CN113683236A

CN113683236A - Advanced oxidation reaction process using water as medium

Info

Publication number: CN113683236A
Application number: CN202110799567.XA
Authority: CN
Inventors: 刘忻; 吴建华; 刘锋; 高仕谦; 王俊霞; 李勇; 马三剑
Original assignee: Foshan Nanhai Suke Environmental Research Institute; Suzhou University of Science and Technology
Current assignee: Foshan Nanhai Suke Environmental Research Institute; Suzhou University of Science and Technology
Priority date: 2021-07-15
Filing date: 2021-07-15
Publication date: 2021-11-23
Anticipated expiration: 2041-07-15
Also published as: CN113683236B

Abstract

An advanced oxidation process with water as a medium, comprising: the wastewater enters a pretreatment device, suspended particles are removed by oxygen, odor, chromaticity, germs and organic matters are partially removed, and the water body is reoxygenated; then the effluent enters an advanced reduction device, odor, chromaticity, germs and organic matters are removed again through hydrogen, and the organic matters which are easy to reduce and difficult to oxidize are reduced into intermediate products through active hydrogen; then the effluent enters an advanced oxidation device, and organic matters in the water are mineralized by ROS generated by the reaction of hydrogen peroxide and Fe (II); then the effluent enters a sedimentation tank for mud-water separation, and then the effluent reaches the standard; the precipitated sludge is sent into a concentration tank, the iron sludge in the concentration tank enters an activation tank, and is activated into Fe (II) by hydrogen and a catalyst and then reflows to an advanced oxidation device again. The invention takes the water in the wastewater as a medium for self purification treatment, and has the advantages of high efficiency, environmental friendliness, no secondary pollution and the like when the organic matter polluted water body is repaired.

Description

Advanced oxidation reaction process using water as medium

Technical Field

The invention relates to the technical field of water pollution control, in particular to an advanced oxidation reaction process taking water as a medium.

Background

In the last four decades, with the rapid development of the industry in China, a large amount of industrial organic wastewater and waste are discharged into water in disorder, the self-purification capacity of the water body is exceeded, and the water environment is seriously polluted. Because organic pollution components in industrial wastewater are complex and have certain biological toxicity, the organic pollution components cannot be effectively removed by a conventional water treatment process. If people and livestock drink polluted water, pollutants can be taken into the body through drinking water, can significantly affect the endocrine system, are accumulated in the body, are difficult to metabolize rapidly, and can cause canceration, distortion and gene mutation of organisms for a long time. With the increasing importance of people on their health, a water treatment process capable of efficiently removing organic pollution is urgently needed to ensure the safety of water body environment.

A physicochemical treatment mode represented by advanced Oxidation AOPs (advanced Oxidation processes) technology is a new water treatment technology which has emerged for nearly 20 years, and the essence of the technology is to generate active species (such as hydroxyl radical. OH and singlet oxygen) through artificial enhancement¹O₂Sulfate radical SO₄ ^-·Reactive Oxygen Species (ROS) represented by a percarbonate radical, or atomic hydrogen) and the degradation thereof to remove organic substances in water, so that the active Oxygen Species are rapidly mineralized and degraded into CO₂And water, or is efficiently reduced to biodegradable matter.

The physicochemical treatment mode has the characteristic of fast process reaction and is theoretically suitable for treating all organic wastewater, but no matter which active species is taken as the main species, the physicochemical treatment mode can only singly oxidize or reduce specific pollutants and cannot treat the pollutants at the same time; meanwhile, in order to produce active species to degrade pollutants, a large amount of chemical agents are usually added, only part of components in the chemical agents usually play a role, the rest components do not play a role, and finally the chemical agents enter a water body and can further react with other substances in the water to generate potential/actual new pollutants so as to cause secondary pollution. For example, a large amount of ferrous salt and hydrogen peroxide are required to be added in the Fenton reaction (Fenton reaction) to maintain the generation of OH, and a large amount of iron mud is generated when the pH is adjusted to 6-9 after the reaction is finished to meet the discharge requirement; with SO₄ ^-·In the advanced oxidation reaction which is mainly carried out, persulfate needs to be continuously added to meet the requirement of SO₄ ^-·Is continuously generated, after the reaction is finished, SO in the effluent is generated₄ ^2-The content is extremely high. The reason for this is that the above treatment methods all regard water and pollutants as two independent individuals, and water can only be purified passively by removing pollutants, and cannot participate in the purification treatment itself.

