Mixed nutritional denitrifying nitrogen removal electron donor and construction method thereof

Abstract

The invention provides a mixed nutrition type denitrification nitrogen removal electron donor and a construction method, and relates to the field of biological denitrification, and the construction method comprises the following steps: adopting a simulation reactor to simulate a sewage anoxic tank, taking a liquid sulfur source as an electron donor to culture denitrifying bacteria, and completing domestication of sulfur autotrophic denitrifying bacteria; the method comprises the following steps: taking inflow water of an anoxic tank of a sewage plant as a water source, controlling hydraulic retention time to be consistent with that of the anoxic tank, and adding a carbon source or an alkaline buffering agent to adjust a denitrification nitrogen removal load and a pH value to a preset range; the agent proportion is determined according to the fed liquid sulfur source, the carbon source or the alkaline buffering agent, the proportion is used for preparing a mixed nutritional type denitrification nitrogen removal electron donor, and the mixed nutritional type denitrification nitrogen removal electron donor is used as a nitrogen removal electron donor of a denitrification system of the sewage treatment anoxic tank. The mixed denitrification nitrogen removal electron donor aiming at the sewage quality can be obtained, and the consumption of an organic carbon source is reduced.

Description

Technical Field

[0001] The present application relates to the field of biological denitrification, and in particular to a mixed nutrition type denitrification electron donor and a construction method thereof. Background Art

[0002] Denitrification is a microbial-mediated biochemical process that occurs primarily in anoxic environments and involves the conversion of nitrate (NO3 - ) and nitrite (NO2 - ) is reduced to gaseous nitrogen compounds (such as N2, N2O), and finally the active nitrogen in the water or soil is released into the atmosphere in the form of nitrogen gas. In sewage treatment, by designing and operating anaerobic or anoxic treatment units, the growth of denitrifying bacteria and denitrification reactions are promoted to achieve effective removal of nitrogen in sewage and meet emission standards or resource recovery requirements. The denitrification process is of great value to the nitrogen balance of the ecosystem, sewage treatment and environmental protection.

[0003] Traditional heterotrophic denitrification processes rely on organic carbon sources. For sewage treatment plants with insufficient influent carbon sources, external organic carbon sources such as glucose and sodium acetate need to be added. The operating costs are high and there may be a risk of carbon source penetration.

[0004] In view of the above-mentioned defects, there is an urgent need for a mixed trophic denitrification electron donor and a construction method, which can obtain a mixed denitrification electron donor for sewage water quality and reduce the consumption of organic carbon sources. Summary of the invention

[0005] The present application provides a mixed trophic denitrification electron donor and a construction method, which can obtain a mixed denitrification electron donor for sewage water quality and reduce the consumption of organic carbon sources.

[0006] In a first aspect, the present application provides a method for constructing a mixed-trophic denitrification electron donor, comprising:

[0007] A simulated reactor was used to simulate the sewage anoxic pool and liquid sulfur source was used as an electron donor to cultivate denitrifying bacteria to complete the domestication of sulfur autotrophic denitrifying bacteria.

[0008] The influent of the anoxic tank of the sewage treatment plant is used as the water source, and the hydraulic retention time is controlled to be consistent with that of the anoxic tank. The denitrification load and pH value are adjusted to the preset range by adding carbon source or alkaline buffer;

[0009] The reagent ratio is determined according to the liquid sulfur source, the carbon source or the alkaline buffer, and the ratio is used to prepare a mixed nutritional denitrification electron donor, which is used as a denitrification electron donor in the denitrification system of the sewage treatment anoxic tank.

[0010] In a possible design, the adjustment of the denitrification load and pH value to a preset range by adding a carbon source or an alkaline buffer comprises:

[0011] Obtaining the denitrification load in the denitrification process according to the nitrate concentration;

[0012] Determining whether the denitrification load is less than the preset load value;

[0013] If it is less than the preset load value, adding a carbon source to the simulated reactor until the denitrification load is not less than the preset load value;

[0014] Determine whether the pH value is not less than a preset pH value; if it is less than the preset pH value, add an alkaline buffer until the pH value is not less than the preset pH value.

