Method for treating organic phosphine wastewater by homogeneous catalytic wet oxidation

Abstract

The present invention discloses a method for treating organic phosphine wastewater by using homogeneous catalytic wet oxidation, which includes a wet oxidation section, a biochemical treatment section and a phosphorus recovery section; the organic phosphine wastewater, the homogeneous catalyst and the mother liquor of the single membrane electrodialysis are mixed and heated by heat exchange, and then the wet oxidation treatment is carried out, and then the acid adjustment tank is entered after cooling, and then nanofiltration is carried out, the nanofiltration concentrated water enters the single membrane electrodialysis treatment, the single membrane electrodialysis mother liquor is returned to the regulating tank, the anion liquid enters the phosphorus recovery section, and the nanofiltration produced water enters the biochemical treatment section; the biochemical treatment section includes an alkali adjustment tank, a biochemical unit and an effluent monitoring tank in sequence, and the phosphorus recovery section includes a reaction tank and a concentration crystallization unit, and finally forms a product struvite. In view of the characteristics of high COD, high organic phosphorus, high toxicity and difficult degradation of organic phosphine wastewater, the present invention adopts a treatment process with homogeneous catalytic wet oxidation as the core, giving full play to the characteristics of high catalytic activity and strong treatment capacity of homogeneous catalytic wet oxidation, and finally achieving the standard discharge of organic phosphine wastewater.

Description

Technical Field

[0001] The invention relates to a method for treating organic phosphine wastewater, in particular to a method for treating organic phosphine wastewater by utilizing homogeneous catalytic wet oxidation, and belongs to the technical field of wastewater treatment. Background Art

[0002] A large amount of organic phosphine wastewater is generated during the production and use of organic phosphine chelating agents, organic phosphine pesticides, organic phosphine scale and corrosion inhibitors, etc. For example, organic phosphine chelating agents such as ATMP (amino trimethylene phosphonic acid), HEDP (hydroxyethylidene diphosphonic acid), ethylenediamine tetra (methylene phosphonic acid) (EDTMP) have the common characteristics of stable chemical properties, difficult biodegradation, rich in phosphorus and nitrogen, and most of them exist in the form of organic matter; for example, organic phosphine pesticides are mostly phosphates or thiophosphates, and the wastewater they produce contains a large amount of organic phosphine intermediates and hydrolysis products, which are highly toxic, have many difficult-to-degrade substances, and have poor biodegradability. In the absence of other organic wastewater mixing or dilution, it is difficult to directly use biochemical methods to treat them.

[0003] The above-mentioned organic phosphine wastewater must be pretreated before biochemical treatment, and advanced oxidation is a commonly used pretreatment method, which can convert difficult-to-degrade, highly toxic macromolecular organic matter into degradable, low-toxic small-molecule organic matter or even inorganic matter. Commonly used advanced oxidation methods include ozone catalytic oxidation, electrocatalytic oxidation, photocatalysis, Fenton oxidation, wet oxidation, etc. Among them, electrocatalytic oxidation and photocatalysis are still limited by high treatment costs and are difficult to apply industrially. Fenton oxidation has problems such as complex operation, unstable hydrogen peroxide, and loss of iron ions. With the country's control of ozone pollutants, the application of ozone catalytic oxidation is also limited, and its treatment cost is also high.

[0004] Wet oxidation refers to the use of gaseous oxygen as an oxidant under high temperature (120-320°C) and high pressure (0.5-20MPa) conditions to oxidize and decompose organic matter in water into small molecular organic or inorganic matter. It has the characteristics of no secondary pollution and low treatment cost. Drawing on its wide application in alkaline slag wastewater, more and more scholars have begun to study wet oxidation technology to treat other difficult wastewaters. In order to improve its treatment effect and reduce its reaction temperature and pressure, the research focus is on catalytic wet oxidation.

[0005] CN201510274988.5 discloses a catalyst for catalytic wet oxidation of difficult-to-degrade organic wastewater, which is a "precious metal-transition metal-rare earth" composite catalyst, and the main component of the carrier FSC is aluminum oxide; CN201410340574.3 discloses a catalyst for catalytic wet oxidation treatment and a preparation method thereof, which has precious metal-non-precious metal nanoalloy as an active ingredient and activated carbon as a carrier; CN201510661575.2 discloses a multiphase wet oxidation catalyst, the components of which include a composite oxide carrier and a small amount of precious metal; CN201310621017.4 discloses a method for preparing a catalytic wet oxidation catalyst carrier, which has activated carbon as a core and amorphous silicon aluminum as a shell; CN201610911047.2 discloses a catalytic wet oxidation method for degrading organic phosphorus compounds in pesticide wastewater, which uses a metal oxide catalyst supported on a sponge titanium substrate resistant to acid and alkali corrosion.

