Process method for improving coagulation treatment efficiency through micro-nano air bag

Abstract

The invention discloses a process method for improving coagulation treatment efficiency through a micro-nano air bag, belongs to the field of water treatment processes, and particularly relates to an air bag coagulation liquid formed by adding a coagulant while preparing the micro-nano air bag in water. Adding the air bag coagulation liquid into the wastewater for coagulation treatment to obtain water subjected to coagulation treatment; the diameter of the micro-nano air bag is 200 nm to 50 [mu] m, and the molar ratio of the micro-nano air bag to the coagulant is controlled to be 1: (5-10). Three-phase mixing of the micro-nano air bag, the coagulant and the wastewater can be achieved, under the action of a hydraulic flow field, the coagulant and pollutants in the wastewater act to form a'water-gas-solid three-phase mixture ', under the synergistic effect of the micro-nano air bag, the three-phase mixture enters the air floatation tank after the reaction is rapidly finished, and the water-gas-solid three-phase mixture enters the air floatation tank. Most pollutants float to the water surface and are automatically removed through a slag scraper, and small parts of the pollutants precipitate to the bottom and are removed through a bottom suction dredger.

Description

Technical Field

[0001] The invention belongs to the field of water treatment technology, and specifically relates to a process method for improving coagulation treatment efficiency by using micro-nano airbags. Background Art

[0002] Although the coagulation and sedimentation method can play a very good purification role in wastewater treatment, its economic cost is relatively high in actual operation, and it requires a large amount of chemical agents and energy, and the impact on the environment cannot be ignored. At the same time, when treating wastewater, the coagulation and sedimentation method needs to constantly adjust the type and dosage of the agent to adapt to different water quality characteristics, which also increases the difficulty of its maintenance and management. Although the coagulation and sedimentation method can effectively remove suspended particles and organic matter in water, it is difficult to completely remove different types of pollutants in water. In addition, the hydraulic retention time of coagulation and sedimentation is relatively long, resulting in a large tank volume required for the mixing and sedimentation process of the coagulation and sedimentation tank, and high infrastructure and subsequent maintenance costs. In addition, during the treatment process of the coagulation and sedimentation method, a certain amount of sludge and wastewater will be generated. Sludge is a kind of solid waste that is difficult to treat and needs further treatment before it can be used for recycling or safe disposal. Wastewater needs to be further treated to meet the discharge standards. The generation and treatment of these wastes will increase the maintenance cost and management difficulty of the entire wastewater treatment system.

[0003] Traditional coagulation treatment relies on the effective contact and flocculation of coagulants and pollutants, but is often limited by the speed and density of floc formation, which affects the treatment efficiency and water purification effect. In general, although coagulation sedimentation is a widely used wastewater treatment technology, it also has some shortcomings that we need to recognize and improve. For the wastewater treatment industry, more efficient, energy-saving and environmentally friendly treatment technologies should be studied and explored to better protect the environment and human health. Summary of the invention

[0004] The object of the present invention is to provide a process method for improving the coagulation treatment efficiency by using micro-nano airbags, which can improve the coagulation effect, improve the SS removal rate in wastewater and improve the COD removal rate in wastewater.

[0005] The present invention proposes a process method for improving the efficiency of coagulation treatment by using micro-nano airbags, and utilizes the micro-nano airbags to carry charges and release processes to promote efficient mass transfer and reaction between the gas-liquid-solid three phases, thereby accelerating the coagulation process to overcome the above-mentioned technical problems existing in the existing related technologies. The purpose of the present invention is to address the problems of large dosage of reagents, long hydraulic retention time, large facility footprint, high operating cost, etc. in the coagulation and precipitation method of wastewater treatment, and adopt a process method with less dosage, more efficient reaction, and more economical and environmentally friendly.

[0006] The present invention provides a process method for improving the coagulation treatment efficiency by using micro-nano airbags. The process method comprises the following steps: while the micro-nano airbags are being formed, the coagulant is added and premixed to form an airbag coagulant liquid, and then the airbag coagulant liquid is added into the wastewater for mixing, so as to achieve three-phase mixing of the micro-nano airbags, the coagulant and the wastewater. By relying on the huge specific surface area of ​​the micro-nano airbags and utilizing the disturbance generated during the release process, the airbags react with the coagulant and pollutants such as suspended particulate matter in the wastewater under the action of a hydraulic flow field to form a "water-air-solid three-phase mixture". Under the synergistic action of the micro-nano airbags, the three-phase mixture reacts quickly and then enters an air flotation tank. Most of the pollutants float to the water surface and are automatically removed by a scraper, while a small part settles to the bottom and is removed by a bottom sludge suction machine.

