Method for performing advanced treatment on difficultly-degradable pollutants by using conductive filter membrane-heterogeneous Fenton-like water treatment device
Technical Field
The invention relates to a method for deeply treating difficultly degraded pollutants by using a conductive filter membrane-heterogeneous Fenton-like water treatment device, belonging to the technical field of wastewater treatment.
Background
The advanced treatment of pollutants difficult to degrade in wastewater has been a difficult problem in the environmental protection industry. In order to improve the treatment effect of the pollutants difficult to degrade, the development of novel water treatment equipment, materials and processes becomes a hotspot of the environmental protection industry.
In the existing industrial wastewater treatment process, a biochemical process is an important stage for removing organic pollutants in wastewater, but the removal effect of the stage on the organic pollutants difficult to biodegrade is very little, so that the key point for improving the effluent quality of the industrial wastewater lies in the removal of the organic pollutants difficult to degrade. The existing removal process of the pollutants difficult to degrade has various types, such as coagulating sedimentation, activated carbon adsorption, membrane separation and the like, although the processes can remove the organic pollutants difficult to degrade in the industrial wastewater to a certain degree, secondary pollution can be generated, such as sludge and inactivated activated carbon formed by using a large amount of medicaments; or high construction and operation costs, such as membrane module replacement and maintenance, etc.
The advanced oxidation technology is a novel advanced wastewater treatment technology, and utilizes free radicals (such as hydroxyl free radical. OH) which have strong oxidizing property and no selectivity and are generated under different conditions to oxidize and degrade refractory organic matters in wastewater to easily biodegradable micromolecule organic matters or CO2And water. Common advanced oxidation treatment technologies include fenton oxidation, ozone catalytic oxidation, ultraviolet light catalytic process, and the like. However, the treatment efficiency of the existing process is limited and the cost is high, for example, Fenton oxidation consumes a large amount of medicaments and generates iron-containing sludge, ozone catalytic oxidation has the problems of tail gas treatment, safety, catalyst inactivation and the like, and the conventional ultraviolet light catalytic process has low light energy utilization rate and the like. Therefore, how to make best use of the advantages and avoid the disadvantages and how to construct an efficient advanced oxidation system is the key point of research on the advanced treatment of industrial wastewater.
The membrane separation technology is a typical advanced treatment technology, and has been widely applied in the field of advanced wastewater treatment due to the advantages of good water treatment effect, stable effluent quality, simple and convenient operation, easy equipment integration and the like. However, membrane fouling due to rejection, the tradeoff between membrane permeability and selectivity, and subsequent handling of the concentrate, limit further application of membrane separation techniques. In recent years, the conductive film technology becomes an emerging research direction in the field of water treatment, the conductive film can simultaneously realize the size interception and electrochemical degradation of pollutants, and the existence of an external voltage can inhibit the deposition and enrichment of the pollutants on the film by regulating the interaction force between the pollutants and a film working electrode.
Therefore, the method has the advantages of inhibiting the deposition and enrichment of pollutants on the membrane, reducing the use of catalytic agents of the advanced oxidation process and the discharge of metal ions such as iron, manganese and the like, improving the Fenton-like treatment efficiency, shortening the water treatment process and improving the water treatment effect of the difficultly-degraded pollutants, and has important significance for the advanced treatment of wastewater and good application prospect.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for deeply treating refractory pollutants by using a conductive filter membrane-heterogeneous Fenton-like water treatment device.
The treatment method of the invention can inhibit the deposition and enrichment of pollutants on the membrane, reduce the use of catalytic agents of advanced oxidation process and the discharge of metal ions such as iron, manganese and the like, improve the Fenton-like treatment efficiency, shorten the water treatment flow and improve the water treatment effect of the pollutants difficult to degrade.
