank and an industrial wastewater inlet tank. The city sewage inlet tank contains water rich in COD and NH4 + -N wastewater, industrial wastewater inlet tank is rich in NO3 - -N wastewater, the dosing box contains CaCl2 solution; The reaction equipment is provided with a fermentation zone, a reaction zone and a water outlet zone in order from bottom to top; the reaction zone is inoculated with mature anaerobic ammonia oxidation biofilm filler and short-range denitrification sludge, and the fermentation zone is inoculated with fermentation sludge; a flow partition is provided between the fermentation zone and the reaction zone, and a through hole is provided in the middle part of the flow partition; The reaction zone is used for the simultaneous removal of nitrogen and phosphorus. The reaction zone is filled with annular fillers, and the bottom of the reaction zone is connected to the water inlet tank and the dosing tank. Granular sludge with hydroxyapatite as the core is formed in the reaction zone. The bottom of the water outlet area is connected to the bottom of the fermentation area through a reflux pipe; The bottom of the reaction zone is also provided with a mud discharge port, which is connected to the dispersion equipment, and the dispersion equipment is connected to the separation equipment; The dispersion equipment is used to disperse the granular sludge discharged from the reaction zone to obtain flocculent sludge and cores; The separation equipment is used to separate the obtained flocculent sludge from the core; The flocculent sludge obtained by separation equipment is introduced into the sludge thickening tank, and the sludge thickening tank is connected to the bottom of the fermentation area.

2. The device for low-carbon and high-efficiency simultaneous denitrification and phosphorus removal and phosphorus recovery of sewage according to claim 1, characterized in that: The dispersing device is an ultrasonic dispersing device, in which an ultrasonic vibrating rod is installed; the separating device is a hydrocyclone, the top outlet of the hydrocyclone is a flocculent sludge outlet, and the top outlet is connected to the sludge concentration tank; the bottom outlet of the hydrocyclone is a core outlet, and phosphorus recovery is achieved through the bottom outlet.

3. The method for low-carbon and high-efficiency simultaneous denitrification and phosphorus removal and phosphorus recovery of sewage according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Startup of reaction equipment S11, inoculating mature anaerobic ammonium oxidation biofilm fillers and short-cut denitrification sludge into the reaction zone, and inoculating fermentation sludge into the fermentation zone; S12, the water inlet tank is distributed into the reaction equipment, a certain hydraulic retention time and a reflux ratio between the water outlet area and the fermentation area are maintained, and the reaction equipment is started; S2. System operation S21, maintaining the operating conditions in S1, adding reagents to the reaction equipment through the drug adding box; S22, regularly discharging the sludge generated by the reaction equipment into the dispersion equipment; S23, dispersing the sludge in a dispersing device to obtain flocculent sludge and cores, and passing the obtained flocculent sludge and cores into a separation device; S24, separating the floc sludge from the core in a separation device to obtain the core, thereby recovering phosphorus; the obtained floc sludge enters a sludge thickening tank; S25. Return the concentrated sludge at the bottom of the sludge thickening tank to the bottom of the fermentation zone of the reaction equipment.

4. The method for low-carbon and high-efficiency simultaneous denitrification and phosphorus removal and phosphorus recovery in sewage according to claim 3, characterized in that: In the S1, the sludge concentration in the reaction zone after inoculation is 3000~5000mg / L, the filling ratio of the ring filler is 10~15%; the sludge concentration in the fermentation zone is 5500~6500mg / L; in the reaction equipment, the hydraulic retention time is 8~16h, the sludge return ratio is 100~500%; NH4 + -N concentration is 35~45mg / L, NO3 - The -N concentration is 35~45mg / L. When the total nitrogen removal rate in the system is higher than 75% and maintained for more than 15 days, the reaction equipment is successfully started.

5. The method for low-carbon and high-efficiency simultaneous denitrification and phosphorus removal and phosphorus recovery in sewage according to claim 3, characterized in that: In the S21, CaCl2 reagent is added to the reaction equipment to control Ca 2+ and PO4 3- The mass concentration ratio is 2~5:

1.

6. The method for low-carbon and high-efficiency simultaneous denitrification and phosphorus removal and phosphorus recovery in sewage according to claim 3, characterized in that: In the S2, the frequency of regular sludge discharge is 1 to 2 days / time. During sludge discharge, the reaction equipment stops feeding water, the sludge discharge port is opened to discharge sludge, and the sludge concentration in the reaction zone after sludge discharge is controlled to be 3000 to 3500 mg / L.

7. The method for low-carbon and high-efficiency simultaneous denitrification and phosphorus removal and phosphorus recovery in sewage according to claim 3, characterized in that: In the above-mentioned S2, the dispersing device is an ultrasonic dispersing device, the ultrasonic frequency is 20-28 kHz, the power is 65 W, and the action time is 5-10 min.

8. The method for low-carbon and high-efficiency simultaneous denitrification and phosphorus removal and phosphorus recovery in sewage according to claim 3, characterized in that: In the above-mentioned S2, the sludge concentration in the fermentation zone of the reaction equipment is controlled to be 5500-6500 mg / L by reflux of the sludge in the sludge thickening tank.

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