Desalted water preparation system and process method based on multi-source complex steel wastewater

Abstract

In order to realize effective utilization of multi-source complex wastewater, reduce water taking cost and pollution discharge cost and realize double harvest of economic benefits and environmental benefits of enterprises, the invention provides a process and technology for multi-source complex wastewater by adopting aeration, a high-density sedimentation tank, a V-shaped filter tank, ultrafiltration, primary reverse osmosis and secondary reverse osmosis according to actual conditions of the enterprises. Desalted water preparation is achieved, supply of a 1549 heating furnace, an oriented silicon steel area, a water supply pipe network and the like is met, and green development and sustainable development of enterprises are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, and particularly relates to a salt-removing water preparation system and process method based on multi-source complex steel wastewater. BACKGROUND

[0002] Steel enterprises are not only water consumers, with water consumption of about 2-5 cubic meters per ton of steel, especially in water-deficient areas, water resources are more strained, and steel enterprises are also water dischargers, generating a large amount of wastewater every year, the production wastewater contains heavy metals, cyanide, oil, suspended solids, etc., direct discharge will pollute water bodies, soil, harm the ecological system and human health, toxic substances in water may accumulate through the food chain, leading to a decline in biodiversity, and even causing long-term environmental problems.

[0003] TISCO also presents the same problem, especially in the 1549 rolling area, not a single source of wastewater discharge, the water quantity of Jianshan post-treatment discharge is about 6000m3 / d, the water quantity of hot continuous rolling 1549 turbid ring system discharge is about 1200m3 / d, and the industrial circulating water pipe network also passes through the area, and the water supplement quantity meets the objective demand of water production quantity.

[0004] After wastewater treatment, not only can the wastewater be reused, but also the water taking cost and pollution charge can be reduced, realizing double harvest of enterprise economic benefits and environmental benefits, and according to the actual situation of the enterprise, it is urgent to invent a salt-removing water preparation system and process technology based on multi-source and complex steel wastewater, to solve the actual problems.

[0005] The present application provides a salt-removing water preparation system and process technology, which can not only realize wastewater discharge up to standard, but also meet the actual water resource needs of TISCO, and the effluent is supplied to the 1549 heating furnace and the oriented silicon steel and the regional pipe network for water supplement. SUMMARY

[0006] The present application is aimed at the above problems, and provides a salt-removing water preparation system and process method based on multi-source and complex steel wastewater.

