An autotrophic denitrification treatment process for sewage, its system and packing

Abstract

The present invention provides an autotrophic denitrification treatment process for sewage, as well as a system and a filler thereof. The autotrophic denitrification treatment process for sewage comprises the following steps: enabling the sewage to be treated to enter a sulfur autotrophic denitrification filter tank, controlling the empty bed residence time to be 1 - 3 h and the average filtration rate to be 0.5 - 5 m / h, and performing denitrification treatment by using a sulfur autotrophic denitrification filler loaded with denitrifying bacteria. The sulfur autotrophic denitrification filler comprises the following raw materials in parts by weight: 80 - 90 parts of sulfur, 0 - 5 parts of alumina, 5 - 10 parts of a pH buffer, 20 - 30 parts of quartz stone, 1 - 30 parts of a slow-release agent, and 1 - 5 parts of an adhesive. The autotrophic denitrification treatment process for sewage according to the present invention can maintain a stable denitrification effect and has a good nitrogen removal effect.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, in particular to an autotrophic denitrification treatment process for sewage, its system, and packing material. Background Art

[0002] In industrial sewage containing dimethylformamide (DMF), the total nitrogen concentration is generally relatively high, and the total nitrogen concentration can reach 200 mg / L. Denitrification is one of the biological treatment methods for nitrogen removal, and it can reduce the nitrogen in nitrate (NO3 - ) to nitrogen gas (N2) through a series of intermediate products by bacteria. The traditional heterotrophic denitrification technology removes nitrogen by adding a carbon source, and there are many problems in practical applications. The amount of carbon source added needs to be adapted to the content of nitrate (NO3 - ) in the influent. A higher C / N ratio will not only increase the economic investment but also cause the COD of the effluent to exceed the standard; insufficient C / N will result in the nitrogen removal effect not reaching the expected level. However, the content of nitrate (NO3 - ) in the influent often fluctuates. Therefore, it is difficult to control the appropriate amount of carbon source added.

[0003] To solve the above problems, the sulfur autotrophic denitrification technology can be used as an alternative in the prior art. The sulfur autotrophic denitrification technology uses inorganic sulfur compounds such as elemental sulfur and sulfide as electron donors, and uses CO3 2- , HCO3 - , CO2 as inorganic carbon sources, and uses the metabolic action of autotrophic microorganisms to reduce nitrate to nitrogen gas without the need to add additional organic carbon sources. However, the sulfur autotrophic denitrification technology in the prior art usually releases sulfur sources rapidly in a short time, resulting in too high a sulfur source concentration at the initial stage of the reaction, which inhibits the denitrifying microorganisms and affects their activity and metabolic process. In the later stage of the reaction, due to the rapid depletion of sulfur sources, it is difficult to continuously provide sufficient electron donors for the denitrification reaction, and it is difficult to maintain a stable denitrification effect.

[0004] In view of this, at present, for sewage with a high total nitrogen concentration, there is an urgent need to propose an autotrophic denitrification treatment process for sewage with a stable denitrification effect and good nitrogen removal effect. Summary of the Invention

[0005] The purpose of the present invention is to provide an autotrophic denitrification treatment process for sewage, its system, and packing material to solve the problems that the sulfur autotrophic denitrification process in the prior art is difficult to maintain a stable denitrification effect and has a poor nitrogen removal effect.

[0006] The present invention provides the following technical solutions:

[0007] A sulfur autotrophic denitrification packing material, comprising raw materials in the following parts by weight:

[0008] 80 - 90 parts of sulfur, 0 - 5 parts of aluminum oxide, 5 - 10 parts of pH buffer, 20 - 30 parts of quartz stone, 1 - 30 parts of slow-release agent, 1 - 5 parts of binder;

[0009] Among them, the slow-release agent is a composite material formed by tungsten disulfide treated with an intercalating agent and a polymer, and the polymer includes polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran.

[0010] Preferably, the slow-release agent is obtained by the following method: adding tungsten disulfide and an intercalating agent to water, mixing evenly to obtain tungsten disulfide treated with the intercalating agent, and then adding a polymer thereto. After reaction, filtration, washing, and drying are carried out.

[0011] Preferably, the slow-release agent is specifically obtained by the following method: adding tungsten disulfide and an intercalating agent to water, ultrasonic vibrating for 30 - 60 min to obtain tungsten disulfide treated with the intercalating agent, then adding a polymer and sulfuric acid thereto, stirring and reacting at 60 - 80 °C for 2 - 10 h, and then carrying out filtration, washing, and drying.

