Circulating water and blow-down water recycling treatment system

Abstract

The invention discloses a circulating water blow-off water reuse treatment system, and relates to the field of circulating cooling water treatment, the system comprises: an induced crystallization unit, which is used for carrying out primary treatment on circulating water blow-off water through an induced crystallization fluidized bed reactor to remove hardness ions in water; the ceramic membrane filtering unit is used for carrying out secondary treatment on the primarily treated water by utilizing a ceramic membrane device and removing residual hardness ions, organic matters and suspended matters in the water; and the nanofiltration membrane unit is used for performing tertiary treatment on the water by utilizing a nanofiltration membrane according to the secondary treatment result to remove salt and organic matters in the water. According to the method, induced crystallization, ceramic membrane and nanofiltration membrane technologies are combined to cooperatively treat the circulating water and the blow-down water, so that the operation mode of simplifying the process, reducing the energy consumption and prolonging the backwashing period is realized, the dosage of chemicals and the generation of sludge are reduced, and the water recovery rate is also improved, so that the hardness is removed, and the calcium resource recovery is realized.

Description

Technical Field

[0001] This invention relates to the field of circulating cooling water treatment, and more specifically, to a circulating water wastewater reuse treatment system. Background Technology

[0002] Circulating cooling water systems are widely used in industries such as power, chemical, and metallurgy. During operation, evaporation and concentration lead to a gradual increase in salt concentration and hardness ion concentration, such as calcium and magnesium. These ions readily react with carbonate and sulfate anions to form insoluble salts like calcium carbonate and calcium sulfate, resulting in scale that adheres to the surfaces of pipes and heat exchangers, affecting heat transfer efficiency and safe operation. Furthermore, the continuous accumulation of salt increases the risk of corrosion. In addition, some circulating water contains significant amounts of organic matter, which easily breeds microorganisms, forming biological slime that adheres to equipment surfaces. This not only reduces heat exchange efficiency but can also cause blockages, further exacerbating corrosion. Therefore, to ensure stable system operation, it is typically necessary to periodically discharge a portion of the high-concentration circulating water (i.e., wastewater) and replenish it with fresh water to control the salt content and concentration of harmful substances in the system.

[0003] To achieve the resource-based reuse of circulating water wastewater, a combined process of "coagulation sedimentation + multi-media filtration + ultrafiltration + reverse osmosis" is currently commonly used. Although this process has achieved some success in practical applications, many problems still need to be solved: (1) In the coagulation and sedimentation stage, in order to effectively remove hardness ions in the water, a large amount of lime and sodium carbonate are usually added. The amount of reagents consumed is large, the operating cost is high, and a large amount of calcium-containing sludge will be generated. Treating it as solid waste not only increases the disposal burden, but also wastes calcium resources and fails to achieve resource recycling.

[0004] (2) Ultrafiltration generally uses pressure organic membrane filtration. This type of membrane material has weak anti-fouling ability and is easily clogged by organic matter. It requires frequent backwashing. The concentrated water generated during backwashing also needs further treatment. At the same time, the service life of organic membranes is relatively short, and the stability and maintenance cost of the system face challenges.

[0005] (3) The reverse osmosis system operates at high pressure and consumes a lot of energy. Furthermore, the membrane elements are easily affected by residual hardness ions and organic pollutants in the water, leading to frequent membrane fouling and scaling problems. Regular cleaning with chemical agents is required, which shortens the service life of the membrane components and increases the operation and maintenance costs.

[0006] (4) The water recovery rate of the entire reuse treatment system is limited, usually between 50% and 75%, which is difficult to improve further, thus restricting the efficient use of water resources and affecting the economy and sustainability of the system.

[0007] There are currently no effective solutions to the problems in the relevant technologies. Summary of the Invention

[0008] In view of the problems in related technologies, the present invention proposes a circulating water wastewater reuse and treatment system to overcome the above-mentioned technical problems existing in the existing related technologies.

[0009] Therefore, the specific technical solution adopted by the present invention is as follows: A circulating water wastewater reuse treatment system, comprising: an induced crystallization unit, a ceramic membrane filtration unit, and a nanofiltration membrane unit connected in sequence; The induced crystallization unit is used to perform preliminary treatment of circulating water discharge through an induced crystallization fluidized bed reactor to remove hardness ions from the water; A ceramic membrane filtration unit is used to perform secondary treatment on pre-treated water using a ceramic membrane device to remove residual hardness ions, organic matter, and suspended solids from the water. The nanofiltration membrane unit is used to treat water tertiarily using nanofiltration membranes based on the results of secondary treatment, removing salts and organic matter from the water.

[0010] Furthermore, to remove hardness ions from the water and achieve preliminary treatment, the induced crystallization unit includes: a wastewater conditioning tank for storing circulating wastewater; an induced crystallization fluidized bed reactor for reacting calcium and magnesium ions in the circulating wastewater with added alkaline agents, and gradually depositing crystals on the surface of crystal nuclei in a fluidized state to form crystals, and discharging the crystallization products through a set cycle to remove hardness ions from the water and achieve preliminary treatment; and an intermediate water tank for storing the pre-treated water. The wastewater conditioning tank, the induced crystallization fluidized bed reactor, and the intermediate water tank are connected in sequence by pipelines. The bottom of one side of the induced crystallization fluidized bed reactor is equipped with a NaOH reagent inlet, a Na2CO3 reagent inlet, and a crystal discharge port in sequence.

[0011] Furthermore, to enhance the efficiency of crystal nucleus generation and growth, and improve the induced crystallization effect, the induced crystallization fluidized bed reactor includes: a top reflux inlet for returning pre-treated water to the front end of the induced crystallization fluidized bed reactor and maintaining the internal hydraulic circulation and fluidization state; an alternating electromagnetic field generator for promoting the nucleation reaction between calcium and magnesium ions in the water and the added alkaline agent by applying an alternating electromagnetic field, thereby accelerating the formation of crystal nuclei; a circulation pump for ensuring sufficient contact between the circulating water and wastewater, the agent, and the crystal nuclei through hydraulic circulation, thereby continuously inducing the crystallization reaction; and a water distributor with a swirl head for achieving uniform distribution of the incoming water and promoting the mixing of calcium and magnesium ions in the water with the added alkaline agent through the rotating water flow generated by the swirl head; the alternating electromagnetic field generator is located in the middle of the other side of the induced crystallization fluidized bed reactor, the circulation pump is located at the bottom of the other side of the induced crystallization fluidized bed reactor, and the water distributor with a swirl head is located at the inner bottom of the induced crystallization fluidized bed reactor.

