Induced crystallization fluidized bed apparatus and method for high calcium high ammonia nitrogen wastewater treatment

Abstract

The application discloses a kind of induced crystallization fluidized bed equipment and method for high calcium high ammonia nitrogen wastewater treatment, including fluidized bed main reactor, control system, ammonia nitrogen concentration monitoring module and calcium ion concentration detection module;The side of fluidized bed main reactor is provided with drainage pipe and seed discharge pipe arranged from top to bottom;Drainage pipe is provided with first valve body, seed discharge pipe is provided with second valve body, first valve body and second valve body are electrically connected with control system;Ammonia nitrogen concentration detection module and calcium ion concentration detection module are arranged at the top of fluidized bed main reactor, and are electrically connected with control system, are respectively used to detect the ammonia nitrogen concentration and calcium ion concentration of processing water and feedback to control system, to control the on-off of first valve body and second valve body and adjust the discharge frequency of seed.The fluidized bed equipment cooperates with control system through ammonia nitrogen concentration monitoring module and calcium ion concentration monitoring module, and dynamically adjusts seed discharge frequency and discharge timing, prolongs seed residence time.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment technology, and in particular to an induced crystallization fluidized bed device and method for treating high-calcium and high-ammonia-nitrogen wastewater. Background Technology

[0002] The electrolytic manganese production process generates a large amount of wastewater containing calcium, sulfate, and ammonia nitrogen. In the advanced treatment and reuse of this wastewater, the calcium sulfate scale layer formed by the combination of high concentrations of calcium and sulfate ions is a major obstacle to the application of membrane separation technology. Chemical precipitation methods consume large amounts of reagents and produce high sludge yields; ion exchange methods require frequent regeneration and have high operating costs; scale inhibitors can only delay scaling but cannot fundamentally remove hardness.

[0003] Induced crystallization fluidized bed technology provides a heterogeneous nucleation surface for calcium sulfate crystallization by adding seed crystals, converting calcium ions in water into dense gypsum crystal particles. It offers advantages such as low sludge production and the ability to recycle the products. However, when treating wastewater with high ammonia nitrogen levels, ammonia nitrogen significantly inhibits calcium sulfate crystal growth, leading to a decrease in the growth rate of the seed crystal surface. If a fixed-period seed crystal discharge method is used, excessively frequent seed crystal replacement and bed loss can easily occur during periods of high ammonia nitrogen concentration. Summary of the Invention

[0004] The main objective of this invention is to provide an induced crystallization fluidized bed device and method for treating high-calcium and high-ammonia-nitrogen wastewater. This invention aims to solve the problem that existing induced crystallization fluidized beds, which use a fixed-cycle seed discharge operation, are prone to excessive seed renewal and bed loss during periods of high ammonia-nitrogen concentration.

[0005] To achieve the above objectives, this invention proposes an induced crystallization fluidized bed device for treating high-calcium and high-ammonia-nitrogen wastewater, comprising a fluidized bed main reactor, a control system, an ammonia-nitrogen concentration monitoring module, and a calcium ion concentration detection module. One side of the fluidized bed main reactor is provided with a drain pipe and a seed discharge pipe arranged from top to bottom, and the bottom of the other side is provided with a water inlet assembly. The drain pipe is equipped with a first valve body, and the seed discharge pipe is equipped with a second valve body; both the first and second valve bodies are electrically connected to the control system. The ammonia-nitrogen concentration detection module and the calcium ion concentration detection module are both located at the top of the fluidized bed main reactor and are electrically connected to the control system, respectively used to detect the ammonia-nitrogen concentration and calcium ion concentration of the treated water and feed them back to the control system to control the opening and closing of the first and second valve bodies and adjust the seed discharge frequency.

[0006] Preferably, the distance between the seed discharge pipe and the bottom of the fluidized bed main reactor is 0.8m to 1.0m, and is higher than the initial seed stacking height.

[0007] Preferably, the top of the fluidized bed main reactor is provided with a seed inlet for initial seeding or replenishment of seed crystals.

[0008] Preferably, the height-to-diameter ratio of the fluidized bed main reactor is 0.5:1 to 0.8:1.

[0009] Preferably, an observation window is also provided on one side of the fluidized bed main reactor.

[0010] Preferably, the water inlet assembly includes a water inlet pump, a water inlet pipe, and a water distributor. One end of the water inlet pipe is connected to a water storage tank via the water inlet pump, and the other end is connected to the water distributor. The opening of the water distributor is oriented towards the inner bottom surface of the fluidized bed main reactor.