[0007] The present invention discloses a method for improving the coagulation treatment efficiency by using micro-nano airbags, comprising: preparing micro-nano airbags in water and adding a coagulant to form an airbag coagulation liquid; adding the airbag coagulation liquid to wastewater for coagulation treatment to obtain coagulated water; the diameter of the micro-nano airbags is 200nm-50μm. The micro-nano airbags can be produced by a hydrodynamic cavitation method, which is a technology for producing micro-nano bubbles by hydraulic shearing. The method uses a high-speed flowing liquid to generate high pressure in a local area, and then suddenly reduces pressure in a low-pressure area, causing the gas dissolved in the liquid to be supersaturated and quickly released to form tiny bubbles.

[0008] The preparation of micro-nano airbags includes the following process: First, a liquid containing dissolved gas needs to be introduced into a channel or cavity designed with a special structure. This process can be achieved by a pump or a specific fluid power system. When the liquid passes through a narrow channel or an element of a specific geometry, it will experience acceleration and strong shear force, which increases the kinetic energy and turbulence inside the liquid. In certain parts of the flow channel, such as the expansion area after the stenosis, the pressure of the fluid will drop rapidly. This sudden change in pressure causes the gas dissolved in the liquid to reach a supersaturated state and quickly precipitate from the solution to form tiny gas nuclei. As the pressure is further reduced, these gas nuclei can rapidly expand into tiny bubbles, namely cavitation bubbles. In some cases, these cavitation bubbles may undergo periodic generation, growth, and interaction with the surrounding liquid, including possible violent collapse. This process can further refine the bubble size and generate smaller micro-nano bubbles.

[0009] Preferably, the micro-nano airbags are prepared by a hydrodynamic cavitation method; or, the coagulant includes an aluminum-based inorganic polymer coagulant, an iron-based inorganic polymer coagulant, or a composite polymer coagulant; or, the molar ratio of the micro-nano airbags to the coagulant is controlled to be 1:5-10. Coagulants include but are not limited to aluminum-based inorganic polymer coagulants, iron-based inorganic polymer coagulants, or composite polymer coagulants. Select or customize a high-efficiency coagulant suitable for synergistic action with the micro-nano airbags, such as an aluminum-based inorganic polymer coagulant or an iron-based inorganic polymer coagulant, and adjust its dosage to ensure the effective combination of the airbags and the coagulant.

[0010] Preferably, the aluminum-based inorganic polymer coagulant includes polyaluminum chloride, polyaluminum silicate, polyaluminum silicate sulfate or a mixture thereof; or, the iron-based inorganic polymer coagulant includes polyferric silicate, iron-aluminum composite flocculant or a mixture thereof.

[0011] Preferably, the diameter of the micro-nano airbag with the highest volume ratio in the micro-nano airbag is 40 μm; or, the molar ratio of the micro-nano airbag to the coagulant is controlled to be 1:5; or, the coagulant is polyaluminium chloride.

[0012] Preferably, the content of coagulant in the airbag coagulation liquid is 5-20wt%; or, the airbag coagulation liquid is added to the wastewater, and the amount of coagulant is 200-800ppm.

[0013] More preferably, the content of coagulant in the airbag coagulation liquid is 10wt%; or, the airbag coagulation liquid is added to the wastewater, and the amount of coagulant is 400ppm.

[0014] Preferably, the wastewater is coking wastewater, printing and dyeing wastewater, oily wastewater or a mixture thereof.

[0015] Preferably, in the coking wastewater, COD is 3000-4000 mg / L, and SS is 400-600 mg / L.

[0016] The invention discloses the preparation of airbag coagulation liquid. The hydrodynamic cavitation method is used to generate micro-nano airbags. When the micro-nano airbags are formed, the coagulant is added and premixed to form the airbag coagulation liquid.

[0017] Preferably, the coagulant is polyaluminium chloride, and the content of the coagulant in the airbag coagulation liquid is 5-20wt%.

[0018] Preferably, the diameter of the micro-nano airbags generated by the hydrodynamic cavitation method is 200nm-50μm, and the molar ratio of the micro-nano airbags to the coagulant is controlled to be 1:5-10. The diameter of the micro-nano airbags is characterized by the micro-nano airbags with the highest volume share, and the diameter distribution of the micro-nano airbags is relatively concentrated.

