CN115724525A - Synchronous nitrogen and phosphorus removal slow-release filler and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of water pollution control, and particularly relates to a synchronous nitrogen and phosphorus removal slow-release filler and a preparation method thereof. The slow release filler is used in the water quality purification process, can be used as a carrier for the attachment growth of microorganisms, and can also provide a plurality of electron donors for the denitrification of the microorganisms; meanwhile, in the water treatment process, the phosphorus removal active components such as a metal phosphorus removal agent and the like are obviously and controllably released, so that the function of strengthening phosphorus removal is realized; in addition, when the water quality is purified by the water purifier, no harmful components are introduced into the water, and the possibility of secondary pollution is obviously reduced.

Description

A kind of simultaneous denitrification and dephosphorization slow-release filler and preparation method thereof

technical field

The invention belongs to the technical field of water pollution control, and in particular relates to a simultaneous denitrification and dephosphorization slow-release filler and a preparation method thereof.

Background technique

Excessive nitrogen and phosphorus in water bodies will lead to eutrophication and other problems. Nitrogen and phosphorus removal has become one of the important tasks facing wastewater treatment and environmental pollution control. Although the traditional biological denitrification technology is widely used, it requires a certain amount of organic carbon source in the denitrification process. For water bodies with a low carbon-to-nitrogen ratio (COD/TN, that is, C:N<5:1), due to the limited carbon source, the electron donors required for denitrification are insufficient, and complete denitrification cannot be completed. Traditional biological treatment technologies are often difficult to achieve. Ideal denitrification effect. In order to solve the problem of insufficient carbon sources, it is usually necessary to add an organic carbon source or provide an inorganic electron donor. The process of heterotrophic denitrification and denitrification with external carbon source will produce alkalinity, and the amount of sludge is large, making subsequent treatment more difficult; and the amount of carbon source added is not easy to control, which may cause insufficient or excessive carbon source. The currently used inorganic electron donors include low-valence sulfur compounds, elemental iron and ferrous iron, and hydrogen. Among them, elemental sulfur has become a commonly used inorganic electron donor due to its non-toxicity, easy transportation, and high denitrification efficiency. Sulfur autotrophic denitrification will generate a large amount of H ⁺ , which will reduce the pH of the reaction system and lead to a decrease in microbial activity. , and produce a large amount of SO ₄ ^2- .

In terms of phosphorus removal, although biological methods can remove part of phosphorus, due to the limitation of sludge age, the improvement of phosphorus removal efficiency is limited. In order to achieve deep phosphorus removal, it is often necessary to carry out chemical phosphorus removal after biological treatment. Phosphorus removal agents are usually continuously dosed using 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 domestic and foreign research institutions have begun to develop slow-release phosphorus removal agents.

For example, Chinese patent CN 107082479 A wraps an organic layer with a slow-release function on the iron-based flocculant, and the organic layer is composed of carboxymethyl chitosan and polyvinylpyrrolidone, polyacrylic acid, polyethylene oxide or polyacrylamide, etc. It is made of a mixture of polymer materials. When the iron-based phosphorus-removing flocculant with slow-release function is put into water, the organic layer wrapped around the iron-based phosphorus-removing flocculant will gradually dissolve with the reaction, so that the iron-based flocculation The agent 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, that is, the polymer components, are dissolved in water, which will also increase the suspended solids, sediments and other organic components in the water, causing secondary pollution. ②Aiming at the change of phosphorus load in water, it is difficult to control the release rate of 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 in effluent. ③At the same time, the iron-based flocculant prepared by it can only achieve the effect of phosphorus removal, and cannot simultaneously exert the effect of nitrogen removal.

Chinese patent CN 111977764 A discloses a composite phosphorus removal agent for water treatment, which consists of 50-80 parts of phosphorus removal coagulant, 5-15 parts of hydroxypropyl methylcellulose ether, 3-6 parts of molybdenum Ammonium acid coated aluminum potassium sulfate, 40-50 tablets. The phosphorus removal agent utilizes hydroxypropyl methyl cellulose (HPMC) to form the outermost gel layer, and the hydroxypropyl methyl cellulose (HPMC) gel layer gradually dissolves during the reaction. ① Its hydroxypropyl methylcellulose ether (HPMC) gel layer component is dissolved in water, which will also increase suspended solids, sediment and other organic components in water, causing secondary pollution. ② The obtained composite phosphorus removal agent is only suitable for the removal of phosphorus, and cannot achieve the denitrification effect.