[0015] In a possible design, the simulated reactor is used to simulate the sewage anoxic pool to cultivate denitrifying bacteria with a liquid sulfur source as an electron donor to complete the domestication of sulfur autotrophic denitrifying bacteria, including:

[0016] Inoculating sludge from anoxic tanks of a sewage treatment plant in a simulated reactor, using influent from the anoxic tanks of the sewage treatment plant as a water source; determining the amount of the liquid sulfur source to be added according to the concentration of nitrate in the simulated reactor;

[0017] The liquid sulfur source is added to the simulated reactor according to the added amount; the nitrate concentration in the simulated reactor is monitored, and the denitrification rate is obtained according to the nitrate concentration. If the denitrification rate tends to be stable, it is determined that the sulfur autotrophic denitrifying bacteria have been successfully domesticated.

[0018] In a possible design, determining the amount of the liquid sulfur source to be added according to the concentration of nitrate includes:

[0019] Determine the amount of sulfur required based on a nitrogen-sulfur ratio of 1:1.1;

[0020] The amount of the liquid sulfur source to be added is determined according to the amount of sulfur element and the ratio of the amount of sulfur element to the amount of the liquid sulfur source.

[0021] In a possible design, obtaining the denitrification load in the denitrification process according to the nitrate concentration includes:

[0022] Obtaining the nitrate concentration before and after a preset period, and obtaining the denitrification rate of the period according to the ratio of the change in the nitrate concentration to the corresponding time interval;

[0023] The denitrification load is obtained according to the denitrification rate.

[0024] In one possible design, the liquid sulfur source is sodium sulfide or liquid sodium thiosulfate.

[0025] In a possible design, the preset pH value is set within the range of 6.5 to 8.0.

[0026] In one possible design, the alkaline buffer is sodium carbonate or sodium bicarbonate.

[0027] In a second aspect, the present application provides a mixed nutritional denitrification electron donor, comprising a mixture of one or more of a liquid sulfur source, a carbon source and an alkaline buffer in a preset ratio, wherein the preset ratio is a ratio obtained according to the construction method of the above-mentioned mixed nutritional denitrification electron donor.

[0028] In a third aspect, the present application provides an anoxic tank denitrification system, comprising the above-mentioned mixed nutritional denitrification electron donor.

[0029] The present application provides a mixed-trophic denitrification electron donor and construction method, including: using a simulated reactor to simulate a sewage anoxic tank to cultivate denitrifying bacteria with a liquid sulfur source as an electron donor to complete the domestication of sulfur-autotrophic denitrifying bacteria; using the influent of the sewage treatment plant anoxic tank as the water source, controlling the hydraulic retention time to be consistent with the anoxic tank, and adjusting the denitrification load and pH value to a preset range by adding a carbon source or an alkaline buffer; determining the reagent ratio based on the added liquid sulfur source, the carbon source or the alkaline buffer, and the ratio is used to prepare a mixed-trophic denitrification electron donor, and the mixed-trophic denitrification electron donor is used as a denitrification electron donor for the denitrification system of the sewage treatment anoxic tank. The following technical effects are achieved:

[0030] The method provided in the present application can simulate the water quality of the anoxic tank of a sewage treatment plant and obtain a mixed trophic denitrification electron donor of a certain proportion. The electron donor is highly compatible with the sewage treatment plant, has a high electron utilization rate, and a fast reaction rate. It can reduce the consumption of carbon sources in the anoxic tank and avoid the risk of system instability caused by changes in the pH value of the denitrification system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram of a method for constructing a mixed nutrition type denitrification electron donor provided in the embodiment of the present application Figure 1 ;

[0033] Figure 2 A schematic diagram of a method for constructing a mixed nutrition type denitrification electron donor provided in the embodiment of the present application Figure 2 .

[0034] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0035] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims, rather than all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] It should be noted that in the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0037] It should be noted that the “at…” in the embodiments of the present application may be the instant when a certain situation occurs, or may be a period of time after the occurrence of a certain situation, and the embodiments of the present application do not specifically limit this.

