CN212403790U - System for treating comprehensive wastewater generated by anodic oxidation process - Google Patents
System for treating comprehensive wastewater generated by anodic oxidation process Download PDFInfo
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Abstract
A system for treating comprehensive wastewater generated by an anodic oxidation process, which has simple structure, flow line treatment and good treatment effect. The method adopts a filtering device and an RO reverse osmosis treatment module to carry out concentration treatment on mixed wastewater, then the concentrated solution and the wastewater stock solution are mixed and then are treated by a multistage three-dimensional electrolytic system, a coagulation reaction, a precipitation reaction and a microfiltration membrane system, nickel and chromium containing residual dye and in a complex state are removed, the nickel emission concentration of the treated effluent is controlled below 0.1mg/L, the total chromium concentration is below 0.5mg/L, the hexavalent chromium concentration is below 0.1mg/L, the COD concentration is below 100mg/L, and the nickel and chromium recovery rate is above 90%. The reuse rate of the mixed wastewater after the RO reverse osmosis technology reaches more than 80 percent, thereby not only solving the problem of standard discharge of wastewater comprehensive treatment, but also recycling the wastewater and reducing the wastewater treatment cost.
Description
Technical Field
The utility model relates to the technical field of industrial wastewater treatment, in particular to an anodic oxidation nickel/chromium-containing wastewater treatment device and a treatment method.
Background
In general, metal members such as aluminum members are mostly subjected to an anodizing surface treatment process in order to have better surface characteristics and gloss. The metal after the anodic oxidation surface treatment can improve the hardness and the wear resistance, has good heat resistance and excellent insulation, can enhance the corrosion resistance, and can be colored into various colors. The process is widely applied to shells of electronic articles, shells of ornaments and the like at present, and along with the popularization of products, in the process of expanding the production capacity of various production enterprises, a large amount of toxic and harmful wastewater is respectively generated due to surface treatment and water washing process flows, and the wastewater comprises coloring wastewater and chromium/nickel-containing wastewater (hereinafter, the toxic and harmful wastewater is simply referred to as comprehensive wastewater), so the environmental protection requirement of the production enterprises on the comprehensive wastewater treatment is increased.
The anodic oxidation surface treatment process mainly comprises the processes of stamping, grinding, degreasing, chemical polishing, anodic oxidation, coloring, hole sealing, rinsing with clear water and the like, wherein,
in the coloring process, a product is colored by using a metal complex dye, so that residual dye is contained in coloring wastewater, the chromaticity and COD of the comprehensive wastewater are high, and heavy metal is contained, wherein the chromium-containing dye is a common metal dye;
in the hole sealing process, nickel acetate is mostly used as a hole sealing agent to carry out surface hole sealing treatment on the metal component of the plated part, so that hole sealing wastewater contains heavy metal nickel.
The water quality of the wastewater discharged from the two procedures of coloring and hole sealing not only contains heavy metal nickel/chromium, but also contains high-concentration COD, and the water quality is complex and the treatment difficulty is large. The currently common method for treating nickel/chromium-containing wastewater by anodic oxidation is a chemical precipitation method, namely, lime is used for adjusting the pH value of the nickel-containing wastewater, and a metal collecting agent is added for neutralization, coagulation, flocculation and precipitation. Further, there are ion exchange method, adsorption method, electrodialysis method, evaporation concentration method, reverse osmosis method and the like.
CN201620614995.5 discloses a system for treating and recycling the washing water produced by aluminum anodic oxidation, and the concentrated solution and the concentrated water after recycling are treated by adopting a mode of independent treatment of entrusted units. Aiming at the problems of high equipment cost and high operation cost of the existing treatment mode and the difficulty of treated concentrated solution, most enterprises adopt evaporation concentration to treat the concentrated solution, the evaporator is easy to block and break due to the complexity of the nickel/chromium anodic oxide wastewater, and the price of the evaporator is high.
In conclusion, the development of a device and a method for treating nickel/chromium-containing wastewater by anodic oxidation, which have simple structure and good treatment effect, is a problem to be solved urgently by the technical personnel in the field.
SUMMERY OF THE UTILITY MODEL
The to-be-solved technical problem of the utility model is to provide a system for treating comprehensive waste water to anodic oxidation technology production that simple structure, assembly line are handled and treatment effect is good.
