Electroplating wastewater treatment process and aeration equipment thereof

Abstract

The invention relates to the technical field of wastewater treatment, and provides an electroplating wastewater treatment process and aeration equipment thereof.The electroplating wastewater treatment process comprises the following steps that S1, pretreatment is conducted, specifically, electroplating wastewater is introduced into a grating device to remove large-particle impurities to obtain roughly-filtered wastewater, the roughly-filtered wastewater is fed into an adjusting tank to adjust the pH value to 6.0-8.0, an aeration device is arranged in the adjusting tank, and the aeration device is arranged in the adjusting tank; the water temperature is controlled to be 20-35 DEG C, and after impurities are precipitated, the pretreated wastewater is obtained. According to the invention, the defects of the prior art are overcome, the design is reasonable, the structure is compact, the removal rate of heavy metal ions is up to 99% or above through multi-stage cooperation of pretreatment, ultrafiltration, electrolysis and nanofiltration, the effluent quality is excellent, and up-to-standard discharge or reuse can be realized. And heavy metals can be recovered from the cathode of the electrolytic cell, and heavy metal salts are recovered from the nanofiltration concentrated solution through evaporative crystallization, so that waste recycling is realized, and the treatment cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a plating wastewater treatment process and an aeration equipment thereof. BACKGROUND

[0002] The electroplating industry is an indispensable basic industry in the national economy, but it is also one of the heavy pollution industries. The electroplating wastewater is complex in composition and usually contains chromium, cadmium, nickel, copper, zinc and other heavy metal ions. If it is directly discharged without proper treatment, it will cause serious and lasting harm to the water environment and human health.

[0003] At present, for the treatment of electroplating wastewater, common methods include chemical precipitation method, ion exchange method, adsorption method, membrane separation method and electrolysis method. Although the chemical precipitation method (such as hydroxide precipitation) has low cost, it produces a large amount of sludge and is easy to cause secondary pollution. The ion exchange method and the adsorption method have high treatment cost, and the regeneration and disposal of resin or adsorbent are troublesome. Single membrane separation technology, especially ultrafiltration and nanofiltration, can effectively intercept suspended solids and part of ions, but the membrane assembly is easily contaminated, has a short service life, and has very high requirements for pretreatment. The treatment of concentrated liquid is also a difficult problem. The electrolysis method can directly recover heavy metals, but if there are many suspended solids and impurities in the wastewater, it will seriously affect the electrode efficiency and service life. In practical application, a single treatment technology is often difficult to meet the increasingly strict discharge and reuse standards. Therefore, we propose a plating wastewater treatment process and an aeration equipment thereof. SUMMARY

[0004] In view of the shortcomings of the prior art, the present application provides a plating wastewater treatment process and an aeration equipment thereof, which overcomes the shortcomings of the prior art, has reasonable design, compact structure, and solves the problem that the existing electroplating wastewater is difficult to meet the discharge and reuse standards by a single treatment technology.

[0005] To achieve the above purpose, the present application is realized by the following technical scheme: a plating wastewater treatment process, comprising the following steps:

[0006] S1, a pretreatment step: introducing the electroplating wastewater into a grid device to remove large particle impurities, obtaining coarse filtration wastewater, and sending the coarse filtration wastewater into a conditioning tank to adjust the pH value to 6.0-8.0. An aeration device is arranged in the conditioning tank, and the water temperature is controlled at 20-35℃. After the impurities are precipitated, pretreated wastewater is obtained;

[0007] S2, a membrane separation treatment step: pumping the pretreated wastewater into an ultrafiltration membrane separation system, controlling the operating pressure to be 0.1-0.3MPa, and the membrane surface flow rate to be 1.0-2.0m / s, intercepting and removing suspended solids, colloidal particles and part of macromolecular organic matter in the wastewater, and obtaining ultrafiltration water;

[0008] S3, electrolytic treatment step: the ultrafiltration water is sent into an electrolytic tank, a titanium-based coating anode and a stainless steel cathode are arranged in the electrolytic tank, the distance between the two electrode plates is 5-25 mm, the electrolytic current density is controlled to be 50-200 A / m2, the electrolytic time is 30-90 min, and the solution is uniformly mixed through a stirring device during the electrolytic process, so that heavy metal ions in the wastewater are deposited at the cathode and organic matter is oxidized and degraded at the anode, to obtain electrolytic treatment liquid;

[0009] S4, deep membrane separation step: the electrolytic treatment liquid is sent into a nanofiltration membrane separation system, the operation pressure is controlled to be 1.0-2.5 MPa and the operation temperature is controlled to be 25-35℃, the heavy metal ions and residual organic matter that are not completely removed are intercepted and concentrated, to obtain nanofiltration water and concentrated liquid;

[0010] S5, product treatment step: the nanofiltration water is sterilized and discharged or reused after reaching the standard, and the concentrated liquid is sent into an evaporation crystallization device to recover heavy metal salt, and the heavy metal deposited at the cathode of the electrolytic tank is recovered and utilized after being washed by water flow and dried in a drying oven.

