CN1830848A - Method and device for microwave heating and low-pressure treatment of high-concentration refractory organic wastewater - Google Patents

Abstract

A process for low-pressure treating of high-concentration organic sewage difficult to degrade by microwave heating and its apparatus are disclosed. Said process includes such steps as microwave irradiation, cyclic oxidizing including low-pressure aeration oxidizing, discharging or reusing the treated water, degradating, etc. Its apparatus is composed of microwave reactor with wave guide tube and glass window, cooler, water tank, high-pressure air cylinder.

Description

Method and device for microwave heating and low-pressure treatment of high-concentration refractory organic wastewater

technical field

The invention relates to a novel water treatment method and device combining microwave transmission technology, the structure of a microwave pressure vessel and wet catalytic oxidation technology, which is used for treating high-concentration, biologically refractory organic wastewater, and belongs to the field of wastewater treatment.

Background technique

The so-called high-concentration refractory organic wastewater refers to organic wastewater that is difficult to degrade, has poor biodegradability, has a very small BOD ₅ /COD value, usually less than 0.2, and has high COD or high chroma. The amount of water is not very large, but the pollution load is very large, and it is difficult to achieve the expected degradation effect by using traditional biological methods. Its main source is the production wastewater of papermaking, dyestuff, pharmaceutical, oil refining, organic synthesis, pesticide production and other industries. Once this kind of wastewater enters the environmental system, it will cause extremely serious consequences, often causing irreversible damage to the environmental system.

The catalytic wet oxidation method is usually at high temperature (200-350°C) and high pressure (2-20MPa), using _O2 as the oxidant, under the action of the catalyst, oxidizes and removes organic matter in water, and finally achieves the purpose of mineralization. This technology has developed rapidly in foreign countries. Since the 1970s, Japan has successively established wet catalytic devices to treat various organic wastewater, such as Japan's Mitsubishi Petrochemical Company to treat ethylene production wastewater washing liquid, and its operating conditions: 200 ° C, 3.45 MPa , stay for 60 minutes, the treatment capacity is 120m ³ /d, the influent COD is 7.5-15g/L, and the COD removal rate is 67%-80%. Japan Kawasaki Asahi Chemical Company treats acrylocyanide production wastewater, and its operating conditions are: 250°C , 7MPa, stay for 90 minutes, the treatment capacity is 790m ³ /d, the influent COD is 37-46g/L, the effluent COD is 14.8-16.1g/L, and the COD removal rate is 60%-65%. From the 1980s to the 1990s, there were many research reports, and the technology is still being researched and deepened. Du Hongzhang from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Yin Chenglong from the Anshan Coking Refractory Design Institute of the Ministry of Metallurgy published research results on the treatment of refractory high-concentration organic wastewater by catalytic wet oxidation in 1997. For details, see "Water Treatment Technology", Du Hongzhang, published in June 1997, "wet catalytic purification technology for refractory high-concentration organic wastewater". The main reactor in this study is made of TA3 titanium steel, the design pressure is 12MPa, the operating temperature is less than 350°C, the inner diameter of the reactor is 16mm, and the length is 500mm. The equipment used in the process includes air bottles, pressure gauges, front pressure controllers, gas regulating valves, mass flow meters, water metering tubes, etc. Wastewater treatment steps: The oxidant gas (air) comes from the steel cylinder, adjusted to the required pressure through the front pressure controller, mixed with the raw water from the high trace feed pump after passing through the mass flow meter and preheated, and then enters from the bottom of the reactor Reactor, the top and bottom of the reactor are filled with ceramic particles, and the middle is filled with catalysts. The bed height is about 7.5cm. The reacted materials come out from the upper end of the reactor, and are cooled and separated by the condenser and separator in turn, and the liquid enters the water storage Sampling and analysis during the tank, the gas is vented through the rear pressure regulator and the exhaust gas flowmeter. The optimum process conditions for the reaction are 270℃, 9.0MPa, 6.2L/h air volume, and 2.0h ^-1 feed space velocity. The disadvantages of this process: (1) the reaction must be carried out at 270 ° C and 9.0 MPa to obtain satisfactory results; (2) the price of the self-made catalyst is expensive; (3) the waste water is in direct contact with the reactor, which is easy to damage the reactor materials cause corrosion.

As a kind of electromagnetic wave, microwave is known as one of the greatest inventions of the 20th century. Compared with conduction heating, microwave has the characteristics of fast heating speed, high heating efficiency, uniform heating, and temperature diffusion from the inside to the outside of the object. A large number of studies have shown that for chemical reactions, microwaves have non-thermal effects in addition to thermal effects. The alternating electric field and magnetic field of the microwave hundreds of millions of times per second will strongly oscillate the chain structure of the macromolecular organic matter, causing it to be destroyed and broken, forming a small molecular structure, and then catalyzed and oxidized, and finally decomposed into CO ₂ and H ₂ O.