[0012] Furthermore, to promote rapid crystal nucleus generation and improve hardness ion removal efficiency, the seed crystals added inside the induced crystallization fluidized bed reactor are either calcium carbonate or quartz sand, with a particle size of 0.5 mm to 1 mm; the frequency of the alternating electromagnetic field generator is 100 Hz, and the magnetic induction intensity is 0.7 T to 1.2 T; the solution added at the NaOH reagent inlet is NaOH solution, and the reaction pH is adjusted to 9.5 to 11; the solution added at the Na2CO3 reagent inlet is Na2CO3 solution, generating supersaturated calcium carbonate, and the induced crystallization reaction time is 20 min to 30 min.

[0013] Furthermore, to achieve filtration and water purification and improve removal efficiency, the ceramic membrane filtration unit includes: a self-cleaning filter for preliminary filtration of the pre-treated water to remove particulate impurities and suspended solids; a ceramic membrane device for secondary filtration of the pre-filtered water to remove residual hardness ions, organic matter, and suspended solids, thus achieving secondary treatment; and an ultrafiltration permeate tank for storing the secondary-treated water. The self-cleaning filter, ceramic membrane device, and ultrafiltration permeate tank are connected sequentially by pipes. The bottom of the ceramic membrane device has an inlet, and the top of the ceramic membrane device has a cross-flow outlet and a permeate outlet. The inlet is connected to the self-cleaning filter by a pipe, the cross-flow outlet is connected to an intermediate water tank by a pipe, and the permeate outlet is connected to the ultrafiltration permeate tank by a pipe. An acid mixing device is installed on the pipe between the permeate outlet and the ultrafiltration permeate tank, and the acid solution in the acid mixing device is either hydrochloric acid or sulfuric acid.

[0014] Furthermore, in order to remove impurities and residual hardness and improve water treatment efficiency, the self-cleaning filter uses a stainless steel filter screen with a filtration accuracy of 50μm; the membrane module in the ceramic membrane device is an internal pressure tube type ceramic ultrafiltration membrane with a pore size of 0.03μm~0.05μm. The internal pressure tube type ceramic ultrafiltration membrane is a cross-flow filter with a cross-flow velocity of 1.5m / s~2m / s and an operating pressure of 0.15MPa~0.5MPa.

[0015] Furthermore, to achieve deep purification and selective desalination, remove organic matter and hardness ions, and improve the stability of reclaimed water quality, the nanofiltration membrane unit includes: a security filter for security filtration of the secondary-treated water; a pulsed ultrasonic scale inhibitor for emitting pulsed ultrasonic waves according to a preset cycle to interfere with the binding process of scale-forming ions in the water, thereby inhibiting scale formation and achieving tertiary treatment; a nanofiltration unit for selective desalination of the tertiary-treated water and removal of organic matter; and a nanofiltration permeate tank for storing the nanofiltration-treated water. The security filter, pulsed ultrasonic scale inhibitor, nanofiltration unit, and nanofiltration permeate tank are connected sequentially by pipelines. A scale inhibitor mixer is installed on the pipeline between the ultrafiltration permeate tank and the security filter. The security filter contains a filter element with a filtration accuracy of 5μm. The pulsed ultrasonic scale inhibitor generates ultrasonic waves at a frequency of 20kHz and a power of 15W / m according to a preset cycle. 3 Water.

[0016] Furthermore, in order to improve desalination efficiency, enhance antifouling capabilities, and ensure stable system operation, the membrane modules in the nanofiltration unit are arranged in a single-stage two-section continuous or single-stage three-section continuous configuration, and the nanofiltration membranes in the membrane modules are 50mil channel nanofiltration membranes.

[0017] Furthermore, to ensure stable water flow and improve the overall system operating efficiency and water quality assurance capabilities, the intermediate water tank is connected to the self-cleaning filter via pipeline; the ultrafiltration product water tank is connected to the security filter via pipeline.

[0018] Furthermore, in order to ensure stable water supply between units, optimize system operating efficiency, and reduce energy consumption, booster pumps are installed on the pipelines between the wastewater regulating tank and the induced crystallization fluidized bed reactor, the intermediate water tank and the self-cleaning filter, and the ultrafiltration permeate tank and the security filter; a booster pump is installed on the pipeline between the security filter and the pulse ultrasonic scale inhibitor.

[0019] The beneficial effects of this invention are as follows: 1. This invention employs an induced crystallization unit, resulting in a simple system structure, high operating efficiency, improved calcium ion removal rate, reduced alkali consumption, and the generation of high-purity calcium carbonate crystals. This facilitates resource recovery and eliminates the need for dehydration treatment, making it suitable for complex water qualities such as high salt content and the presence of scale inhibitors. Simultaneously, the alternating electromagnetic field enhances the crystallization process, promotes crystal nucleus formation, improves treatment efficiency, and reduces reagent dosage.

[0020] 2. This invention removes suspended solids from wastewater through cross-flow filtration of ceramic membranes, reducing pollutant adhesion, lowering energy consumption, and increasing water recovery rate. By incorporating nanofiltration membranes, it provides higher water production and lower energy consumption. The charge repulsion effect on the membrane surface reduces deposition and extends the cleaning cycle. Combined with a pulsed ultrasonic scale inhibitor, it improves the working efficiency of the nanofiltration membrane and further enhances the overall system performance.

[0021] 3. This invention combines induced crystallization, ceramic membrane and nanofiltration membrane technologies to synergistically treat circulating water discharge, achieving a simplified process, reduced energy consumption and extended backwashing cycle. This not only reduces the amount of chemicals used and sludge generated, but also improves the water recovery rate, thereby removing hardness and realizing calcium resource recovery, thus achieving the goal of water resource reuse and improving overall performance. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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 these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a circulating water wastewater reuse treatment system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the process flow of a circulating water wastewater reuse treatment system according to an embodiment of the present invention.