[0012] Preferably, the mass ratio of tungsten disulfide, intercalating agent, and polymer is 1:(0.01 - 0.1):(2 - 6);

[0013] Optionally, the polymer is a mixture of polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran in a mass ratio of 1:(1 - 10):(0.5 - 3.0);

[0014] Optionally, the concentration of tungsten disulfide in water is 5 - 10 g / ml;

[0015] Optionally, the mass ratio of sulfuric acid to the polymer is (0.2 - 1):100.

[0016] Preferably, the intercalating agent is one or more of dodecyltrimethylammonium chloride, tripropylmethylammonium chloride, and (2-mercaptoethyl)trimethylammonium chloride.

[0017] Preferably, the intercalating agent is a mixture of dodecyltrimethylammonium chloride, tripropylmethylammonium chloride, and (2-mercaptoethyl)trimethylammonium chloride.

[0018] Preferably, the intercalating agent is a mixture of dodecyltrimethylammonium chloride, tripropylmethylammonium chloride, and (2-mercaptoethyl)trimethylammonium chloride in a weight ratio of 3:1:0.8.

[0019] Preferably, the sulfur autotrophic denitrification filler is obtained by the following method:

[0020] (1) Take sulfur, aluminum oxide, pH buffer, quartz stone, slow-release agent, and binder, mix evenly to obtain a mixed raw material;

[0021] (2) Add water to the mixed raw materials in step (1) to obtain a mixed slurry;

[0022] (3) Granulate and dry the mixed slurry obtained in step (2) to obtain a sulfur autotrophic denitrification filler.

[0023] Preferably, in step (2), the weight ratio of the mixed raw materials to water is 1:(0.2 - 5);

[0024] Optionally, in step (3), the particle size of the granulation is 5 - 8 mm;

[0025] Optionally, in step (3), the drying temperature is 40 - 60 °C and the time is 2 - 3 h.

[0026] Preferably, the pH buffer is one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, and potassium hydroxide;

[0027] Optionally, the binder is one or more of SBS and SBR.

[0028] The present invention also provides a sewage autotrophic denitrification treatment process, including the following steps: allowing the sewage to be treated to enter a sulfur autotrophic denitrification filter, controlling the empty bed residence time to be 1 - 3 h and the average filtration rate to be 0.5 - 5 m / h, and performing denitrification treatment using the sulfur autotrophic denitrification filler loaded with denitrifying bacteria.

[0029] The present invention also provides a sewage autotrophic denitrification treatment system, at least including a sulfur autotrophic denitrification filter; the bottom of the sulfur autotrophic denitrification filter is provided with a water inlet, the top is provided with a water outlet, and a water distribution layer, a supporting layer, a filler layer, and a clear water layer are sequentially arranged inside from bottom to top;

[0030] The filler layer is filled with the sulfur autotrophic denitrification filler.

[0031] Preferably, the thickness of the filler layer is 3 - 4 m.

[0032] The above solution of the present invention has at least the following beneficial effects:

[0033] (1) The sewage autotrophic denitrification treatment process of the present invention includes the following steps: allowing the sewage to be treated to enter a sulfur autotrophic denitrification filter, controlling the empty bed residence time to be 1 - 3 h and the average filtration rate to be 0.5 - 5 m / h, and performing denitrification treatment using the sulfur autotrophic denitrification filler loaded with denitrifying bacteria. In the sewage autotrophic denitrification treatment process, by using a slow-release sulfur autotrophic denitrification filler, under the conditions of an appropriate empty bed residence time and filtration rate, the sulfur source maintains a relatively stable concentration during the denitrification treatment process, maintains a stable denitrification effect, and achieves a good nitrogen removal effect.

[0034] (2) The sulfur autotrophic denitrification filler of the present invention includes a slow-release agent. The presence of the slow-release agent can appropriately reduce the contact area between the inside of the filler and the sewage, prevent the sulfur source concentration from being too high at the initial stage of the reaction, inhibit the activity of denitrifying microorganisms, and during the reaction process, through the gradual digestion of the slow-release agent, the sulfur source in the filler is gradually dissolved, realizing the slow release of the sulfur source.

[0035] (3) The slow-release agent of the sulfur autotrophic denitrification filler of the present invention is obtained by the following method: adding tungsten disulfide and an intercalating agent into water, mixing evenly to obtain tungsten disulfide treated with the intercalating agent, and then adding a polymer thereto. After the reaction, filtration, washing, and drying are carried out. Among them, the intercalating agent is one or more of dodecyltrimethylammonium chloride and tripropylmethylammonium chloride. The polymer includes polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran.

