Zero-discharge process for membrane separation of electroplating wastewater

Abstract

The invention discloses a zero discharge process for electroplating wastewater membrane separation, and relates to the field of wastewater discharge, and the zero discharge process comprises the following operation steps: S1, setting up discharge equipment; s2, carrying out micro-electrolysis reaction; s3, advanced oxidation reaction; s4, filtering treatment; s5, membrane treatment: the pretreated electroplating wastewater enters a first-stage RO device, effluent of the first-stage RO device enters a second-stage RO device, salt and organic matter solution intercepted by a first-stage RO membrane is discharged as concentrated water of the membrane, enters a concentrated water RO membrane device and is further filtered in the concentrated water RO membrane device, effluent of the concentrated water RO membrane is recycled, and concentrated water enters the concentrated water RO membrane device and is filtered again; and S6, carrying out evaporation treatment. According to the zero-discharge process for electroplating wastewater membrane separation, when electroplating wastewater is discharged, the dosage of chemicals such as coagulant can be reduced, organic matters in water can be removed by utilizing a chemical oxidation method, and meanwhile, the method is high in water recovery rate, stable in water quality and small in concentrated water generation amount.

Description

Technical Field

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

[0002] Electroplating wastewater has a complex composition, high organic concentration, poor biodegradability, and high salt content, producing nickel-containing wastewater, copper-containing wastewater, pre-treatment wastewater, etc. In the existing technology, the treatment and reuse process of electroplating wastewater mostly uses coagulation and sedimentation to remove metal ions and biochemical processes to remove organic matter.

[0003] At the same time, after pretreatment, most of the organic matter and heavy metals in the wastewater are removed, but pretreatment cannot remove the salt in the wastewater, nor can it completely remove the organic matter in the wastewater. The pretreated wastewater will enter the reuse treatment unit to remove all the salt and organic matter in the wastewater to meet the standards for reuse production. In the prior art, the treatment and reuse process of electroplating wastewater mostly uses RO membrane filtration process and evaporation process to remove salt and organic matter. The commonly used process is as follows: wastewater → coagulation sedimentation → anaerobic aerobic biological treatment → primary RO membrane → secondary RO membrane → reuse; the primary RO membrane will intercept the organic matter and salt in the wastewater to form concentrated water, which needs to be filtered or evaporated again before it can be reused. The commonly used process is as follows: primary RO membrane concentrated water → DTRO → reuse → DTRO concentrated water → evaporation → reuse; coagulation sedimentation requires the addition of a large amount of reagents, which produces a large amount of sludge.

[0004] Electroplating wastewater has poor biodegradability, and temperature, pH, salt, etc. have a great impact on the anaerobic and aerobic biological treatment process, which can easily cause unstable operation, low organic matter removal rate, large floor space, and inability to operate automatically; due to the high organic matter concentration and high salt content in the wastewater, the first-stage RO is prone to blockage, resulting in the need for frequent cleaning, making the treated water volume unstable and the work efficiency poor; the existing technology produces a large amount of concentrated water, but a small amount of water, and the required evaporation device has a large processing capacity, high energy consumption, and high operating costs; the use of a first-stage RO membrane cannot stably meet the reuse requirements, and the use of a two-stage RO will produce a large amount of concentrated water.

[0005] The primary RO membrane produces a large amount of concentrated water, which accounts for about 30% of the water intake of the primary RO membrane. The concentrated water of the primary RO membrane is filtered and concentrated again by DTRO. The investment of DTRO membrane is relatively high, about 25,000-35,000 yuan / ton of wastewater / day.

[0006] DTRO, also known as disc-tube reverse osmosis, is a membrane column composed of a disc-type membrane, a guide plate, an O-type rubber gasket, a central tie rod and a pressure-resistant casing. DTRO is mainly used for leachate treatment. It has good pollution resistance to high-concentration organic matter, a small amount of particulate matter and salt in wastewater. However, the structure of DTRO determines that the unit water output and cost of DTRO are relatively high. The operating cost of DTRO membrane equipment is relatively high. The operating cost of treating 1 ton of water is about 40-45 yuan / ton of wastewater. The existing technology produces a large amount of concentrated water, and the evaporation device required has a large processing capacity. The energy consumption required to evaporate the concentrated water is high, and the evaporation operating cost is high.