[0024] In the picture: 1. Wastewater equalization tank; 2. Induced crystallization fluidized bed reactor; 2a. Alternating electromagnetic field generator; 2b. Circulating pump; 2c. Water distributor with swirling cloth head; 3. Intermediate water tank; 4. Self-cleaning filter; 5. Ceramic membrane device; 6. Ultrafiltration permeate tank; 7. Security filter; 8. Pulsed ultrasonic scale inhibitor; 9. Nanofiltration device; 10. Nanofiltration permeate tank; 11. NaOH reagent inlet; 12. Na2CO3 reagent inlet; 13. Acid mixing device; 14. Scale inhibitor mixing device. Detailed Implementation

[0025] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention.

[0026] According to an embodiment of the present invention, a circulating water wastewater reuse treatment system is provided.

[0027] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figure 1 As shown, the circulating water wastewater reuse treatment system according to an embodiment of the present invention includes: an induced crystallization unit I, a ceramic membrane filtration unit II, and a nanofiltration membrane unit III connected in sequence. The induced crystallization unit I is used to perform preliminary treatment of circulating wastewater through the induced crystallization fluidized bed reactor 2 to remove hardness ions from the water.

[0028] In this optional embodiment, the induced crystallization unit I includes: a wastewater conditioning tank 1 for storing circulating wastewater; an induced crystallization fluidized bed reactor 2 for reacting calcium and magnesium ions in the circulating wastewater with added alkaline agents, and gradually depositing crystals on the surface of crystal nuclei in a fluidized state to form crystals, and discharging the crystallization products through a set period to remove hardness ions from the water and achieve preliminary treatment; and an intermediate water tank 3 for storing the pre-treated water; the wastewater conditioning tank 1, the induced crystallization fluidized bed reactor 2, and the intermediate water tank 3 are connected in sequence by pipes; the bottom of the induced crystallization fluidized bed reactor 2 is respectively provided with a NaOH agent inlet 11, a Na2CO3 agent inlet 12, and a crystal discharge port, thereby removing hardness ions from the water and achieving preliminary treatment.

[0029] It should be noted that the top overflow outlet of the induced crystallization fluidized bed reactor 2 is connected to the intermediate water tank 3 via a pipe.

[0030] In this optional embodiment, the induced crystallization fluidized bed reactor 2 includes: a top reflux port for returning pre-treated water to the front end of the induced crystallization fluidized bed reactor and maintaining the internal hydraulic circulation and fluidization state; an alternating electromagnetic field generator 2a for promoting the nucleation reaction between calcium and magnesium ions in the water and the added alkaline agent by applying an alternating electromagnetic field, thereby accelerating the formation of crystal nuclei; a circulation pump 2b for ensuring sufficient contact between the circulating water discharge and the agent and crystal nuclei through hydraulic circulation, thereby continuously inducing the crystallization reaction; and a water distributor 2c with a swirl cloth head for achieving uniform distribution of the incoming water and promoting the mixing of calcium and magnesium ions in the water with the added alkaline agent through the rotating water flow generated by the swirl cloth head; the alternating electromagnetic field generator 2a is located in the middle of the other side of the induced crystallization fluidized bed reactor 2, the circulation pump 2b is located at the bottom of the other side of the induced crystallization fluidized bed reactor 2, and the water distributor 2c with a swirl cloth head is located at the inner bottom of the induced crystallization fluidized bed reactor 2, thereby enhancing the crystal nuclei generation and growth efficiency and improving the induced crystallization effect.

[0031] In this optional embodiment, the seed crystals added inside the induced crystallization fluidized bed reactor 2 are either calcium carbonate or quartz sand, and the particle size of the seed crystals is 0.5 mm to 1 mm; the frequency of the alternating electromagnetic field generator 2a is 100 Hz, and the magnetic induction intensity is 0.7 T to 1.2 T; the solution added to the NaOH reagent inlet 11 is a NaOH solution, and the reaction pH is adjusted to 9.5 to 11; the solution added to the Na2CO3 reagent inlet 12 is a Na2CO3 solution, which generates supersaturated calcium carbonate, and the induced crystallization reaction time is 20 min to 30 min, thereby promoting the rapid generation of crystal nuclei and improving the hardness ion removal efficiency.

[0032] Ceramic membrane filtration unit II is used to perform secondary treatment on the pre-treated water using ceramic membrane device 5, removing residual hardness ions, organic matter and suspended solids from the water.

[0033] In this optional embodiment, the ceramic membrane filtration unit II includes: a self-cleaning filter 4 for preliminary filtration of the pre-treated water to remove particulate impurities and suspended solids; a ceramic membrane device 5 for secondary filtration of the pre-filtered water to remove residual hardness ions, organic matter, and suspended solids, thereby achieving secondary treatment; and an ultrafiltration permeate tank 6 for storing the secondary-treated water. The self-cleaning filter 4, the ceramic membrane device 5, and the ultrafiltration permeate tank 6 are connected sequentially by pipes. The bottom of the ceramic membrane device 5 is provided with an inlet, and the top of the ceramic membrane device 5 is provided with a cross-flow outlet and a permeate outlet. The inlet is connected to the self-cleaning filter 4 by a pipe, the cross-flow outlet is connected to the intermediate water tank 3 by a pipe, and the permeate outlet is connected to the ultrafiltration permeate tank 6 by a pipe. An acid mixing device 13 is provided on the pipe between the permeate outlet and the ultrafiltration permeate tank 6, and the acid solution in the acid mixing device 13 is either hydrochloric acid or sulfuric acid, thereby achieving filtration and water purification and improving removal efficiency.

[0034] In this optional embodiment, the self-cleaning filter 4 uses a stainless steel filter screen with a filtration accuracy of 50μm; the membrane module in the ceramic membrane device 5 is an internal pressure tube type ceramic ultrafiltration membrane with a pore size of 0.03μm~0.05μm. The internal pressure tube type ceramic ultrafiltration membrane is a cross-flow filter with a cross-flow velocity of 1.5m / s~2m / s and an operating pressure of 0.15MPa~0.5MPa, thereby removing impurities and residual hardness and improving the water treatment effect.

[0035] Nanofiltration membrane unit III is used to perform tertiary treatment of water using nanofiltration membranes based on the results of secondary treatment, removing salts and organic matter from the water.