[0036] The tungsten disulfide has a layered structure and poor dispersibility in water. The quaternary ammonium cation group of the intercalating agent can be inserted into the interlayer of the tungsten disulfide under electrostatic action, preventing the aggregation of the tungsten disulfide. When the intercalating agent is dodecyltrimethylammonium chloride, the flexible hydrophobic chain of the dodecyltrimethylammonium chloride is exposed outside the interlayer of the tungsten disulfide and can be adsorbed to the hydrophobic polycaprolactone through hydrophobic interaction; when the intercalating agent is tripropylmethylammonium chloride, the shorter propyl chain is more likely to be inserted into the interlayer of the tungsten disulfide, which helps to improve the intercalation efficiency; when the intercalating agent is (2-mercaptoethyl)trimethylammonium chloride, on the one hand, the mercapto group it has has certain reaction activity, which can introduce reaction sites in the interlayer and generate a cross-linking reaction with aldehyde-modified dextran. On the other hand, the sulfur atom in the mercapto group has a lone pair of electrons, and the tungsten atoms and sulfur atoms on the surface of the tungsten disulfide have empty orbitals. The presence of the mercapto group can make it bind more firmly to the interlayer of the tungsten disulfide. When both dodecyltrimethylammonium chloride and tripropylmethylammonium chloride are used together, the long-chain alkyl group of the dodecyltrimethylammonium chloride can form a more regular arrangement in the interlayer of the tungsten disulfide, providing better spatial support, while the short alkyl chain of the tripropylmethylammonium chloride can fill the voids, making the distribution of the intercalating agent in the interlayer more uniform, thereby optimizing the interlayer structure of the tungsten disulfide.

[0037] After adding the polymer, on the one hand, under the state of heating and stirring, the movement of the polyvinyl alcohol molecular chains is intensified, and entanglements will occur between the molecular chains, which is conducive to entangling with the flexible chains exposed outside the interlayers of the tungsten disulfide and the adsorbed polycaprolactone; on the other hand, the aldehyde-functionalized dextran can react with the polyvinyl alcohol to crosslink. Therefore, the polycaprolactone, polyvinyl alcohol, and aldehyde-functionalized dextran can form a crosslinked structure on the surface and between the layers of the tungsten disulfide, thereby forming a composite material. The resulting sustained-release agent can not only be gradually decomposed in water to achieve the sustained release of the sulfur source, but also the layer structure of the tungsten disulfide can provide more attachment sites for denitrifying microorganisms, which is beneficial to improving the denitrification efficiency. Brief Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0039] Figure 1 It is a schematic structural diagram of the sewage autotrophic denitrification treatment system of the present invention.

[0040] Among them, 1. Sulfur autotrophic denitrification filter; 11. Water inlet; 12. Water outlet; 13. Water distribution layer; 14. Support layer; 15. Packing layer; 16. Clear water layer. Detailed Embodiments

[0041] In the embodiments of the present invention, those not specified in specific conditions are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase. The raw materials of different manufacturers and models do not affect the implementation of the technical solutions of the present invention and the realization of the technical effects.

[0042] It should be noted that the adhesives used in the following embodiments are SBS and SBR, which are conventional products in the prior art. For example, products the same as those disclosed in the adhesive of Chinese patent document CN118359322B can be used.

[0043] In the following embodiments, the aldehyde-functionalized dextran is a conventional product in the prior art and can be prepared by the prior art. For example, it can be prepared by the sodium periodate oxidation method. Specifically, it can be obtained by the following method: Add sodium periodate to the dextran solution, stir and react in the dark at room temperature, add ethylene glycol, then dialyze with deionized water, and freeze-dry the dialysate to obtain the aldehyde-functionalized dextran.

[0044] In the following examples, the CAS number of dodecyltrimethylammonium chloride is 112-00-5; the CAS number of tripropylmethylammonium chloride is 75373-66-9; the CAS number of (2-mercaptoethyl)trimethylammonium chloride is 37880-96-9.

[0045] Example 1

[0046] The sulfur autotrophic denitrification filler of this example comprises raw materials in the following parts by weight:

[0047] 80 parts of sulfur, 8 parts of pH buffer, 30 parts of quartz stone, 15 parts of slow-release agent, 1 part of binder;

[0048] Among them, the slow-release agent is a composite material formed by tungsten disulfide treated with an intercalating agent and a polymer. The polymer includes polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran. The intercalating agent is dodecyltrimethylammonium chloride. The pH buffer is sodium carbonate; the binder is SBS.