[0007] The object of the present application is achieved by a multi-source complex steel wastewater desalination water preparation system and process method. The system is configured with one adjusting pool, two high-density sedimentation pools, four V-type filter pools, one concrete ultrafiltration water pool, five groups of ultrafiltration, three self-cleaning filters, seven security filters, four groups of first-stage reverse osmosis, and three groups of second-stage reverse osmosis, and is equipped with a dosing and chemical cleaning system. (1) The adjusting pool: treatment water, industrial circulating water, and filter backwash water flow into the adjusting pool as the water source, and are aerated by a fan. Sodium hypochlorite is stored in a chemical tank and is added to the inlet pipe of the pretreatment adjusting pool by a dosing pump. The sodium hypochlorite added to the inlet water oxidizes Fe 2+ into Fe 3+ , and the membrane pressure difference is controlled below 0.30 Mpa. Then the water is sent to the high-density sedimentation pool by a lifting pump. (2) The high-density sedimentation pool: the water treated by the adjusting pool is evenly distributed to each high-density sedimentation pool through a water distribution channel for physicochemical treatment. The high-density sedimentation pool is divided into three units, i.e., a reaction pool, a pre-sedimentation-concentration pool, and an inclined tube separation pool. Sodium hypochlorite with an effective concentration of 5-10 mg / l is continuously added to the inlet for 24 hours. In the reaction pool, PAC (polyaluminum chloride) with an effective concentration of 15-35 mg / l is continuously added to the reaction area for 24 hours, and PAM (polyacrylamide) with an effective concentration of 2-6 mg / l is continuously added for 24 hours. The reaction pool is divided into two parts, one is a coagulation stirring reaction pool with a stirring speed of 30-50 Hz, and the other is a coagulation plug flow reaction pool with a stirring speed of 10-30 Hz, to ensure that the entire reaction pool obtains a large amount of high-density and homogeneous flocculation. In the pre-sedimentation-concentration pool, the flocculation moves at a speed of 10-15 M 3 / h in the large-area pre-sedimentation area, so that most of the suspended solids are precipitated and concentrated in this area. Part of the concentrated sludge is pumped back to the inlet of the reaction pool by a backflow sludge pump. The concentration area is divided into two layers, one layer above the conical circulating cylinder and one layer below the conical circulating cylinder. The remaining sludge is pumped out from the bottom of the pre-sedimentation pool to the concentration pool. In the inclined tube separation pool, the remaining flocculation is removed in the inclined tube sedimentation area. The effluent after sedimentation is collected in a collection tank, and the flocculation is accumulated in the lower part of the clarification tank, and the formed sludge is also concentrated in this area. The sludge is collected by gravity or scraped off or circulated to the front part of the reaction pool. The high-density sedimentation pool adopts the inclined tube sedimentation and sludge circulation mode, and two high-density sedimentation pools are equipped with two sludge circulation pumps, two sludge discharge pumps, and two standby pumps. (3) The V-type filter pool: the V-type filter pool has four pools, with a single pool filtration water volume of 150-200 m 3 / h and a filtration speed of 5-7 m / h. Each pool has 20-30 filter plates with an area of 1-2.5 m 2Each filter plate has 40-50 filter caps; sand filter material is used, the effective particle size of sea sand is 0.95-1.35 mm, the filter layer is 1.3-1.6 m thick, the supporting layer is coarse sea sand 0.1-0.2 m thick, the particle size is 2-4 mm, the water produced by the high-density sedimentation tank is self-flowing to the subsequent V-shaped filter tank for filtration, first flows into the overflow weir at the front end of each filter tank through the water distribution channel, the overflow water flows into the filter grid through the water distribution port of the V-shaped water inlet groove, flows through the filter material under the action of water pressure, enters the bottom space through the long handle filter head, overflows into the V-shaped filter water tank through the clean water pipe, water seal well and overflow well, when the predetermined backwashing period or the predetermined filtration water head loss is reached, the filter tank is backwashed by the set backwashing pump and fan, the backwashing process of the V-shaped filter tank adopts "air backwashing-air and water backwashing simultaneously-water backwashing", three steps, the backwashing water source comes from the V-shaped filter water tank, provided by three backwashing water pumps, the air source is provided by three fans, the operation and backwashing process of the V-shaped filter tank are automatically controlled by the PLC system, the V-shaped filter tank water tank is provided with an ultrafiltration water pump, which provides flow and pressure stable water for the subsequent ultrafiltration system, the flow is 150-240 m 3 / h, the pressure is 1.5-2.5 MPa, the ultrafiltration water pump has three units, each unit has an output of 400 m 3 / h, the lift is 45 meters, of which two units are frequency conversion controlled; (4) ultrafiltration system: the water produced by the V-shaped filter tank is pumped out from the V-shaped filter water tank by the ultrafiltration water pump, and after being pressurized through the self-cleaning filter, enters the ultrafiltration membrane device for treatment, and the produced water is self-flowing into the ultrafiltration water tank, the pressure is 0.3-1 MPa; (5) reverse osmosis system: the water in the ultrafiltration water tank is pressurized to 0.9-1.6 MPa by a primary reverse osmosis booster pump, enters a primary security filter, hydrochloric acid, scale inhibitor and reducing agent are added at the inlet and outlet of the primary security filter, respectively, the water outlet of the primary security filter is pressurized to 0.85-1.5 MPa by a primary high-pressure pump, and enters a primary reverse osmosis device for desalination treatment, the desalinated water enters a primary desalination water tank, most of the primary desalination water is supplied outside by a primary desalination water pump, and the other part is pressurized to 0.6-0.8 MPa by a secondary reverse osmosis device booster pump, passes through a secondary security filter and a secondary high-pressure pump for pressure boosting, and then enters a secondary reverse osmosis device for secondary desalination treatment, the produced water enters a secondary desalination water tank, and is output by a secondary desalination water pump, the concentrated water of the primary reverse osmosis device is directly discharged, and the concentrated water is recycled to the intermediate water tank.

[0008] The ultrafiltration system is provided with three self-cleaning filters, two for use and one for standby, five sets of ultrafiltration devices, and one set of ultrafiltration backwashing and EFM / CIP chemical cleaning system.