Biofilm technology is an efficient biological treatment technology developed by using microorganisms attached to grow on the carrier. Usually biofilm carrier adopts inert organic or inorganic carrier. Aiming at the problem of deep denitrification and phosphorus removal of sewage, can biofilm carriers with active components be used to increase the space for microorganisms to attach and grow, and at the same time provide electrons for microorganisms to strengthen the denitrification process at low C/N ratios? Phosphorus removal is enhanced by slow release of phosphorus removal active components.

Based on the problems and deficiencies in the above-mentioned prior art, it is urgent to provide a kind of slow-release filler that ①has a good slow-release effect; ②can be used as a microbial attachment growth carrier; ③and can simultaneously realize denitrification and phosphorus removal; ④treatment During the process, there will be no secondary pollution caused by the decomposition of the outer material.

Contents of the invention

In order to overcome the above-mentioned technical problems, the present invention provides a simultaneous denitrification and dephosphorization slow-release filler and a preparation method thereof, which are used for water purification. Nitrogen provides a variety of electron donors; at the same time, it also has the function of controlling the release of phosphorus removal active components to enhance phosphorus removal; using it for water purification will not introduce a large amount of organic and inorganic components into the water, causing secondary secondary pollution.

The invention provides a slow-release filler for simultaneous denitrification and phosphorus removal, the filler is composed of an outer permeable layer wrapped with an inner core slow-release layer;

The inner core sustained-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;

In some preferred embodiments, the mass ratio of the three is, phosphorus removal active component: paraffin: sulfur powder=2:3:3;

The outer layer of permeable layer is composed of 20-50 parts of sulfur powder, 20-50 parts of paraffin wax, and 15-35 parts of inorganic dispersant;

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

The slow-release filler selects paraffin and sulfur as the carrier, wraps the phosphorus removal active component in the inner core slow-release layer through the outer permeable layer in the double-layer structure; uses the carrier to control the performance of the phosphorus removal active component to achieve continuous target for phosphorus removal.

At the same time, sulfur powder is used as an inorganic electron donor, and paraffin wax is used as a slow-release carbon source to provide microorganisms with an electron donor for denitrification reaction, thereby strengthening denitrification, and realizing sulfur autotrophic denitrification denitrification and heterotrophic denitrification. Synergy of nitrification and denitrification reactions.

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

The phosphorus removal active component is selected from one or more combinations of iron salts, magnesium salts, and aluminum salts;

The preparation process of described filler comprises the following steps:

1) Weigh the raw materials of each component according to the raw material ratio of the inner core slow-release layer, mix evenly, heat and stir to make the phosphorus removal active component evenly dispersed in the molten paraffin, pour it into a mold, cool and solidify to obtain the inner core;

2) Weighing the raw materials of each component according to the raw material ratio of the outer layer permeable layer, mixing them uniformly, heating and stirring to make the inorganic dispersant evenly dispersed in the melt of paraffin wax, and obtain a uniform melt;

3) Immerse the inner core obtained in step 1) in the molten liquid in step 2), and then take it out to condense; repeat the immersion and condensation process in step 3), control the thickness of the outer layer of permeable layer, and obtain a buffer with enhanced denitrification and phosphorus removal performance. release filler.

In some preferred embodiments, the inner inner sustained-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 impact on the release rate of the phosphorus removal active component. Exceeding 0.5 cm will lead to a slow release rate, which greatly hinders the release of the phosphorus removal active component, resulting in a significant decrease in phosphorus removal efficiency; low The release rate is too fast at 0.1cm, and the sustained release effect cannot be realized.

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

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.

In some preferred embodiments, the paraffin is sectioned paraffin.

In some preferred embodiments, the heating temperature in the step 1) is 70-90° C., and the stirring time is 20-30 min.

In some preferred embodiments, the heating temperature in step 2) is 65-80° C., and the stirring time is 20-30 min.

In addition, the present invention also provides an application of the slow-release filler in the water treatment process, the slow-release filler is directly used in the water body for denitrification and/or phosphorus removal during the water treatment process;

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

Among them, the removal rate of total nitrogen reaches 72-81%, and the removal rate of total phosphorus reaches 88-100%.

