Desulfurization wastewater low-cost zero-discharge integrated system

Abstract

The invention discloses a desulfurization wastewater low-cost zero-discharge integrated system which comprises a raw water tank, a water outlet of the raw water tank is connected with an acidification reaction tower through a raw water pump, the acidification reaction tower is connected with a dosing mechanism, and an overflow port of the acidification reaction tower is connected with a cyclone separator. A slag outlet in the bottom of the cyclone separator is connected with a carbonate crystallization tank through a sludge discharge pump; by organically combining an acidification carbonate removal technology with RO concentration, flue evaporation and other technologies, the softening process of a traditional dual-alkali method is shortened by 50%, the sludge yield is reduced by 85%, rapid crystallization and separation of carbonate are achieved, the hardness removal rate is larger than 95%, a ceramic membrane and a DTRO membrane operate in series, high-salt and high-hardness water quality is tolerated, the service life of the RO membrane is greatly prolonged, and the service life of the RO membrane is prolonged. And the PX pressure exchanger and the flue gas waste heat are used, so that the energy consumption of the system is effectively reduced, and the problems of high cost, high scaling and high energy consumption of high-salt desulfurization wastewater treatment are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and specifically to an integrated system for low-cost zero discharge of desulfurization wastewater, which is applicable to complex water quality conditions with high salt content (30,000 - 50,000 mg / L) and high hardness (10,000 - 25,000 mg / L). Background Art

[0002] Common pollutants in thermal power plant desulfurization wastewater include relatively high concentrations of sulfate, chloride, fluoride, heavy metals, etc. Among them, sulfate is the main component, and its concentration range is generally between 5 - 25 g / L. In addition to these main components, desulfurization wastewater also contains some organic pollutants such as ferric sulfate, Sudan red, and thiocyanate. This makes it difficult to directly discharge desulfurization wastewater into the environment and requires reasonable treatment.

[0003] Currently, commonly used desulfurization wastewater treatment technologies include precipitation method, ion exchange method, membrane separation method, etc. The precipitation method uses chemical reactions to convert pollutants in the wastewater into solid precipitates. Appropriate calcium ions or aluminum ions are added to the wastewater to form insoluble precipitates with sulfate, heavy metals, etc. in the wastewater, and then the pollutants are removed by precipitation. The ion exchange method uses ion exchange resins to adsorb and exchange ions in the wastewater to achieve the purpose of removing pollutants. The membrane separation method uses membranes with different pore sizes to filter and separate the wastewater to achieve the effect of removing pollutants.

[0004] However, the treatment cost per ton of water for the traditional double-alkali softening process is 30 - 40 yuan / m³, the overall operating cost is 60 - 70 yuan / m³, the sludge production is 25 - 35 kg / m³, and the scaling of calcium sulfate and carbonate during membrane concentration and evaporation crystallization leads to a more than 50% decrease in equipment efficiency and a shortened cleaning cycle. Therefore, there is an urgent need for a desulfurization wastewater treatment technology that combines high-efficiency hardness removal, scale prevention, and low energy consumption. For this reason, we propose an integrated system for low-cost zero discharge of desulfurization wastewater. Summary of the Invention

[0005] The purpose of the present invention is to provide an integrated system for low-cost zero discharge of desulfurization wastewater to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: An integrated system for low-cost zero discharge of desulfurized wastewater, comprising a raw water tank. The water outlet of the raw water tank is connected to an acidification reaction tower through a raw water pump. A chemical dosing mechanism is connected to the acidification reaction tower. The overflow port of the acidification reaction tower is connected to a hydrocyclone separator. The bottom slag outlet of the hydrocyclone separator is connected to a carbonate crystallization tank through a sludge discharge pump. The sludge outlet of the carbonate crystallization tank is connected to a sludge dewatering machine. The water outlet of the hydrocyclone separator is connected to a buffer tank. The water outlet of the buffer tank is connected to a ceramic membrane unit through a first booster pump. The water production port of the ceramic membrane unit is connected to a DTRO membrane stack through a high-pressure pump. The water production port of the DTRO membrane stack is connected to a reused water tank. The concentrated water port of the DTRO membrane stack is connected to a concentrated water tank. The water outlet of the concentrated water tank is connected to a two-fluid atomizer through a diaphragm pump and a preheating heat exchanger. The air inlet of the two-fluid atomizer is connected to a compressed air source. The discharge port of the two-fluid atomizer is connected to a crystal slurry collection hopper through a Z-shaped flue and a cyclone dust collector. The discharge port of the crystal slurry collection hopper is connected to a fluidized bed dryer through a pneumatic pump. The discharge port of the fluidized bed dryer is connected to a finished product bin through a cyclone separator. The air outlets of the cyclone dust collector and the cyclone separator are both connected to a tail gas scrubbing tower through a induced draft fan. The wastewater output port of the tail gas scrubbing tower is connected to the raw water tank through a lift pump. The liquid inlet of the high-pressure pump is also connected to a scale inhibitor storage tank through a screw pump, and scale inhibitor is stored in the scale inhibitor storage tank.

