1. A safe, energy-saving and efficient 'three-high' wastewater treatment process is characterized by comprising the following steps:

(1) preheating waste water;

(2) mixing and heating the waste water and the air;

(3) carrying out wet catalytic oxidation on the wastewater;

(4) recovering and separating the energy of the treated water;

wherein, the step (3) adopts air as an oxidant, and under the action of a ruthenium catalyst, the pH value of the reaction is controlled to be 7-9, the reaction temperature is controlled to be 200-220 ℃, the reaction pressure is controlled to be 4.0-6.0 Mpa, and the catalytic oxidation is carried out in a reactor;

and (4) preheating the wastewater to be treated by using the treated water as a heating medium, realizing heat exchange between the treated water and the wastewater to be treated, and then carrying out gas-liquid separation on the treated water.

2. The safe, energy-saving and efficient 'three-high' wastewater treatment process as claimed in claim 1, wherein the step (1) is specifically as follows: the wastewater to be treated is preheated by using a heat exchanger, the wastewater to be treated is introduced into a cold cavity of the heat exchanger, and the treatment water is introduced into a hot cavity of the heat exchanger.

3. The safe, energy-saving and efficient 'three-high' wastewater treatment process as claimed in claim 1, wherein the step (2) is specifically as follows: and (3) increasing the air pressure by using a compressor, then injecting the preheated wastewater and the compressed air into a pre-reactor by using an injector to perform pre-reaction, and then mixing and heating by using a heater.

4. A safe, energy-saving and efficient "three-high" wastewater treatment process as claimed in claim 3, wherein the theoretical injection quantity a of the compressed air in the step (2) is calculated according to the following formula:

a ═ 4.3COD, where COD represents the chemical oxygen demand for wastewater degradation.

5. A safe, energy-saving and efficient 'three-high' wastewater treatment process as claimed in claim 3, wherein the pressure difference of an air filter of the compressor is controlled to be 150-1200 Pa in the step (2).

6. The safe, energy-saving and efficient 'three-high' wastewater treatment process as claimed in claim 3, wherein the inlet temperature of the pre-reactor in the step (2) is controlled to be 150-230 ℃, and the pressure is controlled to be 4.0-6.0 MPa.

7. The safe, energy-saving and efficient 'three-high' wastewater treatment process as claimed in claim 1, wherein the inlet temperature of the reactor in the step (3) is controlled to be 150-230 ℃.

8. The safe, energy-saving and efficient 'three-high' wastewater treatment process as claimed in claim 1, wherein the outlet temperature of the reactor in the step (3) is controlled to be 200-230 ℃.

9. The safe, energy-saving and efficient 'three-high' wastewater treatment process as claimed in claim 1, wherein the reaction time of the step (3) is 0.1-2 h.

10. A safe, energy-saving and efficient "three-high" wastewater treatment process as claimed in claim 9, wherein the reaction time of step (3) is 1 h.

Background

In recent years, the industries such as petroleum, chemical industry, printing and dyeing, pharmacy and the like are rapidly developed, a large amount of high-organic matter, high-salt and high-COD three-high wastewater is generated, and great harm is brought to the ecological environment. The three-high wastewater has strong toxicity and high stability, the wastewater after the traditional advanced oxidation treatment still has the problem of poor biochemical treatment effect, and other physical and chemical methods have poor treatment effect or high treatment cost, so the treatment of the wastewater is always a well-recognized problem in the sewage treatment field. Therefore, new economic and effective processes have been studied, and specific biological methods, advanced oxidation technologies, membrane methods, etc. have been proposed, but no processes have been developed that can be used in engineering treatment practices and that have both effectiveness and economy.

The Fenton oxidation method belongs to an advanced oxidation technology, has a certain treatment effect on organic matters which are difficult to degrade in water, and still has the following defects in practical application: 1) the conventional Fenton reaction takes place in a static vessel or reaction chamber, H₂O₂The utilization rate is low, and the degradation of organic matters is incomplete; 2) the simple Fenton reaction must be at pH<3, the extremely low pH value greatly increases the water treatment cost; 3) the biochemical property of the wastewater after the Fenton reaction treatment is poor.

