A circulating water utilization type sewage treatment system

Abstract

The utility model discloses a circulating water utilization type sewage treatment system, including high density hard removal reactor, its water inlet end is linked with raw water pipe, inside from bottom to top is equipped with perforated aeration pipe, first baffle and inclined plate sedimentation area in proper order, is equipped with the slagging-off mouth in the bottom, the utility model discloses a high density hard removal reactor combines electrocatalytic oxidation tank, effectively solved the problem of traditional pretreatment to high salt, high COD, heavy metal removal deficiency, high density hard removal reactor passes through aeration, baffling, inclined plate sedimentation three -section type intensification treatment, removes the hardness and suspended solids in water, creates good condition for subsequent processing, and electrocatalytic oxidation tank utilizes soluble iron anode to produce synergic hydroxyl radical (·OH) oxidation and break down the refractory COD, and also reduces heavy metal ions, makes effluent COD reduce greatly, and heavy metal concentration reduces significantly, and this combined process effectively prevents the frequent pollution of the rear end membrane system, prolongs the service life of the membrane, and reduces the cleaning frequency.

Description

Technical Field

[0001] This utility model relates to the technical field of sewage treatment systems, specifically a circulating water type sewage treatment system. Background Technology

[0002] Currently, it is being used in industrial plants such as chemical, pharmaceutical, and electroplating plants to deeply treat complex wastewater containing high salt, high COD, and heavy metals, and then reuse it for cooling, rinsing, and boiler feedwater. The core principle is to first remove easily degradable pollutants through physicochemical-biological coupling, and then use membrane separation and evaporation crystallization to achieve brine separation and pure water recovery, ultimately forming a closed-loop cycle, reducing fresh water consumption and wastewater discharge.

[0003] Existing circulating water plants mostly adopt the general process of "coagulation sedimentation + biological treatment + RO", which is not targeted enough for the pretreatment of industrial wastewater with high salt, high COD and heavy metal coexistence: coagulation has a low removal rate of dissolved organic matter and heavy metal complexes, and biological treatment is inhibited by high salt, which leads to a shortened fouling cycle of downstream membrane systems to 1-2 weeks, high cleaning frequency and sharp reduction in membrane life; at the same time, heavy metal residues are prone to scale formation on the membrane surface and pollute the product water, which seriously affects the overall treatment efficiency, effluent water quality and operating economy.

[0004] Therefore, a wastewater treatment system based on water recycling is proposed. Utility Model Content

[0005] The purpose of this invention is to provide a wastewater treatment system that utilizes recycled water to solve the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a circulating water utilization type sewage treatment system, including a high-density hardening reactor, whose inlet end is connected to the raw water pipe, and whose interior is provided with perforated aeration pipe, a first baffle plate and an inclined plate sedimentation zone from bottom to top, and a slag discharge port at the bottom.

[0007] The electrocatalytic oxidation tank is connected to the supernatant outlet of the high-density hardening reactor via a first lift pump P. Soluble iron anode plates and titanium-based DSA cathode plates are alternately arranged in the tank, with a plate spacing of 5mm to 15mm. A microporous aeration disc is installed at the bottom of the tank.

[0008] The resin softening tank is filled with a chelated weak acid cationic resin layer, a water distributor is installed below the resin layer, and a brine regeneration inlet is installed on the top of the tank.

[0009] The vibrating membrane filter consists of a housing, a hollow fiber membrane module that can vibrate at high frequency along the axial direction, and a water collection chamber. The membrane pore size is 0.05μm to 0.1μm.

[0010] The high-pressure reverse osmosis unit has its inlet end connected to the product water end of the vibrating membrane filter via a high-pressure pump P, and its concentrate end connected to a multi-effect evaporator crystallizer.

[0011] The recycled water tank is connected to the freshwater end of the high-pressure reverse osmosis unit.

[0012] The control unit is electrically connected to the first booster pump P, the high-pressure pump P, the vibration motor M, and the electrocatalytic oxidation power supply E to achieve linkage control.

[0013] Preferably, the inclined plate sedimentation zone of the high-density hardening reactor has an inclination angle of 55° to 60° and a surface loading of ≤10m. 3 / (m 2 ·h).

[0014] Preferably, the current density of the electrocatalytic oxidation tank is 10 mA / cm². 2 ~30mA / cm 2 The hydraulic retention time is 5 to 15 minutes.

[0015] Preferably, the resin layer of the resin softening tank has a height-to-diameter ratio of 1.5:1 to 2:1, and the regenerated brine concentration is 8% to 12%.

[0016] Preferably, the vibration frequency of the vibrating membrane filter is 20Hz to 50Hz, and the amplitude is 1mm to 3mm.

