Electroplating wastewater membrane separation concentration filter process

Abstract

This invention discloses a concentration and filtration process for membrane separation of electroplating wastewater. This invention relates to the field of electroplating wastewater treatment. S1: Channel classification treatment, installing a high-precision camera and sensor array to monitor in real time the size, shape, and color of suspended solid particles in the electroplating wastewater, as well as the characteristic spectra of heavy metal ions and organic matter. The collected data is rapidly analyzed to accurately classify the electroplating wastewater into sub-streams with different levels of pollution and components, and these sub-streams are then discharged into different channels for treatment according to their classification. S2: Unified filtration treatment; S3: Ultrafiltration membrane treatment; S4: Reverse osmosis membrane treatment. This invention's concentration and filtration process for membrane separation of electroplating wastewater effectively reduces the use of chemical agents and the generation of chemical sludge through multi-stage fine physical filtration and membrane separation technology. It also efficiently purifies and concentrates electroplating wastewater, achieving the goals of water resource reuse and heavy metal recovery.

Description

Technical Field

[0001] This invention relates to the field of electroplating wastewater treatment, and particularly to a concentration filtration process for membrane separation of electroplating wastewater. Background Technology

[0002] Electroplating wastewater refers to various types of wastewater generated during the electroplating production process. It mainly originates from the cleaning of plated parts, filtration of plating solutions, and leakage from plating tanks. Its composition is quite complex, usually containing a large number of heavy metal ions, such as chromium, nickel, copper, zinc, and cadmium. 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 and digestive systems, and long-term exposure may cause cancer; nickel ions may cause skin allergies and respiratory diseases; acidic and alkaline wastewater can change the pH value of water bodies, destroy the living environment of aquatic organisms, and affect the self-purification capacity of water bodies; cyanide is highly toxic, and even a small amount can cause fatal damage to organisms.

[0003] Electroplating wastewater treatment typically involves steps such as coagulation, flocculant application, and flocculation, which generates chemical sludge, increasing overall costs and causing significant subsequent pollution.

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

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

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

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

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

[0009] S2: Unified filtration treatment, collecting electroplating wastewater after treatment through different channels. The wastewater first enters a sand filter tank filled with quartz sand of different particle sizes, with the wastewater flowing at a concentration of 0.3-0.5 m³. 3 / h passes through a sand filter to intercept sand and metal debris in electroplating wastewater;

[0010] After passing through sand filtration, the electroplating wastewater enters the activated carbon filter. The activated carbon used is granular coconut shell activated carbon, which is used 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 permeates in the activated carbon layer and removes some organic pollutants through adsorption.

[0011] Electroplating wastewater from the activated carbon filter enters the microfiltration system. The microfiltration membrane is an inorganic ceramic membrane with a pore size of 0.1-0.2 μm, used to remove remaining microparticles, bacteria, and other impurities from the electroplating wastewater. The microfiltration system employs dead-end filtration, operating at a pressure of 0.1-0.15 MPa. The wastewater flow rate is controlled by a constant flow pump, ranging from 0.8-1.2 m³ / h. 3 / h;

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

[0013] S4: Reverse osmosis membrane treatment. The reverse osmosis membrane is a spiral wound reverse osmosis membrane made of composite polyamide material. The first stage reverse osmosis operating pressure is controlled at 1.8-2.0 MPa, the second stage operating pressure is controlled at 1.0-1.2 MPa, and the operating temperature is maintained at 22-24℃. During operation, chemical cleaning is performed every 1.5-2 hours to remove dirt and scale from the membrane surface. After the electroplating wastewater is treated by the reverse osmosis membrane, it finally produces fresh water and concentrate.

[0014] Preferably, in step S1, wastewater streams dominated by different metals (copper, nickel, and zinc) are distinguished based on the particle size and gloss of the metal particles in the electroplating wastewater; wastewater areas containing high concentrations of organic matter are identified based on the fluorescence characteristic spectrum of organic matter; and customized pre-filtration paths are designed for different wastewater streams. For wastewater with high content of large-particle metal impurities, it is guided into a magnetic separation channel. This channel is equipped with a high-intensity permanent magnet array, which utilizes the magnetic differences of metal particles 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 directed to a multi-layer gradient microporous filtration unit. This unit consists of stainless steel sintered microporous filter media with pore sizes ranging from 50μm to 5μm arranged sequentially, with a flow rate of 0.2-0.3m / s. 3 / h is used to progressively intercept impurities of different sizes.