Beneficial effects of the present invention:

The invention provides a slow-release filler with enhanced synchronous nitrogen and phosphorus removal functions and a preparation method thereof. The slow-release filler uses paraffin and sulfur as carrier materials to provide microorganisms with a variety of electron donors to enhance denitrification; through the double-layer structure design and the coating of phosphorus-removing active components, the carrier has a controlled release of phosphorus-removing active components. Sub-efficiency, to achieve the goal of continuous phosphorus removal.

(1) The dephosphorization active component has a long slow-release time, and the slow-release effect is remarkable, which can be as high as 200 days.

Insoluble paraffin and sulfur are used as the coating carrier of the phosphorus removal active component, and the double-layer structure of the inner core slow-release layer is wrapped by the outer permeable layer, and the permeability is adjusted by using an inorganic dispersant, and the phosphorus removal is jointly regulated by combining the process of microbial degradation of paraffin and sulfur The release rate of the active component can effectively control the slow release rate of the phosphorus removal active component, and the carrier can release the active component for a long time, which can reach 15-200 days.

(2) The raw material of the slow-release filler can participate in the water treatment reaction, and will not introduce a large amount of organic components and inorganic components, causing secondary pollution.

The main raw materials of the filler are paraffin wax and sulfur, which are environmentally friendly, non-toxic and harmless. Paraffin wax, 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 It is used by sulfur autotrophic bacteria for denitrification, and no toxic and harmful by-products are produced during the biodegradation process of paraffin and sulfur. Compared with polymer organic materials used as coating carriers, this method is green and environmentally friendly, and has no secondary environmental pollution.

(3) The slow-release filler of the present invention has a composite function. It is used as a carrier for microbial attachment and growth, and has the function of strengthening denitrification (total nitrogen removal rate up to 81%) and phosphorus removal (total phosphorus removal rate is up to 100%). The preparation method is simple, the application is flexible, and the expandability is strong.

Carrier function:

Adding an inorganic dispersant with good permeability and bio-affinity to the structure of the outer permeable layer can accelerate the attachment and growth of microorganisms on the surface of the filler in the initial stage of the reaction.

Nitrogen and phosphorus removal function:

①Denitrification: Sulfur powder is used as an inorganic electron donor, and paraffin wax is used as a slow-release carbon source to provide microorganisms with a variety of electron donors for denitrification reactions, thereby strengthening denitrification, and realizing sulfur autotrophic denitrification and heterotrophic denitrification. The synergistic process of denitrification and denitrification reaction does not require additional electron donors. in,

Sulfur autotrophic denitrification reaction

50NO ₃ ^- +55S+20CO ₂ +38H ₂ O+4NH ₄ ⁺ →25N ₂ +55SO ₄ ^2- +64H ⁺ +4C ₅ H ₇ O ₂ N

Paraffin-mediated heterotrophic denitrification

C ₂₅ H ₅₂ +30NO ₃ ^- → 25CO ₂ +15N ₂ +10H ₂ O+30OH ^-

② Phosphorus removal: The present invention utilizes the double-layer structure and the high-efficiency phosphorus removal active components loaded by the inner core slow-release layer, and utilizes the slow dissolution of the inner and outer layers to effectively control the release rate of the phosphorus removal active components, realize the slow-release effect, and achieve continuous removal. Phosphorus effect; at the same time, by using the function of the outer permeable layer material, through adsorption, ion exchange, complexation, etc., further phosphorus removal is not required on the basis of adding phosphorus removal active components, so as to achieve the purpose of strengthening phosphorus removal.

(4) The slow-release filler of the present invention simultaneously realizes the denitrification and phosphorus removal functions, significantly reduces the generation of sulfate ions and sludge in the water body, ensures the pH balance of the water body, and further reduces the possibility of secondary pollution.

Sulfur autotrophic denitrification and paraffin-mediated heterotrophic denitrification denitrification synergistically remove nitrogen, which alleviates the problem of excessive sulfate radical production caused by sulfur autotrophic denitrification, effectively balances the pH of the effluent, and does not require water The post-treatment process; compared with the single paraffin-mediated heterotrophic denitrification technology, it also reduces the generation of excess sludge.

Description of drawings:

Fig. 1 is a graph showing the release rate of the phosphorus removal active components of the fillers prepared in Example 1 and Comparative Example 1.