In recent years, microwaves have been widely used in the field of wet catalytic oxidation, such as "Technology and Device for Microwave Catalytic Oxidation Treatment of Refractory Organic Wastewater" <Patent No.> 02118708.8 invented by Quan Xie, Xue Daming, Zhao Yazhi, etc. of Dalian University of Technology. The processes in this study include: grid removal, flocculation settling, catalytic oxidation and steam condensation. Catalytic oxidation is carried out in a microwave reactor. The optimal process conditions are: the ratio of oxidant mass to wastewater COD mass is 1.0-20%, the temperature is lower than 100°C, the residence time is 4-17min, and the wastewater COD removal rate is about 95%. . The disadvantages of this process are: (1) due to the microwave radiation of waste water under normal pressure, the temperature of waste water can easily reach the boiling point, which will cause a lot of energy waste due to vaporization; (2) the reaction temperature can only reach 100 ℃, from the perspective of chemical reaction kinetics, there is a limit to the chemical reaction speed.

Contents of the invention

The purpose and task of the present invention will solve the problems existing in the existing wet catalytic oxidation technology: (1) must react under high temperature (200～350°C) and high pressure (2～20MPa), and the reaction conditions are relatively harsh, so the requirements for equipment Higher and increased construction costs; (2) The catalyst is expensive, and it is easy to be poisoned or lost during use, resulting in high water treatment costs, which are unbearable for enterprises; (3) Since the treated water is high-concentration organic wastewater, It is easy to cause corrosion to the reactor, especially the pressure vessel, which is easy to cause safety hazards; (4) microwave-assisted catalytic oxidation under normal pressure is easy to vaporize the water body, resulting in energy waste; From the perspective of scientific analysis, the problem of increasing the reaction rate is limited, and a method and device for treating high-concentration refractory organic wastewater with microwave heating and low pressure at a reaction system temperature of 110°C to 200°C and a pressure of 0.3 to 1.6MPa are provided. Technical solution of the present invention.

The basic concept of the present invention is a new water treatment method and device combining microwave electromagnetic energy propagation technology and pressure vessel, applying a certain pressure on the reaction system, which can increase the reaction temperature and ensure that the reaction is in the liquid phase It fully embodies the advantages of microwave "non-thermal effect" - fast degradation speed, high degradation efficiency, high energy utilization rate, and equipment is not easy to be corroded. The thermal and non-thermal effects of microwaves are used to make organic pollutants undergo multiple low-pressure cycle oxidation reactions in the presence of catalysts and oxidants.

The method for microwave heating and low-pressure treatment of high-concentration refractory organic wastewater proposed by the present invention mainly includes microwave radiation, catalytic oxidation, effluent discharge or reuse, degradation and residence time, and is characterized in that the catalytic oxidation treatment of wastewater [1] is It is carried out in a batch-type microwave reactor [3], and its water inlet and outlet are completed by a liquid phase pipeline [11]; the temperature in the microwave reactor [3] is set between 110 ° C and 200 ° C, The pressure is set at 0.3MPa～1.6MPa; the treated wastewater [1] is toxic and harmful organic wastewater with high concentration and difficult to be degraded by biological methods, and its COD value is between 3000～200000mg/L; during the treatment process, oxygen or air is used as the The main oxidant, the gas phase pipeline [10] in the microwave reactor [3] is equipped with an aeration head [27] at the end, and the oxidant is charged into the microwave reactor [3] through the gas phase pipeline [10] from the high-pressure gas cylinder [9] , the aeration head[27] is always aerating under pressure inside the liquid surface during the degradation reaction; the catalyst used is an activated carbon catalyst that can float on the surface of the liquid after flotation in water, and the dosage is 1/2 of the weight of the water body 4% to 30%; the treatment process adopts the cyclic oxidation method, and the number of cycles is 1 or 3 times, through microwave radiation, catalytic oxidation, and cooling after being discharged from the microwave reactor [3]; and then reintroduced into the microwave reactor [3] , and then microwave radiation, catalytic oxidation, cooling after being discharged from the microwave reactor [3], and so on; when the COD concentration of wastewater is below 10000mg/L, one-time treatment can be used; When the COD concentration of wastewater [1] is greater than 10000mg/L, the oxidation treatment is carried out 3 times; when the COD concentration is greater than 10000mg/L, the method steps are as follows:

In the first step, the waste water [1] is divided into two groups, and one group is introduced into the liquid carrier [28] of the microwave reactor [3]. , the other group is temporarily stored in the water tank A[2], and its volume should also be 3/4 of the volume of the liquid carrier [28], to be introduced into the microwave reactor [3];

In the second step, all liquid phase valves are closed, and only the high-pressure cylinder valve [13] is opened to pressurize the microwave reactor [3];

In the third step, when the pressure gauge [31] reaches the set pressure, the microwave generator [8] is started, and the water sample in the reactor starts to heat up;

In the fourth step, when the water temperature reaches the set temperature, turn off the microwave generator [8];