[0007] As a further solution of the present invention: The scale inhibitor comprises the following components in weight percentage: 20-30% of hydroxyethylidene diphosphonic acid, 15-25% of polyaspartic acid, 10-15% of nanocellulose, 5-10% of ferrous sulfate, and the balance is deionized water.

[0008] As a further solution of the present invention: The chemical dosing mechanism comprises an acid liquid storage tank. The liquid outlet end of the acid liquid storage tank is connected to the acidification reaction tower through a first metering pump. A PH transmitter is installed at the overflow port of the acidification reaction tower.

[0009] As a further solution of the present invention: A first pneumatic butterfly valve is installed at the water outlet of the raw water pump. A sludge concentration sensor and a pneumatic knife gate valve are installed on the slag discharge pipe of the hydrocyclone separator. The filtrate output port of the sludge dewatering machine is connected to the raw water tank through a pipeline and an electric control ball valve.

[0010] As a further solution of the present invention: A multi-media filter is installed between the water outlet of the first booster pump and the water inlet of the ceramic membrane unit. The concentrated water port of the ceramic membrane unit is communicated with the liquid inlet of the hydrocyclone separator through a pipeline.

[0011] As a further solution of the present invention: The water production port of the ceramic membrane unit is communicated with the liquid inlet of the high-pressure pump through a PX pressure exchanger. The water production port of the DTRO membrane stack is communicated with the liquid inlet of the concentrated water tank through a PX pressure exchanger.

[0012] As a further solution of the present invention: an SDI sensor and a pneumatic regulating valve are installed between the water outlet of the ceramic membrane unit and the low-pressure side water inlet of the PX pressure exchanger. The low-pressure side water outlet of the PX pressure exchanger is communicated with the water inlet of the high-pressure pump. The water outlet of the DTRO membrane stack is communicated with the high-pressure side water inlet of the PX pressure exchanger. The high-pressure side water outlet of the PX pressure exchanger is communicated with the water inlet of the concentrated water tank, and a pressure relief valve is installed at the high-pressure side water outlet of the PX pressure exchanger.

[0013] As a further solution of the present invention: a flow meter is installed at the discharge port of the scale inhibitor storage tank.

[0014] As a further solution of the present invention: a laser particle size analyzer is installed at the discharge port of the crystal slurry collecting hopper.

[0015] As a further solution of the present invention: a conductivity monitoring sensor is installed at the water outlet of the DTRO membrane stack. The liquid outlet of the reclaimed water tank is connected to the backwash water tank through a lift pump. Backwash pipelines are installed on the hydrocyclone separator, ceramic membrane unit, DTRO membrane stack, PX pressure exchanger and sludge dewatering machine, and the water outlet end of the backwash water tank is communicated with each backwash pipeline through a plurality of water delivery pipes. Backwash pumps and pulse valves are installed on each water delivery pipe.

