SAME

FIELD OF THE INVENTION

[0001] The present invention relates to the technical fields of environmental protection and wastewater treatment, particularly to a catalytic wet oxidation reaction tower (or reaction column), as well as a method and apparatus for treating high concentration organic wastewater using the same.

BACKGROUND OF THE INVENTION

[0002] China is facing a water resources crisis now. With the rapid development of economy, the total discharge of waste water is increasing rapidly, and the 2/3 of the rivers are polluted and has lost the function of drinking water source. It can be easily seen from the analysis of the current situation of wastewater treatment that, the most of the industrial wastewater, which was untreated and directly discharged or had undergone a certain degree of treatment but failed to meet the discharging standard, is the high concentration organic wastewater difficult to treat. Some of the high concentration, refractory industrial organic wastewater is difficult to be effectively treated, such as pesticide wastewater, dye wastewater, leather wastewater and polyurethane wastewater. Because of its non-biodegradability and toxicity for microorganisms, the above-mentioned wastewater is difficult to be effectively degraded by the traditional microbial methods, and thus the demand for the treatment technology of high concentration of the refractory wastewater is becoming urgent increasingly. The National Major Science and Technology Program for Water Pollution Control and Treatment regarded "high concentration of the refractory organic wastewater deep oxidation equipment development and industrialization" as a focus of research of the Water Special Project of "the Twelfth Five-year Plan of China". On the other hand, due to continuous innovation of the production process, the industrial wastewater discharging is reduced, but its concentration becomes higher, and the treatment of high concentration wastewater is of universal significance.

[0003] At present, the effective methods for treatment of high concentration organic wastewater primarily include the biochemical sludge method, incineration, supercritical oxidation, the catalytic wet oxidation method and so on. The biochemical sludge process is a combination process using microorganisms and activated sludge, has the advantages of stable effluent and low operation cost, but exerts a strict requirement on the conditions of the wastewater (i.e., only suitable for the wastewater having high biodegradability), and the process covers a large land area, and the sludge produced needs to be treated once more. Incineration treatment can remove organic pollutants in wastewater effectively, but needs to add a combustion improver in the wastewater incineration process, resulting in high treatment cost (300-400 RMB Yuan/ton for the heavy oil burning method used usually in the industry). The supercritical oxidation method may remove the organic matter in wastewater completely, but it has the disadvantages of harsh reaction conditions (30-40MP a, 400-600 ^° C ), large equipment investment, and high energy consumption. Catalytic wet air oxidation (referred to simply as CWAO) is one of the best ways to the treatment of high concentration, toxic, harmful, biorefractory organic wastewater at present, and the method is an advanced environmental technology for treating high concentration organic wastewater, developed based on wet oxidation method (referred to simply as WAO) in the mid-eighties of twentieth century, which is a wastewater purification technology wherein the organic wastewater is oxidized by air under the action of a catalyst at high temperature and high pressure, such that the organic matters and ammonia nitrogen in the high concentration of refractory sewage are oxidized and decomposed respectively into harmless substances such as C0 ₂ , H ₂ 0, and N ₂ . Through the technology of wastewater treatment, BOD can be greatly increased, so as to improve sewage biodegradability. The reaction mechanism is shown in Figure 1.

[0004] CWAO technology can be applied to the polyurethane industry, such as flammable and explosive substances and high concentration of biorefractory industrial wastewater produced in the synthesis of diphenyl methane diisocyanate (abbreviated MDI), isophorone diisocyanate (abbreviated IPDI), polyester/polyether polyol products and the like, as well as its upstream and downstream industry chain related production. Furthermore, it can also be extensively used for treating the high concentration, toxic industrial wastewater, which is difficult to be treated by other methods, produced in coking, pharmaceutical, petrochemical, textile printing and dyeing, organic pesticide and other industries. The technology has the advantages of wide application range, high purification efficiency, small occupation area, low energy consumption, less secondary pollution etc., and thus has a broad application prospect. However, the three phases of gas phase, liquid phase and solid phase are mixed at high temperature and pressure, and salting-out of the wastewater may lead to the problems of pipeline blockage, equipment corrosion etc., which seriously restrict the industrial development and application of the technology.

[0005] At present, CWAO technology in China is still in the development stage of industrialization, many published patents and publications describe the preparation and study of the catalysts used for the technology, such as CN1358567, CN101185887, CN201110427159.8, CN102040274 etc., and major research institutions comprise Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Tongji University, Tsinghua University etc. Particularly, Dalian Institute of Chemical Physics, Chinese Academy of Sciences is leading in the study of the catalysts for catalytic wet oxidation in China, and filed a patent application about a noble metal-rare earth bimetallic catalyst which makes a difference from the foreign single precious metal catalyst and has been granted a patent right (grant number: CN1045076C), and its cost performance is superior to similar foreign catalyst. But for the development of the apparatus for CWAO, only a few sets of experimental equipment have been reported.