[0011] Preferably, the aeration intensity of the aeration device in the adjusting tank in the step S1 is 0.5-1.5 m3 / (m2·h), and the adjusting time is 20-40 min.

[0012] Preferably, the hollow fiber ultrafiltration membrane is used in the ultrafiltration membrane separation system in the step S2, the membrane pore size is 0.01-0.1 μm, the molecular weight cut-off is 10000-50000 Da, the backwashing is performed every 30-60 min during the ultrafiltration process, the backwashing pressure is 0.3-0.5 MPa, and the backwashing time is 30-60 s.

[0013] Preferably, the coating of the titanium-based coating anode in the step S3 is a RuO2-IrO2-TiO2 composite coating, and the coating thickness is 5-15 μm; the stirring device adopts mechanical stirring, the stirring speed is 100-300 r / min, and the pH value of the solution is monitored in real time during the electrolytic process, and when the pH value is lower than 5.0 or higher than 9.0, acid or alkali is supplemented into the electrolytic tank for adjustment.

[0014] Preferably, the nanofiltration membrane separation system in the step S4 adopts a roll-type nanofiltration membrane, the molecular weight cut-off is 100-1000 Da, the cross-flow filtration mode is used in the nanofiltration process, the cross-flow speed is 0.5-1.5 m / s, chemical cleaning is performed every 2-4 h, the cleaning liquid is a citric acid solution or a NaOH solution with a mass concentration of 0.5-2.0%, and the cleaning time is 30-60 min.

[0015] Preferably, the disinfection treatment in step S5 adopts ultraviolet disinfection or ozone disinfection, the ultraviolet disinfection dose is 20-40 mJ / cm2, and the ozone disinfection adopts ozone dosage of 5-15 mg / L; the evaporation crystallization device adopts a multi-effect evaporation crystallizer, the evaporation temperature is 45-60 DEG C, and the vacuum degree is-0.06 to-0.09 MPa.

[0016] Preferably, the sludge treatment step is further included, that is, the backwashing sludge generated by the ultrafiltration membrane separation system, the sludge precipitated in the adjusting tank and the large-particle impurities removed by the grid device are sent to a plate-and-frame filter press for dewatering treatment, the filter pressing pressure is 1.0-2.0 MPa, the water content of the dewatered sludge is controlled to be below 60%, and the dewatered sludge is sent to a hazardous waste treatment center for disposal.

[0017] Preferably, the electrolytic tank in step S3 adopts a continuous operation mode, the hydraulic retention time is controlled to be 30-90 min, a water quality monitoring module is arranged at the outlet of the electrolytic tank, and the concentrations of COD and heavy metal ions are monitored in real time; when the monitoring indexes do not meet the standards, the electrolytic treatment liquid is returned to the electrolytic tank for reprocessing.

[0018] An aeration equipment comprises a base and a rotary aeration unit;

[0019] The rotary aeration unit comprises a rotary disc rotatably arranged on the base, and the outer wall of the rotary disc is circumferentially provided with an outwardly extending exhaust pipe, and a plurality of exhaust holes are arranged on one side of the exhaust pipe.

[0020] The outer wall of the base is provided with an air inlet pipe, and the air inlet pipe, the inner cavity of the base, the exhaust pipe and the exhaust holes are communicated.

[0021] Preferably, a top cover is sleeved on the rotary disc, the inside of the top cover is provided with a sleeving frame, and a connecting hole is circumferentially arranged on the outer wall of the sleeving frame.

[0022] The inside of the base is provided with a connecting piece, the connecting piece comprises a stand column, a plurality of connecting plates connected with the inner wall of the base are circumferentially arranged on the outer wall of the stand column, a connecting protrusion matched with the inner wall of the sleeving frame is arranged on the top of the connecting plate, a plurality of threaded holes corresponding to the connecting holes are circumferentially arranged on the outer wall of the connecting protrusion, and the locking of the top cover and the stand column is realized by screwing in bolts.

[0023] Preferably, the connecting sleeve is further included, the inside of the connecting sleeve is provided with the connecting piece, the inner wall size of the connecting sleeve is matched with the outer wall size of the upper and lower ends of the rotary disc, and the size of the inside of the stand column is matched with the size of the outer wall of the connecting protrusion, so that the bottom of the stand column in the connecting sleeve is sleeved on the outer wall of the connecting protrusion in the base or the outer wall of the connecting protrusion in the connecting sleeve below.

