Concentration and filtration process for membrane separation of electroplating wastewater

Abstract

The invention discloses a concentration and filtration process for electroplating wastewater membrane separation, and relates to the field of electroplating wastewater treatment.The concentration and filtration process comprises the steps that S1, channel classification treatment is conducted, specifically, a high-precision camera and a sensor array are installed, and the size, shape and color of suspended solid particles in electroplating wastewater and the characteristic spectrum of heavy metal ions and organic matter are monitored in real time; rapidly analyzing the collected data, accurately classifying the electroplating wastewater into substreams with different pollution degrees and components, and discharging the substreams into different channels for treatment according to classification; s2, unified filtration treatment; s3, performing ultrafiltration membrane treatment; s4, reverse osmosis membrane treatment. According to the concentration and filtration process for membrane separation of the electroplating wastewater, through a multi-stage fine physical filtration and membrane separation technology, the use of chemical agents is effectively reduced, the generation of chemical sludge is reduced, the purification and concentration of the electroplating wastewater can be efficiently realized, and the purposes of water resource reuse and heavy metal recovery are achieved.

Description

Technical Field

[0001] The invention relates to the field of electroplating wastewater treatment, and in particular to a concentration and filtration process for electroplating wastewater membrane separation. Background Art

[0002] Electroplating wastewater refers to various wastewater generated in the electroplating production process, mainly from the cleaning of plated parts, filtration of plating solution, leakage of plating tanks and other links. Its composition is relatively complex, usually containing a large amount of heavy metal ions, such as chromium, nickel, copper, zinc, cadmium, etc. It may also contain acids, alkalis, cyanides and some organic additives. These heavy metal ions are toxic and can cause serious harm to the ecological environment and human health. For example, chromium ions can affect the human respiratory system, digestive system, etc., and long-term contact may cause cancer; nickel ions may cause skin allergies, respiratory diseases, etc. Acid and alkaline wastewater will change the pH value of the water body, destroy the living environment of aquatic organisms, and affect the self-purification ability of the water body. Cyanide is highly toxic and even a small amount can cause fatal damage to organisms.

[0003] When treating electroplating wastewater, there are usually steps of coagulant, coagulant aid and flocculation, which will produce chemical sludge. While the overall cost increases, the subsequent pollution is also greater.

[0004] Therefore, it is necessary to propose a concentration and filtration process for electroplating wastewater membrane separation to solve the above problems. Summary of the invention

[0005] The main purpose of the present invention is to provide a concentration and filtration process for membrane separation of electroplating wastewater, which can effectively solve the problems in the background technology.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A concentration and filtration process for membrane separation of electroplating wastewater, comprising the following steps:

[0008] S1: Channel classification processing, install high-precision cameras and sensor arrays to monitor the size, shape, color of suspended solid particles in electroplating wastewater and the characteristic spectra of heavy metal ions and organic matter in real time, quickly analyze the collected data, accurately classify the electroplating wastewater into sub-flows with different pollution levels and components, and discharge them into different channels for treatment according to the classification;

[0009] S2: Unified filtration treatment, the electroplating wastewater after being treated in different channels is collected uniformly. The wastewater first enters the sand filter tank, which is filled with quartz sand of different particle sizes. The wastewater is 0.3-0.5m 3 / h passes through the sand filter to intercept sand, dust and metal debris in electroplating wastewater;

[0010] After sand filtration, the electroplating wastewater enters the activated carbon filter. The activated carbon uses granular coconut shell activated carbon to adsorb organic matter, residual chlorine and other impurities in the electroplating wastewater. The empty bed contact time of the activated carbon filter is controlled at 15-20 minutes. The electroplating wastewater slowly penetrates the activated carbon layer and removes some organic pollutants through adsorption.