The fifth step, after that, the water body stays in the microwave reactor [3] for 3 to 10 minutes, then close the valve of the high-pressure gas cylinder [13], open the water outlet valve [15] and rely on the air pressure inside the microwave reactor [3] to pass the waste water through The liquid phase pipeline [11] is discharged, and after being cooled in the cooling device [4], it flows to the water tank B [5], and the internal air pressure of the microwave reactor [3] is evacuated;

The sixth step is to open the water inlet valve [14] again, and introduce the waste water [1] retained in the water tank A [2] into the microwave reactor [3]; at the same time, the cooled waste water can be passed from the water tank B [5] through the pipeline Between the valve [16], it is temporarily stored in the water tank A [2] to complete the first cycle oxidation process;

The seventh step is to repeat the above-mentioned second to sixth steps to complete the second cyclic oxidation process, and then repeat the above-mentioned second to sixth steps to complete the third cyclic oxidation process;

In the eighth step, after the above-mentioned three cycles of oxidation, the treated waste water is discharged or recovered through the drain valve [17] [6].

Realize the device that the microwave heating low-pressure treatment high-concentration refractory organic waste water that the method of the present invention adopts adopts, in by microwave generator [8], microwave reactor [3], microwave generator waveguide [7], microwave reactor control system [32], high-pressure gas cylinder [9], water tank, cooling device [4], discharge or recovery [6] in the wastewater treatment system, the microwave reactor [3] used is a closed pressure vessel, through microwave Irradiation degrades waste water. It is composed of stainless steel jacket [21] and reactor head [19]. Its shape is a cylindrical structure, mainly including stainless steel jacket [21], insulation layer [25], [20], carrier platform [28], reactor waveguide [22], high pressure resistant glass window [23], it is characterized in that: the reactor waveguide [22] is made from the autoclave body [20] and the stainless steel jacket The side of [21] extends into the cavity of the microwave reactor [3], and its end is equipped with a high-pressure resistant glass window [23], facing the liquid carrier [28], and is connected by a glass sealing gasket [24] The reactor waveguide [22] is sealed, and the other end of the reactor waveguide [22] is welded with a flange [12]; the reactor head [19] is a cylindrical stainless steel kettle cover, and the microwave reactor head [19] The bottom is conical, and the top is equipped with a gas phase pipeline [10], a thermocouple [29], a liquid phase pipeline [11], a pressure gauge [31], an automatic pressure relief solenoid valve [33], and a reactor head [19] ] and the autoclave body [20] are tightened with bolts, and the head sealing gasket [30] is clamped in the middle; in the cavity of the autoclave body [20] of the microwave reactor [3], there is a loading The liquid stage [28], the liquid stage [28] is a drum-shaped structure, placed in the center of the bottom of the cavity of the microwave reactor, and its thermocouple [29], gas phase pipeline [10] and liquid phase pipeline [11], They all protrude from the barrel mouth of the upper part of the liquid carrier, which is close to the bottom; a water and gas exhaust pipe [26] is provided at the bottom of the autoclave body [20] cavity of the microwave reactor [3], and is equipped with a reaction valve at the bottom of the device [18].

A further feature of the microwave heating and low-pressure treatment device for high-concentration refractory organic wastewater adopted in the present invention is that a rectangular opening is provided on the side of the autoclave body [20] and the stainless steel jacket [21], and the microwave generator waveguide [ 7] and the reactor waveguide [22] guide the microwave into the microwave reactor [3], and the two waveguides are connected in a straight line with flanges [12], and the high-pressure resistant glass window [23] directly extends into the microwave reactor [ 3] inside the cavity, and facing the liquid carrier [28]; the sealing gasket [30] and the glass sealing gasket [24] in the microwave reactor [3] are made of polytetrafluoroethylene material, sealed The adhesive used is 704 adhesive; the liquid carrier [28] in the microwave reactor [3] is made of high-temperature-resistant, high-pressure-resistant and wave-permeable materials, such as glass, ceramics and plastics, and the waste water [1] is The liquid phase pipeline [11] is introduced into the liquid carrier [28], and then subjected to microwave degradation treatment; the tail of the gas phase pipeline [10] in the microwave reactor [3] is equipped with an aeration head [27]. The air head [27] performs pressurized aeration inside the liquid surface, and the aeration flow rate is 0.03-0.07m ³ /h.

In the wastewater treatment process, the floating solid catalyst is placed in the liquid carrier [28] of the microwave reactor [3] in advance, and the wastewater is introduced into the liquid carrier [28] through the water tank A [2] through the liquid phase pipeline [11]. , the volume of wastewater should be about 3/4 of the volume of the liquid carrier [28]; the catalyst floats on the surface of the liquid, and then undergoes subsequent degradation treatment. After a period of work, when the treatment efficiency drops by 15-30%, it indicates that the activity of the catalyst is reduced, and it can be placed in a microwave reactor [3] for microwave regeneration or replaced.