[0024] Preferably, the rotating disc comprises a first ring in the middle connected with the exhaust pipe, the upper and lower sides of the first ring are provided with a second ring, the side of each second ring away from the first ring is provided with a third ring, the diameters of the first ring, the second ring and the third ring are arranged in a tapering manner, and the size of the outer wall of the third ring is adapted to the size of the inner wall of the top of the base, the upper and lower inner walls of the connecting sleeve and the inner wall of the bottom of the top cover.

[0025] The application provides an electroplating wastewater treatment process and an aeration equipment thereof.

[0026] 1. The multi-stage cooperation of "pretreatment + ultrafiltration + electrolysis + nanofiltration" has a removal rate of heavy metal ions of 99% or more, and the effluent quality is excellent, so that the discharge can meet the standard or be reused.

[0027] 2. The cathode of the electrolytic tank can recover heavy metals, and the nanofiltration concentrated liquid can recover heavy metal salts through evaporation crystallization, so that the waste is recycled, and the disposal cost is reduced.

[0028] 3. The unique rotating aeration design utilizes the jet thrust to drive rotation, greatly improves the oxygen transfer efficiency and the uniformity of gas-liquid mixing, strengthens the pretreatment effect, adopts the connecting sleeve stacking design, can flexibly increase the number and depth of the aeration units, and easily adapts to different pool depths and processing scale requirements. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a process flow diagram of the application;

[0030] Figure 2 It is a three-dimensional schematic diagram of the structure of the aeration device of the application;

[0031] Figure 3 It is a three-dimensional schematic diagram of the structure of the aeration device of the application; Figure 2 It is a three-dimensional schematic diagram of the structure of the aeration device of the application;

[0032] Figure 4 It is a three-dimensional schematic diagram of the structure of the aeration device of the application; Figure 2 It is a three-dimensional schematic diagram of the structure of the aeration device of the application;

[0033] Figure 5 It is a three-dimensional schematic diagram of the structure of the aeration device of the application;

[0034] Figure 6 It is a three-dimensional schematic diagram of the structure of the aeration device of the application;

[0035] Figure 7 It is a three-dimensional schematic diagram of the structure of the aeration device of the application;

[0036] In the figure: 1, base; 11, air inlet pipe; 2, rotating disc; 21, exhaust pipe; 22, exhaust hole; 23, first ring; 24, second ring; 25, third ring; 3, top cover; 31, sleeve frame; 32, connecting hole; 41, stand; 42, connecting plate; 43, connecting protrusion; 44, threaded hole; 5, connecting sleeve. DETAILED DESCRIPTION

[0037] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0038] Embodiment one:

[0039] Referring to the drawings Figure 1 A kind of electroplating wastewater treatment process, comprising the following steps:

[0040] S1, pretreatment step: the electroplating wastewater is introduced into mechanical grid device, grid gap is 5mm, after removing large particle impurities, the coarse filter wastewater is obtained, the coarse filter wastewater is sent into adjusting pool, by adding dilute sulfuric acid or sodium hydroxide solution, adjust pH to 7.0, adjusting pool is provided with aeration device, aeration intensity is 1.0m³ / (m²·h), adjustment time is 30min, and water temperature is controlled at 25 DEG C, after aeration stirring 35min, it is deposited 40min, after impurities natural deposition, the pretreatment wastewater is obtained;

[0041] S2, membrane separation treatment step: the pretreatment wastewater is pumped into ultrafiltration membrane separation system, the ultrafiltration membrane separation system uses hollow fiber ultrafiltration membrane, membrane pore size is 0.05 μm, molecular weight cut-off is 30000Da, control operating pressure is 0.2MPa, membrane surface flow rate is 1.5m / s, remove suspended solids, colloidal particles and part of macromolecular organic matter in wastewater, obtain ultrafiltration water, carry out once backflushing every 45min in the ultrafiltration process, backflushing pressure is 0.4MPa, backflushing time is 45s;

