CN116891291A - Multi-layer structure mixed nutrition type limit denitrification carrier and preparation and application thereof - Google Patents

Abstract

The invention discloses a multilayer structure mixed nutrition type limit denitrification carrier and preparation and application thereof, wherein the multilayer structure mixed nutrition type limit denitrification carrier is a core-shell structure, an inorganic core comprises an autotrophic functional material and a buffer material, and a multilayer organic shell structure is compounded to the outer layer of the inorganic core in an alternate loading mode of heterotrophic functional materials and structural components, so that the controllability of the release process of the functional materials and the service life of the carrier are enhanced; the multi-layer structure mixed nutrition type limit denitrification carrier is an autotrophic-heterotrophic composite denitrification system, mainly aims at the deep denitrification requirements of sewage with low nitrogen pollution and low carbon nitrogen ratio such as tail water and surface water of a sewage plant, can be used for a typical water quality purification system represented by a biological fluidized bed, a biological filter and an artificial wetland, can reach the surface water environment quality standard (GB 3838-2002) class III water standard without adding an organic carbon source medicament, and has the advantages of low cost, simplicity in preparation, wide application range, good hydraulic performance and the like.

Description

A multi-layer structure mixotrophic extreme denitrification carrier and its preparation and application

Technical field

The invention relates to the technical field of water depth treatment, and more specifically to a multi-layer structure mixotrophic extreme denitrification carrier and its preparation and application.

Background technique

As the quality of the water ecological environment has received more and more attention, higher requirements have been put forward for the quality of the water environment and the discharge standards of sewage treatment plants. More and more sewage treatment plants have adopted the requirements of the Class A A standard in the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB 18918-2002), and will even move closer to the surface water Class III and Class IV water standards. However, due to the widespread problem of insufficient carbon-nitrogen ratio, the removal of total nitrogen from sewage is often unable to meet increasingly stringent discharge standards. At present, external organic carbon sources (sodium acetate, glacial acetic acid, etc.) are usually added to meet the needs of the traditional heterotrophic denitrification process, which greatly increases the operating cost and complexity of operation and maintenance. Therefore, the autotrophic denitrification process using inorganic elements such as sulfur, iron or ferrous iron as electron donors has received more and more attention. The most intuitive manifestation is the autotrophic denitrification process based on materials such as sulfur and reduced iron powder. However, these materials developed solely based on the autotrophic denitrification process often have problems such as low denitrification efficiency and increased sulfate concentration in the effluent. In addition, existing carriers with carbon source slow-release functions often have problems such as uncontrollable carbon source release, which can easily cause problems such as effluent COD exceeding the standard, and need to be further improved.

Therefore, how to provide a stable, slow-release and efficient water denitrification material is an urgent problem for those skilled in the art to solve.

Contents of the invention

In view of this, the present invention provides a multi-layered structure mixotrophic extreme denitrification carrier and its preparation and application. The multi-layer structure compound trophic extreme denitrification carrier is a sulfur matrix-organic matter composite system. The organic matter is not only It can provide carbon source for heterotrophic denitrification, and can also provide electrons and energy for the denitrification metabolism and growth of ferroautotrophic denitrifying bacteria. The denitrification system equipped with this multi-layer structure mixotrophic extreme denitrification carrier does not require the addition of carbon. source, and the denitrification efficiency is greatly enhanced compared to the autotrophic denitrification process alone; the multi-layer structure composite nutrient denitrification carrier is suitable for typical sewage treatment and water quality such as biological fluidized beds, biological filters, and constructed wetlands. Purification system.

In order to achieve the above objects, the present invention adopts the following technical solutions:

First, the present invention provides a multi-layer structure mixotrophic extreme denitrification carrier, the carrier has a core-shell structure, including an inorganic core and an organic shell;

The inorganic core includes autotrophic functional materials and buffer materials;

The organic shell includes alternately arranged layers of heterotrophic functional materials and layers of structural components;

The mass ratio of the inorganic core, heterotrophic functional material layer and structural component layer is (6~8): (2~3): (1~3);

The inorganic core is in contact with the heterotrophic functional material layer.

Polyhydroxyalkanoate (PHA) can provide carbon sources while guiding the evolution of denitrification functional bacteria in the microbial community, quickly enhancing the denitrification performance of the water purification system.

Preferably, the autotrophic functional material is sulfur, and the buffer material is one of calcite, aragonite and dolomite.