[0007] Therefore, it is necessary to propose a zero-emission process for electroplating wastewater membrane separation to solve the above problems. Summary of the invention

[0008] The main purpose of the present invention is to provide a zero-emission process for membrane separation of electroplating wastewater, which can effectively solve the problems in the background technology.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A zero-discharge process for membrane separation of electroplating wastewater, comprising the following steps:

[0011] S1: Build discharge equipment, including a water collection tank, a pretreatment unit, a lifting pump, a micro-electrolysis reactor, an aeration mixing device, a water pool, a quartz sand filter, an activated carbon filter, an ultrafiltration device, a primary RO device, a secondary RO device, a concentrated water RO membrane device, an evaporation device, and a circulation pump; the primary RO device, the secondary RO device, and the concentrated water RO membrane device are all equipped with a high-pressure pump, a membrane assembly, and a pressure control instrument;

[0012] S2: Micro-electrolysis reaction, the electroplating wastewater is discharged into the collection tank and passed through the pretreatment unit. The lifting pump transports the electroplating wastewater through the micro-electrolysis reactor. The micro-electrolysis reactor aerates and mixes the electroplating wastewater through the aeration mixing device. The wastewater enters the pool equipped with micro-electrolysis fillers under acidic conditions. The micro-electrolysis fillers undergo redox reactions under acidic conditions to produce highly oxidizing free radicals, which break down the macromolecular organic matter in the water into small molecular organic matter, which is used to efficiently remove COD, reduce chroma, and improve biodegradability;

[0013] S3: Advanced oxidation reaction. After the electroplating wastewater undergoes micro-electrolysis, it enters the advanced oxidation reaction. Hydrogen peroxide is added to the water pool for reaction. The two reagents, ferrous sulfate produced by the micro-electrolysis reaction and the added hydrogen peroxide, react under acidic pH conditions to generate highly oxidizing OH- ions, which are used to break the chemical chain of organic matter in the water, converting large organic matter into small molecular organic matter, and reducing the organic matter content of the wastewater.

[0014] S4: Filtration treatment: the effluent after the advanced oxidation reaction enters the quartz sand filtration, activated carbon filtration and ultrafiltration device in sequence to further remove impurities and colloids in the water, and then enters the membrane treatment process;

[0015] S5: Membrane treatment. The electroplating wastewater after pretreatment enters the primary RO device. The effluent of the primary RO device enters the secondary RO device. Organic matter and salt are removed in the primary RO device and the secondary RO device. The effluent of the secondary RO device is reused for production. The salt and organic solution intercepted by the primary RO membrane are discharged as concentrated water of the membrane and enter the concentrated water RO membrane device. It is further filtered in the concentrated water RO membrane device. The effluent of the concentrated water RO membrane is reused, and the concentrated water enters the concentrated water RO membrane device for filtration again. The produced water produced by the concentrated water RO device is used for reuse production, and the concentrated water enters the evaporation device for evaporation.

[0016] S6: Evaporation treatment: the solution in the evaporation device is heated to 100°C and circulated continuously in the evaporation chamber of the evaporation device through a circulation pump. The water in the wastewater evaporates and separates from the pollutants, the organic matter and salt form solids, and the water vapor is condensed into water for reuse.

[0017] Preferably, in S1, the pretreatment unit includes coagulation sedimentation, micro-electrolysis filler, Fenton chemical oxidation, sand filtration, carbon filtration, and ultrafiltration, which are used to remove organic matter, heavy metals, and particulate matter in electroplating wastewater.

[0018] Preferably, in S5, the primary RO device adopts Hyde Energy low-pressure anti-pollution reverse osmosis membrane, including one of PRO-XR1 and PROC30, with a filtration pressure of 1.5-3.0 MPA and a recovery rate of 70-75%; the secondary RO device adopts Hyde Energy low-pressure anti-pollution reverse osmosis membrane, with a filtration pressure of 1.5-1.8 MPA and a recovery rate of 75-80%; the concentrated water RO membrane adopts one of Hyde Energy medium-pressure and high-pressure anti-pollution reverse osmosis membranes, with a filtration pressure of 2.5-4.0 MPA and a recovery rate of 65-70%. The primary RO device, the secondary RO device, and the concentrated water RO membrane device are cleaned with hydrochloric acid and sodium hydroxide after being used for 1-2 years.

[0019] Preferably, in S6, the solution in the evaporation device is heated to 100°C using either electricity or steam.

