Method for regulating denitrification functional flora of micro-aerobic sludge bed and micro-aerobic sludge bed

Abstract

The invention relates to a method for regulating and controlling a denitrification functional flora of a micro-aerobic sludge bed and the micro-aerobic sludge bed, belongs to the technical field of sewage treatment, and solves the technical problems that the price is high and the flora is inflammable when commercial nanoscale zero-valent iron is adopted for regulating and controlling the flora, the release of iron ions is difficult to control when sponge iron is added and the like. Zero-valent iron which is greenly synthesized from agricultural wastes is added into the micro-aerobic sludge bed so as to regulate and control the denitrification functional flora of the micro-aerobic sludge bed. The micro-aerobic sludge bed comprises a reactor, a filler ball is placed in the reactor, and the filler ball comprises a shell and contents located in the shell; the content is loaded with zero-valent iron which is green synthesized from agricultural wastes. Zero-valent iron is synthesized through the extracts of the agricultural waste, the pollution risk in the preparation process is reduced, and the preparation cost is reduced. The defects that commercial nanoscale zero-valent iron lacks stability and is difficult to separate from a purified medium are overcome, particle aggregation is reduced, and the effectiveness of the zero-valent iron is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and specifically relates to a method for regulating denitrification functional bacterial flora in a microaerobic sludge bed and a microaerobic sludge bed. Background Art

[0002] Realizing energy conservation and consumption reduction in sewage treatment plants is an important measure to achieve carbon neutrality in sewage treatment plants. As an energy-intensive industry, sewage treatment plants account for 60% to 70% of total energy consumption in electricity consumption, among which nitrogen removal is the key and difficult part of sewage treatment. Most sewage treatment plants in my country use aerobic activated sludge as the core treatment method, and its aeration system consumes extremely high energy. Micro-aerobic denitrification process has been widely studied and applied because it only requires extremely low dissolved oxygen. However, in the micro-aerobic denitrification process, microorganisms grow slowly, the startup time is long, the content of functional bacteria is low, and the denitrification efficiency needs to be improved.

[0003] Iron has an enhancing effect on the activity of denitrifying microorganisms. Zero-valent iron can increase the activity of two nitrifying enzymes, ammonia monooxygenase and nitrite oxidase, of nitrifying bacteria, promote the denitrification ability of iron-type denitrifying bacteria and hydrogen autotrophic denitrifying bacteria, and promote the synthesis of heme in anaerobic ammonia oxidizing bacteria. Therefore, adding zero-valent iron to the micro-aerobic biological denitrification process can improve the denitrification efficiency. However, due to its magnetic properties and extremely high reducibility, zero-valent iron is easy to aggregate, precipitate, and oxidize, so it is difficult to control its position and state in the reactor. At present, there are roughly the following ways to add zero-valent iron: directly adding nano or micron-level zero-valent iron to water, or directly adding sponge iron. However, commercial-grade nano zero-valent iron is expensive and flammable, and directly adding sponge iron requires a large amount of addition and it is difficult to control the release of iron ions. Therefore, it is difficult to achieve the optimal concentration of zero-valent iron to promote denitrification microorganisms. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for regulating the denitrification functional bacterial flora of a microaerobic sludge bed and a microaerobic sludge bed, which solves the technical problems that the use of commercial-grade nano zero-valent iron to regulate the bacterial flora is expensive and flammable, and the use of sponge iron to add is difficult to control the release of iron ions.

[0005] In order to solve the above problems, the technical solution of the present invention is: a method for regulating the denitrification functional bacteria of a microaerobic sludge bed. In the startup stage, zero-valent iron greenly synthesized from agricultural waste is added to the microaerobic sludge bed to regulate the denitrification functional bacteria of the microaerobic sludge bed; for wastewater with a carbon-nitrogen ratio lower than 3 and an ammonia nitrogen concentration lower than 100 mg / L, green synthesized zero-valent iron carrying a hydroxyl and carboxyl group content greater than 60% is added.

[0006] Optionally, for wastewater with a carbon-nitrogen ratio greater than or equal to 3 and an ammonia nitrogen concentration higher than 100 mg / L, green synthesized zero-valent iron carrying a hydroxyl and carboxyl group concentration less than 30% is added.

