Rapid start-up method of biofilm system based on sulfur-based nano-ceramic carrier and biofilm system

Abstract

The present application relates to a rapid start-up method for a biofilm system based on a sulfur-based nano-ceramic carrier and a biofilm system. The rapid start-up method for a biofilm system based on a sulfur-based nano-ceramic carrier comprises the following steps: (1) adding low-valent sulfur element during the nano-ceramic preparation process to form a sulfur-based nano-ceramic carrier; (2) selecting surface soil, configuring different substrates and culture media on the soil to screen different functional bacterial genera; (3) spraying the bacterial species to be inoculated on the surface of the sulfur-based nano-ceramic carrier to form a biofilm structure, and placing the biofilm structure in a water collection and circulation device to complete the initial biofilm formation; (4) after the initial biofilm formation on the carrier in step (3) is completed, the functional bacterial genera are colonized by sulfur autotrophic denitrifying bacteria or autotrophic nitrifying bacteria; (5) after the biofilm is formed on the surface of the sulfur-based nano-ceramic carrier, the formation of the biofilm is promoted by optimizing the water inlet load and the hydraulic retention time, thereby achieving biofilm formation based on the sulfur-based nano-ceramic carrier.

Description

Technical Field

[0001] The present invention relates to the field of biological sewage treatment, and in particular to a rapid start-up method of a biofilm system based on a sulfur-based nano-ceramic carrier and a biofilm system. Background Art

[0002] In recent years, with the continuous growth of population and urbanization, a large amount of domestic and industrial wastewater has been generated. If discharged directly without treatment, it will inevitably cause significant damage to natural water bodies and drinking water. Wastewater treatment methods generally include physical, chemical, and biological methods. However, physical and chemical methods are less economical and efficient than biological methods due to their high energy consumption and secondary pollution. However, the biological wastewater treatment process is often accompanied by significant energy consumption, especially aeration energy consumption, which can account for over 50% of the total wastewater treatment energy consumption. Therefore, how to break the "energy-based pollution control" trend and seek low-energy, low-chemical, and high-efficiency wastewater treatment technologies.

[0003] Biofilm systems achieve large-scale microbial enrichment on material surfaces, effectively immobilizing dominant functional bacteria and unleashing their degradation capabilities. Compared to traditional activated sludge processes, biofilm systems offer irreplaceable advantages. However, the key to achieving efficient and stable biofilm treatment performance lies in rapidly forming biofilms of specific functional bacteria on material surfaces. Therefore, there is an urgent need for a biofilm treatment technology that is both energy-efficient and chemical-efficient, and that can rapidly activate such systems. Summary of the Invention

[0004] To overcome the problems existing in related technologies, this application provides a rapid startup method and biofilm system based on a sulfur-based nanoceramic carrier. This method can accelerate the colonization of functional bacterial species and shorten the startup cycle, achieving the goals of rapid startup and low-energy, high-efficiency treatment of the biofilm system. The biofilm system constructed based on this method requires no aeration or secondary addition of a denitrifying carbon source, offers flexible configuration, and can significantly reduce wastewater treatment costs and management difficulties.

[0005] To achieve the above objectives, according to one aspect of the present invention, the present application provides a rapid start-up method for a biofilm system based on a sulfur-based nano-ceramic carrier, which comprises the following steps:

[0006] (1) Nanoceramic carrier modification: sulfur-based nanoceramic carriers are formed by adding low-valent sulfur elements during the preparation of nanoceramics;

[0007] (2) Screening of functional bacterial genera: Select surface soil, pre-treat the soil to obtain microorganisms, and screen different functional bacterial genera by configuring different substrates and culture media on the soil;

[0008] (3) Inoculation of functional bacteria: Spray the bacteria species to be inoculated on the surface of the sulfur-based nano-ceramic carrier to form a biofilm structure, and place the biofilm structure in a water collection and circulation device to complete the initial biofilm formation;

[0009] (4) Colonization of functional bacteria: After the initial biofilm formation on the carrier in step (3) is completed, the functional bacteria are colonized by sulfur autotrophic denitrifying bacteria or autotrophic nitrifying bacteria;

[0010] (5) Biofilm acclimation: After the biofilm is formed on the surface of the sulfur-based nano-ceramic carrier, when the COD removal rate of the wastewater in the water collection and circulation device is greater than 80%, the ammonia nitrogen removal rate is greater than 90%, and the total nitrogen removal rate is greater than 70%, the intermittent flow is changed to a continuous flow. By optimizing the influent load and the hydraulic retention time, the formation of the biofilm is promoted, and the biofilm formation based on the sulfur-based nano-ceramic carrier is achieved.