[0011] Preferably, the aperture of the water distributor is 8-12 mm, and the spacing between adjacent apertures is 60-100 mm.

[0012] Preferably, the fluidized bed main reactor is equipped with a stirring device.

[0013] Another aspect of the present invention provides a method for use with the above-described device, comprising the following steps: S1: Loading seed crystals: Seed crystals are added to the fluidized bed main reactor, with an initial stacking height of 0.4m~0.6m; S2: Water flow operation, a certain amount of water to be treated is introduced into the fluidized bed main reactor, and the bed expansion ratio is controlled at 1.2~1.8. At the same time, the mixture is stirred evenly for 12~20 min and then allowed to stand for 8h~12h. S3: Crystallization removal. The ammonia nitrogen concentration and calcium ion concentration in the upper layer of the fluidized bed main reactor are monitored at all times by the ammonia nitrogen concentration monitoring module and the calcium ion concentration monitoring module. When the ammonia nitrogen concentration or calcium ion concentration is higher than the set value, the opening frequency of the second valve is adjusted, and the second valve is opened after the set reaction time to discharge the seed crystals. When the water level in the fluidized bed main reactor is higher than the set value, the first valve is opened to discharge the treated water.

[0014] Preferably, before water is introduced into operation, the pH value of the water to be treated is adjusted to be between 6.5 and 7.5.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The fluidized bed equipment dynamically adjusts the seed discharge frequency and timing through the cooperation of the ammonia nitrogen concentration monitoring module and the calcium ion concentration monitoring module with the control system. When the ammonia nitrogen concentration or calcium ion concentration is higher than the set value and the crystallization rate is inhibited, the control system automatically reduces the discharge frequency and prolongs the seed residence time. (2) Water is fed into the fluidized bed reactor through the water inlet assembly to make the water flow distribution uniform and the seed crystal fluidized state; (3) Monitor the liquid level height through the liquid level gauge. When the liquid level is higher than the set value, drain the treated water through the drain pipe to ensure that there is sufficient reaction space in the fluidized bed reactor. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of an induced crystallization fluidized bed device for treating high-calcium and high-ammonia nitrogen wastewater according to the present invention; Figure 2 This is a schematic diagram of the principle flow of an induced crystallization fluidized bed device for treating high-calcium and high-ammonia nitrogen wastewater according to the present invention; Figure 3 This is a flowchart illustrating the method of using an induced crystallization fluidized bed device for treating high-calcium and high-ammonia-nitrogen wastewater according to the present invention.

[0018] In the attached diagram, 1-fluidized bed main reactor, 11-seed inlet, 12-observation window, 2-control system, 3-ammonia nitrogen concentration monitoring module, 4-calcium ion concentration detection module, 5-drainage pipe, 51-first valve body, 6-seed discharge pipe, 61-second valve body, 7-water inlet assembly, 71-water inlet pump, 72-water inlet pipe, 73-water distributor, 8-stirring device, and 9-level gauge. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0021] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0022] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0023] Please see Figure 1 and Figure 2 As shown, this invention proposes an induced crystallization fluidized bed device for treating high-calcium and high-ammonia-nitrogen wastewater, including a fluidized bed main reactor 1, a control system 2, an ammonia-nitrogen concentration monitoring module 3, and a calcium ion concentration detection module 4. One side of the fluidized bed main reactor 1 is provided with a drain pipe 5 and a seed discharge pipe 6 arranged from top to bottom, and the bottom of the other side is provided with a water inlet assembly 7. The drain pipe 5 is provided with a first valve body 51, and the seed discharge pipe 6 is provided with a second valve body 61. Both the first valve body 51 and the second valve body 61 are electrically connected to the control system 2. The ammonia-nitrogen concentration detection module and the calcium ion concentration detection module 4 are both located at the top of the fluidized bed main reactor 1 and are electrically connected to the control system 2. They are used to detect the ammonia-nitrogen concentration and calcium ion concentration of the treated water and feed them back to the control system 2 to control the opening and closing of the first valve body 51 and the second valve body 61 and to adjust the seed discharge frequency. The ammonia nitrogen concentration detection module uses a bioelectrochemical reaction to determine the ammonia nitrogen concentration in the water. It includes a probe and a data processing unit. The probe is used to monitor the ammonia nitrogen concentration in the upper layer of water within the fluidized bed main reactor 1 in real time and feeds it back to the data processing unit and control system 2. The calcium ion concentration detection module 4 uses a DP-8000CA analyzer. The control system 2 includes a processing terminal and a PLC controller.