[0006] The above patents all use heterogeneous catalytic wet oxidation, which has advantages in catalyst separation and recovery and metal loss, but is not necessarily applicable to wet oxidation processes. The paper "Industrial Application of Alkali Slag Moderated Wet Oxidation + SBR Treatment Technology" (2011) discloses the alkali slag moderated wet oxidation process of Fushun Petrochemical Research Institute. This process has been promoted and applied in 28 refining and chemical companies and is highly representative. The wet oxidation reactor used is a bubbling flow internal circulation reactor with an inner cylinder. If a heterogeneous catalyst is used in this reactor, its gas-liquid circulation will be seriously affected, and even the reactor and pipeline will be blocked. If a fixed bed method is used, it will bring greater gas resistance, which is more unfavorable for gas-liquid circulation, and the reaction rate will also be greatly reduced.

[0007] Homogeneous catalysis has no internal and external diffusion effect and high dispersion, so its catalytic efficiency is higher than heterogeneous catalysis, and the catalyst preparation is much simpler than heterogeneous catalyst. However, the biggest problem of homogeneous catalysis in wet oxidation is the loss of metal catalyst. At present, there are few studies in this direction. CN201210225873.3 provides a method for treating industrial wastewater by homogeneous catalytic wet oxidation, in which a ring gear filler is placed in a fixed bed reactor, and the homogeneous catalyst uses an iron-based catalyst, but the patent does not mention the loss of catalyst and the corresponding solution; CN201210350157.8 provides a catalytic wet oxidation pretreatment method for glyphosate production wastewater, in which a multi-component homogeneous catalyst is added, and the catalyst is a soluble transition metal mixed salt. The patent does not mention the problem of catalyst loss and the treatment of organic phosphorus. Summary of the invention

[0008] In view of the above shortcomings, the present invention provides a method for treating organic phosphine wastewater by utilizing homogeneous catalytic wet oxidation for the prior art. By combining homogeneous catalytic wet oxidation with membrane technology, efficient treatment, standard discharge and resource recycling of organic phosphine wastewater are achieved, and the difficult problems of high COD, high organic phosphine, high toxicity and difficulty in degradation of organic phosphine wastewater are solved. At the same time, the problem of catalyst loss in the homogeneous catalytic process is solved, so that the catalyst can be recycled.

[0009] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for treating organic phosphine wastewater by homogeneous catalytic wet oxidation, comprising a wet oxidation section, a biochemical treatment section and a phosphorus recovery section;

[0011] The wet oxidation section includes a regulating tank, a heat exchange unit, a wet oxidation reactor, a cooler, an acid adjustment tank, nanofiltration and single membrane electrodialysis; the organic phosphine wastewater, the homogeneous catalyst and the mother liquor of the single membrane electrodialysis are mixed in the regulating tank and then enter the heat exchange unit, and heat exchange and temperature increase with the effluent of the wet oxidation reactor, and then enter the wet oxidation reactor; the effluent of the wet oxidation reactor is heat exchanged by the heat exchange unit and then cooled by the cooler, and then enters the acid adjustment tank, the effluent of the acid adjustment tank enters the nanofiltration, the concentrated water of the nanofiltration enters the single membrane electrodialysis treatment, the single membrane electrodialysis mother liquor is returned to the regulating tank, the anion liquid enters the phosphorus recovery section, and the nanofiltration produced water enters the biochemical treatment section;

[0012] The biochemical treatment section includes an alkali adjustment tank, a biochemical unit and an effluent monitoring tank in sequence; the biochemical unit adopts an A / O and post-denitrification combined process, and is discharged to the effluent monitoring tank after the treatment is completed, and finally meets the discharge standards;

[0013] The phosphorus recovery section includes a reaction tank and a concentration crystallization unit. The reaction tank produces magnesium ammonium phosphate precipitate by adding magnesium chloride, ammonia and phosphate. The precipitate is sent to the concentration crystallization unit to finally form the product struvite; the supernatant is sent to the alkali adjustment tank.