[0011] Preferably, the preparation of the nanoceramic includes the following steps: 2.1 using a precipitation method, uniformly mixing an aluminum chloride solution, a precipitant and a surfactant, and forming nano-alumina particles with a smaller particle size under a precipitation temperature range of 40-50°C; 2.2 the nano-alumina particles are calcined, crushed and pressed to form a nano-ceramic material; wherein the concentration of the aluminum chloride solution is 0.2-0.4M, the precipitant is sodium hydroxide or sodium carbonate, and the surfactant is polyethylene glycol 600 or polyethylene glycol 1500; the calcination temperature range is 400-500°C, the crushing method is ultrasonic crushing, and the pressing method is plate pressing to form a film.

[0012] Preferably, the surface modification of the nano-ceramic material is to load iron sulfide on the surface of the material by laser cladding, so that it serves as a metabolic substrate for sulfur autotrophic denitrifying functional bacteria, and the iron sulfide sprayed on the surface of the nano-ceramic material accounts for 5-10%.

[0013] Preferably, the laser spraying speed is 1-10 mm / s, the laser input power is 1-2 kW, the laser spot diameter is 4-8 mm, and the overlap rate is 20-60%.

[0014] Preferably, in the step of screening functional bacteria, pre-treating the soil comprises the following steps:

[0015] 3.1. Dilute the soil with water at a soil-to-water ratio of 2:1, 3:1, or 4:1. 3.2 Ultrasonicate the diluted soil again to remove inorganic particles and microorganisms attached to plant rhizomes. 3.3 Filter the soil suspension to remove larger inorganic particles and plant rhizomes. The ultrasonic frequency should be 300-600W and the ultrasonic time should be 30-60 minutes.

[0016] Preferably, the method of screening different functional bacterial genera by configuring different substrates and culture media on the soil includes the following steps: 4.1. diluting the filtered soil suspension to ensure that the initial mixed solution has a suspended solids concentration of 10,000 mg / L; 4.2 selecting sodium acetate or glucose as a carbon source for screening heterotrophic bacteria, selecting ammonium chloride as a nitrogen source for screening autotrophic nitrifying bacteria, and selecting potassium nitrate as a nitrogen source and a reduced sulfur source as a sulfur source for screening sulfur autotrophic denitrifying bacteria; 4.3 selecting ammonium chloride and potassium dihydrogen phosphate as culture media, wherein the ammonia nitrogen concentration in the culture media is 10-20 mg / L and the phosphorus concentration is 2-4 mg / L; 4.4. uniformly mixing the pretreated soil and the culture media, screening and enriching the resulting heterotrophic bacterial suspension, and then conducting three rounds of beaker experiments to allow the soil bacterial suspension to migrate into the culture media.

[0017] Preferably, the culture conditions for the autotrophic nitrifying bacteria are pH 7.0-8.0, temperature 20.0-30.0°C, and dissolved oxygen concentration 2.0-3.0 mg / L; the culture conditions for the sulfur autotrophic denitrifying bacteria are pH 6.5-8.0, temperature 20.0-30.0°C, and dissolved oxygen concentration 0.2-0.5 mg / L.

[0018] Preferably, the inoculation of the functional bacteria further comprises the following steps: 5.1 uniformly mixing the screened and enriched heterotrophic bacterial suspension with organic matter to obtain heterotrophic functional bacteria, wherein the concentration of the heterotrophic bacterial suspension is 105-107 / mL, and the organic matter is sodium acetate or glucose; 5.2 spraying heterotrophic functional bacteria on the surface of the sulfur-based nano-ceramic carrier, and placing the sulfur-based nano-ceramic carrier in a water collection and circulation device to complete the initial biofilm formation.