[0007] Through the above settings, due to the different types and contents of the extracts of different abandoned crops as raw materials, the green synthesized zero-valent iron has differences in structure, iron content and other element contents, stability and removal efficiency, and has different effects on micro-aerobic activated sludge. Therefore, according to the different effects of zero-valent iron synthesized from extracts of different crops on micro-aerobic activated sludge, the difference is used to enrich and cultivate different functional bacterial communities, so that different denitrification functional bacterial communities have relatively fixed ecological niches in the micro-aerobic sludge bed for treating wastewater of different water qualities, thereby increasing the abundance of functional bacterial communities in different ecological niches, strengthening the cooperation between bacterial communities, and enhancing the denitrification efficiency in the micro-aerobic sludge bed. According to the characteristics of water quality, different types of green synthesized zero-valent iron are flexibly added to achieve the regulation of denitrification functional bacterial communities in micro-aerobic sludge beds suitable for different water qualities.

[0008] Optionally, the agricultural waste includes one of winery lees, persimmon peels, banana peels and grapefruit peels.

[0009] Optionally, the steps for preparing zero-valent iron synthesized green from agricultural waste include: Step 1, extracting reducing substances: crushing agricultural waste and mixing with water in a ratio of agricultural waste: water = 20g-50g: 1L, heating in a water bath at 50°C-80°C to prepare a polyphenol solution with reducing properties; Step 2, mixed reaction: add 0.05mol / L-0.2mol / L Fe 3+ or Fe 2+ The liquid is mixed with the same volume of polyphenol solution, and the Fe 3+ and Fe 2+ Reduced to zero-valent iron, thus generating nano zero-valent iron.

[0010] Optionally, the filler balls are immersed in the prepared zero-valent iron solution, taken out and then suspended in a micro-aerobic sludge bed for use.

[0011] Another object of the present invention is to provide a micro-aerobic sludge bed, comprising a reactor, in which filler balls are placed, the filler balls comprising an outer shell and contents located within the outer shell; the contents are made of a porous and water-absorbing material, and the contents are loaded with the above-mentioned zero-valent iron synthesized greenly from agricultural waste.

[0012] Optionally, the reactor is provided with a sewage inlet, a mud inlet, a water inlet and a water outlet; the water outlet is connected to the reflow tank.

[0013] Optionally, an outlet pipe is provided on the reflow pool for partially aerated reflow water to flow out, the outlet pipe is connected to the sewage inlet via a pipeline, and a reflow pump is arranged on the pipeline.

[0014] Optionally, there are a plurality of filler balls, and the plurality of filler balls are suspended in the reactor via connecting ropes, and adjacent filler balls are connected via connecting ropes.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. Zero-valent iron synthesized from agricultural waste can efficiently remove pollutants such as nitrates in sewage and improve the pollutant removal efficiency of effluent.

[0016] 2. Green synthetic zero-valent iron has higher environmental protection, economy, efficiency and stability, and has good biocompatibility with the activated sludge in the micro-aerobic sludge bed.

[0017] 3. The working principle of the method for regulating the functional bacterial flora of microaerobic sludge bed denitrification of the present invention is: due to the different types and concentrations of reducing substances extracted from different agricultural wastes, the green synthesized zero-valent iron has different crystal forms, different hydroxyl and carboxyl contents, and different particle sizes, specific surface areas and surface charges. Therefore, the effects on the functional microorganisms in the activated sludge are different, and different functional microorganisms are suitable for the treatment of different water qualities. Therefore, the present invention achieves the enrichment of functional bacterial flora suitable for different water qualities by immersing the absorbent sponge or polyurethane in the zero-valent iron filler ball into zero-valent iron of different structures.