Disclosure of Invention

Aiming at the problem that the waste water after the traditional advanced oxidation treatment still has poor biochemical treatment effect, the invention provides a safe, energy-saving and efficient 'three-high' waste water treatment process, which adopts a wet catalytic oxidation technology to treat the 'three-high' waste water, namely, air is used as an oxidant, and process indexes such as temperature, pressure, pH value and the like are reasonably controlled under the action of a catalyst, so that the purposes of improving the removal rate of refractory organic matters and effectively reducing the waste water treatment cost are achieved.

A safe, energy-saving and efficient 'three-high' wastewater treatment process comprises the following steps:

(1) preheating waste water;

(2) mixing and heating the waste water and the air;

(3) carrying out wet catalytic oxidation on the wastewater;

(4) recovering and separating the energy of the treated water;

wherein, the step (3) adopts air as an oxidant, and under the action of a ruthenium catalyst, the pH value of the reaction is controlled to be 7-9, the reaction temperature is controlled to be 200-220 ℃, the reaction pressure is controlled to be 4.0-6.0 Mpa, and the catalytic oxidation is carried out in a reactor;

and (4) preheating the wastewater to be treated by using the treated water as a heating medium, realizing heat exchange between the treated water and the wastewater to be treated, and then carrying out gas-liquid separation on the treated water.

The pH value of the reaction is controlled to be 7-9, which is due to the following steps: when the three-high wastewater is treated, the pH value in the reaction system is reduced due to the accumulation of the intermediate carboxylic acid and then slightly increased due to the further oxidation of the intermediate, and the higher the reaction temperature is, the faster the substance is converted, and the more drastic the change of the pH value is. The method limits the reaction pH value to be 7-9, can accelerate the reaction speed and the degradation of organic matters, avoids the increase of too low pH value to the corrosion of reaction equipment and the increase of the material use cost, simultaneously prevents the active components of the catalyst caused by low pH value from dissolving out and losing, and avoids secondary pollution.

The reaction temperature is controlled to be 200-220 ℃, because: at a temperature T <100 ℃, the solubility of oxygen decreases with increasing temperature; when the temperature T is more than 150 ℃, the solubility of the organic matters is increased along with the increase of the temperature, and the mass transfer coefficient of oxygen in water is increased along with the increase of the temperature; the increase in temperature reduces the viscosity of the solution, and thus the increase in temperature facilitates mass transfer of oxygen in the liquid and oxidation of the organic matter. The higher the temperature, the more complete the oxidation of the organic. However, the temperature rises, the total pressure increases, the power consumption increases and the reactor requirements become higher. Therefore, the invention selects proper temperature within the range of 200-220 ℃ from the economic point of view according to different wastewater components and the structures of organic matters in the wastewater, thereby not only meeting the oxidation efficiency, but also reasonably considering the energy consumption cost.

The reaction pressure is controlled to be 4.0-6.0 Mpa, because: the main function of the system pressure is to maintain the presence of a liquid phase in the reaction system, and the effect on the oxidation reaction is not significant. If the pressure is too low, a large amount of heat of reaction is consumed in the evaporation of water, so that not only the reaction temperature is not guaranteed, but also the reactor is in danger of evaporation to dryness. Therefore, the reaction pressure should be controlled to be 4.0 to 6.0MPa according to the reaction temperature.

Further, the step (1) is specifically as follows: the wastewater to be treated is preheated by using a heat exchanger, the wastewater to be treated is introduced into a cold cavity of the heat exchanger, and the treated water (treated water) is introduced into a hot cavity of the heat exchanger.

Further, the step (2) is specifically as follows: and (3) increasing the air pressure by using a compressor, then injecting the preheated wastewater and the compressed air into a pre-reactor by using an injector to perform pre-reaction, and then mixing and heating by using a heater.