[0042] S3, electrolytic treatment step: the ultrafiltration water is sent into an electrolytic tank, a titanium-based coating anode and a stainless steel cathode are arranged in the electrolytic tank, the coating of the titanium-based coating anode is a RuO2-IrO2-TiO2 composite coating, the thickness of the coating is 10 μm, the distance between the two electrode plates is 15 mm, the electrolytic current density is controlled to be 125 A / m², the electrolytic time is 60 min, the solution is uniformly mixed through a stirring device during the electrolytic process, the stirring speed is 200 r / min, the heavy metal ions in the wastewater are deposited at the cathode, and the organic matter is oxidized and degraded at the anode, the pH value of the solution is monitored in real time during the electrolytic process, when the pH value is lower than 5.0 or higher than 9.0, dilute sulfuric acid or sodium hydroxide solution is supplemented into the electrolytic tank for adjustment, and electrolytic treatment liquid is obtained;

[0043] S4, deep membrane separation step: the electrolytic treatment liquid is sent into a nanofiltration membrane separation system, the nanofiltration membrane separation system adopts a roll-type nanofiltration membrane, the molecular weight cut-off is 500 Da, the operating pressure is controlled to be 1.5 MPa, the operating temperature is 30 °C, a cross-flow filtration mode is adopted, the cross-flow speed is 1.0 m / s, the heavy metal ions and residual organic matter that are not completely removed are cut off and concentrated, nanofiltration water and concentrated liquid are obtained, chemical cleaning is performed once every 3 h, the cleaning liquid is a 1.0% citric acid solution in mass concentration, and the cleaning time is 45 min;

[0044] S5, product treatment step: the nanofiltration water is disinfected and then discharged or recycled for backwashing of the ultrafiltration membrane separation system, the disinfection treatment adopts ultraviolet disinfection treatment, the ultraviolet disinfection dose is 30 mJ / cm², the concentrated liquid is sent into a multi-effect evaporation crystallization device to recover heavy metal salts, the evaporation temperature is 50 °C, the vacuum degree is -0.08 MPa, the heavy metals deposited at the cathode of the electrolytic tank are recovered and utilized after being washed by water flow and dried in a drying oven, and the drying temperature is 80 °C.

[0045] The embodiment also includes a sludge treatment step: the backwashing sludge generated by the ultrafiltration membrane separation system, the sludge precipitated in the adjusting tank and the large-particle impurities removed by the grid device are sent into a plate-and-frame filter press for dewatering treatment, the filter pressing pressure is 1.5 MPa, the water content of the dewatered sludge is controlled to be 55%, and the dewatered sludge is sent to a hazardous waste treatment center for disposal.

[0046] Example Two

[0047] The embodiment is optimized on the basis of Example 1, and focuses on the electrolytic treatment and membrane separation steps to improve the treatment efficiency and resource recovery rate.

[0048] S1, pretreatment step: similar to Example 1, but the aeration intensity of the aeration device in the adjusting tank is controlled to be 0.8 m³ / (m²·h), the adjusting time is 25 min, and the water temperature is controlled to be 30 °C. The grid device adopts an automatic cleaning grid to reduce blockage.

[0049] S2, membrane separation treatment step: the hollow fiber ultrafiltration membrane in the ultrafiltration membrane separation system has a membrane pore size of 0.02 μm, a molecular weight cut-off of 15000 Da, an operating pressure control of 0.15 MPa, and a membrane surface flow rate of 1.8 m / s. The backwashing frequency is increased to once every 30 min, the backwashing pressure is 0.45 MPa, and the backwashing time is 50 s.

[0050] S3, electrolysis treatment step: the electrolytic tank is operated in a continuous mode, and the hydraulic retention time is controlled to be 45 min. The electrolytic current density is adjusted to 150 A / m², and the electrolysis time is 40 min. The stirring speed is increased to 250 r / min. A water quality monitoring module is arranged at the outlet of the electrolytic tank to monitor the concentrations of COD and heavy metal ions online, such as an ultraviolet spectrometer and an atomic absorption spectrometer. When the concentration of COD is higher than 50 mg / L or the concentration of heavy metal ions is higher than 0.5 mg / L, the electrolytic treatment liquid is returned to the electrolytic tank for reprocessing to ensure the quality of the effluent.

[0051] S4, deep membrane separation step: the cut-off molecular weight of the spiral nanofiltration membrane is 200 Da. The operating pressure is controlled to be 2.0 MPa, the operating temperature is 28°C, and the cross-flow speed is 1.2 m / s. The chemical cleaning is changed to use a NaOH solution with a mass concentration of 1.5%, and the cleaning frequency is once every 2 h, and the cleaning time is 40 min.

[0052] S5, product treatment step: ozone disinfection is used for disinfection treatment, and the ozone dosage is 10 mg / L to enhance the degradation of residual organic matter. A three-effect evaporation crystallizer is used in the evaporation crystallization device, the evaporation temperature is 55°C, the vacuum degree is -0.07 MPa, and the recovery purity of heavy metal salt is improved.