[0049] The sulfur autotrophic denitrification filler described in this example is obtained by the following method:

[0050] (1) Take sulfur, pH buffer, quartz stone, slow-release agent, and binder, mix them evenly to obtain a mixed raw material;

[0051] (2) Add water to the mixed raw material in step (1) to obtain a mixed slurry; among them, the weight ratio of the mixed raw material to water is 1:3;

[0052] (3) Granulate and dry the mixed slurry obtained in step (2) to obtain the sulfur autotrophic denitrification filler.

[0053] Among them, the particle size of the granulation is 5 mm; the drying temperature is 50 °C, and the time is 2 h.

[0054] In this example, the slow-release agent is specifically obtained by the following method: Add tungsten disulfide and an intercalating agent to water, ultrasonic oscillate for 45 min to obtain tungsten disulfide treated with an intercalating agent, then add a polymer and sulfuric acid thereto, stir and react at 60 °C for 10 h, and then filter, wash, and dry to obtain.

[0055] Among them, the mass ratio of tungsten disulfide, intercalating agent, and polymer is 1:0.01:6; the polymer is a mixture of polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran in a mass ratio of 1:5:1.6; the concentration of tungsten disulfide in water is 5 g / ml; the mass ratio of sulfuric acid to the polymer is 1:100.

[0056] The autotrophic denitrification treatment process for sewage in this embodiment includes the following steps: enabling the sewage to be treated to enter a sulfur autotrophic denitrification filter, controlling the empty bed residence time to be 1 h and the average filtration rate to be 2.5 m / h, and performing denitrification treatment using the sulfur autotrophic denitrification filler loaded with denitrifying bacteria.

[0057] Example 2

[0058] The sulfur autotrophic denitrification filler in this embodiment includes the following raw materials in parts by weight:

[0059] 90 parts of sulfur, 5 parts of alumina, 5 parts of pH buffer, 25 parts of quartz stone, 1 part of slow-release agent, 5 parts of binder;

[0060] Among them, the slow-release agent is a composite material formed by tungsten disulfide treated with an intercalating agent and a polymer, and the polymer includes polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran. The intercalating agent is tripropylmethylammonium chloride. The pH buffer is sodium bicarbonate; the binder is SBR.

[0061] The sulfur autotrophic denitrification filler in this embodiment is obtained through the following method:

[0062] (1) Take sulfur, alumina, pH buffer, quartz stone, slow-release agent, and binder, mix them evenly to obtain a mixed raw material;

[0063] (2) Add water to the mixed raw material in step (1) to obtain a mixed slurry; among them, the weight ratio of the mixed raw material to water is 1:5;

[0064] (3) Granulate and dry the mixed slurry obtained in step (2) to obtain the sulfur autotrophic denitrification filler.

[0065] Among them, the particle size of the granulation is 8 mm; the drying temperature is 60 °C and the time is 3 h.

[0066] In this embodiment, the slow-release agent is specifically obtained through the following method: Add tungsten disulfide and an intercalating agent to water, ultrasonically vibrate for 60 min to obtain tungsten disulfide treated with an intercalating agent, then add a polymer and sulfuric acid thereto, stir and react at 70 °C for 2 h, and then perform filtration, washing, and drying.

[0067] Among them, the mass ratio of tungsten disulfide, intercalating agent, and polymer is 1:0.1:4; the polymer is a mixture of polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran in a mass ratio of 1:1:3; the concentration of tungsten disulfide in water is 10 g / ml; the mass ratio of sulfuric acid to the polymer is 0.6:100.

[0068] The autotrophic denitrification treatment process for sewage in this embodiment includes the following steps: allowing the sewage to be treated to enter a sulfur autotrophic denitrification filter, controlling the empty bed residence time at 2 h and the average filtration rate at 0.5 m / h, and performing denitrification treatment using the sulfur autotrophic denitrification filler loaded with denitrifying bacteria.