In order to solve the technical problem, the utility model discloses a technical scheme be:
the utility model discloses a system for processing nickeliferous, chromium waste water that produces anodic oxidation technology, include the processing apparatus who handles containing residual dye, heavy metal chromium and heavy metal nickel's comprehensive waste water that produces in the surface treatment flow of anodic oxidation, its characterized in that: the treatment device comprises a comprehensive wastewater collecting tank, a mixed wastewater collecting tank, a filtering tank, an RO reverse osmosis membrane treatment module and a multi-stage three-dimensional electrolysis system, wherein,
the comprehensive wastewater collection tank is used for collecting a wastewater stock solution generated after anodic oxidation surface treatment, the wastewater stock solution contains high-concentration residual dye, heavy metal nickel/chromium and COD, and a comprehensive wastewater water outlet is connected to the multistage three-dimensional electrolysis system through a pipeline;
the mixed wastewater collection tank is used for collecting mixed wastewater generated after the anodic oxidation surface treatment device and the place where the device is located are cleaned by clear water, the mixed wastewater contains residual dye with low concentration, heavy metal nickel/chromium and COD, and a mixed wastewater outlet is connected to a wastewater inlet of the filter tank through a pipeline;
the filter tank is filled with quartz sand and activated carbon which are used for removing suspended matters in the mixed wastewater and adsorbing part of COD, and a water filtration outlet of the filter tank is connected with a water filtration inlet of the RO reverse osmosis membrane treatment module;
the RO reverse osmosis membrane treatment module is composed of a high-pressure tube shell and a plurality of stages of RO membrane assemblies arranged in the tube shell, and is used for concentrating filtered wastewater treated by the filter tank, a clear water outlet of the RO reverse osmosis membrane treatment module is connected with a still water supply tank of the anodic oxidation surface treatment device, and concentrated waste liquid generated by the RO reverse osmosis membrane treatment module is discharged into a comprehensive wastewater collection tank;
the multistage three-dimensional electrolysis system is formed by connecting at least two sets of three-dimensional electrolysis devices in series, the comprehensive wastewater in the comprehensive wastewater collecting tank is pumped into the multistage three-dimensional electrolysis system, the comprehensive wastewater is deeply oxidized, organic matters are removed, the nickel in a complex state is changed into free-state divalent free nickel, and trivalent free chromium is released.
The RO membrane module is formed by connecting three stages of membrane units in series, each stage of membrane unit is provided with 10-20 membrane elements, and the membrane flux of each membrane element is 10-20L/m2·h。
The two-stage three-dimensional electrolysis system consists of a first-stage pH adjusting tank, a first-stage three-dimensional electrolysis device, a second-stage pH adjusting tank and a second-stage three-dimensional electrolysis device, wherein,
a first-stage pH adjusting tank, which is used for pumping the comprehensive wastewater in the comprehensive wastewater collecting tank into the first-stage pH adjusting tank and adjusting the pH value of the comprehensive wastewater to be beneficial to generating a strong oxidant H in a first-stage three-dimensional electrolysis device2O2The comprehensive wastewater is pumped into a first-stage three-dimensional electrolysis device by stirring uniformly in an acidic state;
the primary three-dimensional electrolysis device consists of an electrolysis bath, a cathode plate, an anode plate, a three-dimensional electrode and an aeration device, wherein the cathode plate and the anode plate are parallel to the flowing direction of the comprehensive wastewater, the three-dimensional electrode is filled between the cathode plate and the anode plate, and the aeration device is arranged at the bottom of the electrolysis bath; which is organic to the residual dye contained in the comprehensive waste water pumped thereinCarrying out primary oxidation treatment on the substances, and carrying out primary complex breaking treatment on the nickel and chromium in a complex state in the comprehensive wastewater; a secondary pH adjusting tank, which is used for pumping the comprehensive wastewater after primary oxidation and decomplexation treatment into the secondary pH adjusting tank, and adding acid liquor to keep the pH value of the comprehensive wastewater in favor of continuously generating strong oxidant H in a secondary three-dimensional electrolysis device2O2The comprehensive wastewater is pumped into a secondary three-dimensional electrolysis device by stirring uniformly in an acidic state;
the two-stage three-dimensional electrolysis device consists of an electrolysis bath, a cathode plate, an anode plate, a three-dimensional electrode and an aeration device, wherein the cathode plate and the anode plate are parallel to the flowing direction of the comprehensive wastewater, the three-dimensional electrode is filled between the cathode plate and the anode plate, and the aeration device is arranged at the bottom of the electrolysis bath; the comprehensive wastewater pumped into the comprehensive wastewater is subjected to deep oxidation treatment, and molecular chains of macromolecular organic matters difficult to degrade are broken, so that nickel and chromium in the comprehensive wastewater are completely released into free-state divalent free nickel and trivalent free chromium.