[0018] 4. The present invention synthesizes zero-valent iron through extracts from agricultural waste. Since the use of toxic traditional reducing agents such as borohydride and hydrazine is avoided, the pollution risk in the preparation process is reduced, a green and environmentally friendly preparation process is achieved, and the preparation cost is reduced. In addition, the green synthetic nano zero-valent iron has low toxicity and good biocompatibility, avoiding some shortcomings of commercial-grade nano zero-valent iron itself, such as lack of stability and difficulty in separation from the purified medium, reducing particle agglomeration and improving the effectiveness of zero-valent iron. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the zero-valent iron-upflow sludge bed micro-aerobic denitrification process in Example 4; Figure 2 It is a cross-sectional view of the zero-valent iron-upflow sludge bed micro-aerobic denitrification process in Example 4; Figure 3 This is a schematic diagram of the connection between the reactor and the reflux tank in Example 4.

[0020] Figure numerals: 1, reactor; 11, sewage inlet; 12, mud intake; 13, water intake; 14, water outlet; 2, packing balls; 21, shell; 22, contents; 3, reflow tank; 31, outlet pipe; 4, reflow pump; 41, pipeline; 5, connecting rope. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0022] Example 1: This example provides a method for regulating the denitrification functional bacteria in a microaerobic sludge bed. During the startup phase, zero-valent iron greenly synthesized from agricultural waste is added to the microaerobic sludge bed to regulate the denitrification functional bacteria in the microaerobic sludge bed.

[0023] In this embodiment, 40 g of grape seed waste was added to 1 L of water and heated at 70° C. for 2 hours. After filtration, 0.2 M ferric chloride solution was added to the supernatant. After the solution reacted and turned black, the filler balls were placed in the solution for 3 minutes, and then the filler balls loaded with zero-valent iron solution were hung in the reactor.

[0024] The influent is wastewater with a COD concentration of 70 mg / L, a carbon-nitrogen ratio of 2, and an ammonia nitrogen concentration of 35 mg / L. The influent pump pumps the wastewater into the reactor from the reactor inlet. The wastewater flows through the reactor and the packing balls loaded with zero-valent iron. The zero-valent iron promotes the activity of microorganisms to complete the metabolism of microorganisms and achieve the purpose of wastewater treatment. The treated water flows into the reflow tank from the reactor outlet. After the effluent is fully aerated in the reflow tank, the reflow pump returns part of the fully aerated reflow water and the influent water from the reactor inlet to the reactor for oxygen supply. The remaining water is discharged. The discharged water has a COD concentration of 20 mg / L, an ammonia nitrogen concentration of 3 mg / L, and a TN concentration of 10 mg / L.

[0025] Zero-valent iron is used to promote the biological activity of microaerobic microorganisms. At the same time, zero-valent iron fillers provide a place for microaerobic microorganisms to attach and grow, thereby accelerating the removal of pollutants in wastewater.

[0026] During the startup phase, zero-valent iron greenly synthesized from agricultural waste was added to the micro-aerobic sludge bed. When treating wastewater with a carbon-nitrogen ratio lower than 3 and an ammonia-nitrogen concentration lower than 100 mg / L, green synthesized zero-valent iron carrying more hydroxyl and carboxyl groups was added. This effectively alleviated the problem of sludge swelling when treating wastewater with a low carbon-nitrogen ratio and low ammonia-nitrogen concentration, increased the sludge particle size, and the hydroxyl groups of the green synthesized zero-valent iron could interact with the phospholipid molecules in the cell membrane, causing changes in the arrangement of the phospholipid molecules, thereby affecting the permeability and fluidity of the cell membrane, increasing the content of iron ions outside the cell membrane entering the cell, and increasing the abundance and activity of autotrophic bacteria.

[0027] Example 2: This example provides a method for regulating the denitrification functional flora of a microaerobic sludge bed. A wastewater experiment with a carbon-nitrogen ratio of 3 and an ammonia nitrogen concentration higher than 100 mg / L was conducted in the same microaerobic sludge bed as in Example 1. 50 g of grapefruit peel waste was added to 1 L of water, heated at 70 ° C for 2 hours, filtered, and 0.1 M ferric chloride solution was added to the supernatant. After the solution reacted and turned black, the filler balls were placed in the solution for 3 minutes, and then the filler balls loaded with zero-valent iron solution were hung in the reactor.

