A self-trophic denitrification composite packing material, its preparation method and application

Abstract

This invention discloses an autotrophic denitrification composite packing material, its preparation method, and its application, belonging to the field of wastewater denitrification technology. The composite packing material disclosed in this invention comprises 40%-70% sulfur, 2%-20% pyrite, 2%-20% siderite, 10%-50% limestone, 3%-20% maifanite, and 1%-3% binder. Its preparation method is as follows: S1. Batching; S2. Raw material crushing; S3. After the crushed sulfur, pyrite, siderite, limestone, and maifanite are mixed evenly, the binder is added, and the mixture is thoroughly mixed to obtain a thickened substance; S4. Granulation. The prepared round granular autotrophic denitrification composite packing material can be widely used in wastewater treatment, featuring high autotrophic denitrification efficiency and strong resistance to shock loads, and can provide a suitable acid-base environment for the growth and reproduction of autotrophic denitrifying bacteria.

Description

Technical Field

[0001] This invention belongs to the field of wastewater denitrification treatment technology, specifically relating to an autotrophic denitrification composite packing material, its preparation method, and its application. Background Technology

[0002] Autotrophic denitrification technology can remove nitrate nitrogen from wastewater without adding a carbon source, reducing the total nitrogen content of the effluent. Furthermore, autotrophic denitrification has advantages such as low sludge production and low backwashing frequency. While single-sulfur autotrophic denitrification can remove nitrate nitrogen, the hydrogen production during denitrification continuously lowers the pH of the water, leading to excessively low pH levels that fail to meet effluent pH discharge standards and hindering continuous nitrogen removal by autotrophic denitrifying bacteria. In addition, single-sulfur autotrophic denitrification has poor shock resistance; fluctuations in influent or prolonged exposure of the packing material to air can easily cause system collapse, resulting in a significant reduction in denitrification capacity.

[0003] Therefore, there is an urgent need to develop a self-trophic denitrification composite packing material to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide an autotrophic denitrification composite packing material, its preparation method, and its application, so as to solve the problems of low autotrophic denitrification efficiency and poor resistance to shock loads in the prior art, and to provide a suitable acid-base environment for the growth and reproduction of autotrophic denitrifying bacteria.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides an autotrophic denitrification composite packing material comprising the following raw materials by mass percentage: 40%-70% sulfur, 2%-20% pyrite, 2%-20% siderite, 10%-50% limestone, 3%-20% maifanite, and 1%-3% binder.

[0007] Furthermore, the purity of the sulfur is not less than 95%.

[0008] Furthermore, the adhesive is composed of sodium silicate, polyvinyl alcohol, and epoxy resin in a mass ratio of 1:0.5:0.3.

[0009] A second aspect of the present invention provides a method for preparing an autotrophic denitrification composite packing material, comprising the following steps:

[0010] S1. Weigh each raw material according to the above mass percentages;

[0011] S2. Crush sulfur to 50-150 mesh, and crush pyrite, siderite, limestone, and maifanite to 100-200 mesh;

[0012] S3. After the crushed sulfur, pyrite, siderite, limestone and maifanite are mixed evenly, a binder is added and the mixture is thoroughly mixed to obtain a thickened substance.

[0013] S4. The thickened material is granulated to obtain round granular self-trophic denitrification composite filler.

[0014] Furthermore, in step S4, the granulation drying temperature is 30℃-70℃, and the drying time is 6-12h.

[0015] Furthermore, the particle size of the autotrophic denitrification composite packing in S4 is 1-6 mm.

[0016] A third aspect of the present invention provides the application of the aforementioned self-trophic denitrification composite packing material in wastewater treatment, comprising the following steps:

[0017] Step 1. Enrichment and acclimatization of autotrophic denitrifying bacteria: Take activated sludge from the anaerobic tank of the wastewater treatment plant for cultivation and acclimatization. Inoculate the anaerobic sludge into 250mL Erlenmeyer flasks. The culture medium contains NO3. - -N 120mg / L, PO4 3- The autotrophic sludge acclimation was completed when the nitrate nitrogen concentration in the conical flask was less than 15 mg / L, the concentration of elemental sulfur was 2000 mg / L, the culture temperature was 30℃, and the shaking speed was 30 rpm.

