Denitrification nitrogen removal reactor, nitrogen removal method and application

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a denitrification reactor, a denitrification method and application. The denitrification nitrogen removal reactor comprises a denitrification nitrogen removal reactor body, wherein a water distribution pipe, a filler layer and a water collection device are sequentially arranged in the denitrification nitrogen removal reactor body from bottom to top; one end of the water distributor communicates with the pulsed water source; filler in the filler layer comprises a hydrophilic sulfenyl denitrification electron donor; and the particle size of the hydrophilic sulfenyl denitrification electron donor is 0.5-1.5 mm. According to the invention, a hydrophilic sulfenyl denitrification electron donor with a specific particle size is adopted as a filler, pulse water feeding is adopted, periodic hydraulic disturbance is generated in the reactor, and filler particles are pushed to generate pulse fluidization, so that efficient denitrification nitrogen removal treatment is realized, and the nitrogen removal efficiency can exceed 90%. Meanwhile, the denitrifying nitrogen removal reactor is simple in structure, easy to maintain and suitable for small and medium-sized sewage stations and distributed nitrogen removal scenes.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wastewater treatment, and particularly relates to a denitrification reactor, a denitrification method and application. BACKGROUND

[0002] At present, the main forms of biological denitrification reactors are denitrification reactors using suspended activated sludge, such as anoxic activated sludge bioreactors, and denitrification reactors using biological membranes, such as anoxic biological filter reactors. The electron donors consumed in the denitrification reactions of the above reactors are mainly soluble organic substances that can be utilized by microorganisms, such as soluble organic pollutants in wastewater, artificially added glucose, acetic acid, methanol and the like. With the consumption of denitrification electron donors, the proportion of denitrification electron donors in the cost of wastewater treatment is large, and it is a realistic demand to find other substances that can be used for biochemical denitrification at low cost.

[0003] Sulfur is increasingly concerned by people due to its low unit operation cost and easy availability of raw materials. At present, the denitrification reactors using sulfur as an electron acceptor (such as sulfur) on the market mainly adopt the form of biological filter bed. Since the biological filter bed has the disadvantages of complex structure (not suitable for the modification of old biochemical pools mainly based on activated sludge method), poor resistance to suspended solids in influent, poor resistance to high salt and poor resistance to high hardness, the related technology can only be used for advanced treatment of wastewater, such as tertiary treatment, and the investment cost and operation cost are relatively high. In addition, since the sulfur-based denitrification reactor in the form of filter bed uses relatively smooth sulfur surface and the surface properties are hydrophobic, the denitrification biofilm is not easy to attach and grow on the surface of the filler, and is easy to be detached due to hydraulic impact, resulting in system failure. The above reasons limit the application of the related technology. SUMMARY

[0004] The present application aims to solve one or more technical problems in the prior art, and at least provide a beneficial alternative. Specifically, the present application provides a denitrification reactor using a hydrophilic sulfur-based denitrification electron donor as a filler to perform denitrification reaction on wastewater containing nitrate in an intermittent fluidization manner, which has good denitrification efficiency, and the influent of the denitrification reactor is not affected by the content of suspended solids and hardness, and the salt tolerance and investment cost are superior to those of the filter bed reactor.

[0005] The inventive concept of the present application: the denitrification reactor of the present application comprises a denitrification reactor body, a water distribution pipe, a filler layer and a water collecting device are sequentially arranged in the denitrification reactor body from bottom to top; one end of the water distribution pipe is communicated with a pulse water source; the filler in the filler layer comprises a hydrophilic sulfur-based denitrification electron donor; the particle size of the hydrophilic sulfur-based denitrification electron donor is 0.5-1.5 mm. The hydrophilic sulfur-based denitrification electron donor with a specific particle size is used as the filler, and the pulse water feeding is used to generate periodic hydraulic disturbance in the denitrification reactor, to push the pulse fluidization of the filler particles, to make the hydrophilic sulfur-based denitrification electron donor generate regular floating, sinking or local suspension state, and to realize efficient denitrification treatment.

