CN111606519A

CN111606519A - Advanced treatment method for electroplating wastewater

Info

Publication number: CN111606519A
Application number: CN202010518367.8A
Authority: CN
Inventors: 闫娟
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-06-09
Filing date: 2020-06-09
Publication date: 2020-09-01

Abstract

The invention discloses an electroplating wastewater advanced treatment method, which comprises the following steps: step one, pretreatment; step two, coagulating sedimentation; step three, performing electrochemical-photocatalytic-ozone synergistic treatment; step four, treating the cation exchange resin column; step five, aerating a biological filter; and step six, nanofiltration and reverse osmosis treatment. The invention has the advantages of mutual matching of all process steps, compact layout, small floor area, low energy consumption, pretreatment oil removal, removal of suspended matters, cyanides and colloids by coagulating sedimentation, denitrification and dephosphorization by the cooperation of electrochemistry, photocatalysis and ozone, complete removal of organic pollutants, removal of most heavy metal ions by cation exchange resin column treatment, remarkable improvement of water quality by the aeration biofilter, reduction of the workload of a subsequent membrane system, removal of residual trace organic pollutants and heavy metal ions, and final desalination by a nanofiltration and two-stage reverse osmosis system, wherein the effluent quality meets the discharge standard of electroplating wastewater in GB 21900-2008.

Description

Advanced treatment method for electroplating wastewater

Technical Field

The invention relates to the technical field of environmental protection, in particular to an electroplating wastewater advanced treatment method.

Background

The waste water discharged in electroplating production is characterized by multiple types, complex water quality, and containing a large amount of toxic and harmful substances, such as heavy metals of chromium, cadmium, lead, nickel and the like, various surfactants, brightening agents and additives of malic acid, citric acid, aromatic aldehyde, EDTA, thiourea, alkynediol, coumarin and the like.

At present, the methodCommon electroplating wastewater treatment methods include a chemical method, a reverse dialysis method, an ion exchange method, a biological method and the like. The traditional treatment of electroplating wastewater only aims at the removal of heavy metals, and ignores other indexes such as: COD_Cr、NH₃-N, TP and the like. In addition, the traditional treatment method has the problems of complex process, large energy consumption, high cost, large occupied area, high treatment cost and the like. For example, the chemical precipitation process can remove heavy metals from electroplating wastewater, but cannot effectively remove surfactants and other organic pollutants, resulting in effluent COD_Cr、NH₃N, TP and the like, so that the development of the method for deeply treating the electroplating wastewater can thoroughly remove heavy metals, organic pollutants and other pollutants difficult to biochemically treat in the electroplating wastewater, and all indexes of the method can meet the electroplating pollutant discharge standard GB 21900-2008.

Disclosure of Invention

Aiming at the defects of the existing electroplating wastewater treatment method, the invention provides the electroplating wastewater advanced treatment method which is simple in process, low in cost and high in pollutant removal rate.

The purpose of the invention is realized by the following technical scheme:

an electroplating wastewater advanced treatment method comprises the following steps:

step one, pretreatment: homogenizing the electroplating wastewater in an adjusting tank, then entering a pH reaction tank, adjusting the pH to 4.5, then entering an oil removal device, and removing grease through a PERFECT oil removal membrane of the oil removal device;

step two, coagulating sedimentation: the effluent of the oil removal device enters a coagulation sedimentation tank, a composite flocculant is added into a stirring coagulation area of the coagulation sedimentation tank for reaction coagulation, solid-liquid separation is carried out in the sedimentation area, and the effluent of the coagulation sedimentation tank enters a subsequent working section after passing through a microfiltration HMF membrane filter;