[0011] The electroplating wastewater from the activated carbon filter enters the microfiltration system. The microfiltration membrane uses an inorganic ceramic membrane with a pore size of 0.1-0.2μm to remove the remaining tiny particles, bacteria and other impurities in the electroplating wastewater. The microfiltration system uses a dead-end filtration method with an operating pressure of 0.1-0.15MPa. The wastewater flow is controlled by a constant flow pump with a flow rate of 0.8-1.2m 3 / h;

[0012] S3: Ultrafiltration membrane treatment. The ultrafiltration membrane uses a hollow fiber ultrafiltration membrane made of hydrophilic polyethersulfone. The ultrafiltration system adopts a cross-flow filtration method with a cross-flow velocity of 1.5-2m / s. The cross-flow velocity is maintained by a circulating pump to form a shear force on the membrane surface to reduce the deposition of pollutants on the membrane surface. The operating pressure is controlled at 0.18-0.22MPa, and the operating temperature is maintained at 20-25℃. A heat exchanger is set in the water inlet pipe to adjust the temperature of the electroplating wastewater. During operation, backwashing is performed every 45-60 minutes. Pure water is used for backwashing. The backwashing pressure is 0.1-0.12MPa and the backwashing time is 40-60 seconds to remove pollutants on the membrane surface. The permeate enters the next stage of reverse osmosis membrane treatment, and the concentrate returns to the microfiltration system for further treatment.

[0013] S4: Reverse osmosis membrane treatment. The reverse osmosis membrane adopts a rolled reverse osmosis membrane made of composite polyamide. The first-stage reverse osmosis operating pressure is controlled at 1.8-2.0MPa, the second-stage operating pressure is controlled at 1.0-1.2MPa, and the operating temperature is maintained at 22-24°C. During operation, chemical cleaning is performed every 1.5-2 hours to remove dirt and scaling substances on the membrane surface. After the electroplating wastewater is treated with the reverse osmosis membrane, fresh water and concentrate are finally produced.

[0014] Preferably, in S1, wastewater flows mainly composed of copper, nickel and zinc are distinguished according to the particle size and glossiness of metal particles in the electroplating wastewater; wastewater areas containing high concentrations of organic matter are identified according to the fluorescence characteristic spectrum of organic matter, and customized pre-filtration paths are designed for wastewaters with different diversions. For wastewater with high content of large-particle metal impurities, it is guided to enter a magnetic separation channel, in which a high-strength permanent magnet array is arranged, and the magnetic difference of metal particles is used to efficiently adsorb and separate magnetic metal particles such as iron, cobalt and nickel; for electroplating wastewater containing high concentrations of organic matter and tiny suspended impurities, it is made to enter a multi-layer gradient microporous filtration unit, which is composed of stainless steel sintered microporous filter materials with pore sizes of 50μm to 5μm arranged in sequence, and the flow rate is 0.2-0.3m 3 / h, used to gradually intercept impurities of different sizes.

[0015] Preferably, in S2, the particle size of the quartz sand in the sand filter increases gradually from top to bottom, the particle size of the top fine sand is 0.4-0.6 mm, the particle size of the middle sand is 0.8-1.2 mm, and the particle size of the bottom coarse sand is 2-3 mm. The sand filter is backwashed regularly, and the backwashing intensity is 12-15 L / (m 2 ·s), and the backwash time is 5-8 minutes to remove impurities accumulated in the sand layer.

[0016] Preferably, in S2, during the filtration process of the microfiltration system, when the transmembrane pressure difference reaches 0.08-0.1 MPa, the microfiltration membrane is backwashed, and the backwashing adopts a gas-water combined backwashing, the gas pressure is 0.2-0.3 MPa, and the water flow rate is 0.4-0.6 m 3 / h, backwash time is 30-45 seconds.

[0017] Compared with the prior art, the present invention provides a concentration and filtration process for electroplating wastewater membrane separation, which has the following beneficial effects:

[0018] The concentration and filtration process for membrane separation of electroplating wastewater effectively avoids the use of coagulants, coagulant aids and flocculation steps through multi-stage fine physical filtration and membrane separation technology, reduces the use of chemical agents, and reduces the generation of chemical sludge. At the same time, it can also efficiently purify and concentrate electroplating wastewater to achieve the purpose of water resource reuse and heavy metal recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0020] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0021] Embodiment 1:

[0022] like Figure 1 As shown, a concentration and filtration process for electroplating wastewater membrane separation includes the following steps:

[0023] S1: Channel classification processing, install high-precision cameras and sensor arrays to monitor the size, shape, color of suspended solid particles in electroplating wastewater and the characteristic spectra of heavy metal ions and organic matter in real time, quickly analyze the collected data, accurately classify the electroplating wastewater into sub-flows with different pollution levels and components, and discharge them into different channels for treatment according to the classification;