[0038] First, the terms in this application are explained:

[0039] Denitrification process: The denitrification process is a series of reduction reactions carried out by specific microorganisms under anaerobic conditions, which convert nitrates and nitrites into gaseous nitrogen compounds. It can be used in anoxic tank denitrification systems and is of great value to the nitrogen balance of the ecosystem, sewage treatment and environmental protection.

[0040] Carbon source: refers to substances that provide carbon elements. These substances are usually rich in carbon compounds and can be absorbed by organisms and converted into organic substances required by themselves. In the denitrification process of sewage treatment, organic carbon sources are needed as electron donors to remove nitrogen from sewage. Organic carbon sources: methanol, sodium acetate, glucose, etc. In practical applications, when selecting carbon sources, factors such as bioavailability, economy, environmental impact, and convenience of addition need to be considered to ensure the efficiency, stability, and economy of the sewage treatment process.

[0041] Sulfur autotrophic denitrifiers: are a type of microorganism that can use sulfur compounds as electron donors to carry out denitrification reactions (reducing nitrates to nitrogen gas) under anaerobic or microaerobic conditions. Sulfur autotrophic denitrification deep denitrification process is usually regarded as part of the tertiary biological treatment unit, because it mainly targets the nitrates (NO 3- -N), for further denitrification treatment to meet more stringent nitrogen emission standards or water resource reuse requirements.

[0042] Secondary biological treatment unit: The secondary biological treatment unit is a core link in the sewage treatment process. Its main goal is to further remove organic matter, suspended solids and some nutrients such as nitrogen and phosphorus that remain in the sewage after primary treatment (such as screens, grit chambers, primary sedimentation tanks, etc.). Secondary biological treatment mainly relies on the biochemical action of microorganisms to degrade organic pollutants through the metabolism of microorganisms and convert them into harmless or low-toxic substances, such as carbon dioxide, water, nitrogen, etc.

[0043] Tertiary biological treatment unit: also known as deep biological treatment or advanced biological treatment, is a biological treatment link after primary and secondary biological treatment to further remove low-concentration organic matter, nitrogen, phosphorus and other specific pollutants that remain in the sewage after the first two stages of treatment. The goal of tertiary biological treatment is to meet more stringent discharge standards, improve the quality of recycled water or achieve efficient removal of specific pollutants.

[0044] In the prior art, denitrification processes include autotrophic denitrification processes and heterotrophic denitrification processes. The heterotrophic denitrification process is a part of the secondary biological treatment unit. The sulfur autotrophic denitrification process is currently commonly used in the tertiary biological treatment unit to further perform deep denitrification treatment on the nitrates that remain after the secondary biological treatment. The traditional heterotrophic denitrification process relies on organic carbon sources. For sewage treatment plants with insufficient influent carbon sources, it is necessary to add organic carbon sources such as glucose and sodium acetate. The operating cost is high and there may be a risk of carbon source penetration.

[0045] In view of the above technical problems, the present application provides a method for constructing a mixed nutrition type denitrification denitrification electron donor, which is used to obtain a mixed type denitrification denitrification electron donor.

[0046] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0047] Figure 1 A schematic diagram of a method for constructing a mixed nutrition type denitrification electron donor provided in the embodiment of the present application Figure 1 ;like Figure 1 As shown, the method includes:

[0048] S101, using a simulated reactor to simulate a sewage anoxic pool and using a liquid sulfur source as an electron donor to cultivate denitrifying bacteria, thereby completing the domestication of sulfur autotrophic denitrifying bacteria;

[0049] Specifically, the domestication of sulfur autotrophic denitrifying bacteria refers to the process of promoting the proliferation of such strains naturally existing in the environment and adapting them to specific environmental conditions, thereby improving their denitrification activity and treatment efficiency.

[0050] Specifically, the simulation reactor generally adopts a kettle, which can realize the functions of inlet and outlet flow rate control, environmental parameter monitoring and control, and material output during the reaction process. It is used to simulate the denitrification process of the sewage anoxic tank and meet the controllability and safety requirements of the simulation process.