step three, electrochemical-photocatalysis-ozone synergistic treatment: the effluent of the microfiltration HMF membrane filter enters an electrochemical-photocatalytic-ozone synergistic reactor for treatment; the reactor is made of toughened glass, a visible light source is arranged at the top of the reactor, a photocatalyst filling cavity is arranged along the central axis of the reactor and consists of a polytetrafluoroethylene fiber mesh fixed by a stainless steel framework, an airlift internal circulation structure is arranged at the middle lower part of the reactor, an electrolytic anode is arranged outside the circulation structure, an electrolytic cathode is arranged at the outermost side of the circulation structure, the electrolytic anode and the electrolytic cathode are both bottomless and uncovered cylinders, and an air inlet at the lower end of the reactor is sequentially connected with an air dissolving device and an air mixing device; the gas mixing device is respectively connected with the air pump and the ozone generator;

step four, treating the cation exchange resin column: adjusting the pH value of the effluent of the reactor to 7.0, and introducing into a cation exchange resin column; the cation exchange resin is sulfonic acid type aromatic block cation exchange resin;

step five, aerating the biological filter: introducing the effluent of the cation exchange column into a biological aerated filter for treatment; the process parameters of the biological aerated filter are as follows: normal filtering speed is 1.50-1.52m/h, forced filtering speed is 1.75-1.80m/h, and three-stage gas-water back flushing is adopted;

step six, nanofiltration and reverse osmosis treatment: after the effluent of the aeration biological tank passes through a nanofiltration system, the desalination rate reaches more than 30 percent; and then the desalting rate is more than 95 percent by double-stage reverse osmosis treatment.

Further, the compound coagulant in the second step is obtained by mixing modified sepiolite, organic bentonite gel, a bacillus megaterium SY-Z5 fermentation liquor and a bacillus subtilis LSY-ND fermentation liquor according to the mass ratio of 1:1:6: 2.

Further, the preparation method of the modified sepiolite comprises the following steps: immersing sepiolite fibers into 6mol/L hydrochloric acid for ultrasonic treatment for 20-40 min, calcining at 200-250 ℃ for 2-4 h, and then using 0.3mol/LAlCl₃Soaking the sepiolite powder in the solution for 6-12 h, and then grafting polyacrylamide to obtain the modified sepiolite.

Further, the preparation method of the organic bentonite gel comprises the following steps: crushing bentonite raw ore to 200 meshes, adding water to prepare a suspension, adding a sodium treatment agent accounting for 3% of the mass of the bentonite, stirring for 30min, separating and purifying, adding water, uniformly mixing, stirring for 2h at 60 ℃, then adding starch accounting for 30% of the mass of the bentonite, stopping heating, continuously stirring to room temperature, adding an acrylic acid solution, sequentially adding a cross-linking agent MBA and an initiator potassium persulfate, reacting for 3h at 70 ℃, soaking the prepared gel with water at room temperature, aging for 16-24 h, and freeze-drying to obtain the bentonite/calcium carbonate gel.

Further, the photocatalyst filler in the third step is glass beads loaded with the zinc-lanthanum doped titanium dioxide nanocrystalline porous membrane; the preparation method comprises the following steps: mixing zinc nitrate, lanthanum nitrate solution and titanium dioxide colloidal solution to obtain co-doped ultrafine particle colloidal solution, then dipping the glass beads in the colloidal solution, and removing the glass beads which are subjected to heat treatment in a nitrogen-filled tube furnace at the temperature of 420-480 ℃ for 30-40 min to obtain the glass beads loaded with the zinc-lanthanum doped titanium dioxide nanocrystalline porous membrane.

Further, the electrolytic anode in the third step is an ITO glass mesh electrode loaded with a chelating functionalized magnetic graphene composite material; the electrolytic cathode is a titanium net with the surface covered with a carbon film.

Further, the load of the magnetic graphene composite material loaded with the chelating functionalization on the ITO glass mesh electrode can be realized by a vertical lift film method.

Further, the preparation method of the chelating functionalized magnetic graphene composite material comprises the following steps: synthesizing ferroferric oxide modified graphene in one step by adopting a solvothermal method, and grafting polyethyleneimine and polyaspartic acid onto the ferroferric oxide modified graphene through amidation reaction.