[0006] Therefore, the first aspect of the present application provides a denitrification reactor.

[0007] Specifically, the denitrification reactor comprises a denitrification reactor body, a water distribution pipe, a filler layer and a water collecting device are sequentially arranged in the denitrification reactor body from bottom to top;

[0008] One end of the water distribution pipe is communicated with a pulse water source.

[0009] The filler in the filler layer comprises a hydrophilic sulfur-based denitrification electron donor.

[0010] The particle size of the hydrophilic sulfur-based denitrification electron donor is 0.5-1.5 mm.

[0011] Preferably, the pulse water source is provided by a water inlet pump or a pulse generator.

[0012] Preferably, the other end of the water distribution pipe is connected with a emptying valve.

[0013] Preferably, the water distribution pipe is an independent water pipe or a perforated pipe.

[0014] Preferably, the water distribution pipe is in a ring shape or a Heng shape.

[0015] Specifically, the pulse water feeding is realized by the pulse mode of the water inlet pump working-intermittent-working, or by the pulse generator, the water inlet enters the denitrification reactor from the bottom through the water distribution pipe, flows through the filler layer in an upward flow mode, pushes the pulse fluidization of the hydrophilic sulfur-based denitrification electron donor particles in the filler layer, the surface of the hydrophilic sulfur-based denitrification electron donor has denitrification microorganisms, the nitrate nitrogen in the wastewater is adsorbed in the filler layer and is fully reduced to nitrogen gas under the metabolic action of the microorganisms, the nitrogen gas escapes through the liquid surface or escapes with the liquid to the gas phase.

[0016] The denitrification mechanism of the present application is that: in the process of pulse fluidization, the surface of the hydrophilic sulfur-based denitrification electron donor provides an electron donor (sulfur), the microorganisms utilize NO3- or NO2 - As an electron acceptor, it completes the denitrification reduction reaction, with typical reactions as follows:

[0017] 5S 0 +6NO3 - +2H₂O→3N₂+5SO₄ 2- +4H + .

[0018] Preferably, the packing layer has a volume fraction of 10-60% within the denitrification reactor body.

[0019] Preferably, the hydrophilic sulfur-based denitrification electron donor comprises modified particulate sulfur.

[0020] The modified particulate sulfur is sulfur modified with a nonionic surfactant.

[0021] Preferably, the nonionic surfactant comprises polysorbate; more preferably, the nonionic surfactant comprises polysorbate 80 (Tween 80).

[0022] Preferably, the modified particulate sulfur is obtained by mixing a nonionic surfactant and sulfur, and then heating.

[0023] More preferably, the preparation process of the modified granular sulfur is as follows:

[0024] First, sulfur and water are mixed to obtain a slurry. Then, the slurry and a nonionic surfactant are mixed and heated to obtain the final product.

[0025] Preferably, the amount of the nonionic surfactant is 1.5-2.5% of the mass of the sulfur; more preferably, the amount of the nonionic surfactant is 1.8-2.2% of the mass of the sulfur; and even more preferably, the amount of the nonionic surfactant is 2% of the mass of the sulfur.

[0026] Preferably, the heating temperature is 100-125℃ and the heating time is 0.1-10h; more preferably, the heating temperature is 105-120℃ and the heating time is 0.2-3.5h; even more preferably, the heating temperature is 114℃ and the heating time is 2h.

[0027] Preferably, the surface of the hydrophilic sulfur-based denitrifying electron donor is covered with denitrifying microorganisms.

[0028] Specifically, this invention does not impose any particular limitation on the specific types of denitrifying microorganisms, which can be selected according to actual needs.

[0029] Preferably, the water collection device includes a water collection weir or a perforated water collection pipe.

[0030] Preferably, the water collection device consists of two rows of evenly arranged perforated water collection pipes connected to the water outlet pipe to collect the treated wastewater.