[0018] Step 2. Operation of the autotrophic denitrification composite packing system: Load the composite packing into the column reactor to a height of 38 cm, below the effluent outlet; inoculate the acclimated sludge into the column reactor, using secondary treated wastewater as the influent to the autotrophic denitrification reactor, setting the initial retention time to 3 hours, and running for 1-3 days (d) until the effluent nitrate nitrogen stabilizes, gradually reducing the retention time; control the influent NO3... - -N concentration was measured under each condition for 16 days, 16 days, and 22 days, for a total of 54 days. Every 2 days, data such as nitrate nitrogen and pH were measured in the system effluent, and the denitrification performance parameters were recorded.

[0019] The beneficial effects of this invention are:

[0020] 1. This invention provides an autotrophic denitrification composite packing and its preparation method. The main components of the composite packing are sulfur and iron ore, with the addition of a small amount of alkali donor and other trace elements. It has a high denitrification capacity, strong resistance to shock loads, and can stably maintain a suitable acid-base environment for the growth and reproduction of autotrophic denitrifying bacteria, thus meeting the requirements for large-scale application in wastewater treatment.

[0021] 2. Siderite in the packing material acts as an autotrophic denitrification electron donor, which can reduce the production of sulfate ions, and its denitrification does not produce H₂. +Simultaneously, it can neutralize the acid produced by sulfur autotrophic denitrification, maintaining a stable pH environment in the packing material during denitrification and ensuring a high denitrification rate. Maifan stone provides trace elements needed for microbial growth, promoting the growth and reproduction of denitrifying bacteria. The presence of pyrite and siderite can cultivate iron autotrophic denitrifying bacteria, increasing the abundance of microbial species in the system, increasing system stability, and improving shock resistance.

[0022] 3. The composite packing material prepared by this invention has a large specific surface area, which facilitates the growth and reproduction of microorganisms and rapid denitrification. It also has high particle strength and is resistant to backwashing friction. The particle size is normally distributed, which can trap suspended solids in the water and reduce the suspended solids (SS) content in the effluent. Attached Figure Description

[0023] The invention will now be further described with reference to the accompanying drawings.

[0024] Figure 1 This is a line graph showing the changes in nitrate nitrogen, pH, and nitrate nitrogen removal rate in the influent and effluent over operating time in Example 5 of this invention.

[0025] Figure 2 This is a line graph showing the changes in nitrate nitrogen, pH, and nitrate nitrogen removal rate in the influent and effluent over operating time in Example 6 of this invention.

[0026] Figure 3 This is a line graph showing the changes in nitrate nitrogen, pH, and nitrate nitrogen removal rate in the influent and effluent over operating time in Example 7 of this invention. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for preparing an autotrophic denitrification composite packing material includes the following steps:

[0030] S1. Weigh each raw material according to the following mass percentages: 40%-70% sulfur (purity not less than 95%), 2%-20% pyrite, 2%-20% siderite, 10%-50% limestone, 3%-20% maifanite, and 1%-3% binder. The binder is a mixture of sodium silicate, polyvinyl alcohol, and epoxy resin in a mass ratio of 1:0.5:0.3.

[0031] S2. Crush the sulfur to 50-150 mesh, and crush the pyrite, siderite, limestone, and maifanite to 100-200 mesh respectively;

[0032] S3. After mixing the crushed sulfur, pyrite, siderite, limestone and maifanite evenly, add the binder and mix thoroughly to obtain a thickened substance.

[0033] S4. The mixed thickened material is fed into a granulator for granulation, and then dried at a low temperature of 30-70℃ to obtain round filler particles. The drying time is 6-12 hours, forming self-trophic denitrification composite filler particles with a particle size of 1-6 mm.

[0034] Example 2

[0035] A method for preparing an autotrophic denitrification composite packing material includes the following steps:

[0036] S1. Weigh each raw material according to the following mass percentages: 53% sulfur (purity 96%), 14% pyrite, 14% siderite, 12% limestone, 5% maifanite, and 2% binder. The binder is a mixture of sodium silicate, polyvinyl alcohol, and epoxy resin in a mass ratio of 1:0.5:0.3.

[0037] S2. Crush the sulfur to 130 mesh, and crush the pyrite, siderite, limestone, and maifanite to 180 mesh respectively;

[0038] S3. After mixing the crushed sulfur, pyrite, siderite, limestone and maifanite evenly, add the binder and mix thoroughly to obtain a thickened substance.