[0006] CN101372371 describes a process of treating small molecular organic acids and ammonia nitrogen in garbage leachate using CWAO, wherein a 1L autoclave is used for experimental study, and the mixing reaction of the gas liquid solid three-phase is achieved by rapid mixing in the autoclave. The process is difficult to be amplified to the industrialization process of CWAO, further, carbon deposition easily occurs during the reaction, which will lead to the deactivation of the catalyst.

[0007] CN 2668621Y describes a trickle-bed type of small CWAO reaction apparatus for laboratory research, provided additionally with a back flush device for periodically flushing the catalyst in the reactor, which solves the problem of catalyst deactivation incurred by salt deposition during use. However, a simple mixing tank is used for mixing of gas phase and liquid phase, and thus the mixing effect is limited. Further, the process is complicated, and can not be operated stably after the realization of industrialization.

[0008] CN203079735U describes an apparatus for catalytic wet air oxidation of high COD wastewater. A homogeneous catalyst is used to conduct the catalytic reaction in the process using the apparatus, and Cu, Fe, Mn and other metal ions are contained in treated wastewater, resulting in secondary pollution and the need for secondary processing. Further, a tube-type gas-liquid mixer is used in the apparatus, gas-liquid mixing efficiency is low, and oxygen can not be fully mixed and reacted, resulting in reduction of the removal rate of COD and increasing of the operation cost. [0009] In the CWAO process described or cited in the above literatures, mixing is conducted mainly by the use of a simple pipeline or mechanical agitation, which is difficult to realize the full mixing of gas-liquid two-phase, resulting in a limited wastewater COD removal rate. Taking into account waste water complexity, particularly in the implementation of a large scale continuous production process, the problem of the pipeline and reactor plugging is prone to occur due to salting-out of the wastewater under high temperature and pressure conditions, such that the industrial application and popularization of the technology is greatly restricted. Therefore, according to the technical characteristics of the treatment of high concentration organic wastewater by CWAO, it needs to develop a reaction processes and device having a higher mixing efficiency and good anti-clogging ability.

Summary of the Invention

[0010] In view of the above-said problems in the prior art, the object of the present invention is to provide a catalytic wet oxidation reaction tower (also called as reaction column), as well as a method and apparatus for treating high concentration organic wastewater using the same. Mainly by enhancing the mixing of gas and liquid under conditions of high temperature and pressure, the present invention may reduce the phenomenon of decreased efficiency of wastewater treatment caused by the uneven gas-liquid mixing. Particularly by the use of unique high pressure gas and liquid distributors in the reaction tower, the present invention can avoid the occurrence of salt deposition and plugging on pipeline and the inner wall of the devices due to salting-out of high concentration wastewater under high temperature and pressure conditions, and can significantly simplify the process flow, such that the CWAO industrialized device can stably and cost-effectively treat high concentration organic wastewater.

[0011] The technical solution of the present invention used to achieve the above-said object is described as below.

[0012] 1. A reaction tower for treating high concentration organic wastewater by catalytic wet air oxidation, characterized in that: said reaction tower (reactor) is provided with a high pressure gas distributor(s) and a high pressure liquid distributor(s) used to achieve substantial mixing of gas-liquid two phase in the interior space of the reaction tower, preferably in the bottom of the interior space of reaction tower, wherein the high pressure gas distributor(s) is located at the bottom of the reaction tower, and the high pressure liquid distributor(s) is located above the high pressure gas distributor(s). Preferably, the high pressure liquid distributor(s) may be located 5cm ~ 100cm above the high pressure gas distributor(s), preferably 5cm ~ 60cm, more preferably 15cm ~ 40cm above the high-pressure gas distributor(s), but not limited to the above recited values, e.g., the high pressure liquid distributor(s) may be located 150cm above the high-pressure gas distributor(s), as long as gas-liquid two-phase can be fully mixed in the reaction tower or the reactor.

[0013] 2. The reaction tower according to the above Item 1, wherein said high pressure liquid distributor(s) is one or more (preferably 2-20, more preferably 3-15, more preferably 4-10, for example 5,6,7,8) hollow tubes extending into the reaction tower, the space in the tube (or cavity) is wastewater flow passage, and a plurality (preferably 5-100, more preferably 10-80, more preferably 15-70, more preferably 20-50) of wastewater jet orifices are provided in the lower side of each of the hollow tube.

