CN115724525A - Synchronous nitrogen and phosphorus removal slow-release filler and preparation method thereof - Google Patents
Synchronous nitrogen and phosphorus removal slow-release filler and preparation method thereof Download PDFInfo
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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
Technical Field
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.
Background
The over-standard nitrogen and phosphorus in the water body can cause eutrophication and other problems, and nitrogen and phosphorus removal becomes one of the important tasks facing wastewater treatment and environmental pollution control. Although the traditional biological denitrification technology is widely applied, a certain organic carbon source is required in the denitrification process. For water with low carbon nitrogen ratio (COD/TN (namely C: N < 5:1)), the carbon source is limited, the electron donor required by denitrification is insufficient, complete denitrification can not be completed, and the traditional biological treatment technology is often usedIt is difficult to achieve an ideal denitrification effect. In order to solve the problem of insufficient carbon source, an additional organic carbon source or an inorganic electron donor is usually required. The heterotrophic denitrification process with the added carbon source can generate alkalinity, the sludge amount is large, and the subsequent treatment difficulty is increased; furthermore, the amount of carbon source added is not easy to control, and may cause shortage or excess of carbon source. Currently, the most used inorganic electron donors include low-valence sulfur compounds, elemental iron and ferrous iron, hydrogen, and the like. The elemental sulfur becomes a commonly used inorganic electron donor due to the characteristics of no toxicity, easy transportation, high denitrification efficiency and the like, and the sulfur autotrophic denitrification can generate a large amount of H + Lowering the pH of the reaction system, resulting in a decrease in microbial activity, and producing a large amount of SO 4 2- 。
In the aspect of phosphorus removal, although the biological method can remove part of phosphorus, the improvement of the phosphorus removal efficiency is limited due to the limitation of sludge age. In order to achieve deep phosphorus removal, chemical phosphorus removal after biological treatment is often required. Phosphorus removal agents are usually dosed continuously using metering equipment. This not only increases the complexity of the process equipment, operations, but also increases the cost. The frequency of adding the agent can be reduced by adding the slow-release phosphorus removal agent. Therefore, some domestic and foreign research institutes begin to research and develop sustained-release phosphorus removal medicaments.
For example, in chinese patent CN 107082479A, an organic layer with a slow release function is wrapped outside an iron-based flocculant, the organic layer is formed by mixing carboxymethyl chitosan and soluble high polymer materials such as polyvinylpyrrolidone, polyacrylic acid, polyethylene oxide or polyacrylamide, and when the iron-based phosphorus removal flocculant with a slow release function is put into water, the organic layer wrapped outside the iron-based phosphorus removal flocculant is gradually dissolved along with the reaction, so that the iron-based flocculant is released through pores of the organic layer until the organic layer is completely dissolved. However, the organic component of the organic layer (1), i.e., the high molecular component, is dissolved in water, and suspended matter, precipitates and other organic components in water are also increased, resulting in secondary pollution. (2) Aiming at the change of the phosphorus load in water, the control of the release rate of the slow-release phosphorus removing agent and the balance of the phosphorus load in water are difficult, which may cause the waste of the phosphorus removing agent and the unqualified phosphorus removing effect of effluent. (3) Meanwhile, the prepared iron-based flocculant only can realize a dephosphorization effect and cannot simultaneously exert a denitrification effect.
Chinese patent CN 111977764A discloses a composite phosphorus removal agent for water treatment, which consists of 50-80 parts of phosphorus removal coagulant, 5-15 parts of hydroxypropyl methyl cellulose ether, 3-6 parts of ammonium molybdate coated aluminum potassium sulfate and 40-50 parts of tablet forming agent. The phosphorus removing agent utilizes hydroxypropyl methyl cellulose ether (HPMC) to form an outermost gel layer, and the hydroxypropyl methyl cellulose ether (HPMC) gel layer is gradually dissolved in the reaction process. (1) The hydroxypropyl methyl cellulose ether (HPMC) gel layer component is dissolved in water, and suspended matters, precipitates and other organic components in the water are increased, so that secondary pollution is caused. (2) The obtained composite phosphorus removing agent can only be suitable for removing phosphorus, and the denitrification effect can not be realized.