Fig. 2 is the dephosphorization effect diagram of the filler prepared in Example 1 in continuous operation.

Fig. 3 is a denitrification effect diagram of the packing prepared in Example 1 in continuous operation.

Detailed ways:

Below in conjunction with specific embodiment and Fig. 1～3, the present invention will be further described, but the scope of protection claimed by the present invention is not limited to the scope of embodiment expression, anyone can draw other various forms under the enlightenment of the present invention Products, but no matter any changes are made in its shape or composition ratio, any technical solutions that are the same as or similar to the present application all fall within the protection scope of the present invention.

Example 1

1) According to the mass ratio of the raw materials of the inner core slow-release layer, sulfur powder: ferric chloride: paraffin = 30:20:30, weigh the raw materials of each component, mix evenly, heat to 75 ° C, melt the paraffin, stir for 25 minutes, and make The phosphorus removal active component, ferric chloride, is evenly dispersed in the molten liquid, and then the molten liquid is poured into a mold, the selected spherical mold has a diameter of 2.5 cm, cooled and solidified to obtain the inner core.

2) According to the mass ratio of the raw materials of the outer permeable layer, sulfur powder: paraffin: activated carbon = 40:25:20, weigh the raw materials of each component, mix evenly, heat to 70°C to melt the paraffin, stir for 23 minutes, and evenly mix the inorganic dispersant Dispersed in the melt to obtain a uniform melt.

3) Immerse the inner core obtained in step 1) in the molten liquid of step 2), and then take out and condense; repeat the immersion and condensation process of step 3), control the thickness of the outer layer of permeable layer to be 0.2cm, and obtain a compound with enhanced denitrification and phosphorus removal performance slow-release filler.

Wherein, the particle size of the sulfur powder taken in the above raw materials is 100 mesh, and the particle size of the activated carbon is 100 mesh.

The slow-release filler prepared above was used to explore the release rate of the phosphorus removal active component. The cumulative release rate is shown in Figure 1. The 20-day cumulative release rate was about 10%. The release rate of the phosphorus removal component of the double-layer slow-release filler was The cycle can reach 200 days.

Put the slow-release filler prepared above into a reactor with an inner diameter of 6 cm and a height of 100 cm, and inoculate microorganisms to explore the effect of continuous flow synchronous denitrification and phosphorus removal. Attached figure 2 is the effect diagram of the prepared filler for continuous operation of phosphorus removal. The phosphate removal rate is 95 %above. The prepared influent nitrate nitrogen concentration is 20mg/L, ammonia nitrogen 5mg/L, phosphorus concentration 2mg/L, COD 40mg/L, and hydraulic retention time 4h. Attachment 3 shows the effect of removing pollutants during continuous flow operation in the reactor As shown in the figure, the removal rate of total nitrogen reaches 81%, and the removal rate of total phosphorus reaches 100%.

The concentration of SO ₄ ^2- in the effluent from the reactor is 70-90mg/L, the pH is 7.1-7.5, the effluent is kept near neutral, and the COD of the effluent is 10-20mg/L, which will not cause secondary organic pollution.

Example 2

1) According to the mass ratio of the raw materials of the inner core slow-release layer, sulfur powder: magnesium chloride: paraffin = 20:35:20, weigh the raw materials of each component, mix evenly, heat to 80°C to melt the paraffin, and stir for 25 minutes to remove phosphorus The active component ferric chloride is evenly dispersed in the molten liquid, and then the molten liquid is poured into a mold, the selected spherical mold has a diameter of 2 cm, cooled and solidified to obtain the inner core.

2) According to the mass ratio of the raw materials of the outer permeable layer, sulfur powder: paraffin: activated carbon = 35:20:25, weigh the raw materials of each component, mix evenly, heat to 70°C to melt the paraffin, stir for 23 minutes, and evenly mix the inorganic dispersant Dispersed in the melt to obtain a uniform melt.

3) Immerse the inner core obtained in step 1) in the molten liquid of step 2), and then take out and condense; repeat the immersion and condensation process of step 3), control the thickness of the outer layer of permeable layer to be 0.3cm, and obtain a compound with enhanced denitrification and phosphorus removal performance slow-release filler.

Wherein, the particle size of the sulfur powder taken in the above raw materials is 100 mesh, and the particle size of the activated carbon is 200 mesh.