[0009] The beneficial effects of the present application are: after the water of Xianshan post-treatment, the drainage of 1549 turbidity ring filter, the circulating water of pipe network flows into the adjusting pool, is aerated to remove iron, is filtered through the high-density sedimentation tank and V filter, is ultra-filtered, is first reverse osmosis, and is second reverse osmosis, the effluent is supplied to the 1549 heating furnace and the oriented silicon steel area pipe network supply. The first reverse osmosis concentrated brine is supplied to the ironmaking yard dust removal, the second reverse osmosis concentrated water is recycled, the sludge of the high-density sedimentation tank is discharged to the 1549 sludge treatment system, the ultrafiltration and reverse osmosis chemical cleaning water is neutralized and then discharged, and the drainage of other systems is all recycled to the adjusting pool at the front end of the system for recycling, so that the sustainable utilization of water resources is realized, the consumption of fresh water is reduced, and the green development and sustainable development goals of the enterprise are realized. BRIEF DESCRIPTION OF DRAWINGS

[0010] The present application will be further described below in combination with the drawings.

[0011] Figure 1 The system flowchart of the present application. DETAILED DESCRIPTION

[0012] The main process is "aeration + high-density sedimentation tank + V filter + ultrafiltration + first reverse osmosis + second reverse osmosis", the system adopts PLC control, realizes automatic control and interlocking function of the system and each device, and can adopt automatic and manual control in each process unit.

[0013] The water inflow is aerated to sufficiently nitrate the iron in the water, oxidize the divalent iron to trivalent iron, form a precipitate in the subsequent sedimentation tank for removal, add flocculants and coagulants in the high-density sedimentation tank, and use mud backflow to make suspended solids and organic matter form large floc to be precipitated and removed, and the V filter can effectively remove fine suspended solids and the like, thereby reducing the operation load of the subsequent membrane system and prolonging the service life of the ultrafiltration and reverse osmosis membrane elements. The external pressure type ultrafiltration is adopted to further remove impurities and organic matter in the water, ensure the stable operation of the reverse osmosis, remove the salt in the water through the reverse osmosis, and prepare desalted water.

[0014] The system is configured with one adjusting pool, two high-density sedimentation tanks, four V filters, one newly-built concrete ultrafiltration water pool, five groups of ultrafiltration, three self-cleaning filters, seven security filters, four groups of first reverse osmosis, and three groups of second reverse osmosis, and is matched with a dosing system, a chemical cleaning system and the like.

[0015] The preparation system and process technology mainly include: (1) adjusting pool: the Xianshan post-treatment water and industrial circulating water (a small part of filter backwash water) are taken as the water source to flow into the adjusting pool, are aerated through the Roots blower, oxidize the divalent iron ions in the water, and then are sent into the high-density sedimentation tank by the lifting pump.

[0016] Main equipment: aeration Roots blower: to provide aeration tank flow, pressure stable aeration gas source. Output flow 25.6 m3 / min, pressure 45 KPa, 2, 1 for 1; booster pump: to provide subsequent high-density sedimentation tank flow, pressure stable system raw water, flow 450 m3 / h, head 18 meters, 2 for 1, of which 2 frequency control (1#, 2#).

[0017] (2) high-density sedimentation tank: raw water through the distribution channel is evenly distributed to each seat high-density sedimentation tank for materialized treatment, high-density sedimentation tank is divided into three units, reaction, pre-sedimentation - concentration and inclined tube separation. Inlet to add an appropriate amount of NaCIO, used to avoid the subsequent system of bacteria and other microorganisms, so as to form a biological pollution of ultrafiltration and reverse osmosis membrane.

[0018] Reaction tank: first in the reaction zone to add flocculant, coagulant aid, reaction tank is divided into two parts, one is a rapid mixing coagulation stirring reaction tank, the other is a slow coagulation plug flow reaction tank, each pool shape is an internal connected two areas. To ensure that the entire reaction tank (mixing and plug flow reactor) quickly obtain a large number of high-density, homogeneous flocculation. The amount of coagulant added according to the water inflow and water quality for timely adjustment.

[0019] Pre-sedimentation - concentration tank: when entering the area of the pre-sedimentation zone, flocculation moves slowly, to avoid the formation of flocculation breakage and vortex formation, also makes the vast majority of suspended solids in the area and concentrate. Part of the concentrated sludge in the thickening tank and pumped back to the inlet of the reaction tank. Concentration zone can be divided into two layers: one layer on the conical circulating cylinder, one layer under the conical circulating cylinder, from the pre-sedimentation tank to the bottom of the thickening tank to extract the remaining sludge.