Further, the preparation method of the sulfonic acid type aromatic block cation exchange resin in the fourth step comprises the following steps: chloromethylating the aromatic block polymer, then grafting styrene for modification, and then carrying out sulfonation reaction to obtain the product sulfonic acid type cation exchange resin.

This application is at first with electroplating effluent homogeneity, adjusts pH to 4.5, is favorable to grease and separation of water, and used PERFECT deoiling membrane has good oil resistance, and the oil clearance is greater than 99.5% after deoiling device handles, and the treatment effect is stable, can guarantee that subsequent handling does not receive the grease influence.

The compound coagulant used in the invention has no pollution to the environment, wide raw material sources and low cost, not only has the characteristics of high flocculation rate and high removal rate of suspended matters, but also can simultaneously remove organic pollutants and partial heavy metals in electroplating wastewater, and especially has good removal effect on cyanide. The Bacillus megaterium SY-Z5 fermentation liquor and the Bacillus subtilis LSY-ND fermentation liquor are reasonably mixed, so that the flocculation effect is good, and the removal rate of suspended matters can reach 99% when the mass ratio of the Bacillus megaterium SY-Z5 fermentation liquor to the Bacillus subtilis LSY-ND fermentation liquor is 3:1 in tests; the modified sepiolite is modified by acid, heat, inorganic and organic compounds, so that the removal rate of the cyanide in the coking wastewater is greatly improved by over 75 percent. Compared with the conventional bentonite, the organic bentonite gel used in the compound coagulant provided by the invention reacts to generate a polymer cross-linked structure, the organic bentonite gel has an obvious network framework and a large number of meshes, and the contained functional groups can be combined with organic matters and heavy metals, so that pollutants are removed, the polymer framework also enables the compound coagulant to be easily recovered, the compound coagulant is convenient to recycle, and the coagulation process cost is reduced. Aiming at the characteristics of complex water quality and difficult control of components of electroplating wastewater, the effluent of the coagulating sedimentation tank passes through a micro-filtration HMF membrane filter and then enters a subsequent working section, the HMF is a special membrane, the effluent turbidity effect is stable, the sludge floating phenomenon is avoided, and the subsequent working section is not influenced.

The invention realizes the degradation of the pollutants which are difficult to degrade in the electroplating wastewater in one step through the treatment of an electrochemical-photocatalysis-ozone synergistic reactor. The chelate functionalized magnetic graphene composite material loaded on the surface of the anode can adsorb pollutants, the zinc-lanthanum doped titanium dioxide nanocrystalline porous membrane loaded on the photocatalyst filler has good visible light catalytic activity, can catalyze the degradation of organic pollutants in water by utilizing natural light and visible light emitted by a light source at the top of a reactor, and under the synergistic action of ozone, H on the surfaces of the anode and the catalyst filler₂O₂、·OH、O₂ ^·-The yield of active substances is greatly improved, the destructive power to pollutants difficult to degrade is enhanced, the air-lift type internal circulation structure in the reactor not only promotes the convection of water in the reactor, but also the photocatalyst filler can continuously migrate in the photocatalyst filler cavity along with the air flow, compared with the accumulation of common fillers, the photocatalytic efficiency is obviously improved, the air-mixing device can adjust the mixing ratio of air and ozone, the gas dissolving device can improve the dissolving efficiency of ozone gas, and the ozone feeding is reducedThe reactor is let in again after adding, ozone through mixing with the air and dissolving the gas device for the utilization ratio of ozone improves greatly, and the inner loop structure can also drive ozone and pass the electrode mass transfer, has greatly improved electrochemistry degradation rate, can thoroughly degrade various organic pollutant, along with the going on of reaction, during the complex heavy metal ion is released the water gradually.

