Simultaneous denitrification and phosphorus removal slow-release filler and preparation method thereof

Abstract

The present application belongs to the technical field of water pollution control, and particularly relates to a kind of simultaneous denitrification and phosphorus removal slow-release filler and a preparation method thereof.The slow-release filler is used in water purification process, and can be used as a carrier for microbial attachment and growth, and can provide various electron donors for microbial denitrification and nitrogen removal; at the same time, the water treatment process also has a significant control of release of metal phosphorus removal agent and other phosphorus removal active components, to achieve the function of enhanced phosphorus removal; and when the water quality is purified by using the slow-release filler, no harmful ingredients are introduced into the water, and the possibility of secondary pollution is significantly reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water pollution control, and particularly relates to a simultaneous denitrification and phosphorus removal slow-release filler and a preparation method thereof. BACKGROUND

[0002] Excessive nitrogen and phosphorus in water bodies will lead to problems such as eutrophication, and denitrification and phosphorus removal become one of the important tasks faced by wastewater treatment and environmental pollution control. Although traditional biological denitrification technology is widely used, it requires a certain amount of organic carbon source in the denitrification process. For low carbon-nitrogen ratio (COD / TN, i.e. C:N < 5:1) water bodies, due to the limitation of carbon source, the electron donor required for denitrification is insufficient, and complete denitrification cannot be achieved, so the traditional biological treatment technology often fails to achieve the ideal denitrification effect. In order to solve the problem of insufficient carbon source, it is usually necessary to add external organic carbon source or provide inorganic electron donor. The heterotrophic denitrification process with external carbon source will produce alkalinity, and the sludge amount is large, which increases the difficulty of subsequent treatment. Moreover, the amount of carbon source is not easy to control, which may cause insufficient or excessive carbon source. The inorganic electron donors currently used more include low-valence sulfur compounds, elemental iron and ferrous iron, hydrogen, etc. Among them, elemental sulfur is a relatively common inorganic electron donor due to its non-toxicity, easy transportation, high denitrification efficiency and other characteristics. Sulfur autotrophic denitrification will produce a large amount of H + , which reduces the pH of the reaction system, leading to reduced microbial activity, and a large amount of SO4 2- is produced.

[0003] In terms of phosphorus removal, although biological methods can remove part of the phosphorus, due to the limitation of sludge age, the improvement of phosphorus removal efficiency is limited. In order to achieve deep phosphorus removal, chemical phosphorus removal is often required after biological treatment. Phosphorus removal agents are usually continuously added by metering equipment. This not only increases the complexity of process equipment and operation, but also increases the cost. By adding slow-release phosphorus removal agents, the frequency of agent addition can be reduced. For this reason, some research institutions at home and abroad have begun to develop slow-release phosphorus removal agents.

[0004] For example, Chinese patent CN 107082479 A wraps the iron-based flocculant with an organic layer having a slow-release function, which is formed by mixing carboxymethyl chitosan with polyvinylpyrrolidone, polyacrylic acid, polyethylene oxide or polyacrylamide and other soluble polymer materials. When the iron-based phosphorus removal flocculant with slow-release function is put into water, the organic layer wrapped outside the iron-based phosphorus removal flocculant will also gradually dissolve with the reaction, so that the iron-based flocculant is released through the pores of the organic layer until the organic layer is completely dissolved. However, ① the organic components of the organic layer, i.e. the high molecular components, dissolved in water will also increase the suspended solids, precipitates and other organic components in water, causing secondary pollution. ② It is difficult to control the release rate of the slow-release phosphorus removal agent and the balance of phosphorus load in water, which may lead to waste of phosphorus removal agent and substandard phosphorus removal effect of effluent. ③ At the same time, the prepared iron-based flocculant can only achieve phosphorus removal effect and cannot simultaneously achieve denitrification effect.

[0005] Chinese patent CN 111977764 A discloses a composite phosphorus removal agent for water treatment, which is composed of 50-80 parts of phosphorus removal coagulant, 5-15 parts of hydroxypropyl methyl cellulose ether, 3-6 parts of aluminum potassium sulfate coated with ammonium molybdate, and 40-50 parts of tablet-making agent. The phosphorus removal agent uses hydroxypropyl methyl cellulose ether (HPMC) to form the outermost gel layer, which gradually dissolves during the reaction. ① The components of the hydroxypropyl methyl cellulose ether (HPMC) gel layer dissolved in water will also increase the suspended solids, precipitates and other organic components in water, causing secondary pollution. ② The obtained composite phosphorus removal agent can only be used for phosphorus removal and cannot achieve denitrification effect.

