Disclosure of Invention
In view of the above, in order to overcome the problems in the prior art, the invention provides a method for efficiently treating high-salt organic wastewater, which can decompose COD and salts in concentrated wastewater simultaneously, after treatment, COD in the high-salt organic wastewater is degraded, the wastewater is separated into fresh water and concentrated water, the fresh water can be directly discharged according to a composite discharge standard, and the concentrated water can be evaporated by a small amount of energy to realize salt recovery.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a method for treating high-salt organic wastewater by electrodialysis comprises the following steps:
s1: uniformly coating a noble metal salt solution on the surface of the ion exchange membrane, and drying;
s2: uniformly coating SnCl2 solution on the surface of the ion exchange membrane obtained in the step S1, and drying;
s3: preparing a chemical plating solution, adding metal salt, a reducing agent, a compounding agent, a surfactant, metal oxide powder and a dispersing agent into water, stirring until the metal salt, the reducing agent, the compounding agent, the surfactant, the metal oxide powder and the dispersing agent are dissolved, and standing until the mixture is stable to obtain the chemical plating solution;
s4: placing the ion exchange membrane obtained in the step S2 in the chemical plating solution obtained in the step S3 for plating, taking out and cleaning, and installing the ion exchange membrane into an electrodialysis device;
s5: adding a flocculating agent into the high-salinity wastewater, standing, and filtering to obtain a filtrate;
s6: and (4) introducing the high-salt organic wastewater obtained in the step (S5) and an oxidant into an electrodialysis device for electrodialysis treatment to obtain salt-containing concentrated water and fresh water.
The invention combines a certain amount of metal catalyst with the ion exchange membrane by treating the surface of the ion exchange membrane. The addition amount of the catalyst can be controlled within a certain range, and the influence on the permeability of the ion exchange membrane is small. Since the electroless plating method can load metal particles onto the surface of a polymer fiber material or the like, the electroless plating method is selected for the loading. Meanwhile, the invention improves the chemical plating method, and adds the nano metal oxide into the chemical plating solution, so that the metal-metal oxide doping is formed in the process of generating the plating film, and the metal-metal oxide composite catalyst is obtained, and the composite catalyst can oxidize COD under the condition of an oxidant, thereby realizing degradation. The ion exchange membrane plated with the catalyst can effectively remove COD deposition on the surface of the ion exchange membrane, so that the coating can work in a higher COD environment. Meanwhile, the flowing high-salinity wastewater has a certain cleaning effect on the surface of the catalyst, so that the surface of the catalyst can realize self cleaning, and the service life of the catalyst is prolonged. Under the synergistic effect of the ion exchange membrane and the catalyst, the concentration of the high-salinity organic wastewater and the removal of COD can be simultaneously completed.
The method couples wet oxidation to an electrodialysis process, integrates a plurality of steps of processes into one step, shortens the process flow, and has the advantages of low energy consumption, small environmental pollution, long service life of the catalyst, low treatment cost and the like.
Further, in the step S1, the noble metal salt solution is PdCl2、RuCl3、H2PtCl6、H3IrCI6、AgNO3The concentration of the noble metal salt solution is 0.001-0.5 mol/L, and the coating amount is 10-100 g/m2. The above conditions and combination thereof are favorable for improving the catalytic effect of the metal-metal oxide composite catalyst formed in the process of generating the coating film, thereby effectively removing COD deposition on the surface of the ion exchange membrane and being favorable for improving the final high-salinity wastewater treatment effect.
Further, in the step S2, the concentration of the SnCl2 solution is 0.1-3 mol/L, and the coating amount is 10-100 g/m2。
Further, in step S3:
the metal salt is NiCl2、CoCl2、CuCl2、SnCl2、MnCl2、CrCl3、AgNO3Preferably NiCl2、CoCl2The concentration of the metal salt is 0.1-5 mol/L, preferably 0.5-2 mol/L;
the reducing agent is NaH2PO2、NaBH4、N2H4·H2One or more of O and formaldehyde, wherein the concentration of the reducing agent is 0.5-20 mol/L;
the compounding agent is triphenylphosphine, sodium pyrophosphate and (NaPO)3)6One or more of diethanolamine, triethanolamine, diethylenetriamine pentacarboxylate, EDTA, polyacrylic acid, citric acid and the like, wherein the concentration of the compounding agent is 0.2-20 mol/L;
the surfactant is one or more of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and n-octyl sodium sulfate, and the concentration of the surfactant is 0.001-0.2 mol/L;
the metal oxide powder is one or more of TiO2, alpha-Al 2O3, gamma-Al 2O3, SiO2, Fe2O3, CuO and MgO, preferably TiO2, the particle size of the metal oxide powder is 20-40000 nm, preferably 50-500 nm, and the adding amount of the metal oxide powder is 10-200 g/L, preferably 20-50 g/L;
the dispersing agent is one or more of methylene dinaphthalene sodium sulfonate, polyacrylamide, sodium polyacrylate, cellulose sodium sulfonate, fatty acid methyl ester sodium sulfonate and the like, and the adding amount of the dispersing agent is 0.01-10 g/L, preferably 0.2-1 g/L. The above conditions and combination thereof are favorable for improving the catalytic effect of the metal-metal oxide composite catalyst formed in the process of generating the coating film, thereby effectively removing COD deposition on the surface of the ion exchange membrane and being favorable for improving the final high-salinity wastewater treatment effect.
Further, in the step S3, all solutes are dissolved in water, stirred until completely dissolved, and left for 2 hours, and then the upper layer stable solution is taken out as the plating solution. The operation is beneficial to smoothly obtaining high-quality plating solution with few impurities, thereby ensuring the normal operation of film plating and smoothly obtaining the composite catalyst.