[0014] Furthermore, the heat exchange unit is composed of multiple heat exchangers, which perform heat exchange on the outlet water of the wet oxidation reactor and the outlet water of the regulating tank. The outlet water of the wet oxidation reactor goes through the tube side, and the outlet water of the regulating tank goes through the shell side. After multiple heat exchanges, the outlet water temperature of the regulating tank rises to 130-160°C, and the outlet water temperature of the wet oxidation reactor decreases to 50-75°C.

[0015] Furthermore, the homogeneous catalyst is a composite catalyst of precious metals and transition metals; the precious metal is selected from one or more of platinum, palladium, rhodium, silver and ruthenium, and the transition metal is selected from one or more of copper, iron, manganese, zinc and nickel, preferably a palladium-copper or palladium-iron composite catalyst, wherein the mass percentage of precious metals in the homogeneous catalyst is 1% to 20%; the precious metals and transition metals exist in the form of metal salt compounds or complexes and are dissolved in the liquid phase.

[0016] Furthermore, the homogeneous catalyst is only added in large quantities when the device is started up, and is added according to the COD mass concentration and metal ion mass concentration ratio of 2000:1 to 2:1. During normal operation, it is appropriately supplemented according to the catalyst loss rate and the change in reaction liquid concentration.

[0017] Furthermore, the wet oxidation reactor is a bubbling flow inner circulation reactor in an inner cylinder, which uses gaseous oxygen (air) as an oxidant under high temperature and high pressure conditions to oxidize general organic matter in water into small molecular organic matter or inorganic matter; those skilled in the art should understand that organic phosphine is an organic matter that is difficult to degrade, and the removal capacity of organic phosphine by wet oxidation alone is limited, but under the conditions of a catalyst, oxygen under high temperature and high pressure is more likely to undergo free radical reactions, and the decomposition and conversion capacity and reaction rate of organic phosphine are greatly improved under the action of the strong oxidizing property of free radicals. On the other hand, homogeneous catalysts themselves have high activity and high selectivity, and their treatment of special pollutants is faster and more effective, and their easy loss problem is also solved by membrane technology.

[0018] Furthermore, the reaction temperature of the wet oxidation reactor is 150-300°C, the reaction pressure is 2MPa-10MPa, and the liquid space velocity is 0.25-4h -1 , the gas-liquid volume ratio is 20:1~500:1.

[0019] Furthermore, the cooling medium of the cooler is circulating water, which further cools the outlet water of the wet oxidation reactor to 30-50°C, meeting the temperature requirements of the subsequent nanofiltration membrane.

[0020] Furthermore, in the acid adjustment tank, the pH is adjusted to 3-6 by adding hydrochloric acid or sulfuric acid, preferably hydrochloric acid.

[0021] Furthermore, the nanofiltration water production rate is 60% to 85%, and the membrane pore size is between 1 and 3 nm. It can intercept the metals of the homogeneous catalyst, high-valent salts (such as phosphates, sulfates, carbonates), unreacted organic phosphorus and other macromolecular organic matter (relative molecular mass greater than 200), etc., and enter the concentrated water side after interception, wherein the metals of the homogeneous catalyst are refluxed to the regulating tank, and after heat exchange and temperature increase, they are returned to the wet oxidation reactor for recycling; the nanofiltration water production includes small molecular organic matter, monovalent salts and ammonia nitrogen, etc.

[0022] Furthermore, the single membrane electrodialysis only uses an anion membrane. Under the action of the electrode drive and the anion membrane, some high-valent anion salts such as phosphate, sulfate, carbonate, etc. in the nanofiltration concentrated water pass through the anion membrane into the concentrated water side, and also include small molecular organic matter that is negative. The cationic catalyst remains in the mother liquor and is reused again; those skilled in the art should understand that nanofiltration does not retain monovalent ions such as sodium, potassium, and chlorine, but has a higher retention rate for divalent anions, and single membrane electrodialysis solves the problem of divalent anion enrichment very well without causing the loss of metal catalysts.

[0023] Furthermore, in the alkali adjustment tank, the pH is adjusted to 6-9 by adding sodium hydroxide or potassium hydroxide.

[0024] Furthermore, the salt concentration of the influent of the biochemical unit should not exceed 5000 mg / L. When the influent salt concentration is too high, in order to ensure the treatment effect of the subsequent nitrification and denitrification bacteria, other low-salt wastewater dilution treatment should be used, preferably domestic sewage, steam stripping purified water and other wastewater, whose salt concentration, COD, etc. are relatively low.