Further, the theoretical injection quantity A of the compressed air in the step (2) is calculated according to the following formula:

a ═ 4.3COD, where COD represents the chemical oxygen demand for wastewater degradation.

Further, in the step (2), the pressure difference of an air filter of the compressor is controlled to be 150-1200 Pa, the pressure difference of two sides of the air filter is in the range, the pressure loss before the inlet of the fan is small, the outlet pressure of the air compressor can be ensured, and on the contrary, the pressure loss before the inlet of the compressor is large, and the outlet pressure of the compressor is reduced.

Further, the inlet temperature of the pre-reactor in the step (2) is controlled to be 150-230 ℃, and the pressure is controlled to be 4.0-6.0 Mpa. When the inlet temperature is lower than 150 ℃, the activity of the catalyst is low, and organic matters in the high-concentration wastewater cannot be completely converted; when the inlet temperature is higher than 230 ℃, the system is easy to generate overpressure, and even a reactor 'steam-drying boiler' accident can occur.

Further, the inlet temperature of the reactor in the step (3) is controlled to be 150-230 ℃. In the running process of the reactor, the temperature rise of a reactor bed layer (generally about 0.6 ℃) is adjusted mainly by changing the amount of compressed air and the temperature of a reactor inlet; when the inlet temperature is lower than 150 ℃, the activity of the catalyst is low, and organic matters in the high-concentration wastewater cannot be completely converted; when the inlet temperature is higher than 230 ℃, the system is easy to generate overpressure, and even a reactor 'steam-drying boiler' accident can occur.

Further, the outlet temperature of the reactor in the step (3) is controlled to be 200-230 ℃. When the outlet temperature is lower than 200 ℃, the activity of the catalyst is low, and organic matters in the high-concentration wastewater cannot be completely converted; when the outlet temperature is higher than 230 ℃ and the pressure is lower than 4.0MPa, the system is easy to generate overpressure, and even the accident of 'steam drying boiler' of the reactor can occur.

Further, the reaction time of the step (3) is 0.1-2 h, preferably 1 h. In different applications, the reaction time can be flexibly controlled and adjusted from 0.1-2 h, compared with biological treatment, the reaction residence time of the wastewater is shortened by a lot, and compared with the traditional Fenton reaction, the method is more energy-saving and efficient.

The beneficial effect of the invention is that,

(1) compared with the conventional treatment method, the three-high wastewater treatment process provided by the invention has a wide application range, can almost indiscriminately effectively oxidize various high-concentration organic wastewater, and improves the biodegradability (B/C ratio) of the wastewater after treatment by more than 3 times;

(2) the treatment efficiency is high, the COD treatment efficiency can reach more than 90% under the conditions of proper temperature and pressure, and the treatment effect on the wastewater difficult to degrade, namely 'three high' wastewater is good;

(3) the oxidation rate is high, the reaction residence time is within 0.1-2 h, and compared with biological treatment, the reaction residence time of the wastewater is much shorter, so that the treatment device used in the process is smaller, the occupied area is less, the structure is compact, the management is easy, and compared with the traditional Fenton reaction, the process is more energy-saving and efficient;

(4) green and environment-friendly, when organic matter is oxidized, C is oxidized into CO₂N is oxidized to NH₃、NO^3-、N₂Organic and sulfide are oxidized into corresponding inorganic halides and sulfides without NO during the reaction_x、SO₂Harmful substances such as HCl and CO are generated, and no secondary pollution is caused;

(5) the process has low energy consumption and can recover reaction heat energy, the energy required for treating organic matters is the enthalpy difference between inlet water and outlet water, the reaction heat of the system can be used for heating the inlet water, the heat discharged from the system can be used for generating steam or heating water, and gas discharged by reaction is used for expanding a turbine to generate mechanical energy or electric energy and the like.