[0069] Example 3

[0070] The sulfur autotrophic denitrification filler in this embodiment includes the following raw materials in parts by weight:

[0071] 85 parts of sulfur, 2.5 parts of alumina, 10 parts of pH buffer, 20 parts of quartz stone, 30 parts of slow-release agent, 3 parts of binder;

[0072] Among them, the slow-release agent is a composite material formed by tungsten disulfide treated with an intercalating agent and a polymer. The polymer includes polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran. The intercalating agent is dodecyltrimethylammonium chloride. The pH buffer is a mixture of sodium carbonate and sodium hydroxide in a weight ratio of 1:1; the binder is SBS.

[0073] The sulfur autotrophic denitrification filler in this embodiment is obtained through the following method:

[0074] (1) Take sulfur, alumina, pH buffer, quartz stone, slow-release agent, and binder, mix them evenly to obtain a mixed raw material;

[0075] (2) Add water to the mixed raw material in step (1) to obtain a mixed slurry; among them, the weight ratio of the mixed raw material to water is 1:0.2;

[0076] (3) Granulate and dry the mixed slurry obtained in step (2) to obtain the sulfur autotrophic denitrification filler.

[0077] Among them, the particle size of the granulation is 6 mm; the drying temperature is 40 °C and the time is 3 h.

[0078] In this embodiment, the slow-release agent is specifically obtained through the following method: Add tungsten disulfide and the intercalating agent to water, ultrasonically vibrate for 30 min to obtain tungsten disulfide treated with the intercalating agent, then add the polymer and sulfuric acid thereto, stir and react at 80 °C for 6 h, and then perform filtration, washing, and drying.

[0079] Among them, the mass ratio of tungsten disulfide, the intercalating agent, and the polymer is 1:0.05:2; the polymer is a mixture of polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran in a mass ratio of 1:10:0.5; the concentration of tungsten disulfide in water is 7 g / ml; the mass ratio of sulfuric acid to the polymer is 0.2:100.

[0080] The autotrophic denitrification treatment process of this embodiment includes the following steps: allowing the sewage to be treated to enter the sulfur autotrophic denitrification filter, controlling the empty bed residence time at 3 h and the average filtration rate at 5 m / h, and performing denitrification treatment using the sulfur autotrophic denitrification filler loaded with denitrifying bacteria.

[0081] Example 4

[0082] The sulfur autotrophic denitrification filler of this embodiment includes the following raw materials in parts by weight:

[0083] 85 parts of sulfur, 3 parts of alumina, 8 parts of pH buffer, 25 parts of quartz stone, 25 parts of slow-release agent, 3 parts of binder;

[0084] Among them, the slow-release agent is a composite material formed by tungsten disulfide treated with an intercalating agent and a polymer, and the polymer includes polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran. The intercalating agent is a mixture of dodecyltrimethylammonium chloride and tripropylmethylammonium chloride in a mass ratio of 3:1. The pH buffer is a mixture of sodium bicarbonate and sodium hydroxide in a mass ratio of 1:1; the binder is SBS.

[0085] The sulfur autotrophic denitrification filler of this embodiment is obtained by the following method:

[0086] (1) Take sulfur, alumina, pH buffer, quartz stone, slow-release agent, and binder, mix them evenly to obtain a mixed raw material;

[0087] (2) Add water to the mixed raw material in step (1) to obtain a mixed slurry; among them, the weight ratio of the mixed raw material to water is 1:3;

[0088] (3) Granulate and dry the mixed slurry obtained in step (2) to obtain the sulfur autotrophic denitrification filler.

[0089] Among them, the particle size of the granulation is 6 mm; the drying temperature is 50 °C and the time is 3 h.

[0090] In this embodiment, the slow-release agent is specifically obtained by the following method: Add tungsten disulfide and an intercalating agent to water, ultrasonically vibrate for 60 min to obtain tungsten disulfide treated with an intercalating agent, then add a polymer and sulfuric acid thereto, stir and react at 70 °C for 8 h, and then perform filtration, washing, and drying.

[0091] Among them, the mass ratio of tungsten disulfide, intercalating agent, and polymer is 1:0.06:5; the polymer is a mixture of polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran in a mass ratio of 1:3:2; the concentration of tungsten disulfide in water is 8 g / ml; the mass ratio of sulfuric acid to the polymer is 0.8:100.

[0092] The autotrophic denitrification treatment process for sewage in this embodiment includes the following steps: allowing the sewage to be treated to enter a sulfur autotrophic denitrification filter, controlling the empty bed residence time at 2.5 h and the average filtration rate at 3.5 m / h, and performing denitrification treatment using the sulfur autotrophic denitrification filler loaded with denitrifying bacteria.