The invention carries out cation exchange resin column treatment on the effluent of the electrochemical-photocatalytic-ozone synergistic reactor, can adsorb most heavy metal ions, reduces the toxicity of the effluent, and is a precondition for the subsequent biological aerated filter treatment. The sulfonic acid type aromatic block cation exchange resin is modified by aromatic block polymer grafted polystyrene, so that the styrene content can be greatly improved, the sulfonation sites can be increased, the steric hindrance of sulfonation reaction can be reduced, the number of sulfonic acid groups can be increased, and the specific surface area of the block polymer resin can be increased, so that the ion exchange capacity and the metal ion adsorption capacity of the resin can be improved, the mechanical strength and the swelling degree of the resin can be obviously improved, and the wear resistance can be improved. The eluent after the resin is adsorbed and saturated can be reused in the plating tank after being processed, thereby realizing closed cycle and having higher resource utilization rate.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, firstly, grease is removed through pretreatment, the load of a coagulation process is reduced, full contact between a coagulant and other organic pollutants and heavy metals is facilitated, the quality of coagulation-precipitation effluent is improved, the reduction of the chromaticity of the coagulation-precipitation effluent is facilitated, and conditions are provided for electrochemical-photocatalytic-ozone synergistic treatment; the invention has the important characteristics that the membrane treatment technology is flexibly combined with other technologies, and the membrane treatment technology can be independently used as a working section and can also be used as auxiliary treatment of other technologies, thereby achieving the effects of optimizing the process, reducing the overall treatment cost and effectively improving the treatment efficiency of the electroplating wastewater.

(2) The invention has the advantages of mutual matching of all process steps, compact layout, small floor area, low energy consumption, pretreatment oil removal, removal of suspended matters, cyanides and colloids by coagulating sedimentation, complete removal of organic pollutants such as surfactants, brighteners and additives by the cooperation of electrochemistry, photocatalysis and ozone, removal of most heavy metal ions by cation exchange resin column treatment, diverse biological phases of the aeration biological filter, reasonable flora structure, synchronous biological oxidation, biological adsorption and physical interception, denitrification and dephosphorization, removal of residual trace organic matters and heavy metals, remarkable improvement of water quality, reduction of the working load of a subsequent membrane system, and final desalination by a nanofiltration and two-stage reverse osmosis system, wherein the effluent quality meets the discharge standard of electroplating wastewater in GB 21900-2008.

Drawings

FIG. 1 is a schematic diagram of an electrochemical-photocatalytic-ozone co-reactor configuration, wherein 1 is a visible light source; 2-a tail gas treatment device; 3-electrochemistry-photocatalysis-ozone synergistic reactor wall; 4-photocatalyst packing chamber; 5-an electrolytic cathode; 6-an electrolytic anode; 7-airlift internal circulation structure; 8-a direct current power supply; 9-a check valve; 10-a flow meter; 11-a gas dissolving device; 12-a gas mixing device; 13-an air pump; 14-oxygen cylinders; 15-ozone generator.

Detailed Description

To further illustrate the technical means and effects of the present invention, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

Taking electroplating wastewater generated by an electroplating factory in Henan as a treatment object, wherein the wastewater comprises 203mg/L of inlet water grease, 402mg/L of suspended matters, 1685mg/L of COD, 357mg/L of ammonia nitrogen, 423mg/L of total phosphorus, 110.6mg/L of nickel, 3.4mg/L of lead, 27mg/L of copper, 14mg/L of total chromium, 9mg/L of chromium (VI), 4.5mg/L of manganese and 4316us/cm of conductivity.

Example 1

step two, coagulating sedimentation: the effluent of the oil removal device enters a coagulating sedimentation tank, a composite flocculant is added into a stirring coagulation area of the coagulating sedimentation tank according to 1.5kg/t, the coagulation reaction is carried out, solid-liquid separation is carried out in the sedimentation area, and the effluent of the coagulating sedimentation tank enters a subsequent working section after passing through a micro-filtration HMF membrane filter;