[0016] Compared with the prior art, the beneficial effects of the present invention are: By organically combining the acidification de-carbonate technology with technologies such as RO concentration and flue gas evaporation, the present invention shortens the traditional dual-alkali method softening process by 50% and reduces the sludge production by 85%, realizes the rapid crystallization separation of carbonate (CaCO3), and the hardness removal rate > 95%. The ceramic membrane and the DTRO membrane operate in series, are resistant to high-salt and high-hardness water quality, greatly extend the service life of the RO membrane, improve the system recovery rate, and effectively reduce the system energy consumption through the use of the PX pressure exchanger and flue gas waste heat, solving the problems of "high cost, high scaling, and high energy consumption" in the treatment of high-salt desulfurization wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural block diagram of an integrated system for low-cost zero-emission of desulfurization wastewater.

[0018] Among them, the raw water tank 1, the raw water pump 2, the first pneumatic butterfly valve 3, the acidification reaction tower 4, the acid liquid storage tank 5, the first metering pump 6, the PH transmitter 7, the hydrocyclone 8, the buffer water tank 9, the first booster pump 10, the multi-media filter 11, the ceramic membrane unit 12, the SDI sensor 13, the pneumatic control valve 14, the high-pressure pump 15, the DTRO membrane stack 16, the PX pressure exchanger 17, the scale inhibitor storage tank 18, the flowmeter 19, the screw pump 20, the pressure relief valve 21, the concentrated water tank 22, the diaphragm pump 23, the preheating heat exchanger 24, the two-fluid atomizer 25, the compressed air source 26, the Z-shaped flue 27, the cyclone dust collector 28, the crystal slurry collection hopper 29, the laser particle size analyzer 30, the pneumatic pump 31, the fluidized bed dryer 32, the cyclone separator 33, the finished product bin 34, the tail gas scrubbing tower 35, the sludge concentration sensor 36, the pneumatic knife gate valve 37, the sludge discharge pump 38, the carbonate crystallization tank 39, the sludge dewatering machine 40, the electric control ball valve 41, the conductivity monitoring sensor 42, the recycled water tank 43, the backwash water tank 44. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] Please refer to Figure 1, in the embodiment of the present invention, an integrated system for low-cost zero discharge of desulfurized wastewater includes a raw water tank 1. The water outlet of the raw water tank 1 is connected to an acidification reaction tower 4 through a raw water pump 2. A dosing mechanism is connected to the acidification reaction tower 4. The overflow port of the acidification reaction tower 4 is connected to a hydrocyclone separator 8. The bottom slag outlet of the hydrocyclone separator 8 is connected to a carbonate crystallization tank 39 through a sludge discharge pump 38. The sludge outlet of the carbonate crystallization tank 39 is connected to a sludge dewatering machine 40. The water outlet of the hydrocyclone separator 8 is connected to a buffer tank 9. The water outlet of the buffer tank 9 is connected to a ceramic membrane unit 12 through a first booster pump 10. The water production port of the ceramic membrane unit 12 is connected to a DTRO membrane stack 16 through a high-pressure pump 15. The water production port of the DTRO membrane stack 16 is connected to a reused water tank 43. The concentrated water port of the DTRO membrane stack 16 is connected to a concentrated water tank 22. The water outlet of the concentrated water tank 22 is connected to a two-fluid atomizer 25 through a diaphragm pump 23 and a preheating heat exchanger 24. The air inlet of the two-fluid atomizer 25 is connected to a compressed air source 26. The discharge port of the two-fluid atomizer 25 is connected to a crystal slurry collection hopper 29 through a Z-shaped flue 27 and a cyclone dust collector 28. Moreover, the preheating heat exchanger 24, the two-fluid atomizer 25, and the Z-shaped flue 27 are all heated by the high-temperature flue gas of the thermal power plant boiler. The discharge port of the crystal slurry collection hopper 29 is connected to a fluidized bed dryer 32 through a pneumatic pump 31. The discharge port of the fluidized bed dryer 32 is connected to a finished product bin 34 through a cyclone separator 33. The air outlets of the cyclone dust collector 28 and the cyclone separator 33 are both connected to a tail gas scrubbing tower 35 through an induced draft fan. The wastewater output port of the tail gas scrubbing tower 35 is connected to the raw water tank 1 through a lift pump. The liquid inlet of the high-pressure pump 15 is also connected to a scale inhibitor storage tank 18 through a screw pump 20, and the scale inhibitor storage tank 18 stores scale inhibitor.