[0093] As a specific implementation manner of this embodiment, the operating temperature of the denitrification treatment is 20 °C, and the designed nitrate nitrogen load is 0.5 kg TN / m³ filler·d.

[0094] Example 5

[0095] The autotrophic denitrification treatment system for sewage in this embodiment at least includes a sulfur autotrophic denitrification filter; as Figure 1 shown, it is a structural schematic diagram of the sulfur autotrophic denitrification filter. The bottom of the sulfur autotrophic denitrification filter 1 is provided with a water inlet 11, the top is provided with a water outlet 12, and the interior is sequentially provided with a water distribution layer 13, a supporting layer 14, a filler layer 15, and a clear water layer 16 from bottom to top; the filler layer 15 is filled with sulfur autotrophic denitrification filler. The thickness of the filler layer 15 is 3 m.

[0096] The working process of the autotrophic denitrification treatment system for sewage in this embodiment is as follows: the sewage to be treated enters the sulfur autotrophic denitrification filter from the water inlet 11, passes through the water distribution layer 13 and the supporting layer 14, enters the filler layer 15, stays for a preset time, and then flows out from the water outlet 12 through the clear water layer 1.

[0097] Example 6

[0098] The sulfur autotrophic denitrification filler in this embodiment is the same as that used in Example 4 in terms of raw materials and the dosage of each raw material, and is prepared by the same method. The only difference is that the intercalating agent is a mixture of dodecyltrimethylammonium chloride, tripropylmethylammonium chloride, and (2-mercaptoethyl)trimethylammonium chloride in a weight ratio of 3:1:0.8.

[0099] The autotrophic denitrification treatment process for sewage in this embodiment is the same as that in Example 4.

[0100] Comparative Example 1

[0101] The sulfur autotrophic denitrification filler in this comparative example is the same as that used in Example 4 in terms of raw materials and the dosage of each raw material, and is prepared by the same method. The only difference is that it does not contain the slow-release agent.

[0102] The autotrophic denitrification treatment process for sewage in this comparative example is the same as that in Example 4.

[0103] Comparative Example 2

[0104] The sulfur autotrophic denitrification filler of this comparative example uses the same raw materials and the same amounts of each raw material as those used in Example 4, and is prepared by the same method. The only difference is that the polymer is a mixture of polycaprolactone and polyvinyl alcohol in a mass ratio of 1:3.

[0105] The sewage autotrophic denitrification treatment process of this comparative example is the same as that of Example 4.

[0106] Comparative Example 3

[0107] The sulfur autotrophic denitrification filler of this comparative example uses the same raw materials and the same amounts of each raw material as those used in Example 4, and is prepared by the same method. The only difference is that the polymer is a mixture of polycaprolactone and aldehyde group-containing dextran in a mass ratio of 1:2.

[0108] The sewage autotrophic denitrification treatment process of this comparative example is the same as that of Example 4.

[0109] Comparative Example 4

[0110] The sulfur autotrophic denitrification filler of this comparative example uses the same raw materials and the same amounts of each raw material as those used in Example 4, and is prepared by the same method. The only difference is that the polymer is a mixture of polyvinyl alcohol and aldehyde group-containing dextran in a mass ratio of 3:2.

[0111] The sewage autotrophic denitrification treatment process of this comparative example is the same as that of Example 4.

[0112] Comparative Example 5

[0113] The sulfur autotrophic denitrification filler of this comparative example uses the same raw materials and the same amounts of each raw material as those used in Example 4, and is prepared by the same method. The only difference is that the slow-release agent is tungsten disulfide treated with an intercalating agent and does not contain the polymer.

[0114] In this comparative example, the slow-release agent is obtained by the following method: adding tungsten disulfide and an intercalating agent to water, ultrasonic vibrating for 60 min, filtering and drying.

[0115] The sewage autotrophic denitrification treatment process of this comparative example is the same as that of Example 4.

[0116] Comparative Example 6

[0117] The sulfur autotrophic denitrification filler of this comparative example uses the same raw materials and the same amounts of each raw material as those used in Example 4, and is prepared by the same method. The only difference is that the slow-release agent is a composite material formed by tungsten disulfide not treated with an intercalating agent and the polymer.

[0118] In this comparative example, the sustained-release agent is obtained by the following method: Tungsten disulfide is added to water, and ultrasonic oscillation is performed for 60 min. Then, a polymer and sulfuric acid are added thereto, and after stirring and reacting at 70°C for 8 h, filtration, washing, and drying are performed to obtain the product.