The relation of each parameter involved in the present invention should be like this: according to the difference of waste water COD concentration, adopt different technological parameters correspondingly, as reaction temperature, reaction pressure, catalyst dosage, residence time, aeration flow rate, generally with The greater the COD concentration of the wastewater, the closer the selection of its process parameters is to the upper limit of the parameter range, otherwise the lower limit is selected.

Matters needing attention when adopting method device of the present invention to carry out waste water treatment:

(1) Before starting the device, check the integrity of instruments, equipment and pipelines and whether there is any leakage at the connection;

(2) The wastewater treatment system can only be started after the above-mentioned inspection results are qualified.

Main advantage of the present invention: (1) utilize microwave radiation to process, because the thermal effect of microwave and non-thermal effect work simultaneously, so organic matter degradation speed is fast, efficiency is high, improves 20%～40% than existing conduction heating method; ( 2) The treatment is carried out under relatively low temperature and low pressure conditions, which reduces the load of air pressure on the material of the container; (3) the use of pressure aeration method not only further increases the oxidation efficiency, but also plays a stirring role, which can completely replace the existing method The magnetic stirrer in it can save 15% of equipment investment cost; (4) The equipment is not easy to be corroded. Since the organic wastewater is contained in the liquid carrier and receives microwave radiation, the wastewater does not directly contact with the metal material, which greatly reduces the waste water. The corrosion of the container prolongs the service life of the equipment by 2 to 3 times.

Schedule description:

The present invention establishes 7 attached tables altogether, and further illustrates the details of the present invention in conjunction with the attached tables.

Table 1 is a table of hazard levels for pressure vessels classified according to internal pressure

Its content is that, according to different pressure working conditions, "Pressure Vessel Safety Manual" is divided into four grades, and the working pressure of 0-1.6MPa belongs to the type of low pressure vessel, which is relatively the safest. Therefore, the upper limit of the working pressure of the present invention is It is 1.6MPa.

Table 2 is the saturated vapor pressure table of water in the temperature range of 140°C to 200°C

Its content is to ensure that the water body does not boil when the water is at a high temperature (over 100 ° C), and the partial pressure gauge formed by the water vapor in the airtight container. The upper limit of pressure corresponding to 200°C is 1.55MPa, so the upper limit of the working temperature of the present invention is 200°C, which is very safe.

Table 3 is the comparison result table of the effect of different types of activated carbon catalysts on the COD removal rate of experimental wastewater

The content is that, through the comparison of the effects of different types of activated carbon on the COD removal rate, floating carbon has the best effect because of its larger specific surface area, looser carbon, smaller specific gravity, and relatively stronger adsorption.

Table 4 Oxygen aeration flow rate for the detection results table of experimental wastewater COD removal rate

Table 5 Air aeration flow rate for the detection results table of experimental wastewater COD removal rate

In conjunction with table 4, 5 illustrates: (1) if do not need aeration process, promptly aeration flow rate is 0, and the removal rate of COD is relatively very low, is respectively 54% and 56.3%; (2) as long as add a small amount of aeration, COD The removal rate of COD increases significantly, because the aeration directly "adds" the oxidant inside the liquid surface; (3) The size of the aeration flow has no significant difference in the removal rate of COD, increasing from 0.03m ³ /h to 0.07m ³ /h, the flow rate has more than doubled, but the COD removal rate has only increased by a few percentage points; (4) The comparison effect of air aeration and oxygen aeration is almost the same, and air can be used as an oxidant instead of pure oxygen in actual treatment work.

Table 6 is the relationship between COD removal rate and time of distillation wastewater of xx refinery

Its content is that in the process of treatment and degradation, the waste water is first irradiated with 660w microwave, and when the water temperature reaches 150°C, the microwave power is adjusted to 200w and the timer is started, and the water will maintain this temperature at this time. In 8 minutes after timing, the reaction speed is quite fast, and the COD degradation efficiency is also very high (67%～69%). After 8 minutes, the COD degradation efficiency hardly increases, and the COD degradation efficiency in 35 minutes is about 67%, and 8 The degradation efficiencies at minutes are about the same. Therefore, the process only uses the first few minutes of the fastest degradation efficiency for treatment, which is also an important basis for recycling process treatment.

Table 7. xx chemical plant sodium nitrophenolate synthetic wastewater COD removal rate test results table

It can be seen from the processing data in Table 7 that the treatment of high-concentration refractory real wastewater (COD concentration between 10,000 mg/L and 200,000 mg/L) by this method has the following characteristics: (1) The removal rate of a single cycle is not high, only There are 40～70%; It can be found that the removal rate of each group is investigated separately, and the removal rate increases with the decrease of the COD concentration of the water sample, that is, the COD removal rate of the relatively dilute solution is higher; (3) similar to "radioactive element half-life period "effect, three cycles are adopted in the method, each cycle will reduce the COD concentration of raw water by more than half, and the total removal rate can be expressed by the following formula:

η _total = 1-(1-η ₁ )(1-η ₂ )...(1-ηn)

_ηtotal : the total removal rate, ηn: the removal efficiency of a single group of cycles, n: the number of cycles combined with the actual application situation, n is 3 as the best; (4) This method does not pursue "one-step completion", but adopts stages cyclic oxidation treatment.