[0019] To achieve the above-mentioned purpose, according to another aspect of the present invention, the present application provides a biofilm system, comprising: a sulfur-based nanoceramic generator, used to provide a good growth environment for metabolic sewage microorganisms; a water collection and circulation device, a water distribution and spraying device and a precipitation device; wherein, the water collection and circulation device is used to collect sewage dripping from the bottom of the sulfur-based nanoceramic generator, and the water collection and circulation device is connected to the water distribution and spraying device, and the hydraulic retention time of the biofilm system is controlled by setting different numbers of cycles; the water distribution and spraying device is the water inlet system of the biofilm system, which is arranged above the sulfur-based nanoceramic generator, and the distance between the water distribution and spraying device and the sulfur-based nanoceramic generator is 30 to 70 cm; the precipitation device is arranged at the rear section of the biofilm system, and is used to collect aged and detached biofilms in the biofilm system to control the concentration of suspended solids in the system outlet water.

[0020] Preferably, the biofilm system is coupled into a multi-stage biofilm system according to the inlet water quality conditions and outlet water standards. Each stage of the biofilm system is equipped with a water collection and circulation device, a water distribution and spraying device, and a precipitation device. The sulfur-based nanoceramic generator is a folded vertical suspension structure.

[0021] The technical solution provided by this application may have the following beneficial effects: 1. By screening and enriching heterotrophic bacteria, autotrophic nitrifying bacteria, and sulfur autotrophic denitrifying bacteria in the soil, a preliminary biofilm is preferentially formed on the surface of a sulfur-based nano-ceramic carrier by spraying a microbial agent. The extracellular polymer secretion characteristics of the heterotrophic bacteria accelerate the colonization of the autotrophic bacteria on the carrier surface, thereby shortening the startup period. By spraying different microbial agents, a customized biofilm structure layer with different functional bacterial genera can be formed. The surface of the biofilm can achieve aerobic oxidation and nitrification functions, while the interior can achieve sulfur autotrophic denitrification functions, forming a multifunctional biofilm structure.

[0022] 2. The biofilm system based on sulfur-based nano-ceramic carriers has a large surface area of ​​biological attachment carriers. The system does not require aeration or external carbon sources, the microbial activity is high, and the overall operating cost and management difficulty are greatly reduced.

[0023] 3. The biofilm system based on the sulfur-based nano-ceramic carrier has strong adaptability to water quality fluctuations, and its C / N ratio can be 5:1 to 20:1. The hydraulic retention time can be set to different application scenarios, ranging from 2.0 to 12.0 hours.

[0024] 4. The biofilm system is flexible to assemble, occupies a small area, and is easy to integrate. It is especially suitable for areas with inconvenient transportation or limited management and operation capabilities.

[0025] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other objects, features and advantages of the present application will become more apparent through a more detailed description of exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0027] Figure 1 This is a schematic flow chart of a rapid startup method for a biofilm system based on a sulfur-based nano-ceramic carrier according to an embodiment of the present application;

[0028] Figure 2 This is a diagram showing the treatment effect of a biofilm system based on a sulfur-based nano-ceramic carrier, as shown in Example 1 of the present application;

[0029] Figure 3 This is a diagram showing the treatment effect of a biofilm system based on a sulfur-based nano-ceramic carrier, as shown in the comparative example of the present application;

[0030] Figure 4 This is a schematic diagram of the biofilm system structure shown in one embodiment of the present application. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. Instead, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0032] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. As used in this application and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0033] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0034] The technical solutions of the embodiments of the present application are described in detail below with reference to the accompanying drawings. Figure 1 This is a schematic flow chart of a rapid startup method for a biofilm system based on a sulfur-based nano-ceramic carrier, shown in one embodiment of the present application.

[0035] Example 1

[0036] A rapid start-up method for a biofilm system based on a sulfur-based nano-ceramic carrier includes the steps of modifying the nano-ceramic carrier, screening functional bacteria, inoculating and forming biofilms with functional bacteria, acclimating the biofilm, and optimizing process parameters.

[0037] Among them, nanoceramic carrier modification refers to adding low-valent sulfur elements during the preparation process of nanoceramics to prepare sulfur-based nanoceramic carrier materials, which are then used as biofilm carrier materials to achieve efficient integrated biological decarbonization and sulfur autotrophic denitrification biofilm systems.

[0038] The preparation of sulfur-based nano-ceramic carrier materials mainly includes the preparation of nano-ceramic materials and surface modification of low-valent sulfur elements.