[0119] The autotrophic denitrification treatment process for wastewater in this comparative example is the same as that in Example 4.

[0120] Comparative Example 7

[0121] The sulfur autotrophic denitrification filler in this comparative example is prepared from the same raw materials and in the same amounts as those used in Example 4, and by the same method, except that the intercalating agent is dodecyltrimethylammonium chloride.

[0122] The autotrophic denitrification treatment process for wastewater in this comparative example is the same as that in Example 4.

[0123] Comparative Example 8

[0124] The sulfur autotrophic denitrification filler in this comparative example is prepared from the same raw materials and in the same amounts as those used in Example 4, and by the same method, except that the intercalating agent is tripropylmethylammonium chloride.

[0125] The autotrophic denitrification treatment process for wastewater in this comparative example is the same as that in Example 4.

[0126] Effect Experimental Example

[0127] To verify the technical effects of the autotrophic denitrification treatment process, its system, and the filler of the present invention, the following tests are carried out:

[0128] The sulfur autotrophic denitrification fillers obtained in Examples 1-4, 6, and Comparative Examples 1-8 are respectively filled into the autotrophic denitrification treatment system in Example 5, and the wastewater to be treated is continuously treated according to the corresponding autotrophic denitrification treatment process. The quality of the wastewater to be treated is as follows: the concentration of nitrate nitrogen is 50 mg / L, COD < 30 mg / L, ammonia nitrogen < 1 mg / L, and TDS < 1000 mg / L. On the 3rd day, 15th day, and 30th day of continuous operation, the concentration of nitrate nitrogen in the treated effluent is measured, and the nitrate nitrogen removal rate is calculated to evaluate the denitrification effect. On the 1st day, 3rd day, 9th day, 15th day, 24th day, and 30th day of continuous operation, the concentration of sulfate ions in the treated effluent is measured to evaluate the sustained-release effect of the filler.

[0129] Through the tests, the results of the denitrification effect experiment are as follows:

[0130]

[0131] Through the tests, the results of the sustained-release effect experiment are as follows:

[0132]

[0133] According to the above results, it can be known that the autotrophic denitrification treatment process, its system and packing of the present invention can keep the concentration of sulfur source relatively stable during the denitrification treatment process, maintain a stable denitrification effect, and achieve a good nitrogen removal effect.

[0134] According to the results of Example 4 and Comparative Example 1, for the sulfur autotrophic denitrification packing without the slow-release agent, in the effluent after denitrification treatment, the concentration of sulfate ions fluctuates greatly, the overall nitrogen removal effect is poor, and the stability of the denitrification effect is poor. There is an obvious peak value of nitrate nitrogen removal rate on the 15th day of operation.

[0135] According to the results of Example 4 and Comparative Examples 2-4, 5, 1, compared with Comparative Example 1 without the slow-release agent, in Comparative Example 5 where tungsten disulfide treated with an intercalating agent is added instead of the polymer, in the effluent after denitrification treatment, the nitrate nitrogen removal rate is higher and the concentration fluctuation of sulfate ions is slightly smaller. This shows that the tungsten disulfide provides more attachment sites for denitrifying microorganisms, can improve the nitrogen removal efficiency, and can also weaken the concentration fluctuation of sulfate ions to a certain extent. However, there are still obvious differences between Comparative Example 5 and Comparative Examples 2-4. The slow-release effect of the polymer can significantly weaken the concentration fluctuation of sulfate ions and improve the nitrate nitrogen removal rate, indicating that it can play a certain regulatory role in the release of sulfur source. In particular, when the polymer is polycaprolactone, polyvinyl alcohol, or aldehyde-modified dextran, the formed composite material has a good slow-release effect, the sulfur source concentration is relatively stable, in the effluent after denitrification treatment, the concentration fluctuation of sulfate ions is small, and the nitrate nitrogen removal rate is high.

[0136] According to the results of Example 4, 6 and Comparative Examples 6-8, compared with tungsten disulfide without intercalating agent treatment, the composite material formed by tungsten disulfide treated with an intercalating agent can form a more regular cross-linked structure between layers, has a better slow-release effect, and also has a better nitrate nitrogen removal effect. In particular, when the intercalating agent is dodecyltrimethylammonium chloride or tripropylmethylammonium chloride, the mutual cooperation of the long-chain and short-chain structures forms a better interlayer structure of the composite material, and the obtained packing has better comprehensive performance. When the intercalating agent is a mixture of dodecyltrimethylammonium chloride, tripropylmethylammonium chloride, and (2-mercaptoethyl)trimethylammonium chloride in a weight ratio of 3:1:0.8, the stability of the slow-release effect and the nitrate nitrogen removal effect can be further improved. This may be due to the introduction of (2-mercaptoethyl)trimethylammonium chloride, which is more conducive to the formation of a cross-linked structure of the polymer between the layers of tungsten disulfide, thereby further improving the slow-release effect.