The biofilm technology is a high-efficiency biological treatment technology developed by utilizing microorganisms attached to and grown on a carrier. Generally, an inert organic or inorganic carrier is used as the biofilm carrier. Aiming at the difficult problem of deep nitrogen and phosphorus removal of sewage, whether a biomembrane carrier with active components can be adopted or not improves the space for attachment growth of microorganisms, provides electrons for the microorganisms, strengthens the nitrogen removal process under low C/N ratio and can also strengthen the removal of phosphorus by slow release of the phosphorus removal active components.
Based on the problems and disadvantages of the prior art, it is desirable to provide a sustained release tablet (1) having a good sustained release effect; (2) can be used as a microorganism attachment growth carrier; (3) and can synchronously realize the slow release filling of nitrogen removal and phosphorus removal; (4) in the treatment process, secondary pollution caused by decomposition of the outer layer material can be avoided.
Disclosure of Invention
In order to overcome the technical problems, the invention provides a synchronous nitrogen and phosphorus removal slow-release filler and a preparation method thereof, which are used for water quality purification, wherein the slow-release filler can be used as a carrier for microorganism attachment growth and can also provide a plurality of electron donors for microorganism denitrification nitrogen removal; meanwhile, the phosphorus removal agent also has the function of releasing phosphorus removal active components in a controlled manner to strengthen phosphorus removal; the water purification by the method can not introduce a large amount of organic components and inorganic components into water to cause secondary pollution.
The invention provides a synchronous nitrogen and phosphorus removal slow-release filler, which 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 dephosphorization active components, 20-50 parts of paraffin and 20-50 parts of sulfur powder;
in some preferred embodiments, the mass ratio of the phosphorus removal active component to the phosphorus removal active component is as follows: paraffin wax: sulfur powder = 2;
the outer permeable layer consists of 20-50 parts of sulfur powder, 20-50 parts of paraffin and 15-35 parts of inorganic dispersant;
in some preferred embodiments, the mass ratio of the sulfur powder to the sulfur powder is as follows: paraffin wax: inorganic dispersant = 4;
the slow release filler selects paraffin and sulfur as carriers, and the phosphorus removal active component is wrapped in the inner core slow release layer through the outer permeable layer in the double-layer structure; the effect of the carrier for controllably releasing the phosphorus removal active component is utilized to achieve the aim of continuously removing phosphorus.
Meanwhile, the sulfur powder is used as an inorganic electron donor, and the paraffin is used as a slow-release carbon source in a matching manner to provide an electron donor for denitrification reaction for microorganisms, so that the denitrification is enhanced, and the synergistic proceeding of the sulfur autotrophic denitrification and the heterotrophic denitrification is realized.
In addition, the outer permeable layer of the slow release filler is added with the inorganic dispersant, so that the release rate of the phosphorus removal component can be regulated and controlled, and the attached growth of microorganisms on the surface of the filler is facilitated.
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 each component 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 paraffin molten liquid to obtain uniform molten liquid;
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 (4) 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 the enhanced nitrogen and phosphorus removal performance.
In some preferred embodiments, the inner core slow release layer of the filler is a sphere of 2-3cm diameter and the outer osmotic layer has a thickness of 0.1-0.5cm. The thickness of the outer permeable layer has obvious influence on the release rate of the phosphorus removal active component, the release rate is too slow when the thickness exceeds 0.5cm, the release of the phosphorus removal active component is greatly hindered, and the phosphorus removal efficiency is obviously reduced; below 0.1cm results in too fast a release rate and no sustained release effect.
In some preferred embodiments, the phosphorus removal active component is selected from one or more of sulfates, chlorides, 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 meshes.
In some preferred embodiments, the paraffin is a section paraffin.
In some preferred embodiments, the heating temperature in the step 1) is 70-90 ℃, and the stirring time is 20-30min.
In some preferred embodiments, the heating temperature in the step 2) is 65-80 ℃, and the stirring time is 20-30min.