[0031] Preferably, the denitrification reactor further includes a waste gas discharge device located at the top of the denitrification reactor body.

[0032] Preferably, the cross-sectional shape of the denitrification reactor body includes a circle, a square, or other regular shapes.

[0033] Preferably, the material of the denitrification reactor body includes polypropylene or stainless steel.

[0034] A second aspect of the present invention provides a denitrification method.

[0035] Specifically, the denitrification method involves treating wastewater using the denitrification reactor described in the first aspect of this invention, comprising the following steps:

[0036] Nitrogenous wastewater enters the bottom of the denitrification reactor body through the distribution pipe in a pulse influent manner, undergoes denitrification through the packing layer, and then flows out of the denitrification reactor through the water collection device.

[0037] Preferably, the pulse mode of the pulsed water intake is 10-15 seconds of operation followed by an interval of 300-420 seconds.

[0038] Preferably, during denitrification, the system operates at a temperature of 8-35℃ and a pH of 6.5-8.5, which is suitable for the growth of conventional denitrifying bacteria.

[0039] Preferably, the denitrification reactor can be operated continuously or intermittently, with each complete hydraulic retention time being 2-6 hours, adjusted according to the nitrate nitrogen concentration in the wastewater.

[0040] A third aspect of the present invention provides an application of the denitrification reactor described in the first aspect of the present invention in wastewater treatment.

[0041] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0042] (1) The present invention uses a hydrophilic sulfur-based denitrifying electron donor with a specific particle size as a filler, and at the same time adopts pulsed water inlet to generate periodic hydraulic disturbances inside the denitrifying reactor, promoting pulsed fluidization of the filler particles, making the hydrophilic sulfur-based denitrifying electron donor exhibit regular floating, sinking or local suspension states, so as to achieve efficient denitrifying treatment. In addition, the structure of the denitrifying reactor of the present invention is simple and easy to maintain, suitable for medium and small sewage sites and distributed denitrification scenarios, with a high treatment load and few restrictive conditions for the influent water quality, and is particularly suitable for retrofitting denitrification reactions using recycled structures.

[0043] (2) The hydrophilic sulfur-based denitrifying electron donor of the present invention is stable and has a slow release property, without the need for an externally added organic electron donor; and it has good hydrophilicity on its surface, the system starts quickly, the biofilm adheres evenly, and it is not easy to float.

[0044] (3) The pulsed fluidization caused by the pulsed water inlet of the present invention helps to prevent blockage and promote biofilm renewal.

[0045] (4) The present invention adopts an upward flow structure to avoid short-circuit flow and improve the utilization rate of the reactor. Description of the Drawings

[0046] Figure 1 It is a schematic structural diagram of the denitrifying reactor of Embodiment 1 of the present invention. Detailed Embodiments

[0047] In order to make those skilled in the art more clearly understand the technical solutions described in the present invention, the following examples are listed for illustration. It should be noted that the following examples do not limit the scope of protection required by the present invention. <C

[0048] In the following examples, the raw materials, reagents or devices used, unless otherwise specified, can be obtained from conventional commercial channels or can be obtained by existing known methods.

[0049] Embodiment 1

[0050] The denitrifying reactor of Embodiment 1 is a vertically arranged cylindrical biochemical reactor, with a height of 1.5 meters, a diameter of <C 0.5 meters, and the material is polypropylene;

[0051] A perforated water distribution pipe is arranged at the bottom of the denitrifying reactor. The water distribution pipe is distributed in a cross shape, with a pore diameter of 1 - 1.5 cm. The water distribution pipe is wrapped with a porous mesh with a pore size of 0.1 mm to prevent the denitrifying electron donor from entering the water distribution pipe; one end of the water distribution pipe is connected to a water inlet pump, and the other end is equipped with an emptying valve for easy cleaning and maintenance;

[0052] The internal packing of the denitrification reactor consists of 40% granular hydrophilic sulfur-based denitrification electron donors, namely modified granular sulfur, as the packing layer. The modified granular sulfur is spherical with a particle size of 0.5-1.5 mm, hard in texture, and has a large specific surface area.