[0019] The present invention discloses a coagulation treatment of wastewater, wherein an airbag coagulation liquid is added to the coking wastewater, and after sufficient mixing, dense flocs are formed and settled under the action of gravity, and the water after coagulation treatment is obtained after separation treatment. After the airbag coagulation liquid is added to the coking wastewater, stirring treatment or static mixer treatment can be adopted to ensure that the micro-nano airbags and the coagulant are evenly dispersed and fully contact with the pollutants in the wastewater. The micro-nano airbags are slowly released in the wastewater, promoting the adhesion of bubbles and suspended particles, enhancing the flotation effect, and the active gas on the surface of the airbags accelerates the oxidation and decomposition process of the pollutants. The presence of the micro-nano airbags significantly increases the gas-liquid interface area, accelerates the adhesion of bubbles and colloidal particles and the formation of aggregates. After sufficient mixing, the dense flocs formed settle rapidly under the action of gravity, and the continuous action of the micro-nano airbags helps the floc structure to be more loose and porous, which is convenient for the discharge of water and improves the solid-liquid separation efficiency. After the airbag coagulant is added into the coking wastewater and fully mixed, the coagulant reacts with pollutants such as suspended particulate matter in the wastewater to form a "water-gas-solid three-phase mixture". During the separation treatment, under the synergistic effect of the micro-nano airbags, the three-phase mixture reacts quickly and then enters the flotation tank. Most of the pollutants float to the water surface and are automatically removed by the scraper, and a small part settles to the bottom and is removed by the bottom sludge suction machine.

[0020] Preferably, the amount of the airbag coagulation liquid used is measured based on the amount of coagulant therein so that the coagulant added to the coking wastewater is 200-800 ppm.

[0021] The invention discloses the use of a micro-nano airbag and a coagulant in wastewater treatment. The diameter of the micro-nano airbag is 200nm-50μm.

[0022] The present invention uses the method of superimposing and mixing micro-nano airbags and coagulants for use in wastewater treatment, which has the following beneficial effects: the agent (coagulant) and the dissolved air system (micro-nano airbags) can be customized according to the requirements of wastewater treatment, so that high-efficiency agents and high-efficiency premixing can be completed simultaneously; a "water-gas-solid three-phase mixture" is formed while adding the agent, which reduces or eliminates the coagulation tank and effectively reduces infrastructure investment and operation and maintenance costs; the "water-gas-solid three-phase mixture" gives full play to the superimposed effect of micro-nano airbags and coagulants, improves the adsorption effect of coagulants, and thus reduces the amount of coagulants used; the process method for improving the coagulation treatment efficiency by using micro-nano airbags has simple equipment and can be installed in an integrated manner in existing pipelines, reducing changes to existing processes, and has the advantages of simple process, easy use, and environmental protection.

[0023] Therefore, the present invention is a process method for improving the coagulation effect, improving the SS removal rate in wastewater and improving the COD removal rate in wastewater by using micro-nano airbags to improve the coagulation treatment efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1Diagram of the diameter of micro-nano airbags. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the context of the present invention, reaction may refer to a chemical reaction or a non-chemical bonding treatment method.

[0027] The following first describes the concepts involved in the present application in conjunction with the accompanying drawings. It should be noted that the following description of each concept is only to make the content of the present application easier to understand, and does not limit the scope of protection of the present application; at the same time, the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments.

[0028] Example 1: A process for improving coagulation efficiency by using micro-nano airbags Preparation of airbag coagulation liquid: Micro-nano airbags are generated by hydrodynamic cavitation. The coagulant is added and premixed at the same time as the micro-nano airbags are formed to form airbag coagulation liquid. The coagulant is polyaluminium chloride, and the content of the coagulant in the airbag coagulation liquid is 10wt%. The diameter of the micro-nano airbags generated by the hydrodynamic cavitation method is 40μm, and the molar ratio of the micro-nano airbags to the coagulant is controlled to be 1:5.