[0024] In an optional embodiment, the distance between the seed discharge pipe 6 and the bottom of the fluidized bed main reactor 1 is 0.8m to 1.0m, and is higher than the initial seed accumulation height. This avoids the discharge of unfluidized seeds during the discharge of grown seeds.

[0025] In an optional embodiment, the top of the fluidized bed main reactor 1 is provided with a seed inlet 11 for initial seeding or replenishment of seed crystals. After some of the grown seed crystals are discharged, fresh seed crystals of the same mass can be added to the fluidized bed main reactor 1 through the seed inlet 11 to maintain the stability of the bed height.

[0026] In an optional embodiment, the height-to-diameter ratio of the fluidized bed main reactor 1 is 0.5:1 to 0.8:1. Within this height-to-diameter ratio range, the water flow distribution is uniform, and the seed crystal fluidization state is stable. This also ensures sufficient sedimentation and separation space without making the equipment excessively tall.

[0027] In an optional embodiment, an observation window 12 is also provided on one side of the fluidized bed main reactor 1. At least two observation windows 12 are provided, for manual observation of the liquid level and seed crystal height, respectively. In actual use, the fluidized bed main reactor 1 is also equipped with a level gauge 9 to monitor changes in the liquid level in the fluidized bed. The level gauge 9 is electrically connected to the control system 2. In addition to using the ammonia nitrogen concentration monitoring module 3 and the level gauge 9, the operator can also manually determine the timing of discharge.

[0028] In an optional embodiment, the water inlet assembly 7 includes a water inlet pump 71, a water inlet pipe 72, and a water distributor 73. One end of the water inlet pipe 72 is connected to a water storage tank via the water inlet pump 71, and the other end is connected to the water distributor 73. The water to be treated is uniformly introduced into the fluidized bed main reactor 1 through the water distributor 73. Simultaneously, the stirring device 8 installed in the fluidized bed main reactor 1 ensures that the water to be treated is in full contact with the seed crystals. The opening of the water distributor 73 is oriented towards the inner bottom surface of the fluidized bed main reactor 1 to prevent seed crystal particles from clogging the water distribution holes.

[0029] In an optional embodiment, the opening diameter of the water distributor 73 is 8~12 mm, and the spacing between adjacent openings is 60~100 mm.

[0030] The present invention also proposes a method for use in the above-mentioned equipment. The specific structure of the induced crystallization fluidized bed equipment for treating high-calcium and high-ammonia nitrogen wastewater is as described in the above embodiments. Since the induced crystallization fluidized bed equipment for treating high-calcium and high-ammonia nitrogen wastewater adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0031] like Figure 3 As shown, another aspect of the present invention provides a method for use in the above-described device, comprising the following steps: S1: Filling with seed crystals: Seed crystals are added to the fluidized bed main reactor 1, with an initial stacking height of 0.4m~0.6m; S2: Water flow operation: A fixed amount of water to be treated is introduced into the fluidized bed main reactor 1 at an upward flow rate of 0.8~2.0 mm / s, so that the seed crystals are in a fluidized state in the fluidized bed reactor. The bed expansion ratio is controlled at 1.2~1.8, which can ensure that the seed crystals are fully fluidized and avoid excessive flow rate leading to seed crystal wear and loss. At the same time, the mixture is stirred evenly for 12~20 min and then allowed to stand for 8h~12h. S3: Crystallization removal. The ammonia nitrogen concentration and calcium ion concentration in the upper layer water of the fluidized bed main reactor 1 are constantly monitored by the ammonia nitrogen concentration monitoring module 3 and the calcium ion concentration monitoring module. When the ammonia nitrogen concentration or calcium ion concentration is higher than the set value, the opening frequency of the second valve 61 is adjusted, and the second valve 61 is opened after the set reaction time to discharge the seed crystals. When the water level in the fluidized bed main reactor 1 is higher than the set value, the first valve 51 is opened to discharge the treated water. That is, when the ammonia nitrogen concentration increases and the crystallization rate is inhibited, the control system 2 automatically reduces the discharge frequency and prolongs the seed crystal residence time.