[0017] Preferably, the high-pressure reverse osmosis device uses a seawater desalination membrane, operates at a pressure of 4MPa to 6MPa, and has a recovery rate of ≥60%.

[0018] Preferably, the multi-effect evaporator crystallizer is a triple-effect forced circulation type, and the secondary steam in the last effect is recycled by mechanical steam recompressor (MVR).

[0019] Compared with the prior art, the beneficial effects of this utility model are:

[0020] 1. This invention effectively solves the problem of insufficient removal of high salt, high COD, and heavy metals by combining a high-density hardening reactor with an electrocatalytic oxidation tank. The high-density hardening reactor removes hardness and suspended solids from the water through a three-stage enhanced treatment process of aeration, baffles, and inclined plate sedimentation, creating favorable conditions for subsequent treatment. The electrocatalytic oxidation tank utilizes soluble iron anodes to generate Fe. 2+ / Fe 3+ The combined process utilizes hydroxyl radicals (·OH) to oxidize and break down recalcitrant COD, while simultaneously reducing heavy metal ions, resulting in a significant reduction in effluent COD and heavy metal concentration. This effectively prevents frequent fouling of the downstream membrane system, extends membrane lifespan, reduces cleaning frequency, ensures stable system operation, and significantly improves overall treatment efficiency and effluent quality.

[0021] 2. This utility model achieves efficient recycling of industrial wastewater, resulting in significant economic and environmental benefits. The system, through optimized configuration of a vibrating membrane filter and a high-pressure reverse osmosis unit, achieves high-recovery-rate freshwater production. The vibrating membrane filter utilizes high-frequency vibration shear force to remove the fouling layer on the membrane surface online, extending the chemical cleaning cycle and reducing operating costs. The high-pressure reverse osmosis unit uses a seawater desalination membrane, and the optimized design of operating pressure and recovery rate further improves the freshwater recovery rate.

[0022] Meanwhile, the concentrated water from the system enters the multi-effect evaporator crystallizer, realizing the resource utilization of salt and reducing hazardous waste discharge. Overall, the freshwater recovery rate of this system can reach over 85%, the power consumption per ton of water is significantly reduced, the investment payback period is short, saving enterprises a lot of water resources and operating costs, while reducing environmental pollution, and has broad application prospects. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the main system structure of the wastewater treatment of this utility model;

[0024] Figure 2 This is a schematic diagram of the main process structure for wastewater treatment according to this utility model;

[0025] Figure 3 This is a schematic diagram of the control system structure of this utility model.

[0026] In the diagram: L0, raw water pipe; 1, high-density hardness removal reactor; 11, first baffle plate; 12, inclined plate sedimentation zone; 13, slag discharge port; 14, high-density hardness removal reactor; 2, electrocatalytic oxidation tank; 21, soluble anode plate; 22, titanium-based DSA cathode plate; 23, microporous aeration disc; 3, resin oxidation tank; 31, chelated weak acid cation exchange resin layer; 32, water distributor; 33, brine regeneration inlet; 4, vibrating membrane filter; 41, shell; 42, hollow fiber membrane module; 43, water collection chamber; 5, high-pressure reverse osmosis device; 6, multi-effect evaporator crystallizer; 8, control unit. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] Example 1: Please refer to Figures 1-3 This utility model provides a technical solution: a circulating water type sewage treatment system, including a raw water pipe L0, through which high-salt, high-COD wastewater (100m³) from coal chemical industry is treated.3 The raw water quality was tested at a scale of / h: TDS 35000 mg / L, COD 1200 mg / L, NH3-N 80 mg / L, Ni 2 +2.5 mg / L, Ca 2+ 900mg / L, SS 300mg / L.

[0029] High-density hardening removal reactor 1, with dimensions of φ3.2m×6m and an effective water depth of 5m;

[0030] Added reagents: 32% NaOH 120mg / L + 99% Na2CO3 350mg / L;

[0031] Perforated aeration pipe 11, air-to-water ratio 5:1, inclined plate angle 60°, surface load 8m. 3 / (m 2 •h), hydraulic retention time 20min;

[0032] Slag discharge port 14 discharges slag once every 4 hours, with a slag moisture content of <75%.

[0033] Electrocatalytic oxidation tank 2 has the following dimensions: 2.5m × 1.2m × 1.5m, with a total of 20 plates and an electrode spacing of 10mm. The power supply E1 outputs DC pulses with a duty cycle of 50%.

[0034] Current density 20 mA / cm 2 Dissolved oxygen in the tank was maintained above 3 mg / L, hydraulic retention time was 10 min, and Fe... 2+ Dosage: 20 mg / L;

[0035] The effluent COD was reduced to 260 mg / L, Ni 2 +<0.1mg / L.