step three, electrochemical-photocatalysis-ozone synergistic treatment: the effluent of the microfiltration HMF membrane filter enters an electrochemical-photocatalytic-ozone synergistic reactor (shown in figure 1) for treatment for 15 min; the electrochemical-photocatalytic-ozone synergetic reactor is made of toughened glass (3 in figure 1), a visible light source (1 in figure 1) is arranged at the top of the reactor, a photocatalyst filling cavity (4 in figure 1) is arranged along the central shaft of the reactor, the filling cavity is formed by a polytetrafluoroethylene fiber net fixed by a stainless steel framework, an airlift internal circulation structure (7 in figure 1) is arranged below the reactor, an electrolytic anode (6 in figure 1) is arranged outside the circulation structure, an electrolytic cathode (5 in figure 1) is arranged on the outermost side of the circulation structure, the electrolytic anode and the electrolytic cathode are both in a cylinder shape without a bottom and a cover, and an air inlet at the lower end of the reactor is sequentially connected with an air dissolving device (11 in figure 1), an air mixing device (12 in figure 1) and an ozone generator (15 in figure 1); the ozone generator is connected with the oxygen steel cylinder, and the volume ratio of air to ozone is adjusted to 10:1 by controlling the air pump, the oxygen steel cylinder and the ozone generator;

step five, aerating the biological filter: introducing the effluent of the cation exchange column into a biological aerated filter for treatment; the process parameters of the biological aerated filter are as follows: the normal filtration speed is 1.50m/h, the forced filtration speed is 1.75m/h, and three-stage air-water backwashing is adopted;

Further, the preparation method of the modified sepiolite comprises the following steps: firstly, immersing sepiolite fiber into 6mol/L hydrochloric acidSonicating for 20min, calcining at 200 deg.C for 2h, and adding 0.3mol/LAlCl₃Soaking the solution for 6h, and then grafting polyacrylamide to obtain the modified sepiolite.

Further, the preparation method of the organic bentonite gel comprises the following steps: crushing bentonite raw ore to 200 meshes, adding water to prepare a suspension, adding a sodium treatment agent accounting for 3% of the mass of the bentonite, stirring for 30min, separating and purifying, adding water, uniformly mixing, stirring for 2h at 60 ℃, then adding starch accounting for 30% of the mass of the bentonite, stopping heating, continuously stirring to room temperature, adding an acrylic acid solution, sequentially adding a cross-linking agent MBA and an initiator potassium persulfate, reacting for 3h at 70 ℃, soaking the prepared gel with water at room temperature, aging for 16h, and freeze-drying to obtain the bentonite/calcium carbonate gel.

Further, the photocatalyst filler in the third step is glass beads loaded with the zinc-lanthanum doped titanium dioxide nanocrystalline porous membrane; the preparation method comprises the following steps: mixing zinc nitrate, lanthanum nitrate solution and titanium dioxide colloidal solution to obtain co-doped ultrafine particle colloidal solution, then dipping the glass beads in the colloidal solution, and removing the glass beads which are subjected to heat treatment in a nitrogen-filled tube furnace at the temperature of 420 ℃ for 30min to obtain the glass beads loaded with the zinc-lanthanum doped titanium dioxide nanocrystalline porous membrane.

Example 2

step two, coagulating sedimentation: the effluent of the oil removal device enters a coagulating sedimentation tank, a composite flocculant is added into a stirring coagulation area of the coagulating sedimentation tank according to 2.0kg/t, the coagulation reaction is carried out, solid-liquid separation is carried out in the sedimentation area, and the effluent of the coagulating sedimentation tank enters a subsequent working section after passing through a micro-filtration HMF membrane filter;

step three, electrochemical-photocatalysis-ozone synergistic treatment: the effluent of the microfiltration HMF membrane filter enters an electrochemical-photocatalytic-ozone synergistic reactor for treatment for 20 min; the electrochemical-photocatalytic-ozone synergistic reactor is made of toughened glass, a visible light source is arranged at the top of the reactor, a photocatalyst filling cavity is arranged along the central shaft of the reactor and consists of a polytetrafluoroethylene fiber net fixed by a stainless steel framework, an airlift internal circulation structure is arranged below the reactor, an electrolytic anode is arranged outside the circulation structure, an electrolytic cathode is arranged on the outermost side of the circulation structure, the electrolytic anode and the electrolytic cathode are both bottomless and uncovered cylinders, and an air inlet at the lower end of the reactor is sequentially connected with an air dissolving device, an air mixing device and an ozone generator; the ozone generator is connected with the oxygen steel cylinder, and the volume ratio of air to ozone is adjusted to be 20:1 by controlling the air pump, the oxygen steel cylinder and the ozone generator;