Therefore, how to solve the above-mentioned deficiencies of the prior art is a problem to be solved by the present invention.

Disclosure of Invention

The invention aims to provide a water-mediated advanced oxidation reaction process.

In order to achieve the purpose, the invention adopts the technical scheme that:

a water-mediated advanced oxidation process, comprising:

step one, carrying out pretreatment of wastewater

The method comprises the following steps that the wastewater is filtered and adjusted to have pH of 6-9, then the wastewater enters a pretreatment device, effluent of the pretreatment device enters a gas generation device, hydrogen and oxygen are generated through electrolysis, the oxygen is sent back to the pretreatment device in a micro-nano bubble mode, suspended particles in the wastewater are removed through the oxygen, meanwhile, odor, chromaticity, germs and organic matters are partially removed, and water is reoxygenated;

step two, carrying out advanced reduction reaction of the wastewater

The effluent after pretreatment is adjusted to pH value less than or equal to 7 and then enters an advanced reduction device, meanwhile, a gas generation device sends hydrogen into the advanced reduction device in the form of micro-nano bubbles, odor, chromaticity, germs and organic matters in water in the advanced reduction device are further removed by the hydrogen, and the hydrogen is activated into active hydrogen by a catalyst and then the organic matters which are easy to reduce and difficult to oxidize in the water are reduced into low-toxicity or nontoxic intermediate products;

step three, carrying out advanced oxidation reaction of wastewater

Adjusting the pH of the effluent after the advanced reduction reaction to be less than or equal to 5, then feeding the effluent into an advanced oxidation device, simultaneously feeding hydrogen peroxide and Fe (II) into the advanced oxidation device, and mineralizing organic matters in the water by ROS generated by the reaction of the hydrogen peroxide and the Fe (II);

step four, precipitating the effluent

Adjusting the pH of the effluent after the advanced oxidation reaction to 6-9, then, allowing the effluent to enter a sedimentation tank for mud-water separation, and then, discharging the effluent after reaching the standard;

part of the effluent is returned to the gas generating device through a pipeline and is used as a raw material for generating hydrogen and oxygen;

the sludge precipitated in the sedimentation tank comprises iron sludge, the sludge is sent into a concentration tank, the supernatant in the concentration tank flows back to a pretreatment device for continuous treatment, and the iron sludge in the concentration tank enters an activation tank; in the activation pool, the iron mud is added with acid to adjust the pH value to be less than or equal to 3.5, then is activated into Fe (II) by hydrogen and the catalyst, and then flows back to the high-grade oxidation device again.

The relevant content in the above technical solution is explained as follows:

1. in the scheme, in the step one, after the wastewater is filtered by a grating or a wool fishing machine, the pH value is adjusted to 6-9, and then the wastewater enters a pretreatment device;

when wastewater is pretreated in a pretreatment apparatus, a coagulant is added.

2. In the scheme, hydrogen peroxide is generated by a hydrogen peroxide generating device and is sent to a high-grade oxidation device;

hydrogen and oxygen generated by the gas generating device are sent into the hydrogen peroxide generating device, and the hydrogen peroxide generating device generates hydrogen peroxide through reaction;

and after the advanced oxidation reaction, redundant hydrogen and oxygen return to the hydrogen peroxide generation device to continuously react to generate hydrogen peroxide.

3. In the scheme, a water outlet of the advanced oxidation device is communicated with a sedimentation tank, a sludge outlet of the sedimentation tank is communicated with a concentration tank, and sludge of the concentration tank is communicated with an activation tank;

the water inlet of the gas generating device is communicated with the pretreatment device or/and the effluent of the sedimentation tank; the hydrogen output port of the gas generating device is also communicated with the activation tank, the hydrogen is introduced into the activation tank and activated into active hydrogen through a catalyst, Fe (III) in the sludge discharged from the concentration tank is reduced into Fe (II), and then the Fe (II) is sent into the advanced oxidation device to participate in the reaction.