[0015] Preferably, in step S2, the particle size of the quartz sand in the sand filter gradually increases from top to bottom. The finest sand in the uppermost layer has a particle size of 0.4-0.6 mm, the middle layer has a particle size of 0.8-1.2 mm, and the coarse sand in the lower layer has a particle size of 2-3 mm. The sand filter is backwashed periodically, with a backwashing intensity of 12-15 L / (m²). 2 ·s), the backwashing time is 5-8 minutes, used to remove impurities accumulated in the sand layer.

[0016] Preferably, in step S2, during the filtration process, when the transmembrane pressure difference reaches 0.08-0.1 MPa, the microfiltration membrane is backwashed. The backwashing employs a combined air-water backwash, with a gas pressure of 0.2-0.3 MPa and a water flow rate of 0.4-0.6 m³ / h. 3 / h, backwash time is 30-45 seconds.

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

[0018] This electroplating wastewater membrane separation and concentration filtration process effectively avoids the use of coagulants, coagulant aids, and flocculation steps through multi-stage fine physical filtration and membrane separation technology, reducing the use of chemical agents and the generation of chemical sludge. At the same time, it can efficiently purify and concentrate electroplating wastewater, achieving the purpose of water resource reuse and heavy metal recovery. Attached Figure Description

[0019] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0020] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0021] Example 1:

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

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

[0024] Wastewater streams primarily composed of copper, nickel, and zinc are differentiated based on the particle size and gloss of the metal particles in the electroplating wastewater. Wastewater regions containing high concentrations of organic matter are identified using the fluorescence spectral characteristics of organic matter. Customized pre-filtration paths are designed for different wastewater streams. For wastewater with high levels of large-particle metal impurities, it is guided into a magnetic separation channel. This channel contains a high-intensity permanent magnet array, utilizing the magnetic differences of metal particles 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 enters a multi-layer gradient microporous filtration unit. This unit consists of sintered stainless steel microporous filter media with pore sizes ranging from 5μm to 5μm arranged sequentially, with a flow rate of 0.2-0.3m / s. 3 / h is used to progressively intercept impurities of different sizes;

[0025] S2: Unified filtration treatment, collecting electroplating wastewater after treatment through different channels. The wastewater first enters a sand filter tank filled with quartz sand of different particle sizes, with the wastewater flowing at a concentration of 0.3-0.5 m³. 3 / h passes through a sand filter to intercept sand and metal debris in electroplating wastewater;

[0026] In the sand filter, the particle size of the quartz sand gradually increases from top to bottom. The finest sand in the top layer has a particle size of 0.4-0.6 mm, the middle layer has a particle size of 0.8-1.2 mm, and the coarse sand in the bottom layer has a particle size of 2-3 mm. The sand filter is backwashed regularly at an intensity of 12-15 L / (m²). 2 ·s), the backwashing time is 5-8 minutes, used to remove impurities accumulated in the sand layer;

[0027] After passing through sand filtration, the electroplating wastewater enters the activated carbon filter. The activated carbon used is granular coconut shell activated carbon, which is used 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 permeates in the activated carbon layer and removes some organic pollutants through adsorption.

[0028] Electroplating wastewater from the activated carbon filter enters the microfiltration system. The microfiltration membrane is an inorganic ceramic membrane with a pore size of 0.1-0.2 μm, used to remove remaining microparticles, bacteria, and other impurities from the electroplating wastewater. The microfiltration system employs dead-end filtration, operating at a pressure of 0.1-0.15 MPa. The wastewater flow rate is controlled by a constant flow pump, ranging from 0.8-1.2 m³ / h. 3 / h;

[0029] During the filtration process, when the transmembrane pressure difference reaches 0.08-0.1 MPa, the microfiltration membrane is backwashed. Backwashing employs a combined air-water backwash, with a gas pressure of 0.2-0.3 MPa and a water flow rate of 0.4-0.6 m³ / h. 3 / h, backwash time 30-45 seconds;

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

[0031] S4: Reverse osmosis membrane treatment. The reverse osmosis membrane is a spiral wound reverse osmosis membrane made of composite polyamide material. The first stage reverse osmosis operating pressure is controlled at 1.8-2.0 MPa, the second stage operating pressure is controlled at 1.0-1.2 MPa, and the operating temperature is maintained at 22-24℃. During operation, chemical cleaning is performed every 1.5-2 hours to remove dirt and scale from the membrane surface. After the electroplating wastewater is treated by the reverse osmosis membrane, it finally produces fresh water and concentrate.