In addition, the invention also provides an application of the slow release filler in a water treatment process, wherein the slow release filler is directly used for denitrification and/or dephosphorization in a water body in the water treatment process;
in some preferred embodiments, the ratio of COD to total mass of TN in the water body is COD: n is less than 5:1.
wherein, the total nitrogen removal rate reaches 72 to 81 percent, and the total phosphorus removal rate reaches 88 to 100 percent.
The invention has the beneficial effects that:
the invention provides a slow-release filler with a function of strengthening synchronous nitrogen and phosphorus removal and a preparation method thereof. The slow release filler utilizes paraffin and sulfur as carrier raw materials, and provides a plurality of electron donors for enhanced denitrification; through the design of a double-layer structure and the coating of the phosphorus removal active component, the carrier has the efficiency of releasing the phosphorus removal active component in a controlled manner, and the aim of continuously removing phosphorus is achieved.
(1) The dephosphorization active component has long slow release time, obvious slow release effect and can reach 200 days.
Insoluble paraffin and sulfur are used as coating carriers of the phosphorus removal active components, an outer permeable layer is adopted to coat a double-layer structure of the inner core slow release layer, the permeability is regulated and controlled by an inorganic dispersing agent, the release rate of the phosphorus removal active components is regulated and controlled by combining the processes of degrading the paraffin and the sulfur by microorganisms, the slow release rate of the phosphorus removal active components is effectively controlled, the time of the slow release of the active components by the carriers is long, and the time can reach 15-200 days.
(2) The raw materials of the slow-release filler can participate in water treatment reaction, and a large amount of organic components and inorganic components cannot be introduced to cause secondary pollution.
The main raw materials of the filler, namely paraffin and sulfur, are environment-friendly, non-toxic and harmless, wherein the paraffin is used as a slow-release carbon source and can provide a carbon source and electrons for biological denitrification, the paraffin can be degraded and mineralized biologically, the sulfur is used as an inorganic electron donor and can be utilized by sulfur autotrophic bacteria for denitrification, no toxic and harmful byproducts are generated in the biodegradation process of the paraffin and the sulfur, and compared with a method using a high-molecular organic material as a coating carrier, the method is environment-friendly and has no secondary environmental pollution.
(3) The slow release filler has a composite function, not only serves as a carrier for the attachment growth of microorganisms, but also has the functions of enhancing denitrification (the total nitrogen removal rate is up to 81 percent) and dephosphorization (the total phosphorus removal rate is up to 100 percent), and the carrier has the advantages of simple preparation method, flexible application and strong expansibility.
The carrier functions are as follows:
inorganic dispersing agents with good permeability and biological affinity are added into the outer permeable layer structure, so that the attachment growth of microorganisms on the surface of the filler at the initial stage of reaction can be accelerated.
The nitrogen and phosphorus removal function is as follows:
(1) denitrification: the sulfur powder is used as an inorganic electron donor, and the paraffin is used as a slow-release carbon source in a matching manner, so that various electron donors of denitrification reactions are provided for microorganisms, further, the denitrification is enhanced, the synergistic proceeding of sulfur autotrophic denitrification and heterotrophic denitrification reactions is realized, and no additional electron donor is required to be added. Wherein the content of the first and second substances,
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) And (3) dephosphorization: according to the invention, the high-efficiency phosphorus removal active component loaded by the double-layer structure and the inner core slow release layer is utilized, and the slow dissolution of the inner layer and the outer layer is utilized, so that the release speed of the phosphorus removal active component is effectively controlled, the slow release effect is realized, and the continuous phosphorus removal effect is achieved; meanwhile, the effect of the outer layer of the permeable layer material is utilized, and through the effects of adsorption, ion exchange, complexation and the like, phosphorus is further removed on the basis of not adding phosphorus removal active components, so that the aim of strengthening phosphorus removal is fulfilled.
(4) The slow-release filler disclosed by the invention synchronously realizes the nitrogen and phosphorus removal functions, remarkably reduces the generation amount of sulfate ions and sludge in a water body, ensures the pH value balance of the water body, and further reduces the possibility of secondary pollution.