[0020] Compared with the prior art, the present invention provides a zero-emission process for electroplating wastewater membrane separation, which has the following beneficial effects:

[0021] 1. The electroplating wastewater membrane separation uses a zero-emission process and replaces traditional coagulation and sedimentation with a micro-electrolysis process. The electroplating wastewater itself is mainly acidic. The iron-carbon filler in the micro-electrolysis process undergoes a micro-electrolysis reaction under the conditions of acidic wastewater to produce ferrous ions, which can be used as a coagulant. At the same time, the pH value of the wastewater will increase, which can reduce the addition of acid and coagulant.

[0022] 2. The zero-emission process of membrane separation of electroplating wastewater replaces the traditional biological treatment process with a micro-electrolysis process. The micro-electrolysis process will produce an oxidation reaction during the reaction, which can oxidize and decompose organic matter in the water and reduce the concentration of organic matter. At the same time, the micro-electrolysis process is not affected by ambient temperature, salinity, etc. It has stable operation, simple operation, and can be operated automatically.

[0023] 3. The zero-emission process for membrane separation of electroplating wastewater adopts a roll-to-roll RO membrane treatment process instead of a DTRO membrane treatment process. While achieving the same effluent quality, it can effectively reduce the amount of concentrated water that needs to be evaporated, reduce the cost of concentrated water treatment equipment, and reduce the operating cost of concentrated water treatment equipment.

[0024] 4. The electroplating wastewater membrane separation adopts zero emission technology, and the roll-type packaged RO membrane is used to filter and concentrate the concentrated water produced by the first-level RO. Finally, the concentrated water accounts for less than 10% of the total treated water volume. The amount of water that needs to be treated by the evaporation treatment process is greatly reduced, which reduces the operating cost and energy consumption of the whole system.

[0025] 5. The electroplating wastewater membrane separation uses a zero-emission process. Since membrane separation is a physical filtration method, it is less affected by external factors and has a very high retention rate for inorganic salts and most COD. Therefore, it can effectively ensure the water quality of the effluent. The membrane component has a design operating pressure of up to 60 bar, which can achieve high-fold concentration of the liquid to reduce the amount of concentrated liquid processed and reduce the investment cost and operating cost of subsequent processing equipment.

[0026] 6. The zero-emission process is used for membrane separation of electroplating wastewater. This method can reduce the addition of chemicals such as coagulants when discharging electroplating wastewater, and can use chemical oxidation methods to remove organic matter in the water, making the overall method more stable and simpler. At the same time, this method has a high water recovery rate, stable water quality, and a small amount of concentrated water. The overall equipment investment is 20-30% lower than the existing commonly used processes, and the operating costs are 20-30% lower than the existing commonly used processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0028] 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.

[0029] like Figure 1 As shown, a zero-discharge process for electroplating wastewater membrane separation includes the following steps:

[0030] S1: Build discharge equipment, including water collection tank, pretreatment unit, lifting pump, micro-electrolysis reactor, aeration mixing device, water pool, quartz sand filtration, activated carbon filtration, ultrafiltration device, primary RO device, secondary RO device, concentrated water RO membrane device, evaporation device, circulation pump; primary RO device, secondary RO device, concentrated water RO membrane device are all equipped with high-pressure pump, membrane assembly, pressure control instrument; pretreatment unit includes coagulation sedimentation, micro-electrolysis filler, Fenton chemical oxidation, sand filtration, carbon filtration, ultrafiltration, which are used to remove organic matter, heavy metals and particulate matter in electroplating wastewater;

[0031] S2: Micro-electrolysis reaction, the electroplating wastewater is discharged into the collection tank and passed through the pretreatment unit. The lifting pump transports the electroplating wastewater through the micro-electrolysis reactor. The micro-electrolysis reactor aerates and mixes the electroplating wastewater through the aeration mixing device. The wastewater enters the pool equipped with micro-electrolysis fillers under acidic conditions. The micro-electrolysis fillers undergo redox reactions under acidic conditions to produce highly oxidizing free radicals, which break down the macromolecular organic matter in the water into small molecular organic matter, which is used to efficiently remove COD, reduce chroma, and improve biodegradability;

[0032] S3: Advanced oxidation reaction. After the electroplating wastewater undergoes micro-electrolysis, it enters the advanced oxidation reaction. Hydrogen peroxide is added to the water pool for reaction. The two reagents, ferrous sulfate produced by the micro-electrolysis reaction and the added hydrogen peroxide, react under acidic pH conditions to generate highly oxidizing OH- ions, which are used to break the chemical chain of organic matter in the water, converting large organic matter into small molecular organic matter, and reducing the organic matter content of the wastewater.