[0021] By adopting the above solution, when in use, the raw water pump 2 pumps the desulfurized wastewater in the raw water tank 1 into the acidification reaction tower 2, and the dosing mechanism adds acid solution into the acidification reaction tower 4 to adjust the pH value of the desulfurized wastewater from alkaline (9 - 11) to weakly acidic (4.5 - 5.5), dissolve carbonates (CaCO3, MgCO3), and prevent fouling of the subsequent membrane system. Then, the hydrocyclone 8 uses centrifugal force to separate the carbonate precipitates generated after acidification to remove more than 80% of the suspended solids and reduce the load on the membrane system. The underflow sludge of the hydrocyclone 8 (solid content 15 - 30%) is transported to the crystallization tank for further treatment. The carbonate crystallization tank 39 promotes the growth of micron-sized carbonate particles into millimeter-sized crystals to achieve sludge reduction and crystal phase stabilization. The remaining sludge is sent into the sludge dehydrator 40 by the sludge discharge pump 38 for dehydration. The wastewater separated by the hydrocyclone 8 enters the buffer water tank 9 and is pumped into the ceramic membrane unit 12 by the first booster pump 10 to finely filter the wastewater, intercept the remaining suspended solids (SS < 10mg / L) and colloidal substances, thereby reducing the silt density index (SDI < 3) and protecting the high-pressure reverse osmosis membrane from particle contamination. The high-pressure pump pumps the clear water produced by the ceramic membrane unit 12 into the DTRO membrane stack 16 to concentrate the wastewater under a high pressure of 8 - 12MPa, increasing the TDS from 30000mg / L to more than 180000mg / L. The purified water discharged from the water outlet of the DTRO membrane stack 16 enters the reuse water tank 43 for standby, while the concentrated wastewater enters the concentrated water tank 22. The diaphragm pump 23 pumps the concentrated wastewater in the concentrated water tank 22 into the preheating heat exchanger 24 for preheating and then introduces it into the two-fluid atomizer 25. The two-fluid atomizer 25 atomizes the high-salt concentrated water (TDS > 180000mg / L) into 50 - 80μm droplets, uses the waste heat of the flue gas to evaporate water, and the wastewater evaporation rate > 95%. The crystallized salts are collected in the form of crystal slurry. The Z-shaped flue 27 can extend the contact time between the flue gas and the atomized droplets (contact time > 5 seconds), promote water evaporation and salt crystallization. The cyclone dust collector 28 can separate the salt crystal particles (particle size > 10μm) at the flue outlet, with a dust removal efficiency > 85% and an emission dust concentration < 30mg / m³. The collected salt crystals (water content < 35%) are transported to the fluidized bed dryer 32 for drying. The fluidized bed dryer 32 realizes gradient drying with three-stage temperature control (80℃ / 120℃ / 60℃) to dry the wet salt crystals (water content 35%) into anhydrous finished salts (water content < 5%) with a salt purity > 98%. In addition, the screw pump 20 can regularly pump the scale inhibitor in the scale inhibitor storage tank 18 into the DTRO membrane stack 16 to inhibit the scaling of calcium sulfate on the surface of the RO membrane, thereby extending the cleaning cycle of the DTRO membrane stack 16. After verification, the treatment of desulfurized wastewater by this system achieves the goals of reducing the operating cost by 40%, reducing sludge by 85%, and having a system recovery rate > 98% compared with traditional technologies.

[0022] In one embodiment of the present invention, the scale inhibitor comprises the following components in weight percentages: 20-30% of hydroxyethane diphosphonic acid, 15-25% of polyaspartic acid, 10-15% of nanocellulose, 5-10% of ferrous sulfate, and the balance is deionized water. Further, the preparation method of the scale inhibitor is as follows: Step 1: Pretreatment of raw materials: Nanocellulose (CNF): Prepared by acid hydrolysis method (concentration 5%, reaction at 80 °C for 2 h), centrifuged and purified, and then dried to a moisture content of <5%.

[0023] Ferrous sulfate (FeSO4·7H2O): Pre-dehydrated at 120 °C for 12 h and pulverized to a particle size of <100 μm.