[0006] Biofilm technology is a high-efficiency biological treatment technology developed by using microorganisms to attach and grow on carriers. Generally, the biofilm carrier uses inert organic or inorganic carriers. For the problem of deep denitrification and phosphorus removal of wastewater, can we use biofilm carriers with active components to provide space for microorganisms to attach and grow, and provide electrons for microorganisms to strengthen the denitrification process under low C / N ratio, and also can strengthen the removal of phosphorus through the slow release of phosphorus active components.

[0007] Based on the problems and deficiencies in the prior art, it is urgent to provide a slow-release filler that ① has good slow-release effect; ② can be used as a microbial attachment and growth carrier; ③ can simultaneously achieve denitrification and phosphorus removal; and ④ will not cause secondary pollution due to decomposition of the outer material during the treatment process. SUMMARY

[0008] In order to overcome the above technical problems, the present application provides a simultaneous denitrification and phosphorus removal slow-release filler and a preparation method thereof, which is used for water purification, and can be used as a carrier for the attachment and growth of microorganisms and can provide various electron donors for microbial denitrification denitrification; at the same time, it also has the function of controlling the release of phosphorus removal active components to strengthen phosphorus removal; and the use of the slow-release filler for water purification does not introduce a large amount of organic components and inorganic components into the water, causing secondary pollution.

[0009] The present application provides a simultaneous denitrification and phosphorus removal slow-release filler, which is composed of an outer permeable layer wrapping an inner core slow-release layer.

[0010] The inner core slow-release layer is composed of 10-40 parts of phosphorus removal active components, 20-50 parts of paraffin, and 20-50 parts of sulfur powder.

[0011] In some preferred embodiments, the mass ratio of the three is phosphorus removal active components: paraffin: sulfur powder = 2:3:3.

[0012] The outer permeable layer is composed of 20-50 parts of sulfur powder, 20-50 parts of paraffin, and 15-35 parts of inorganic dispersant.

[0013] In some preferred embodiments, the mass ratio of the three is sulfur powder: paraffin: inorganic dispersant = 4:2.5:2.

[0014] The slow-release filler selects paraffin and sulfur as carriers, and the phosphorus removal active components are wrapped in the inner core slow-release layer through the outer permeable layer in the double-layer structure; the efficiency of the carrier in the controlled release of the phosphorus removal active components is utilized to achieve the goal of continuous phosphorus removal.

[0015] At the same time, the sulfur powder acts as an inorganic electron donor, and paraffin is used as a slow-release carbon source to provide an electron donor for microbial denitrification, thereby strengthening denitrification and realizing the synergistic performance of sulfur autotrophic denitrification and heterotrophic denitrification.

[0016] In addition, the outer permeable layer of the slow-release filler is added with an inorganic dispersant, which can not only regulate the release rate of the phosphorus removal components, but also is beneficial to the attachment and growth of microorganisms on the surface of the filler.

[0017] The phosphorus removal active components are selected from one or a combination of iron salts, magnesium salts, and aluminum salts.

[0018] The preparation process of the filler includes the following steps:

[0019] 1) The raw materials for the inner core slow-release layer are weighed according to the raw material ratio, mixed uniformly, heated and stirred to uniformly disperse the phosphorus removal active components in the molten paraffin, poured into a mold, and cooled and solidified to obtain the inner core.

[0020] 2) According to the raw material ratio of the outer permeable layer, each component raw material is weighed and mixed uniformly, and the inorganic dispersant is uniformly dispersed in the molten liquid of paraffin by heating and stirring to obtain a uniform molten liquid;

[0021] 3) The core obtained in step 1) is immersed in the molten liquid of step 2), and then taken out and condensed; the immersion and condensation process of step 3) is repeated to control the thickness of the outer permeable layer, and a slow-release filler with the performance of strengthening denitrification and phosphorus removal is obtained.

[0022] In some preferred embodiments, the core slow-release layer of the filler is a ball with a diameter of 2-3 cm, and the thickness of the outer permeable layer is 0.1-0.5 cm. The thickness of the outer permeable layer has a significant effect on the release rate of the phosphorus removal active component. More than 0.5 cm will cause the release rate to be too slow, greatly hinder the release of the phosphorus removal active component, and cause the phosphorus removal efficiency to be significantly reduced; less than 0.1 cm will cause the release rate to be too fast, and the slow-release effect cannot be achieved.

