A device and method for electrolytically coupled synchronous denitrification and dephosphorization

Abstract

The present invention relates to a device and method for electrolytically coupled synchronous denitrification and phosphorus removal, wherein a coupling chamber and an electrolysis chamber are provided in a reactor, and the bottom of the coupling chamber has a hole for connecting the coupling chamber and the electrolysis chamber; the electrode plate of the electrolysis module is located in the electrolysis chamber, and the material of the electrode plate is iron, and the coupling chamber is filled with ecological fillers. The beneficial effects are as follows: electrolysis and ecological fillers are coupled, and when the mixed solution after electrolysis flows through the ecological fillers, on the one hand, the coupling effect caused by residual iron ions and iron hydroxides is utilized to improve the denitrification effect of the fillers, and at the same time, the growth of phosphorus removal microorganisms is induced to increase the biological phosphorus removal effect and strengthen the formation of biofilm, ultimately improving the denitrification effect while further purifying the residual phosphorus substances in the water, and overall achieving low-carbon and high-efficiency synchronous denitrification and phosphorus removal effects, achieving the purpose of synergistic efficiency in pollution reduction and carbon reduction, and on the other hand, the filtering and interception effect of the ecological fillers is utilized to prolong the reaction process, effectively achieve secondary removal of phosphorus, and reduce the turbidity and chromaticity of the effluent.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a device and method capable of electrolytically coupling synchronous denitrification and dephosphorization. Background Art

[0002] Nitrogen and phosphorus are the main causes of eutrophication of water bodies, and their removal is of great significance for controlling water pollution. In terms of denitrification, biological denitrification is mostly used, which has the advantages of low cost, environmental protection and safety. However, with the extensive use of detergents, fertilizers, etc., the N and P contents in sewage have increased significantly, the C:N:P ratio is unbalanced, the carbon source is insufficient, and the nutritional requirements of microorganisms cannot be met, resulting in a decrease in the biological denitrification effect and difficulty in meeting the effluent standards. Natural biomass fillers are generally used to solve the problem of nutrient element imbalance. Natural biomass itself has a suitable C:N:P ratio, which is degraded by microorganisms and utilized by microorganisms, thereby improving the denitrification effect. However, general herbaceous biomass such as corn cobs and straw has problems such as unstable denitrification, low denitrification efficiency, and complex operation and maintenance management. Wood biomass has good structural strength and is easy to maintain and manage, which can achieve stable denitrification, but the nitrogen removal rate is generally less than 60%, and the denitrification effect needs to be improved. In terms of phosphorus removal, electrolysis is currently mostly used for phosphorus removal. Although the effect of electrolytic dephosphorization is obvious, it has problems such as large plate consumption, high energy consumption, high effluent turbidity, and color caused by residual iron.

[0003] It has become a trend to improve the effluent standard from Class A to Class IV of surface water. The total nitrogen limit of Class A (GB18918-2002) is 15 mg / L, and the total phosphorus limit is 1 (0.5 for those constructed after 2006) mg / L; the total nitrogen limit of Class IV of surface water (GB3838-2002) is 1.5 mg / L, and the total phosphorus limit is 0.3 (0.1 for lakes and reservoirs) mg / L. Obviously, Class IV of surface water is more stringent, but the existing denitrification technology is difficult to reach the standard of Class IV of surface water. In terms of phosphorus removal, electrolytic dephosphorization has many secondary problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a device and method capable of electrolytically coupling synchronous denitrification and dephosphorization, so as to overcome the deficiencies in the above-mentioned prior art.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a method for electrolytically coupled synchronous denitrification and phosphorus removal, comprising: a reactor and an electrolysis module, wherein the reactor is provided with a coupling chamber and an electrolysis chamber, and the bottom of the coupling chamber has a hole for connecting the coupling chamber and the electrolysis chamber; the electrode plate of the electrolysis module is located in the electrolysis chamber, the material of the electrode plate is iron, and the coupling chamber is filled with ecological filler.

[0006] On the basis of the above technical solution, the present invention can also be improved as follows.

[0007] Furthermore, the ecological filler includes: a biomass filler and a natural filter material arranged above the biomass filler, wherein granular modified charcoal is distributed in the biomass filler; the natural filter material is lower than the water outlet on the coupling chamber.