[0032] In an optional embodiment, the pH of the water to be treated is adjusted to between 6.5 and 7.5 before water flow operation to reduce the inhibitory effect of free ammonia on the crystallization process.

[0033] Example 1 This embodiment provides an induced crystallization fluidized bed device for treating electrolytic manganese wastewater.

[0034] The main body of the fluidized bed reactor is made of carbon steel lined with rubber, with a lining thickness of 3 mm. The water distributor 73 is located inside the main fluidized bed reactor 1, 0.3 m from the bottom. The water distributor 73 has 10 mm orifice diameters, with the orifices pointing vertically downwards and an 80 mm spacing between adjacent orifices. The seed crystal inlet 11 is located 1.5 m from the bottom of the main fluidized bed reactor 1. The seed crystal outlet 6 is located 0.5 m from the bottom of the main fluidized bed reactor 1.

[0035] The equipment in this embodiment is used to treat wastewater from an electrolytic manganese plant, with a treatment capacity of 2000 m³ / d. Natural calcium sulfate dihydrate seed crystals with a particle size of 48~150 μm are added to the fluidized bed main reactor 1 through the seed inlet 11, with an initial packing height of 0.4m~0.6m. The influent water quality is as follows: calcium ion concentration 249~352 mg / L, sulfate concentration 4120~4680 mg / L, ammonia nitrogen concentration 1328~2150 mg / L, and pH value 5.1~8.3.

[0036] The operation process is as follows: First, 20.3 tons of natural calcium sulfate dihydrate seed crystals with a particle size of 75~150 μm were added into the fluidized bed reactor through seed crystal addition port 11, with an initial stacking height of 0.6 m.

[0037] Before starting the influent, the pH of the water to be treated was adjusted to 7.0 using NaOH solution. The influent flow rate was controlled at 83.3 m³ / h, the upflow velocity at 1.46 mm / s, and the bed expansion ratio was kept stable at 1.3.

[0038] During operation, the ammonia nitrogen concentration monitoring module 3 detects the ammonia nitrogen concentration in real time. The control system 2 adjusts the opening frequency of the second valve 61 according to the changes in ammonia nitrogen concentration. When the ammonia nitrogen concentration is higher than 2000 mg / L, the opening frequency of the second valve 61 is adjusted from once every 8 hours to once every 12 hours, and about 650 kg of grown seed crystals are discharged. When the calcium ion concentration is lower than 200 mg / L, the control system 2 appropriately reduces the discharge frequency.

[0039] Simultaneously, an equal amount of fresh seed crystals are added through seed crystal inlet 11. The discharged seed crystals are dewatered by a plate and frame filter press to obtain a gypsum filter cake with a moisture content of 15%. The purity of the by-product gypsum can reach over 85%, and it can be directly sold as a building material raw material. After 60 days of continuous operation, the calcium ion concentration in the effluent remained stable at 195~278 mg / L, with an average removal rate of 55.1%. The subsequent chemical cleaning cycle of the reverse osmosis system was extended from 9 days without pretreatment to 50 days.

[0040] Example 2 The difference between Example 2 and Example 1 is that the same equipment was used to treat electrolytic manganese wastewater of the same quality, and the upward flow velocity was adjusted to 1.2 mm / s. The operating results were basically the same as in Example 1, with an average calcium ion removal rate of 53.8% in the effluent.

[0041] Example 3 The difference between Example 3 and Example 1 is that, when using the same equipment to treat electrolytic manganese wastewater of the same quality, the upward flow velocity is adjusted to 1.8 mm / s. Table 1 below shows the influent and effluent Mn content of Examples 1-3 and Control Groups 1 and 2. 2+ NH3-N and Ca 2+ Concentration change data: Table 1. Concentration data of various substances in the examples and control group Examples 1-3 show that the equipment of the present invention can achieve stable hardening effect under different specifications and has good engineering adaptability; and the hardening effect is better than the existing process.

[0042] In summary, this fluidized bed reactor dynamically adjusts the seed crystal discharge frequency and timing through the cooperation of the ammonia nitrogen concentration monitoring module 3 and the calcium ion concentration monitoring module with the control system 2. When the ammonia nitrogen concentration or calcium ion concentration is higher than the set value and the crystallization rate is inhibited, the control system 2 automatically reduces the discharge frequency and extends the seed crystal residence time. Water is supplied to the fluidized bed reactor through the water inlet component 7, ensuring uniform water flow and a fluidized seed crystal state. The liquid level is monitored by the level gauge 9, and when the liquid level is higher than the set value, the treated water is discharged through the drain pipe 5 to ensure sufficient reaction space within the fluidized bed reactor.