Also comprises a coagulation reaction tank, a sedimentation tank and a microfiltration membrane system, wherein,
pumping the comprehensive waste water from the deep oxidation treatment of the two-stage three-dimensional electrolytic device into a coagulation reaction tank, adding alkali to adjust the pH value to 7.5-8.5 so that the positive trivalent free chromium forms granular Cr (OH)3；
A sedimentation tank for treating the Ni (OH) containing particles by the coagulation reaction tank2And Cr (OH) into which the combined waste water is pumped, in which the granular Ni (OH) is introduced2And Cr (OH) gradually increases and rapidly settles to form the comprehensive wastewater containing a large amount of Ni (OH)2And Cr (OH)3The bottom sludge and the supernatant are in a solid-liquid separation state;
adjusting pH of the supernatant to 10.5-11 with alkali to completely form Ni (OH)2The system for microfiltration of the precipitate according to (1), wherein fine suspended matters and colloidal particles in the supernatant are filtered off.
The negative plate and the positive plate in the first-stage three-dimensional electrolysis device and the second-stage three-dimensional electrolysis device are both graphite plates; the three-dimensional electrode is carbon-based catalyst particles containing iron elements.
In the first-stage three-dimensional electrolysis device and the second-stage three-dimensional electrolysis device, the flow speed of the comprehensive wastewater is 1.5m3-2.5m3/h。
The utility model adopts the integrated wastewater collecting tank and the mixed wastewater collecting tank to separately collect the waste water stock solution containing high-concentration harmful substances directly discarded by the anodic oxidation surface treatment device and the mixed wastewater containing low-concentration harmful substances and sludge impurities generated by the subsequent cleaning of the anodic oxidation surface treatment device and the ground where the anodic oxidation surface treatment device is located, then the mixed wastewater is concentrated by adopting the special filtering device and the RO reverse osmosis treatment module, and then the concentrated solution is mixed with the waste water stock solution and is treated by the multistage three-dimensional electrolytic system, the coagulation reaction, the precipitation reaction and the microfiltration membrane system, nickel and chromium containing residual dye and complex state are removed, so that the nickel emission concentration of the treated effluent is controlled below 0.1mg/L, the total chromium concentration is below 0.5mg/L, the hexavalent chromium concentration is below 0.1mg/L, and the COD concentration is below 100mg/L, the recovery rate of nickel and chromium is above 90%.
The utility model discloses to synthesize waste water treatment to reach standard and retrieval and utilization and combine organically, the still water rate of reuse of mixed waste water behind RO reverse osmosis technique reaches more than 80%, has both solved waste water comprehensive treatment discharge problems to reach standard, makes waste water cyclic utilization again, reduces the waste water treatment cost.
Drawings
Fig. 1 is a block diagram of a processing system according to the present invention.
Detailed Description
As shown in figure 1, the system for treating the nickel and chromium-containing wastewater generated by the anodic oxidation process comprises a front treatment system and a tail treatment system.
The comprehensive wastewater is formed by mixing a wastewater stock solution and mixed wastewater, wherein the wastewater stock solution is waste wastewater directly discharged from an anodic oxidation surface treatment device, the wastewater stock solution contains high-concentration residual dye, complex heavy metal nickel/chromium, COD (chemical oxygen demand) and other harmful substances, the mixed wastewater is wastewater generated by cleaning the anodic oxidation surface treatment device and the place (including the ground) where the device is located with clear water after the wastewater stock solution is discharged, and the mixed wastewater contains low-concentration residual dye, complex heavy metal nickel/chromium, COD, sludge impurities and other harmful substances.
The pre-treatment system consists of a comprehensive wastewater collecting tank, a mixed wastewater collecting tank, a filtering tank, an RO reverse osmosis membrane treatment module and a multi-stage three-dimensional electrolysis system. After the comprehensive wastewater is treated by the pre-treatment system, most organic matters in the comprehensive wastewater can be oxidized and decomposed, so that the nickel and the chromium in a complex state are broken into free-state divalent free nickel and trivalent free chromium, and a better foundation is laid for the subsequent continuous treatment.