The slow-release filler prepared above was used to explore 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.

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

The concentration of SO ₄ ^2- in the effluent from the reactor is 72-93mg/L, the pH is 7.0-7.5, the effluent is kept near neutral, and the COD of the effluent is 11-22mg/L, which will not cause secondary organic pollution.

Example 3

1) According to the mass ratio of the raw materials of the inner core slow-release layer, sulfur powder: iron carbonate: paraffin = 35:10:40, weigh the raw materials of each component, mix evenly, heat to 85°C to melt the paraffin, stir for 30 minutes, and remove The phosphorus active component, ferric chloride, is uniformly dispersed in the molten liquid, and then the molten liquid is poured into a mold, the selected spherical mold has a diameter of 3 cm, cooled and solidified to obtain the inner core.

2) According to the mass ratio of the raw materials of the outer permeable layer, sulfur powder: paraffin: fine sand = 20:40:35, weigh the raw materials of each component, mix them evenly, heat to 80°C to melt the paraffin, stir for 20 minutes, and mix the inorganic dispersant Uniformly dispersed in the melt to obtain a uniform melt.

3) Immerse the inner core obtained in step 1) in the molten liquid of step 2), and then take out and condense; repeat the immersion and condensation process of step 3), control the thickness of the outer layer of permeable layer to be 0.5cm, and obtain a compound with enhanced denitrification and phosphorus removal performance slow-release filler.

Wherein, 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.

The slow-release filler prepared above was used in the experiment to explore 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 190 days.

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

The concentration of SO ₄ ^2- in the effluent from the reactor is 68-91mg/L, the pH is 6.9-7.6 to maintain the near neutrality of the effluent, and the COD of the effluent is 13-24mg/L, which will not cause secondary organic pollution.

Example 4

1) According to the mass ratio of the raw materials of the inner core slow-release layer sulfur powder: aluminum sulfate: paraffin = 50:40:50, weigh the raw materials of each component, mix evenly, heat to 70°C to melt the paraffin, stir for 26 minutes, and remove The phosphorus active component, ferric chloride, is uniformly dispersed in the molten liquid, and then the molten liquid is poured into a mold, the diameter of the selected spherical mold is 2.6 cm, cooled and solidified to obtain the inner core.

2) According to the mass ratio of the raw materials of the outer permeable layer, sulfur powder: paraffin: fine sand = 50:50:15, weigh the raw materials of each component, mix evenly, heat to 65°C to melt the paraffin, stir for 20 minutes, and mix the inorganic dispersant Uniformly dispersed in the melt to obtain a uniform melt.

3) Immerse the inner core obtained in step 1) in the molten liquid of step 2), and then take out and condense; repeat the immersion and condensation process of step 3), control the thickness of the outer layer of permeable layer to be 0.4cm, and obtain a compound with enhanced denitrification and phosphorus removal performance slow-release filler.

Wherein, the particle size of the sulfur powder taken in the above raw materials is 100 mesh, and the particle size of the activated carbon is 100 mesh.

The slow-release filler prepared above was used to explore the release rate of the phosphorus removal active component. The release period of the double-layer slow-release filler phosphorus removal active component can reach 170 days.

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

The concentration of SO ₄ ^2- in the effluent from the reactor is 75-87mg/L, the pH is 7.2-7.7 to maintain the near neutrality of the effluent, and the COD of the effluent is 15-26mg/L, which will not cause secondary organic pollution.

Comparative example 1

Using the same inner core sustained-release layer material and preparation process as in Example 1, a single-layer sustained-release filler was prepared. The specific method is as follows:

According to the mass ratio, sulfur powder: aluminum chloride: paraffin wax = 30:20:30 Weigh the raw materials, mix evenly, heat to 75°C, stir for 25 minutes, pour into a spherical mold, the diameter of the selected spherical mold is 2.5cm, cool and solidify A single-layer slow-release filler is obtained.

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

The slow-release filler prepared above was used to explore the release rate of phosphorus removal active components. The cumulative release rate is shown in Figure 1. The cumulative release rate was as high as about 85% in only 15 days. The release was basically complete and the sustained-release effect was excellent. Difference.