[0020] Inclined tube separation tank: in the inclined tube sedimentation zone to remove the remaining flocculation. The effluent after sedimentation is collected by a collection tank system, and the flocculation is accumulated in the lower part of the clarifier, and the sludge formed is also concentrated in this area. The sludge is collected by gravity or scraped or recycled to the front of the reaction tank. High-density sedimentation tank is a new type of high-efficiency clarification process, which adopts inclined tube sedimentation and sludge circulation mode. The design total treatment capacity of two high-density sedimentation tanks is 750 m 3 / h, with 2 sludge circulation pumps and 2 sludge discharge pumps and 2 standby pumps (both can be used as standby circulation pump and discharge pump).

[0021] (3) V-type filter tank: V-type filter tank is a form of rapid filter tank, which is named because its inlet tank shape is V-shaped. The bottom of the inlet tank is provided with a row of small holes, which can be used for water inlet during filtration and horizontal cleaning water supply during washing. V-type filter tank mainly functions to further reduce the suspended solids and turbidity of high-density sedimentation tank effluent, and to reduce the operating load of subsequent ultrafiltration system, thereby prolonging the service life of ultrafiltration membrane.

[0022] The V-type filter tank uses thicker filter material and thicker filter layer to increase the filtration cycle. Since the filter layer does not expand during backwashing, the particle size distribution of the entire filter layer is basically uniform in the depth direction, and no hydraulic grading phenomenon occurs. That is, the so-called "homogeneous filter material" increases the pollution capacity of the filter layer. The filter tank has four tanks, and the single tank has a filtration water volume of 187.5 m3 / h, and the filtration speed is 7 m / h; each tank has 28 filter plates (an area of 1 m*1 m), each filter plate has 49 filter caps, and there are a total of 28*4*49=5488 filter caps; sand filter material is used, the effective particle size of sea sand is 0.95-1.35 mm, the filter layer is about 1.5 m thick, and the supporting layer is about 0.1 m thick with a particle size of 2-4 mm. The water produced by the high-density sedimentation tank flows to the subsequent V-type filter tank for filtration. First, the water flows into the front overflow weir of each filter tank through the water distribution channel, overflows out of the water through the V-type water inlet, flows into the filter through the water distribution port of the V-type water inlet, flows through the filter material under the action of water pressure, enters the bottom space through the long handle filter head, and overflows into the V-filter water production tank through the clean water pipe, water seal well, and overflow well.

[0023] When the predetermined backwashing cycle or the predetermined filtration water head loss is reached, the filter tank is backwashed by the set backwashing pump and Roots blower. The V-type filter tank backwashing process adopts "air flushing-air and water simultaneous backwashing-water flushing" three steps. The backwashing water source comes from the V-filter water production tank, which is provided by 3 backwashing water pumps (2 in use and 1 in standby), and the air source is provided by 3 Roots blowers (2 in use and 1 in standby). The operation, backwashing and other processes of the V-type filter tank are automatically controlled by PLC.

[0024] The V-filter water production tank is provided with an ultrafiltration water supply pump, which provides flow and pressure stable water for the subsequent ultrafiltration system. The ultrafiltration water supply pump has a capacity of 400 m3 / h and a head of 45 meters, and two of them are frequency-controlled.

[0025] (4) Ultrafiltration system: The water produced by the high-density sedimentation tank and the V-type filter tank is pumped out from the V-filter water production tank by the ultrafiltration water supply pump, and enters the ultrafiltration membrane device after passing through the self-cleaning filter under pressure. The water produced by the ultrafiltration system is self-flowing into the ultrafiltration water production tank. The system is provided with 3 self-cleaning filters, 2 in use and 1 in standby, 5 sets of ultrafiltration devices (SMT600-80), and 1 set of ultrafiltration backwashing and EFM / CIP chemical cleaning system.

[0026]

[0027]

[0028]

[0029] (5) Reverse osmosis system: The main purpose of the reverse osmosis system is to remove salt and small substances such as organic matter and colloids remaining in the ultrafiltration water, so that the produced water meets the user's requirements.