The final treatment system consists of a coagulation reaction tank, a sedimentation tank, a nickel precipitation tank, a microfiltration membrane system and a two-stage ion exchange system. After the comprehensive wastewater treated by the pre-treatment system is treated by the ending treatment system, nickel and chromium in the comprehensive wastewater are recovered and treated in the form of solid sludge, and the treated effluent is discharged in order to reach the discharge limit value specified in the third Specification of the discharge Standard of electroplating pollutants (GB 21900-2008).
One, front treatment system (also called electrocatalysis treatment unit)
1. And the comprehensive wastewater collecting tank is used for collecting the wastewater stock solution. The wastewater inlet of the comprehensive wastewater collecting tank is connected with the liquid outlet of the anodic oxidation surface treatment device through a pipeline, and the wastewater outlet of the comprehensive wastewater collecting tank is connected with the wastewater inlet of the multistage three-dimensional electrolysis system through a pipeline.
A stirring device is arranged in the comprehensive wastewater collecting tank, and electric control valves for automatically controlling flow are arranged on the pipelines.
2. And the mixed wastewater collecting tank is used for collecting the mixed wastewater. The waste water inlet of the mixed waste water collecting pool is respectively connected with the liquid outlet of the anodic oxidation surface treatment device and the waste water drain outlet of the place where the anodic oxidation surface treatment device is positioned through pipelines, and the waste water outlet of the mixed waste water collecting pool is connected with the waste water inlet of the filter tank through a pipeline.
And electric control valves for automatically controlling the flow are arranged on the pipelines connected with the mixed wastewater collecting tank.
3. And the filter tank is filled with quartz sand and activated carbon and is used for carrying out primary filtration on the mixed wastewater, and the filter tank can filter suspended matters in the mixed wastewater and adsorb part of COD in the mixed wastewater. The waste water outlet of the RO reverse osmosis membrane treatment module is connected with the waste water inlet of the RO reverse osmosis membrane treatment module.
4. And the RO reverse osmosis membrane treatment module is used for concentrating the mixed wastewater filtered by the filter tank. The RO membrane assembly comprises a high-pressure pipe shell and RO membrane elements, wherein the RO membrane assembly is formed by connecting at least two stages of RO membrane units in series, each stage of RO membrane unit is provided with 10-20 membrane elements, and the membrane flux of each membrane element is 10-20L/m2H, 8040 of tubular high-pollution RO membrane elements are selected as the membrane elements.
In the concentration process in the RO reverse osmosis membrane treatment module, dialysis water (also called clean water) generated by mixed wastewater passing through a preceding RO membrane unit is input into a still water supply tank (also called a recycling tank of the anodic oxidation surface treatment device) of the anodic oxidation surface treatment device through a dialysis water outlet and a pipeline. Concentrated solution generated by each stage of RO membrane unit is discharged through a concentrated solution outlet and then sequentially enters a next stage of RO membrane unit, and concentrated solution of the last stage of RO membrane unit is pumped into the comprehensive wastewater collecting tank through a pipeline.
The RO reverse osmosis membrane treatment module adopts an RO reverse osmosis technology, the technology is an efficient industrial wastewater treatment technology, the effluent generated after the industrial wastewater is treated by the RO reverse osmosis membrane treatment module can be directly recycled to a production line, and the part containing high-concentration substances with the water inflow of about 25 percent becomes concentrated solution to be remained for subsequent treatment. At present, concentrated solution treatment methods generated by RO reverse osmosis technology comprise evaporation concentration and advanced oxidation, the evaporation concentration cost is high, and partial residues still exist after evaporation; the cost of treatment with a single advanced oxidation technique is also quite high.
5. The multistage three-dimensional electrolysis system consists of a primary pH adjusting tank, a primary three-dimensional electrolysis device, a secondary pH adjusting tank and a secondary three-dimensional electrolysis device.
1) And the primary pH adjusting tank is used for collecting the comprehensive wastewater in the comprehensive wastewater collecting tank, adjusting the pH value of the comprehensive wastewater to a strong acid state, wherein the pH value is 3-5, and the pH value can be adjusted by adopting a pH automatic controller to automatically add acid amount into the primary pH adjusting tank. Pumping the uniformly stirred comprehensive wastewater into a first-stage three-dimensional electrolysis device.