4. In the above scheme, the oxygen output port and the hydrogen output port of the gas generating device are respectively connected with a bubble generating device, the bubble generating device comprises an aeration pipe, and a plurality of air holes are formed in the aeration pipe.

The working principle and the advantages of the invention are as follows:

the invention utilizes water in the wastewater to spontaneously generate hydrogen and oxygen:

1. part of oxygen enters the water of the pretreatment device in the form of micro-nano bubbles, can degrade and remove suspended particles in the inlet water, and part of odor, chroma, germs and organic matters, and oxygenate the water body; introducing the rest oxygen into a hydrogen peroxide generation device, reacting with hydrogen to generate hydrogen peroxide, and then sending the hydrogen peroxide into an advanced oxidation device for Fenton reaction;

2. a part of hydrogen is released into water of an advanced reduction device in a micro-nano bubble form, part of odor, chromaticity and germs in the inlet water can be degraded and removed, and organic matters which are easy to reduce and difficult to oxidize in the water are reduced into low-toxicity or non-toxic intermediate products after being activated into active hydrogen through a catalyst; introducing the other part of hydrogen into a hydrogen peroxide generation device, reacting with oxygen to generate hydrogen peroxide, and then sending the hydrogen peroxide into an advanced oxidation device for Fenton reaction; the rest hydrogen is introduced into an activation tank and activated into active hydrogen by a catalyst, which is used for accelerating the reduction of Fe (III) in the system into Fe (II), and Fe (II) can be sent into an advanced oxidation device to participate in the reaction.

Compared with the prior art, the invention considers the pollutants and water in the wastewater as a unified whole, takes the water in the wastewater as a medium, and spontaneously generates active substances for purifying the pollutants in the wastewater through manual regulation, thereby achieving the purpose of reducing secondary pollution; after the purification is finished, redundant active substances can be artificially regulated to generate water again.

The invention removes floating materials and particles in water through pretreatment, adjusts pH, and then leads water and dissolved oxygen in the wastewater to be spontaneously decomposed to generate oxidative ROS (hydrogen peroxide, ozone, OH and singlet oxygen) through external input light, electricity, sound, heat or radiation or specific catalyst¹O₂) And reducing atomic hydrogen and hydrogen gas, which directly react with the pollutants in the water to degrade and remove the pollutants.

The invention solves the problems of physicochemical treatment, particularly large-scale storage and addition of reaction reagents in advanced oxidation reaction, all the reaction reagents are prepared on site in real time, and the problem of generating a large amount of iron mud in the application of a Fenton method is also solved. The method is used for repairing the organic substance polluted water body and has the advantages of high efficiency, environmental friendliness, no secondary pollution and the like.

The advantages of the invention include:

1. the reaction can be carried out at normal temperature and normal pressure, complex operation is not needed, the process is compact and easy to operate, the design of a water treatment unit module is simple, and reaction modules can be flexibly increased and decreased according to needs;

2. only acid and alkali agents are added to adjust the pH value, so that the periodic self-supplement of Fe (II) can be realized, the mineralization and degradation of organic matters are fast and thorough, the application range is wide, and the catalyst can be repeatedly used for a long time;

3. the method is environment-friendly and does not cause secondary pollution;

4. the utilization rate of the iron mud is improved, and the disposal cost of the iron mud is reduced.

Drawings

FIG. 1 is a block diagram of a water treatment process according to an embodiment of the present invention;

FIG. 2 is a block diagram of a preprocessing unit according to an embodiment of the present invention;

FIG. 3 is a structural and functional block diagram of a reaction unit according to an embodiment of the present invention.

In the above drawings: 1. a pretreatment device; 2. a gas generating device; 3. a grating or a wool scooping machine; 4. an advanced reduction device; 5. an advanced oxidation unit; 6. a hydrogen peroxide generating device; 7. a sedimentation tank; 8. an activation tank; 9. and (5) a concentration tank.

Detailed Description

The invention is further described with reference to the following figures and examples:

example (b): the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the disclosure may be shown and described, and which, when modified and varied by the techniques taught herein, can be made by those skilled in the art without departing from the spirit and scope of the disclosure.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms "a", "an", "the" and "the", as used herein, also include the plural forms.