Description of drawings:

The present invention is provided with 6 accompanying drawings altogether, Fig. 1 is a schematic diagram of the process flow of the present invention, Fig. 2 is a schematic diagram of the overall plane layout relationship structure of the device of the present invention, Fig. 3 is a schematic diagram of a microwave reactor front view sectional structure of the present invention, and Fig. 4 is Fig. 3 is a top view structural schematic diagram, Fig. 5 is a floating activated carbon SEM figure, and Fig. 6 is an ordinary activated carbon SEM figure, now in conjunction with the accompanying drawings, further illustrate the details of the present invention.

Fig. 1 is a schematic diagram of the process flow of the present invention

Process flow of the present invention is carried out by following steps (COD concentration is at 10～200g/L):

In the first step, the waste water [1] is divided into two groups, one group is directly introduced into the microwave reactor [3] through the water tank A [2] to be treated, and the other group is introduced into the water tank A [2] for temporary storage;

In the second step, the waste water in the microwave reactor [3] is degraded and reacted. After staying for a specified reaction time, the waste water in the microwave reactor is put into the cooling device [4], and then enters the water tank B [5] after cooling;

In the third step, after the wastewater in the microwave reactor [3] is released, another group of wastewater temporarily stored in the water tank A [2] is introduced into the microwave reactor [3] for degradation. During the degradation process, the The waste water of water tank B [5] is introduced into water tank A [2] for temporary storage;

The fourth step is to repeat the above first step to the third step to complete a cycle of oxidation;

In the fifth step, after 3 cycles of oxidation reactions from the first step to the fourth step above, the organic waste water will be greatly degraded. At this time, the waste water in the water tank B [5] will be finally discharged or recycled [6]. The arrows in the figure indicate the direction in which the waste water flows through the pipeline.

It should be noted that: when the COD concentration is less than 10000mg/L, it is not necessary to circulate the treatment, and the waste water [1] can be discharged after one-time treatment by the microwave reactor [3].

Fig. 2 is a structural schematic diagram of the overall plane layout relationship of the device of the present invention

The figure shows that the microwave reactor [3] has a rectangular opening from the side, through the waveguide [7] of the microwave generator [8] and the waveguide [22] of the microwave reactor [3] with the same cross-sectional size, The microwave generator [3] is connected with the flange [12]; the microwave reactor [3] top is connected with a gas phase pipeline [10] and a liquid phase pipeline [11], and the gas phase pipeline [10] passes through the high-pressure cylinder valve [13] and The high-pressure gas cylinder [9] is connected; the liquid phase pipeline [11] is a pipeline that divides two branches through the water inlet valve [14] and the water outlet valve [15], and the water tank A [2] and the water tank B [5] ] connection; there is a cooling device [4] between the water tank B[5] and the water outlet valve [15]; the valve between the pipelines [16] is between the water tank A[2] and the water tank B[5]; the water tank B[5] Finally discharge or recover [6] through the drain valve [17]. The control of each valve is manually operated, the solid line arrow direction indicates the direction of waste water flow, the dotted line arrow is the air intake direction, and the symbol [1] is waste water.

Fig. 3 is the schematic diagram of the front view sectional structure of the microwave reactor of the present invention

The microwave reactor is cylindrical in shape, including a stainless steel jacket[21], an insulation layer[25], an autoclave body[20], a liquid carrier[28], a reactor waveguide[22], and a high-pressure glass window[23] ], and the autoclave body [20] is placed in the insulation layer [25], and the insulation layer [25] is placed inside the stainless steel jacket [21]; the liquid carrier [28] is placed in the inner cavity of the autoclave body [20] ; The top of the reactor head [19] is equipped with liquid phase pipeline [11], gas phase pipeline [10], pressure gauge [31], temperature measuring thermocouple [29] and automatic pressure relief solenoid valve [33]; thermocouple [ 29] and the automatic pressure relief solenoid valve [33] are monitored by the microwave reactor control system [32]; the waste water is introduced into the liquid carrier [28] by the liquid phase pipeline [11], and then undergoes microwave degradation treatment; the reactor seal The bottom of the head [19] is a conical design; the bottom of the microwave reactor is connected to a water-gas exhaust pipe [26] and a valve [18] at the bottom of the reactor. There is an aeration head [27] at the end of the gas phase pipeline [10] in the microwave reactor, and the aeration head [27] is always aerating under pressure inside the liquid surface during the degradation reaction process. Symbol [24] is the glass sealing gasket, and symbol [30] is the head sealing gasket. It should be noted that the pipelines and instruments installed on the top of the reactor head [19] are not on the same section, but for the sake of clarity, they are specially shown on the same section, and the reactor head and the autoclave body are fixed at the same time For the sake of clarity, the bolts are not fully shown, and are explained here.