In order to realize the purpose, the invention is realized by the following technical scheme:
a method for carrying out advanced treatment on difficultly-degraded pollutants by utilizing a conductive filter membrane-heterogeneous Fenton-like water treatment device,
the device for treating the heterogeneous Fenton-like water by the conductive filter membrane is coupled with the conductive filter membrane and the heterogeneous Fenton-like water into a whole and comprises a reactor body, wherein a water inlet is formed in one side of the reactor body, a water outlet is formed in the side wall of the reactor body, the water outlet is connected with a water outlet pipe, the conductive filter membranes which are longitudinally and equally arranged are arranged in the reactor body, high-grade oxidation catalytic fillers are filled among the conductive filter membranes, a plate electrode is longitudinally arranged between the conductive filter membrane close to the water inlet and the water inlet, the plate electrode is an anode, the plate electrode is externally connected with a direct-current power supply anode through a lead, the conductive filter membrane is a cathode, and the plate electrode is externally connected with a direct-current power supply cathode through a lead;
the deep processing method comprises the following steps:
1) the electrode plate and the conductive filter membrane are externally connected with low-voltage direct current, the voltage of an external electric field is 0.5-10V, and the wastewater is mixed with a high-grade oxidation agent and then is injected into the conductive filter membrane-heterogeneous Fenton-like water treatment device through a water inlet by a constant flow pump;
2) pollutants in the advanced oxidation agent and the wastewater are rapidly diffused to the surfaces and inner holes of the filler and the conductive filter membrane, and are rapidly catalyzed and decomposed into strong oxidant OH free radicals under the action of an external electric field, so that an electric field enhanced heterogeneous Fenton-like reaction is formed, and the refractory organic pollutants on the surface of the wastewater neutralization membrane are oxidized and degraded;
3) the organic pollutants which are difficult to degrade in the wastewater are removed through membrane interception and filtration and heterogeneous Fenton-like oxidation degradation, and the treated water is discharged from a water outlet.
According to the invention, the material of the reactor body is preferably organic glass, stainless steel or carbon steel, the cross section is square or round, and the hydraulic retention time is 2-120 minutes.
According to the invention, the conductive filter membrane is preferably a conductive nanofiltration membrane, a conductive microfiltration membrane or a conductive ceramic membrane loaded with carbon nanotubes, graphene or carbon black materials, and the interception aperture of the conductive filter membrane is 1nm-1 μm.
Preferably, according to the invention, the distance between the conducting filter membranes is 5-50 cm.
Most preferably, the distance between the conducting filter membranes is 10 cm.
According to the invention, the electrode plate is preferably a titanium plate, a titanium mesh, a stainless steel plate, a stainless steel mesh, Ti/Sb-SnO2Electrode plate or Ti/PbO2And an electrode plate.
According to the invention, the bottom of the reactor body is preferably provided with aeration heads, the distance between the aeration heads is 5-50cm, the aeration gas is air or oxygen, and the aeration intensity is 5-25m3/m2·h。
According to the invention, the advanced oxidation catalytic filler is a matrix material loaded with metal or metal oxide, the metal is iron, manganese, nickel, copper, cobalt, platinum, silver or palladium, and the matrix material is activated carbon, biochar, nanocarbon or three-dimensional graphene.
According to the invention, the preferred higher oxidizing agent is hydrogen peroxide, persulfate or hypochlorite, and the dosage of the higher oxidizing agent enables the concentration to reach 1-100 mM; further preferably, the higher oxidizing agent is used in an amount to achieve a concentration of 10-30 mM.
The supporting method of the matrix material loaded with the metal or the metal oxide is prepared according to the prior art.
The advanced treatment method of the invention takes a conductive filter membrane and a heterogeneous Fenton-like water treatment device as a core, utilizes an electrode plate as an anode and a conductive filter membrane as a cathode, and fills carbon materials with catalytic performance between the conductive filter membranes to form a coupling system of the conductive filter membrane and the heterogeneous Fenton. The water inlet of the water treatment device is arranged on one side of the anode plate, and the water outlet of the water treatment device is arranged on one side of the cathode filter membrane. The high-grade oxidation agent is quickly catalytically decomposed on the catalytic filler and the conductive filter membrane into a strong oxidant OH free radical to oxidize and degrade the organic pollutants which are difficult to degrade on the surface of the membrane and in the inlet water. The pollutants in the inlet water are removed through heterogeneous Fenton oxidation and membrane interception and filtration, and are discharged from the water outlet. In particular, if no higher oxidizing agent is added, the oxygen provided by aeration can be reduced to H in situ on the catalytic filler and the conductive filter membrane2O2And the function of removing pollutants through oxidation is achieved.