[0051] S102, using the influent of the anoxic tank of the sewage treatment plant as the water source, controlling the hydraulic retention time to be consistent with that of the anoxic tank, and adjusting the denitrification load and pH value to a preset range by adding a carbon source or an alkaline buffer;

[0052] Specifically, the hydraulic retention time of the anoxic tank of a sewage treatment plant refers to the average residence time of the influent in the anoxic tank. It is calculated based on the ratio of the effective volume to the influent flow rate. It is an important parameter to measure the contact time between the fluid and the medium (such as activated sludge, filler, soil, etc.) in the treatment unit. Keeping the hydraulic retention time consistent with the anoxic tank can better simulate the denitrification process in the anoxic tank of the sewage treatment plant.

[0053] Specifically, the addition of carbon source is used to adjust the denitrification load to reach the design value. The consumption of carbon source is an alkali-producing reaction, and the consumption of autotrophic denitrifying bacteria is an acid-producing reaction. Therefore, alkaline buffer is used to adjust the pH value in the reactor to ensure that the pH value in the system is balanced and stable.

[0054] S103. Determine the reagent ratio according to the added liquid sulfur source, carbon source or alkaline buffer, and the ratio is used to prepare a mixed trophic denitrification electron donor, which is used as a denitrification electron donor in a denitrification system of anoxic tanks for sewage treatment.

[0055] Specifically, the ratio of the liquid sulfur source added in step S101, the carbon source and the alkaline buffer that may be added in step S102 is the reagent ratio in the anoxic tank of the sewage treatment plant, and the reagent mixture with the same ratio is the reagent of the dosing system in the anoxic tank of the sewage treatment plant.

[0056] The present application provides a method for constructing a mixed-trophic denitrification electron donor, which is to acclimate sulfur autotrophic denitrifying bacteria in a simulated reactor, simulate the denitrification process in an anoxic tank of a sewage treatment plant, and adjust the denitrification load and pH value to a preset range by adding a carbon source or an alkaline buffer, thereby determining the reagent ratio, and configuring the denitrification reagent according to the ratio as the denitrification electron donor of the anoxic tank of the sewage treatment plant. The following technical effects can be achieved:

[0057] The method provided in this embodiment can simulate the water quality of the anoxic tank of a sewage treatment plant and obtain a mixed trophic denitrification electron donor of a certain proportion. The electron donor is highly compatible with the sewage treatment plant, has a high electron utilization rate, a fast reaction rate, and can reduce the consumption of carbon sources in the anoxic tank.

[0058] Figure 2 A schematic diagram of a method for constructing a mixed nutrition type denitrification electron donor provided in the embodiment of the present application Figure 2 ;like Figure 2 As shown, the method includes:

[0059] S201, inoculating sludge from anoxic tank of sewage treatment plant in a simulated reactor, using influent from anoxic tank of sewage treatment plant as a water source; determining the amount of liquid sulfur source to be added according to the concentration of nitrogen in the simulated reactor;

[0060] Specifically, the liquid sulfur source is a sulfate compound, including liquid sodium thiosulfate and sodium sulfide, which can be one or more thereof.

[0061] Specifically, the amount of sulfur element required is determined according to the nitrogen-sulfur ratio of 1:1 to 1:2; and the amount of liquid sulfur source added is determined according to the amount of sulfur element and the ratio of the amount of sulfur element to the amount of liquid sulfur source.

[0062] Specifically, the reaction formula of N and S in sewage is:

[0063] NO3-+1.10S+0.40CO2+0.76H2O+0.08NH4+→0.5N2+1.10SO4 2- +1.28H + +0.08C5H7O2N

[0064] According to the above formula, the nitrogen-sulfur ratio is 1:1.11, where 1:1.1 is the ratio of the amount of nitrogen and sulfur in moles; the mass ratio of nitrogen and sulfur is 14:35, that is, if 14 mg of nitrogen needs to react, 35 mg of sulfur needs to be added.

[0065] Specifically, since the liquid sulfur source can be selected from different substances, after obtaining the amount of sulfur element substance, the addition amount of the liquid sulfur source is obtained specifically according to the proportion of sulfur in the liquid sulfur source.