Fig. 4 is a top view structural schematic diagram of Fig. 3

A gas phase pipeline [10] is installed at the center of the reactor head [19], and a pressure gauge [31], a thermocouple [29], a liquid phase pipeline [11] and an automatic pressure relief solenoid valve [33] are respectively installed in the gas phase Around the pipeline [10]; the reactor waveguide [22] has a rectangular cross-section and extends into the cavity from the side of the microwave reactor.

Figure 5 is the SEM image of floating activated carbon

Figure 6 is the SEM image of ordinary activated carbon

From Figure 5 and Figure 6, two groups of activated carbon pictures, enlarged by 1000 times, it can be seen that the surface of floating activated carbon is obviously more wrinkled and looser than that of ordinary activated carbon, which fully demonstrates that floating activated carbon has a larger specific surface area and relatively higher adsorption capacity. stronger.

Detailed ways:

In order to research and test the method of the present invention, a set of small-scale test equipment has been specially processed, and the external dimensions of this device are: a height of 50cm, an external diameter of 40cm, and a cavity internal volume of 5L; the length of the waveguide is 12cm, and the cross-sectional dimension is 90×45mm; the size of the quartz glass window is Φ120×18mm; the liquid carrier [28] uses a standard 500ml glass beaker. The actual wastewater is inspected to investigate whether the method and device have a significant degradation effect on the COD removal rate of high-concentration refractory organic wastewater, and will now be described with specific implementation methods.

Example 1

xx oil refinery production wastewater treatment

The distillation waste water retrieved from the xx refinery has a small amount of sundries in the water, which is relatively transparent but has a strong pungent smell. Its specific implementation steps are as follows:

Preparation:

First of all, sampling analysis, using the potassium dichromate method to measure the COD value of the water sample, the COD content is about 3000mg/L;

Secondly, the selection of process parameters: water volume 400ml, reaction temperature 110°C, pressure 0.3MPa, residence time in microwave reactor [3] for 3 minutes, select floatable activated carbon catalyst, dosage is 4% of water body weight, The aeration flow rate is 0.03m ³ /h, and since the COD concentration is less than 10000mg/L, one-time degradation treatment is adopted;

The processing steps are:

In the first step, 400ml of waste water is taken and introduced into the microwave reactor [3]. The catalyst is acid-washed, alkali-washed and activated activated carbon (floatable), and the dosage is 4%;

The second step is equipment inspection: power supply system, microwave system leakage, microwave reactor [3] related parts sealing, equipment safety, leakage;

The third step is to seal the reactor after checking that all aspects are qualified, open the high-pressure gas cylinder valve [13] to carry out pressurized aeration, and when the pressure gauge [31] shows that the internal pressure of the reactor reaches 0.3MPa, start the microwave generator [8 ] for degradation, the input power of microwave is 660w;

In the fourth step, when the wastewater rises from room temperature to 110°C, turn off the microwave and close the air valve;

The fifth step, after staying for 3 minutes, open the water outlet valve [15] to discharge the waste water by the pressure inside the reactor, and discharge it into the water tank B [5] after passing through the cooling device [4], and then release the pressure in the reactor;

The sixth step is to shut down and turn off the microwave power supply;

In the seventh step, the quality of the effluent is tested, and the COD value of the effluent is also measured by the potassium dichromate method, and the COD removal rate is calculated. Under this process condition, the effluent COD removal rate is 87%.

Example 2

xx chemical plant production wastewater treatment

The water sample taken from the xx chemical plant is the synthetic wastewater of sodium p-nitrophenolate. The water quality is pink, clear and transparent. The specific implementation steps are as follows:

Preparation:

First of all, sampling analysis, using the potassium dichromate method to measure the COD value of the water sample, the COD content is about 200000mg/L;

Secondly, the selection of process parameters: treatment water volume 800ml, reaction temperature 200°C, pressure 1.6MPa, residence time in microwave reactor [3] for 10 minutes, select floatable activated carbon catalyst, dosage is 30% of water body weight , aeration flow rate 0.07m ³ /h, cycle oxidation 3 times;

The processing steps are:

The first step is to take 400ml of waste water and directly introduce it into the microwave reactor [3] through the water tank A[2], and then take 400ml of waste water into the water tank A[2] for temporary storage. The catalyst is activated carbon that has been acid-washed, alkali-washed and activated (can float), the dosage is 30%;

The second step is equipment inspection: power supply system, microwave system leakage, microwave reactor [3] related parts sealing, equipment safety, leakage;

The third step is to seal the reactor after checking that all aspects are qualified, open the high-pressure gas cylinder valve [13] to carry out pressurized aeration, and when the pressure gauge [31] shows that the internal pressure of the reactor reaches 1.6MPa, start the microwave generator [8 ] for degradation, the input power of microwave is 660w;