The invention has the technical characteristics and advantages that:
the advanced treatment method combines the conductive filter membrane with the heterogeneous Fenton-like oxidation method, takes the electrode plate as the anode and the conductive filter membrane as the cathode, and fills carbon materials with catalytic performance between the conductive filter membranes, and the reactor can synchronously complete the Fenton-like reaction and the membrane filtration, greatly shortens the water treatment process and improves the water treatment effect.
2. The treatment method is carried out by utilizing the conductive filter membrane-heterogeneous Fenton-like water treatment device, the high-grade oxidation medicament is rapidly catalyzed and decomposed into strong oxidant OH free radicals on the catalytic filler and the conductive filter membrane to form an electric field to strengthen the heterogeneous Fenton-like reaction, and the wastewater can be oxidized and degradedOf (a). In addition, the oxygenation aeration can be reduced into H in situ on the catalytic filler and the conductive filter membrane2O2The catalyst also has the functions of homogenizing and mixing, so that the catalytic filler is uniformly distributed in the reactor, and the mass transfer rate and the treatment efficiency of the device are obviously improved.
3. The method of the invention realizes two functions of membrane filtration and Fenton-like oxidation simultaneously in one water treatment unit. The principle of the device is that a conductive film is used as an electrode of the device, a carbon material with catalytic efficiency and conductivity is loaded on the conductive film, the catalytic generation of free radicals such as hydroxyl free radicals, oxygen free radicals, chlorine free radicals, sulfate free radicals and the like is realized on the surface of the film through electrochemical reaction, the contact reaction efficiency of pollutants and the hydroxyl free radicals in the wastewater is improved by utilizing the process that the wastewater passes through film holes, and the purposes of quickly degrading the pollutants and improving the water treatment efficiency are achieved by combining the physical interception of the film. In addition, in order to improve the efficiency of the Fenton-like treatment, the equipment can be filled with advanced oxidation catalytic filler.
Drawings
FIG. 1 is a schematic view of a conducting membrane-heterogeneous Fenton-like water treatment device;
in the figure, the device comprises a reactor body 1, a reactor body 2, a water inlet 3, an electrode plate 4, a water outlet pipe 5, a conductive filter membrane 6, a lead 7, a high-grade oxidation catalytic filler 8, an aeration head 9, a lead 10, a water outlet pump 11 and a mixing device.
FIG. 2 is a graph showing the removal rate of rhodamine B in application example 1.
FIG. 3 is a graph showing the decolorization effect of rhodamine B in application example 1.
FIG. 4 is a graph of the removal rate of tetracycline by application example 2.
FIG. 5 is a plot of HPLC peak areas before (a) and after (b) tetracycline removal using example 2.
Detailed Description
The invention will be further explained with reference to the drawings and examples.