[0137] As is known by common technical knowledge, the present invention can be implemented by other embodiments that do not depart from its spiritual essence or essential features. Therefore, the above-disclosed embodiments are illustrative in all respects and not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

Claims

1. A sulfur autotrophic denitrification filler, characterized in that It comprises raw materials in the following parts by weight: 80 - 90 parts of sulfur, 0 - 5 parts of alumina, 5 - 10 parts of pH buffer, 20 - 30 parts of quartz stone, 1 - 30 parts of slow-release agent, 1 - 5 parts of binder; Among them, the slow-release agent is a composite material formed by tungsten disulfide treated with an intercalating agent and a polymer, and the polymer includes polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran; The slow-release agent is obtained by the following method: adding tungsten disulfide and an intercalating agent into water, mixing evenly to obtain tungsten disulfide treated with the intercalating agent, and then adding a polymer thereto, followed by filtration, washing, and drying after the reaction; The intercalating agent is a mixture of dodecyltrimethylammonium chloride, tripropylmethylammonium chloride, and (2-mercaptoethyl)trimethylammonium chloride in a weight ratio of 3:1:0.8; the mass ratio of tungsten disulfide, intercalating agent, and polymer is 1:(0.01 - 0.1):(2 - 6); It is obtained by the following method: (1) Take sulfur, alumina, pH buffer, quartz stone, slow-release agent, and binder, mix evenly to obtain a mixed raw material; (2) Add water to the mixed raw material in step (1) to obtain a mixed slurry; (3) Granulate and dry the mixed slurry obtained in step (2) to obtain a sulfur autotrophic denitrification filler.

2. The sulfur autotrophic denitrification filler according to claim 1, wherein The slow-release agent is specifically obtained by the following method: adding tungsten disulfide and an intercalating agent into water, ultrasonic vibrating for 30 - 60 min to obtain tungsten disulfide treated with the intercalating agent, then adding a polymer and sulfuric acid thereto, stirring and reacting at 60 - 80 °C for 2 - 10 h, and then performing filtration, washing, and drying; 3. The sulfur autotrophic denitrification filler according to claim 2, characterized in that, The polymer is a mixture of polycaprolactone, polyvinyl alcohol, and aldehyde-modified dextran in a mass ratio of 1:(1 - 10):(0.5 - 3.0); 4. The sulfur autotrophic denitrification filler according to claim 3, characterized in that, The concentration of tungsten disulfide in water is 5 - 10 g / ml.

5. The sulfur autotrophic denitrification filler according to claim 4, wherein The mass ratio of sulfuric acid to the polymer is (0.2 - 1):

100.

6. The sulfur autotrophic denitrification filler according to claim 1, wherein, In step (2), the weight ratio of the mixed raw material to water is 1:(0.2 - 5).

7. The sulfur autotrophic denitrification filler according to claim 1, wherein In step (3), the particle size of the granulation is 5 - 8 mm; In step (3), the drying temperature is 40 - 60 °C and the time is 2 - 3 h.

8. The sulfur autotrophic denitrification filler according to claim 1, characterized in that, The pH buffer is one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, and potassium hydroxide; The binder is one or more of SBS and SBR.

9. An autotrophic denitrification process for sewage treatment, characterized in that, It includes the following steps: allowing the sewage to be treated to enter a sulfur autotrophic denitrification filter, controlling the empty bed residence time to be 1 - 3 h and the average filtration rate to be 0.5 - 5 m / h, and performing denitrification treatment using the sulfur autotrophic denitrification filler described in any one of claims 1 - 8 loaded with denitrifying bacteria.

10. An autotrophic denitrification sewage treatment system, characterized in that, It at least includes a sulfur autotrophic denitrification filter; the bottom of the sulfur autotrophic denitrification filter is provided with a water inlet (11), the top is provided with a water outlet (12), and inside, there are successively arranged a water distribution layer (13), a support layer (14), a filler layer (15), and a clear water layer (16) from bottom to top; The filler layer (15) is filled with the sulfur autotrophic denitrification filler described in any one of claims 1 - 8.

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