[0025] Furthermore, the biochemical unit adopts a combined process of A / O and post-denitrification; the A / O process has the A section in front and the O section in the back, the A section is mainly used to improve the biodegradability of wastewater and accelerate the biodegradation rate, the O section is mainly used for the removal of organic matter and the nitrification reaction of residual ammonia nitrogen, the post-denitrification is used to remove total nitrogen, convert nitrate nitrogen and nitrite nitrogen into nitrogen gas for removal, and the A / O process also has a certain dephosphorization function.

[0026] Furthermore, magnesium chloride and ammonia are added to the reaction tank in a P:Mg:N molar ratio close to 1:1:1, and when the pH in the system is less than 7, sodium hydroxide or potassium hydroxide is added to make the pH of the system greater than 7.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) In view of the characteristics of high COD, high organic phosphorus, high toxicity and difficulty in degradation of organic phosphine wastewater, the present invention adopts a treatment process with homogeneous catalytic wet oxidation as the core, giving full play to the characteristics of high catalytic activity and strong treatment capacity of homogeneous catalytic wet oxidation, and ultimately achieving the discharge of organic phosphine wastewater in compliance with the standards.

[0029] (2) The present invention solves the problem of catalyst loss in homogeneous catalytic wet oxidation by combining wet oxidation with membrane technologies such as nanofiltration membrane and electrodialysis single anion membrane, realizes the recycling of catalyst, and greatly reduces the cost of catalyst, especially precious metal catalyst.

[0030] (3) The single anion membrane electrodialysis technology adopted in the present invention solves the problem of enrichment and separation of orthophosphate, and finally converts orthophosphate into fertilizer struvite by adding magnesium chloride and ammonia, thereby realizing the resource utilization of phosphorus.

[0031] (4) The present invention solves the problem of salt concentration while wet oxidation cycle treatment, preventing scaling and clogging of process pipelines. The nanofiltration membrane used in the present invention effectively removes most of the monovalent salts such as sodium chloride and potassium chloride in the wastewater while intercepting high-valent metal ions and high-valent anions, reducing the accumulation of salts; the single membrane electrodialysis used can remove most of the anion salts in the wastewater, such as phosphates, sulfates, carbonates, etc., achieving salt balance in the wet oxidation cycle treatment process.

[0032] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 . Flow chart of the treatment of organic phosphine wastewater according to the present invention. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with specific examples. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples.

[0035] Example 1

[0036] use Figure 1 The process method shown treats organic phosphine wastewater.

[0037] Process flow such as Figure 1 As shown: the organic phosphine wastewater first enters the regulating tank, is mixed with the single membrane electrodialysis mother liquor and the homogeneous catalyst, and then enters the heat exchange unit. The heat exchange unit uses a heat exchanger to exchange heat between the effluent of the wet oxidation reactor and the effluent of the regulating tank, and enters the wet oxidation reactor after heat exchange and temperature increase; the effluent of the wet oxidation reactor enters the heat exchange unit for heat exchange and cooling, and then enters the acid adjustment tank after being cooled by the cooler. The effluent of the acid adjustment tank enters the nanofiltration. After the nanofiltration concentrated water is treated by single membrane electrodialysis, the mother liquor is returned to the regulating tank, and the anion liquid flows to the phosphorus recovery section reaction tank. By adding magnesium chloride and ammonia, magnesium ammonium phosphate precipitate is finally produced. The precipitate is filtered, concentrated and crystallized to generate the product struvite. The supernatant and nanofiltration produced water are sent to the biochemical treatment section alkali adjustment tank together; the effluent of the alkali adjustment tank enters the biochemical unit. The biochemical unit adopts an A / O and post-denitrification combined process. After the treatment, it is discharged to the effluent monitoring tank and finally meets the discharge standards.

[0038] The water quality of a certain stream of organic phosphine wastewater containing ATMP (aminotrimethylenephosphonic acid) is as follows: COD 21000mg / L, total salt content 14000mg / L, sulfate concentration 600mg / L, organic phosphorus 3100mg / L, inorganic phosphorus 200mg / L, total nitrogen 1100mg / L, and wastewater flow rate 10t / h.