[0024] The wastewater streams mainly composed of copper, nickel and zinc are distinguished according to the particle size and glossiness of the metal particles in the electroplating wastewater; the wastewater areas containing high concentrations of organic matter are identified according to the fluorescence characteristic spectrum of organic matter, and customized pre-filtration paths are designed for different diversions of wastewater. For wastewater with high content of large-particle metal impurities, it is guided into the magnetic separation channel. A high-strength permanent magnet array is set in this channel. The magnetic difference of metal particles is used to efficiently adsorb and separate magnetic metal particles such as iron, cobalt and nickel; for electroplating wastewater containing high concentrations of organic matter and tiny suspended impurities, it is made to enter the multi-layer gradient microporous filtration unit, which is composed of stainless steel sintered microporous filter materials with pore sizes of 50μm to 5μm arranged in sequence, with a flow rate of 0.2-0.3m 3 / h, used to gradually intercept impurities of different sizes;

[0025] S2: Unified filtration treatment, the electroplating wastewater after being treated in different channels is collected uniformly. The wastewater first enters the sand filter tank, which is filled with quartz sand of different particle sizes. The wastewater is 0.3-0.5m 3 / h passes through the sand filter to intercept sand, dust and metal debris in electroplating wastewater;

[0026] The particle size of the quartz sand in the sand filter gradually increases from top to bottom. The particle size of the top layer of fine sand is 0.4-0.6mm, the particle size of the middle layer of sand is 0.8-1.2mm, and the particle size of the bottom layer of coarse sand is 2-3mm. The sand filter is backwashed regularly with a backwashing intensity of 12-15L / (m 2 ·s), the backwash time is 5-8 minutes, which is used to remove impurities accumulated in the sand layer;

[0027] After sand filtration, the electroplating wastewater enters the activated carbon filter. The activated carbon uses granular coconut shell activated carbon to adsorb organic matter, residual chlorine and other impurities in the electroplating wastewater. The empty bed contact time of the activated carbon filter is controlled at 15-20 minutes. The electroplating wastewater slowly penetrates the activated carbon layer and removes some organic pollutants through adsorption.

[0028] The electroplating wastewater from the activated carbon filter enters the microfiltration system. The microfiltration membrane uses an inorganic ceramic membrane with a pore size of 0.1-0.2μm to remove the remaining tiny particles, bacteria and other impurities in the electroplating wastewater. The microfiltration system uses a dead-end filtration method with an operating pressure of 0.1-0.15MPa. The wastewater flow is controlled by a constant flow pump with a flow rate of 0.8-1.2m 3 / h;

[0029] During the filtration process of the microfiltration system, when the transmembrane pressure difference reaches 0.08-0.1MPa, the microfiltration membrane is backwashed. The backwashing adopts the combined backwashing of air and water. The gas pressure is 0.2-0.3MPa and the water flow rate is 0.4-0.6m 3 / h, backwash time is 30-45 seconds;

[0030] S3: Ultrafiltration membrane treatment. The ultrafiltration membrane uses a hollow fiber ultrafiltration membrane made of hydrophilic polyethersulfone. The ultrafiltration system adopts a cross-flow filtration method with a cross-flow velocity of 1.5-2m / s. The cross-flow velocity is maintained by a circulating pump to form a shear force on the membrane surface to reduce the deposition of pollutants on the membrane surface. The operating pressure is controlled at 0.18-0.22MPa, and the operating temperature is maintained at 20-25℃. A heat exchanger is set in the water inlet pipe to adjust the temperature of the electroplating wastewater. During operation, backwashing is performed every 45-60 minutes. Pure water is used for backwashing. The backwashing pressure is 0.1-0.12MPa and the backwashing time is 40-60 seconds to remove pollutants on the membrane surface. The permeate enters the next stage of reverse osmosis membrane treatment, and the concentrate returns to the microfiltration system for further treatment.

[0031] S4: Reverse osmosis membrane treatment. The reverse osmosis membrane adopts a rolled reverse osmosis membrane made of composite polyamide. The first-stage reverse osmosis operating pressure is controlled at 1.8-2.0MPa, the second-stage operating pressure is controlled at 1.0-1.2MPa, and the operating temperature is maintained at 22-24°C. During operation, chemical cleaning is performed every 1.5-2 hours to remove dirt and scaling substances on the membrane surface. After the electroplating wastewater is treated with the reverse osmosis membrane, fresh water and concentrate are finally produced.