[0039] S4. The mixed thickened material is fed into a granulator for granulation, and then dried at a low temperature of 50℃ to obtain round filler particles. The drying time is 9 hours, forming self-trophic denitrification composite filler particles with a particle size range of 1-6 mm.

[0040] Example 3

[0041] A method for preparing an autotrophic denitrification composite packing material includes the following steps:

[0042] S1. Weigh each raw material according to the following mass percentages: 40% sulfur (95% purity), 12% pyrite, 7% siderite, 25% limestone, 15% maifanite, and 1% binder. The binder is a mixture of sodium silicate, polyvinyl alcohol, and epoxy resin in a mass ratio of 1:0.5:0.3.

[0043] S2. Crush the sulfur to 100 mesh, and crush the pyrite, siderite, limestone, and maifanite to 150 mesh respectively.

[0044] S3. After mixing the crushed sulfur, pyrite, siderite, limestone and maifanite evenly, add the binder and mix thoroughly to obtain a thickened substance.

[0045] S4. The mixed thickened material is fed into a granulator for granulation, and then dried at a low temperature of 35℃ to obtain round filler particles. The drying time is 12h, forming self-trophic denitrification composite filler particles with a particle size range of 1-6mm.

[0046] Example 4

[0047] A method for preparing an autotrophic denitrification composite packing material includes the following steps:

[0048] S1. Weigh each raw material according to the following mass percentages: 60% sulfur (98% purity), 8% pyrite, 8% siderite, 11% limestone, 10% maifanite, and 3% binder. The binder is a mixture of sodium silicate, polyvinyl alcohol, and epoxy resin in a mass ratio of 1:0.5:0.3.

[0049] S2. Crush the sulfur to 60 mesh, and crush the pyrite, siderite, limestone, and maifanite to 100 mesh respectively;

[0050] S3. After mixing the crushed sulfur, pyrite, siderite, limestone and maifanite evenly, add the binder and mix thoroughly to obtain a thickened substance.

[0051] S4. The mixed thickened material is fed into a granulator for granulation, and then dried at a low temperature of 65℃ to obtain round filler particles. The drying time is 6 hours, forming self-trophic denitrification composite filler particles with a particle size range of 1-6 mm.

[0052] Example 5

[0053] Application of an autotrophic denitrification composite packing material in municipal wastewater treatment

[0054] (1) Enrichment and domestication of autotrophic denitrifying bacteria

[0055] Activated sludge from the anaerobic tank of a wastewater treatment plant was cultured and acclimated. The anaerobic sludge was inoculated into 250 mL Erlenmeyer flasks, and the culture medium contained NO3. - -N 120mg / L, PO4 3- The concentration of nitrate nitrogen in the conical flask was 150 mg / L, and the concentration of elemental sulfur was 2000 mg / bottle. The culture temperature was 30℃, and the shaking speed was 30 rpm. The autotrophic sludge acclimation was completed when the concentration of nitrate nitrogen in the conical flask was less than 15 mg / L (removal rate was higher than 85%).

[0056] (2) Operation of the denitrification system of the autotrophic denitrification composite packing

[0057] The composite packing material prepared in Example 2 of this invention is loaded into a column reactor. The packing material has a particle size range of 1-6 mm and a loading height of 38 cm, which is lower than the outlet.

[0058] The acclimated sludge was inoculated into a column reactor. The secondary treated effluent from the wastewater treatment plant was used as the influent to the autotrophic denitrification reactor. The initial retention time was set to 3 hours. After 1-3 days of operation, the nitrate nitrogen in the effluent stabilized, and the retention time was gradually reduced to 1 hour.

[0059] Peristaltic pumps were used to pump the secondary treated effluent from the wastewater treatment plant. The retention time was set to 1 hour, and the system was operated continuously for 16 days. Every 2 days, data such as nitrate nitrogen and pH of the system effluent were measured, and the denitrification performance parameters were recorded.

[0060] The self-supporting denitrification system operates stably, and effluent data is monitored and recorded in a timely manner. Line graphs showing the changes in effluent nitrate nitrogen, pH, and other data over operating time are shown below. Figure 1 When NO3 enters the water - With NO3- concentrations ranging from 8 to 10 mg / L and a retention time of 1 hour, the effluent pH can be stabilized between 6.9 and 7.17, the effluent nitrate nitrogen concentration is 0 mg / L, the nitrate nitrogen removal rate is 100%, and the maximum nitrate nitrogen removal load is 0.29 kg NO3. - -N / m 3 / d, the composite packing has good denitrification performance.