The terms "first," "second," and the like, as used herein, do not denote any order or importance, nor do they denote any order or importance, but rather are used to distinguish one element from another element or operation described in such technical terms.

As used herein, the terms "comprising," "including," "having," and the like are open-ended terms that mean including, but not limited to.

As used herein, the term (terms), unless otherwise indicated, shall generally have the ordinary meaning as commonly understood by one of ordinary skill in the art, in this written description and in the claims. Certain words used to describe the disclosure are discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the disclosure.

The invention relates to a water-mediated advanced oxidation reaction process method, which is realized by a reaction device, wherein the reaction device comprises a pretreatment unit and a reaction unit.

As shown in fig. 2, the pretreatment unit includes a pretreatment device 1 and a gas generation device 2.

The pretreatment device 1 is provided with a wastewater inlet, and wastewater is subjected to grating or fur fishing machine 3 to remove large floating objects and garbage and then flows into the pretreatment device 1 through the wastewater inlet; the gas generating device 2 is used for generating hydrogen and oxygen and is provided with an oxygen output port and a hydrogen output port, and the oxygen output port is communicated with an oxygen inlet of the pretreatment device 1.

As shown in fig. 3, the reaction unit includes a high-level reduction device 4, a high-level oxidation device 5, a hydrogen peroxide generation device 6, a sedimentation tank 7, an activation tank 8, and a concentration tank 9.

The water inlet of the advanced reduction device 4 is communicated with a water outlet of the pretreatment device 1 to receive pretreated outlet water. The hydrogen outlet of the gas generating device 2 is communicated with the gas inlet of the advanced reduction device 4, and the water outlet of the advanced reduction device 4 is communicated with the first water inlet of the advanced oxidation device 5.

The water outlet of the advanced oxidation device 5 is communicated with a water inlet of the sedimentation tank 7; the sedimentation tank 7 also comprises a sedimentation area and a water outlet positioned at the upper part of the sedimentation area. The effluent from the sedimentation tank 7 is the purified water after water treatment, and part of the purified water can be returned to the gas generator 2 for the latter to generate hydrogen and oxygen.

The gas generating device 2 is provided with a water inlet which is communicated with a water outlet of the pretreatment device 1 or/and a water outlet of the sedimentation tank 7; the hydrogen output port of the gas generating device 2 is also communicated with a hydrogen inlet of the hydrogen peroxide generating device 6 and a gas inlet of the activation tank 8; the pipeline for outputting hydrogen can be three or one-to-three. The oxygen output port of the gas generating device 2 is also communicated with the oxygen inlet of the hydrogen peroxide generating device 6, and the pipeline for outputting oxygen can be two pipelines or one pipeline and two pipelines.

And the water outlet of the hydrogen peroxide generation device 6 is communicated with the second water inlet of the advanced oxidation device 5.

And a sludge outlet of the sedimentation tank 7 is communicated with a sludge inlet of the concentration tank 9, and supernatant overflowing from the concentration tank 9 flows back to the pretreatment device 1 of the pretreatment unit.

And a sludge outlet of the concentration tank 9 is communicated with the activation tank 8, and the activation tank 8 is communicated with the advanced oxidation reaction device 5 through a pipeline.

As shown in fig. 1, the reaction process of the present invention comprises:

step one, pretreatment

The method comprises the following steps that the wastewater enters a pretreatment device 1 after the pH value of the wastewater is adjusted to be 6-9, meanwhile, oxygen is sent into the pretreatment device 1 in a micro-nano bubble mode through a gas generation device 2, suspended particles in the wastewater are removed through the oxygen, meanwhile, odor, chromaticity, germs and organic matters are partially removed, and the water body is reoxygenated;

the micro-nano bubble effect of the oxygen comprises the following steps: 1) the micro-nano bubble has large specific surface area, is beneficial to gas-liquid mass transfer and is beneficial to reoxygenation of a water body; 2) the micro-nano bubbles can change the state of a gas-liquid interface between the micro-nano bubbles and water, are beneficial to the generation of ROS particles, and are more used for oxidizing and degrading organic pollutants.