[0024] Step 2: Preparation of composite solution: Dissolve hydroxyethane diphosphonic acid (HEODP) and polyaspartic acid (PASP) in deionized water, ultrasonically disperse for 30 min (power 200 W, frequency 40 kHz), then add nanocellulose (CNF), and stir at high speed (8000 rpm, 15 min) to form a homogeneous solution. Then slowly add ferrous sulfate (FeSO4·7H2O) and continuously stir magnetically for 2 h to ensure complete dissolution of Fe³⁺.

[0025] Step 3: Post-treatment and shaping: Ultrafiltration concentration (cut-off molecular weight 10 kDa) to obtain a concentrated solution (solid content 30-40%), and then freeze-dry (-50 °C, vacuum degree 5 Pa) or spray-dry (inlet air temperature 180 °C, outlet air temperature 80 °C) to prepare a powdery scale inhibitor.

[0026] By adding hydroxyethane diphosphonic acid (HEODP), the above scale inhibitor can inhibit the polymerization of Ca²⁺ and SO4²⁻ ions; by adding polyaspartic acid (PASP), it can coordinate the hydroxyl group with calcium ions to chelate hardness ions; by adding nanocellulose (CNF), it can enhance the dispersibility of the agent and delay sedimentation; by adding ferrous sulfate (FeSO4·7H2O), it can utilize Fe³⁺ to dope the crystal lattice, thereby distorting calcium sulfate crystals. Moreover, the biodegradation rate of this scale inhibitor >90% (tested by 28-day MBR), the COD emission <100 mg / L, it is a phosphorus-free formulation, avoiding the risk of eutrophication, and the scale prevention rate remains >85% during continuous operation at 80 °C for 200 h.

[0027] Specifically combined with Figure 1, in an embodiment of the present invention, the chemical dosing mechanism includes an acid liquid storage tank 5. The liquid outlet end of the acid liquid storage tank 5 is connected to the acidification reaction tower 4 through a first metering pump 6. A pH transmitter (i.e., an existing water quality monitoring probe for measuring acidity / alkalinity / pH value) 7 is installed at the overflow port of the acidification reaction tower 4. By setting the pH transmitter 7, the pH value of the effluent from the acidification reaction tower 4 can be monitored and fed back to the first metering pump 6 in real time, so as to add an appropriate amount of acid liquid into the acidification reaction tower 4 to maintain the pH value of the liquid in the acidification reaction tower 4 at 4.5 - 5.5.

[0028] Specifically combined with Figure 1 , in an embodiment of the present invention, a first pneumatic butterfly valve 3 is installed at the water outlet of the raw water pump 2. A sludge concentration sensor 36 and a pneumatic knife gate valve 37 are installed on the slag discharge pipe of the hydrocyclone separator 8. By setting the sludge concentration sensor 36, the bottom flow sludge concentration of the hydrocyclone separator 8 can be monitored, and the pneumatic knife gate valve 37 is opened to discharge the sludge after the concentration reaches the standard. The filtrate output port of the sludge dewatering machine 40 is connected to the raw water tank 1 through a pipeline and an electric control ball valve 41.

[0029] Specifically combined with Figure 1 , in an embodiment of the present invention, a multi-media filter 11 is installed between the water outlet of the first booster pump 10 and the water inlet of the ceramic membrane unit 12 to pre-filter the sewage entering the ceramic membrane unit 12, so as to remove large particle impurities in the sewage. The concentrated water outlet of the ceramic membrane unit 12 is communicated with the liquid inlet of the hydrocyclone separator 8 through a pipeline to re-treat the concentrated water produced by the ceramic membrane unit 12.

[0030] Specifically combined with Figure 1 , in an embodiment of the present invention, the water production port of the ceramic membrane unit 12 is communicated with the water inlet of the high-pressure pump 15 through a PX pressure exchanger 17. The water production port of the DTRO membrane stack 16 is communicated with the water inlet of the concentrated water tank 22 through a PX pressure exchanger 17.