[0008] Furthermore, the mass ratio of the biomass filler to the modified charcoal is 100:(5-25), and the thickness of the natural filter material is 2 cm to 10 cm.

[0009] Furthermore, the biomass used for the biomass filler is woody biomass, which is one or a combination of bamboo and rotten wood; the thickness of the fillers of different shapes processed from bamboo is 1.5mm to 25mm; the thickness of the fillers of different shapes processed from rotten wood is 15mm to 150mm.

[0010] Furthermore, the natural filter material is one or more of volcanic rock, ceramsite, and zeolite.

[0011] Furthermore, the modified charcoal is prepared by modifying charcoal with a modifier, the charcoal is prepared at a high temperature of 800°C to 1200°C, the modifier is composed of potassium dihydrogen sulfate, protease, cellulase and water, the mass ratio of the modifier to the charcoal is (5-15):100, and the mass ratio of potassium dihydrogen sulfate, protease, cellulase and water in the modifier is (0.1-3):(1-8):(3-15):100; the modification process is: evenly spray the modifier while turning the charcoal, and let it stand naturally for 24 hours.

[0012] Furthermore, the aspect ratio of the coupling chamber is 2.5 to 4.0.

[0013] Furthermore, the electrolysis module includes: electrode plates, power supply equipment and PLC system. The electrode plates are located in the electrolysis chamber, the electrode plate spacing is 10mm to 45mm, and the electrode plate thickness is 3mm to 5mm; the power supply equipment supplies power to the electrode plates and provides a DC voltage of 3V to 25V so that the electrode plates can electrolyze iron ions; the PLC system is electrically connected to the power supply equipment and controls the power supply voltage, electrolysis time and positive and negative pole switching of the power supply equipment according to the total phosphorus content and water volume of the influent.

[0014] Furthermore, the positive and negative pole switching cycle is 0.5h to 24h.

[0015] Based on the above technical solution, the present invention also provides an electrolytically coupled synchronous denitrification and dephosphorization method, which uses an electrolytically coupled synchronous denitrification and dephosphorization device, including the following steps:

[0016] S1, nitrogen and phosphorus wastewater is introduced into the electrolysis chamber;

[0017] S2. Determine the power supply voltage, electrolysis time, and positive and negative electrode switching cycle based on the total phosphorus content and water volume of the influent;

[0018] S3, the electrode plate is energized, releasing Fe2+ , Fe 2+ Reacts with oxygen in water to form Fe 3+ or iron hydroxide, iron ions and iron hydroxides quickly combine with most of the phosphorus substances in the influent water to form insoluble chemicals that precipitate at the bottom of the electrolysis chamber;

[0019] S4. The residual iron ions and iron hydroxides enter the coupling chamber and form a coupling system with the ecological filler to intercept the residual iron ions and iron hydroxides, and the residual iron ions and iron hydroxides trigger the iron coupling effect, promote the growth of denitrification and phosphorus removal functional bacteria in the filler to enhance the formation of biofilm.

[0020] The beneficial effects of the present invention are:

[0021] Nitrate-rich nitrogen and phosphorus wastewater is introduced into the electrolysis chamber, and the electrode plates are energized to release Fe 2+ , Fe 2+ Reacts with oxygen in water to form Fe 3+ Or iron hydroxide, iron ions and iron hydroxide quickly combine with most of the phosphorus substances in the influent to form insoluble chemical substances and precipitate at the bottom of the electrolysis chamber, while the remaining iron ions and iron hydroxide enter the coupling chamber through the holes at the bottom of the coupling chamber with the mixed liquid and form a coupling system with the ecological filler;

[0022] Electrolysis is coupled with ecological fillers. When the mixed liquid after electrolysis flows through the ecological fillers, on the one hand, the coupling effect caused by residual iron ions and iron hydroxides is utilized to improve the denitrification effect of the fillers, while inducing the growth of phosphorus removal microorganisms to increase the biological phosphorus removal effect and strengthen the formation of biofilms. Ultimately, the denitrification effect is improved while further purifying the residual phosphorus substances in the water, achieving an overall low-carbon and high-efficiency synchronous denitrification and phosphorus removal effect. The total nitrogen removal rate can reach 96%, and the total phosphorus removal rate can reach 98%. The total nitrogen and total phosphorus concentrations in the effluent can reach Class IV of the surface water (GB3838-2002) without too many secondary problems, achieving the purpose of synergistic efficiency in pollution reduction and carbon reduction. On the other hand, the filtration and interception effect of the ecological fillers is utilized to prolong the reaction process, effectively achieve secondary removal of phosphorus, and reduce the turbidity and chromaticity of the effluent.