The sulfur autotrophic denitrification and the paraffin-mediated heterotrophic denitrification reaction are coordinated for denitrification, so that the problem of overhigh generation amount of sulfate radicals caused by the sulfur autotrophic denitrification reaction is solved, the pH value of the effluent is effectively balanced, and the post-treatment process of a water body is not needed; compared with the separate paraffin-mediated heterotrophic denitrification technology, the method also reduces the generation of excess sludge.
Description of the drawings:
fig. 1 is a graph of the release rates of the filler phosphorus removal active components prepared in example 1 and comparative example 1.
FIG. 2 is a graph of the effect of continuous operation phosphorus removal of the filler prepared in example 1.
FIG. 3 is a graph showing the denitrification effect of the filler produced in example 1 in a continuous operation.
The specific implementation mode is as follows:
the present invention will be further described with reference to the following specific examples and fig. 1 to 3, but the scope of the invention is not limited to the examples, and any other products in various forms can be obtained by the teaching of the present invention, and any changes in the shape or the component ratio thereof, which are the same or similar to the technical solution of the present invention, fall within the scope of the present invention.
Example 1
1) The sulfur powder is prepared from the following raw materials in parts by mass: iron chloride: the preparation method comprises the following steps of weighing raw materials of paraffin = 30.
2) And (3) sulfur powder according to the mass ratio of the raw materials of the outer permeable layer: paraffin wax: the preparation method comprises the following steps of (1) weighing raw materials of the components of the activated carbon = 40.
3) Dipping the kernel 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 be 0.2cm to obtain the slow-release filler with enhanced nitrogen and phosphorus removal performance.
Wherein the granularity of the sulfur powder taken from the raw materials is 100 meshes, and the granularity of the active carbon taken from the raw materials is 100 meshes.
The slow release filler prepared by the method is used for an experiment for exploring the release rate of the phosphorus removal active component, the accumulated release rate of the slow release filler is shown in figure 1, the accumulated release rate in 20 days is about 10%, and the release period of the phosphorus removal component of the double-layer slow release filler can reach 200 days.
The prepared slow-release filler is filled into a reactor with the inner diameter of 6cm and the height of 100cm, microorganisms are inoculated to explore the continuous flow synchronous nitrogen and phosphorus removal effect, the attached figure 2 is a graph of the continuous operation phosphorus removal effect of the prepared filler, and the phosphate removal rate is over 95 percent. The nitrogen concentration of the prepared influent nitrate is 20mg/L, the ammonia nitrogen is 5mg/L, the phosphorus concentration is 2mg/L, the COD is 40mg/L, the hydraulic retention time is 4h, and the attached figure 3 is a pollutant removal effect diagram during continuous flow operation in a reactor, wherein the total nitrogen removal rate reaches 81 percent, and the total phosphorus removal rate reaches 100 percent.
Reactor effluent SO 4 2- The concentration is 70-90mg/L, the pH is 7.1-7.5, the effluent is maintained to be nearly neutral, the COD of the effluent is 10-20mg/L, and secondary organic pollution is not caused.
Example 2
1) The sulfur powder is prepared from the following raw materials in parts by mass: magnesium chloride: paraffin =20, weighing the raw materials, mixing uniformly, heating to 80 ℃ to melt the paraffin, stirring for 25min to uniformly disperse the phosphorus removal active component iron chloride in the melt, pouring the melt into a mold, selecting a spherical mold with the diameter of 2cm, and cooling and solidifying to obtain the inner core.
2) And (3) sulfur powder according to the mass ratio of the raw materials of the outer permeable layer: paraffin wax: active carbon =35, 20.
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 be 0.3cm to obtain the slow-release filler with enhanced nitrogen and phosphorus removal performance.
Wherein the granularity of the sulfur powder taken from the raw materials is 100 meshes, and the granularity of the active carbon taken from the raw materials is 200 meshes.
The prepared slow release filler is used for an experiment for 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.
The prepared slow-release filler is filled into a reactor with the inner diameter of 6cm and the height of 100cm, and microorganisms are inoculated to explore the continuous flow synchronous nitrogen and phosphorus removal effect. The nitrogen concentration of the prepared influent nitrate is 20mg/L, the ammonia nitrogen is 5mg/L, the phosphorus concentration is 3mg/L, the COD is 40mg/L, the hydraulic retention time is 4 hours, the total nitrogen removal rate reaches 72 percent, and the total phosphorus removal rate reaches 88 percent.