[0031] Further, an SDI sensor (i.e., an existing Silt Density Index sensor) 13 and a pneumatic control valve 14 are installed between the water production outlet of the ceramic membrane unit 12 and the low-pressure side water inlet of the PX pressure exchanger 17. The low-pressure side water outlet of the PX pressure exchanger (i.e., a commercially available PX series pressure exchanger of American ERI Company) 17 is communicated with the water inlet of the high-pressure pump 15. The water production outlet of the DTRO membrane stack (i.e., an existing Disc Tube Reverse Osmosis membrane module) 16 is communicated with the high-pressure side water inlet of the PX pressure exchanger 17. The high-pressure side water outlet of the PX pressure exchanger 17 is communicated with the water inlet of the concentrated water tank 22, and a pressure relief valve 21 is installed at the high-pressure side water outlet of the PX pressure exchanger 17.

[0032] The PX pressure exchanger 17 can transfer the pressure energy of the high-pressure concentrated water to the low-pressure inlet water, thereby reducing the energy consumption of the high-pressure pump 15, significantly reducing the system energy consumption, and ensuring the efficient and stable operation of the desulfurization wastewater treatment system.

[0033] Specifically combined with Figure 1 , in an embodiment of the present invention, a flow meter 19 is installed at the discharge outlet of the scale inhibitor storage tank 18 to facilitate the statistics and control of the output scale inhibitor dosage.

[0034] Specifically combined with Figure 1 , in an embodiment of the present invention, a laser particle size analyzer 30 is installed at the discharge outlet of the crystal slurry collecting hopper 29.

[0035] In addition, in an embodiment of the present invention, a conductivity monitoring sensor 42 is installed at the water production outlet of the DTRO membrane stack 16. The liquid outlet of the recycled water tank 43 is connected to a backwash water tank 44 through a lift pump. Backwash pipelines are installed on the hydrocyclone 8, the ceramic membrane unit 12, the DTRO membrane stack 16, the PX pressure exchanger 17, and the sludge dewatering machine 40. The water outlet end of the backwash water tank 44 is communicated with each backwash pipeline through a plurality of water delivery pipes, and a backwash pump and a pulse valve are installed on each water delivery pipe to facilitate backwashing of equipment such as the hydrocyclone 8, the ceramic membrane unit 12, the DTRO membrane stack 16, the PX pressure exchanger 17, and the sludge dewatering machine 40 with the purified water produced by the DTRO membrane stack 16.

[0036] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An integrated system for low-cost zero discharge of desulfurized wastewater, characterized in that: It includes an original water tank (1). The water outlet of the original water tank (1) is connected to an acidification reaction tower (4) through an original water pump (2). A chemical dosing mechanism is connected to the acidification reaction tower (4). The overflow port of the acidification reaction tower (4) is connected to a hydrocyclone separator (8). The bottom slag outlet of the hydrocyclone separator (8) is connected to a carbonate crystallization tank (39) through a sludge discharge pump (38). The sludge outlet of the carbonate crystallization tank (39) is connected to a sludge dewatering machine (40). The water outlet of the hydrocyclone separator (8) is connected to a buffer water tank (9). The water outlet of the buffer water tank (9) is connected to a ceramic membrane unit (12) through a first booster pump (10). The water production port of the ceramic membrane unit (12) is connected to a DTRO membrane stack (16) through a high-pressure pump (15). The water production port of the DTRO membrane stack (16) is connected to a reused water tank (43). The concentrated water port of the DTRO membrane stack (16) is connected to a concentrated water tank (22). The water outlet of the concentrated water tank (22) is connected to a two-fluid atomizer (25) through a diaphragm pump (23) and a preheating heat exchanger (24). The air inlet of the two-fluid atomizer (25) is connected to a compressed air source (26). The discharge port of the two-fluid atomizer (25) is connected to a crystal slurry collection hopper (29) through a Z-shaped flue (27) and a cyclone dust collector (28). The discharge port of the crystal slurry collection hopper (29) is connected to a fluidized bed dryer (32) through a pneumatic pump (31). The discharge port of the fluidized bed dryer (32) is connected to a finished product bin (34) through a cyclone separator (33). The air outlets of the cyclone dust collector (28) and the cyclone separator (33) are both connected to a tail gas scrubbing tower (35) through a draft fan. The waste water output port of the tail gas scrubbing tower (35) is connected to the original water tank (1) through a lift pump. The liquid inlet of the high-pressure pump (15) is also connected to a scale inhibitor storage tank (18) through a screw pump (20), and scale inhibitor is stored in the scale inhibitor storage tank (18).