[0036] In this optional embodiment, the nanofiltration membrane unit III includes: a security filter 7 for security filtration of the secondary treated water; a pulsed ultrasonic scale inhibitor 8 for emitting pulsed ultrasonic waves according to a preset cycle to interfere with the binding process of scale-forming ions in the water, thereby inhibiting scale formation and achieving tertiary treatment; a nanofiltration device 9 for selectively desalinating the tertiary treated water and removing organic matter; and a nanofiltration product tank 10 for storing the nanofiltration treated water. The security filter 7, pulsed ultrasonic scale inhibitor 8, nanofiltration device 9, and nanofiltration product tank 10 are connected sequentially by pipelines. A scale inhibitor mixer 14 is installed on the pipeline between the ultrafiltration product tank 6 and the security filter 7. The security filter 7 has a filter element with a filtration accuracy of 5μm, and the pulsed ultrasonic scale inhibitor 8 generates ultrasonic waves with a frequency of 20kHz and a power of 15W / m according to a preset cycle. 3 This process effectively purifies and selectively desalinates the water, removing organic matter and hardness ions, and improving the stability of reclaimed water quality.

[0037] In this optional embodiment, the membrane modules in the nanofiltration device 9 are arranged in a single-stage two-stage continuous or single-stage three-stage continuous manner, and the nanofiltration membranes in the membrane modules are 50mil flow channel nanofiltration membranes, thereby improving desalination efficiency, enhancing antifouling ability, and ensuring stable system operation.

[0038] It should be noted that the permeate from nanofiltration unit 9 enters nanofiltration permeate tank 10 and can be used for makeup water for the production unit. The concentrated water produced by nanofiltration unit 9 is sent to a wastewater treatment plant for further treatment.

[0039] In this optional embodiment, the intermediate water tank 3 is connected to the self-cleaning filter 4 via a pipe; the ultrafiltration water production tank 6 is connected to the security filter 7 via a pipe, thereby ensuring the stability of the water flow and improving the overall system operating efficiency and water quality assurance capability.

[0040] In this optional embodiment, booster pumps are installed on the pipelines between the wastewater regulating tank 1 and the induced crystallization fluidized bed reactor 2, the pipelines between the intermediate water tank 3 and the self-cleaning filter 4, and the pipelines between the ultrafiltration permeate tank 6 and the security filter 7; a booster pump is installed on the pipeline between the security filter 7 and the pulse ultrasonic scale inhibitor 8, thereby ensuring stable water supply between each unit, optimizing system operating efficiency, and reducing energy consumption.

[0041] It should be noted that the following is a method for treating circulating water wastewater in a circulating water wastewater reuse treatment system: The circulating wastewater collected in the wastewater conditioning tank 1 is pumped into the induced crystallization fluidized bed reactor 2 by a lift pump. NaOH solution is added to adjust the wastewater pH to 9-11, and Na2CO3 solution is added to generate supersaturated calcium carbonate. Seed crystals are added once (only once during wastewater treatment, no further replenishment is needed). Induced crystallization occurs in the fluidized bed reactor 2, where calcium and magnesium ions react with alkaline agents and gradually crystallize on crystal nuclei. As the crystal nuclei enlarge, they are periodically discharged, initially removing hardness. The treated wastewater overflows from the induced crystallization fluidized bed reactor 2 into the intermediate water tank 3. The induced crystallization fluidized bed reactor 2 is equipped with an internal circulation device, which includes a return port connected in sequence by pipes and an alternating electromagnetic field. The system consists of a generator 2a, a circulating pump 2b, and a water distributor 2c with a swirling cloth head. The circulating pump uses hydraulic circulation to continuously induce crystallization between the wastewater and the reagents and crystal nuclei in the reactor. An alternating electromagnetic field generator 2a promotes crystal nucleus formation. The alternating electromagnetic field frequency is 100Hz, and the magnetic induction intensity is 0.7T~1.2T. The low-frequency alternating magnetic field also reduces Na2CO3 consumption and reaction time. The crystallization reaction time is 20min~30min. The seed crystals are calcium carbonate or quartz sand with a particle size of 0.5mm~1mm. After the induced crystallization reaction, the particle size increases to 2mm~3mm. The crystals are periodically discharged. The resulting crystallized products have high purity; the calcium carbonate purity can reach over 98%, and it can be further recovered. The hardness (calculated as carbonic acid) of the effluent after induced crystallization treatment is <200mg / L.

[0042] After induced crystallization treatment, the alkaline effluent is pumped from intermediate water tank 3 into the self-cleaning filter 4 of ceramic membrane filtration unit II via a booster pump. The self-cleaning filter 4 removes larger particles to prevent damage to the ceramic membrane. The filtered effluent then enters ceramic membrane device 5 for further filtration, where residual hardness, suspended solids, and organic matter are further removed. The cross-flow effluent (unfiltered wastewater) generated by ultrafiltration is returned to intermediate water tank 3 for further treatment via a cross-flow circulation outlet and pipeline. The ultrafiltration filtrate enters ultrafiltration permeate tank 6 through the permeate outlet. The self-cleaning filter 4 has a filtration accuracy of 50 μm, effectively removing larger particles. To prevent particulate matter in the water from damaging the membrane module of the subsequent ceramic membrane unit 5; the membrane module of the ceramic membrane unit 5 is an internal pressure tubular ceramic ultrafiltration membrane, the membrane material is alumina and zirconium oxide, and the membrane surface pore size is 0.03μm~0.05μm; cross-flow filtration is performed using the ceramic membrane unit 5, the membrane surface flow velocity is 1.5m / s~2m / s, the operating pressure is 0.15MPa~0.5MPa, and the membrane flux is 80LMH~150LMH; the hardness (as carbonic acid) of the effluent after treatment by the ceramic membrane filtration unit II is <60mg / L, and the sludge density index SDI is <3; the ultrafiltration membrane module is periodically cleaned with chemicals.