[0039] The specific operating conditions for treating ATMP-containing organic phosphine wastewater are as follows: the above-mentioned organic phosphine wastewater first enters a regulating tank, where it is mixed with the single membrane electrodialysis mother liquor and a homogeneous catalyst. After mixing, the flow rate becomes 11.6 t / h; the homogeneous catalyst adopts a palladium-iron composite catalyst, which is a mixed salt of palladium chloride and ferric chloride. After mixing, the palladium metal ion concentration in the liquid is about 10 mg / L, and the iron metal ion concentration is about 150 mg / L. After heat exchange, the wastewater temperature of the regulating tank outlet water rises to 150°C and enters a wet oxidation reactor; the reaction temperature of the wet oxidation reactor is 185°C, the pressure is 3 MPa, and the liquid space velocity is 2 h -1 , the gas-liquid volume ratio is 100:1; the wet oxidation effluent is cooled to 65°C by the heat exchange unit, and then cooled to 45°C by the cooler, and enters the acid adjustment tank. By adding hydrochloric acid, the pH is reduced to 3.5, and the effluent enters the nanofiltration; the nanofiltration membrane pore size is 1.5nm, the water production rate is 74.1%, and the metal catalysts, phosphates, sulfates, macromolecular organic matter (including ATMP), etc. are intercepted and enter the concentrated water side, and most of the sodium, potassium, chloride ions, ammonia nitrogen, small molecular organic matter, etc. pass through the nanofiltration membrane into the water production side; the nanofiltration concentrated water enters the single-mode electrodialysis treatment, the single-mode electrodialysis anion liquid flows to the reaction tank, and the mother liquor flows to the adjustment tank; the main component of the anion liquid is orthophosphate, and magnesium chloride is added to the reaction tank according to the P:Mg:N molar ratio of 1:1:1 and ammonia to generate ammonium magnesium phosphate precipitation. In order to make the precipitation more complete, a small amount of sodium hydroxide is added to adjust the pH to 7.5. The filtered precipitation is sent to the concentration crystallization unit, and finally the struvite with a purity of more than 96% is generated; the supernatant of the reaction tank enters the alkali adjustment tank together with the nanofiltration water, and the pH is raised to 6.5 by adding sodium hydroxide, and then enters the biochemical unit; the influent salt of the biochemical unit is relatively high. Considering the requirements of subsequent nitrification and denitrification microorganisms for salt, the stripping purified water is used as make-up water to dilute the salt; the biochemical unit adopts A / O process plus post-denitrification, and the final effluent COD is 45mg / L, the total salt content is 4002mg / L, the total phosphorus is less than 1mg / L, and the total nitrogen is 12mg / L, which meets the external discharge standard and can be discharged from the effluent monitoring pool. The pollution factor removal effect of each unit is shown in Table 1, and the treatment efficiency of each unit is shown in Table 2.

[0040] Table 1

[0041]

[0042] Table 2

[0043]

[0044] It can be seen from this embodiment that the process method of the present invention realizes efficient operation of homogeneous catalytic wet oxidation. In view of the problems of high COD, high organic phosphorus, high toxicity, and difficulty in degradation of organic phosphine wastewater, the COD removal rate of the wet oxidation unit of this embodiment is as high as 92.9%, the total nitrogen removal rate is as high as 89%, and the organic phosphorus removal rate is as high as 98.3%, and finally the organic phosphine wastewater is discharged up to the standard. At the same time, through the combination with membrane technology, the loss problem of homogeneous catalyst is solved, and the recycling of catalyst and resource utilization of phosphorus are realized.

[0045] Example 2

[0046] use Figure 1 The process method shown treats organic phosphine wastewater.

[0047] The water quality of a certain organic phosphine pesticide wastewater is as follows: COD 38000mg / L, total salt content is 18000mg / L, sulfate concentration is 800mg / L, organic phosphorus is 4200mg / L, inorganic phosphorus is 300mg / L, total nitrogen is 2500mg / L, and wastewater flow rate is 10t / h.