[0053] Example Three:

[0054] This example is based on the optimization of Example 1, focusing on the electrolysis treatment and membrane separation steps to improve the treatment efficiency and resource recovery rate.

[0055] S1, pretreatment step: similar to Example 1, but the aeration intensity of the aeration device in the adjustment tank is controlled to be 1.5 m³ / (m²·h), the adjustment time is 40 min, and the water temperature is controlled to be 35°C.

[0056] S2, membrane separation treatment step: the hollow fiber ultrafiltration membrane in the ultrafiltration membrane separation system has a membrane pore size of 0.1 μm, a molecular weight cut-off of 50000 Da, an operating pressure control of 0.3 MPa, and a membrane surface flow rate of 2.0 m / s. The backwashing frequency is increased to once every 60 min, the backwashing pressure is 0.5 MPa, and the backwashing time is 60 s.

[0057] S3, electrolysis treatment step: the electrolytic tank adopts continuous operation mode, the hydraulic retention time is controlled to be 90 min. The electrolysis current density is adjusted to be 200 A / m2, the electrolysis time is 90 min. The stirring speed is 300 r / min. The water quality monitoring module is arranged at the outlet of the electrolytic tank, the COD and heavy metal ion concentration are monitored on line, such as ultraviolet spectrometer and atomic absorption spectrometer. When the COD concentration is higher than 50 mg / L or the heavy metal ion concentration is higher than 0.5 mg / L, the electrolytic treatment liquid is backflowed to the electrolytic tank for reprocessing, so as to ensure the water quality.

[0058] S4, deep membrane separation step: the molecular weight cut-off of the roll type nanofiltration membrane is 1000 Da. The operation pressure is controlled to be 2.5 MPa, the operation temperature is 35 DEG C, and the cross-flow speed is 1.5 m / s. The chemical cleaning is replaced by 2.0% NaOH solution, and the cleaning frequency is once every 4 h, and the cleaning time is 60 min.

[0059] S5, product treatment step: the disinfection treatment adopts ozone disinfection, and the ozone dosage is 15 mg / L, so as to enhance the degradation of residual organic matter. The evaporation crystallization device adopts three-effect evaporation crystallizer, the evaporation temperature is 60 DEG C, the vacuum degree is-0.09 MPa, and the recovery purity of heavy metal salt is improved.

[0060] Example four:

[0061] This embodiment is optimized on the basis of example 1, and focuses on the electrolysis treatment and membrane separation steps, so as to improve the treatment efficiency and resource recovery rate.

[0062] S1, pretreatment step: similar to example 1, but the aeration intensity of the aeration device in the adjustment tank is controlled to be 0.5 m3 / (m2.h), the adjustment time is 20 min, and the water temperature is controlled to be 20 DEG C.

[0063] S2, membrane separation treatment step: the hollow fiber ultrafiltration membrane in the ultrafiltration membrane separation system, the membrane pore size is 0.01 um, the molecular weight cut-off is 10000 Da, the operation pressure is controlled to be 0.1 MPa, and the membrane surface flow rate is 1.0 m / s. The backwashing frequency is increased to be once every 20 min, the backwashing pressure is 0.3 MPa, and the backwashing time is 30 s.

[0064] S3, electrolysis treatment step: the electrolytic tank adopts continuous operation mode, the hydraulic retention time is controlled to be 40 min. The electrolysis current density is adjusted to be 50 A / m2, the electrolysis time is 30 min. The stirring speed is 100 r / min. The water quality monitoring module is arranged at the outlet of the electrolytic tank, the COD and heavy metal ion concentration are monitored on line, such as ultraviolet spectrometer and atomic absorption spectrometer. When the COD concentration is higher than 50 mg / L or the heavy metal ion concentration is higher than 0.5 mg / L, the electrolytic treatment liquid is backflowed to the electrolytic tank for reprocessing, so as to ensure the water quality.

[0065] S4, a deep membrane separation step: the molecular weight cut-off of the spiral nanofiltration membrane is 100 Da. The operating pressure is controlled at 1.0 MPa, the operating temperature is 25℃, and the cross-flow speed is 0.5 m / s. The chemical cleaning is replaced by a 0.5% NaOH solution, and the cleaning frequency is once every 2 hours, and the cleaning time is 30 min.

[0066] S5, a product treatment step: ozone sterilization is used for disinfection treatment, and the ozone dosage is 5 mg / L to enhance the degradation of residual organic matter. A three-effect evaporation crystallizer is used in the evaporation crystallization device, the evaporation temperature is 45℃, the vacuum degree is-0.06 MPa, and the recovery purity of heavy metal salt is improved.