The strong acid state can pump the comprehensive wastewater into a first-stage three-dimensional electrolysis device to be convenient for generating a large amount of strong oxidant H2O2。
2) The first-stage three-dimensional electrolysis device consists of an electrolysis bath, a cathode plate, an anode plate, a three-dimensional electrode and an aeration device, wherein the comprehensive wastewater flows in from one side of the electrolysis device and then flows out from the other side of the electrolysis device, and the cathode plate and the anode plate are parallel to the flow direction of the comprehensive wastewater.
The three-dimensional electrode is iron-containing carbon-based catalyst particles (synthetic particles which are prepared by taking activated carbon as a base material and loading an active catalyst and an oxidant), and is filled between a cathode plate and an anode plate to form the three-dimensional electrode.
The aeration device is arranged at the bottom of the electrolytic bath and has the following functions: on one hand, the aeration stirring can prevent pollutants from attaching to the surface of the particle electrode, so that the electrocatalytic oxidation efficiency is reduced; on the other hand, the dissolved oxygen content can be increased in the aeration process, the generation rate of OH free radicals is accelerated, and the oxidative decomposition of organic matters is accelerated.
The primary three-dimensional electrolysis device enables organic matters containing residual dyes in comprehensive wastewater to be subjected to primary oxidation treatment under the electrolysis environment of 35-40V of electrolysis voltage and an aeration process, and enables nickel and chromium in a complex state in the comprehensive wastewater to be subjected to primary complex breaking treatment.
The electrolysis principle is as follows:
loss of Fe electrons in three-dimensional electrodes to produce Fe2+Molecular oxygen to produce H by electron reduction2O2Rapidly react with Fe2+The reaction forms OH and Fe with strong oxidizability3+。
OH can oxidize and decompose macromolecular organic matters in the wastewater into small molecules, complex nickel breaks the complex, and particularly, unsaturated bonds of chromium-containing dye molecules which are difficult to degrade can be broken to break the structures of chromophoric groups and chromophoric groups. Free Ni for making Ni and Cr in complex state into free state2+And Cr3+. Under acidic conditions, molecular oxygen is more prone to produce H2O2With addition of Fe2+Presence of H2O2The speed of converting into OH free radicals is accelerated, the removal rate is improved, and the electrocatalytic oxidation effect is better under the acidic condition.
In addition, the three-dimensional electrode is carbon-based catalyst particles which have a pore structure, and the pore structure can better adsorb colored dye molecules, so that the aim of removing chromaticity is fulfilled.
The waste water has large chroma and is caused by colored pollutants of toxic substances. Generally, the pollution factors related to colored contaminants are expressed in terms of color.
The reaction process of the first-stage three-dimensional electrolysis is as follows:
H2O→·OH+H++e－ (1)
O2+2H++2e－→H2O2 (2)
Fe－2e－→Fe2+ (3)
Fe2++H2O2→Fe3++·OH+OH－ (4)
·OH+RH→·R+H2O (5)
Fe3++OH－→Fe(OH)3 (6)
wherein RH represents an organic substance, and R represents an organic radical.
3) The pH value of the comprehensive wastewater subjected to the electrolytic treatment by the primary three-dimensional electrolytic device in the secondary pH adjusting tank is increased, and when the pH value is close to neutral or alkaline, hydroxyl free radicals cannot be generated in the whole process, so that the oxidability is reduced. In order to keep the comprehensive wastewater under strong acid, the comprehensive wastewater after primary oxidation and complex breaking treatment is pumped into the secondary pH adjusting tank, the pH value of the comprehensive wastewater is kept in a strong acid state by adding acid liquor, the pH value is kept at 3-5, and the pH value can be adjusted by automatically adding acid amount into the secondary pH adjusting tank by adopting a pH automatic controller.
The comprehensive wastewater is pumped into a secondary three-dimensional electrolysis device after being uniformly stirred.
4) The structure and the adopted three-dimensional electrode of the secondary three-dimensional electrolysis device are the same as those of the primary three-dimensional electrolysis device.
The two-stage three-dimensional electrolysis device carries out deep oxidation treatment on organic matters in the comprehensive wastewater pumped into the two-stage three-dimensional electrolysis device under the electrolysis environment of 40-45V of electrolysis voltage and an aeration process, breaks down molecular chains of macromolecular organic matters which are difficult to degrade, simultaneously completely releases nickel in the comprehensive wastewater into free-state divalent free nickel, and breaks down chelating combination of dyes to release trivalent free chromium. And trivalent free chromium.