[0048] The specific operating conditions for treating the organic phosphine pesticide wastewater are as follows: the organic phosphine pesticide wastewater first enters a regulating tank, where it is mixed with a single membrane electrodialysis mother liquor and a homogeneous catalyst, and the flow rate becomes 11.5 t / h after mixing; the homogeneous catalyst adopts a palladium-copper composite catalyst, which is a mixed salt of palladium chloride and copper chloride. After mixing, the palladium metal ion concentration in the liquid is about 12 mg / L, and the copper metal ion concentration is about 170 mg / L. After heat exchange, the wastewater temperature of the regulating tank outlet water rises to 155°C and enters a wet oxidation reactor; the reaction temperature of the wet oxidation reactor is 180°C, the pressure is 3.5 MPa, and the liquid space velocity is 2 h -1, the gas-liquid volume ratio is 100:1; the wet oxidation effluent is cooled to 65°C by the heat exchange unit, and then cooled to 45°C by the cooler, and enters the acid adjustment tank. By adding hydrochloric acid, the pH is reduced to 4.5, and the effluent enters the nanofiltration; the nanofiltration membrane pore size is 1nm, the water production rate is 69.6%, metal catalysts, phosphates, sulfate macromolecules (including ATMP), etc. are intercepted and enter the concentrated water side, and most of the sodium, potassium, chloride ions, ammonia nitrogen, small molecular organic matter, etc. pass through the nanofiltration membrane into the water production side; the nanofiltration concentrated water enters the single-mode electrodialysis treatment, the single-mode electrodialysis anion liquid flows to the reaction tank, and the mother liquor flows to the adjustment tank; the anion liquid is mainly composed of orthophosphate, and it is in the reaction tank according to Magnesium chloride and ammonia were added in a P:Mg:N molar ratio of 1:1:1 to generate magnesium ammonium phosphate precipitation. In order to make the precipitation more complete, a small amount of sodium hydroxide was added to adjust the pH to 7.8. The filtered precipitation was sent to the concentration crystallization unit to finally generate struvite with a purity of more than 97%; the supernatant of the reaction tank and the nanofiltration water were sent to the alkali adjustment tank together, and the pH was raised to 6.6 by adding sodium hydroxide, and then entered the biochemical unit; the influent salt of the biochemical unit was high, and considering the requirements of subsequent nitrification and denitrification microorganisms for salt, domestic sewage was used as make-up water to dilute the salt; the biochemical unit adopted the A / O process plus post-denitrification, and the final effluent COD was 45mg / L, the total salt content was 4033 mg / L, the total phosphorus was less than 1mg / L, and the total nitrogen was 14mg / L, which met the external discharge standard and could be discharged from the effluent monitoring pool. The removal effect of pollution factors of each unit is shown in Table 3, and the treatment efficiency of each unit is shown in Table 4.

[0049] Table 3

[0050]

[0051] Table 4

[0052]

[0053] It can be seen from this embodiment that the process method of the present invention can treat organic phosphine wastewater of different concentrations and types, and ultimately achieves the discharge of organic phosphine wastewater in accordance with various indicators by adjusting the catalyst type, catalyst addition amount, nanofiltration water production rate and other methods.

[0054] Example 3

[0055] The water quality of the treated organic phosphine wastewater is the same as that in Example 1, and the process route, implementation steps, and reaction parameters are also the same as those in Example 1, except that the type of catalyst is different, as shown in Table 5.

[0056] Table 5

[0057]

[0058] It can be seen from this example that when the palladium-copper composite catalyst is used with the same dosage, the COD removal rate and organic phosphorus removal rate of the homogeneous catalytic wet oxidation are slightly lower than those in Example 1, and the total nitrogen removal rate is slightly higher.

[0059] Example 4

[0060] The water quality of the treated organic phosphine wastewater is the same as that in Example 1, and the process route, implementation steps, and reaction parameters are also the same as those in Example 1, except that the type of catalyst is different, as shown in Table 6.

[0061] Table 6

[0062]

[0063] It can be seen from this example that when the palladium-nickel composite catalyst is used with the same dosage, the COD removal rate, total nitrogen removal rate and organic phosphorus removal rate of the homogeneous catalytic wet oxidation are all reduced compared with Example 1.

[0064] Example 5

[0065] The water quality of the treated organic phosphine wastewater is the same as that in Example 1, and the process route, implementation steps, and reaction parameters are also the same as those in Example 1, except that the type of catalyst is different, as shown in Table 7.

[0066] Table 7

[0067]

[0068] It can be seen from this embodiment that by using a rhodium-copper composite catalyst with the same dosage, the COD removal rate, total nitrogen removal rate and organic phosphorus removal rate of the homogeneous catalytic wet oxidation are further improved compared with Example 1.

[0069] Example 6

[0070] The water quality of the treated organic phosphine wastewater is the same as that in Example 1, and the process route, implementation steps, and reaction parameters are also the same as those in Example 1, except for the type of catalyst, as shown in Table 8.

[0071] Table 8

[0072]

[0073] It can be seen from this example that when a platinum-copper composite catalyst is used with the same dosage, the COD removal rate and organic phosphorus removal rate of the homogeneous catalytic wet oxidation are basically close to those of Example 1, but the total nitrogen removal rate is reduced to 86.5%.