[0053] The surface of the modified granular sulfur is covered with denitrifying microorganisms;

[0054] The top of the denitrification reactor is equipped with a water collection device, which consists of two rows of evenly distributed perforated water collection pipes (i.e., perforated water collection pipes) connected to the outlet pipe to collect the treated wastewater.

[0055] Example 1: A schematic diagram of the denitrification reactor is shown below. Figure 1 As shown.

[0056] The method for preparing modified granular sulfur includes the following steps:

[0057] Powdered sulfur of 500-600 mesh was mixed with water to obtain a slurry with a solid content of 20%. The slurry was then poured into an enamel-lined high-pressure reactor, and the nonionic surfactant Tween80 was added at a dosage of 2% of the powdered sulfur mass. The stirring and heating of the enamel-lined high-pressure reactor were started, heated to 114°C and held for 2 hours. Then the heating was turned off while stirring was maintained. After the temperature of the enamel-lined reactor dropped to room temperature, the material was discharged, and the granular sulfur deposited at the bottom of the liquid was collected to obtain modified granular sulfur.

[0058] The denitrification method for treating wastewater using the above-mentioned denitrification reactor includes the following steps:

[0059] Nitrate nitrogen (NO3) - Wastewater with a NO3- concentration of 30 mg / L is injected into the bottom of the denitrification reactor via an influent pump in a pulse pattern of "12s operation followed by 360s intermittent operation". During each pulse cycle, water is injected into the bottom of the denitrification reactor through a distribution pipe, causing local pulsed fluidization of the modified granular sulfur and forming a turbulent zone. During the pulsed fluidization process, the surface of the granular sulfur-based electron donor provides electron donors (sulfur), and microorganisms utilize NO3-. - or NO2 - As an electron acceptor, nitrate nitrogen in wastewater is adsorbed and undergoes denitrification reduction reaction under the action of microbial metabolism, and is reduced to nitrogen gas. The nitrogen gas escapes through the liquid surface or escapes into the gas phase along with the liquid. The nitrogen gas and other gases generated during the operation are collected by the waste gas discharge device. The wastewater after denitrification treatment flows upward to the water collection device and is discharged from the denitrification reactor.

[0060] The system operates at a temperature of 23.8℃, maintains a pH of 7.7, and has a complete hydraulic residence time of 3.5 hours.

[0061] Under the above conditions, after 48 hours of continuous operation, the nitrate concentration in the effluent of the denitrification reactor dropped to 1.6 mg / L, the denitrification efficiency reached 96%, and the system operated stably without any problems such as sulfur particles floating, significant blockage, or frequent backwashing.

[0062] Example 2

[0063] The difference between Example 2 and Example 1 is that the denitrification reactor is filled with 20% by volume of granular hydrophilic sulfur-based denitrification electron donors.

[0064] Similarly, NO3 - Taking wastewater with a -N concentration of 30 mg / L as an example, and operating under the same conditions as in Example 1 for 48 hours, the nitrate concentration in the effluent of the denitrification reactor dropped to 3.1 mg / L, the denitrification efficiency reached 90%, and the system operated stably without problems such as sulfur particle floating, significant blockage, or frequent backwashing.

[0065] Example 3

[0066] The difference between Example 3 and Example 2 is that the influent NO3 - The -N concentration was 60 mg / L. After operating under the same conditions as in Example 2 for 48 hours, the nitrate concentration in the effluent of the denitrification reactor decreased to 6.8 mg / L, the denitrification efficiency reached 88%, and the system operated stably without problems such as sulfur particle floating, significant blockage, or frequent backwashing.

[0067] Comparative Example 1

[0068] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses unmodified sulfur as a filler, while the rest is the same as Example 1.