Reactor effluent SO 4 2- The concentration is 72-93mg/L, the pH is 7.0-7.5, the outlet water is maintained to be nearly neutral, the COD of the outlet water is 11-22mg/L, and secondary organic pollution can not be caused.
Example 3
1) The sulfur powder is prepared from the following raw materials in parts by mass: iron carbonate: and paraffin =35, weighing the raw materials, mixing uniformly, heating to 85 ℃ to melt the paraffin, stirring for 30min to uniformly disperse the phosphorus removal active component iron chloride in the melt, pouring the melt into a mold, selecting a spherical mold with the diameter of 3cm, and cooling and solidifying to obtain the inner core.
2) And (3) sulfur powder according to the mass ratio of the raw materials of the outer permeable layer: paraffin wax: fine sand = 20.
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 be 0.5cm to obtain the slow-release filler with enhanced nitrogen and phosphorus removal performance.
Wherein the granularity of the sulfur powder taken from the raw materials is 200 meshes, and the granularity of the active carbon taken from the raw materials is 100 meshes.
The prepared slow release filler is used for an experiment for 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 190 days.
The prepared slow-release filler is filled into a reactor with the inner diameter of 6cm and the height of 100cm, and microorganisms are inoculated to explore the continuous flow synchronous nitrogen and phosphorus removal effect. The nitrogen concentration of the prepared influent nitrate is 30mg/L, the ammonia nitrogen is 5mg/L, the phosphorus concentration is 2mg/L, the COD is 60mg/L, the hydraulic retention time is 4 hours, the total nitrogen removal rate reaches 77 percent, and the total phosphorus removal rate reaches 94 percent.
Reactor effluent SO 4 2- The concentration is 68-91mg/L, the pH is 6.9-7.6 to maintain the outlet water to be nearly neutral, the COD of the outlet water is 13-24mg/L, and secondary organic pollution can not be caused.
Example 4
1) The sulfur powder is prepared from the following raw materials in parts by mass: aluminum sulfate: and paraffin =50, weighing the raw materials, uniformly mixing, heating to 70 ℃ to melt the paraffin, stirring for 26min to uniformly disperse the phosphorus removal active component iron chloride in the melt, pouring the melt into a mold, selecting a spherical mold with the diameter of 2.6cm, and cooling and solidifying to obtain the inner core.
2) And (3) sulfur powder according to the mass ratio of the raw materials of the outer permeable layer: paraffin wax: fine sand = 50.
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 be 0.4cm to obtain the slow-release filler with enhanced nitrogen and phosphorus removal performance.
Wherein the granularity of the sulfur powder taken from the raw materials is 100 meshes, and the granularity of the active carbon taken from the raw materials is 100 meshes.
The prepared slow release filler is used for an experiment for 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 170 days.
The prepared slow release filler is filled into a reactor with the inner diameter of 6cm and the height of 100cm, and is inoculated with microorganisms to explore the continuous flow synchronous nitrogen and phosphorus removal effect. The nitrogen concentration of the prepared influent nitrate is 20mg/L, the ammonia nitrogen is 10mg/L, the phosphorus concentration is 4mg/L, the COD is 50mg/L, the hydraulic retention time is 4 hours, the total nitrogen removal rate reaches 76%, and the total phosphorus removal rate reaches 91%.
Reactor effluent SO 4 2- The concentration is 75-87mg/L, the pH is 7.2-7.7 to maintain the outlet water to be nearly neutral, the COD of the outlet water is 15-26mg/L, and secondary organic pollution can not be caused.
Comparative example 1
The single-layer slow-release filler is prepared by adopting the same raw materials and preparation process of the inner core slow-release layer as those in the example 1. The specific method comprises the following steps:
according to the mass ratio, the sulfur powder: aluminum chloride: weighing raw materials of paraffin =30, uniformly mixing, heating to 75 ℃, stirring for 25min, pouring into a spherical mold, wherein the diameter of the selected spherical mold is 2.5cm, and cooling and solidifying to obtain the single-layer slow-release filler.