[0066] S202, adding a liquid sulfur source to the simulated reactor according to the added amount; monitoring the nitrate concentration in the simulated reactor, and obtaining the denitrification rate according to the nitrate concentration. If the denitrification rate tends to be stable, it is determined that the sulfur autotrophic denitrifying bacteria have been successfully domesticated.

[0067] Specifically, a liquid sulfur source is used as an electron donor for sulfur autotrophic denitrification, and is added according to a determined addition amount. When the denitrification rate is stabilized, it is determined that the sulfur autotrophic denitrifying bacteria have been successfully domesticated.

[0068] In one embodiment, the nitrate concentration in the simulated reactor is monitored every preset period, and the denitrification rate in a preset period is obtained according to the nitrate concentration; if the difference of the denitrification rate in 2 to 3 consecutive preset periods is less than the preset difference, it is determined that the denitrification rate is stable;

[0069] As an embodiment, for the nitrate concentration before and after a preset period, the denitrification rate can be obtained according to the ratio of the change in the nitrate concentration to the corresponding time interval.

[0070] S203, using the influent of the anoxic tank of the sewage treatment plant as the water source, controlling the hydraulic retention time to be consistent with that of the anoxic tank, and obtaining the denitrification load in the denitrification process according to the nitrate concentration;

[0071] Specifically, the method for calculating a new denitrification load based on nitrate concentration includes: obtaining the nitrate concentration before and after a preset period, obtaining the denitrification rate of the period based on the ratio of the change in nitrate concentration to the corresponding time interval; and obtaining the denitrification load based on the denitrification rate.

[0072] Specifically, the denitrification rate is the amount of nitrate nitrogen removed / reaction time; denitrification load: denitrification load refers to the mass of nitrate that microorganisms can consume per unit time and unit volume, and the unit is kgN / m 3 ·d.

[0073] In one embodiment, the denitrification load can be obtained by converting the denitrification rate into units.

[0074] In another embodiment, the denitrification denitrification load can be obtained according to the mass of consumed nitrate, that is, denitrification denitrification load=mass of consumed nitrate (kg) / reaction volume (m3) / reaction time (d).

[0075] S204, determine whether the denitrification and denitrification load is less than the preset load value; if it is less than the preset load value, add carbon source to the simulation reactor until the denitrification and denitrification load is not less than the preset load value; execute S205; if it is not less than the preset load value; execute S205;

[0076] As an embodiment, when the denitrification denitrification load is less than the preset load value, one unit of carbon source is added to the simulation reactor, and the nitrate concentration is re-acquired after a preset time period to calculate a new denitrification denitrification load, and it is re-determined whether the denitrification denitrification load is less than the preset load value. If it is less, the operation of adding one unit of carbon source to the simulation reactor is returned until it is determined that the denitrification denitrification load is not less than the preset load value, and the total amount of carbon source added is recorded, and step S205 is executed;

[0077] As an example, the preset load value is generally 300-1200gNO3-N / m 3 d, which represents the mass of nitrate nitrogen removed per cubic meter per day;

[0078] Specifically, a preset time period is used to wait for the addition of the agent and ensure a sufficient reaction.

[0079] S205, determining whether the pH value is not less than a preset pH value; if it is less than the preset pH value, adding an alkaline buffer until the pH value is not less than the preset pH value, and executing S206; if it is not less than the preset pH value, executing S206;

[0080] Specifically, the method couples the acid production process of consuming sulfur autotrophic denitrifying bacteria with the alkali production process of consuming carbon sources. In order to ensure the acidity and alkalinity stability of the entire system, the pH value needs to be adjusted to neutral.

[0081] Specifically, similar to S204, the pH value is gradually adjusted by adding small doses multiple times until the pH value is not less than the preset pH value.

[0082] As some embodiments, sodium carbonate or sodium bicarbonate is used as the alkaline buffer of the present application;

[0083] Further, the preset pH value is determined to be within the range of 6.5-8.0;

[0084] Preferably, the preset pH value is 7.5.