In the fourth step, when the wastewater rises from room temperature to 200°C, turn off the microwave and close the air valve;

The fifth step, after staying for 10 minutes, open the water outlet valve [15] to discharge the waste water by the pressure inside the reactor, and discharge it into the water tank B [5] after passing through the cooling device [4], and then release the pressure in the reactor;

In the sixth step, the waste water in the water tank A[2] is introduced into the reactor for treatment, and the waste water in the water tank B[5] enters the water tank A[2] again, and the waste water is recycled 3 times according to the third to fifth steps above , to complete the whole process;

The seventh step is to shut down and turn off the microwave power supply;

In the eighth step, the quality of the effluent is tested, and the potassium dichromate method is also used to measure the COD value of the effluent, and the COD removal rate is calculated. Under this process condition, the removal rate of effluent COD is 90.5%.

Implementation-related data are included in Table 7.

Schedule:

Table 1. Hazardous source levels of pressure vessels classified by internal pressure pressure vessel type low pressure container medium pressure vessel high pressure vessel ultra-high pressure vessel Pressure (MPa) 0～1.6MPa 1.6～10MPa 10～100MPa Above 100MPa

Table 2. Saturated vapor pressure table of water in the temperature range of 140°C to 200°C Pressure (MPa) 0.36 0.47 0.61 0.79 1.0 1.26 1.55 temperature(℃) 140 150 160 170 180 190 200

Table 3. Comparison of the effect of different types of activated carbon catalysts on the COD removal rate of experimental wastewater Sample serial number Activated carbon type COD removal rate (%) 123456 Floating charcoal Sinking charcoal Columnar charcoal Powder charcoal Coconut shell spherical charcoal 84.2782.878.369.381.379.4

Table 4. Test results of oxygen aeration flow rate for COD removal rate of experimental wastewater Sample serial number Flow(m ³ /h) COD removal rate (%) 123456 00.030.040.050.060.07 5483.158888.89192

Table 5. Test results of air aeration flow rate for COD removal rate of experimental wastewater Sample serial number Flow(m ³ /h) COD removal rate (%) 123456 00.030.040.050.060.07 56.386.5287.388.889.189.1

Table 6. xx Refinery Distillation Wastewater COD Removal Rate and Time Relationship Table Response time min COD removal rate (%) 0578101520253035 54.351.3267.86969706868.36667

Table 7. xx chemical plant sodium nitrophenolate synthetic wastewater COD removal rate test results table Cycles Influent COD(mg/L) Effluent COD(mg/L) COD removal rate (%) Total removal rate (%) one two three 20000011400052440 1140005244018870 435664 90.5

Claims (6)