The granularity of the sulfur powder is 100 meshes, and the granularity of the active carbon is 100 meshes.
The slow release filler prepared by the method is used for an experiment for researching the release rate of the phosphorus removal active component, the accumulated release rate is shown in figure 1, the accumulated release rate is as high as about 85% only in 15 days, the release is complete basically, and the slow release effect is poor.
As can be seen from the comparison and table 1 and fig. 1, in the time required for completely releasing the phosphorus removal active components of the comparative example 1 (single-layer structure) and the slow release filler of the example 1 (double-layer structure), the time consumed by the comparative example 1 (single-layer structure) is only about 15 days, while the cumulative release rate in example 1 for 20 days is about 10%, the complete release period of the phosphorus removal active components of the double-layer slow release filler is 200 days, the slow release effect of the example 1 (double-layer structure) is improved by more than 185 days compared with that of the comparative example 1 (single-layer structure), and the slow release effect is remarkably improved.
TABLE 1 Release Rate of phosphorus removal active component in example 1 and comparative example 1
Comparative example 2
Comparative example 2 differs from example 1 in that the addition of sulfur powder is omitted.
The method comprises the following specific steps:
1) According to the mass ratio of the raw materials of the inner core slow-release layer, ferric chloride: and (2) weighing the raw materials of the components, uniformly mixing, heating to 75 ℃ to melt the paraffin, stirring for 25min to uniformly disperse the phosphorus removal active component iron chloride in the molten liquid, pouring the molten liquid into a mold, and cooling and solidifying to obtain the inner core, wherein the diameter of the selected spherical mold is 2.5 cm.
2) According to the mass ratio of the raw materials of the outer permeable layer, paraffin: weighing raw materials of each component, uniformly mixing, heating to 70 ℃, melting paraffin, stirring for 23min, and uniformly dispersing an inorganic dispersant in the molten liquid to obtain a uniform molten liquid, wherein the raw materials of each component are activated carbon = 25.
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 be 0.2cm to obtain the slow-release filler with enhanced nitrogen and phosphorus removal performance.
Wherein the granularity of the sulfur powder taken from the raw materials is 100 meshes, and the granularity of the active carbon taken from the raw materials is 100 meshes.
The prepared slow release filler is used for an experiment for 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.
The prepared slow-release filler is filled into a reactor with the inner diameter of 6cm and the height of 100cm, and microorganisms are inoculated to explore the continuous flow synchronous nitrogen and phosphorus removal effect. The nitrogen concentration of the prepared influent nitrate is 20mg/L, the ammonia nitrogen is 5mg/L, the phosphorus concentration is 3mg/L, the COD is 40mg/L, the hydraulic retention time is 4 hours, the total nitrogen removal rate is 44 percent, and the total phosphorus removal rate is 72 percent.
After the water treatment is finished, discharging water SO from the reactor 4 2- The concentration is 20-30mg/L (the background value when water is distributed), and the pH is 8.1-8.6. The alkalinity improvement range of the effluent quality is obviously increased, and the nearly neutral discharge standard can not be realized.
| Example 1 | Comparative example 2 | |
| Differences in Slow Release fillers | Adding sulfur powder | Omitting sulfur powder |
| Total nitrogen removal/%) | 81 | 44 |
| Total |
100 | 72 |
| pH of the effluent | 7.1-7.5 | 8.1-8.6 |
By combining the comparison between the example 1 (adding sulfur powder) and the comparative example 2 (omitting sulfur powder), it can be seen that the addition of sulfur powder can be used as an inorganic electron donor to generate sulfur autotrophic denitrification, and the total nitrogen removal rate is remarkably improved. Compared with the comparative example 2 (omitting the sulfur powder), the total nitrogen removal rate of the example 1 (adding the sulfur powder) is improved by 40 percent; the improvement effect is obvious. Meanwhile, the phosphorus element in the water body can be completely removed in the embodiment 1 (adding the sulfur powder), the total phosphorus removal rate reaches 100%, the phosphorus element in the water body cannot be completely removed in the comparative example 2 (omitting the sulfur powder), and compared with the embodiment 1 (adding the sulfur powder), the total phosphorus removal rate of the comparative example 2 (omitting the sulfur powder) is reduced by 39%, and the reduction effect is obvious.