[0074] Example 7

[0075] The water quality of the treated organic phosphine wastewater is the same as that in Example 1, and the process route, implementation steps, and reaction parameters are also the same as those in Example 1, except for the type of catalyst, as shown in Table 9.

[0076] Table 9

[0077]

[0078] It can be seen from this example that when the platinum-nickel composite catalyst is used, the COD removal rate, total nitrogen removal rate and organic phosphorus removal rate of the homogeneous catalytic wet oxidation are significantly reduced compared with those of Example 1.

[0079] Example 8

[0080] The water quality of the treated organic phosphine wastewater is the same as that in Example 1, and the process route, implementation steps, and reaction parameters are also the same as those in Example 1. Only the type and dosage of the catalyst are different, as shown in Table 10.

[0081] Table 10

[0082]

[0083] It can be seen from this embodiment that when a platinum-nickel composite catalyst is used, the dosage is increased compared with Example 7, and the corresponding homogeneous catalytic wet oxidation COD removal rate and organic phosphorus removal rate are significantly increased compared with Example 7, and are basically close to Example 1, and the total nitrogen removal rate does not change significantly.

[0084] Comparative Example 1

[0085] The water quality of the treated organic phosphine wastewater is the same as that in Example 1, and the process route, implementation steps, and reaction parameters are also the same as those in Example 1, but no precious metal catalyst is added, and only a transition metal catalyst is added, as shown in Table 11 for details.

[0086] Table 11

[0087]

[0088] It can be seen from this comparative example that without adding precious metal catalysts, but only adding copper metal catalysts, the COD removal rate and total nitrogen removal rate of homogeneous catalytic wet oxidation decreased significantly, the COD removal rate was only 65.1%, the total nitrogen removal rate was only 62.5%, and the organic phosphorus removal rate was only 67.2%.

[0089] Comparative Example 2

[0090] The water quality of the treated organic phosphine wastewater is the same as that in Example 1, and the process route, implementation steps, and reaction parameters are also the same as those in Example 1, but no precious metal catalyst is added, and only a transition metal catalyst is added, as shown in Table 12 for details.

[0091] Table 12

[0092]

[0093] It can be seen from this comparative example that no precious metal catalyst is added, only copper metal catalyst is added. Compared with comparative example 1, the copper metal dosage is increased to 500 mg / L. It can be seen that the COD removal rate and total nitrogen removal rate of homogeneous catalytic wet oxidation are significantly improved, but there is still a certain gap with Example 2.

[0094] Comparative Example 3

[0095] The water quality of the treated organic phosphine wastewater is the same as that in Example 1, and the process route, implementation steps, and reaction parameters are also the same as those in Example 1. The reaction temperature of the wet oxidation reactor is 185°C, the pressure is 3 MPa, and the liquid space velocity is 2 h -1 , the gas-liquid volume ratio is 100:1, and neither precious metal catalyst nor transition metal catalyst is added. See Table 13 for details.

[0096] Table 13

[0097]

[0098] It can be seen from this comparative example that without adding a catalyst and using conventional wet oxidation, the reaction conditions are the same as those in Example 1, and the final COD removal rate is only 30.2%, and the total nitrogen removal rate is only 10.3%.

[0099] Comparative Example 4

[0100] The water quality of the treated organic phosphine wastewater is the same as that in Example 1, and the process route, implementation steps, and reaction parameters are also the same as those in Example 1. The reaction temperature of the wet oxidation reactor is 280°C, the pressure is 6 MPa, and the liquid space velocity is 2 h -1 , the gas-liquid volume ratio is 100:1, and neither precious metal catalyst nor transition metal catalyst is added. See Table 14 for details.

[0101] Table 14

[0102]

[0103] It can be seen from this comparative example that without adding a catalyst and using conventional wet oxidation, the temperature and pressure of the wet oxidation reactor are greatly increased, and other conditions remain unchanged. The final COD removal rate and organic phosphorus removal rate are improved, but there is still a large gap compared with Example 1, and the total nitrogen removal rate has always been at a low level.