[0030] The water in the intermediate water tank is pressurized by a primary reverse osmosis lifting pump into a primary 5 μm security filter, and an appropriate amount of hydrochloric acid, scale inhibitor and reducing agent is added to the inlet and outlet of the security filter, respectively. The water out of the security filter is pressurized by a primary high-pressure pump into a primary reverse osmosis device for desalination treatment, and the desalination product water is introduced into a primary desalination water tank, most of which is supplied by a primary desalination water pump, and the other part is pressurized by a secondary RO lifting pump, and then introduced into a secondary reverse osmosis device for secondary desalination treatment after being pressurized by a secondary 5 μm security filter and a secondary high-pressure pump, and the product water is introduced into a secondary desalination water tank and supplied by a secondary desalination water pump. The concentrated water of the primary RO device is directly discharged, and the concentrated water of the secondary RO device is returned to the intermediate water tank for recycling. A chemical cleaning system is arranged in the reverse osmosis system, and the cleaning water source is from the reverse osmosis product water, and the cleaning waste water is collected and discharged. In operation, the RO membrane may be contaminated or blocked by inorganic scale, colloid, microorganisms, metal oxides and the like. These substances deposited on the membrane surface will cause the permeation of the RO membrane to decrease and the desalination rate to decrease. In order to restore the permeation and desalination performance of the RO membrane, the RO unit needs to be cleaned regularly. The reverse osmosis cleaning system includes a security filter (VT-6-DN550SS), a cleaning tank (steam heating, vertical cylinder 10M3) and supporting accessories, which can be manually cleaned offline. The NaHS03 reducing agent is added to the security filter inlet pipe, mainly used for reducing the residual chlorine control of the primary reverse osmosis device inlet water, the addition amount is 3 mg / L, the HCI hydrochloric acid is added, mainly used for adjusting the PH of the primary reverse osmosis inlet water, the addition amount is 12 mg / L, and the NaOH is added for cleaning, mainly used for controlling the pollution of the ultrafiltration inlet water, and the addition amount is 0.3-1 mg / L.

[0031]

[0032] The above is an implementation case adopted in the six-membrane production line of TISCO, and the system has a daily processing capacity of 18000 m 3 The wastewater, the primary desalination water production capacity is 480 m3 / h, and the secondary desalination water production capacity is 180 m3 / h, which can be adjusted according to the external supply demand. After the water is aerated to remove iron, filtered by a high-density sedimentation tank and a V-type filter, it is subjected to ultrafiltration, primary reverse osmosis and secondary reverse osmosis, and the effluent is supplied to a 1549 heating furnace and a directional silicon steel area pipe network. The primary reverse osmosis concentrated brine is supplied to a ironmaking yard dust removal, and the secondary reverse osmosis concentrated water is recycled. The sludge discharged from the high-density sedimentation tank is discharged to a 1549 sludge treatment system, and the chemical cleaning water of the ultrafiltration and reverse osmosis is neutralized and then discharged. The water discharged from other systems is all recycled to a regulating tank at the front end of the system for recycling, so that the water resources can be used sustainably.

[0033] The above only describes specific embodiments of the present application, but the structural features of the scope of protection of the present application are not limited thereto, and any person skilled in the art can make changes or modifications in the field of the present application, which are all covered by the patent scope of the present application.