[0023] In some preferred embodiments, the phosphorus removal active component is selected from one or more of the sulfates, chlorides, and carbonates of iron, magnesium, or aluminum.

[0024] In some preferred embodiments, the inorganic dispersant is selected from one or more of activated carbon and fine sand; the particle size of the inorganic dispersant is 100-200 mesh.

[0025] In some preferred embodiments, the paraffin is sliced paraffin.

[0026] In some preferred embodiments, the heating temperature in step 1) is 70-90℃, and the stirring time is 20-30 min.

[0027] In some preferred embodiments, the heating temperature in step 2) is 65-80℃, and the stirring time is 20-30 min.

[0028] In addition, the present application also provides a slow-release filler in a water treatment process, wherein the slow-release filler is directly used in water for denitrification and / or phosphorus removal in the water treatment process.

[0029] In some preferred embodiments, the ratio of COD to total mass of TN in the water body is COD:N < 5:1.

[0030] In some preferred embodiments, the total nitrogen removal rate is 72-81%, and the total phosphorus removal rate is 88-100%.

[0031] The beneficial effects of the present application are:

[0032] The application provides a slow-release filler with the function of reinforced simultaneous denitrification and dephosphorization and a preparation method thereof. The slow-release filler uses paraffin and sulfur as carrier raw materials to provide various electron donors for microorganisms to reinforce denitrification; through double-layer structure design and coating of dephosphorization active components, the carrier has the function of controlled release of dephosphorization active components, so that the goal of continuous dephosphorization is achieved.

[0033] (1) The slow-release time of the dephosphorization active components is long, the slow-release effect is remarkable, and can be up to 200 days.

[0034] Insoluble paraffin and sulfur are used as the coating carrier of the dephosphorization active components, a double-layer structure of an outer permeation layer wrapping an inner slow-release layer is adopted, the permeability is regulated by using inorganic dispersants, the release rate of the dephosphorization active components is jointly regulated by combining the process of microbial degradation of paraffin and sulfur, the slow-release rate of the dephosphorization active components is effectively controlled, the slow-release time of the active components of the carrier is long, and can be up to 15-200 days.

[0035] (2) The raw materials of the slow-release filler can participate in water treatment reactions, and will not introduce a large amount of organic components and inorganic components to cause secondary pollution.

[0036] The main raw materials of the filler, paraffin and sulfur, are environmentally friendly, non-toxic and harmless, paraffin as a slow-release carbon source can provide carbon source and electrons for biological denitrification, and can also be biodegraded and mineralized, sulfur as an inorganic electron donor can be used by sulfur autotrophic bacteria for denitrification, the biodegradation process of paraffin and sulfur does not produce toxic and harmful by-products, compared with high molecular organic materials as coating carriers, the method is green and environmentally friendly, and there is no secondary environmental pollution.

[0037] (3) The slow-release filler has a composite function, it not only serves as a carrier for the attachment and growth of microorganisms, but also has the functions of reinforcing denitrification (the total nitrogen removal rate is as high as 81%) and dephosphorization (the total phosphorus removal rate is as high as 100%), the preparation method of the carrier is simple, the application is flexible, and the expandability is strong.

[0038] Carrier function:

[0039] The inorganic dispersant with good permeability and biological affinity added in the structure of the outer permeation layer can accelerate the attachment and growth of microorganisms on the surface of the filler in the initial stage of the reaction.

[0040] Denitrification and dephosphorization function:

[0041] ① Denitrification: sulfur powder serves as an inorganic electron donor, and paraffin is used as a slow-release carbon source to provide various electron donors for microorganisms to carry out denitrification reaction, so that denitrification is reinforced, and sulfur autotrophic denitrification and heterotrophic denitrification are cooperatively carried out, and no additional electron donor needs to be added.