[0014]3. The reaction tower according to the above Item 2, wherein the three-dimensional shape of the wastewater jet orifices of the high pressure liquid distributor is cone, pyramid, circular truncated cone, cylindrical, square or rectangular, preferably circular truncated cone. The wastewater flow passage of the high pressure liquid distributor(s) is for example a hollow tube having trapezoidal, triangular, rectangular or annular shaped cross section.

[0015] 4. The reaction tower according to the above Item 2 or 3, wherein the cross section of the wastewater flow passage is trapezoidal shape. There is no particular limitation on the number and size of the wastewater jet orifices, which are preferably such that the wastewater is substantially uniformly distributed in the reaction tower downward or upward. The reaction tower has an inner diameter of generally 200-2500 mm, preferably 450-1400 mm, and a height of 2-25 m, preferably 4-12 m. The length of the hollow tube extending into the interior of the reaction tower is preferably 50% to 99% of the inner diameter of the reaction tower, preferably 70 to 95%), more preferably 80 to 90%. The inner diameter of the wastewater flow passage at the end proximal to the position of the tower side-wall through which the hollow tube extends into the reaction tower is generally 10-50 mm, preferably 25-40mm, the inner diameter of the distal end of the water flow passage is generally 5-40mm, preferably 15-30mm. The diameter (or equivalent diameter) of the wastewater jet orifices is 1-lOmm, more preferably 2-6mm.

[0016] 5. The reaction tower according to any of the above items 1-4, wherein the high pressure gas distributor(s) can be any gas high pressure distributor which may achieve substantially uniform distribution of the gas. It preferably comprises one or more (preferably 2-20, more preferably 3-15, more preferably 4-10, e.g. 5, 6) gas passage member(s) (the gas passage member(s) has a plurality of gas distribution holes distributed around its peripheral wall, for example it is a hollow tube-shaped gas passage having a plurality of gas distribution holes on the tube wall), and inert filler filled around the gas passage member(s), and a metal mesh enclosing the inert filler and the gas passage member(s). High pressure gas is introduced into the high pressure gas distributor(s), passed through the gas distribution holes provided on the gas passage member(s) and the inert filler, finally entered into the reaction tower through the outside metal mesh of the high pressure gas distributor(s), and then mixed and reacted in the catalyst bed with the wastewater introduced through the high pressure liquid distributor(s). Gas is introduced into the reaction tower via the high pressure gas distributor(s) under the pressure of 3-10MPa, preferably 5-8MPa. Gas flow is generally 300L/min~3000L/min, preferably 1200L/min ~2500L/min. The high pressure gas distributor(s) is arranged such that the high pressure gas is contacted with the liquid distributed by the high pressure liquid distributor(s) in the opposite direction. The flow ratio of the high pressure gas (e.g., air) and the high pressure liquid (e.g., the organic waste water) generally depends on the concentration of organic matter contained in waste water and the concentration of oxygen in the air, and those skilled in the art can readily be selected by calculating. Preferably, the flow ratio of the high-pressure gas (i.e., air) to the high pressure liquid (e.g., organic wastewater) should be such that: in accordance with the stoichiometry of the chemical reaction, oxygen is used in a mole excess of for example 50-600mol%, more preferably 100-500%, and more preferably 150-300mol%, relative to the amount of the organic matter in the high pressure liquid (e.g., the organic waste water).

[0017] 6. The reaction tower according to the above Item 5, wherein the shape of the gas passage member(s) in the high pressure gas distributor(s) is cone, pyramid, circular truncated cone, cylindrical, square or rectangular, preferably cylindrical. Preferably, the number of the gas passage member(s) is 1-20, more preferably 2-16, still more preferably 3-10, further more preferably 4-8. Gas is introduced from the top or the bottom of the gas passage, preferably from the top of the gas passage. Preferably the longitudinal axis of the gas passage is accordant with the longitudinal axis of the reaction tower. The gas passage height is 40 to 90% of the height of the high pressure gas distributor, preferably 50 to 80%>. The diameter of the gas passage is preferably 10- 160mm, more preferably 30-80mm. [0018] 7. The reaction tower according to the above Item 5 or 6, wherein the gas distribution holes on the gas passage is circular, diamond, square or rectangular shape, preferably rectangular; the number of the gas distribution holes of each gas passage is 1-20, preferably 5-10; and the gas distribution holes of the gas passage is symmetrically or asymmetrically distributed, preferably asymmetrically distributed. The equivalent diameter of the gas distribution holes is preferably l-8mm, more preferably 2.5-5mm.

[0019] 8. The reaction tower according to any of the above items 5-7, wherein the inert filler is structured packing or random packing, preferably random packing; preferred random packing is ceramic ring, Ti0 ₂ , Si0 ₂ , or activated carbon, etc., more preferably ceramic ring or Ti0 ₂ .