[0067] Comparative Example 1

[0068] The difference from Example 1 is that the pH value of the coarse filtration wastewater is not adjusted in step S1, and the rest is the same as Example 1.

[0069] Comparative Example 2

[0070] The difference from Example 1 is that step S2 is not performed, and the rest is the same as Example 1.

[0071] Comparative Example 3

[0072] The difference from Example 1 is that step S3 is not performed, and the rest is the same as Example 1.

[0073] Performance test

[0074] The treatment processes of Examples 1-4 and Comparative Examples 1-3 are used to treat electroplating wastewater, and atomic absorption spectrometry is used to detect the concentration of heavy metal ions in the electroplating wastewater before and after treatment, so as to calculate the removal rate, the removal rate (%)=(A1-A2) / A1*100%; A1 is the original concentration; A2 is the concentration after treatment, and the detection results are shown in Table 1.

[0075] Table 1:

[0076] Heavy metal removal (%) Example 1 99.69 Example 2 99.58 Example 3 99.25 Example 4 99.22 Comparative Example 1 95.22 Comparative Example 2 72.34 Comparative Example 3 70.57

[0077] As can be seen from Table 1, the removal effect of heavy metal ions in Examples 1-4 of the present application is excellent, and is significantly better than that of Comparative Examples 1-3, so the electroplating wastewater treatment process of the present application can be applied to the electroplating wastewater treatment process.

[0078] According to the heavy metal ion removal rate of Examples 1-4, it can be concluded that by using the multi-stage collaborative method of "pretreatment+ultrafiltration+electrolysis+nanofiltration", the removal rate of heavy metal ions in electroplating wastewater is as high as 99% or more, the effluent quality is excellent, and it can achieve discharge or reuse.

[0079] Embodiment five: implementation of aeration equipment

[0080] The embodiment provides a kind of aeration equipment applied to the electroplating wastewater treatment process described above, specific structure refers to the aeration equipment of attached Figures 2-7 A kind of aeration equipment, including base 1, flange is provided at the bottom of base 1, it is convenient to connect with the bolt of preset regulating pool, base 1 is equipped with multiple air inlet pipes 11, the air inlet of air inlet pipe 11 is connected with air pump, it is convenient to pass into air in base 1.

[0081] Rotary aeration unit includes rotary disc 2 rotationally arranged on base 1, the outer wall of rotary disc 2 is circumferentially provided with outwardly extending exhaust pipe 21, a plurality of exhaust holes 22 are arranged in exhaust pipe 21, the side of exhaust pipe 21 is tightened to the middle away from exhaust hole 22, to facilitate reducing the resistance that exhaust pipe 21 is received when rotating, air inlet pipe 11, the inner cavity of base 1, exhaust pipe 21, exhaust hole 22 are communicated, so that air can be discharged through the exhaust hole 22 of exhaust pipe 21 after entering base 1 from air inlet pipe 11, the air flow ejected forms reverse push to exhaust pipe 21, rotary disc 2 is rotated, on the one hand, it is convenient to stir water body, and on the other hand, it can make the air flow ejected and water body more fully mixed, improve aeration efficiency.

[0082] Rotary disc 2 is provided with top cover 3, the inside of top cover 3 is provided with rectangular sleeve frame 31, a plurality of connecting holes 32 are symmetrically arranged on the outer wall of sleeve frame 31, the inside of base 1 is provided with connecting piece, and the connecting piece includes rectangular stand column 41, the outer wall of stand column 41 is circumferentially provided with a plurality of connecting plates 42 connected with the inner wall of base 1, the top of connecting plate 42 is provided with rectangular connecting protrusion 43 matched with the inner wall of sleeve frame 31, a plurality of threaded holes 44 corresponding to connecting hole 32 are circumferentially arranged on the outer wall of connecting protrusion 43, the bolt is screwed into connecting hole 32 and threaded hole 44 from the middle of sleeve frame 31 to the outside, the locking of top cover 3 and stand column 41 is realized, to ensure the stable movement of equipment, after the bolt is unscrewed, rotary aeration unit can be quickly removed, to facilitate cleaning or replacing rotary aeration unit.

[0083] It also includes the connecting sleeve 5 of expandable aeration equipment, the connecting sleeve 5 is provided with connecting piece in the inside due to the same structure of connecting piece in the inside of base 1, the size of the inner wall of connecting sleeve 5 is matched with the size of the outer wall of rotary disc 2 upper and lower end, the size of the inner wall of stand column 41 is matched with the size of the outer wall of connecting protrusion 43, connecting sleeve 5 can be provided on connecting protrusion 43 in the inside of base 1, or multiple connecting sleeves 5 are stacked, and rotary aeration unit can be arranged between adjacent connecting sleeves 5, to expand the depth and range of aeration equipment, for example, in deep water regulating pool, the number and height of rotary aeration unit can be adjusted by stacking multiple connecting sleeves 5, which greatly improves the flexibility of equipment.