Sulfur serves as an electron donor to participate in the sulfur autotrophic denitrification process. The buffer material can provide calcium ions to reduce the residual sulfate produced by sulfur autotrophic denitrification in the effluent, and adjust the overall density of the carrier.

Further, the mass ratio of the autotrophic functional material to the buffer material is (3-7): (1-3).

Preferably, the heterotrophic functional material is polyhydroxyalkanoate, and the structural component is a mixture of adhesive and foaming agent with a mass ratio of (2-5):1.

Further, the adhesive is polylactic acid, and the foaming agent is one of sodium α-alkenesulfonate, azodicarbonamide, and AES synthetic protein.

The invention also provides a method for preparing a multi-layered structure mixotrophic extreme denitrification carrier as described in the above technical solution, which includes the following steps:

Step 1: Preparation of inorganic core

Mix the autotrophic functional material and the buffer material in proportion, stir and heat to melt, then drop it into cold water for cooling and granulation to obtain the inorganic core;

Step Two: Organic Shell Loading

The inorganic core obtained in step 1 is first placed in the molten heterotrophic functional material, and the surface is wrapped with the heterotrophic functional material and then cooled and shaped. Then it is placed in the molten structural component, and the surface is wrapped with the structural component and then cooled and shaped. Repeat the operation to make it The inorganic core is coated with a layer of heterotrophic functional materials and a layer of structural components, that is, a multi-layered structure of a mixotrophic extreme denitrification carrier.

Preferably, in step one, the stirring speed is 200-350 rpm, the stirring time is 300-600 s, and the heating temperature is 170°C-180°C.

Preferably, in step two, the heterotrophic functional materials and structural components are kept in a molten state at a temperature of 130-180°C; cooling water is used for cooling and shaping, and the temperature is 40-75°C.

Preferably, the organic shell loading operation in step two is repeated 2 to 5 times.

In addition, the present invention also provides the multi-layer structure mixotrophic extreme denitrification carrier described in the above scheme and the application of the multi-layer structure mixotrophic extreme denitrification carrier prepared by the method described in the above scheme, which is applied to C/ In the treatment of water with N≤3 and TN≤15mg/L.

Preferably, the particle size of the inorganic core granulation is determined according to the application scenario of the multi-layer structure mixotrophic extreme denitrification carrier. In common application scenarios, the recommended material size in the biological fluidized bed system is d=1~3mm, and the biological filter The recommended material size in the pool system is d=2~15mm, and the recommended material size in the constructed wetland system is d=10~50mm.

It can be seen from the above technical solution that compared with the existing technology, the present invention provides a multi-layer structure mixotrophic extreme denitrification carrier and its preparation and application, which has the following beneficial effects:

1) The traditional biological denitrification process often requires the sewage to have a high C/N to ensure the progress and effect of the denitrification process, so it is often necessary to add external organic carbon sources such as sodium acetate. Without the need for external addition of organic carbon sources, the present invention mainly relies on the sulfur autotrophic-heterotrophic complex nutritional denitrification process to achieve efficient and deep denitrification of low-nitrogen polluted sewage with C/N≤3, effectively improving water quality. Nitrogen removal efficiency of the purification system.

2) The present invention uses a calcium ion buffering strategy to reduce the impact of sulfate by-products in the sulfur autotrophic denitrification process, and simultaneously uses a polylactic acid-PHA alternating multi-layer structure to control the slow release rate of autotrophic and heterotrophic functional materials, thereby avoiding denitrification. The concentration of sulfates and organic matter in the nitrogen system effluent is too high, causing secondary pollution.

3) The present invention adopts a multi-layer structure of an outer layer of autotrophic functional material and an inner layer of autotrophic functional material. The outer layer of PHA quickly intervenes in the denitrification process to guide the succession of the denitrification functional bacterial community, and then turns to autotrophic-heterotrophic. The compound trophic denitrification process has better overcome the problems of slow start and low denitrification load of the autotrophic denitrification process.

4) The present invention can be widely adapted to typical water purification scenarios represented by biological fluidized beds, biological filters, and artificial wetlands, and has the advantages of low cost, simple preparation, and good hydraulic performance.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without exerting creative efforts.