[0020] 9. The reaction tower according to any of the above items 5-7, wherein the metal mesh is made of Fe, Cu, Ti, Ni and other materials, preferably made of Ti metal mesh. Preferred diameters of the sieve mesh is 10-100 μπι, preferably about 20-80 μπι, more preferably about

[0021] 10. A catalytic wet oxidation apparatus for treating high concentration organic wastewater, which comprises the reaction tower according to any one of the above items 1-9, a raw water storage tank for storing the high concentration organic wastewater, a high pressure pump, a filter, a high pressure buffer tank, a heat exchanger, an air compressor, a gas-liquid separation tank, an exhaust gas absorption tower and a wastewater buffer tank,

wherein the raw water storage tank is connected via the high pressure pump to the filter, the high pressure buffer tank and the heat exchanger through pipeline successively, the heat exchanger is further connected to the high pressure liquid distributor of the reaction tower,

the air compressor is further connected to the gas inlet pipe of the high pressure gas distributor, the outlet of the reaction tower is connected to the heat exchanger and the gas-liquid separation tank via pipeline successively,

the gas phase outlet of the gas liquid separation tank is connected to the exhaust gas absorption tower, and the liquid phase outlet of the gas liquid separation tank and the aqueous phase (or liquid phase) outlet of the exhaust gas absorption tower are connected to the wastewater buffer tank.

[0022] 11. A method of treating high concentration organic wastewater by catalytic wet oxidation, wherein:

in the catalytic wet oxidation device for treating high concentration organic wastewater according to above item 10, high concentration organic wastewater of COD^5000mg/L is passed sequentially through the raw water storage tank, the high pressure pump, the filter, the high pressure buffer tank, and the heat exchanger, distributed in the reaction tower by the high pressure liquid distributor, contacted and reacted in the reaction tower with the high pressure air compressed by the air compressor and distributed by the high pressure gas distributor, and then entered into gas-liquid separation tank for separation;

the gas phase separated is treated by the exhaust gas absorption tower for standard discharging, and the aqueous phase separated is discharged by the wastewater buffer tank. The high concentration organic wastewater refers to the organic wastewater having COD concentration of 5000mg / L, such as COD 5000 - 50000 mg/L, for example, 10000 - 35000mg/L.

[0023] 12. The method of treating high concentration organic wastewater by catalytic wet oxidation according to above item 11, wherein the wastewater treatment reaction conditions are as follows: reaction temperature 150-350 ^° C (preferably 180-280 ^° C), reaction pressure 3-9MPa (preferably 4-8MPa, such as 6MPa), COD concentration in wastewater^ 5000 mg/L, the wastewater feed amount 0.5-5 ton/hour (preferably 1.0-4 t/h, preferably 2-3 t/h), the volume flow ratio of high pressure gas and high pressure liquid introduced into the reaction tower 30-180: 1; preferably 50-120: 1.

[0024] In the CWAO process using the specially designed reaction tower and high pressure gas and liquid distributors described in the applications, the effect of COD treatment of the wastewater is greatly improved. In the treatment of a variety of high concentration organic wastewater systems, the removal rate of COD is >95%, meanwhile, the apparatus may stably be operated, the problems of plugging in the pipeline and the inner wall of the equipment and equipment corrosion caused by salting-out of the wastewater under high temperature and pressure conditions may be avoided, it may be applied for the treatment of various different systems of high concentration organic wastewater, and is not affected by the acidity-alkalinity of and the salt content of wastewater. Therefore, it can be demonstrated that, by using the method and apparatus for treating high concentration organic wastewater by means of catalytic wet oxidation, the gas-liquid-solid three-phase may be fully mixed and reacted, the efficiency of wastewater treatment is greatly improved, and the phenomena of equipment corrosion, pipeline blockage, etc. may be avoided. The method and apparatus significantly simplify the CWAO process flow, may sustainably and efficiently treat a variety of high concentration organic wastewater and successfully implement industrial development of CWAO processing technology, and thus have very important significance for large popularization and application of this technology in the field of environmental protection.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of the degradation mechanism of CWAO.

[0026] Figure 2 shows a process flow diagram of an embodiment for treatment of high concentration organic wastewater by catalytic wet air oxidation of the present invention.

[0027] Figure 3 is the enlarged view of the bottom of the reaction tower shown in Figure 2.

[0028] Figure 4 is an enlarged sectional view of the region A of the high-pressure liquid distributor of the reactor tower shown in Figure 3.

[0029] Figure 5 is an enlarged sectional view of the region B of the high-pressure liquid distributor of the reactor tower shown in Figure 3.

[0030] Figure 6 is the cross-sectional view taken along line C-C of the high-pressure liquid distributor of the reactor tower shown in Figure 3.