[0042] Sulfur autotrophic denitrification reaction

[0043] 50NO3- +55S+20CO2+38H2O+4NH4 + →25N2+55SO4 2- +64H + +4C5H7O2N

[0044] Paraffin mediated heterotrophic denitrification reaction

[0045] C 25 H 52 +30NO3 - →25CO2+15N2+10H2O+30OH -

[0046] 2. Phosphorus removal: The present application utilizes the double-layer structure and the high-efficiency phosphorus removal active component loaded in the inner core slow-release layer, utilizes the slow dissolution of the inner and outer layers to effectively control the release speed of the phosphorus removal active component, realizes the slow-release effect, and achieves the effect of continuous phosphorus removal; at the same time, by the action of the outer permeation layer material, further phosphorus removal is realized without adding phosphorus removal active components, and the purpose of strengthening phosphorus removal is achieved.

[0047] (4) The slow-release filler of the present application simultaneously realizes the functions of denitrification and phosphorus removal, significantly reduces the generation amount of sulfate ions and sludge in the water body, ensures the balance of the acid-base degree of the water body, and further reduces the possibility of secondary pollution.

[0048] The sulfur autotrophic denitrification and paraffin mediated heterotrophic denitrification reaction cooperatively remove nitrogen, alleviate the problem of excessive generation of sulfate caused by the sulfur autotrophic denitrification reaction, effectively balance the acid-base degree of the effluent, and do not need a post-treatment process of the water body; compared with the paraffin mediated heterotrophic denitrification technology alone, the generation of residual sludge is also reduced. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is a release rate diagram of the phosphorus removal active component of the filler prepared in Example 1 and Comparative Example 1.

[0050] Figure 2 is a phosphorus removal effect diagram of the filler prepared in Example 1 in continuous operation.

[0051] Figure 3 is a denitrification effect diagram of the filler prepared in Example 1 in continuous operation. DETAILED DESCRIPTION

[0052] The specific embodiments and examples are described below. Figures 1-3The application is further illustrated in the following examples, but the scope of protection of the application is not limited to the scope of the examples. Any person skilled in the art can derive other various forms of products under the guidance of the application, but regardless of any change in shape or proportion of ingredients, any technical solution with the same or similar to the application falls within the scope of protection of the application.

[0053] Example 1

[0054] 1) According to the mass ratio of the raw materials of the core slow-release layer, sulfur powder: ferric chloride: paraffin = 30:20:30, weigh each component raw material, mix uniformly, heat to 75°C, melt the paraffin, stir for 25 min, and then pour the molten liquid into a mold to obtain the core.

[0055] 2) According to the mass ratio of the raw materials of the outer layer permeation layer, sulfur powder: paraffin: activated carbon = 40:25:20, weigh each component raw material, mix uniformly, heat to 70°C, melt the paraffin, stir for 23 min, and then pour the molten liquid into a mold to obtain the core.

[0056] 3) The core obtained in step 1) is immersed in the molten liquid obtained in step 2), and then taken out and cooled; the immersion and cooling process of step 3) is repeated to control the thickness of the outer layer permeation layer to be 0.2 cm, and the slow-release filler with enhanced denitrification and phosphorus removal performance is obtained.

[0057] Among them, the particle size of the sulfur powder taken in the above raw materials is 100 mesh, and the particle size of the activated carbon taken is 100 mesh.

[0058] The slow-release filler prepared above is used for the experiment of exploring the release rate of phosphorus removal active components, and the cumulative release rate is shown in Figure 1 The cumulative release rate is about 10% in 20 days, and the release period of the phosphorus removal components of the double-layer slow-release filler can reach 200 days.

[0059] The slow-release filler prepared above is loaded into a reactor with an inner diameter of 6 cm and a height of 100 cm, inoculated with microorganisms to explore the effect of continuous flow simultaneous denitrification and phosphorus removal, and Figure 2 is a continuous operation phosphorus removal effect diagram of the prepared filler. The removal rate of phosphate is more than 95%. The prepared influent nitrate nitrogen concentration is 20 mg / L, ammonia nitrogen is 5 mg / L, phosphorus concentration is 2 mg / L, and COD is 40 mg / L. The hydraulic retention time is 4 h, and Figure 3 is a pollutant removal effect diagram in the reactor under continuous flow operation. The total nitrogen removal rate reaches 81%, and the total phosphorus removal rate reaches 100%.

[0060] The SO4 2-The concentration is 70-90 mg / L, the pH is 7.1-7.5, the effluent is nearly neutral, the effluent COD is 10-20 mg / L, and no secondary organic pollution is caused.