[0036] Resin softening tank 3 has an internal resin layer height of 2m, uses weak acid cationic resin model D113, and has an operating flow rate of 15m / h.

[0037] Its regeneration: 2 BV of 8% NaCl solution, regeneration time 30 min, slow wash 2 BV, fast wash 3 BV, effluent hardness <50 mg / L (calculated as CaCO3).

[0038] Vibrating membrane filter 4 has an internal membrane material of PVDF, a pore size of 0.08μm, and an area of ​​180m². 2 ;

[0039] The vibration motor M1 has a frequency of 35Hz, an amplitude of 2mm, and the transmembrane pressure difference is controlled below 0.03MPa.

[0040] Continued operation for 30 days resulted in a flux decline of less than 5%, and the chemical cleaning cycle was extended to 45 days.

[0041] The high-pressure reverse osmosis unit 5 has SW8040 internal membrane elements, arranged in two stages, with an operating pressure of 5MPa and a recovery rate of 65%.

[0042] Freshwater with TDS 180 mg / L and COD < 10 mg / L is directly reused in circulating cooling water.

[0043] The concentrated water has a TDS of 98,000 mg / L and enters a triple-effect evaporator crystallizer 6. The steam consumption is 0.28 t steam / t water. The sodium sulfate purity is >97%. It is sold externally.

[0044] Results: The system ran continuously for 6 months, with a freshwater recovery rate of 85%, a power consumption of 1.15 kWh per ton of water, and the number of membrane cleanings was reduced from twice a month in the traditional process to once every 4 months.

[0045] Example 2:

[0046] Wastewater containing Cr(VI) from the electroplating industrial park (20m³) 3 / h scale);

[0047] Raw water quality: Cr(VI) 15 mg / L, TDS 25000 mg / L, Cu 2+ 4mg / L, Ni 2 +3mg / L, pH2.5.

[0048] Additional adjustment: Add alkali to adjust the pH to 8.5 before the high-density hardening reactor 1, and add 80 mg / L FeSO4·7H2O to reduce Cr(VI) to Cr(III).

[0049] The remaining steps are the same as in Example 1, except that the current density of the electrocatalytic oxidation tank 2 is adjusted to 15 mA / cm². 2 The effluent Cr(VI) < 0.05 mg / L, Cu 2+ <0.1mg / L, Ni 2 +<0.1mg / L.

[0050] Operating results: After three months of continuous operation, the freshwater recovery rate was 87%, the amount of miscellaneous salts was reduced by 92%, and the Cr(OH)3 slag was transported off-site after being solidified as hazardous waste.

[0051] Example 3:

[0052] With dyeing and printing desizing wastewater (5m 3 / h Modular Demonstration):

[0053] Raw water quality: TDS 18000mg / L, COD 3500mg / L, BOD 5450mg / L, color 2000 times.

[0054] Equipment integration: All units are skid-mounted and integrated into two 12m containers, ready for immediate use upon on-site installation.

[0055] Key adjustment: In its high-density hardening reactor 1, PAC 80mg / L + PAM 1mg / L were added, and SS removal was >95%;

[0056] Electrocatalytic oxidation tank 2 was modified to use a Ti / RuO2-IrO2 anode with a current density of 25 mA / cm². 2 COD decreased to 420 mg / L;

[0057] High-pressure reverse osmosis uses a low-pressure brackish water membrane, operates at a pressure of 2.8 MPa, and has a recovery rate of 75%.

[0058] Operating results: The system produces 90m³ of fresh water per day. 3 Used in the rinsing process, it saves 33,000 cubic meters of tap water annually. 3 The investment payback period is 1.8 years.

[0059] The above scheme is supplemented by the requirement that a maintenance manhole be provided in the inclined plate area of ​​the high-density hardening reactor 1 to facilitate the cleaning of scale.

[0060] The anode of the electrocatalytic oxidation tank 2 is inspected every 6 months, and replaced if the weight loss rate is >5%.

[0061] The regeneration wastewater and reverse osmosis concentrate in resin softening tank 3 are combined and evaporated to ensure zero discharge;

[0062] The motor of the vibrating membrane filter 4 must have an IP65 protection rating to avoid moisture and corrosion.