[0028] The inlet conditions were changed to wastewater with a COD concentration of 330 mg / L, a carbon-nitrogen ratio of 3, and an ammonia nitrogen concentration of 110 mg / L. The inlet pump pumped the wastewater into the reactor from the inlet of the reactor, and it flowed through the reactor and the filler balls loaded with zero-valent iron. The zero-valent iron promoted the activity of microorganisms to complete the metabolism of microorganisms and achieve the purpose of wastewater treatment. The treated water flowed into the reflow tank from the outlet. After the outlet water was fully aerated in the reflow tank, the reflow pump pumped part of the fully aerated reflow water together with the inlet water back to the reactor from the inlet for oxygen supply, and the remaining water was discharged. The COD concentration of the discharged water was 30 mg / L, the ammonia nitrogen concentration was 4.2 mg / L, and the TN concentration was 12 mg / L.

[0029] Zero-valent iron is used to promote the biological activity of microaerobic microorganisms. At the same time, zero-valent iron fillers provide a place for microaerobic microorganisms to attach and grow, thereby accelerating the removal of pollutants in wastewater.

[0030] In the startup phase, zero-valent iron synthesized from agricultural waste is added to the micro-aerobic sludge bed. When treating wastewater with a carbon-nitrogen ratio of 3 and an ammonia nitrogen concentration higher than 100 mg / L, the carbon-nitrogen ratio meets the requirements of heterotrophic denitrification, and the denitrification effect is good. Therefore, the problem in the micro-aerobic sludge bed is mainly the problem of easy expansion of sludge under micro-aerobic conditions. In this embodiment, the polyphenol content in grapefruit peel is relatively low, and the synthesized zero-valent iron carries fewer hydroxyl and carboxyl groups, but grapefruit peel contains a variety of minerals and trace elements, such as calcium, magnesium, phosphorus, zinc, copper, and manganese. The addition of zero-valent iron synthesized from grapefruit peel can not only provide trace elements for activated sludge, but also effectively alleviate the problem of easy expansion of sludge under micro-aerobic conditions, thereby increasing the removal efficiency.

[0031] Example 3: This example provides a method for regulating the denitrification functional flora of a microaerobic sludge bed. A wastewater experiment with a carbon-nitrogen ratio greater than 3 and an ammonia nitrogen concentration greater than 100 mg / L was conducted in the same microaerobic sludge bed as in Example 1. 40 g of grapefruit peel waste was added to 1 L of water, heated at 80°C for 2 hours, filtered, and 0.1 M ferric chloride solution was added to the supernatant. After the solution reacted and turned black, the filler balls were placed in the solution for 3 minutes, and then the filler balls loaded with zero-valent iron solution were hung in the reactor.

[0032] The inlet conditions were changed to wastewater with a COD concentration of 385 mg / L, a carbon-nitrogen ratio of 3.5, and an ammonia nitrogen concentration of 110 mg / L. The inlet pump pumped the sewage into the reactor from the inlet, passing through the micro-aerobic sludge bed and zero-valent iron filler balls. The zero-valent iron promoted the activity of microorganisms to complete the metabolism of microorganisms and achieve the purpose of sewage treatment. The treated water flowed into the reflow tank from the outlet. After the effluent was fully aerated in the reflow tank, the reflux pump pumped part of the fully aerated return water together with the inlet water back to the reactor from the inlet for oxygen supply, and the remaining water was discharged. The COD concentration of the discharged water was 37 mg / L, the ammonia nitrogen concentration was 3.7 mg / L, and the TN concentration was 10.2 mg / L.

[0033] Example 4: Figure 1-Figure 3 As shown, this embodiment provides a micro-aerobic sludge bed, including a reactor 1, in which filler balls 2 are placed, and the filler balls 2 include an outer shell 21 and contents 22 located in the outer shell 21; the contents 22 are made of a porous and water-absorbing material, and the contents 22 are loaded with zero-valent iron greenly synthesized from agricultural waste as described in any one of Examples 1-3.

[0034] In a micro-aerobic sludge bed of this embodiment, the reactor 1 has a sewage inlet 11 , a sludge intake 12 , a water intake 13 and a water outlet 14 ; the water outlet 14 is connected to the reflow tank 3 .