1. The method for microwave heating and low-pressure treatment of high-concentration refractory organic wastewater, mainly including microwave radiation, catalytic oxidation, effluent discharge or reuse, degradation and residence time, characterized in that: (a) The catalytic oxidation treatment of wastewater [1] is carried out in a batch-type microwave reactor [3], and its water inlet and outlet are completed by a liquid phase pipeline [11]; (b) The temperature in the microwave reactor [3] is set between 110°C and 200°C, and the pressure is set at 0.3MPa to 1.6MPa; (c) The treated wastewater [1] is toxic and harmful organic wastewater that is difficult to degrade by high-concentration biological methods, and its COD value is between 3,000 and 200,000 mg/L; (d) Oxygen or air is used as the main oxidant during the treatment process. The gas phase pipeline [10] in the microwave reactor [3] is equipped with an aeration head [27] at the end, and the high pressure gas cylinder [9] passes through the gas phase pipeline [10] The oxidant is charged into the microwave reactor [3], and the aeration head [27] is always aerated under pressure inside the liquid surface during the degradation reaction; (e) The catalyst used is an active carbon catalyst that can float on the surface of the liquid through flotation in water, and the dosage is 4% to 30% of the weight of the water body; (f) The treatment process adopts the cyclic oxidation method, the number of cycles is 1 or 3 times, through microwave radiation, catalytic oxidation, and cooling after being discharged from the microwave reactor [3]; reintroduction into the microwave reactor [3], and then microwave Irradiation, catalytic oxidation, cooling after being discharged from the microwave reactor [3], etc., and so on; when the COD concentration of the wastewater is below 10,000mg/L, one-time treatment is used; when the COD concentration of the wastewater is 10,000mg/L-200,000mg/L Oxidation treatment is carried out in 3 cycles; (g) Wastewater [1] When the COD concentration is greater than 10000mg/L, carry out 3 cycles of treatment, the method steps are: In the first step, the waste water [1] is divided into two groups, and one group is introduced into the liquid carrier [28] of the microwave reactor [3]. , the other group is temporarily stored in the water tank A[2], and its volume should also be 3/4 of the volume of the liquid carrier [28], to be introduced into the microwave reactor [3]; In the second step, all liquid phase valves are closed, and the high-pressure cylinder valve [13] is opened to pressurize the microwave reactor [3]; In the third step, when the pressure gauge [31] reaches the set pressure, the microwave generator [8] is started, and the water sample in the reactor starts to heat up; In the fourth step, when the water temperature reaches the set temperature, turn off the microwave generator [8]; The fifth step, thereafter, the water sample stays in the microwave reactor [3] for 3 to 10 minutes, then closes the high-pressure gas cylinder valve [13], and opens the water outlet valve [15] to drain the waste water by the air pressure inside the microwave reactor [3]. It is discharged through the liquid phase pipeline [11], after being cooled by the cooling device [4], it flows to the water tank B [5], and the internal air pressure of the microwave reactor [3] is evacuated; The sixth step is to open the water inlet valve [14] again, and introduce the waste water [1] retained in the water tank A [2] into the microwave reactor [3]; at the same time, the cooled waste water can be passed from the water tank B [5] through the pipeline Between the valve [16], it is temporarily stored in the water tank A [2] to complete the first cycle oxidation process; The seventh step is to repeat the above-mentioned second to sixth steps to complete the second cyclic oxidation process, and then repeat the above-mentioned second to sixth steps to complete the third cyclic oxidation process; In the eighth step, after the above-mentioned three cycles of oxidation, the treated waste water is discharged or recovered through the drain valve [17] [6]. 2. Microwave heating and low-pressure treatment of high-concentration refractory organic wastewater, which consists of microwave generator [8], microwave reactor [3], microwave generator waveguide [7], microwave reactor control system [32], high-pressure In the wastewater treatment system composed of gas cylinders [9], water tanks, cooling devices [4], discharge or recovery [6], the microwave reactor [3] used is a closed pressure vessel, which degrades wastewater by microwave irradiation , which is composed of stainless steel jacket[21] and reactor head[19]. Liquid table [28], reactor waveguide [22], high pressure resistant glass window [23], characterized in that: (a) The reactor waveguide [22] with a rectangular cross-section extends into the cavity of the microwave reactor [3] from the side of the autoclave body [20] and the stainless steel jacket [21]. The high-pressure glass window [23] is opposite to the liquid carrier platform [28], and is sealed with the reactor waveguide [22] by the glass sealing gasket [24], and the other end of the reactor waveguide [22] is welded with a flange [ 12]; (b) The reactor head [19] is a cylindrical stainless steel kettle cover, and the bottom of the microwave reactor head [19] is a conical design, and the top is equipped with a gas phase pipeline [10], a thermocouple [29], a liquid phase The pipeline [11], the pressure gauge [31] and the automatic pressure relief solenoid valve [33], the reactor head [19] and the autoclave body [20] are tightened with bolts, and the head sealing gasket is sandwiched between them [30]; (c) In the cavity of the autoclave body [20] of the microwave reactor [3], a liquid carrier [28] is provided, and the liquid carrier [28] is a drum-shaped structure, placed in the cavity of the microwave reactor At the center of the inner bottom, its thermocouple [29], gas phase pipeline [10] and liquid phase pipeline [11] all protrude from the barrel mouth on the upper part of the liquid carrier, which is close to the bottom position; (d) A water and gas exhaust pipe [26] is provided at the bottom of the cavity of the autoclave [20] of the microwave reactor [3], and a valve [18] at the bottom of the reactor is provided. 3. The device for microwave heating and low-pressure treatment of high-concentration refractory organic waste water according to claim 2, characterized in that: there is a rectangular opening on the side of the autoclave body [20] and the stainless steel jacket [21], and microwave The generator waveguide [7] and the reactor waveguide [22] guide the microwave into the microwave reactor [3], and the two waveguides are connected by a flange [12] in a straight line, and the high-pressure resistant glass window [23] directly extends into the cavity of the microwave reactor [3], and facing the carrier platform [28]. 4. The device for microwave heating and low-pressure treatment of high-concentration refractory organic wastewater according to claim 2, characterized in that: the head sealing gasket [30] and the glass sealing gasket [24] in the microwave reactor [3] ] The material is polytetrafluoroethylene, and the sealant is 704 adhesive. 5. According to the device for microwave heating and low-pressure treatment of high-concentration refractory organic wastewater described in claim 2, it is characterized in that: the liquid carrier [28] in the microwave reactor [3] adopts high-temperature-resistant, high-pressure-resistant wave-transparent It is made of materials with good properties, such as glass, ceramics and plastics. The waste water [1] is introduced into the liquid carrier [28] through the liquid phase pipeline [11], and then undergoes microwave degradation treatment. 6. According to the device of microwave heating and low-pressure treatment of high-concentration refractory organic wastewater described in claim 2, it is characterized in that: the tail of the gas phase pipeline [10] in the microwave reactor [3] is equipped with an aeration head [27], During the degradation reaction process, the aeration head [27] performs pressurized aeration inside the liquid surface, and the aeration flow rate is 0.03-0.07m ³ /h.

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