THE MODE OF CARRYING OUT THE INVENTION

[0031] The method and apparatus for treating high concentration organic wastewater by means of catalytic wet oxidation provided by the present invention are further described with reference to the Drawings and Examples, but the present invention should not be interpreted to be limited to them.

[0032] The method of treating high concentration organic wastewater by catalytic wet oxidation of the present invention is shown in Figure 2, primarily including a raw water storage tank 1, a high pressure pump 2, a filters 3, a high pressure buffer tank 4, a heat exchanger 5, an air compressor 6, a reaction tower 7, a gas-liquid separation tank 10, a exhaust gas absorption tower 11 and a wastewater buffer tank 12, wherein the bottom of the reaction tower is provided with a high pressure liquid distributor 8 and a high pressure gas distributor 9. High concentration organic wastewater (COD^5000mg/L) is passed sequentially through the raw water storage tank 1, the high pressure pump 2, the filter 3, the high pressure buffer tank 4, and the heat exchanger 5, distributed by the high pressure liquid distributor 8, mixed and reacted well with the high pressure air compressed by the air compressor 6 and distributed by the high pressure gas distributor 9 in the reaction tower 7, and then entered into gas-liquid separation tank 10 for separation. The gas phase separated is discharged up to standard after being treated by the exhaust gas absorption tower 11, and the aqueous phase separated is discharged up to standard after being collected by the wastewater buffer tank 12.

[0033] The structure of the high pressure liquid distributor 8 provided by the present invention is shown in Figures 3 and 4. The high pressure liquid distributor 8 is a trapezoidal (cross-section) hollow tube, the wastewater flow passage 13 is provided in its interior, and a plurality of wastewater jet orifices 14 are provided in its lower side. The high pressure wastewater is sprayed into the reaction tower 7 by the wastewater jet orifices 14 on the wastewater flow passage 13.

[0034] The structure of the high pressure gas distributor 9 provided by the present invention is shown in Figures 3, 5, and 6, which comprises a gas passage 15, gas distribution holes 16, inert filler 17, and a metal mesh 18. High pressure gas is introduced into the high pressure gas distributor 9, passed through the gas distribution holes 16 on the gas passage 15 and the inert filler 17, finally entered into the reaction tower through the outside metal mesh 18 of the high pressure gas distributor 9, and then mixed and reacted sufficiently in the catalyst bed with the wastewater introduced through the high pressure liquid distributor 8.

[0035] The method and apparatus for treating high concentration organic wastewater by means of catalytic wet oxidation of the present invention are described in details with reference to the Examples in combination with the Drawings, but the following Examples should not be construed as limiting the present invention, and the present invention only is defined by the claims.

[0036] The following Examples use CWAO industrial apparatus, which may treat 2 ton/hour of high concentration organic wastewater. The catalyst used in the apparatus is rare earth element Ce modified Ru/TiZr0 ₄ catalyst developed by Dalian Institute of Chemical Physics, Chinese Academy of Sciences. GB11914-89 potassium dichromate method is used as wastewater analysis methods for determination of COD Chemical Oxygen Demand value (COD) in wastewater, and DRB200 digestion reactor and HACH DR2800 spectrophotometer is used as COD analytical instrument. Biochemical Oxygen Demand after 5 Days (BOD5) is analyzed by BOD Trak™ Analyzer manufactured by Hach Company.

Example 1

[0037] The reaction apparatus is shown in Figure 2, and the reaction tower has the inner diameter of 900mm and the height of 10m. As shown Figures 2 and 3, the structure of the high pressure liquid distributor 8 is a trapezoidal (cross-section) hollow tube, the wastewater flow passage 13 is provided in its interior, and a plurality of circular truncated cone shaped wastewater jet orifices 14 are provided in the lower side of the hollow tube. The diameter of one end of the wastewater jet orifices at the inner wall of the distributor is 3mm, and the diameter of another end of the wastewater jet orifices at the outer wall of the distributor is 5mm. The length of the trapezoidal hollow tube extending into the interior of the reaction tower is 650mm, the diameter of the end of the wastewater flow passage located at (or proximal to) the inner wall of the reaction tower is 30mm, and the diameter of the distal end of the water flow passage is 15mm. The high pressure gas distributor 9 has the height of 400mm, and its structure is shown in Figures 3, 5 and 6. The rectangular gas distribution holes 16 are distributed asymmetrically on five gas passages 15. The gas passages have the diameter of 50mm and the height of 250mm, and the equivalent diameter of the gas distribution holes is 4mm. The ceramic ring inert filler 17 and Ti metal mesh 18 are used, and the mesh size of the metal mesh is 50μπι. The high pressure liquid distributor is arranged 30cm above the top of the high pressure gas distributor.