[0033] S4: Filtration treatment: the effluent after the advanced oxidation reaction enters the quartz sand filtration, activated carbon filtration and ultrafiltration device in sequence to further remove impurities and colloids in the water, and then enters the membrane treatment process;

[0034] S5: Membrane treatment. The electroplating wastewater after pretreatment enters the primary RO device. The effluent of the primary RO device enters the secondary RO device. Organic matter and salt are removed in the primary RO device and the secondary RO device. The effluent of the secondary RO device is reused for production. The salt and organic solution intercepted by the primary RO membrane are discharged as concentrated water of the membrane and enter the concentrated water RO membrane device. It is further filtered in the concentrated water RO membrane device. The effluent of the concentrated water RO membrane is reused, and the concentrated water enters the concentrated water RO membrane device for filtration again. The produced water produced by the concentrated water RO device is used for reuse production, and the concentrated water enters the evaporation device for evaporation.

[0035] The primary RO device uses Hyde Energy's low-pressure anti-pollution reverse osmosis membrane, including one of PRO-XR1 and PROC30, with a filtration pressure of 1.5-3.0MPA and a recovery rate of 70-75%; the secondary RO device uses Hyde Energy's low-pressure anti-pollution reverse osmosis membrane, with a filtration pressure of 1.5-1.8MPA and a recovery rate of 75-80%; the concentrated water RO membrane uses Hyde Energy's medium-pressure and high-pressure anti-pollution reverse osmosis membranes, with a filtration pressure of 2.5-4.0MPA and a recovery rate of 65-70%. The primary RO device, the secondary RO device, and the concentrated water RO membrane device are cleaned with hydrochloric acid and sodium hydroxide after 1-2 years of use;

[0036] S6: Evaporation treatment: the solution in the evaporation device is heated to 100°C by either electricity or steam, and circulated continuously in the evaporation chamber of the evaporation device through a circulating pump. The water in the wastewater evaporates and separates from the pollutants, the organic matter and salt form solids, and the water vapor is condensed into water for reuse.

[0037] Based on the present invention, the prior art is compared, wherein the present invention is an embodiment and the prior art is a comparative example. The following is a comparison table:

[0038]

[0039] It can be seen that the process of the present invention has obvious advantages.

[0040] Micro-electrolysis technology is used to replace traditional coagulation and sedimentation. Electroplating wastewater itself is mainly acidic. The iron-carbon filler in the micro-electrolysis process undergoes micro-electrolysis reaction under the conditions of acidic wastewater to produce ferrous ions, which can be used as coagulants. At the same time, the pH value of the wastewater will increase, which can reduce the addition of acid and coagulants. The micro-electrolysis process replaces the traditional biological treatment process. The micro-electrolysis process will produce an oxidation reaction during the reaction, which can oxidize and decompose organic matter in the water and reduce the concentration of organic matter. At the same time, the micro-electrolysis process is not affected by ambient temperature, salinity, etc., and has stable operation, simple operation, and can be automatically operated. The roll-type encapsulated RO membrane treatment process is used to replace the DTRO membrane treatment process. Under the condition of achieving the same effluent water quality, it can effectively reduce the amount of concentrated water that needs to be evaporated, reduce the cost of concentrated water treatment equipment, and reduce the operating cost of concentrated water treatment equipment; the roll-type encapsulated RO membrane used is used to process the concentrated water produced by the first-level RO. After filtration and concentration, the final concentrated water accounts for less than 10% of the total treated water volume. The amount of water that needs to be treated by the evaporation treatment process is greatly reduced, reducing the operating cost and energy consumption of the entire system; since membrane separation is a physical filtration method, it is less affected by external factors and has a very high retention rate for inorganic salts and most COD, so it can effectively guarantee the water quality of the effluent. The design operating pressure of the membrane component is up to 60bar, which can achieve high-fold concentration of the liquid to reduce the amount of concentrated liquid treated and reduce the investment cost and operating cost of subsequent treatment equipment; this method can reduce the addition of chemicals such as coagulants when discharging electroplating wastewater, and can use chemical oxidation methods to remove organic matter in the water, making the overall method more stable and simpler. At the same time, this method has a high water recovery rate, stable water quality, and a small amount of concentrated water. The overall equipment investment is 20-30% lower than the existing commonly used processes, and the operating cost is 20-30% lower than the existing commonly used processes.