Example 1
A method for carrying out advanced treatment on difficultly-degraded pollutants by utilizing a conductive filter membrane-heterogeneous Fenton-like water treatment device,
the conductive filter membrane-heterogeneous Fenton-like water treatment device is coupled with a conductive filter membrane and heterogeneous Fenton-like water into a whole, and has a structure shown in figure 1, and comprises a reactor body 1, wherein the reactor body 1 is a cuboid with the size of 50cm multiplied by 30cm multiplied by 10cm, a water inlet 2 is arranged on one side of the reactor body, a water outlet is arranged on the side wall of the reactor body, conductive filter membranes 5 which are longitudinally and equally arranged are arranged inside the reactor body, the size of each conductive filter membrane 5 is 25cm multiplied by 8cm, the membrane aperture is 0.8um, the distance between every two conductive filter membranes 5 is 3cm, each conductive filter membrane is a conductive nanofiltration membrane loaded with carbon nanotubes, advanced oxidation catalytic fillers 7 are filled between every two conductive filter membranes, the advanced oxidation catalytic fillers 7 are biological carbon loaded with ferromanganese, an electrode plate 3 is longitudinally arranged between the conductive filter membrane close to the water inlet 2 and the water inlet 2, and the electrode plate 3 is an anode, the electrode plate 3 is a titanium mesh and is externally connected with a direct current power supply anode through a lead, the conductive filter membrane 5 is a cathode, and is externally connected with a direct current power supply cathode through a lead; the bottom of the reactor body 1 is provided with an oxygen aeration head 8 with aeration quantity of 10m3/m2H, the distance between the aeration heads is 25cm, and the aeration gas is air. The water outlet is connected with a water outlet pipe 4 in a converging manner, and a water outlet pump 10 is arranged on the water outlet pipe 4.
The deep processing method comprises the following steps:
1) the electrode plate and the conductive filter membrane are externally connected with low-voltage direct current, the voltage of an external electric field is 3V, and the wastewater is mixed with 10% potassium persulfate solution and then is injected into the conductive filter membrane-heterogeneous Fenton-like water treatment device through a water inlet 2 by a constant flow pump; the flow rate is 20L/h, the concentration of the potassium persulfate after mixing is 10mg/L,
2) potassium persulfate and pollutants in the wastewater rapidly diffuse into the surfaces and internal holes of the filler and the conductive filter membrane, and under the action of an external electric field, the potassium persulfate catalyzes the surfaces of the iron-manganese-loaded biochar advanced oxidation catalytic filler 7 and the conductive ultrafiltration membrane 5 to generate sulfate radicals and hydroxyl radicals so as to form an electric field reinforced heterogeneous Fenton-like reaction and oxidize and degrade refractory organic pollutants on the surface of the wastewater neutralization membrane;
3) the organic pollutants which are difficult to degrade in the wastewater are removed through membrane interception and filtration and heterogeneous Fenton-like oxidation degradation, and the treated water is discharged from a water outlet.
Application Experimental example 1
The method of example 1 is adopted to treat the simulated rhodamine B dye wastewater,
when the device operates, the voltage applied by low-voltage direct current is 3V, 10% potassium persulfate solution is added into rhodamine B dye wastewater through a mixing device 11, the concentration of the mixed potassium persulfate is 10mg/L, then the rhodamine B wastewater mixed with the potassium persulfate is injected from a bottom water inlet 2 of a reactor 1 by using a constant flow pump, the flow rate is 20L/h, and the potassium persulfate generates sulfate radicals and hydroxyl radicals in the surface catalysis of a biological carbon advanced oxidation catalysis filler 7 loaded with iron and manganese and a conductive ultrafiltration membrane 5 so as to oxidize and decompose organic pollutants in the wastewater. Then, filtering by a membrane, and completely decoloring the rhodamine B dye simulated wastewater; the removal rate and the decoloring effect of rhodamine B are shown in FIGS. 2 and 3.
The specific water inlet and outlet indexes are as follows, the COD of inlet water is 10.2mg/L, the absorbance at 554nm is 0.403, the absorbance of outlet water can be reduced to 0.033 after the device runs for 5min, and the COD can be reduced to 7.8 mg/L.