[0032] Embodiment 2:

[0033] Cleaning of ultrafiltration membrane and reverse osmosis membrane: When the transmembrane pressure difference of the ultrafiltration membrane rises to 1.4-1.6 times of the initial value and the membrane flux drops to 75%-80% of the initial value, chemical cleaning is required. When cleaning, first stop the ultrafiltration system, drain the wastewater in the membrane assembly, and then use pure water at 0.8-1m 3 / h flow rate to flush the membrane surface for 10-12 minutes, then use 0.5%-0.6% nitric acid solution at a temperature of 28-32°C and a flow rate of 0.4-0.6m 3 / h flow rate for 40-50 minutes to remove inorganic dirt on the membrane surface, then rinse with pure water until neutral, and then use 0.3%-0.4% sodium hydroxide solution at a temperature of 30-33°C and a flow rate of 0.4-0.6m 3 / h flow rate for 40-50 minutes to remove organic dirt on the membrane surface, and finally rinse thoroughly with pure water;

[0034] When the normalized flux of the reverse osmosis membrane drops below 70% of the initial value and the pressure difference between the sections rises to more than 1.4 times the initial value, chemical cleaning is performed. First, the reverse osmosis system is shut down, and the membrane components are low-pressure flushed with fresh water for 12-15 minutes. Then, a 0.2%-0.3% disodium ethylenediaminetetraacetic acid (EDTA) solution is used at a temperature of 32-35°C and a pressure of 1-1.2 m 3 / h flow rate for 60-70 minutes to remove metal oxides and scale on the membrane surface, then rinse with fresh water for 10-12 minutes, and then use 2%-2.2% citric acid solution at a temperature of 30-33℃ and a flow rate of 1-1.2m 3 / h flow rate for 60-70 minutes to remove inorganic scale on the membrane surface, and finally rinse thoroughly with fresh water until the pH value and conductivity of the rinse water meet the requirements;

[0035] Integrity test of ultrafiltration membrane and reverse osmosis membrane: The integrity of ultrafiltration membrane assembly is tested by gas diffusion method every two weeks. The water inlet and water outlet of the membrane assembly are sealed, and nitrogen is injected into the concentrated water outlet to make the pressure reach 0.08-0.1MPa. Then the water outlet is tested for gas leakage. If gas leakage is detected, it indicates that the membrane assembly may be damaged. By injecting fluorescent tracer into the membrane assembly and detecting whether there is fluorescent signal at the water outlet with fluorescence detection equipment, the damaged position is determined, and then the membrane filaments are repaired or the membrane assembly is replaced;

[0036] The reverse osmosis membrane assembly is tested for integrity every day using the pressure maintenance method. Fill the membrane assembly with water, slowly increase the pressure to 80% of the operating pressure (1.44-1.6MPa), close the water inlet valve, and observe the pressure drop. If the pressure drops by more than 0.05-0.08MPa within 10-15 minutes, it indicates that the membrane assembly may be defective. Defective membrane assemblies can be repaired or replaced.

[0037] The performance of this process is compared with that of the existing process, wherein this process is recorded as an embodiment and the existing processes are recorded as comparative examples 1 and 2. The following is a comparison table:

[0038]

[0039] It can be seen that the process performance of the present invention is relatively excellent.

[0040] This process uses multi-stage fine physical filtration and membrane separation technology to effectively avoid the use of coagulants, coagulant aids and flocculation steps, reduce the use of chemical agents, and reduce the generation of chemical sludge. At the same time, it can also efficiently purify and concentrate electroplating wastewater to achieve the purpose of water resource reuse and heavy metal recovery.