[0039] The rapid start-up method of the biofilm system based on the sulfur-based nano-ceramic carrier comprises the following steps:

[0040] S1: Nanoceramic carrier modification: sulfur-based nanoceramic carriers are formed by adding low-valent sulfur elements during the preparation of nanoceramics;

[0041] S2: Screening of functional bacterial genera: Select surface soil, pre-treat the soil to obtain microorganisms, and screen different functional bacterial genera by configuring different substrates and culture media on the soil;

[0042] S3: Inoculation of functional bacteria: Spray the bacterial species to be inoculated on the surface of the sulfur-based nano-ceramic carrier to form a biofilm structure, and place the biofilm structure in a water collection and circulation device to complete the initial formation of the biofilm;

[0043] S4: colonization of functional bacteria: after the initial biofilm formation on the carrier in step (3) is completed, the functional bacteria are colonized by sulfur autotrophic denitrifying bacteria or autotrophic nitrifying bacteria;

[0044] S5: Biofilm acclimation: After the biofilm is formed on the surface of the sulfur-based nano-ceramic carrier, when the COD removal rate of the wastewater in the water collection and circulation device is greater than 80%, the ammonia nitrogen removal rate is greater than 90%, and the total nitrogen removal rate is greater than 70%, the intermittent flow is changed to a continuous flow. By optimizing the influent load and the hydraulic retention time, the formation of the biofilm is promoted, thereby achieving biofilm formation based on the sulfur-based nano-ceramic carrier.

[0045] In one embodiment, the nanoceramic preparation comprises the following steps:

[0046] 2.1 Using the precipitation method, the aluminum chloride solution, precipitant and surfactant are evenly mixed to form nano-alumina particles with smaller particle size under the precipitation temperature range of 40~50℃;

[0047] 2.2 The nano-alumina particles are calcined, crushed and pressed to form nano-ceramic materials;

[0048] The concentration of the aluminum chloride solution is 0.2-0.4M, the precipitant is sodium hydroxide or sodium carbonate, and the surfactant is polyethylene glycol 600 or polyethylene glycol 1500. The calcination temperature range is 400-500°C, the pulverization method is ultrasonic pulverization, and the pressing method is plate pressing to form a film.

[0049] In one embodiment, the concentration of the aluminum chloride solution is 0.3M, and the precipitant is sodium carbonate, and its concentration is 0.8M.

[0050] In one embodiment, the concentration of the surfactant is 5-15 g / L, and the surfactant is polyethylene glycol 1500 with a concentration of 10 g / L.

[0051] In one embodiment, the addition ratio of aluminum chloride, precipitant and surfactant is 20:1:2 respectively.

[0052] In one embodiment, the precipitation temperature is 45°C and the calcination temperature is 450°C.

[0053] In one embodiment, the surface modification of the nanoceramic material involves loading iron sulfide onto the material surface via laser cladding, allowing it to serve as a metabolic substrate for sulfur-autotrophic denitrifying bacteria. The iron sulfide is sprayed onto 5-10% of the nanoceramic material surface. The laser cladding speed is 1-10 mm / s, the laser input power is 1-2 kW, the laser spot diameter is 4-8 mm, and the overlap ratio is 20-60%.

[0054] In one implementation, the iron sulfide spraying accounts for 8% of the surface of the nano-ceramic material.

[0055] The sulfur-based nano-ceramic carrier prepared by the above method has a large surface area, which can effectively increase the biofilm attachment area. The surface-modified sulfur element can provide a metabolic substrate for sulfur-autotrophic denitrifying functional bacteria, and can realize the biological denitrification process without the need for an external carbon source. The iron element can effectively promote the efficiency of electron transfer between microorganisms, and has a great promoting effect on improving the pollutant removal efficiency.

[0056] In one embodiment, the inoculation of functional bacteria comprises the steps of screening and inoculating the functional bacteria. The functional bacteria are bacterial agents with efficient decarbonization and denitrification functions. The efficient decarbonization and denitrification functional bacterial agents are heterotrophic bacteria, autotrophic nitrifying bacteria, and sulfur autotrophic denitrifying bacteria selected from the soil.

[0057] In the screening step of functional bacteria, the soil pretreatment includes the following steps:

[0058] 3.1. Dilute the soil with water at a soil-to-water ratio of 2:1, 3:1, or 4:1. After the soil is retrieved, dilute it with water at a ratio of 2:1 to 4:1.

[0059] 3.2 The diluted soil is treated again by ultrasound to obtain inorganic particles in the soil and microorganisms attached to plant roots, thereby increasing the organic matter content of the pretreated soil.

[0060] 3.3 Filter the soil suspension to remove larger inorganic particles and plant roots. That is, filter the soil suspension after ultrasonic treatment to remove larger inorganic particles and plant roots.