[0023] In addition, by switching between positive and negative poles, the plate consumption can be reduced, the plate life can be extended, and thus the plate passivation problem can be alleviated. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural diagram of the electrolytically coupled synchronous denitrification and dephosphorization device in the present invention.

[0025] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0026] 1. Reactor, 110. Coupling chamber, 120. Electrolysis chamber, 130. Discharge port, 2. Electrolysis module, 210. Electrode plate, 220. Power supply equipment, 230. PLC system, 3. Ecological filler, 310. Biomass filler, 320. Natural filter material, 330. Modified charcoal. DETAILED DESCRIPTION

[0027] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0028] Example 1

[0029] like Figure 1 As shown, an electrolytically coupled synchronous denitrification and dephosphorization device comprises: a reactor 1 and an electrolysis module 2. The reactor 1 has a coupling chamber 110 and an electrolysis chamber 120. The bottom of the coupling chamber 110 has a hole for conducting the coupling chamber 110 and the electrolysis chamber 120.

[0030] The electrode plate 210 of the electrolysis module 2 is located in the electrolysis chamber 120 . The electrode plate 210 is made of iron. The coupling chamber 110 is filled with an ecological filler 3 .

[0031] Nitrate-rich nitrogen and phosphorus wastewater is introduced into the electrolysis chamber 120, and the electrode plate 210 is energized to release Fe 2+ , Fe 2+ Reacts with oxygen in water to form Fe 3+ or iron hydroxide, iron ions and iron hydroxide quickly combine with most of the phosphorus substances in the influent to form insoluble chemical substances and precipitate at the bottom of the electrolysis chamber 120, while the remaining iron ions and iron hydroxide enter the coupling chamber 110 through the holes at the bottom of the coupling chamber 110 with the mixed liquid and form a coupling system with the ecological filler 3;

[0032] By coupling electrolysis with ecological fillers, when the mixed liquid after electrolysis flows through the ecological fillers, on the one hand, the coupling effect caused by residual iron ions and iron hydroxides is utilized to improve the denitrification effect of the filler, while inducing the growth of phosphorus removal microorganisms to increase the biological phosphorus removal effect and strengthen the formation of biofilm, thereby ultimately improving the denitrification effect and further purifying the residual phosphorus substances in the water, and achieving an overall low-carbon and high-efficiency synchronous denitrification and phosphorus removal effect, achieving the purpose of synergistic efficiency in pollution reduction and carbon reduction, and reducing plate consumption and extending plate life; on the other hand, the filtering and interception effect of the ecological filler is utilized to extend the reaction process, achieve secondary removal of phosphorus, and reduce the turbidity and color of the effluent.

[0033] Example 2

[0034] like Figure 1 As shown, this embodiment is a further improvement on the basis of embodiment 1, specifically as follows:

[0035] The ecological filler 3 includes: a biomass filler 310 and a natural filter material 320 arranged above the biomass filler 310. Modified charcoal 330 particles are distributed in the biomass filler 310. The modified charcoal 330 provides abundant attachment and growth pores for microorganisms, induces the formation of biofilm, and promotes the aggregation and growth of functional microorganisms. The natural filter material 320 is lower than the water outlet on the coupling chamber 110, that is, the coupling chamber 110 adopts a bottom-inlet and top-outlet water outlet method. The natural filter material 320 is mainly used for surface fixation and filtration and interception of the biomass filler 310 to prevent the filler from shifting and reduce suspended matter in the outlet water.

[0036] Furthermore, the mass ratio of the biomass filler 310 to the modified charcoal 330 is 100:(5-25), and the thickness of the natural filter material 320 is 2 cm to 10 cm.