Step two, advanced reduction reaction

And (3) adjusting the pretreated effluent to pH less than or equal to 7, then feeding the effluent into the advanced reduction device 4, simultaneously feeding hydrogen into the advanced reduction device 4 in the form of micro-nano bubbles by the gas generation device 2, and removing odor, chromaticity, germs and organic matters in the water body again through the micro-nano bubbles of the hydrogen. And after activating hydrogen into active hydrogen by a catalyst, the water is easy to reduce and difficult to oxidizeReducing the organic material to a less toxic or non-toxic intermediate, such as dehalogenating the halogenated groups attached to the benzene ring (e.g., converting pentachlorobenzene to tetrachlorobenzene, trichlorobenzene, dichlorobenzene, and the like; halogenated phenolic contaminants may also be dehalogenated in this manner); such as the conversion of nitro groups to amino groups; such as decolorization of the dye by opening the azo bond in the azo dye; such as defluorination of perfluorooctanoic acid-like organic compounds. The catalyst may be Ni⁰/Pd⁰Or Pt⁰Or micro-mesoporous materials such as MOFs or COFs materials, and the like, and the catalyst used as an effective active component can be specifically a supported form such as Pd/MOFs or Pd @ MOFs.

The excess hydrogen is returned to the high-level reduction device 4 to continue the reaction.

Step three, advanced oxidation reaction

The effluent after the advanced reduction reaction is adjusted to pH less than or equal to 5 and then enters an advanced oxidation device 5, meanwhile, hydrogen peroxide generated by the hydrogen peroxide generating device 6 is sent to the advanced oxidation device 5, and activated and regenerated Fe (II) is sent to the advanced oxidation device 5 by an activation tank 8. In the advanced oxidation device 5, organic matters in water are mineralized by ROS (reactive oxygen) generated by the reaction of hydrogen peroxide and Fe (II), and redundant hydrogen and oxygen flow back to the hydrogen peroxide generation device 6 to continue to react to generate hydrogen peroxide;

specifically, hydrogen and oxygen can generate hydrogen peroxide under the action of a palladium-containing catalyst. Or may be produced by electrolysis. The specific hydrogen peroxide generation mechanism is the prior art, and therefore, the scheme is not described in detail.

Step four, precipitating the effluent

Adjusting the pH of the effluent after the advanced oxidation reaction to 6-9, then, allowing the effluent to enter a sedimentation tank 7 for mud-water separation, and then, discharging the effluent after reaching the standard; part of the effluent is returned to the gas generating device 2 through a pipeline to be used as a raw material for generating hydrogen and oxygen;

the sludge precipitated in the sedimentation tank 7 comprises iron sludge, the sludge is sent into a concentration tank 9, the supernatant of the concentration tank 9 flows back to the pretreatment device 1 for continuous treatment, and the iron sludge in the concentration tank 9 enters an activation tank 8; in the activation tank 8, the iron mud is activated into Fe (II) by hydrogen and the catalyst after being adjusted to pH less than or equal to 3.5 by adding acid, and then reflows to the advanced oxidation device 5 again for supplementing the loss of Fe (II) in the system caused by the outlet water.

In the first step, after being filtered by a grating or a wool fishing machine, the wastewater is adjusted to have a pH value of 6-9 and then enters a pretreatment device; when the wastewater is pretreated in the pretreatment device, coagulant can be added to ensure that the concentration of suspended solids SS in the pretreated effluent is not more than 200 mg/L.

Preferably, the oxygen output port and the hydrogen output port of the gas generating device 2 are respectively connected with a bubble generating device, and the bubble generating device comprises an aeration pipe, and the aeration pipe is provided with a plurality of air holes. Taking oxygen as an example, before oxygen enters the pretreatment device 1, micro-nano bubbles can be generated by the bubble generation device, so that the oxygen can be mixed with the wastewater more fully. Oxygen and hydrogen form bubbles through a plurality of air holes on the aeration pipe, and the bubbles can be cut into micro-nano bubbles with smaller diameter through high-speed rotation.

The pretreatment device 1 is also provided with an oxygen outlet which is communicated with the hydrogen peroxide generation device 6 so as to convey redundant oxygen to the hydrogen peroxide generation device 6 for utilization.