[0061] Example 6

[0062] Application of an autotrophic denitrification composite packing material in municipal wastewater treatment

[0063] (1) Enrichment and domestication of autotrophic denitrifying bacteria

[0064] Activated sludge from the anaerobic tank of a wastewater treatment plant was cultured and acclimated. The anaerobic sludge was inoculated into 250 mL Erlenmeyer flasks, and the culture medium contained NO3. - -N 120mg / L, PO4 3- The concentration of nitrate nitrogen in the conical flask was 150 mg / L, and the concentration of elemental sulfur was 2000 mg / bottle. The culture temperature was 30℃, and the shaking speed was 30 rpm. The autotrophic sludge acclimation was completed when the concentration of nitrate nitrogen in the conical flask was less than 15 mg / L (removal rate was higher than 85%).

[0065] (2) Operation of the denitrification system of the autotrophic denitrification composite packing

[0066] The composite packing material prepared in Example 2 of this invention is loaded into a column reactor. The packing material has a particle size range of 1-6 mm and a loading height of 38 cm, which is lower than the outlet.

[0067] The acclimated sludge was inoculated into a column reactor, and the secondary treated effluent from the wastewater treatment plant was used as the influent to the autotrophic denitrification reactor. The initial retention time was set to 3 hours. After 1-3 days of operation, the nitrate nitrogen in the effluent stabilized, and the retention time was gradually reduced to 0.5 hours.

[0068] Peristaltic pumps were used to pump the secondary treated effluent from the wastewater treatment plant. The retention time was set to 0.5 hours, and the system was operated continuously for 16 days. Every two days, data such as nitrate nitrogen and pH of the effluent were measured, and the denitrification performance parameters were recorded.

[0069] The self-supporting denitrification system operates stably, and effluent data is monitored and recorded in a timely manner. Line graphs showing the changes in effluent nitrate nitrogen, pH, and other data over operating time are shown below. Figure 2 When NO3 enters the water - When the NO3- concentration is in the range of 8.2-10.3 mg / L and the retention time is 0.5 h, the effluent pH can be stabilized between 6.82 and 7.44, the effluent nitrate nitrogen concentration is in the range of 0-0.3 mg / L, the nitrate nitrogen removal rate is in the range of 96.3-100%, and the maximum nitrate nitrogen removal load is 0.50 kg NO3. - -N / m 3 / d. Compared to Example 5, the nitrate nitrogen removal rate is basically the same, both maintaining a high denitrification efficiency. The composite packing has good denitrification performance, but the residence time is shortened from 1h to 0.5h, which has engineering application value.

[0070] Example 7

[0071] Application of an autotrophic denitrification composite packing material in municipal wastewater treatment

[0072] (1) Enrichment and domestication of autotrophic denitrifying bacteria

[0073] Activated sludge from the anaerobic tank of a wastewater treatment plant was cultured and acclimated. The anaerobic sludge was inoculated into 250 mL Erlenmeyer flasks, and the culture medium contained NO3. - -N 120mg / L, PO4 3- The concentration of nitrate nitrogen in the conical flask was 150 mg / L, and the concentration of elemental sulfur was 2000 mg / bottle. The culture temperature was 30℃, and the shaking speed was 30 rpm. The autotrophic sludge acclimation was completed when the concentration of nitrate nitrogen in the conical flask was less than 15 mg / L (removal rate was higher than 85%).

[0074] (2) Operation of the denitrification system of the autotrophic denitrification composite packing

[0075] The composite packing material prepared in Example 2 of this invention is loaded into a column reactor. The packing material has a particle size range of 1-6 mm and a loading height of 38 cm, which is lower than the outlet.

[0076] KNO3 solution was artificially added to the secondary treated effluent of a municipal wastewater treatment plant used in the laboratory to control the nitrate nitrogen concentration in the influent to the range of 15.1-18.3 mg / L. The pH was not artificially adjusted and was set at 6.4-7.11. The retention time was set to 0.5 h. After 22 days of stable operation, the effluent from the column reactor was sampled every 2 days, filtered through a 0.45 μm filter membrane, and the nitrate nitrogen and pH data were measured.