[0037] In this embodiment: the biomass used in the biomass filler 310 is wood biomass, and the wood biomass is one or a combination of bamboo and rotten wood; the fillers of different shapes processed from bamboo have a thickness of 1.5mm to 25mm, and the shapes can be filamentous, block-shaped, strip-shaped, etc.; the fillers of different shapes processed from rotten wood have a thickness of 15mm to 150mm, and the shapes can be granular, block-shaped, etc.

[0038] The reasons for choosing bamboo and decayed wood as wood biomass are as follows:

[0039] Bamboo and rotten wood have good mechanical and physical properties, are widely available, are rich in cellulose, are easy to maintain and manage, can meet the nutritional needs of denitrification and phosphorus removal microorganisms, and ensure the effectiveness of biological denitrification and phosphorus removal.

[0040] The natural filter material 320 is preferably one or more of volcanic rock, ceramsite, and zeolite. Of course, other materials are not excluded. The selection principle is that the specific gravity is higher than that of water.

[0041] Example 3

[0042] like Figure 1 As shown, this embodiment is a further improvement on the basis of embodiment 2, specifically as follows:

[0043] Modified charcoal 330 is made by modifying charcoal with a modifier;

[0044] Charcoal is prepared at a high temperature of 800℃ to 1200℃;

[0045] The modifier consists of potassium dihydrogen sulfate, protease, cellulase and water, and the mass ratio of the modifier to the charcoal is (5-15):100, wherein the mass ratio of potassium dihydrogen sulfate, protease, cellulase and water is (0.1-3):(1-8):(3-15):100;

[0046] The process of modifying charcoal is: evenly spray the modifier while turning the charcoal, and let it stand naturally for 24 hours.

[0047] Example 4

[0048] like Figure 1 As shown, this embodiment is a further improvement on the basis of any one of the embodiments 1 to 3, and the details are as follows:

[0049] The aspect ratio of the coupling chamber 110 is preferably 2.5 to 4.0. Since the water flows through the packing from bottom to top, the height cannot be too small. It is necessary to ensure that the microorganisms have sufficient contact time with the pollutants, and that the residual iron in the electrolytic dephosphorization has sufficient time to be retained in the packing to reduce the color and turbidity caused by the iron in the effluent. At the same time, if the height is too large, it will be difficult to install and construct, so the aspect ratio in this range is selected.

[0050] Example 5

[0051] like Figure 1 As shown, this embodiment is a further improvement on the basis of any one of the embodiments 1 to 4, specifically as follows:

[0052] The electrolysis module 2 includes: an electrode plate 210, a power supply device 220 and a PLC system 230. The electrode plate 210 is located in the electrolysis chamber 120. The spacing between the electrode plates 210 is 10 mm to 45 mm. The thickness of the electrode plates 210 is 3 mm to 5 mm. The shape of the electrode plates 210 is preferably rectangular. The power supply device 220 supplies power to the electrode plates 210 and provides a DC voltage of 3 to 25 V to enable the electrode plates 210 to electrolyze iron ions. The PLC system 230 is electrically connected to the power supply device 220 and controls the power supply voltage, electrolysis time, and positive and negative pole switching of the power supply device 220 according to the total phosphorus content and water volume of the influent.

[0053] The switching of positive and negative poles is mainly to alleviate electrode passivation. Normally, the switching cycle of positive and negative poles is 0.5h to 24h.

[0054] In each of the above embodiments, a discharge port 130 is provided at the bottom of the electrolysis chamber 120 , and can be used to discharge sludge when there is sludge in the electrolysis chamber 120 . Generally, the discharge port 130 is in a closed state.