[0038] Isophorone diamine (abbreviated IPDA) high concentration organic wastewater (COD=24150 mg/L) is passed sequentially through the raw water storage tank 1, the high pressure pump 2, the filter 3, the high pressure buffer tank 4, and the heat exchanger 5 at 2 ton/hour (thereafter referred to as t/h) of feed rate, distributed by the high pressure liquid distributor 8, and mixed and reacted well in the reaction tower 7 with the high pressure air (2000L/min, pressure 6.7MPa) compressed by the air compressor 6 and distributed by the high pressure gas distributor 9. The reaction temperature is 265 ^° C, and the reaction pressure is 6.5MPa. The resulting reaction mixture is then entered into gas-liquid separation tank 10 for separation. The gas phase separated is discharged up to standard after being treated by the exhaust gas absorption tower 11, and the aqueous phase separated is supplied to the wastewater buffer tank 12. The analytical results are shown in Table 1.

Example 2

[0039] The reaction apparatus is shown in Figure 2, and the reaction tower has the inner diameter of 900mm and the height of 10m. As shown Figures 3 and 4, the structure of the high pressure liquid distributor 8 is a trapezoidal (cross-section) hollow tube, the wastewater flow passage 13 is provided in its interior, and a plurality of circular truncated cone shaped wastewater jet orifices 14 are provided in the lower side of the hollow tube. The diameter of one end of the wastewater jet orifices at the inner wall of the distributor is 4mm, and the diameter of another end of the wastewater jet orifices at the outer wall of the distributor is 6mm. The length of the trapezoidal hollow tube extending into the interior of the reaction tower is 650mm, the diameter of the end of the wastewater flow passage located at (or proximal to) the inner wall of the reaction tower is 30mm, and the diameter of the distal end of the water flow passage is 15mm. The high pressure gas distributor 9 has the height of 400mm, and its structure is shown in Figures 3, 5 and 6. The circular gas distribution holes 16 are distributed asymmetrically on two gas passages 15. The gas passages have the diameter of 100mm and the height of 250mm, and the equivalent diameter of the gas distribution holes is 6mm. The ceramic ring inert filler 17 and Ti metal mesh 18 are used, and the mesh size of the metal mesh is ΙΟΟμπι. The high pressure liquid distributor is arranged 15cm above the top of the high pressure gas distributor.

[0040] IPDA high concentration organic wastewater (COD=24150 mg/L) is passed sequentially through the raw water storage tank 1, the high pressure pump 2, the filter 3, the high pressure buffer tank 4, and the heat exchanger 5 at 2 t/h of feed rate, distributed by the high pressure liquid distributor 8, and mixed and reacted well in the reaction tower 7 with the high pressure air (1600L/min, pressure 6.7MPa) compressed by the air compressor 6 and distributed by the high pressure gas distributor 9. The reaction temperature is 265 ^° C, and the reaction pressure is 6.5MPa. The resulting reaction mixture is then entered into gas-liquid separation tank 10 for separation. The gas phase separated is discharged up to standard after being treated by the exhaust gas absorption tower 11, and the aqueous phase separated is supplied to the wastewater buffer tank 12. The analytical results are shown in Table 1.

Example 3

[0041] The reaction apparatus is shown in Figure 2, and the reaction tower has the inner diameter of 900mm and the height of 10m. As shown Figures 3 and 4, the structure of the high pressure liquid distributor 8 is a trapezoidal (cross-section) hollow tube, the wastewater flow passage 13 is provided in its interior, and a plurality of circular truncated cone shaped wastewater jet orifices 14 are provided in the lower side of the hollow tube. The diameter of one end of the wastewater jet orifices at the inner wall of the distributor is 4mm, and the diameter of another end of the wastewater jet orifices at the outer wall of the distributor is 6mm. The length of the trapezoidal hollow tube extending into the interior of the reaction tower is 650mm, the diameter of the end of the wastewater flow passage located at (or proximal to) the inner wall of the reaction tower is 40mm, and the diameter of the distal end of the water flow passage is 20mm. The high pressure gas distributor 9 has the height of 400mm, and its structure is shown in Figures 3, 5 and 6. The rectangular gas distribution holes 16 are distributed asymmetrically on five gas passages 15. The gas passages have the diameter of 50mm and the height of 250mm, and the equivalent diameter of the gas distribution holes is 4mm. The ceramic ring inert filler 17 and Ti metal mesh 18 are used, and the mesh size of the metal mesh is 50μπι. The high pressure liquid distributor is arranged 60cm above the top of the high pressure gas distributor.