[0041] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A concentration and filtration process for electroplating wastewater membrane separation, characterized in that: The steps include: S1: Channel classification processing, install high-precision cameras and sensor arrays to monitor the size, shape, color of suspended solid particles in electroplating wastewater and the characteristic spectra of heavy metal ions and organic matter in real time, quickly analyze the collected data, accurately classify the electroplating wastewater into sub-flows with different pollution levels and components, and discharge them into different channels for treatment according to the classification; S2: Unified filtration treatment, the electroplating wastewater after being treated in different channels is collected uniformly. The wastewater first enters the sand filter tank, which is filled with quartz sand of different particle sizes. The wastewater is 0.3-0.5m 3 / h passes through the sand filter to intercept sand, dust and metal debris in electroplating wastewater; After sand filtration, the electroplating wastewater enters the activated carbon filter. The activated carbon uses granular coconut shell activated carbon to adsorb organic matter, residual chlorine and other impurities in the electroplating wastewater. The empty bed contact time of the activated carbon filter is controlled at 15-20 minutes. The electroplating wastewater slowly penetrates the activated carbon layer and removes some organic pollutants through adsorption. The electroplating wastewater from the activated carbon filter enters the microfiltration system. The microfiltration membrane uses an inorganic ceramic membrane with a pore size of 0.1-0.2μm to remove the remaining tiny particles, bacteria and other impurities in the electroplating wastewater. The microfiltration system uses a dead-end filtration method with an operating pressure of 0.1-0.15MPa. The wastewater flow is controlled by a constant flow pump with a flow rate of 0.8-1.2m 3 / h; S3: Ultrafiltration membrane treatment. The ultrafiltration membrane uses a hollow fiber ultrafiltration membrane made of hydrophilic polyethersulfone. The ultrafiltration system adopts a cross-flow filtration method with a cross-flow velocity of 1.5-2m / s. The cross-flow velocity is maintained by a circulating pump to form a shear force on the membrane surface to reduce the deposition of pollutants on the membrane surface. The operating pressure is controlled at 0.18-0.22MPa, and the operating temperature is maintained at 20-25℃. A heat exchanger is set in the water inlet pipe to adjust the temperature of the electroplating wastewater. During operation, backwashing is performed every 45-60 minutes. Pure water is used for backwashing. The backwashing pressure is 0.1-0.12MPa and the backwashing time is 40-60 seconds to remove pollutants on the membrane surface. The permeate enters the next stage of reverse osmosis membrane treatment, and the concentrate returns to the microfiltration system for further treatment. S4: Reverse osmosis membrane treatment. The reverse osmosis membrane adopts a rolled reverse osmosis membrane made of composite polyamide. The first-stage reverse osmosis operating pressure is controlled at 1.8-2.0MPa, the second-stage operating pressure is controlled at 1.0-1.2MPa, and the operating temperature is maintained at 22-24°C. During operation, chemical cleaning is performed every 1.5-2 hours to remove dirt and scaling substances on the membrane surface. After the electroplating wastewater is treated with the reverse osmosis membrane, fresh water and concentrate are finally produced.

2. A concentration and filtration process for electroplating wastewater membrane separation according to claim 1, characterized in that: In S1, wastewater streams mainly containing copper, nickel and zinc are distinguished according to the particle size and glossiness of metal particles in electroplating wastewater; wastewater areas containing high concentrations of organic matter are identified according to the fluorescent characteristic spectrum of organic matter, and customized pre-filtration paths are designed for wastewater with different diversions. For wastewater with high content of large-particle metal impurities, wastewater is guided to enter a magnetic separation channel, in which a high-strength permanent magnet array is arranged, and magnetic metal particles such as iron, cobalt and nickel are efficiently adsorbed and separated by utilizing the magnetic difference of metal particles; For electroplating wastewater containing high concentrations of organic matter and tiny suspended impurities, it enters a multi-layer gradient microporous filtration unit, which is composed of stainless steel sintered microporous filter materials with pore sizes of 50μm to 5μm arranged in sequence, with a flow rate of 0.2-0.3m 3 / h, used to gradually intercept impurities of different sizes.

3. A concentration and filtration process for electroplating wastewater membrane separation according to claim 1, characterized in that: In the S2, the particle size of the quartz sand in the sand filter gradually increases from top to bottom, the particle size of the top layer fine sand is 0.4-0.6mm, the particle size of the middle layer sand is 0.8-1.2mm, and the particle size of the bottom layer coarse sand is 2-3mm. The sand filter is backwashed regularly, and the backwashing intensity is 12-15L / (m 2 ·s), and the backwash time is 5-8 minutes to remove impurities accumulated in the sand layer.

4. A concentration and filtration process for electroplating wastewater membrane separation according to claim 1, characterized in that: In S2, during the filtration process, when the transmembrane pressure difference reaches 0.08-0.1MPa, the microfiltration membrane is backwashed. The backwashing adopts gas-water combined backwashing. The gas pressure is 0.2-0.3MPa and the water flow rate is 0.4-0.6m 3 / h, backwash time is 30-45 seconds.

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