Figure 1 is a schematic diagram of the preparation process of a multi-layer structure mixotrophic extreme denitrification carrier of the present invention;

Figure 2 is a schematic diagram of the application of a multi-layer structure mixotrophic extreme denitrification carrier in a biological fluidized bed in Embodiment 1 of the present invention;

Figure 3 is a schematic diagram of the application of a multi-layer structure mixotrophic limit denitrification carrier in a biological filter in Embodiment 2 of the present invention;

Figure 4 is a schematic diagram of the application of the multi-layer structure mixotrophic extreme denitrification carrier in constructed wetlands in Embodiment 3 of the present invention;

In the picture, 1-multi-layer structure mixotrophic extreme denitrification carrier, 2-aeration tube, 3-water inlet, 4-outlet tank, 5-water outlet, 6-supporting layer, 7-aquatic plants, 8-rough Sand layer, 9-water distribution pipe, 10-anti-seepage layer.

Detailed ways

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

As shown in Figure 1, the preparation method of a multi-layer structure mixotrophic extreme denitrification carrier includes the following steps:

Step 1: Preparation of inorganic core

Mix the autotrophic functional material sulfur and the buffer material calcium carbonate mineral according to the mass ratio (3~7): (1~3), then stir at 200~350rpm for 300~600s, and at the same time heat and melt at 170℃~180℃ before adding dropwise Cool and granulate in cold water (40°C) to obtain the inorganic core;

Step Two: Organic Shell Loading

The inorganic core obtained in step 1 is first placed in the heterotrophic functional material polyhydroxyalkanoate (PHA) maintained in a molten state at 130-180°C, the surface is wrapped with the polyhydroxyalkanoate (PHA), then cooled and shaped, and then placed Among the structural components composed of polylactic acid and foaming agent in a molten state at 130~180℃ at a mass ratio of (2~5):1, the structural components are wrapped on the surface and placed in cooling water (40~75℃) , repeated operations make the inorganic core coated with a heterotrophic functional material layer and a structural component layer, that is, a multi-layer structure mixotrophic extreme denitrification carrier;

The foaming agent is one of sodium α-alkenesulfonate, azodicarbonamide, and AES synthetic protein.

The multi-layer structure mixotrophic extreme denitrification carrier prepared by the above method is specifically prepared and applied as follows:

Example 1

The autotrophic functional material sulfur and the buffer material calcium carbonate mineral aragonite are mixed in a mass ratio of 5:2 to obtain the inorganic core component;

Polylactic acid and azodicarbonamide are mixed at a mass ratio of 5:1 to obtain structural components;

The mass ratio of inorganic core, autotrophic functional materials and structural components is 6:2:1;

The heating temperature of the melting step of the inorganic core is 175℃~180℃, the stirring speed is 300~350rpm, the stirring time is 550~600s, and the granulation size d=1~5mm;

The organic shell is compounded to the outer layer of the inorganic core through alternating loading of heterotrophic functional materials and structural components. The heterotrophic functional materials and structural components are maintained in a molten state at 165-170°C respectively; the alternating loading process involves using the inorganic core first After dipping the PHA, place it in cooling water (40°C) to set the shape, and after dipping the structural components, place it again in cooling water to set the shape. Repeat the above steps 5 times as needed.

The prepared multi-layer structure mixotrophic extreme denitrification carrier is loaded into a biological fluidized bed, as shown in Figure 2, and is operated in an upflow mode to achieve sewage treatment plant tail water ( TN≤15mg/L, C/N≤3), especially the highly efficient and in-depth treatment of nitrate nitrogen, the effluent water quality reaches the surface Class III water standard (TN≤1.0mg/L; COD≤20mg/L).

Example 2

The autotrophic functional material sulfur and the buffer material calcium carbonate mineral calcite are mixed in a mass ratio of 3:1 to obtain the inorganic core component;

Polylactic acid and sodium α-alkenesulfonate are mixed at a mass ratio of 5:1 to obtain structural components;

The mass ratio of inorganic core, autotrophic functional materials and structural components is 8:3:3;

The heating temperature of the melting step of the inorganic core is 170℃~175℃, the stirring speed is 200~300rpm, the stirring time is 300~400s, and the granulation size d=2~15mm;

The organic shell is compounded to the outer layer of the inorganic core through alternating loading of heterotrophic functional materials and structural components. The heterotrophic functional materials and structural components are maintained in a molten state at 170 to 180°C respectively. The alternating loading process uses the inorganic core first. After dipping the PHA, place it in cooling water (40°C) to set the shape, and after dipping the structural components, place it again in the cooling water to set the shape. Repeat the above steps 3 times as needed.