Example 2
A method for carrying out advanced treatment on refractory pollutants by utilizing a conductive filter membrane-heterogeneous Fenton-like water treatment device, wherein the water treatment device is the same as that in the embodiment 1; the difference lies in that:
the deep processing method comprises the following steps:
1) the electrode plate and the conductive filter membrane are externally connected with low-voltage direct current, the voltage of an external electric field is 5V, and the wastewater is mixed with 10% potassium persulfate solution and then is injected into the conductive filter membrane-heterogeneous Fenton-like water treatment device through a water inlet 2 by a constant flow pump; the flow rate is 15L/h, the concentration of the potassium persulfate after mixing is 20mg/L,
2) potassium persulfate and pollutants in the wastewater rapidly diffuse into the surfaces and internal holes of the filler and the conductive filter membrane, and under the action of an external electric field, the potassium persulfate catalyzes the surfaces of the iron-manganese-loaded biochar advanced oxidation catalytic filler 7 and the conductive ultrafiltration membrane 5 to generate sulfate radicals and hydroxyl radicals so as to form an electric field reinforced heterogeneous Fenton-like reaction and oxidize and degrade refractory organic pollutants on the surface of the wastewater neutralization membrane;
3) the organic pollutants which are difficult to degrade in the wastewater are removed through membrane interception and filtration and heterogeneous Fenton-like oxidation degradation, and the treated water is discharged from a water outlet.
Application Experimental example 2
The method of example 2 was used to treat the simulated tetracycline wastewater,
when the device operates, the low-voltage direct current applied voltage is 5V, 10% potassium persulfate solution is added into the tetracycline wastewater through the mixing device 11, the concentration of the mixed potassium persulfate is 20mg/L, then the tetracycline wastewater mixed with the potassium persulfate is injected from the bottom water inlet 2 of the reactor by using a constant flow pump, and the flow rate is 15L/h. The potassium persulfate is catalyzed on the surfaces of the biological carbon advanced oxidation catalytic filler loaded with iron and manganese and the conductive ultrafiltration membrane to generate sulfate radicals and hydroxyl radicals so as to oxidize and decompose tetracycline in the wastewater. Then, the removal efficiency of tetracycline in the wastewater can reach 99.3 percent through membrane filtration. The tetracycline removal effect is shown in fig. 4 and 5.
The specific water inlet and outlet indexes are as follows, the COD of inlet water is 230.4mg/L, the tetracycline concentration is 200mg/L, and after the device runs for 5min, the COD of outlet water can be reduced to 196.2mg/L, and the tetracycline concentration can be reduced to 13.02 mg/L.
Example 3
The method for performing advanced treatment on refractory pollutants by using the conductive filter membrane-heterogeneous Fenton-like water treatment device is the same as that in the embodiment 1, and is different from the method in that:
the conductive filter membrane is a conductive microfiltration membrane loaded with carbon black materials, the interception aperture is 1nm, and the distance between the conductive filter membranes is 10 cm.
The electrode plate is a titanium plate.
The distance between the aeration heads is 30cm, the aeration gas is air, and the aeration intensity is 20m3/m2·h。
The other was carried out as in example 1.
Example 4
The method for carrying out advanced treatment on the pollutants difficult to degrade by utilizing the conductive filter membrane-heterogeneous Fenton-like water treatment device is the same as that in the embodiment 1,
the difference lies in that:
the deep processing method comprises the following steps:
1) the electrode plate and the conductive filter membrane are externally connected with low-voltage direct current, the voltage of an external electric field is 8V, and the wastewater is mixed with 10% potassium persulfate solution and then is injected into the conductive filter membrane-heterogeneous Fenton-like water treatment device through a water inlet 2 by a constant flow pump; the flow rate is 20L/h, the hydraulic retention time is 60 minutes, the concentration of the potassium persulfate after mixing is 20mg/L,
2) potassium persulfate and pollutants in the wastewater rapidly diffuse into the surfaces and internal holes of the filler and the conductive filter membrane, and under the action of an external electric field, the potassium persulfate catalyzes the surfaces of the iron-manganese-loaded biochar advanced oxidation catalytic filler 7 and the conductive ultrafiltration membrane 5 to generate sulfate radicals and hydroxyl radicals so as to form an electric field reinforced heterogeneous Fenton-like reaction and oxidize and degrade refractory organic pollutants on the surface of the wastewater neutralization membrane;
3) the organic pollutants which are difficult to degrade in the wastewater are removed through membrane interception and filtration and heterogeneous Fenton-like oxidation degradation, and the treated water is discharged from a water outlet.