[0029] Coagulation treatment of wastewater: add the airbag coagulation liquid to the coking wastewater, mix it thoroughly, form dense flocs, settle under gravity, and separate to obtain coagulated water. The amount of airbag coagulation liquid used is measured according to the amount of coagulant in it, so that the coagulant added to the coking wastewater is 400ppm. After the airbag coagulation liquid is added to the coking wastewater, stirring treatment is adopted to ensure that the micro-nano airbags and coagulants are evenly dispersed and fully contact with the pollutants in the wastewater. After the airbag coagulation liquid is added to the coking wastewater and mixed thoroughly, the coagulant reacts with pollutants such as suspended particles in the wastewater to form a "water-gas-solid three-phase mixture". During the separation treatment, under the synergistic effect of the micro-nano airbags, the three-phase mixture reacts quickly and then enters the flotation tank. Most of the pollutants float to the water surface and are automatically removed by the scraper, and a small part settles to the bottom and is removed by the bottom sludge suction machine.

[0030] The diameter of the micro-nano airbags used in the method of Example 1 was tested by the present invention. The diameter of the micro-nano airbags was analyzed using a MS3000 laser particle size analyzer (Malvern Instruments, UK). The results are as follows: Figure 1 As shown, the particle size of 40 μm accounts for the largest proportion by volume, and its distribution is relatively concentrated, indicating that the bubbles generated by the microbubble aeration equipment used in this experiment are uniform.

[0031] On the basis of Example 1, the present invention designs a method of using only PAC flocculation and sedimentation, the amount of PAC used is 400ppm, and the airbag coagulation liquid is replaced with the coagulation liquid without micro-nano airbags in the coagulation treatment of wastewater, and the results are shown in Table 1. The method of Example 1 adopted in Table 1 is consistent with the conditions of Example 1 unless otherwise specified.

[0032] Table 1 Comparison of micro-nano airbag-assisted PAC flocculation and sedimentation effects Flocculation sedimentation method Settling time (min) SS removal rate (%) COD removal rate (%) PAC 400ppm 10 65 73 PAC 400ppm 25 78 82 Micro-nano airbag assisted PAC 400ppm 10 98 95 Micro-nano airbag assisted PAC 400ppm 25 99 97 Micro-nano airbag 10 No removal effect No removal effect Micro-nano airbag 25 No removal effect No removal effect Natural Settlement 10 No removal effect No removal effect Natural Settlement 25 No removal effect No removal effect The present invention found that coking wastewater is quite stable and natural sedimentation requires a hydraulic retention time of several hours or even several days to see the effect. In industrial wastewater treatment, due to the limitation of tank capacity, natural sedimentation is basically not used. Therefore, in a short period of time, natural sedimentation can be considered to have no removal effect.

[0033] The present invention found that when only PAC is used to flocculate coking wastewater, the SS removal rate and COD removal rate will not increase with the increase in dosage. Excessive addition will have the opposite effect. The 400 used in the present invention is basically the best removal effect of PAC.

[0034] In the process of micro-nano airbag assisted coagulation, the removal rates of SS and COD in water can reach 98% and 95%, while the removal rates of SS and COD in the process without the assistance of micro-nano bubbles and only adding 400ppm PAC are only 78% and 82%, and the sedimentation time is also shortened from 25min to 10min. This process embodiment significantly improves the removal efficiency of pollutants in the coagulation process, shortens the processing time, and reduces the amount of coagulant used, which has higher environmental friendliness and economy. In addition, the active gas carried by the airbag also promotes the oxidative decomposition of some difficult-to-degrade organic matter, broadening the application scope of coagulation technology.

[0035] Example 2: A process for improving coagulation efficiency by using micro-nano airbags Compared with Example 1, this example is different in the preparation of the airbag coagulation liquid.

[0036] Preparation of airbag coagulation liquid: Micro-nano airbags are generated by hydrodynamic cavitation. The coagulant is added and premixed at the same time as the micro-nano airbags are formed to form airbag coagulation liquid. The coagulant is polyaluminium chloride, and the content of the coagulant in the airbag coagulation liquid is 8wt%. The diameter of the micro-nano airbags generated by the hydrodynamic cavitation method is 40μm, and the molar ratio of the micro-nano airbags to the coagulant is controlled to be 1:8.

[0037] Example 3: A process for improving coagulation treatment efficiency by using micro-nano airbags Compared with Example 1, this example is different in the preparation of the airbag coagulation liquid.

[0038] Preparation of airbag coagulation liquid: Micro-nano airbags are generated by hydrodynamic cavitation. The coagulant is added and premixed at the same time as the micro-nano airbags are formed to form airbag coagulation liquid. The coagulant is polyaluminium chloride, and the content of the coagulant in the airbag coagulation liquid is 15wt%. The diameter of the micro-nano airbags generated by the hydrodynamic cavitation method is 40μm, and the molar ratio of the micro-nano airbags to the coagulant is controlled to be 1:10.