Claims

1. A method for treating organic phosphine wastewater by homogeneous catalytic wet oxidation, comprising a wet oxidation section, a biochemical treatment section and a phosphorus recovery section; The wet oxidation section includes a regulating tank, a heat exchange unit, a wet oxidation reactor, a cooler, an acid adjustment tank, nanofiltration and single membrane electrodialysis; the organic phosphine wastewater, the homogeneous catalyst and the mother liquor of the single membrane electrodialysis are mixed in the regulating tank and then enter the heat exchange unit, and heat exchange and temperature increase with the effluent of the wet oxidation reactor, and then enter the wet oxidation reactor; the effluent of the wet oxidation reactor is heat exchanged by the heat exchange unit and then cooled by the cooler, and then enters the acid adjustment tank, the effluent of the acid adjustment tank enters the nanofiltration, the concentrated water of the nanofiltration enters the single membrane electrodialysis treatment, the single membrane electrodialysis mother liquor is returned to the regulating tank, the anion liquid enters the phosphorus recovery section, and the nanofiltration produced water enters the biochemical treatment section; in, The homogeneous catalyst is a composite catalyst of precious metal and transition metal; the precious metal is selected from one or more of platinum, palladium, rhodium, silver and ruthenium, and the transition metal is selected from one or more of copper, iron, manganese, zinc and nickel, wherein the mass percentage of the precious metal in the homogeneous catalyst is 1% to 20%; the precious metal and the transition metal exist in the form of metal salt compounds or complexes and are dissolved in the liquid phase; The nanofiltration water production rate is 60% to 85%, the membrane pore size is between 1 and 3 nm, and the metals, high-valent salts, unreacted organic phosphorus and other macromolecular organic matter of the homogeneous catalyst are intercepted and enter the concentrated water side after interception; The single membrane electrodialysis uses only anionic membranes. Under the action of the electrode drive and anionic membranes, high-valent anionic salts and negative small molecular organic matter in the nanofiltration concentrate pass through the anionic membrane into the concentrate side, and the cationic catalyst remains in the mother liquor and is reused again. The biochemical treatment section includes an alkali adjustment tank, a biochemical unit and an effluent monitoring tank in sequence; the biochemical unit adopts an A / O and post-denitrification combined process, and is discharged to the effluent monitoring tank after the treatment is completed, and finally meets the discharge standards; The phosphorus recovery section includes a reaction tank and a concentration crystallization unit. The reaction tank produces magnesium ammonium phosphate precipitate by adding magnesium chloride and ammonia to phosphate. The precipitate is sent to the concentration crystallization unit to finally form the product struvite; the supernatant is sent to the alkali adjustment tank.

2. The method according to claim 1, characterized in that The heat exchange unit is composed of a plurality of heat exchangers, and performs heat exchange on the outlet water of the wet oxidation reactor and the outlet water of the regulating tank. The outlet water of the wet oxidation reactor goes through the tube side, and the outlet water of the regulating tank goes through the shell side.

3. The method according to claim 2, characterized in that After heat exchange, the wastewater temperature rises to 130-160°C, and the outlet water temperature of the wet oxidation reactor drops to 50-75°C.

4. The method according to claim 1, characterized in that The homogeneous catalyst is a palladium-copper or palladium-iron composite catalyst.

5. The method according to claim 4, characterized in that The homogeneous catalyst is added according to the COD mass concentration and metal ion mass concentration ratio of 2000:1 to 2:1, and is appropriately supplemented according to the catalyst loss rate and the change of reaction liquid concentration during normal operation.

6. The method according to claim 1, characterized in that The wet oxidation reactor is a bubbling flow internal circulation reactor with an inner cylinder, which uses oxygen as an oxidant to oxidize general organic matter in water into small molecular organic matter or inorganic matter.

7. The method according to claim 6, characterized in that The reaction temperature of the wet oxidation reactor is 150-300°C, the reaction pressure is 2MPa-10MPa, and the liquid space velocity is 0.25-4h -1 , the gas-liquid volume ratio is 20:1~500:

1.

8. The method according to claim 1, characterized in that: The cooler cools the outlet water of the wet oxidation reactor to 25-40°C.

9. The method according to claim 1, characterized in that: In the acid adjustment tank, the pH is adjusted to 3-6 by adding hydrochloric acid or sulfuric acid.

10. The method according to claim 1, characterized in that In the alkali adjustment tank, the pH is adjusted to 6-9 by adding sodium hydroxide or potassium hydroxide.

11. The method according to claim 1, characterized in that: The salt concentration of the influent of the biochemical unit does not exceed 5000 mg / L, and the biochemical unit adopts an A / O and post-denitrification combined process; the A / O process has the A section in front and the O section in the back.

12. The method according to claim 1, characterized in that The magnesium chloride and ammonia added to the reaction tank are added in a P:Mg:N molar ratio of 1:1:

1. When the pH in the system is less than 7, sodium hydroxide or potassium hydroxide is added to make the pH of the system greater than 7.

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