[0043] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An induced crystallization fluidized bed device for treating high-calcium and high-ammonia nitrogen wastewater, characterized in that, The system includes a fluidized bed main reactor, a control system, an ammonia nitrogen concentration monitoring module, and a calcium ion concentration detection module. One side of the fluidized bed main reactor has a drain pipe and a seed discharge pipe arranged from top to bottom, while the bottom of the other side has a water inlet assembly. The drain pipe is equipped with a first valve body, and the seed discharge pipe is equipped with a second valve body. Both the first and second valve bodies are electrically connected to the control system. The ammonia nitrogen concentration detection module and the calcium ion concentration detection module are both located at the top of the fluidized bed main reactor and are electrically connected to the control system. They are used to detect the ammonia nitrogen concentration and calcium ion concentration of the treated water, respectively, and feed this information back to the control system to control the opening and closing of the first and second valve bodies and to adjust the seed discharge frequency.

2. The induced crystallization fluidized bed equipment for treating high-calcium and high-ammonia nitrogen wastewater according to claim 1, characterized in that, The distance between the seed discharge pipe and the bottom of the fluidized bed main reactor is 0.8m to 1.0m, and is higher than the initial seed stacking height.

3. The fluidized bed device for inducing crystallization in the treatment of high-calcium and high-ammonia nitrogen wastewater according to claim 1, characterized in that, The top of the fluidized bed main reactor is provided with a seed inlet for initial seeding or replenishment of seed crystals.

4. The induced crystallization fluidized bed equipment for treating high-calcium and high-ammonia nitrogen wastewater according to claim 1, characterized in that, The height-to-diameter ratio of the fluidized bed main reactor is 0.5:1 to 0.8:

1.

5. The fluidized bed device for inducing crystallization in the treatment of high-calcium and high-ammonia nitrogen wastewater according to claim 1, characterized in that, An observation window is also provided on one side of the fluidized bed main reactor.

6. The fluidized bed device for inducing crystallization in the treatment of high-calcium and high-ammonia nitrogen wastewater according to claim 1, characterized in that, The water inlet assembly includes a water inlet pump, a water inlet pipe, and a water distributor. One end of the water inlet pipe is connected to a water storage tank via the water inlet pump, and the other end is connected to the water distributor. The opening of the water distributor faces the inner bottom surface of the fluidized bed main reactor.

7. The fluidized bed device for inducing crystallization in the treatment of high-calcium and high-ammonia nitrogen wastewater according to claim 6, characterized in that, The opening diameter of the water distributor is 8~12 mm, and the spacing between adjacent openings is 60~100 mm.

8. The fluidized bed device for inducing crystallization in the treatment of high-calcium and high-ammonia nitrogen wastewater according to claim 1, characterized in that, The fluidized bed main reactor is equipped with a stirring device.

9. A method for inducing crystallization in the treatment of high-calcium and high-ammonia nitrogen wastewater, characterized in that, Using the induced crystallization fluidized bed equipment for treating high-calcium and high-ammonia nitrogen wastewater according to any one of claims 1 to 7 includes the following steps: S1: Loading seed crystals: Seed crystals are added to the fluidized bed main reactor, with an initial stacking height of 0.4m~0.6m; S2: Water flow operation, a certain amount of water to be treated is introduced into the fluidized bed main reactor, and the bed expansion ratio is controlled at 1.2~1.

8. At the same time, the mixture is stirred evenly for 12~20 min and then allowed to stand for 8h~12h. S3: Crystallization removal. The ammonia nitrogen concentration and calcium ion concentration in the upper layer of the fluidized bed main reactor are monitored at all times by the ammonia nitrogen concentration monitoring module and the calcium ion concentration monitoring module. When the ammonia nitrogen concentration or calcium ion concentration is higher than the set value, the opening frequency of the second valve is adjusted, and the second valve is opened after the set reaction time to discharge the seed crystals. When the water level in the fluidized bed main reactor is higher than the set value, the first valve is opened to discharge the treated water.

10. The method for inducing crystallization in the treatment of high-calcium and high-ammonia nitrogen wastewater according to claim 9, characterized in that, Before the water is put into operation, adjust the pH value of the water to be treated to be between 6.5 and 7.5.

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