[0043] Acid is added to the ultrafiltration effluent through an acid mixer 13 connected to the ceramic membrane device 5 and the ultrafiltration permeate tank 6, adjusting the pH of the effluent to 7-8 to improve the quality of the nanofiltration permeate. Then, scale inhibitor is added to the ultrafiltration effluent through a scale inhibitor mixer 14 connected to the ultrafiltration permeate tank 6 and the security filter 7 to prevent membrane fouling. The effluent is then pumped by a booster pump into the security filter 7 for impurity filtration to prevent damage to the nanofiltration membrane. The filtered effluent is then pumped by a booster pump into a pulsed ultrasonic scale inhibitor 8, which periodically emits 20kHz ultrasound waves. Utilizing the cavitation, activation, shearing, and inhibition effects of ultrasound, scale-forming substances such as calcium hardness in the wastewater are dispersed, crushed, and loosened, increasing the nanofiltration permeate rate and extending the cleaning cycle. The pulsed ultrasonic effluent enters the nanofiltration device 9 for salt separation. Most of the hardness, salt, and organic matter in the nanofiltration effluent are removed, significantly reducing the hardness and TDS, meeting the standards for reused water. The concentrated water from the nanofiltration is then sent to a subsequent wastewater treatment unit for further treatment. The acid can be hydrochloric acid or sulfuric acid; the filtration accuracy of the security filter 7 is 5μm; the pulse ultrasonic scale inhibitor 8 periodically generates ultrasonic waves at a frequency of 20kHz and a power of 15W / m. 3 Water; the nanofiltration unit 9 uses a polyamide nanofiltration membrane with a molecular weight cutoff of 150 Da to 300 Da. The membrane module is arranged in a single-stage two-stage continuous or single-stage three-stage continuous configuration. The operating pressure during nanofiltration is 0.5 MPa to 1.5 MPa. The nanofiltration membrane can effectively retain divalent ions (SO42-). 2- Ca 2 + This reduces the hardness of the produced water and can retain some monovalent ions (Cl). - Na + The hardness of the nanofiltration permeate is <10mg / L, and the total dissolved solids (TDS) is <1000mg / L, meeting the water quality standards for reused water.

[0044] The water recovery rate of the wastewater after treatment by the wastewater treatment system of the present invention is >80%; the wastewater treatment system of the present invention is suitable for high recovery rate resource utilization treatment of industrial wastewater with high hardness and medium salinity (such as circulating water discharge from power plants and chemical plants).

[0045] Furthermore, an embodiment of a circulating water wastewater reuse treatment system is as follows: Example 1

[0046] like Figure 2As shown, the system includes an induced crystallization unit I, a ceramic membrane filtration unit II, and a nanofiltration membrane unit III. The induced crystallization unit I includes a wastewater conditioning tank 1, an induced crystallization fluidized bed reactor 2, and an intermediate water tank 3, which are connected in sequence via pipelines. The ceramic membrane filtration unit II includes a self-cleaning filter 4, a ceramic membrane device 5, and an ultrafiltration permeate tank 6, which are connected in sequence via pipelines. The intermediate water tank 3 is connected to the self-cleaning filter 4 via a pipeline. The nanofiltration membrane separation unit includes a security filter 7, a pulsed ultrasonic scale inhibitor 8, a nanofiltration device 9, and a nanofiltration permeate tank 10, which are connected in sequence via pipelines. The ultrafiltration permeate tank 6 is connected to the security filter 7 via a pipeline. The nanofiltration device 9 is equipped with a concentrated water discharge outlet and a recycled water discharge outlet. The recycled water discharge outlet is connected to the nanofiltration permeate tank 10 via a pipeline, and the concentrated water is discharged to the wastewater treatment plant for further treatment.

[0047] The induced crystallization fluidized bed reactor 2 is equipped with an internal circulation device. This device includes a top reflux port, an alternating electromagnetic field generator 2a, a circulation pump 2b, and a water distributor 2c with a swirling cloth head, all connected in sequence by pipes. The bottom of the induced crystallization fluidized bed reactor 2 is equipped with a NaOH reagent inlet 11, a Na2CO3 reagent inlet 12, and a crystal discharge port. The top overflow outlet of the induced crystallization fluidized bed reactor 2 is connected to the intermediate water tank 3 via a pipe. The ceramic membrane device 5 is equipped with a cross-flow circulation outlet and a product water discharge outlet. The cross-flow circulation outlet is connected to the intermediate water tank 3 via a pipe, and the product water discharge outlet is connected to the ultrafiltration product water tank 6 via a pipe. The membrane module in the ceramic membrane device 5 is an internal pressure tubular ceramic ultrafiltration membrane.

[0048] An acid mixing device 13 is installed in the pipeline connecting the ceramic membrane device 5 and the ultrafiltration permeate tank 6, through which acid is added to the wastewater. A scale inhibitor mixing device 14 is installed in the pipeline connecting the ultrafiltration permeate tank 6 and the security filter 7, through which scale inhibitor is added to the water. A pulsed ultrasonic scale inhibitor 8 is installed in the pipeline connecting the security filter 7 and the nanofiltration device 9, which periodically generates 20kHz ultrasonic waves to inhibit scale growth in the wastewater.

[0049] The membrane modules in nanofiltration unit 9 are arranged in either a single-stage two-part continuous type or a single-stage three-part continuous type.

[0050] A booster pump is installed on the pipeline connecting the wastewater regulating tank 1 and the induced crystallization fluidized bed reactor 2, the pipeline connecting the intermediate water tank 3 and the self-cleaning filter 4, and the pipeline connecting the ultrafiltration permeate tank 6 and the security filter 7; a booster pump is installed on the pipeline connecting the pulse ultrasonic scale inhibitor 8 and the nanofiltration device 9.

[0051] The method for treating circulating water wastewater using the circulating water wastewater reuse treatment system of the present invention is as follows: Induced crystallization: The circulating wastewater collected in wastewater conditioning tank 1 is pumped into the induced crystallization fluidized bed reactor 2 by a lift pump. NaOH solution is added to adjust the pH of the wastewater to 9.5-11. Na2CO3 is then added to generate supersaturated calcium carbonate, and seed crystals are added all at once. The wastewater undergoes an induced crystallization reaction in the induced crystallization fluidized bed reactor 2. Calcium and magnesium ions in the water react with the alkaline agent and gradually crystallize on the crystal nuclei. After the crystal nuclei enlarge, they are periodically discharged, and the hardness in the wastewater is initially removed. The treated wastewater overflows from the induced crystallization fluidized bed reactor 2 into the intermediate water tank 3. The induced crystallization fluidized bed reactor 2 is equipped with an internal circulation device, which includes a return port and a cross-flow port connected in sequence by pipes. The system consists of an alternating electromagnetic field generator 2a, a circulating pump 2b, and a water distributor 2c with a swirling cloth head. The circulating pump uses hydraulic circulation to continuously induce crystallization reactions between the wastewater and the reagents and crystal nuclei in the reactor. The alternating electromagnetic field generator 2a promotes crystal nucleus formation. The alternating electromagnetic field frequency is 100Hz, and the magnetic induction intensity is 0.7T~1.2T. The low-frequency alternating magnetic field can also reduce the consumption of Na2CO3 and the reaction time. The crystallization reaction time is 20min~30min. The seed crystals are calcium carbonate or quartz sand with a particle size of 0.5mm~1mm. After the induced crystallization reaction, the particle size increases to 2mm~3mm. The crystals are discharged periodically. The resulting crystallized products have high purity, with calcium carbonate purity reaching over 98%, and can be further recycled.