[0085] S206. Determine the reagent ratio according to the added liquid sulfur source, carbon source or alkaline buffer, and the ratio is used to prepare a mixed trophic denitrification electron donor, which is used as a denitrification electron donor in a denitrification system of anoxic tanks for sewage treatment.

[0086] Specifically, the amount ratio or mass ratio of the liquid sulfur source, carbon source and alkaline buffer added in the method of the present application is a determined ratio;

[0087] Specifically, a liquid sulfur source, a carbon source and an alkaline buffer of the same substance are taken and mixed in a determined ratio to obtain a mixture as a mixed nutritional denitrification electron donor, and the electron donor is used in the denitrification system of the anoxic tank of the sewage treatment plant as an additive.

[0088] Specifically, depending on the characteristics of the water source, according to the above method, there may be a situation where there is no need to add a carbon source or an alkaline buffer, and the configured mixed nutritional denitrification electron donor may include one or more of a liquid sulfur source, a carbon source and an alkaline buffer.

[0089] In one embodiment, a mixed trophic denitrification electron donor obtained according to the present application is transported to the anoxic tank through a dosing system. At the initial start-up of the mixed trophic denitrification system in the anoxic tank of the sewage treatment plant, the abundance of sulfur autotrophic denitrifying bacteria in the anoxic tank may be low. At the initial stage of commissioning the mixed trophic denitrification process in the sewage treatment plant, the total nitrogen effluent concentration should be always paid attention to through the online detection system. If the total nitrogen concentration increases, the timely replenishment of the organic carbon source is started. As the startup time of the mixed trophic denitrification system increases, the abundance of sulfur autotrophic denitrifying bacteria gradually increases, and the contribution of sulfur autotrophic denitrification to denitrification increases, and the additional carbon source replenishment can be gradually reduced or even cancelled.

[0090] The method provided in the embodiment of the present application uses a simulated reactor to simulate a sewage anoxic pool to cultivate denitrifying bacteria with a liquid sulfur source as an electron donor to complete the domestication of sulfur autotrophic denitrifying bacteria; uses the influent of the sewage treatment plant anoxic pool as the water source, controls the hydraulic retention time to be consistent with the anoxic pool, and adjusts the denitrification load and pH value to a preset range by adding a carbon source or an alkaline buffer; determines the reagent ratio based on the added liquid sulfur source, carbon source or alkaline buffer, and the ratio is used to prepare a mixed nutrition type denitrification denitrification electron donor, which is used as a denitrification electron donor for the denitrification system of the sewage treatment anoxic pool. The following technical effects can be achieved:

[0091] The electron donor obtained through the embodiments of the present application is used as the denitrification electron donor of the anoxic tank. The anoxic tank denitrification system constructed by the anoxic tank has an increased abundance of sulfur autotrophic denitrifying bacteria as the system is used for a longer time, and the contribution of sulfur autotrophic denitrification to denitrification is improved, and the additional carbon source supply can be gradually reduced or even cancelled; it can replace the traditional anoxic denitrification system of a sewage treatment plant with insufficient carbon source, greatly reducing the carbon source addition cost of the sewage treatment plant.

[0092] The embodiment of the present application can advance the sulfur autotrophic denitrification deep denitrification process of the secondary biological treatment unit to the denitrification denitrification in the anoxic tank of the secondary biological treatment unit, thereby shortening the sewage treatment process and achieving low-cost deep denitrification.

[0093] The embodiment of the present application couples the acid-producing autotrophic denitrification process with the alkali-producing heterotrophic denitrification process, thereby avoiding the risk of system instability caused by pH changes in the denitrification system.

[0094] The embodiment of the present application adopts a composite electron donor composed of a liquid sulfur source and a traditional carbon source, which has the advantages of high electron utilization rate and fast reaction rate, and the formula can be adjusted flexibly without the risk of penetration.

[0095] A mixed nutritional denitrification electron donor provided in an embodiment of the present application comprises a mixture of one or more of a liquid sulfur source, a carbon source and an alkaline buffer in a preset ratio, wherein the preset ratio is obtained according to the method for constructing the mixed nutritional denitrification electron donor described above.