[0084] The rotating disc 2 comprises a first ring 23 in the middle connected with the exhaust pipe 21, the upper and lower sides of the first ring 23 are provided with a second ring 24, the side of each second ring 24 away from the first ring 23 is provided with a third ring 25, the diameters of the first ring 23, the second ring 24 and the third ring 25 are tapered, the size of the outer wall of the third ring 25 is adapted to the size of the inner wall of the top of the base 1, the upper and lower inner walls of the connecting sleeve 5 and the inner wall of the bottom of the top cover 3, so as to ensure that the rotating disc 2 can be stably connected with the base 1 and the connecting sleeve 5, and the ball can be arranged on the contact surface between the second ring 24 and the base 1 and the connecting sleeve 5 in order to reduce the friction.

[0085] Working principle: when the aeration equipment is used in the adjusting tank, air enters from the air inlet pipe 11, is discharged from the exhaust hole 22, and generates micro-bubbles, which drive the rotating disc 2 to rotate under the reverse action of the water body, improve the oxygen transfer efficiency and uniformity, promote the precipitation of impurities and the uniform adjustment of pH, and through the connecting sleeve 5 and the rotating aeration unit, the depth and range of the aeration equipment can be expanded, the flexibility of the equipment is greatly improved, the equipment structure is compact, easy to install and maintain, and suitable for continuous operation.

[0086] It should be noted that, in this text, relational terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of additional identical elements in the process, method, article or equipment including the element.

[0087] The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for treating electroplating wastewater, characterized in that, Includes the following steps: S1. Pretreatment steps: After the electroplating wastewater is introduced into the bar screen to remove large particulate impurities, coarse filter wastewater is obtained. The coarse filter wastewater is sent to the equalization tank to adjust the pH value to 6.0-8.

0. The equalization tank is equipped with an aeration device and the water temperature is controlled at 20-35℃. After the impurities settle, pretreated wastewater is obtained. S2. Membrane separation treatment step: The pretreated wastewater is pumped into the ultrafiltration membrane separation system, and the operating pressure is controlled at 0.1-0.3MPa and the membrane surface flow rate is 1.0-2.0m / s. The system removes suspended solids, colloidal particles and some large molecular organic matter from the wastewater to obtain ultrafiltration permeate. S3. Electrolysis treatment steps: The ultrafiltration permeate is fed into an electrolytic cell. The electrolytic cell is equipped with a titanium-coated anode and a stainless steel cathode. The distance between the two electrodes is 5-25 mm. The electrolysis current density is controlled at 50-200 A / m², and the electrolysis time is 30-90 min. During the electrolysis process, the solution is kept uniformly mixed by a stirring device, so that heavy metal ions in the wastewater are precipitated at the cathode and organic matter is oxidized and degraded at the anode to obtain the electrolytic treatment solution. S4. Deep membrane separation step: The electrolytic treatment solution is sent into the nanofiltration membrane separation system, and the operating pressure is controlled at 1.0-2.5MPa and the operating temperature is controlled at 25-35℃. The heavy metal ions and residual organic matter that are not completely removed are retained and concentrated to obtain nanofiltration permeate and concentrate. S5. Product processing steps: The nanofiltration permeate is disinfected and discharged or reused after meeting the standards. The concentrate is sent to the evaporation crystallization device to recover heavy metal salts. The heavy metals deposited at the cathode of the electrolytic cell are washed with water and dried in a drying oven before being recycled.

2. The electroplating wastewater treatment process as described in claim 1, characterized in that: In step S1, the aeration intensity of the aeration device in the regulating tank is 0.5-1.5 m³ / (m²·h), and the regulating time is 20-40 min.

3. The electroplating wastewater treatment process as described in claim 1, characterized in that: In step S2, the ultrafiltration membrane separation system uses a hollow fiber ultrafiltration membrane with a pore size of 0.01-0.1 μm and a molecular weight cutoff of 10,000-50,000 Da. During the ultrafiltration process, backwashing is performed every 30-60 minutes with a backwashing pressure of 0.3-0.5 MPa and a backwashing time of 30-60 seconds.