[0052] Ceramic membrane ultrafiltration: After induced crystallization treatment, the alkaline effluent is pumped from the intermediate water tank 3 into the self-cleaning filter 4 of the ceramic membrane filtration unit II for large particle filtration. The filtered effluent then enters the ceramic membrane device 5 for further filtration, where residual hardness, organic matter, and suspended solids are further removed. The cross-flow effluent (unfiltered wastewater) generated by ultrafiltration is returned to the intermediate water tank 3 through the cross-flow circulation outlet and pipeline for further treatment. The ultrafiltration filtrate enters the ultrafiltration permeate tank 6 through the permeate outlet. The cleaning filter 4 has a filtration accuracy of 50μm, filtering larger particles and preventing them from damaging the membrane module of the subsequent ceramic membrane device 5. The membrane module of the ceramic membrane device 5 is an internal pressure tubular ceramic ultrafiltration membrane, made of alumina and zirconium oxide, with a membrane surface pore size of 0.03μm~0.05μm. When using the ceramic membrane device 5 for micro-crossflow filtration, the operating pressure is 0.15MPa~0.5MPa, and the permeate flux is 80LMH~150LMH. The ultrafiltration membrane module is periodically cleaned with chemicals.

[0053] Nanofiltration: Acid is added to the ultrafiltration effluent through an acid mixer 13 connected to the ceramic membrane device 5 and the ultrafiltration permeate tank 6 to adjust the pH of the effluent to 7-8, thereby improving the quality of the permeate. Then, scale inhibitor is added to the ultrafiltration effluent through a scale inhibitor mixer 14 connected to the ultrafiltration permeate tank 6 and the security filter 7 to prevent membrane fouling. Subsequently, the effluent is pumped by a booster pump into the security filter 7 for security filtration. The filtered effluent then enters a pulsed ultrasonic scale inhibitor 8, which periodically generates ultrasonic waves to inhibit scale formation in the wastewater. The effluent is then pumped by a booster pump into the nanofiltration device 9 for salt separation. Most of the hardness, salt, and organic matter in the nanofiltration effluent are removed, and the hardness and TDS of the effluent are significantly reduced, meeting the water quality standards for reuse. The concentrated water after nanofiltration is sent to a subsequent wastewater treatment plant for further treatment. The acid can be hydrochloric acid or sulfuric acid; the filtration accuracy of the security filter 7 is 5μm; the pulsed ultrasonic generator periodically generates ultrasonic waves at a frequency of 20kHz and a power of 15W / m. 3 Water; the nanofiltration unit 9 uses a polyamide nanofiltration membrane with a molecular weight cutoff of 200 Da to 300 Da. The membrane module is arranged in a single-stage two-stage continuous or single-stage three-stage continuous configuration. The operating pressure during nanofiltration is 0.5 MPa to 1.5 MPa. The nanofiltration membrane can effectively retain divalent ions (SO42-). 2- Ca 2+ This reduces the hardness of the produced water and can retain some monovalent ions (Cl). - Na + ).

[0054] Example 2

[0055] The circulating water wastewater treatment system of the present invention is used to treat the circulating water wastewater of a chemical plant: A chemical plant is discharging 140m³ of circulating water wastewater. 3 / h, hardness <740mg / L, TDS <1300mg / L, chloride ion <130mg / L, sulfate ion <180mg / L, COD <40mg / L.

[0056] The processing flow is as follows: The circulating water discharge wastewater enters the wastewater equalization tank 1, and is pumped into the induced crystallization fluidized bed reactor 2 by the booster pump. 30wt% sodium hydroxide aqueous solution and 10wt% sodium carbonate aqueous solution are added to the lower part of the induced crystallization fluidized bed reactor 2 to adjust the pH to 10. Quartz sand seed crystals are initially added to the induced crystallization fluidized bed reactor 2. After the crystallization reaction for 20 minutes, the hardness of the effluent is <140mg / L, and the crystallization product is recovered and reused.

[0057] The permeate from the induced crystallization fluidized bed reactor 2 enters the intermediate water tank 3, and is then transported by a booster pump. It passes sequentially through a self-cleaning filter 4 (filtration accuracy of 50μm) and a ceramic membrane device 5. The membrane pore size of the ceramic membrane device 5 is 0.03μm. The operating pressure during filtration is 0.25MPa, the membrane flux is 100L / (m²·h), the cross-flow filtration membrane surface velocity is 1.5m / s, the hardness of the filtered water is <50mg / L, the SDI of the water is <2.5, and the water enters the ultrafiltration permeate tank 6.

[0058] Ultrafiltration permeate is pumped from ultrafiltration permeate tank 6 into security filter 7 (filtration accuracy of 5μm) for security filtration, and then pumped by booster pump to pulse ultrasonic scale inhibitor 8. After scale inhibition treatment by 20kHz ultrasonic waves, it enters nanofiltration unit 9. The nanofiltration membrane of nanofiltration unit 9 is a polyamide nanofiltration membrane with a molecular weight cutoff of 150Da~300Da. The membrane module arrangement of nanofiltration unit 9 is a single-stage three-stage continuous type. The operating pressure during nanofiltration is 0.7MPa. The hardness of nanofiltration permeate is <5mg / L and TDS is <250mg / L. The nanofiltration permeate enters permeate tank 10 for reuse, and the nanofiltration concentrate is sent to the sewage treatment plant for further treatment.