step five, aerating the biological filter: introducing the effluent of the cation exchange column into a biological aerated filter for treatment; the process parameters of the biological aerated filter are as follows: the normal filtration speed is 1.51m/h, the forced filtration speed is 1.78m/h, and three-stage gas-water backwashing is adopted;

Further, the preparation method of the modified sepiolite comprises the following steps: firstly, immersing sepiolite fibers into 6mol/L hydrochloric acid for ultrasonic treatment for 30min, then calcining for 3h at the high temperature of 230 ℃, and then using 0.3mol/LAlCl₃Soaking the solution for 9h, and then grafting polyacrylamide to obtain the modified sepiolite.

Further, the preparation method of the organic bentonite gel comprises the following steps: crushing bentonite raw ore to 200 meshes, adding water to prepare a suspension, adding a sodium treatment agent accounting for 3% of the mass of the bentonite, stirring for 30min, separating and purifying, adding water, uniformly mixing, stirring for 2h at 60 ℃, then adding starch accounting for 30% of the mass of the bentonite, stopping heating, continuously stirring to room temperature, adding an acrylic acid solution, sequentially adding a cross-linking agent MBA and an initiator potassium persulfate, reacting for 3h at 70 ℃, soaking the prepared gel with water at room temperature, aging for 20h, and freeze-drying to obtain the bentonite/calcium carbonate gel.

Further, the photocatalyst filler in the third step is glass beads loaded with the zinc-lanthanum doped titanium dioxide nanocrystalline porous membrane; the preparation method comprises the following steps: mixing zinc nitrate, lanthanum nitrate solution and titanium dioxide colloidal solution to obtain co-doped ultrafine particle colloidal solution, then dipping the glass beads in the colloidal solution, and removing the glass beads which are subjected to heat treatment in a nitrogen-filled tube furnace at 460 ℃ for 35min to obtain the glass beads loaded with the zinc-lanthanum doped titanium dioxide nanocrystalline porous membrane.

Example 3

step three, electrochemical-photocatalysis-ozone synergistic treatment: the effluent of the microfiltration HMF membrane filter enters an electrochemical-photocatalytic-ozone synergistic reactor for treatment for 25 min; the electrochemical-photocatalytic-ozone synergistic reactor is made of toughened glass, a visible light source is arranged at the top of the reactor, a photocatalyst filling cavity is arranged along the central shaft of the reactor and consists of a polytetrafluoroethylene fiber net fixed by a stainless steel framework, an airlift internal circulation structure is arranged below the reactor, an electrolytic anode is arranged outside the circulation structure, an electrolytic cathode is arranged on the outermost side of the circulation structure, the electrolytic anode and the electrolytic cathode are both bottomless and uncovered cylinders, and an air inlet at the lower end of the reactor is sequentially connected with an air dissolving device, an air mixing device and an ozone generator; the ozone generator is connected with the oxygen steel cylinder, and the volume ratio of air to ozone is adjusted to be 30:1 by controlling the air pump, the oxygen steel cylinder and the ozone generator;

step five, aerating the biological filter: introducing the effluent of the cation exchange column into a biological aerated filter for treatment; the process parameters of the biological aerated filter are as follows: the normal filtration speed is 1.52m/h, the forced filtration speed is 1.80m/h, and three-stage type air-water backwashing is adopted;

Further, the preparation method of the modified sepiolite comprises the following steps: immersing sepiolite fiber in 6mol/L hydrochloric acid for ultrasonic treatment for 40min, calcining at 250 ℃ for 4h, and then using 0.3mol/LAlCl₃Soaking the solution for 12h, and then grafting polyacrylamide to obtain the modified sepiolite.