[0061] The ultrasonic frequency is 300-600W, and the ultrasonic time is 30-60 minutes. Topsoil from areas with abundant vegetation is excavated. Forest soil with a surface color of yellowish-brown or dark brown, fine texture, and no obvious sandiness is selected from the top 0-20 cm layer. Its VSS / TSS ratio is approximately 0.3-0.4.

[0062] In one embodiment, the soil used was collected from forest land in Qingdao, Shandong Province. The surface layer had abundant perennial vegetation, and the soil texture was fine without obvious sandiness. The initial soil VSS / TSS ratio was 0.3-0.4. The results of the soil microbial community diversity analysis are shown in Table 2.

[0063] Table 2 Analysis of microbial community diversity

[0064] The following steps are involved in screening different functional bacterial genera by configuring different substrates and culture media on the soil:

[0065] 4.1. Dilute the filtered soil suspension to ensure that the initial suspended solids concentration of the mixed solution is 10,000 mg / L.

[0066] 4.2 Sodium acetate or glucose was selected as the carbon source for screening heterotrophic bacteria, ammonium chloride was selected as the nitrogen source for screening autotrophic nitrifying bacteria, and potassium nitrate was selected as the nitrogen source and a reduced sulfur source as the sulfur source for screening sulfur autotrophic denitrifying bacteria.

[0067] 4.3 Select ammonium chloride and potassium dihydrogen phosphate as the culture medium, where the ammonia nitrogen concentration in the culture medium is 10-20 mg / L and the phosphorus concentration is 2-4 mg / L. The culture medium is a culture medium for trace exogenous co-metabolites.

[0068] 4.4 The pretreated soil and culture medium were mixed evenly and then screened and enriched to obtain a heterotrophic bacterial suspension. Three rounds of beaker experiments were then performed to allow the soil bacterial suspension to migrate into the culture medium.

[0069] The concentration of sodium acetate or glucose in the heterotrophic bacteria screening medium is 500-1000 mg / L, the concentration of ammonia nitrogen in the autotrophic nitrifying bacteria screening medium is 50-100 mg / L, the concentration of nitrate nitrogen in the sulfur autotrophic denitrifying functional bacteria screening medium is 50-100 mg / L, the concentration of the reducing sulfur source is 100-300 mg S / L, and the ratio of sulfur to nitrogen is 2-3.

[0070] Trace exogenous co-metabolites include low concentrations of nitrogen and phosphorus, trace elements, and macroelements. The low concentrations of nitrogen and phosphorus are ammonium chloride and potassium dihydrogen phosphate. The ammonia nitrogen concentration of the culture medium is 10-20 mg / L, the phosphorus concentration of the culture medium is 2-4 mg / L, and the trace and macroelements are shown in Table 1.

[0071] Table 1 Major and trace elements

[0072]

[0073] The following steps are involved in screening different functional bacterial genera by configuring different substrates and culture media on the soil:

[0074] 4.1. Dilute the filtered soil suspension to ensure that the initial suspended solids concentration of the mixed solution is 10,000 mg / L;

[0075] 4.2 Select sodium acetate or glucose as the carbon source for screening heterotrophic bacteria, select ammonium chloride as the nitrogen source for screening autotrophic nitrifying bacteria, and select potassium nitrate as the nitrogen source and a reduced sulfur source as the sulfur source for screening sulfur-autotrophic denitrifying bacteria;

[0076] 4.3 Select ammonium chloride and potassium dihydrogen phosphate as the culture medium, where the ammonia nitrogen concentration in the culture medium is 10-20 mg / L and the phosphorus concentration is 2-4 mg / L;

[0077] 4.4 The pretreated soil and culture medium are mixed evenly, followed by screening and enrichment to obtain a heterotrophic bacterial suspension. Three rounds of beaker experiments are then conducted to allow the soil bacterial suspension to migrate into the culture medium. Specifically, the pretreated soil and culture medium are mixed evenly, followed by screening and enrichment. Three rounds of beaker experiments are conducted, with COD, ammonia nitrogen, and nitrate nitrogen removal rates being the study targets. Changes in these removal rates are continuously observed. When the removal rate exceeds 50%, a certain proportion of the soil bacterial suspension is transferred to new culture medium, concluding the first round of beaker experiments. When the removal rate exceeds 80%, a certain proportion of the bacterial suspension is again transferred to new culture medium, concluding the second round of beaker experiments. Repeat the above steps for a third round of beaker experiments. The third round of beaker experiments is concluded when the OD600 absorbance value measured at a wavelength of 600 nm is greater than 0.1. The transfer ratio of the soil bacterial suspension to the culture medium is 5-15%, preferably 10%.