[0055] Example 6

[0056] A method for electrolytically coupled synchronous denitrification and dephosphorization, using an electrolytically coupled synchronous denitrification and dephosphorization device, comprises the following steps:

[0057] S1, nitrogen and phosphorus wastewater is introduced into the electrolysis chamber 120;

[0058] S2. Determine the power supply voltage, electrolysis time, and positive and negative electrode switching cycle based on the total phosphorus content and water volume of the influent;

[0059] S3, the electrode plate 210 is energized, releasing Fe 2+ , Fe 2+ Reacts with oxygen in water to form Fe 3+ or iron hydroxide, the iron ions and iron hydroxide quickly combine with most of the phosphorus species in the influent water to form insoluble chemicals that precipitate at the bottom of the electrolysis chamber 120;

[0060] S4. The residual iron ions and iron hydroxides enter the coupling chamber 110 and form a coupling system with the ecological filler 3 to intercept the residual iron ions and iron hydroxides, and the residual iron ions and iron hydroxides trigger the iron coupling effect, promote the growth of denitrification and phosphorus removal functional bacteria in the filler to enhance the formation of biofilm.

[0061] Experimental example

[0062] Experiments were conducted on the electrolytically coupled synchronous denitrification and phosphorus removal device with the above structure. Ecological filler 3 was arranged in the coupling chamber 110. Two electrode plates 210 were 180 mm × 90 mm in size, with a plate spacing of 10 mm to 45 mm and a plate thickness of 4 mm. The voltage was 3 V to 25 V, and the positive and negative electrode exchange cycle was 0.5 to 24 h. The height-to-width ratio of the coupling chamber 110 was 2.5 to 4.0. The biomass filler 310 was bamboo shavings, and the natural filter material 320 was volcanic rock. The mass ratio of bamboo shavings to modified charcoal was 100:(5 to 25), and the thickness of the natural filter material 320 was 2 to 10 cm. The mass ratio of the modifier used for modified charcoal to charcoal was (3 to 10):100. The mass ratio of potassium dihydrogen sulfate, protease, cellulase, and water in the modifier was (0.1 to 3):(1 to 8):(3 to 15):100. The influent was nitrogen and phosphorus wastewater after septic tank and aerobic treatment.

[0063] Comparative Example 1

[0064] As a control, no ecological filler 3 is placed in the coupling chamber 110, and only electrolysis is performed. The two electrode plates 210 are 180mm×90mm in size, the plate spacing is 10mm~45mm, the plate thickness is 4mm, the voltage is 3V~25V, the positive and negative electrode exchange cycle is 0.5~24h, and the influent is nitrogen and phosphorus wastewater after septic tank and aerobic treatment.

[0065] Comparative Example 2

[0066] As a control, an ecological filler 3 is placed in the coupling chamber 110, but no electrolysis module is placed in the electrolysis chamber (120), the height-to-width ratio of the coupling chamber 110 is 2.5-4.0, the biomass filler 310 is bamboo shavings, the natural filter material 320 is volcanic rock, the mass ratio of bamboo shavings to modified charcoal is 100:(5-25), and the thickness of the natural filter material 320 is 2-10 cm; the mass ratio of the modifier used for modifying the charcoal to the charcoal is (3-10):100, the mass ratio of potassium dihydrogen sulfate, protease, cellulase and water in the modifier is (0.1-3):(1-8):(3-15):100, and the influent is nitrogen and phosphorus wastewater after septic tank and aerobic treatment.

[0067] The experimental period is 3-5 months. Based on the long-term stable average data, the experimental comparison results are shown in Table 1:

[0068] Table 1

[0069]

[0070]

[0071] As can be seen from Table 1, the nitrogen removal in control group 1 was very low. Although phosphorus could be significantly removed, the effluent phosphorus was still higher than that of surface water Class IV. In addition, the effluent turbidity and color were high, and there was a certain amount of iron waste.

[0072] Control group 2 had a certain effect on nitrogen removal, but the removal rate was not high, the total nitrogen in the effluent was still higher than that of level A, and the removal of phosphorus was less;

[0073] In experimental group 1, electrolysis coupling was adopted, and the nitrogen and phosphorus in the effluent could reach Class IV surface water (GB3838-2002). The turbidity and chromaticity of the effluent were greatly reduced, and the iron consumption was reduced, which greatly extended the life of the plate. At the same time, the present invention alleviated the plate passivation problem through positive and negative electrode conversion, improved the stability of the treatment effect, and had little secondary impact on the environment.