[0035] In a micro-aerobic sludge bed of this embodiment, an outlet pipe 31 for partially aerated return water to flow out is provided on the return pool 3, and the outlet pipe 31 is connected to the sewage inlet 11 through a pipeline 41, and a return pump 4 is arranged on the pipeline 41.

[0036] In a micro-aerobic sludge bed of this embodiment, there are a plurality of filler balls 2 , and the plurality of filler balls 2 are suspended in the reactor 1 via connecting ropes 5 , and adjacent filler balls 2 are connected via connecting ropes 5 .

[0037] In a micro-aerobic sludge bed of this embodiment, the diameter of the reactor 1 is 10 cm and the height is 50 cm.

[0038] In a micro-aerobic sludge bed of this embodiment, the outer shell 21 is made of plastic material, and the content 22 is sponge or polyurethane, etc., which uses its porous properties to load zero-valent iron.

Claims

1. A method for regulating the denitrification functional bacteria in a microaerobic sludge bed, characterized in that: During the startup phase, zero-valent iron greenly synthesized from agricultural waste is added to the microaerobic sludge bed to regulate the denitrification functional bacteria of the microaerobic sludge bed; for wastewater with a carbon-nitrogen ratio lower than 3 and an ammonia nitrogen concentration lower than 100 mg / L, green synthesized zero-valent iron with a hydroxyl and carboxyl group content greater than 60% is added.

2. The method for regulating the denitrification functional bacteria in a microaerobic sludge bed according to claim 1, characterized in that: For wastewater with a carbon-nitrogen ratio greater than or equal to 3 and an ammonia nitrogen concentration higher than 100 mg / L, green synthetic zero-valent iron carrying a hydroxyl and carboxyl group concentration of less than 30% is added.

3. The method for regulating the denitrification functional bacteria in a microaerobic sludge bed according to claim 1, characterized in that: The agricultural waste includes one of winery lees, persimmon peels, banana peels and grapefruit peels.

4. The method for regulating the denitrification functional bacteria in a microaerobic sludge bed according to claim 1, characterized in that: The preparation steps of zero-valent iron synthesized from agricultural waste include: Step 1, extracting reducing substances: crushing agricultural waste and mixing with water in a ratio of agricultural waste: water = 20g-50g: 1L, heating in a water bath at 50°C-80°C to prepare a polyphenol solution with reducing properties; Step 2, mixed reaction: add 0.05mol / L-0.2mol / L Fe 3+ or Fe 2+ The liquid is mixed with the same volume of polyphenol solution, and the Fe 3+ and Fe 2+ Reduced to zero-valent iron, thus generating nano zero-valent iron.

5. The method for regulating the denitrification functional bacteria in a microaerobic sludge bed according to claim 2, characterized in that: The filler balls are immersed in the prepared zero-valent iron solution, taken out and hung in the micro-aerobic sludge bed for use.

6. A micro-aerobic sludge bed, characterized in that: The invention comprises a reactor (1), wherein a filler ball (2) is placed in the reactor (1), and the filler ball (2) comprises an outer shell (21) and contents (22) located in the outer shell (21); the contents (22) are made of a porous material having water-absorbing properties, and the contents (22) are loaded with zero-valent iron greenly synthesized from agricultural waste according to any one of claims 1 to 5.

7. A micro-aerobic sludge blanket according to claim 6, characterized in that: The reactor (1) is provided with a sewage inlet (11), a mud inlet (12), a water inlet (13) and a water outlet (14); The water outlet (14) is connected to the reflow pool (3).

8. A micro-aerobic sludge blanket according to claim 7, characterized in that: The reflow pool (3) is provided with an outlet pipe (31) for partially aerated reflow water to flow out, the outlet pipe (31) is connected to the sewage inlet (11) via a pipeline (41), and a reflow pump (4) is arranged on the pipeline (41).

9. A micro-aerobic sludge blanket according to claim 6, characterized in that: There are a plurality of filler balls (2), which are suspended in the reactor (1) via connecting ropes (5), and adjacent filler balls (2) are connected via connecting ropes (5).

Images