[0096] The principle and technical effect are similar to the method for constructing a mixed nutritional denitrification electron donor mentioned above, and will not be described in detail here.

[0097] The embodiment of the present application also provides an anoxic pond denitrification system, which uses the above-mentioned mixed nutritional denitrification denitrification electron donor as the denitrification electron donor.

[0098] The principle and technical effect are similar to the method for constructing a mixed nutritional denitrification electron donor mentioned above, and will not be described in detail here.

[0099] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required by the present application.

[0100] It should be further noted that, although the various steps in the flowchart are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowchart may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

Claims

1. A method for constructing a mixed nutritional denitrification electron donor, characterized in that: include: A simulated reactor was used to simulate the sewage anoxic pool and liquid sulfur source was used as an electron donor to cultivate denitrifying bacteria to complete the domestication of sulfur autotrophic denitrifying bacteria. The influent of the anoxic tank of the sewage treatment plant is used as the water source, and the hydraulic retention time is controlled to be consistent with that of the anoxic tank. The denitrification load and pH value are adjusted to the preset range by adding carbon source or alkaline buffer; The reagent ratio is determined according to the liquid sulfur source, the carbon source or the alkaline buffer, and the ratio is used to prepare a mixed nutritional denitrification electron donor, which is used as a denitrification electron donor in the denitrification system of the sewage treatment anoxic tank.

2. The method according to claim 1, characterized in that: The method of adjusting the denitrification load and pH value to a preset range by adding a carbon source or an alkaline buffer comprises: Obtaining the denitrification load in the denitrification process according to the nitrate concentration; Determining whether the denitrification load is less than the preset load value; If it is less than the preset load value, adding a carbon source to the simulated reactor until the denitrification load is not less than the preset load value; Determine whether the pH value is not less than a preset pH value; if it is less than the preset pH value, add an alkaline buffer until the pH value is not less than the preset pH value.

3. The method according to claim 1, characterized in that The method uses a simulated reactor to simulate a sewage anoxic pool and uses a liquid sulfur source as an electron donor to cultivate denitrifying bacteria to complete the domestication of sulfur autotrophic denitrifying bacteria, including: Inoculating sludge from anoxic tanks of a sewage treatment plant in a simulated reactor, using influent from the anoxic tanks of the sewage treatment plant as a water source; determining the amount of the liquid sulfur source to be added according to the concentration of nitrate in the simulated reactor; The liquid sulfur source is added to the simulated reactor according to the added amount; the nitrate concentration in the simulated reactor is monitored, and the denitrification rate is obtained according to the nitrate concentration. If the denitrification rate tends to be stable, it is determined that the sulfur autotrophic denitrifying bacteria have been successfully domesticated.

4. The method according to claim 3, characterized in that: The step of determining the amount of the liquid sulfur source to be added according to the concentration of nitrate radicals comprises: Determine the amount of sulfur required based on a nitrogen-sulfur ratio of 1:1.1; The amount of the liquid sulfur source to be added is determined according to the amount of sulfur element and the ratio of the amount of sulfur element to the amount of the liquid sulfur source.

5. The method according to claim 2, characterized in that: The step of obtaining the denitrification load in the denitrification process according to the nitrate concentration includes: Obtaining the nitrate concentration before and after a preset period, and obtaining the denitrification rate of the period according to the ratio of the change in the nitrate concentration to the corresponding time interval; The denitrification load is obtained according to the denitrification rate.

6. The method according to claim 1, characterized in that The liquid sulfur source is sodium sulfide or liquid sodium thiosulfate.

7. The method according to claim 2, characterized in that The preset pH value is set in the range of 6.5 to 8.

0.

8. The method according to claim 2, characterized in that: The alkaline buffer is sodium carbonate or sodium bicarbonate.

9. A mixed nutritional denitrification electron donor, characterized in that: A mixture comprising one or more of a liquid sulfur source, a carbon source and an alkaline buffer mixed in a preset ratio, wherein the preset ratio is a ratio obtained according to the method according to any one of claims 1-8.

10. An anoxic tank denitrification system, characterized in that: It includes the mixed nutrition type denitrification electron donor as described in claim 9.

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