The advanced reduction device 4 comprises a hydrogen return pipeline, one end of the hydrogen return pipeline is connected above the advanced reduction device 4, and the other end of the hydrogen return pipeline is communicated with a gas inlet of the advanced reduction device 4 and is used for returning redundant hydrogen to the advanced reduction device for recycling.

The advanced oxidation device 5 comprises an oxygen pipeline and a hydrogen pipeline, and the two pipelines are both communicated with the hydrogen peroxide generation device 6 and used for returning the generated hydrogen and oxygen to the hydrogen peroxide generation device 6 for use.

In conclusion, the invention removes floating substances and particles in water through pretreatment, adjusts the pH value, and then leads water and dissolved oxygen in the wastewater to be spontaneously decomposed to generate oxidative ROS (hydrogen peroxide, ozone, OH and singlet oxygen) through electrochemical reaction or external input light, sound, heat, radiation or specific catalyst¹O₂) And reducing atomic hydrogen and hydrogen gas, directly reacting with sewage in waterAnd (4) carrying out a dye reaction to degrade and remove the pollutants.

The special catalyst mainly selects FeII which is used for activating hydrogen peroxide to generate ROS.

The treatment effect of the present invention is illustrated by three sets of experimental data as follows:

experiment 1: treatment of printing and dyeing wastewater

Aiming at the restoration of the polluted water source of the printing and dyeing wastewater, COD is used_CrThe printing and dyeing wastewater with the concentration of 281.02 mg/L is taken as target wastewater, electrolysis is taken as a hydrogen and oxygen source, and the reaction time is 2 h. COD_CrThe removal rate is shown in table 1.

TABLE 1

Sampling time (h)	COD_CrRemoval rate
		0	0
0.5	40.86%
		1	66.32%
1.5	81.82%
		2	96.70%

Experiment 2: treating pesticide waste water

By COD_CrThe pesticide wastewater with the concentration of 221.62 mg/L is taken as target wastewater, irradiation is taken as a hydrogen and oxygen source, and the reaction time is 2 h. COD_CrThe removal rate is shown in table 2.

TABLE 2

Sampling time (h)	COD_CrRemoval rate
		0	0
0.5	46.36%
		1	61.52%
1.5	83.68%
		2	98.72%

Experiment 3: treatment of chemical industrial park wastewater

By COD_CrThe chemical industrial park wastewater with the concentration of 308.42 mg/L is taken as target wastewater, the illumination is taken as a hydrogen and oxygen source, and the reaction time is 2 h. COD_CrThe removal rate is shown in Table 3.

TABLE 3

Sampling time (h)	COD_CrRemoval rate
		0	0
0.5	41.42%
		1	58.96%
1.5	75.88%
		2	98.64 %

The invention solves the problems of physicochemical treatment, particularly large-scale storage and addition of reaction reagents in advanced oxidation reaction, all the reaction reagents are prepared on site in real time, and the problem of generating a large amount of iron mud in the application of a Fenton method is also solved. The method is used for repairing the organic substance polluted water body and has the advantages of high efficiency, no selectivity, environmental friendliness, no secondary pollution and the like.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A water-mediated advanced oxidation reaction process is characterized in that: the method comprises the following steps:

step one, carrying out pretreatment of wastewater

step two, carrying out advanced reduction reaction of the wastewater

step three, carrying out advanced oxidation reaction of wastewater

step four, precipitating the effluent

2. The process according to claim 1, characterized in that: in the first step, after being filtered by a grating or a wool fishing machine, the wastewater is adjusted to have a pH value of 6-9 and then enters a pretreatment device;

3. The process according to claim 1, characterized in that: hydrogen peroxide is generated by a hydrogen peroxide generating device and is sent into a high-grade oxidation device;

4. The process according to claim 1, characterized in that: the water outlet of the advanced oxidation device is communicated with a sedimentation tank, a sludge outlet of the sedimentation tank is communicated with a concentration tank, and the sludge outlet of the concentration tank is communicated with an activation tank;

5. The process according to claim 1, characterized in that: the oxygen output port and the hydrogen output port of the gas generating device are respectively connected with a bubble generating device, and the bubble generating device comprises an aeration pipe, and a plurality of air holes are formed in the aeration pipe.