[0061] Example 2

[0062] 1) According to the mass ratio of the raw materials of the core slow-release layer, sulfur powder: magnesium chloride: paraffin = 20:35:20, weigh each component raw material, mix uniformly, heat to 80℃, melt the paraffin, stir for 25 min, and then pour the molten liquid into the mold, select the spherical mold with a diameter of 2 cm, and cool and solidify to obtain the core.

[0063] 2) According to the mass ratio of the raw materials of the outer permeable layer, sulfur powder: paraffin: activated carbon = 35:20:25, weigh each component raw material, mix uniformly, heat to 70℃, melt the paraffin, stir for 23 min, and then pour the molten liquid into the mold, select the spherical mold with a diameter of 2 cm, and cool and solidify to obtain the core.

[0064] 3) The core obtained in step 1) is immersed in the molten liquid obtained in step 2), and then taken out and cooled; repeat the immersion and cooling process of step 3), control the thickness of the outer permeable layer to be 0.3 cm, and obtain the slow-release filler with enhanced denitrification and phosphorus removal performance.

[0065] Among them, the particle size of the sulfur powder taken in the above raw materials is 100 mesh, and the particle size of the activated carbon taken is 200 mesh.

[0066] The slow-release filler prepared above is used for the release rate experiment of the phosphorus removal active component, and the release period of the phosphorus removal active component of the double-layer slow-release filler can reach 180 days.

[0067] The slow-release filler prepared above is loaded into a reactor with an inner diameter of 6 cm and a height of 100 cm, inoculated with microorganisms, and the continuous flow simultaneous denitrification and phosphorus removal effect is explored. The prepared influent nitrate nitrogen concentration is 20 mg / L, ammonia nitrogen is 5 mg / L, phosphorus concentration is 3 mg / L, COD is 40 mg / L, hydraulic retention time is 4 h, total nitrogen removal rate reaches 72%, and total phosphorus removal rate reaches 88%.

[0068] The SO4 2- The concentration is 72-93 mg / L, the pH is 7.0-7.5, the effluent is nearly neutral, the effluent COD is 11-22 mg / L, and no secondary organic pollution is caused.

[0069] Example 3

[0070] 1) According to the raw material quality ratio of the core slow-release layer, sulfur powder: iron carbonate: paraffin = 35:10:40, weigh each component raw material, mix uniformly, heat to 85°C, melt the paraffin, stir for 30 min, and then pour the molten liquid into the mold. The selected spherical mold has a diameter of 3 cm, and the core is obtained after cooling and solidification.

[0071] 2) According to the raw material quality ratio of the outer layer permeation layer, sulfur powder: paraffin: fine sand = 20:40:35, weigh each component raw material, mix uniformly, heat to 80°C, melt the paraffin, stir for 20 min, and then pour the molten liquid into the mold. The selected spherical mold has a diameter of 3 cm, and the core is obtained after cooling and solidification.

[0072] 3) The core obtained in step 1) is immersed in the molten liquid obtained in step 2), and then taken out and cooled; the immersion and cooling process of step 3) is repeated to control the thickness of the outer layer permeation layer to be 0.5 cm, and the slow-release filler with enhanced denitrification and phosphorus removal performance is obtained.

[0073] Among them, the particle size of the sulfur powder taken in the above raw materials is 200 mesh, and the particle size of the activated carbon taken is 100 mesh.

[0074] The slow-release filler prepared above is used for phosphorus removal active component release rate experiment, and the phosphorus removal active component release period of the double-layer slow-release filler can reach 190 days.

[0075] The slow-release filler prepared above is loaded into a reactor with an inner diameter of 6 cm and a height of 100 cm, and inoculated with microorganisms to explore the continuous flow simultaneous denitrification and phosphorus removal effect. The prepared influent nitrate nitrogen concentration is 30 mg / L, ammonia nitrogen 5 mg / L, phosphorus concentration 2 mg / L, COD 60 mg / L, and hydraulic retention time 4 h. The total nitrogen removal rate reaches 77%, and the total phosphorus removal rate reaches 94%.

[0076] The reactor effluent SO4 2- concentration is 68-91 mg / L, pH is 6.9-7.6, maintaining the effluent near neutral, and effluent COD is 13-24 mg / L, which will not cause secondary organic pollution.

[0077] Example 4

[0078] 1) According to the raw material quality ratio of the core slow-release layer, sulfur powder: aluminum sulfate: paraffin = 50:40:50, weigh each component raw material, mix uniformly, heat to 70°C, melt the paraffin, stir for 26 min, and then pour the molten liquid into the mold. The selected spherical mold has a diameter of 2.6 cm, and the core is obtained after cooling and solidification.