[0069] Similarly, NO3 - Taking wastewater with a -N concentration of 30 mg / L as an example, and operating under the same conditions as in Example 1 for 48 hours, the nitrate concentration in the effluent of the denitrification reactor dropped to 6.8 mg / L, with a denitrification efficiency of approximately 77%. Furthermore, during operation, some particulate sulfur particles had bubbles attached to their surfaces and floated to the surface, resulting in visible particulate sulfur particles in the effluent.

[0070] Comparative Example 2

[0071] The only difference between Comparative Example 2 and Example 1 is that the particle size of the modified granular sulfur in Comparative Example 2 is 0.5-1.5 cm, while the rest is the same as in Example 1.

[0072] Similarly, NO3 -Taking wastewater with a nitrogen concentration of 30 mg / L as an example, and operating under the same conditions as in Example 1 for 48 hours, the nitrate concentration in the effluent of the denitrification reactor dropped to 15.8 mg / L, with a denitrification efficiency of approximately 50%.

[0073] Comparative Examples 1 and 2 used unmodified sulfur as filler and modified granular sulfur with a particle size of 0.5-1.5 cm, respectively. The denitrification efficiency of Comparative Examples 1 and 2 was significantly reduced, indicating that the use of modified granular sulfur with a specific particle size plays an important role in improving denitrification efficiency.

[0074] In summary, this invention uses hydrophilic sulfur-based denitrifying electron donors of a specific particle size as packing material, and employs pulsed water inlet to generate periodic hydraulic disturbances inside the denitrification reactor. This causes the packing particles to undergo pulsed fluidization, resulting in the hydrophilic sulfur-based denitrifying electron donors exhibiting regular floating, sinking, or localized suspension states. This achieves highly efficient denitrification treatment with a denitrification efficiency exceeding 90%, and the system operates stably without issues such as sulfur particle floating, significant blockage, or frequent backwashing.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A denitrification reactor, characterized in that, The denitrification reactor includes a denitrification reactor body, and the denitrification reactor body is provided with a water distribution pipe, a packing layer and a water collection device from bottom to top; One end of the water distribution pipe is connected to a pulsed water source; The filler in the packing layer includes a hydrophilic sulfur-based denitrification electron donor; The hydrophilic sulfur-based denitrifying electron donor has a particle size of 0.5-1.5 mm.

2. The denitrification reactor according to claim 1, characterized in that, The pulsed water source is provided by an inlet pump or a pulse generator.

3. The denitrification reactor according to claim 1, characterized in that, The packing layer has a volume fraction of 10-60% within the denitrification reactor body.

4. The denitrification reactor according to claim 1, characterized in that, The hydrophilic sulfur-based denitrification electron donor includes modified particulate sulfur; and / or, the surface of the hydrophilic sulfur-based denitrification electron donor is coated with denitrifying microorganisms.

5. The denitrification reactor according to claim 4, characterized in that, The modified particulate sulfur is sulfur modified with a nonionic surfactant.

6. The denitrification reactor according to claim 5, characterized in that, The modified granular sulfur is obtained by mixing a nonionic surfactant and sulfur, and then heating the mixture.

7. The denitrification reactor according to claim 1, characterized in that, The water collection device includes a water collection weir or a perforated water collection pipe; and / or, the denitrification reactor further includes a waste gas discharge device located at the top of the denitrification reactor body.

8. The denitrification reactor according to claim 1, characterized in that, The cross-sectional shape of the denitrification reactor body includes circular, square, or other regular shapes.

9. A denitrification method, characterized in that, The denitrification reactor according to any one of claims 1-8 is used to treat wastewater for denitrification, comprising the following steps: Nitrogenous wastewater enters the bottom of the denitrification reactor body through the distribution pipe in a pulse influent manner, undergoes denitrification through the packing layer, and then flows out of the denitrification reactor through the water collection device.

10. The application of the denitrification reactor according to any one of claims 1-8 in wastewater treatment.

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