4. The electroplating wastewater treatment process as described in claim 1, characterized in that: In step S3, the coating of the titanium-based coated anode is a RuO2-IrO2-TiO2 composite coating with a thickness of 5-15μm. The stirring device adopts mechanical stirring with a stirring speed of 100-300r / min. The pH value of the solution is monitored in real time during electrolysis. When the pH value is lower than 5.0 or higher than 9.0, acid or alkali solution is added to the electrolytic cell for adjustment.

5. The electroplating wastewater treatment process as described in claim 1, characterized in that: In step S4, the nanofiltration membrane separation system uses a spiral wound nanofiltration membrane with a molecular weight cutoff of 100-1000 Da. Cross-flow filtration is used during nanofiltration with a cross-flow velocity of 0.5-1.5 m / s. Chemical cleaning is performed every 2-4 hours. The cleaning solution is a citric acid solution or NaOH solution with a mass concentration of 0.5-2.0%, and the cleaning time is 30-60 minutes.

6. The electroplating wastewater treatment process as described in claim 1, characterized in that: In step S5, the disinfection treatment uses ultraviolet disinfection or ozone disinfection. The ultraviolet disinfection dosage is 20-40 mJ / cm², and the ozone dosage is 5-15 mg / L. The evaporation crystallization device uses a multi-effect evaporation crystallizer with an evaporation temperature of 45-60℃ and a vacuum degree of -0.06 to -0.09 MPa.

7. The electroplating wastewater treatment process as described in claim 3, characterized in that: It also includes sludge treatment steps: the backwash sludge generated by the ultrafiltration membrane separation system, the sludge settled in the equalization tank, and the large particulate impurities removed by the bar screen are sent to the plate and frame filter press for dewatering treatment. The filter press pressure is 1.0-2.0 MPa. After dewatering, the sludge moisture content is controlled below 60%, and the dewatered sludge is sent to the hazardous waste treatment center for disposal.

8. The electroplating wastewater treatment process as described in claim 1, characterized in that: In step S3, the electrolyzer operates continuously, with the hydraulic residence time controlled at 30-90 minutes. A water quality monitoring module is installed at the outlet of the electrolyzer to monitor the concentration of COD and heavy metal ions in real time. When the monitoring indicators fail to meet the standards, the electrolyzed liquid is returned to the electrolyzer for reprocessing.

9. An aeration device, applied to the electroplating wastewater treatment process according to any one of claims 1-8, characterized in that: Includes a base (1) and a rotating aeration unit; The rotary aeration unit includes a rotary disk (2) rotatably mounted on a base (1). The outer wall of the rotary disk (2) is provided with an outwardly extending exhaust pipe (21). A number of neatly arranged exhaust holes (22) are opened on one side of the exhaust pipe (21). The outer wall of the base (1) is provided with an air inlet pipe (11), and the air inlet pipe (11), the inner cavity of the base (1), the exhaust pipe (21), and the exhaust hole (22) are connected.

10. The aeration device as described in claim 9, characterized in that: The rotating disk (2) is fitted with a top cover (3), and the top cover (3) has a socket frame (31) inside, and the outer wall of the socket frame (31) has a connecting hole (32) circumferentially opened. The base (1) is provided with a connector inside. The connector includes a column (41). The outer wall of the column (41) is provided with several connecting plates (42) that are connected to the inner wall of the base (1). The top of the connecting plate (42) is provided with a connecting protrusion (43) that is adapted to the inner wall of the sleeve frame (31). The outer wall of the connecting protrusion (43) is provided with several threaded holes (44) that correspond one-to-one with the connecting holes (32). The top cover (3) and the column (41) are locked by screwing in bolts.

11. The aeration device as described in claim 10, characterized in that: It also includes the connecting sleeve (5), the connecting sleeve (5) is provided with a connector inside, the inner wall size of the connecting sleeve (5) is adapted to the outer wall size of the upper and lower ends of the rotating disk (2), and the inner size of the column (41) is adapted to the outer wall size of the connecting protrusion (43), so that the bottom of the column (41) inside the connecting sleeve (5) is fitted on the outer wall of the connecting protrusion (43) inside the base (1) or fitted on the outer wall of the connecting protrusion (43) inside the connecting sleeve (5) below it.

12. The aeration device as described in claim 11, characterized in that: The rotating disk (2) includes a first ring (23) in the middle connected to the exhaust pipe (21). The first ring (23) is provided with a second ring (24) on both the upper and lower sides. Each second ring (24) is provided with a third ring (25) on the side away from the first ring (23). The diameters of the first ring (23), the second ring (24) and the third ring (25) are gradually decreasing. The size of the outer wall of the third ring (25) is adapted to the size of the top inner wall of the base (1), the upper and lower inner walls of the connecting sleeve (5) and the bottom inner wall of the top cover (3).

Images