Drawings

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

FIG. 1 is a process flow diagram of an embodiment of the present invention.

In the figure, 1-buffer tank, 2-heat exchanger, 3-compressor, 4-ejector, 5-prereactor, 6-heater, 7-reactor, 8-cooler, 9-gas-liquid separator, 10-waste water source, 11-heat conducting oil furnace and 12-circulating pump.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A safe, energy-saving and efficient 'three-high' wastewater treatment process comprises the following steps:

(1) preheating waste water: introducing the wastewater to be treated into a cold chamber of a heat exchanger for preheating;

(2) waste water and air mixing and heating: the method comprises the steps of increasing air pressure by using a compressor, then spraying preheated wastewater and compressed air into a pre-reactor by using an injector for pre-reaction, and then mixing and heating by using a heater, wherein the theoretical required injection quantity A of the compressed air can be calculated according to a formula A which is 4.3COD (g air/L waste liquid), wherein COD represents the chemical oxygen demand for wastewater degradation, an air filter of the compressor adopts a program self-cleaning control mode, the pressure difference between two sides of the air filter is 150-650 Pa, the self-cleaning interval is 60s, the inlet temperature of the pre-reactor is controlled at 150-230 ℃, the pressure is controlled at 4.0-6.0, and when the pressure is low or high, the air volume of the compressed air can be properly increased or reduced;

(3) wet catalytic oxidation of wastewater: the method comprises the following steps of (1) enabling mixed heated wastewater and compressed air to enter a reactor for reaction, filling a ruthenium catalyst in the reactor, and controlling the temperature and pressure of an inlet, a bed layer and an outlet of the reactor, wherein specifically, the inlet temperature of the reactor is controlled to be 150-230 ℃, the pressure of the reactor is controlled to be 4.0-6.0 Mpa, the bed layer temperature is controlled to be 200-220 ℃, the pressure of the reactor is controlled to be 4.0-6.0 Mpa, the outlet temperature of the reactor is controlled to be 200-230 ℃, the pressure of the reactor is controlled to be 4.0-6.0 Mpa, the reaction time is controlled to be 0.1-2 hours, and the pH value of;

in the reaction process, the theoretical heat H released by the oxidation of the organic matters in unit mass is calculated according to the formula H of 4.3COD multiplied by 3.16 of 13.6COD (KJ/L waste liquid), wherein the COD is the chemical oxygen demand for wastewater degradation, and the part of heat can maintain the reaction temperature in the reactor, thereby achieving the purposes of saving energy and reducing consumption;

the temperature rise of the reactor can be adjusted by changing the compressed air quantity and the temperature of the inlet of the reactor, and when the adiabatic temperature rise of the wastewater passing through the bed layer is large and the pressure is high, the air quantity of the compressed air and the temperature of the inlet of the reactor can be properly reduced; when the adiabatic temperature rise of the wastewater passing through the bed layer is small and the pressure is low, the air quantity and the inlet temperature of the compressed air can be properly increased;

the gas discharged by the reaction can be used for expanding a turbine to generate mechanical energy or electric energy after being collected;

(4) a step of treating water separation: and (2) introducing the treated water into a heat cavity of the heat exchanger in the step (1), performing energy exchange with the wastewater to be treated as a heating medium, and then introducing the treated water into a gas-liquid separator to perform gas-liquid separation.

Example 2

On the basis of the embodiment 1, the air filter of the compressor can also adopt a differential pressure self-cleaning control mode, the differential pressure on two sides of the air filter is 650-1200 Pa, and the self-cleaning interval is 30 s.