2. The integrated system for low-cost zero discharge of desulfurized wastewater according to claim 1, wherein: The scale inhibitor includes the following components by weight percentage: 20-30% of hydroxyethylidene diphosphonic acid, 15-25% of polyaspartic acid, 10-15% of nanocellulose, 5-10% of ferrous sulfate, and the balance is deionized water.

3. The integrated system for low-cost zero discharge of desulfurized wastewater according to claim 1, wherein: The chemical dosing mechanism includes an acid liquid storage tank (5). The liquid outlet end of the acid liquid storage tank (5) is connected to the acidification reaction tower (4) through a first metering pump (6). A pH transmitter (7) is installed at the overflow port of the acidification reaction tower (4).

4. An integrated system for low-cost zero discharge of desulfurized wastewater according to claim 1, characterized in that: A first pneumatic butterfly valve (3) is installed at the water outlet of the original water pump (2). A sludge concentration sensor (36) and a pneumatic knife gate valve (37) are installed on the slag discharge pipe of the hydrocyclone separator (8). The filtrate output port of the sludge dewatering machine (40) is connected to the original water tank (1) through a pipeline and an electric control ball valve (41).

5. The integrated system for low-cost zero discharge of desulfurized wastewater according to claim 1, wherein: A multi-media filter (11) is installed between the water outlet of the first booster pump (10) and the water inlet of the ceramic membrane unit (12). The concentrated water port of the ceramic membrane unit (12) is communicated with the liquid inlet of the hydrocyclone separator (8) through a pipeline.

6. The integrated system for low-cost zero discharge of desulfurized wastewater according to claim 1, characterized in that: The water production outlet of the ceramic membrane unit (12) is communicated with the water inlet of the high-pressure pump (15) through the PX pressure exchanger (17), and the water production outlet of the DTRO membrane stack (16) is communicated with the water inlet of the concentrated water tank (22) through the PX pressure exchanger (17).

7. An integrated system for low-cost zero discharge of desulfurized wastewater according to claim 6, characterized in that: An SDI sensor (13) and a pneumatic control valve (14) are installed between the water production outlet of the ceramic membrane unit (12) and the low-pressure side water inlet of the PX pressure exchanger (17). The low-pressure side water outlet of the PX pressure exchanger (17) is communicated with the water inlet of the high-pressure pump (15). The water production outlet of the DTRO membrane stack (16) is communicated with the high-pressure side water inlet of the PX pressure exchanger (17). The high-pressure side water outlet of the PX pressure exchanger (17) is communicated with the water inlet of the concentrated water tank (22), and a pressure relief valve (21) is installed at the high-pressure side water outlet of the PX pressure exchanger (17).

8. An integrated system for low-cost zero discharge of desulfurized wastewater according to claim 1, characterized in that: A flowmeter (19) is installed at the discharge outlet of the scale inhibitor storage tank (18).

9. An integrated system for low-cost zero discharge of desulfurized wastewater according to claim 1, characterized in that: A laser particle size analyzer (30) is installed at the discharge outlet of the crystal slurry collection hopper (29).

10. The integrated system for low-cost zero discharge of desulfurized wastewater according to claim 1, characterized in that: A conductivity monitoring sensor (42) is installed at the water production outlet of the DTRO membrane stack (16). The liquid outlet of the reclaimed water tank (43) is connected to the backwash water tank (44) through a lift pump. Backwash pipelines are installed on the hydrocyclone (8), the ceramic membrane unit (12), the DTRO membrane stack (16), the PX pressure exchanger (17), and the sludge dewatering machine (40). The water outlet end of the backwash water tank (44) is communicated with each backwash pipeline through a plurality of water delivery pipes, and a backwash pump and a pulse valve are installed on each water delivery pipe.

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