[0063] The working principle is as follows: This utility model's circulating water utilization wastewater treatment system targets complex industrial wastewater with high salinity, high COD, and heavy metal content, achieving efficient purification and reuse through an innovative multi-stage treatment process. The system's operating principle is as follows:

[0064] Industrial wastewater first enters the high-density hardness removal reactor 1, where it is aerated through perforated aeration pipes 11, baffled by the first baffle plate 12, and settled in the inclined plate sedimentation zone 13. This process removes hardness and suspended solids from the water, reducing the load on subsequent treatments. The treated supernatant is then pumped into the electrocatalytic oxidation tank 2 by the first lift pump P1. Inside the tank, the soluble iron anode plate 21 and the titanium-based DSA cathode plate 22 work synergistically to produce Fe. 2+ / Fe 3+The system utilizes hydroxyl radicals (·OH) to efficiently degrade COD and reduce heavy metal ions, resulting in a significant reduction in effluent COD and heavy metal concentration. Subsequently, the wastewater flows into a resin softening tank 3, where a chelating weak acid cation exchange resin layer 31 further removes residual hardness and trace heavy metals, ensuring stable water quality. The pre-softened water then enters a vibrating membrane filter 4. The hollow fiber membrane module 42, under high-frequency vibration, effectively prevents membrane fouling, extends the cleaning cycle, and ensures filtration efficiency. The filtered water is pressurized by a high-pressure pump P2 and enters a high-pressure reverse osmosis unit 5, where seawater desalination membranes achieve brine separation. The freshwater recovery rate is ≥60%, and the TDS of the permeate is as low as 180 mg / L, allowing for direct reuse in production. The concentrated water then enters a multi-effect evaporator crystallizer 6, where triple-effect forced circulation and a mechanical steam recompressor (MVR) reuse secondary steam, achieving resource utilization of salt and reducing hazardous waste emissions.

[0065] The entire system is uniformly controlled by control unit 8, enabling the coordinated operation of various devices and ensuring efficient and stable processing. This system not only solves the shortcomings of traditional pretreatment, but also improves the freshwater recovery rate and reduces operating costs by optimizing membrane separation and evaporation crystallization processes, thus achieving efficient recycling of industrial wastewater.

[0066] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0067] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A circulating water utilization type sewage treatment system characterized by comprising: The high-density hardness removal reactor (1) is connected with raw water pipe (L0) at its water inlet end, and is internally provided with perforated aeration pipe (11), first baffle (12) and inclined plate sedimentation zone (13) from bottom to top in sequence, and is provided with slag discharge port (14) at its bottom; The electro-catalytic oxidation tank (2) is connected with supernatant outlet of the high-density hardness removal reactor (1) through first lifting pump (P1), and is alternately provided with soluble iron anode plate (21) and titanium-based DSA cathode plate (22) in the tank, the distance between the plates is 5mm-15mm, and the tank is provided with micro-porous aeration disc (23) at its bottom; The resin softening tank (3) is internally filled with chelate type weak acid cation resin layer (31), and is provided with water distributor (32) below the resin layer, and is provided with salt water regeneration inlet (33) at its top; The vibrating membrane filter (4) is composed of shell (41), hollow fiber membrane assembly (42) which can be axially high-frequency vibrated, and water collecting cavity (43), and has membrane pore size of 0.05μm-0.1μm; The high-pressure reverse osmosis device (5) is connected with water production end of the vibrating membrane filter (4) through high-pressure pump (P2) at its water inlet end, and is connected with multi-effect evaporation crystallizer (6) at its concentrated water end; The reclaimed water tank (7) is connected with fresh water end of the high-pressure reverse osmosis device (5); The control unit (8) is electrically connected with first lifting pump (P1), high-pressure pump (P2), vibrating motor (M1) and electro-catalytic oxidation power supply (E1) to realize linkage control.

2. The recirculating, water conservation sewage treatment system of claim 1, wherein: The angle of the inclined plate sedimentation zone (13) of the high-density hardening reactor (1) is 55-60°, and the surface load is ≤10 m 3 / (m 2 ·h).

3. The recirculating, water conservation sewage treatment system of claim 1, wherein: The current density of the electro-catalytic oxidation tank (2) is 10 mA / cm 2 ~ 30 mA / cm 2 , and the hydraulic retention time is 5 min ~ 15 min.

4. The recirculating, water conservation sewage treatment system of claim 1, wherein: The resin layer of the resin softening tank (3) has height-diameter ratio of 1.5:1-2:1, and the concentration of the regeneration salt water is 8%-12%.

5. The recirculating, water conservation sewage treatment system of claim 1, wherein: The vibrating frequency of the vibrating membrane filter (4) is 20Hz-50Hz, and the amplitude is 1mm-3mm.

6. The recirculating, water conservation sewage treatment system of claim 1, wherein: The high-pressure reverse osmosis device (5) adopts seawater desalination membrane, and has operation pressure of 4MPa-6MPa and recovery rate of ≥60%.

7. The recirculating, water conservation sewage treatment system of claim 1, wherein: The multi-effect evaporation crystallizer (6) is three-effect forced circulation type, and the secondary steam of the last effect is reused through mechanical vapor recompression machine (MVR).

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