Further, in the step S4, the anion exchange membrane and the cation exchange membrane are placed in the plating solution obtained in the step S3, the plating temperature is 20 to 40 ℃, the plating time is 10 to 100min, preferably 10 to 15min, and after the chemical plating is completed, the ion exchange membrane is cleaned to be neutral. The operation condition is favorable for ensuring the normal operation of film coating, and the composite catalyst with good catalytic effect is smoothly obtained.
Further, in the step S5, the added flocculating agent is one or more of polyaluminium chloride, polyferric chloride, polyaluminium silicate, activated silicic acid, polyacrylamide and the like, and the adding amount of the flocculating agent is 0.05-1 g/L, preferably 0.1-0.2 g/L; adding a flocculating agent, standing for 0.5h, and filtering the wastewater by quartz sand and/or activated carbon. Step S5 realizes the preliminary impurity removal of the wastewater, especially the removal of larger particles of impurities, and the above conditions can improve the impurity removal effect of the wastewater.
Further, in the step S6, an electrodialysis apparatus is used to operate at a voltage of 20 to 100V, preferably 25 to 50V, and the introduced oxidant is one or more of air, oxygen, ozone, and hydrogen peroxide. And the electrodialysis treatment is carried out under the voltage condition, so that the electrodialysis treatment of the wastewater is more efficient.
Further, in step S3, the metal oxide powder is a nano metal oxide powder.
The method for treating the high-salinity organic wastewater by electrodialysis has the following advantages:
(1) the method for treating the high-salinity organic wastewater provided by the invention can realize the concentration of the high-salinity wastewater and the removal of COD in the high-salinity wastewater in one step, has the characteristics of simple process flow, short treatment time, wide treatment range, low equipment investment, no secondary pollution and the like, and can efficiently treat the high-salinity organic wastewater.
(2) The method for treating the high-salinity organic wastewater provided by the invention has the advantages of low energy consumption and high COD removal rate;
(3) the metal-metal oxide composite catalyst obtained by the method has long service life, can work for a long time without replacement, and saves resources and cost;
(4) the treatment method has simple steps, is easy for industrial amplification and has good application prospect.
Detailed Description
The invention will be described in detail with reference to specific embodiments. The examples are intended to illustrate the invention, but are not intended to limit the scope of applicability of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The composition of the wastewater treated in the following examples is shown in Table 1.
Example 1
In the embodiment of the invention, the method for treating the high-salinity organic wastewater comprises the following specific steps:
(1) uniformly coating 0.02mol/L RuCl on the surface of the ion exchange membrane3Solution, coating weight 20g/m2Drying the ion exchange membrane for later use after coating;
(2) coating 0.5mol/L SnCl on the surface of the ion exchange membrane obtained in the step (1)2Solution, coating weight 10g/m2Drying the ion exchange membrane for later use after coating;
(3) preparing chemical plating solution with NiCl as the component21mol/L，NaH2PO24mol/L, 0.5mol/L triethanolamine, 0.1mol/L sodium dodecyl benzene sulfonate and 0.2g/L sodium polyacrylate with the titanium oxide powder of 100nm particle size, completely dissolving the components in water, stirring to be uniform, standing for 0.5h, and taking the upper liquid as a plating solution;
(4) placing the ion exchange membrane obtained in the step (2) in a plating solution for 10min, removing the ion exchange membrane, cleaning the ion exchange membrane, and installing the ion exchange membrane into an electrodialysis device;
(5) collecting wastewater of a certain chemical plant, wherein the main components of the wastewater are shown in Table 1, adding 0.2g/L of polyacrylamide serving as a flocculating agent into the wastewater, standing for 0.5h, and filtering by using quartz sand and activated carbon;
(6) and (3) introducing the wastewater obtained in the step (5) into an electrodialysis device for treatment, selecting oxygen as an oxidant, introducing the oxygen at 2000L/h, and detecting the operation parameters and the water quality of the electrodialysis device every 10 minutes, wherein the results are shown in Table 2.
Example 2
In the embodiment of the invention, the method for treating the high-salinity organic wastewater comprises the following specific steps:
(1) uniformly coating 0.01mol/L H on the surface of the ion exchange membrane2PtCI6Solution, coating weight 10g/m2Drying the ion exchange membrane for later use after coating;
(2) coating 0.5mol/L SnCl on the surface of the ion exchange membrane obtained in the step (1)2Solution, coating weight 10g/m2Drying the ion exchange membrane for later use after coating;
(3) preparing chemical plating solution with CuCl as the component22mol/L, 4mol/L hydrazine hydrate, 0.5mol/L ammonia water, 0.1mol/L sodium dodecyl benzene sulfonate, 100g/L silicon oxide powder with the particle size of 50nm and 0.2g/L sodium cellulose sulfonate, completely dissolving the components in water, stirring to be uniform, standing for 0.5h, and taking the upper layer liquid as a plating solution;
(4) placing the ion exchange membrane obtained in the step (2) in a plating solution for 5min, removing the ion exchange membrane, cleaning the ion exchange membrane, and installing the ion exchange membrane into an electrodialysis device;
(5) using the wastewater used in example 1, adding 1g/L flocculant polyaluminium chloride into the wastewater, standing for 0.5h, and filtering by using quartz sand and activated carbon;
(6) and (3) introducing the wastewater obtained in the step (5) into an electrodialysis device for treatment, selecting hydrogen peroxide as an oxidant, introducing the hydrogen peroxide into the electrodialysis device at an amount of 200g/h, and detecting the operation parameters and the water quality of the electrodialysis device every 10 minutes, wherein the results are shown in Table 3.
TABLE 1 composition of wastewater
Table 2 example 1 results of wastewater treatment
Table 3 example 2 results of wastewater treatment
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.