[0042] 4,4-bis(sec-butylamino)-diphenylmethane (abbreviated MDBA) high concentration organic wastewater (COD=34650 mg/L) is passed sequentially through the raw water storage tank 1, the high pressure pump 2, the filter 3, the high pressure buffer tank 4, and the heat exchanger 5 at 2 t/h of feed rate, distributed by the high pressure liquid distributor 8, and mixed and reacted well in the reaction tower 7 with the high pressure air (2200L/min, pressure 7.2MPa) compressed by the air compressor 6 and distributed by the high pressure gas distributor 9. The reaction temperature is 270 ^° C, and the reaction pressure is 7.0MPa. The resulting reaction mixture is then entered into gas-liquid separation tank 10 for separation. The gas phase separated is discharged up to standard after being treated by the exhaust gas absorption tower 11, and the aqueous phase separated is supplied to the wastewater buffer tank 12. The analytical results are shown in Table 1.

Example 4

[0043] The reaction apparatus is shown in Figure 2, and the reaction tower has the inner diameter of 900mm and the height of 10m. As shown Figures 3 and 4, the structure of the high pressure liquid distributor 8 is a trapezoidal (cross-section) hollow tube, the wastewater flow passage 13 is provided in its interior, and a plurality of circular truncated cone shaped wastewater jet orifices 14 are provided in the lower side of the hollow tube. The diameter of one end of the wastewater jet orifices at the inner wall of the distributor is 4mm, and the diameter of another end of the wastewater jet orifices at the outer wall of the distributor is 6mm. The length of the trapezoidal hollow tube extending into the interior of the reaction tower is 650mm, the diameter of the end of the wastewater flow passage located at (or proximal to) the inner wall of the reaction tower is 40mm, and the diameter of the distal end of the water flow passage is 20mm. The high pressure gas distributor 9 has the height of 400mm, and its structure is shown in Figures 3, 5 and 6. The rectangular gas distribution holes 16 are distributed asymmetrically on five gas passages 15. The gas passages have the diameter of 50mm and the height of 250mm, and the equivalent diameter of the gas distribution holes is 4mm. The ceramic ring inert filler 17 and Ti metal mesh 18 are used, and the mesh size of the metal mesh is 50μπι. The high pressure liquid distributor is arranged 30cm above the top of the high pressure gas distributor.

[0044] Nitrobenzene high concentration organic wastewater (COD=28100 mg/L) is passed sequentially through the raw water storage tank 1, the high pressure pump 2, the filter 3, the high pressure buffer tank 4, and the heat exchanger 5 at 2 t/h of feed rate, distributed by the high pressure liquid distributor 8, and mixed and reacted well in the reaction tower 7 with the high pressure air (1800L/min, pressure 7.2MPa) compressed by the air compressor 6 and distributed by the high pressure gas distributor 9. The reaction temperature is 265 ^° C, and the reaction pressure is 7.0MPa. The resulting reaction mixture is then entered into gas-liquid separation tank 10 for separation. The gas phase separated is discharged up to standard after being treated by the exhaust gas absorption tower 11, and the aqueous phase separated is supplied to the wastewater buffer tank 12. The analytical results are shown in Table 1.

Example 5

[0045] The reaction apparatus is shown in Figure 2, and the reaction tower has the inner diameter of 900mm and the height of 10m. As shown Figures 3 and 4, the structure of the high pressure liquid distributor 8 is a trapezoidal (cross-section) hollow tube, the wastewater flow passage 13 is provided in its interior, and a plurality of circular truncated cone shaped wastewater jet orifices 14 are provided in the lower side of the hollow tube. The diameter of one end of the wastewater jet orifices at the inner wall of the distributor is 4mm, and the diameter of another end of the wastewater jet orifices at the outer wall of the distributor is 5mm. The length of the trapezoidal hollow tube extending into the interior of the reaction tower is 650mm, the diameter of the end of the wastewater flow passage located at (or proximal to) the inner wall of the reaction tower is 40mm, and the diameter of the distal end of the water flow passage is 20mm. The high pressure gas distributor 9 has the height of 400mm, and its structure is shown in Figures 3, 5 and 6. The rectangular gas distribution holes 16 are distributed asymmetrically on five gas passages 15. The gas passages have the diameter of 60mm and the height of 250mm, and the equivalent diameter of the gas distribution holes is 4mm. The ceramic ring inert filler 17 and Ti metal mesh 18 are used, and the mesh size of the metal mesh is 50μπι. The high pressure liquid distributor is arranged 40cm above the top of the high pressure gas distributor.

[0046] The thermoplastic polyurethane (abbreviated TPU) high concentration organic wastewater (COD=25800 mg/L) is passed sequentially through the raw water storage tank 1, the high pressure pump 2, the filter 3, the high pressure buffer tank 4, and the heat exchanger 5 at 2 t/h of feed rate, distributed by the high pressure liquid distributor 8, and mixed and reacted well in the reaction tower 7 with the high pressure air (1800L/min, pressure 7.2MPa) compressed by the air compressor 6 and distributed by the high pressure gas distributor 9. The reaction temperature is 265 ^° C, and the reaction pressure is 7.0MPa. The resulting reaction mixture is then entered into gas-liquid separation tank 10 for separation. The gas phase separated is discharged up to standard after being treated by the exhaust gas absorption tower 11, and the aqueous phase separated is supplied to the wastewater buffer tank 12. The analytical results are shown in Table 1.