Further, the preparation method of the organic bentonite gel comprises the following steps: crushing bentonite raw ore to 200 meshes, adding water to prepare a suspension, adding a sodium treatment agent accounting for 3% of the mass of the bentonite, stirring for 30min, separating and purifying, adding water, uniformly mixing, stirring for 2h at 60 ℃, then adding starch accounting for 30% of the mass of the bentonite, stopping heating, continuously stirring to room temperature, adding an acrylic acid solution, sequentially adding a cross-linking agent MBA and an initiator potassium persulfate, reacting for 3h at 70 ℃, soaking the prepared gel with water at room temperature, aging for 24h, and freeze-drying to obtain the bentonite/calcium carbonate gel.

Further, the photocatalyst filler in the third step is glass beads loaded with the zinc-lanthanum doped titanium dioxide nanocrystalline porous membrane; the preparation method comprises the following steps: mixing zinc nitrate, lanthanum nitrate solution and titanium dioxide colloidal solution to obtain co-doped ultrafine particle colloidal solution, then dipping the glass beads in the colloidal solution, and removing the glass beads which are subjected to heat treatment in a nitrogen-filled tube furnace at 480 ℃ for 40min to obtain the glass beads loaded with the zinc-lanthanum doped titanium dioxide nanocrystalline porous membrane.

Comparative example 1

The process is the same as example 2 except that the composite flocculant in the step two does not contain modified sepiolite, namely the composite flocculant is obtained by mixing organic bentonite gel, a bacillus megaterium SY-Z5 fermentation broth and a bacillus subtilis LSY-ND fermentation broth according to the mass ratio of 1:6: 2.

Comparative example 2

The same as example 2 is carried out except that the composite flocculant in the second step does not contain organobentonite gel, namely the composite flocculant is obtained by mixing modified sepiolite, bacillus megaterium SY-Z5 fermentation liquor and bacillus subtilis LSY-ND fermentation liquor according to the mass ratio of 1:6: 2.

Comparative example 3

The same as example 2 is carried out except that the composite flocculant in the second step does not contain a fermentation broth of Bacillus megaterium SY-Z5 and a fermentation broth of Bacillus subtilis LSY-ND, namely the composite flocculant is obtained by mixing modified sepiolite and organobentonite gel according to a mass ratio of 1: 1.

Comparative example 4

The procedure is as in example 2 except that the composite flocculant in the second step is prepared by mixing modified sepiolite, organic bentonite gel, bacillus megaterium SY-Z5 fermentation liquor and bacillus subtilis LSY-ND fermentation liquor according to the mass ratio of 2:3:6: 2.

Comparative example 5

The same procedure as in example 2 was followed except that the oxygen cylinder and the ozone generator were turned off during the electrochemical-photocatalytic-ozone co-reactor treatment in step three, i.e., only the electrochemical-photocatalytic co-treatment was used.

Comparative example 6

The same procedure as in example 2 was repeated, except that the electrochemical-photocatalytic-ozone co-reactor in step three was not powered on, i.e., only the photocatalytic-ozone co-reactor was used.

Comparative example 7

The same as example 2 is carried out except that no photocatalyst filler is added into the photocatalyst filler cavity during the treatment of the electrochemical-photocatalytic-ozone synergistic reactor in the third step, i.e., only the electrochemical-ozone synergistic treatment is adopted.

The water quality detection results of the effluent water obtained in the above examples 1 to 3 and comparative examples 1 to 7 are shown in the following table 1:

TABLE 1

As can be seen from Table 1, the detection items of the effluent quality of the embodiments 1 to 3 of the invention are far better than the discharge standard of electroplating wastewater in GB21900-2008, and can be directly recycled. The water quality of the effluent of comparative examples 1 to 4 is not as good as that of example 2, which may be caused by excessive residues of suspended matters, organic pollutants and heavy metals in the flocculation precipitation step, so that the subsequent steps are affected, and the results show that the three components of the composite flocculant have synergistic effect in the aspects of pollutant adsorption and flocculation precipitation, and the flocculation effect is closely related to the proportion of the three components. The water quality of the effluent of comparative examples 5-7 is not as good as that of example 2, and the results show that the electrochemical-photocatalytic-ozone synergistic treatment has a better pollutant degradation effect compared with the two synergistic treatments on the premise that the treatment time is the same.