[0074] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An electrolytically coupled synchronous denitrification and dephosphorization device, characterized in that: include: A reactor (1) and an electrolysis module (2), wherein the reactor (1) comprises a coupling chamber (110) and an electrolysis chamber (120), and the bottom of the coupling chamber (110) comprises a hole for conducting the coupling chamber (110) and the electrolysis chamber (120); an electrode plate (210) of the electrolysis module (2) is located in the electrolysis chamber (120), and the electrode plate (210) is made of iron; and the coupling chamber (110) is filled with an ecological filler (3); The ecological filler (3) comprises: a biomass filler (310) and a natural filter material (320) arranged above the biomass filler (310), wherein granular modified charcoal (330) is distributed in the biomass filler (310); the natural filter material (320) is lower than the water outlet on the coupling chamber (110); The biomass used in the biomass filler (310) is woody biomass, which is one or a combination of bamboo and rotten wood; The modified charcoal (330) is prepared by modifying charcoal with a modifier, wherein the charcoal is prepared at a high temperature of 800°C to 1200°C, the modifier is composed of potassium dihydrogen sulfate, protease, cellulase and water, the mass ratio of the modifier to the charcoal is (5-15):100, and the mass ratio of potassium dihydrogen sulfate, protease, cellulase and water in the modifier is (0.1-3):(1-8):(3-15):100; the modification process is: evenly spray the modifier while turning the charcoal, and let it stand naturally for 24 hours.

2. The electrolytically coupled synchronous denitrification and dephosphorization device according to claim 1, characterized in that: The mass ratio of the biomass filler (310) to the modified charcoal (330) is 100:(5-25), and the thickness of the natural filter material (320) is 2 cm to 10 cm.

3. The electrolytically coupled synchronous denitrification and dephosphorization device according to claim 1, characterized in that: The thickness of the fillers processed from bamboo in different shapes ranges from 1.5 mm to 25 mm; the thickness of the fillers processed from rotten wood in different shapes ranges from 15 mm to 150 mm.

4. The electrolytically coupled synchronous denitrification and dephosphorization device according to claim 1, characterized in that: The natural filter material (320) is one or more of volcanic rock, ceramsite, and zeolite.

5. The electrolytically coupled synchronous denitrification and dephosphorization device according to any one of claims 1 to 4, characterized in that: The coupling chamber (110) has a height-to-width ratio of 2.5 to 4.

0.

6. The electrolytically coupled synchronous denitrification and dephosphorization device according to claim 1, characterized in that: The electrolysis module (2) comprises: an electrode plate (210), a power supply device (220) and a PLC system (230), wherein the electrode plate (210) is located in the electrolysis chamber (120), the spacing between the electrode plates (210) is 10 mm to 45 mm, and the thickness of the electrode plates (210) is 3 mm to 5 mm; the power supply device (220) supplies power to the electrode plates (210) and provides a 3V to 25V DC voltage so that the electrode plates (210) can electrolyze iron ions; the PLC system (230) is electrically connected to the power supply device (220) and controls the power supply voltage, electrolysis time, and positive and negative pole switching of the power supply device (220) according to the total phosphorus content and water volume of the influent water.

7. The electrolytically coupled synchronous denitrification and dephosphorization device according to claim 6, characterized in that: The positive and negative pole switching period is 0.5h to 24h.

8. A method for electrolytically coupled simultaneous denitrification and dephosphorization, characterized in that: The electrolytically coupled synchronous denitrification and dephosphorization device according to any one of claims 1 to 7 comprises the following steps: S1, nitrogen and phosphorus wastewater is introduced into the electrolysis chamber (120); S2. Determine the power supply voltage, electrolysis time, and positive and negative electrode switching cycle based on the total phosphorus content and water volume of the influent; S3, the electrode plate (210) is energized, releasing Fe 2+ , Fe 2+ Reacts with oxygen in water to form Fe 3+ or iron hydroxide, iron ions and iron hydroxide rapidly combine with most of the phosphorus species in the influent to form insoluble chemical substances that precipitate at the bottom of the electrolysis chamber (120); S4, the residual iron ions and iron hydroxides enter the coupling chamber (110) and form a coupling system with the ecological filler (3) to intercept the residual iron ions and iron hydroxides, and the residual iron ions and iron hydroxides trigger the iron coupling effect, promote the growth of denitrification and dephosphorization functional bacteria in the filler to enhance the formation of biofilm.

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