And, due to the occurrence of sulfur autotrophic denitrification reaction, H is further generated + The alkalinity generated by heterotrophic denitrification is balanced, the pH of the effluent is maintained to be nearly neutral, and the operation of subsequent treatment is reduced.
Comparative example 3
Comparative example 3 differs from example 1 in that the addition of paraffin wax was omitted and the melting temperature was raised to 115 ℃ during the preparation process, since the melting point of sulfur was 112.8 ℃.
The method comprises the following specific steps:
1) According to the mass ratio of the raw materials of the inner core slow-release layer, the sulfur powder: weighing the raw materials of each component, uniformly mixing, heating to 115 ℃ to melt sulfur powder, stirring for 25min to uniformly disperse the iron chloride serving as the phosphorus removal active component in molten liquid, pouring the molten liquid into a mold, and cooling and solidifying to obtain the inner core, wherein the diameter of the selected spherical mold is 2.5 cm.
2) According to the mass ratio of the raw materials of the outer permeable layer, the sulfur powder: weighing raw materials of each component, uniformly mixing, heating to 115 ℃, melting sulfur powder, stirring for 23min, and uniformly dispersing an inorganic dispersant in the molten liquid to obtain a uniform molten liquid, wherein the raw materials of each component are the following components.
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 (4) repeating the dipping and condensing process in the step 3), and controlling the thickness of the outer permeable layer to be 0.2cm to obtain the slow release filler with enhanced nitrogen and phosphorus removal performance.
Wherein the granularity of the sulfur powder taken from the raw materials is 100 meshes, and the granularity of the active carbon taken from the raw materials is 100 meshes.
The prepared slow release filler is used for an experiment for 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 170 days.
The prepared slow-release filler is filled into a reactor with the inner diameter of 6cm and the height of 100cm, and microorganisms are inoculated to explore the continuous flow synchronous nitrogen and phosphorus removal effect. The nitrogen concentration of the prepared influent nitrate is 20mg/L, the ammonia nitrogen is 5mg/L, the phosphorus concentration is 3mg/L, the COD is 40mg/L, the hydraulic retention time is 4 hours, the total nitrogen removal rate is 40 percent, and the total phosphorus removal rate is 77 percent.
After the water treatment is finished, discharging SO from the reactor 4 2- The concentration is 150-200mg/L, and the pH is 5.7-6.1. The pH acidity of the effluent is obviously enhanced, the nearly neutral discharge standard cannot be realized, and the post-treatment process is required, so that the treatment difficulty and the cost are further increased.
| Example 1 | Comparative example 3 | |
| Differences in Slow Release fillers | Adding paraffin wax | Omitting paraffin wax |
| Total nitrogen removal/%) | 81 | 40 |
| Total |
100 | 77 |
| Effluent SO 4 2- concentration/mg/L | 70-90 | 150-200 |
| pH of the effluent | 7.1-7.5 | 5.7-6.1 |
By combining the comparison between example 1 (paraffin addition) and comparative example 3 (paraffin omission), it can be seen that the sulfate radical generated by using sulfur alone as a denitrification electron donor in comparative example 3 (paraffin omission) is remarkably increased (increased by 60-130 mg/L) compared with example 1 (paraffin addition), and effluent is acidic, which increases 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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| CN202211488222.3A CN115724525A (en) | 2022-11-25 | 2022-11-25 | Synchronous nitrogen and phosphorus removal slow-release filler and preparation method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116332343A (en) * | 2023-05-22 | 2023-06-27 | 江苏省环境工程技术有限公司 | Sulfur autotrophic denitrification sulfur-based magnetic filler and preparation method and application thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116332343A (en) * | 2023-05-22 | 2023-06-27 | 江苏省环境工程技术有限公司 | Sulfur autotrophic denitrification sulfur-based magnetic filler and preparation method and application thereof |
| CN116332343B (en) * | 2023-05-22 | 2023-08-18 | 江苏省环境工程技术有限公司 | Sulfur autotrophic denitrification sulfur-based magnetic filler and preparation method and application thereof |
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