Claims

1. A system and process for preparing demineralized water from complex multi-source steelmaking wastewater, characterized in that: This system is equipped with one equalization tank, two high-density sedimentation tanks, four V-type filters, one concrete ultrafiltration water production tank, five ultrafiltration units, three self-cleaning filters, seven security filters, four primary reverse osmosis units, three secondary reverse osmosis units, and a chemical dosing and cleaning system. (1) Equalization Tank: Treated water, industrial circulating water, and filter backwash water flow into the equalization tank as incoming water sources. Aeration is carried out by a blower. At the same time, sodium hypochlorite is stored in a chemical tank and added to the inlet pipe of the pretreatment equalization tank through a dosing pump. The addition of sodium hypochlorite to the inlet water will reduce Fe 2+ Oxidized to Fe 3+ The membrane pressure differential is controlled below 0.30 MPa, and then pumped into a high-density sedimentation tank by a lift pump. (2) High-density sedimentation tank: The raw water, i.e. the water after the equalization tank, is evenly distributed to each high-density sedimentation tank through the distribution channel for physicochemical treatment. The high-density sedimentation tank is divided into three units: reaction, pre-sedimentation-concentration and inclined tube separation. NaClO with an effective concentration of 5~10mg / l is added at the inlet for 24 hours. Reaction tank: PAC (polyaluminum chloride) with an effective concentration of 15~35mg / l is added in the reaction zone for 24 hours. PAM (polyacrylamide) with an effective concentration of 2~6mg / l is added for 24 hours. The reaction tank is divided into two parts: one is a coagulation stirring reaction tank with a stirring speed of 30-50Hz, and the other is a coagulation plug flow reaction tank with a stirring speed of 10-30Hz to ensure that the entire reaction tank obtains a large amount of high-density, homogeneous flocs. Pre-sedimentation-concentration tank: When entering the large pre-sedimentation zone, the floc moving speed is 10-15M. 3 / h, so that most of the suspended solids settle and concentrate in this area. Part of the concentrated sludge is pumped out of the thickening tank and sent back to the inlet of the reaction tank using a return sludge pump. The thickening area is divided into two layers: one layer above the conical circulation cylinder and one layer below the conical circulation cylinder. The remaining sludge is pumped out from the bottom of the pre-sedimentation tank to the thickening tank. Inclined tube separation tank: The remaining flocs are removed in the inclined tube sedimentation zone. The effluent after sedimentation is collected by a collection tank. The flocs accumulate in the lower part of the clarifier. The sludge formed is also concentrated in this area. The sludge is collected by its own weight, scraped off, or circulated to the front of the reaction tank. The high-density sedimentation tank adopts inclined tube sedimentation and sludge circulation. Two high-density sedimentation tanks are equipped with two sludge circulation pumps, two sludge discharge pumps, and two spare pumps. (3) V-type filter: The V-type filter consists of four tanks, with a single tank filtration capacity of 150-200 m³ / h. 3 The filtration rate is 5-7 m / h; each tank has 20-30 filter plates with an area of ​​1-2.5 m². 2 Each filter plate has 40-50 filter caps; sand filter media is used, with sea sand having an effective particle size of 0.95-1.35mm and a filter layer thickness of 1.3-1.6m. The support layer of coarse sea sand has a thickness of 0.1-0.2m and a particle size of 2-4mm. The permeate from the high-density sedimentation tank flows by gravity to the subsequent V-type filter for filtration. First, it flows into the overflow weir at the front of each filter cell through the distribution channel. The overflow water flows into the filter cell through the distribution port of the V-shaped inlet channel. Under water pressure, it flows through the filter media, enters the bottom space through the long-handled filter head, and overflows into the V-type filter permeate through the clear water pipe, water seal well, and overflow well. In the water tank, when the predetermined backwash cycle or predetermined filtration head loss is reached, the filter tank undergoes air and water backwashing via a set backwash pump and blower. The V-type filter tank backwashing process adopts a three-step process: "air flushing - simultaneous air and water backwashing - water flushing". The backwash water source comes from the V-type filter product water tank and is supplied by 3 backwash water pumps, while the air source is supplied by 3 blowers. The operation and backwashing process of the V-type filter tank are automatically controlled by a PLC system. The V-type filter product water tank is equipped with an ultrafiltration feed water pump, which provides stable flow and pressure water to the subsequent ultrafiltration system, with a flow rate of 150-240Mb. 3 / h, pressure 1.5-2.5MPa, there are 3 ultrafiltration feed water pumps, each with a capacity of 400m³ / h. 3 / h, head 45 meters, including 2 frequency converters; (4) Ultrafiltration system: The permeate filtered by the V-type filter is drawn from the V-filter permeate tank by the ultrafiltration feed water pump, passes through the self-cleaning filter under pressure and enters the ultrafiltration membrane device for treatment. The permeate flows into the ultrafiltration permeate tank by gravity. The pressure is 0.3-1MPa. (5) Reverse osmosis system: The water in the ultrafiltration permeate tank is pressurized to 0.9-1.6MPa by the first-stage reverse osmosis booster pump and enters the first-stage security filter. Hydrochloric acid, scale inhibitor and reducing agent are added to the inlet and outlet of the first-stage security filter respectively. The water from the first-stage security filter is then pressurized to 0.85-1.5MPa by the first-stage high-pressure pump and enters the first-stage reverse osmosis unit for desalination. The desalinated permeate enters the first-stage demineralized water tank. Most of the first-stage demineralized water is supplied externally by the first-stage demineralized water pump. The other part is pressurized to 0.6-0.8MPa by the second-stage reverse osmosis unit booster pump. After being pressurized by the second-stage security filter and the second-stage high-pressure pump, it enters the second-stage reverse osmosis unit for secondary desalination. Its permeate enters the second-stage demineralized water tank and is transported externally by the second-stage demineralized water pump. The concentrate from the first-stage reverse osmosis unit is directly discharged and recycled back to the intermediate water tank. The reverse osmosis system is equipped with a chemical cleaning system. The cleaning water source comes from the reverse osmosis permeate. The cleaning wastewater is collected and discharged.

2. The demineralized water preparation system and process for complex steelmaking wastewater based on multi-source sources as described in claim 1, characterized in that: The ultrafiltration system is equipped with 3 self-cleaning filters, two in use and one on standby, 5 ultrafiltration units, and one ultrafiltration backwashing and EFM / CIP chemical cleaning system.

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