From above-mentioned comparison and table 1 and Fig. 1 as can be seen, comparative example 1 (single-layer structure) and the slow-release filler of embodiment 1 (double-layer structure) are compared, and the phosphorus removal active component of the two releases completely in the required time , comparative example 1 (single-layer structure) takes only about 15 days, and the 20-day cumulative release rate is about 10% in Example 1, and the complete release period of the double-layer slow-release filler phosphorus removal active component is 200 days, implement Compared with Comparative Example 1 (single-layer structure), the sustained-release effect of Example 1 (double-layer structure) was improved for more than 185 days, and the sustained-release effect was significantly improved.

The release rate of phosphorus removal active component in table 1 embodiment 1 and comparative example 1

Comparative example 2

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

Specific steps are as follows:

1) According to the mass ratio of the raw materials of the inner core slow-release layer, ferric chloride: paraffin = 20:30, weigh the raw materials of each component, mix evenly, heat to 75°C to melt the paraffin, and stir for 25 minutes to make the phosphorus removal active group The ferric chloride is evenly dispersed in the molten liquid, and then the molten liquid is poured into a mold, the diameter of the selected spherical mold is 2.5 cm, cooled and solidified to obtain the inner core.

2) According to the mass ratio of the raw materials of the outer permeable layer, paraffin: activated carbon = 25:20, weigh the raw materials of each component, mix them evenly, heat to 70°C to melt the paraffin, stir for 23 minutes, and evenly disperse the inorganic dispersant in the molten liquid , a homogeneous melt was obtained.

3) Immerse the inner core obtained in step 1) in the molten liquid of step 2), and then take out and condense; repeat the immersion and condensation process of step 3), control the thickness of the outer layer of permeable layer to be 0.2cm, and obtain a compound with enhanced denitrification and phosphorus removal performance slow-release filler.

Wherein, the particle size of the sulfur powder taken in the above raw materials is 100 mesh, and the particle size of the activated carbon is 100 mesh.

The slow-release filler prepared above was used to explore the release rate of the phosphorus removal active component. The release cycle of the double-layer slow-release filler phosphorus removal active component can reach 180 days.

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

After the water treatment is completed, the concentration of SO ₄ ^2- in the effluent from the reactor is 20-30 mg/L (the background value during water distribution), and the pH is 8.1-8.6. The alkalinity of the effluent water quality has increased significantly, and the near-neutral discharge standard cannot be achieved.

Example 1 Comparative example 2 The difference between slow-release fillers add sulfur powder omit sulfur powder Total nitrogen removal rate/% 81 44 Total phosphorus removal rate/% 100 72 Effluent pH 7.1-7.5 8.1-8.6

Combining the comparison of Example 1 (adding sulfur powder) and Comparative Example 2 (omitting sulfur powder), it can be seen that the addition of sulfur powder can be used as an inorganic electron donor for sulfur autotrophic denitrification and significantly improve the removal rate of total nitrogen. Compared with Comparative Example 2 (omitting sulfur powder) in Example 1 (adding sulfur powder), the total nitrogen removal rate is increased by 40%; the improvement effect is remarkable. Meanwhile, embodiment 1 (adding sulfur powder) can remove the phosphorus element in the water body completely, and total phosphorus removal rate reaches 100%, can't realize the complete removal of the phosphorus element in the water body in comparative example 2 (omit sulfur powder), and Compared with Example 1 (adding sulfur powder), the total phosphorus removal rate of Comparative Example 2 (omitting sulfur powder) was reduced by 39%, and the reduction effect was remarkable.

Moreover, due to the occurrence of sulfur autotrophic denitrification reaction, H ⁺ is generated to balance the alkalinity generated by heterotrophic denitrification, maintain the near-neutral pH of the effluent, and reduce the subsequent treatment operations.

Comparative example 3

The difference between Comparative Example 3 and Example 1 is that the addition of paraffin is omitted, and since the melting point of sulfur is 112.8°C, the melting temperature increases to 115°C during the preparation process.

Specific steps are as follows:

1) According to the mass ratio of the raw materials of the inner core slow-release layer, sulfur powder: ferric chloride = 30:20, weigh the raw materials of each component, mix evenly, heat to 115°C to melt the sulfur powder, and stir for 25 minutes to remove phosphorus The active component ferric chloride is evenly dispersed in the molten liquid, and then the molten liquid is poured into a mold, the selected spherical mold has a diameter of 2.5 cm, cooled and solidified to obtain the inner core.