[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 zero-discharge process for membrane separation of electroplating wastewater, characterized in that: The steps include: S1: Build discharge equipment, including a water collection tank, a pretreatment unit, a lifting pump, a micro-electrolysis reactor, an aeration mixing device, a water pool, a quartz sand filter, an activated carbon filter, an ultrafiltration device, a primary RO device, a secondary RO device, a concentrated water RO membrane device, an evaporation device, and a circulation pump; the primary RO device, the secondary RO device, and the concentrated water RO membrane device are all equipped with a high-pressure pump, a membrane assembly, and a pressure control instrument; S2: Micro-electrolysis reaction, the electroplating wastewater is discharged into the collection tank and passed through the pretreatment unit. The lifting pump transports the electroplating wastewater through the micro-electrolysis reactor. The micro-electrolysis reactor aerates and mixes the electroplating wastewater through the aeration mixing device. The wastewater enters the pool equipped with micro-electrolysis fillers under acidic conditions. The micro-electrolysis fillers undergo redox reactions under acidic conditions to produce highly oxidizing free radicals, which break down the macromolecular organic matter in the water into small molecular organic matter, which is used to efficiently remove COD, reduce chroma, and improve biodegradability; S3: Advanced oxidation reaction. After the electroplating wastewater undergoes micro-electrolysis, it enters the advanced oxidation reaction. Hydrogen peroxide is added to the water pool for reaction. The two reagents, ferrous sulfate produced by the micro-electrolysis reaction and the added hydrogen peroxide, react under acidic pH conditions to generate highly oxidizing OH- ions, which are used to break the chemical chain of organic matter in the water, converting large organic matter into small molecular organic matter, and reducing the organic matter content of the wastewater. S4: Filtration treatment: the effluent after the advanced oxidation reaction enters the quartz sand filtration, activated carbon filtration and ultrafiltration device in sequence to further remove impurities and colloids in the water, and then enters the membrane treatment process; S5: Membrane treatment. The electroplating wastewater after pretreatment enters the primary RO device. The effluent of the primary RO device enters the secondary RO device. Organic matter and salt are removed in the primary RO device and the secondary RO device. The effluent of the secondary RO device is reused for production. The salt and organic solution intercepted by the primary RO membrane are discharged as concentrated water of the membrane and enter the concentrated water RO membrane device. It is further filtered in the concentrated water RO membrane device. The effluent of the concentrated water RO membrane is reused, and the concentrated water enters the concentrated water RO membrane device for filtration again. The produced water produced by the concentrated water RO device is used for reuse production, and the concentrated water enters the evaporation device for evaporation. S6: Evaporation treatment: the solution in the evaporation device is heated to 100°C and circulated continuously in the evaporation chamber of the evaporation device through a circulation pump. The water in the wastewater evaporates and separates from the pollutants, the organic matter and salt form solids, and the water vapor is condensed into water for reuse.

2. A zero-discharge process for membrane separation of electroplating wastewater according to claim 1, characterized in that: In S1, the pretreatment unit includes coagulation sedimentation, micro-electrolysis filler, Fenton chemical oxidation, sand filtration, carbon filtration, and ultrafiltration, which are used to remove organic matter, heavy metals, and particulate matter in electroplating wastewater.

3. A zero-discharge process for membrane separation of electroplating wastewater according to claim 1, characterized in that: In the S5, the primary RO device adopts Hyde Energy's low-pressure anti-pollution reverse osmosis membrane, including one of PRO-XR1 and PROC30, with a filtration pressure of 1.5-3.0 MPA and a recovery rate of 70-75%; the secondary RO device adopts Hyde Energy's low-pressure anti-pollution reverse osmosis membrane, with a filtration pressure of 1.5-1.8 MPA and a recovery rate of 75-80%; the concentrated water RO membrane adopts one of Hyde Energy's medium-pressure and high-pressure anti-pollution reverse osmosis membranes, with a filtration pressure of 2.5-4.0 MPA and a recovery rate of 65-70%. The primary RO device, the secondary RO device, and the concentrated water RO membrane device are cleaned with hydrochloric acid and sodium hydroxide after being used for 1-2 years.

4. A zero-discharge process for membrane separation of electroplating wastewater according to claim 1, characterized in that: In S6, the solution in the evaporation device is heated to 100°C using either electricity or steam.

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