[0032] Example 2:

[0033] Cleaning of ultrafiltration and reverse osmosis membranes: When the transmembrane pressure difference of the ultrafiltration membrane rises to 1.4-1.6 times its initial value and the membrane flux drops to 75%-80% of its initial value, chemical cleaning is required. During cleaning, first stop the ultrafiltration system, drain the wastewater from the membrane module, and then rinse with pure water at a flow rate of 0.8-1 m³ / h. 3 Rinse the membrane surface at a flow rate of / h for 10-12 minutes, then use a 0.5%-0.6% nitric acid solution at a temperature of 28-32℃ with a flow rate of 0.4-0.6m. 3Circulate the membrane at a flow rate of / h for 40-50 minutes to remove inorganic fouling. Then rinse with pure water until neutral. Finally, use a 0.3%-0.4% sodium hydroxide solution at 30-33℃ with a flow rate of 0.4-0.6m. 3 The membrane is circulated and cleaned for 40-50 minutes at a flow rate of / h to remove organic dirt from the membrane surface. Finally, it is thoroughly rinsed with pure water.

[0034] When the standardized flux of the reverse osmosis membrane drops below 70% of its initial value and the inter-stage pressure difference rises to more than 1.4 times its initial value, chemical cleaning is performed. First, the reverse osmosis system is shut down, and the membrane modules are low-pressure flushed with fresh water for 12-15 minutes. Then, a 0.2%-0.3% disodium ethylenediaminetetraacetate (EDTA) solution is used at a temperature of 32-35°C, with a flow rate of 1-1.2 m... 3 Circulate the membrane at a flow rate of / h for 60-70 minutes to remove metal oxides and scale from the membrane surface. Then rinse with fresh water for 10-12 minutes, followed by rinsing with a 2%-2.2% citric acid solution at 30-33℃ at a flow rate of 1-1.2m. 3 The membrane is circulated and cleaned at a flow rate of / h for 60-70 minutes to remove inorganic scale from the membrane surface. Finally, it is rinsed thoroughly with fresh water until the pH and conductivity of the rinse water meet the requirements.

[0035] Integrity testing of ultrafiltration and reverse osmosis membranes: The integrity of the ultrafiltration membrane module is tested every two weeks using the gas diffusion method. The inlet and outlet of the membrane module are sealed, and nitrogen is injected into the concentrate outlet to bring the pressure to 0.08-0.1 MPa. Then, gas leakage is checked at the outlet. If gas leakage is detected, it indicates that the membrane module may be damaged. By injecting a fluorescent tracer into the membrane module, fluorescent detection equipment is used at the outlet to detect whether there is a fluorescent signal to determine the location of the damage. Subsequently, the membrane fibers are repaired or the membrane module is replaced.

[0036] The integrity of the reverse osmosis membrane module is tested daily using the pressure holding method. The membrane module is filled with water, and the pressure is slowly increased to 80% of the operating pressure (1.44-1.6 MPa). The inlet valve is then closed, and the pressure drop is observed. If the pressure drops by more than 0.05-0.08 MPa within 10-15 minutes, it indicates that the membrane module may have a defect. Defective membrane modules can be repaired or replaced.

[0037] The performance of this process and existing processes are compared. This process is referred to as the example, and the existing processes are referred to as Comparative Examples 1 and 2. The comparison table is as follows:

[0038]

[0039] Therefore, it can be seen that the process performance of the present invention is excellent.