The prepared multi-layer structure mixotrophic extreme denitrification carrier is loaded into the denitrification biological filter, as shown in Figure 3. It adopts upflow operation to realize the treatment of sewage plant tail water through the heterotrophic-sulfur autotrophic denitrification process. (TN=8～12mg/L, C/N≤3), the effluent water quality reaches the surface Class III water standard (TN≤1.0mg/L; COD≤20mg/L).

Example 3

The difference from Example 2 is that the granulated particle size of the inorganic core is d=10~50mm, and the prepared multi-layer structure mixotrophic extreme denitrification carrier is laid in the artificial wetland, as shown in Figure 4. It operates in the upstream subsurface flow mode and uses the heterotrophic-sulfur autotrophic denitrification process to purify the surface water with low nitrogen pollution (TN≤5mg/L) and low carbon-to-nitrogen ratio (C/N≤3) in the wetland, and improve the effluent water quality. It reaches the surface level III water standard (TN≤1.0mg/L; COD≤20mg/L).

Each embodiment in this specification is described in a progressive manner. Each embodiment focuses on its differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple. For relevant details, please refer to the description in the method section.

The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be practiced in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The multilayer structure mixed nutrition type limit denitrification carrier is characterized in that the carrier is of a core-shell structure and comprises an inorganic core and an organic shell;

the inorganic core comprises an autotrophic functional material and a buffer material;

the organic shell comprises heterotrophic functional material layers and structural component layers which are alternately arranged;

the mass ratio of the inorganic core to the heterotrophic functional material layer to the structural component layer is (6-8): (2-3): (1-3);

the inorganic core is in contact with the layer of heterotrophic functional material.

2. The multi-layer structured mixed nutrient type extreme denitrification carrier according to claim 1, wherein the autotrophic functional material is sulfur, and the buffer material is one of calcite, aragonite and dolomite.

3. The multi-layered structured mixed nutrient type limiting denitrification carrier according to claim 1 or 2, wherein the mass ratio of the autotrophic functional material to the buffer material is (3-7): (1-3).

4. The multi-layer structure mixed nutrition type limit denitrification carrier according to claim 1, wherein the heterotrophic functional material is polyhydroxyalkanoate, and the structural components are binder and foaming agent in mass ratio (2-5): 1.

5. The multi-layered structure mixed nutrient type extreme denitrification carrier according to claim 4, wherein the binder is polylactic acid, and the foaming agent is one of alpha-sodium alkenyl sulfonate, azodicarbonamide and AES synthetic protein.

6. A method for preparing the multi-layered structured mixed nutrient type limiting denitrification carrier according to any one of claims 1 to 5, comprising the steps of:

step one: preparation of inorganic cores

Mixing the autotrophic functional material and the buffer material in proportion, stirring, heating, melting, dripping into cold water, cooling and granulating to obtain an inorganic core;

step two: organic housing load

And (3) firstly placing the inorganic core obtained in the step (A) in a molten heterotrophic functional material, coating the heterotrophic functional material on the surface, cooling and shaping, then placing the inorganic core in a molten structural component, coating the structural component on the surface, cooling and shaping, and repeating the operation to coat the heterotrophic functional material layer and the structural component layer outside the inorganic core, thus obtaining the multi-layer structure mixed nutrition type limiting denitrification carrier.

7. The method for preparing a multi-layered mixed nutrient type carrier for limiting nitrogen removal as claimed in claim 6, wherein in the first step, the stirring speed is 200-350 rpm, the stirring time is 300-600 s, and the heating temperature is 170-180 ℃.

8. The method for preparing a multi-layer structure mixed nutrient type extreme denitrification carrier according to claim 6, wherein the heterotrophic functional material and the structural component in the second step are kept in a molten state, and the temperature is 130-180 ℃; cooling water is adopted for cooling and shaping, and the temperature is 40-75 ℃.

9. The method for preparing a multi-layered structure mixed nutrient type limiting denitrification carrier according to claim 6, wherein the organic shell is loaded and operated repeatedly for 2-5 times in the second step.

10. The use of the multi-layer structure mixed nutrient type limit denitrification carrier according to any one of claims 1 to 5 and the multi-layer structure mixed nutrient type limit denitrification carrier prepared by the preparation method according to any one of claims 6 to 9, which is characterized in that the carrier is applied to water treatment with C/N less than or equal to 3 and TN less than or equal to 15 mg/L.