Example 6

[0047] The reaction apparatus is shown in Figure 2, and the reaction tower has the inner diameter of 900mm and the height of 10m. As shown Figures 3 and 4, the structure of the high pressure liquid distributor 8 is a trapezoidal (cross-section) hollow tube, the wastewater flow passage 13 is provided in its interior, and a plurality of circular truncated cone shaped wastewater jet orifices 14 are provided in the lower side of the hollow tube. The diameter of one end of the wastewater jet orifices at the inner wall of the distributor is 3mm, and the diameter of another end of the wastewater jet orifices at the outer wall of the distributor is 5mm. The length of the trapezoidal hollow tube extending into the interior of the reaction tower is 650mm, the diameter of the end of the wastewater flow passage located at (or proximal to) the inner wall of the reaction tower is 30mm, and the diameter of the distal end of the water flow passage is 15mm. The high pressure gas distributor 9 has the height of 400mm, and its structure is shown in Figures 3, 5 and 6. The rectangular gas distribution holes 16 are distributed asymmetrically on five gas passages 15. The gas passages have the diameter of 50mm and the height of 250mm, and the equivalent diameter of the gas distribution holes is 4mm. The ceramic ring inert filler 17 and Ti metal mesh 18 are used, and the mesh size of the metal mesh is 50μπι. The high pressure liquid distributor is arranged 30cm above the top of the high pressure gas distributor.

[0048] The high concentration organic wastewater (COD=27210 mg/L) produced in the formaldehyde production is passed sequentially through the raw water storage tank 1, the high pressure pump 2, the filter 3, the high pressure buffer tank 4, and the heat exchanger 5 at 2 t/h of feed rate, distributed by the high pressure liquid distributor 8, and mixed and reacted well in the reaction tower 7 with the high pressure air (1700L/min, pressure 7.2MPa) compressed by the air compressor 6 and distributed by the high pressure gas distributor 9. The reaction temperature is 265 ^° C, and the reaction pressure is 7.0MPa. The resulting reaction mixture is then entered into gas-liquid separation tank 10 for separation. The gas phase separated is discharged up to standard after being treated by the exhaust gas absorption tower 11, and the aqueous phase separated is supplied to the wastewater buffer tank 12. The analytical results are shown in Table 1.

Comparative Example 1

[0049] In order to evaluate the method and apparatus for treating high concentration organic wastewater by CWAO provided by the present invention, a pipe type mixer is used for mixing reaction in this Comparative Example.

[0050] IPDA high concentration organic wastewater (COD=24150 mg/L) is passed sequentially through the raw water storage tank 1, the high pressure pump 2, the filter 3, the high pressure buffer tank 4, and the heat exchanger 5 at 2 t/h of feed rate, mixed with the high pressure air compressed by the air compressor 6 using the pipe type mixer, and then reacted in the reaction tower 7 (which does not comprise the high pressure liquid distributor 8 and the high pressure gas distributor 9). The reaction temperature is 265 ^° C, and the reaction pressure is 6.5MPa. The resulting reaction mixture is then entered into gas-liquid separation tank 10 for separation. The gas phase separated is discharged up to standard after being treated by the exhaust gas absorption tower 11, and the aqueous phase separated is supplied to the wastewater buffer tank 12. The analytical results are shown in Table 1.

Comparative Example 2

[0051] In order to evaluate the method and apparatus for treating high concentration organic wastewater by CWAO provided by the present invention, a pipe type mixer is used for mixing reaction in this Comparative Example.

[0052] MDBA high concentration organic wastewater (COD=34650 mg/L) is passed sequentially through the raw water storage tank 1, the high pressure pump 2, the filter 3, the high pressure buffer tank 4, and the heat exchanger 5 at 2 t/h of feed rate, mixed with the high pressure air compressed by the air compressor 6 using the pipe type mixer, and then reacted in the reaction tower 7 (which does not comprise the high pressure liquid distributor 8 and the high pressure gas distributor 9). The reaction temperature is 270 ^° C, and the reaction pressure is 7.0MPa. The resulting reaction mixture is then entered into gas-liquid separation tank 10 for separation. The gas phase separated is discharged up to standard after being treated by the exhaust gas absorption tower 11, and the aqueous phase separated is supplied to the wastewater buffer tank 12. The analytical results are shown in Table 1.