[0079] 2) According to the raw material mass ratio of the outer layer permeable layer, sulfur powder: paraffin: fine sand = 50:50:15, each component raw material is taken, mixed uniformly, heated to 65℃, the paraffin is melted, stirred for 20 min, the inorganic dispersant is uniformly dispersed in the molten liquid, and a uniform molten liquid is obtained.

[0080] 3) The core obtained in step 1) is immersed in the molten liquid of step 2), and then taken out and condensed; the immersion and condensation process of step 3) is repeated, and the thickness of the outer layer permeable layer is controlled to be 0.4 cm, to obtain a slow-release filler with strong denitrification and phosphorus removal performance.

[0081] Among them, the particle size of the sulfur powder taken in the above raw materials is 100 mesh, and the particle size of the activated carbon taken is 100 mesh.

[0082] The slow-release filler prepared above is used for phosphorus removal active component release rate experiment, and the phosphorus removal active component release period of the double-layer slow-release filler can reach 170 days.

[0083] The slow-release filler prepared above is loaded into a reactor with an inner diameter of 6 cm and a height of 100 cm, and inoculated with microorganisms to explore the continuous flow simultaneous denitrification and phosphorus removal effect. The prepared influent nitrate nitrogen concentration is 20 mg / L, ammonia nitrogen 10 mg / L, phosphorus concentration 4 mg / L, COD 50 mg / L, hydraulic retention time 4 h, total nitrogen removal rate reaches 76%, and total phosphorus removal rate reaches 91%.

[0084] The reactor effluent SO4 2- concentration is 75-87 mg / L, pH is 7.2-7.7, maintaining the effluent near neutral, and effluent COD is 15-26 mg / L, which will not cause secondary organic pollution.

[0085] Comparative Example 1

[0086] The same core slow-release layer raw materials and preparation process as in Example 1 are used to prepare a single-layer slow-release filler. The specific method is as follows:

[0087] According to the mass ratio, sulfur powder: aluminum chloride: paraffin = 30:20:30, the raw materials are taken, mixed uniformly, heated to 75℃, stirred for 25 min, poured into a spherical mold, the selected spherical mold diameter is 2.5 cm, and the single-layer slow-release filler is obtained by cooling and solidification.

[0088] The particle size of the sulfur powder taken is 100 mesh, and the particle size of the activated carbon taken is 100 mesh.

[0089] The slow-release filler prepared above is used for phosphorus removal active component release rate experiment, and the cumulative release amount is shown in Figure 1 , and the cumulative release rate is as high as about 85% in only 15 days, which is basically completely released, and the slow-release effect is poor.

[0090] From the above comparison and Table 1 andFigure 1 It can be seen that, compared with the release of the phosphorus removal active component of the slow-release filler of Comparative Example 1 (single-layer structure) and Example 1 (double-layer structure), the time required for the complete release of the phosphorus removal active component of Comparative Example 1 (single-layer structure) is only about 15 days, while the 20-day cumulative release rate of Example 1 is about 10%, and the complete release period of the phosphorus removal active component of the double-layer slow-release filler is 200 days. The slow-release effect of Example 1 (double-layer structure) is improved by more than 185 days compared with Comparative Example 1 (single-layer structure), and the slow-release effect is significantly improved.

[0091] Table 1 Release rate of phosphorus removal active component in Example 1 and Comparative Example 1

[0092]

[0093]

[0094] Comparative Example 2

[0095] The difference between Comparative Example 2 and Example 1 is that the addition of sulfur powder is omitted.

[0096] The specific steps are as follows:

[0097] 1) According to the mass ratio of the raw materials of the core slow-release layer, FeCl3: paraffin = 20:30, weigh each component, mix uniformly, heat to 75°C, melt the paraffin, stir for 25 min, and then pour the molten liquid into the mold. The selected spherical mold has a diameter of 2.5 cm, and the core is obtained by cooling and solidification.

[0098] 2) According to the mass ratio of the raw materials of the outer permeation layer, paraffin: activated carbon = 25:20, weigh each component, mix uniformly, heat to 70°C, melt the paraffin, stir for 23 min, and then pour the molten liquid into the mold. The selected spherical mold has a diameter of 2.5 cm, and the core is obtained by cooling and solidification.