[0059] The entire system has a water recovery rate of 85% and recovers 550 tons of industrial-grade calcium carbonate per year.

[0060] Compared to traditional chemical precipitation methods, the induced crystallization unit I of this invention's wastewater treatment system has a simpler process and equipment, achieving a calcium ion removal rate of over 90% (compared to 70%-80% for precipitation methods). It is particularly suitable for complex water quality containing scale inhibitors and high salinity, reducing alkali consumption by over 20%. A single addition of seed crystals results in more crystal nuclei after crystallization, producing high-purity crystal products, with calcium carbonate purity exceeding 98%, which can be further recovered. Furthermore, its moisture content is less than 10%, eliminating the need for dewatering facilities. Traditional chemical precipitation methods require large amounts of alkali, producing sludge containing various impurities, requiring solid waste treatment only, and with a moisture content exceeding 95%, necessitating further dewatering. The induced crystallization internal circulation system utilizes an alternating electromagnetic field generator to enhance crystal nucleus formation, reducing reaction time and the amount of sodium carbonate and other chemicals required.

[0061] Compared to external pressure organic membranes, the ceramic membrane used in this invention employs cross-flow filtration to treat higher concentrations of suspended solids. It can reduce residual hardness and suspended solids after induced crystallization hardening to even lower levels, resulting in a lower SDI value in the effluent and reduced nanofiltration membrane fouling. The ceramic membrane exhibits stronger resistance to acids, alkalis, and high salts, as well as higher temperature resistance, and is easier to clean and restore flux after fouling. It can withstand operating pressures greater than 0.6 MPa and is not easily broken or deformed by particulate impact or high-pressure backwashing, with a service life of over 10 years. (The last sentence appears to be incomplete and possibly refers to a different invention: "Due to leakage in the heat exchanger of the device, wastewater...") When oil is present, the ceramic membrane has a smooth surface and better oleophobic properties, which can reduce the adhesion of pollutants. It can also operate under alkaline conditions for a long time, making it more suitable for treating circulating water and sewage with high hardness and high suspended solids. The external pressure organic ultrafiltration membrane uses an organic PVDF membrane, which has much lower corrosion resistance, temperature resistance, and pressure resistance than the ceramic membrane. It needs to be replaced after about 3 years of use. When the suspended solids content of the influent is higher than 100mg / L, a sand filter pretreatment is required before ultrafiltration. This results in a longer process, a larger backwash water volume, increased energy consumption, and also affects the water recovery rate of the entire system.

[0062] This invention utilizes nanofiltration membranes for wastewater treatment. Compared to reverse osmosis, nanofiltration operates at lower pressures, typically 0.5 MPa to 1.0 MPa, while reverse osmosis operates at 1.0 MPa to 5.0 MPa and consumes more energy. The nanofiltration membrane carries a surface charge, which reduces the deposition of organic matter and colloids through charge repulsion. Its chemical cleaning cycle is longer than that of reverse osmosis membranes. Nanofiltration membranes primarily retain divalent and high-valence ions, but also have some retention capacity for monovalent ions. Its permeate flow rate is higher than that of reverse osmosis membranes, and it avoids excessive water softening. For certain circulating wastewater with high chloride ion content, highly negatively charged nanofiltration membranes (such as NF90) or reverse osmosis membranes can be selected to remove chloride ions. - The rejection rate is increased to 60%~70%, still meeting the water quality requirements for reused water; a pulsed ultrasonic scale inhibitor is installed in front of the nanofiltration membrane, which uses the cavitation effect, activation effect, shearing effect and inhibition effect of ultrasound to disperse, crush and loosen scale substances such as calcium in the wastewater, thereby improving the nanofiltration water production rate and extending the membrane cleaning cycle.

[0063] This invention treats circulating wastewater by inducing crystallization in conjunction with ceramic and nanofiltration membranes. The process is shorter, with lower energy consumption, longer backwashing cycles, and less operation and maintenance. The shorter process achieves the triple goals of water resource reuse, efficient hardness removal, and calcium resource recovery from high-hardness circulating wastewater. Compared with traditional flocculation and sedimentation hardness removal processes, it reduces reagent consumption by more than 20%, sludge volume by 60%, and the system water recovery rate can stably reach more than 80%, saving 20% ​​of energy.

[0064] In summary, by employing the above-mentioned technical solution of this invention, the system structure is simple and highly efficient through the use of induced crystallization unit I. This improves the calcium ion removal rate, reduces alkali consumption, and generates high-purity calcium carbonate crystals, facilitating resource recovery and eliminating the need for dehydration treatment. It is also suitable for complex water qualities, including high-salt water and water containing scale inhibitors. Simultaneously, the alternating electromagnetic field enhances the crystallization process, promoting crystal nucleus formation, improving treatment efficiency, and reducing reagent dosage. Cross-flow filtration using ceramic membranes removes suspended solids from wastewater, reduces pollutant adhesion, lowers energy consumption, and increases water recovery rate. The nanofiltration membrane provides higher water production and lower energy consumption. The charge repulsion effect on the membrane surface reduces deposition and extends the cleaning cycle. Combined with the pulsed ultrasonic scale inhibitor 8, the working efficiency of the nanofiltration membrane is improved, further enhancing the overall system performance. By combining induced crystallization, ceramic membrane, and nanofiltration membrane technologies to synergistically treat circulating water discharge, a simplified process, reduced energy consumption, and extended backwashing cycle operation mode has been achieved. This not only reduces the amount of chemicals used and sludge generated, but also improves the water recovery rate, thereby removing hardness and realizing calcium resource recovery, thus achieving the goal of water resource reuse and improving overall performance.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A circulating water wastewater reuse and treatment system, characterized in that, The system includes: an induced crystallization unit, a ceramic membrane filtration unit, and a nanofiltration membrane unit connected in sequence; The induced crystallization unit is used to perform preliminary treatment of circulating water wastewater through an induced crystallization fluidized bed reactor to remove hardness ions from the water; The ceramic membrane filtration unit is used to perform secondary treatment on the pre-treated water using a ceramic membrane device to remove residual hardness ions, organic matter and suspended solids from the water. The nanofiltration membrane unit is used to perform a third treatment on water using a nanofiltration membrane based on the results of the second treatment, thereby removing salt and organic matter from the water.