The above description is only for the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and other modifications or equivalent substitutions made by the technical solution of the present invention by the ordinary skilled in the art should be covered within the scope of the claims of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. The advanced treatment method of the electroplating wastewater is characterized by comprising the following steps:

2. The advanced treatment method for the electroplating wastewater according to claim 1, wherein the compound coagulant in the second step is obtained by mixing modified sepiolite, organic bentonite gel, fermentation liquor of bacillus megaterium SY-Z5 and fermentation liquor of bacillus subtilis LSY-ND according to a mass ratio of 1:1:6: 2.

3. The advanced treatment method for the electroplating wastewater as claimed in claim 2, wherein the preparation method of the modified sepiolite comprises the following steps: immersing sepiolite fibers into 6mol/L hydrochloric acid for ultrasonic treatment for 20-40 min, calcining at 200-250 ℃ for 2-4 h, and then using 0.3mol/LAlCl₃Soaking the sepiolite powder in the solution for 6-12 h, and then grafting polyacrylamide to obtain the modified sepiolite.

4. The advanced treatment method for electroplating wastewater according to claim 2, wherein the preparation method for the organobentonite gel comprises the following steps: crushing bentonite raw ore to 200 meshes, adding water to prepare a suspension, adding a sodium treatment agent accounting for 3% of the mass of the bentonite, stirring for 30min, separating and purifying, adding water, uniformly mixing, stirring for 2h at 60 ℃, then adding starch accounting for 30% of the mass of the bentonite, stopping heating, continuously stirring to room temperature, adding an acrylic acid solution, sequentially adding a cross-linking agent MBA and an initiator potassium persulfate, reacting for 3h at 70 ℃, soaking the prepared gel with water at room temperature, aging for 16-24 h, and freeze-drying to obtain the bentonite/calcium carbonate gel.

5. The advanced treatment method for electroplating wastewater according to claim 1, wherein the photocatalyst filler in the third step is glass beads loaded with a zinc lanthanum doped titanium dioxide nanocrystalline porous membrane; the preparation method comprises the following steps: mixing zinc nitrate, lanthanum nitrate solution and titanium dioxide colloidal solution to obtain co-doped ultrafine particle colloidal solution, then dipping the glass beads in the colloidal solution, and removing the glass beads which are subjected to heat treatment in a nitrogen-filled tube furnace at the temperature of 420-480 ℃ for 30-40 min to obtain the glass beads loaded with the zinc-lanthanum doped titanium dioxide nanocrystalline porous membrane.

6. The advanced treatment method for the electroplating wastewater according to claim 1, wherein the electrolytic anode in step three is an ITO glass mesh electrode loaded with a chelating functionalized magnetic graphene composite material; the electrolytic cathode is a titanium net with the surface covered with a carbon film.

7. The deep treatment method of electroplating wastewater according to claim 1, wherein the loading of the magnetic graphene composite material loaded with chelating functionalization on the ITO glass mesh electrode can be realized by a vertical stripping method.

8. The advanced treatment method for the electroplating wastewater as claimed in claim 1, wherein the preparation method of the chelated functionalized magnetic graphene composite material comprises the following steps: synthesizing ferroferric oxide modified graphene in one step by adopting a solvothermal method, and grafting polyethyleneimine and polyaspartic acid onto the ferroferric oxide modified graphene through amidation reaction.

9. The advanced treatment method for electroplating wastewater according to claim 1, wherein the preparation method for the sulfonic acid type aromatic block cation exchange resin in the fourth step comprises the following steps: chloromethylating the aromatic block polymer, then grafting styrene for modification, and then carrying out sulfonation reaction to obtain the product sulfonic acid type cation exchange resin.