2) According to the mass ratio of the raw materials of the outer permeable layer, sulfur powder: activated carbon = 40:20, weigh the raw materials of each component, mix evenly, heat to 115°C to melt the sulfur powder, stir for 23 minutes, and evenly disperse the inorganic dispersant in the In the melt, a uniform melt was obtained.

3) Immerse the inner core obtained in step 1) in the molten liquid of step 2), and then take out and condense; repeat the immersion and condensation process of step 3), control the thickness of the outer layer of permeable layer to be 0.2cm, and obtain a compound with enhanced denitrification and phosphorus removal performance slow-release filler.

Wherein, the particle size of the sulfur powder taken in the above raw materials is 100 mesh, and the particle size of the activated carbon is 100 mesh.

The slow-release filler prepared above was used to explore the release rate of the phosphorus removal active component. The release period of the double-layer slow-release filler phosphorus removal active component can reach 170 days.

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

After the water treatment is completed, the concentration of SO ₄ ^2- in the effluent from the reactor is 150-200 mg/L, and the pH is 5.7-6.1. The acidity of the pH of the effluent is significantly enhanced, and the near-neutral discharge standard cannot be achieved, and post-treatment is required, which further increases the difficulty and cost of treatment.

Example 1 Comparative example 3 The difference between slow-release fillers Add paraffin omit paraffin Total nitrogen removal rate/% 81 40 Total phosphorus removal rate/% 100 77 Concentration of effluent SO₄^2-/mg/L 70-90 150-200 Effluent pH 7.1-7.5 5.7-6.1

In conjunction with the comparison of Example 1 (adding paraffin) and comparative example 3 (omitting paraffin), it can be seen that comparative example 3 (omitting paraffin) alone utilizes sulfur as the sulfate radical produced by the denitrification electron donor compared with Example 1 (adding paraffin) Significantly increased (increased by 60-130mg/L), and the effluent was acidic, increasing the difficulty of subsequent treatment.

Claims (8)

1. The synchronous nitrogen and phosphorus removal slow-release filler is characterized in that the filler is formed by wrapping an inner core slow-release layer with an outer permeable layer;

the inner core slow release layer consists of 10-40 parts of phosphorus removal active components, 20-50 parts of paraffin and 20-50 parts of sulfur powder;

the outer permeable layer consists of 20-50 parts of sulfur powder, 20-50 parts of paraffin and 15-35 parts of inorganic dispersant;

the phosphorus removal active component is selected from one or more of ferric salt, magnesium salt and aluminum salt;

the preparation process of the filler comprises the following steps:

1) Weighing the raw materials of the components according to the raw material proportion of the core slow-release layer, uniformly mixing, heating and stirring to uniformly disperse the phosphorus removal active component in the paraffin melt, pouring into a mold, cooling and solidifying to obtain the core;

2) Weighing the raw materials of the components according to the raw material proportion of the outer permeable layer, uniformly mixing, heating and stirring to uniformly disperse the inorganic dispersing agent in the molten paraffin to obtain uniform molten paraffin;

3) Dipping the inner core obtained in the step 1) into the molten liquid in the step 2), and then taking out and condensing; and (3) repeating the dipping and condensing process in the step 3), and controlling the thickness of the outer permeable layer to obtain the slow-release filler with enhanced nitrogen and phosphorus removal performance.

2. The filler of claim 1, wherein the inner core slow-release layer is a sphere with a diameter of 2-3cm, and the outer layer permeable layer has a thickness of 0.1-0.5cm.

3. The filler of claim 1, wherein the phosphorus and nitrogen removal active component is selected from one or more of sulfates, chlorides and carbonates of iron, magnesium or aluminum.

4. The filler of claim 1, wherein 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 meshes.

5. The filler of claim 1, wherein the paraffin is sliced paraffin.

6. The slow-release filler for simultaneous phosphorus and nitrogen removal according to claim 1, wherein the heating temperature in step 1) is 70-90 ℃ and the stirring time is 20-30min.

7. The slow-release filler for simultaneous phosphorus and nitrogen removal according to claim 1, wherein the heating temperature in step 2) is 65-80 ℃ and the stirring time is 20-30min.

8. Use of the slow release filler according to any one of claims 1 to 7 in a water treatment process, wherein the slow release filler is directly used for denitrification and/or dephosphorization in a water body with a low carbon-nitrogen ratio in the water treatment process.

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