2. The circulating water wastewater reuse treatment system according to claim 1, characterized in that, The induced crystallization unit includes: Wastewater regulating tank, used to store circulating water and discharged wastewater; The induced crystallization fluidized bed reactor is used to react calcium and magnesium ions in the circulating water discharge with the added alkaline agent, and gradually deposit crystals on the surface of the crystallization nuclei in a fluidized state to form crystals. The crystallization products are discharged by setting a cycle to remove hardness ions from the water and achieve preliminary treatment. The intermediate water tank is used to store the water after preliminary treatment; The wastewater regulating tank, the induced crystallization fluidized bed reactor, and the intermediate water tank are connected in sequence by pipelines; The bottom of one side of the induced crystallization fluidized bed reactor is provided with a NaOH reagent inlet, a Na2CO3 reagent inlet, and a crystal discharge port.

3. The circulating water wastewater reuse treatment system according to claim 2, characterized in that, The induced crystallization fluidized bed reactor includes: The top reflux port is used to return the pre-treated water to the front end of the induced crystallization fluidized bed reactor and maintain the internal hydraulic circulation and fluidization state. An alternating electromagnetic field generator is used to promote the nucleation reaction between calcium and magnesium ions in water and added alkaline agents by applying an alternating electromagnetic field, thereby accelerating the formation of crystal nuclei. A circulating pump is used to ensure that the circulating water and wastewater come into full contact with the reagents and crystal nuclei through hydraulic circulation, thereby continuously inducing the crystallization reaction. A water distributor with a swirl head is used to achieve uniform distribution of incoming water and promote the mixing of calcium and magnesium ions in the water with the added alkaline agents through the rotating water flow generated by the swirl head. The alternating electromagnetic field generator is located in the middle of the other side of the induced crystallization fluidized bed reactor, the circulating pump is located at the bottom of the other side of the induced crystallization fluidized bed reactor, and the water distributor with swirling cloth head is located at the inner bottom of the induced crystallization fluidized bed reactor.

4. The circulating water wastewater reuse treatment system according to claim 3, characterized in that, The seed crystals added inside the induced crystallization fluidized bed reactor are either calcium carbonate or quartz sand, and the particle size of the seed crystals is 0.5 mm to 1 mm. The alternating electromagnetic field generator has a frequency of 100Hz and a magnetic induction intensity of 0.7T~1.2T; The solution added to the NaOH reagent inlet is a NaOH solution, and the reaction pH is adjusted to 9.5~11; The solution added to the Na2CO3 reagent inlet is a Na2CO3 solution, which generates supersaturated calcium carbonate, and the induced crystallization reaction time is 20 min to 30 min.

5. A circulating water wastewater reuse treatment system according to claim 2, characterized in that, The ceramic membrane filtration unit includes: Self-cleaning filters are used to pre-filter water after initial treatment, removing particulate impurities and suspended solids; A ceramic membrane device is used to perform secondary filtration on water after primary filtration to remove residual hardness ions, organic matter and suspended solids in the water, so as to achieve secondary treatment. Ultrafiltration permeate tank is used to store water that has undergone secondary treatment; The self-cleaning filter, the ceramic membrane device, and the ultrafiltration permeate tank are connected in sequence via pipelines. The ceramic membrane device has an inlet at the bottom and a cross-flow outlet and a product water outlet at the top. The inlet is connected to the self-cleaning filter via a pipe, the cross-flow outlet is connected to the intermediate water tank via a pipe, and the product water outlet is connected to the ultrafiltration product water tank via a pipe. An acid mixing device is installed on the pipeline between the product water outlet and the ultrafiltration product water tank, and the acid solution in the acid mixing device is either hydrochloric acid or sulfuric acid.

6. The circulating water wastewater reuse treatment system according to claim 5, characterized in that, The self-cleaning filter uses a stainless steel filter screen, and the filtration accuracy of the stainless steel filter screen is 50μm. The membrane module in the ceramic membrane device is an internal pressure tubular ceramic ultrafiltration membrane, and the pore size of the internal pressure tubular ceramic ultrafiltration membrane is 0.03μm~0.05μm. The internal pressure tubular ceramic ultrafiltration membrane is a cross-flow filtration membrane with a cross-flow velocity of 1.5m / s~2m / s and an operating pressure of 0.15MPa~0.5MPa.

7. A circulating water wastewater reuse treatment system according to claim 6, characterized in that, The nanofiltration membrane unit includes: Security filters are used for security filtration of water after secondary treatment. The pulsed ultrasonic scale inhibitor is used to emit pulsed ultrasonic waves according to a preset cycle to interfere with the binding process of scale-forming ions in water, thereby inhibiting scale formation in wastewater and achieving three-stage treatment. Nanofiltration devices are used to selectively desalinate and remove organic matter from water that has undergone tertiary treatment. Nanofiltration permeate tank, used to store water treated by nanofiltration; The security filter, the pulsed ultrasonic scale inhibitor, the nanofiltration device, and the nanofiltration permeate tank are connected in sequence via pipelines; A scale inhibitor mixer is installed on the pipeline between the ultrafiltration permeate tank and the security filter; The security filter is internally equipped with a filter element, and the filter element has a filtration accuracy of 5μm. The pulse ultrasonic scale inhibitor generates ultrasonic waves with a frequency of 20kHz and a power of 15W / m according to a preset cycle. 3 Water.

8. The circulating water wastewater reuse treatment system according to claim 7, characterized in that, The nanofiltration device is arranged in a single-stage two-section continuous or single-stage three-section continuous configuration, and the nanofiltration membrane in the membrane module is a 50mil flow channel nanofiltration membrane.

9. A circulating water wastewater reuse treatment system according to claim 8, characterized in that, The intermediate water tank is connected to the self-cleaning filter via a pipe; The ultrafiltration permeate tank is connected to the security filter via a pipeline.

10. A circulating water wastewater reuse treatment system according to claim 9, characterized in that, A booster pump is installed on the pipeline between the wastewater regulating tank and the induced crystallization fluidized bed reactor, the pipeline between the intermediate water tank and the self-cleaning filter, and the pipeline between the ultrafiltration permeate tank and the security filter; A booster pump is installed on the pipeline between the security filter and the pulsed ultrasonic scale inhibitor.

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