The three-dimensional electrodes in the first-stage three-dimensional electrolysis device destroy long-chain organic matters under the excitation of low voltage to enable the long-chain organic matters to become short-chain organic matters; the particle electrode in the secondary three-dimensional electrolytic device thoroughly mineralizes short-chain organic matters under the excitation of high voltage, releases nickel ions and destroys azo structures of dyes.
In the first-stage three-dimensional electrolysis device and the second-stage three-dimensional electrolysis device, the treatment mode of the comprehensive wastewater is a flowing treatment mode, and the flowing speed of the comprehensive wastewater is 1.5m3-2.5m3/h
Second, ending processing system
1. Coagulation reaction tank
And (3) pumping the comprehensive wastewater subjected to deep oxidation treatment by the secondary three-dimensional electrolysis device into the coagulation reaction tank, adding alkali to adjust the pH value to 7.5-8.5, and automatically adding the amount of alkali into the coagulation reaction tank by using a pH automatic controller.
Under alkaline environment, the divalent free nickel and the trivalent free chromium respectively form precipitated granular Ni (OH)2And Cr (OH)3. In addition, after the treatment of the two-stage three-dimensional electrolysis system, excellent colloidal flocculant Fe (OH) is generated in the comprehensive wastewater3The colloid flocculant is Fe (OH)3Can be paired with Ni (OH)2And Cr (OH)3Adsorbing and trapping, adding small amount of organic polymer flocculant to obtain granular Ni (OH)2And Cr (OH)3The water quickly grows up, so that the subsequent precipitation is facilitated, and the sludge-water separation of the comprehensive wastewater is realized.
2. Sedimentation tank
A sedimentation tank for containing the water treated by the coagulation reaction tankWith particulate Ni (OH)2And pumping the comprehensive wastewater of Cr (OH) into the coagulation reaction tank, adding alkali to adjust the pH value to 10-11, and automatically adding the amount of alkali into the coagulation reaction tank by using a pH automatic controller.
As mentioned above, in alkaline environment, granular Ni (OH)2And Cr (OH) gradually increases and rapidly settles to form the comprehensive wastewater containing a large amount of Ni (OH)2And Cr (OH)3The bottom sludge and the supernatant liquid are in a coexistent solid-liquid separation state, and the bottom sludge containing high-concentration heavy metal nickel and chromium is sent to a nickel/chromium recovery device for retreatment.
3. A nickel precipitation pool, the supernatant in the precipitation pool is injected into the nickel precipitation pool, the pH value is adjusted to 10-11, and the residual nickel ions in the supernatant are further generated into granular Ni (OH)2And (4) precipitating.
4. Microfiltration membrane system
And the microfiltration membrane system is used for filtering fine suspended matters and colloidal particles in the supernatant in the nickel precipitation tank so as to clarify the filtered wastewater.
The microfiltration membrane system comprises a polyvinyl chloride microfiltration membrane shell and a polyvinylidene fluoride microfiltration membrane core. The filtering aperture of the micro-filtration membrane core is 0.1-10 μm.
4. Two-stage ion exchange system
The device consists of a nickel ion exchange column and a chromium ion exchange column which are connected in series and is used for further adsorbing and filtering trace turbidity, organic matters and heavy metals of the wastewater.
And (3) sequentially injecting the wastewater clarified liquid from which the fine suspended solids and the colloidal particles are filtered into a nickel ion exchange column and a chromium ion exchange column, wherein the effluent treated by the two-stage ion exchange system can reach the discharge limit value specified in the three standards of the national standard GB21900-2008 for discharge of electroplating pollutants, and discharging the standard wastewater into a municipal drainage network.
The nickel precipitation tank, the microfiltration membrane system and the two-stage ion exchange system are called as trace adsorption units.
Examples
The treatment system and the treatment method of the utility model are adopted to treat the comprehensive wastewater (namely the wastewater stock solution and the mixed wastewater) generated by the hole sealing and coloring procedures of a certain anodic oxidation production line.
The indexes of the comprehensive wastewater are as follows: pH value: 5.512, conductivity: 2.18ms/cm, total nickel: 660mg/L, total chromium: 6.25mg/L, COD: 1933.53 mg/L.