[0099] 3) The core obtained in step 1) is immersed in the molten liquid obtained in step 2), and then taken out and cooled; the immersion and cooling process of step 3) is repeated, and the thickness of the outer permeation layer is controlled to be 0.2 cm, to obtain a slow-release filler with enhanced denitrification and phosphorus removal performance.

[0100] Among them, the particle size of the sulfur powder taken in the above raw materials is 100 mesh, and the particle size of the activated carbon taken is 100 mesh.

[0101] The slow-release filler prepared above is used for the experiment of exploring the release rate of the phosphorus removal active component, and the release period of the phosphorus removal active component of the double-layer slow-release filler can reach 180 days.

[0102] The prepared slow-release filler was loaded into a reactor with an inner diameter of 6 cm and a height of 100 cm, and inoculated with microorganisms to explore the effect of continuous flow simultaneous denitrification and phosphorus removal. The prepared influent had a nitrate nitrogen concentration of 20 mg / L, an ammonia nitrogen concentration of 5 mg / L, a phosphorus concentration of 3 mg / L, and a COD of 40 mg / L. The hydraulic retention time was 4 h, the total nitrogen removal rate was 44%, and the total phosphorus removal rate was 72%.

[0103] After water treatment, the SO4 2- The concentration was 20-30 mg / L (background value when water was prepared), and the pH was 8.1-8.6. The alkalinity of the effluent increased significantly, and it was not possible to achieve a near-neutral discharge standard.

[0104] Example 1 Comparative Example 2 Difference in slow-release filler Addition of sulfur powder Omission of sulfur powder Total nitrogen removal rate / % 81 44 Total phosphorus removal rate / % 100 72 Effluent pH 7.1-7.5 8.1-8.6

[0105] By comparing Example 1 (adding sulfur powder) and Comparative Example 2 (omitting sulfur powder), it can be seen that the addition of sulfur powder can occur as inorganic electron donor sulfur autotrophic denitrification, significantly improving the total nitrogen removal rate. Compared with Comparative Example 2 (omitting sulfur powder), the total nitrogen removal rate of Example 1 (adding sulfur powder) increased by 40%; the effect was significant. At the same time, Example 1 (adding sulfur powder) can completely remove phosphorus elements in the water body, and the total phosphorus removal rate reaches 100%. In Comparative Example 2 (omitting sulfur powder), complete removal of phosphorus elements in the water body cannot be achieved, and compared with Example 1 (adding sulfur powder), the total phosphorus removal rate of Comparative Example 2 (omitting sulfur powder) decreased by 39%, and the effect was significant.

[0106] And due to the occurrence of sulfur autotrophic denitrification reaction, H + , balancing the alkalinity produced by heterotrophic denitrification, maintaining the near-neutral pH of the effluent, and reducing the operation of subsequent treatment.

[0107] Comparative Example 3

[0108] Comparative Example 3 and Example 1 differ in that the addition of paraffin wax is omitted. Since the melting point of sulfur is 112.8°C, the melting temperature during preparation is increased to 115°C.

[0109] The specific steps are as follows:

[0110] 1) According to the mass ratio of the core slow-release layer, sulfur powder: ferric chloride = 30:20, weigh each component, mix uniformly, heat to 115°C, melt the sulfur powder, stir for 25 min, and then pour the molten liquid into the mold. The selected spherical mold has a diameter of 2.5 cm, and the core is obtained after cooling and solidification.

[0111] 2) According to the mass ratio of the raw materials of the outer permeable layer, sulfur powder: activated carbon = 40:20, each component raw material is weighed, mixed uniformly, heated to 115°C, the sulfur powder is melted, stirred for 23 min, the inorganic dispersant is uniformly dispersed in the molten liquid, and a uniform molten liquid is obtained.

[0112] 3) The core obtained in step 1) is immersed in the molten liquid obtained in step 2), and then taken out and condensed; the immersion and condensation process of step 3) is repeated, and the thickness of the outer permeable layer is controlled to be 0.2 cm, to obtain a slow-release filler with enhanced denitrification and phosphorus removal performance.

[0113] Among them, the particle size of the sulfur powder taken in the above raw materials is 100 mesh, and the particle size of the activated carbon taken is 100 mesh.

[0114] The slow-release filler prepared above is used for phosphorus removal active component release rate experiment, and the phosphorus removal active component release period of the double-layer slow-release filler can reach 170 days.