[0077] The self-supporting denitrification system operates stably, and effluent data is monitored and recorded in a timely manner. Line graphs showing the changes in effluent nitrate nitrogen, pH, and other data over operating time are shown below. Figure 3 When NO3 enters the water - When the nitrogen concentration is in the range of 15.1-15.9 mg / L and the retention time is 0.5 h, the nitrate nitrogen removal rate is 94.8%-100%, and the effluent nitrate nitrogen concentration is 0-0.7 mg / L. The packing effectively neutralizes the H2 produced by autotrophic denitrification. + The pH value is stable between 6.42 and 6.74.

[0078] When NO3 enters the water - When NO3- concentration is in the range of 17.5-18.3 mg / L and retention time is 0.5 h, the nitrate nitrogen removal rate is 83.6-98.3%, the effluent nitrate nitrogen concentration is 0.3-3 mg / L, and the maximum nitrate nitrogen removal load is 0.87 kg NO3. - -N / m 3 / d. During this stage, the influent pH decreased to 6.4, while the effluent pH remained stable above 6.1. The results indicate that even with increased influent nitrate nitrogen concentration and a controlled retention time of 0.5 h, the packing material still exhibits excellent denitrification performance.

[0079] Example 8

[0080] The autotrophic denitrification composite packing material prepared in Example 3 was applied to municipal wastewater treatment. The application process was the same as in Examples 5 and 6, and its denitrification performance parameters are shown in Table 1.

[0081] Example 9

[0082] The autotrophic denitrification composite packing material prepared in Example 4 was applied to municipal wastewater treatment. The application process was the same as in Examples 5 and 6, and its denitrification performance parameters are shown in Table 1.

[0083] Table 1

[0084]

[0085] As shown in Table 1, the composite packings prepared in Examples 3 and 4 also possess good denitrification performance and engineering application value.

[0086] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0087] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A self-trophic denitrification composite packing material, characterized in that, The raw materials include the following percentages by weight: 40%-70% sulfur, 2%-20% pyrite, 2%-20% siderite, 10%-50% limestone, 3%-20% maifanite, and 1%-3% binder. The adhesive is composed of sodium silicate, polyvinyl alcohol, and epoxy resin in a mass ratio of 1:0.5:0.

3. The autotrophic denitrification composite packing is prepared through the following steps: S1. Weigh each raw material according to the above mass percentages; S2. Crush sulfur to 50-150 mesh, and crush pyrite, siderite, limestone, and maifanite to 100-200 mesh; S3. After the crushed sulfur, pyrite, siderite, limestone and maifanite are mixed evenly, a binder is added and the mixture is thoroughly mixed to obtain a thickened substance. S4. Granulate the thickened material to obtain round granular self-trophic denitrification composite filler; In step S4, the granulation drying temperature is 30℃-70℃, and the drying time is 6-12h.

2. The self-trophic denitrification composite packing material according to claim 1, characterized in that, The sulfur has a purity of not less than 95%.

3. The self-trophic denitrification composite packing material according to claim 1, characterized in that, The particle size of the autotrophic denitrification composite filler in S4 is 1-6 mm.

4. A wastewater treatment method using the autotrophic denitrification composite packing material according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1. Enrichment and acclimatization of autotrophic denitrifying bacteria: Take activated sludge from the anaerobic tank of the wastewater treatment plant for cultivation and acclimatization. Inoculate the anaerobic sludge into 250mL Erlenmeyer flasks. The culture medium contains NO3. - -N 120mg / L, PO4 3- The autotrophic sludge acclimation was completed when the nitrate nitrogen concentration in the conical flask was less than 15 mg / L, the concentration of elemental sulfur was 2000 mg / L, the culture temperature was 30℃, and the shaking speed was 30 rpm. Step 2. Operation of the autotrophic denitrification composite packing system: Load the composite packing into the column reactor to a height of 38 cm, below the effluent outlet; inoculate the acclimated sludge into the column reactor; use secondary treated wastewater from the wastewater treatment plant as the influent to the autotrophic denitrification reactor; set the initial retention time to 3 hours; after 1-3 days of operation until the effluent nitrate nitrogen stabilizes, gradually reduce the retention time; control the influent NO3... - -N concentration, continuous operation, and data collection of system effluent every 2 days to record denitrification performance parameters.

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