Adopt multistage RO reverse osmosis membrane treatment module to carry out reverse osmosis filtration to mixed waste water, reverse osmosis goes out water: pH: 6.5, conductivity: 0.018ms/cm, total nickel: 0.012mg/L, total chromium: 0.005mg/L, COD: 50 mg/L. And recycling the mixture to an anode oxidation production line.
And (3) injecting a concentrated solution generated after the mixed wastewater is concentrated by the RO reverse osmosis membrane treatment module into the comprehensive wastewater collecting tank and mixing with a wastewater stock solution, adding sulfuric acid to adjust the pH value to 3.0, and carrying out electrocatalytic oxidation treatment by a two-stage three-dimensional electrolysis device. The cathode plate and the anode plate in the two-stage three-dimensional electrolysis device are graphite plates, the particle electrode is a carbon-based catalyst, the size is 1-2cm, the filling amount is 80%, and the electrolysis reaction time of the two-stage three-dimensional electrolysis device is 1 hour.
And the effluent of the secondary three-dimensional electrolysis device enters a coagulation reaction tank. Sodium hydroxide is added into the coagulation reaction tank to control the pH value of the reaction to be 8.5 so as to lead Ni2+And Cr3+Forming a precipitate, and adding polyacrylamide with the adding amount of 0.1kg/m3The precipitated particles grow up rapidly.
And (3) the effluent of the coagulation reaction tank enters a sedimentation tank for preliminary solid-liquid separation, the bottom sludge is discharged, dried and transported outwards, and the supernatant sequentially passes through a microfiltration membrane system and an ion exchange system to further adsorb and filter trace turbidity, organic matters and heavy metals of the wastewater. Ion exchange system effluent pH: 7.5, conductivity: 8.07ms/cm, total nickel: 0.021mg/L, total chromium: 0.015mg/L, COD: 45 mg/L. Reaches the standard specified in table three of the discharge Standard of electroplating pollutants of the national Standard GB 21900-2008.
Claims (6)
1. The utility model provides a system for handle nickeliferous, chromium waste water that anodic oxidation technology produced, includes that the comprehensive waste water who contains residual dyestuff, heavy metal chromium and heavy metal nickel who produces among the anodic oxidation surface treatment process handles processing apparatus, its characterized in that: the treatment device comprises a comprehensive wastewater collecting tank, a mixed wastewater collecting tank, a filtering tank, an RO reverse osmosis membrane treatment module and a multi-stage three-dimensional electrolysis system, wherein,
the comprehensive wastewater collection tank is used for collecting a wastewater stock solution generated after anodic oxidation surface treatment, the wastewater stock solution contains high-concentration residual dye, heavy metal nickel/chromium and COD, and a comprehensive wastewater water outlet is connected to the multistage three-dimensional electrolysis system through a pipeline;
the mixed wastewater collection tank is used for collecting mixed wastewater generated after the anodic oxidation surface treatment device and the place where the device is located are cleaned by clear water, the mixed wastewater contains residual dye with low concentration, heavy metal nickel/chromium and COD, and a mixed wastewater outlet is connected to a wastewater inlet of the filter tank through a pipeline;
the filter tank is filled with quartz sand and activated carbon which are used for removing suspended matters in the mixed wastewater and adsorbing part of COD, and a water filtration outlet of the filter tank is connected with a water filtration inlet of the RO reverse osmosis membrane treatment module;
the RO reverse osmosis membrane treatment module is composed of a high-pressure tube shell and a plurality of stages of RO membrane assemblies arranged in the tube shell, and is used for concentrating filtered wastewater treated by the filter tank, a clear water outlet of the RO reverse osmosis membrane treatment module is connected with a still water supply tank of the anodic oxidation surface treatment device, and concentrated waste liquid generated by the RO reverse osmosis membrane treatment module is discharged into a comprehensive wastewater collection tank;
the multistage three-dimensional electrolysis system is formed by connecting at least two sets of three-dimensional electrolysis devices in series, the comprehensive wastewater in the comprehensive wastewater collecting tank is pumped into the multistage three-dimensional electrolysis system, the comprehensive wastewater is deeply oxidized, organic matters are removed, the nickel in a complex state is changed into free-state divalent free nickel, and trivalent free chromium is released.