[0115] The slow-release filler prepared above is loaded into a reactor with an inner diameter of 6 cm and a height of 100 cm, and inoculated with microorganisms to explore the continuous flow simultaneous denitrification and phosphorus removal effect. The prepared influent nitrate nitrogen concentration is 20 mg / L, ammonia nitrogen 5 mg / L, phosphorus concentration 3 mg / L, COD 40 mg / L, hydraulic retention time 4 h, total nitrogen removal rate 40%, and total phosphorus removal rate 77%.

[0116] After water treatment, the reactor effluent SO4 2- The concentration is 150-200 mg / L, and the pH is 5.7-6.1. The effluent pH is significantly enhanced, and it is difficult to achieve the near-neutral discharge standard, and further post-treatment process is needed, which further increases the treatment difficulty and cost.

[0117] Example 1 Comparative Example 3 Difference in slow-release filler Addition of paraffin wax Omission of paraffin wax Total nitrogen removal rate / % 81 40 Total phosphorus removal rate / % 100 77 Water SO4 2- Concentration / mg / L 70-90 150-200 Effluent pH 7.1-7.5 5.7-6.1

[0118] By comparing Example 1 (adding paraffin) and Comparative Example 3 (omitting paraffin), it can be seen that the sulfate produced by using sulfur alone as the denitrification electron donor in Comparative Example 3 (omitting paraffin) is significantly increased (increased by 60-130 mg / L) compared to Example 1 (adding paraffin), and the effluent is acidic, increasing the difficulty of subsequent treatment.

Claims

1. A simultaneous denitrification and phosphorus removal slow-release filler, characterized in that, The filler is composed of an outer permeable layer wrapping an inner core slow-release layer; The inner core slow-release layer is composed of 10-40 parts of phosphorus removal active component, 20-50 parts of paraffin wax, and 20-50 parts of sulfur powder; The outer permeable layer is composed of 20-50 parts of sulfur powder, 20-50 parts of paraffin wax, and 15-35 parts of inorganic dispersant; The phosphorus removal active component is selected from one or a combination of iron salt, magnesium salt, and aluminum salt; The preparation process of the filler comprises the following steps: 1) Weigh each component according to the raw material ratio of the inner core slow-release layer, mix uniformly, heat and stir to uniformly disperse the phosphorus removal active component in the molten paraffin wax, pour into a mold, and cool and solidify to obtain the inner core; 2) Weigh each component according to the raw material ratio of the outer permeable layer, mix uniformly, heat and stir to uniformly disperse the inorganic dispersant in the molten paraffin wax, and obtain a uniform molten liquid; 3) Immerse the inner core obtained in step 1) in the molten liquid obtained in step 2), then take it out and condense; repeat the immersion and condensation process of step 3), control the thickness of the outer permeable layer, and obtain a slow-release filler with enhanced denitrification and phosphorus removal performance.

2. The simultaneous nitrification and denitrification phosphorous removing slow release filler according to claim 1, characterized in that, The inner core slow-release layer of the filler is a sphere with a diameter of 2-3 cm, and the thickness of the outer permeable layer is 0.1-0.5 cm.

3. The simultaneous nitrification and denitrification phosphorous removing slow release filler according to claim 1, characterized in that, The phosphorus removal active component is selected from one or a combination of sulfuric acid salts, chlorides, and carbonates of iron, magnesium, or aluminum.

4. The simultaneous nitrification and denitrification phosphorous removing slow release media according to claim 1, characterized in that, The inorganic dispersant is selected from one or several of activated carbon and fine sand; the particle size of the inorganic dispersant is 100-200 mesh.

5. The simultaneous nitrification and denitrification phosphorous removing slow release media according to claim 1, characterized in that, The paraffin wax is sliced paraffin wax.

6. The simultaneous nitrification and denitrification phosphorous removing slow release media according to claim 1, characterized in that, The heating temperature in step 1) is 70-90°C, and the stirring time is 20-30 min.

7. The simultaneous nitrification and denitrification phosphorous removing slow release media according to claim 1, wherein, The heating temperature in step 2) is 65-80°C, and the stirring time is 20-30 min.

8. Use of the slow-release filler according to any one of claims 1 to 7 in a water treatment process, characterized in that, The slow-release filler is directly used for denitrification and / or phosphorus removal in low carbon-nitrogen ratio water bodies during water treatment.

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