[0039] Example 4: A process for improving coagulation treatment efficiency by using micro-nano airbags Compared with Example 1, this example is different in the preparation of the airbag coagulation liquid.

[0040] Preparation of airbag coagulation liquid: Micro-nano airbags are generated by hydrodynamic cavitation. The coagulant is added and premixed at the same time as the micro-nano airbags are formed to form airbag coagulation liquid. The coagulant is polyaluminium chloride, and the content of the coagulant in the airbag coagulation liquid is 10wt%. The diameter of the micro-nano airbags generated by the hydrodynamic cavitation method is 20μm, and the molar ratio of the micro-nano airbags to the coagulant is controlled to be 1:8.

[0041] Example 5: A process for improving coagulation treatment efficiency by using micro-nano airbags Compared with Example 1, this example is different in the preparation of the airbag coagulation liquid.

[0042] Preparation of airbag coagulation liquid: Micro-nano airbags are generated by hydrodynamic cavitation. The coagulant is added and premixed at the same time as the micro-nano airbags are formed to form airbag coagulation liquid. The coagulant is polyaluminium chloride, and the content of the coagulant in the airbag coagulation liquid is 10wt%. The diameter of the micro-nano airbags generated by the hydrodynamic cavitation method is 10μm, and the molar ratio of the micro-nano airbags to the coagulant is controlled to be 1:10.

[0043] The methods of Examples 2-5 of the present invention all have excellent treatment effects on coking wastewater.

[0044] The embodiments and / or implementation methods described above are only used to illustrate the preferred embodiments and / or implementation methods for realizing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any form. Any technical personnel in this field may make slight changes or modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as technologies or embodiments that are essentially the same as the present invention.

[0045] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the invention to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A method for improving the efficiency of coagulation treatment by using micro-nano airbags, comprising: When preparing micro-nano airbags in water, a coagulant is added to form an airbag coagulation liquid; the airbag coagulation liquid is added to wastewater for coagulation treatment to obtain coagulated water; The diameter of the micro-nano airbag is 200nm-50μm.

2. The method for improving the coagulation treatment efficiency by using micro-nano airbags according to claim 1, characterized in that: The micro-nano airbags are prepared by a hydrodynamic cavitation method; or, the coagulant includes an aluminum-based inorganic polymer coagulant, an iron-based inorganic polymer coagulant or a composite polymer coagulant; or, the molar ratio of the micro-nano airbags to the coagulant is controlled to be 1:5-10.

3. The method for improving the coagulation treatment efficiency by using micro-nano airbags according to claim 2, characterized in that: The aluminum-based inorganic polymer coagulant includes polyaluminum chloride, polyaluminum silicate, polyaluminum silicate sulfate or a mixture thereof; or, the iron-based inorganic polymer coagulant includes polyferric silicate, iron-aluminum composite flocculant or a mixture thereof.

4. A method for improving coagulation treatment efficiency by using micro-nano airbags according to claim 1 or 2, characterized in that: The diameter of the micro-nano airbag with the highest volume ratio in the micro-nano airbag is 40 μm; or, the molar ratio of the micro-nano airbag to the coagulant is controlled to be 1:5; or, the coagulant is polyaluminium chloride.

5. The method for improving the coagulation treatment efficiency by using micro-nano airbags according to claim 1, characterized in that: The content of coagulant in the airbag coagulation liquid is 5-20wt%; or, the airbag coagulation liquid is added into wastewater, and the amount of coagulant is 200-800ppm.

6. The method for improving the coagulation treatment efficiency by using micro-nano airbags according to claim 5, characterized in that: The content of coagulant in the airbag coagulation liquid is 10wt%; or, the airbag coagulation liquid is added into wastewater, and the amount of coagulant is 400ppm.

7. The method for improving the coagulation treatment efficiency by using micro-nano airbags according to claim 1, characterized in that: The wastewater is coking wastewater, printing and dyeing wastewater, oily wastewater or a mixture thereof.

8. The method for improving the coagulation treatment efficiency by using micro-nano airbags according to claim 7, characterized in that: The COD in the coking wastewater is 3000-4000 mg / L.

9. The method for improving the coagulation treatment efficiency by using micro-nano airbags according to claim 7, characterized in that: In the coking wastewater, SS is 400-600 mg / L.

10. Use of micro-nano airbags and coagulants in wastewater treatment, wherein the diameter of the micro-nano airbags is 200nm-50μm.

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