2. The system for treating nickel and chromium-containing wastewater generated by anodic oxidation process according to claim 1, characterized in that: the RO membrane module is formed by connecting three stages of membrane units in series, each stage of membrane unit is provided with 10-20 membrane elements, and the membrane flux of each membrane element is 10-20L/m2·h。
3. The system for treating nickel and chromium-containing wastewater generated by anodic oxidation process according to claim 2, characterized in that: the multistage three-dimensional electrolysis system consists of a primary pH adjusting tank, a primary three-dimensional electrolysis device, a secondary pH adjusting tank and a secondary three-dimensional electrolysis device, wherein,
a first-stage pH adjusting tank, which is used for pumping the comprehensive wastewater in the comprehensive wastewater collecting tank into the first-stage pH adjusting tank and adjusting the pH value of the comprehensive wastewater to be beneficial to generating a strong oxidant H in a first-stage three-dimensional electrolysis device2O2The comprehensive wastewater is pumped into a first-stage three-dimensional electrolysis device by stirring uniformly in an acidic state;
the primary three-dimensional electrolysis device consists of an electrolysis bath, a cathode plate, an anode plate, a three-dimensional electrode and an aeration device, wherein the cathode plate and the anode plate are parallel to the flowing direction of the comprehensive wastewater, the three-dimensional electrode is filled between the cathode plate and the anode plate, and the aeration device is arranged at the bottom of the electrolysis bath; carrying out primary oxidation treatment on organic matters including residual dye in the comprehensive wastewater pumped into the comprehensive wastewater, and carrying out primary complex breaking treatment on nickel and chromium in a complex state in the comprehensive wastewater; a secondary pH adjusting tank, which is used for pumping the comprehensive wastewater after primary oxidation and decomplexation treatment into the secondary pH adjusting tank, and adding acid liquor to keep the pH value of the comprehensive wastewater in favor of continuously generating strong oxidant H in a secondary three-dimensional electrolysis device2O2The comprehensive wastewater is pumped into a secondary three-dimensional electrolysis device by stirring uniformly in an acidic state;
the two-stage three-dimensional electrolysis device consists of an electrolysis bath, a cathode plate, an anode plate, a three-dimensional electrode and an aeration device, wherein the cathode plate and the anode plate are parallel to the flowing direction of the comprehensive wastewater, the three-dimensional electrode is filled between the cathode plate and the anode plate, and the aeration device is arranged at the bottom of the electrolysis bath; the comprehensive wastewater pumped into the comprehensive wastewater is subjected to deep oxidation treatment, and molecular chains of macromolecular organic matters difficult to degrade are broken, so that nickel and chromium in the comprehensive wastewater are completely released into free-state divalent free nickel and trivalent free chromium.
4. The system for treating nickel and chromium-containing wastewater generated by anodic oxidation process according to claim 3, characterized in that: also comprises a coagulation reaction tank, a sedimentation tank and a microfiltration membrane system, wherein,
pumping the comprehensive waste water from the deep oxidation treatment of the two-stage three-dimensional electrolytic device into a coagulation reaction tank, adding alkali to adjust the pH value to 7.5-8.5 so that the positive trivalent free chromium forms granular Cr (OH)3；
A sedimentation tank for treating the Ni (OH) containing particles by the coagulation reaction tank2And Cr (OH) into which the combined waste water is pumped, in which the granular Ni (OH) is introduced2And Cr (OH) gradually increases and rapidly settles to form the comprehensive wastewater containing a large amount of Ni (OH)2And Cr (OH)3The bottom sludge and the supernatant are in a solid-liquid separation state;
adjusting pH of the supernatant to 10.5-11 with alkali to completely form Ni (OH)2The system for microfiltration of the precipitate according to (1), wherein fine suspended matters and colloidal particles in the supernatant are filtered off.
5. The system for treating nickel and chromium-containing wastewater generated by anodic oxidation process according to claim 4, characterized in that: the negative plate and the positive plate in the first-stage three-dimensional electrolysis device and the second-stage three-dimensional electrolysis device are both graphite plates; the three-dimensional electrode is carbon-based catalyst particles containing iron elements.
6. The system for treating nickel and chromium-containing wastewater generated by anodic oxidation process according to claim 5, characterized in that: in the first-stage three-dimensional electrolysis device and the second-stage three-dimensional electrolysis device, the flow speed of the comprehensive wastewater is 1.5m3-2.5m3/h。
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