[0040] This process effectively avoids the use of coagulants, flocculants, and flocculation steps through multi-stage fine physical filtration and membrane separation technology, reducing the use of chemical agents and the generation of chemical sludge. At the same time, it can efficiently purify and concentrate electroplating wastewater, achieving the goals of water resource reuse and heavy metal recovery.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A concentration and filtration process for membrane separation of electroplating wastewater, characterized in that: The process includes the following steps: S1: Channel classification and treatment. High-precision cameras and sensor arrays are installed to monitor in real time the size, shape, and color of suspended solid particles in the electroplating wastewater, as well as the characteristic spectra of heavy metal ions and organic matter. The collected data is quickly analyzed to accurately classify the electroplating wastewater into sub-streams with different levels of pollution and components, and then discharge them into different channels for treatment according to the classification; S2: Unified filtration treatment. The electroplating wastewater after treatment in different channels is collected uniformly. The wastewater first enters a sand filter tank, which is filled with quartz sand of different particle sizes. The wastewater is filtered at a concentration of 0.3-0.5 m³. 3 The wastewater passes through a sand filter to intercept sand and metal debris. After sand filtration, the wastewater enters an activated carbon filter. Granular coconut shell activated carbon is used to adsorb organic matter, residual chlorine, and other impurities from the wastewater. The empty bed contact time of the activated carbon filter is controlled at 15-20 minutes, allowing the wastewater to slowly permeate through the activated carbon layer, removing some organic pollutants through adsorption. The wastewater exiting the activated carbon filter then enters a microfiltration system. The microfiltration membrane is an inorganic ceramic membrane with a pore size of 0.1-0.2 μm, used to remove remaining small particles, bacteria, and other impurities from the wastewater. The microfiltration system uses dead-end filtration, operating at a pressure of 0.1-0.15 MPa, and the wastewater flow rate is controlled by a constant flow pump at 0.8-1.2 m³ / h. 3 / h; S3: Ultrafiltration membrane treatment. The ultrafiltration membrane is a hollow fiber ultrafiltration membrane made of hydrophilic polyethersulfone. The ultrafiltration system adopts cross-flow filtration with a cross-flow velocity of 1.5-2 m / s. The cross-flow velocity is maintained by a circulating pump, which creates shear force on the membrane surface to reduce the deposition of pollutants. The operating pressure is controlled at 0.18-0.22 MPa, and the operating temperature is maintained at 20-25℃. A heat exchanger is installed in the inlet pipe to regulate the temperature of the electroplating wastewater. During operation, backwashing is performed every 45-60 minutes. Pure water is used for backwashing, with a backwash pressure of 0.1-0.12 MPa and a backwash time of 40-60 seconds to remove pollutants from the membrane surface. The permeate enters the next stage of reverse osmosis membrane treatment, and the concentrate is returned to the microfiltration system for further treatment. S4: Reverse osmosis membrane treatment. The reverse osmosis membrane is a spiral wound reverse osmosis membrane made of composite polyamide material. 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℃. During operation, chemical cleaning is performed every 1.5-2 hours to remove dirt and scale from the membrane surface. After the electroplating wastewater is treated by the reverse osmosis membrane, it finally produces fresh water and concentrate. In S1, wastewater streams dominated by different metals, such as copper, nickel, and zinc, are distinguished based on the particle size and gloss of the metal particles in the electroplating wastewater; wastewater areas containing high concentrations of organic matter are identified based on the fluorescence characteristic spectrum of organic matter; customized pre-filtration paths are designed for different wastewater streams; and for wastewater with high content of large-particle metal impurities, it is guided into a magnetic separation channel. A high-intensity permanent magnet array is set in this channel to efficiently adsorb and separate magnetic metal particles such as iron, cobalt, and nickel by utilizing the magnetic differences of metal particles. For electroplating wastewater containing high concentrations of organic matter and minute suspended impurities, it is introduced into a multi-layer gradient microporous filtration unit. This unit consists of sintered stainless steel microporous filter media with pore sizes ranging from 50μm to 5μm arranged sequentially, with a flow rate of 0.2-0.3m / s. 3 / h is used to progressively intercept impurities of different sizes; In S2, the particle size of the quartz sand in the sand filter gradually increases from top to bottom. The finest sand in the uppermost layer has a particle size of 0.4-0.6 mm, the middle layer has a particle size of 0.8-1.2 mm, and the coarse sand in the lower layer has a particle size of 2-3 mm. The sand filter is backwashed periodically at an intensity of 12-15 L / (m²). 2 ·s), the backwashing time is 5-8 minutes, used to remove impurities accumulated in the sand layer; In step S2, during the filtration process, when the transmembrane pressure difference reaches 0.08-0.1 MPa, the microfiltration membrane is backwashed. The backwashing employs a combined air-water backwash, with a gas pressure of 0.2-0.3 MPa and a water flow rate of 0.4-0.6 m³ / h. 3 / h, backwash time is 30-45 seconds.

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