Example 3

On the basis of embodiment 1 or embodiment 2, the following processing apparatus may be employed:

a three-high waste water treatment device comprises a buffer tank 1, a heat exchanger 2, a compressor 3 and an ejector 4, the system comprises a pre-reactor 5, a heater 6, a reactor 7, a cooler 8 and a gas-liquid separator 9, wherein a water inlet of a buffer tank 1 is connected with a waste water source 10 (such as a waste water storage tank, a waste water tank and the like), a water outlet of the buffer tank 1 is communicated with a cold flow inlet of a heat exchanger 2, a cold flow outlet of the heat exchanger 2 is communicated with a water inlet of an ejector 4, a compressor 3 is communicated with an air inlet of the ejector 4, a jet orifice of the ejector 4 is communicated with an inlet of the pre-reactor 5, an outlet of the pre-reactor 5 is communicated with an inlet of the heater 6, an outlet of the heater 6 is communicated with an inlet of the reactor 7, an outlet of the reactor 7 is communicated with a heat flow inlet of the heat exchanger 2, a heat flow outlet of the heat exchanger 2 is communicated with an inlet of the cooler 8, and an outlet of the cooler 8 is communicated with an inlet of the gas-liquid separator 9; the heat exchanger 2 can select different types according to suspended matters in the wastewater, when the suspended matters in the wastewater are more, a vertical countercurrent tube shell type heat exchanger is adopted, and when the suspended matters are less, a multi-tube type heat exchanger is adopted; the compressor 3 can be a three-section or four-section compound compressor, the heater 6 can be a heat conduction oil heater, a heat conduction oil outlet of the heater 6 is connected with a heat conduction oil furnace 11, and the heat conduction oil furnace 11 is communicated with a heat conduction oil inlet of the heater 6 through a circulating pump 12; the reactor 7 can be selected from a fixed bed dynamic reactor; the gas-liquid separator 9 may alternatively be a combined gas-liquid separator incorporating a cyclone assembly and baffles.

Example 4

The method of the embodiment 1 is used for treating the wastewater with three heights, the wastewater is preheated by a vertical countercurrent tube sleeve type heat exchanger, air is compressed by a three-section compound compressor and is injected into a pre-reactor through an injector, the temperature and the pressure in the pre-reactor are controlled, the mixed wastewater from the pre-reactor enters a fixed bed dynamic reactor after being heated by a heat conduction oil heater, a heterogeneous catalyst with ruthenium as a catalyst active component is filled in the reactor, the temperature and the pressure of an inlet, a bed layer and an outlet of the reactor are controlled, the reaction pH value is controlled, the wastewater reacts in the reactor for 1 hour, then treated water is obtained, the treated water enters the heat exchanger as a heating medium to exchange energy with the wastewater to be treated, the cooling is realized, and then the treated water enters a gas-liquid separator for separation.

The components before and after the wastewater treatment of the 'three high' wastewater are shown in the following tables 1 and 2, and it can be seen that the wastewater treatment process provided by the invention has a good removal effect on the 'three high' wastewater.

TABLE 1 composition before treatment of wastewater of "three highs

Serial number	Assay project	Index (I)	Analytical method
				1	Appearance of the product	Soy sauce black liquid	Visual inspection of
2	pH	9.5	Portable pH meter
				3	COD	2.06×105mg/l	Rapid digestion spectrophotometry (HJ/T399-2007)
4	TN	3.9×103mg/l	Ultraviolet spectrophotometry (GB/T11894-1989)
				5	TDS	9.39mg/l	Gravimetric method (GB/T11901-1989)
6	Toluenes	1.1×103mg/l	Chromatography method
				7	Cyanide compounds	0.0041mg/l
8	Total phenols	526mg/l	Chromatography method
				9	Carbonyl compounds such as formic acid	4.5×104mg/l
10	Organic chloride	1.52mg/l
				11	Ammonia nitrogen	1.3×103mg/l	Nashi reagent spectrophotometry (HJ535-2009)
12	Petroleum products	106mg/l	Chromatography method
				13	Suspended matter	124mg/l	Gravimetric method
14	Total phosphorus	102mg/l	Ammonium molybdate spectrophotometry (GB/T11903-1989)

TABLE 2 gas liquid separator liquid discharge composition

Although the present invention has been described in detail by referring to the drawings in connection with the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.