[0078] The culture conditions for the heterotrophic bacteria and the autotrophic nitrifying bacteria are pH 7.0-8.0, temperature 20.0-30.0°C, and dissolved oxygen concentration 2.0-3.0 mg / L. The culture conditions for the sulfur autotrophic denitrifying bacteria are pH 6.5-8.0, temperature 20.0-30.0°C, and dissolved oxygen concentration 0.2-0.5 mg / L.

[0079] The inoculation of functional bacteria includes the initial biofilm formation and colonization of functional bacteria. The initial biofilm formation refers to the preferential spraying of heterotrophic functional bacteria on the nanoceramic surface, forming a biofilm structure dominated by heterotrophic bacteria on the carrier surface, thereby accelerating the subsequent biofilm growth of autotrophic bacteria.

[0080] The inoculation of the functional bacteria also includes the following steps:

[0081] 5.1 The screened and enriched heterotrophic bacterial suspension is mixed evenly with organic matter to obtain heterotrophic functional bacteria. The concentration of the heterotrophic bacterial suspension is 105-107 / mL, and the organic matter is sodium acetate or glucose.

[0082] 5.2 Spray heterotrophic functional bacteria on the surface of the sulfur-based nano-ceramic carrier and place the sulfur-based nano-ceramic carrier in a water collection and circulation device to complete the initial formation of the biofilm.

[0083] Specifically, the screened and enriched heterotrophic bacterial suspension is evenly mixed with a certain concentration of organic matter. During the initial biofilm formation stage, the ventilation windows are kept open to maintain a good ventilation environment within the system. When the COD removal rate in the water collection and circulation device exceeds 80%, spraying is terminated, the incoming water is replaced, and intermittent flow is replaced with continuous flow until a visible film forms on the carrier surface, marking the end of the initial biofilm formation.

[0084] In one embodiment, the concentration of the heterotrophic bacterial suspension is 106 / mL, and the organic matter is glucose with a concentration of 1000 mg / L.

[0085] The colonization of functional bacteria refers to the colonization of sulfur autotrophic denitrifying bacteria and autotrophic nitrifying bacteria after the initial biofilm formation on the carrier is completed. Sulfur autotrophic denitrifying bacteria are selected for colonization, and potassium nitrate and a reducing sulfur source are used as the influent substrate, which are evenly mixed with the sulfur autotrophic denitrifying bacteria. The nitrate nitrogen concentration is 50 mg / L, and the reducing sulfur source concentration is 150 mg S / L. The bacterial concentration of the functional denitrifying bacteria is 107-109 / mL, preferably 108 / mL. During the sulfur autotrophic denitrifying bacteria colonization phase, the ventilation windows are kept closed to maintain the system in a closed environment. When the nitrate nitrogen removal rate in the water collection and circulation device is greater than 50%, the spraying is terminated, and the influent is replaced with a mixture of autotrophic nitrifying bacteria and ammonium chloride, and the functional bacteria of the autotrophic nitrifying bacteria are colonized simultaneously.

[0086] In one embodiment, the selected concentration of Nitrifying Bacteria is 107-109 / mL, preferably 108 / mL. The preferred ammonia nitrogen concentration is 50 mg / L. During the autotrophic nitrifying bacteria colonization phase, the ventilation windows are kept open to maintain a well-ventilated environment within the system. Spraying is terminated when the ammonia nitrogen concentration in the water collection and circulation device is less than 5.0 mg / L and the total nitrogen concentration is less than 10.0 mg / L. The influent is replaced with a mixture of heterotrophic functional bacteria, and the initial biofilm formation process described above is repeated.

[0087] In the biofilm formation stage, a certain proportion of trace and major elements were added to the mixed solution as shown in Table 1, and the pH of the bacterial solution was maintained at 7.0-8.0 and the temperature was maintained at 20.0-30.0°C.

[0088] The acclimation of the biofilm consists of the following steps:

[0089] After the biofilm formation is complete, a biofilm structure dominated by sulfur-autotrophic denitrifying bacteria, autotrophic nitrifying bacteria, and heterotrophic bacteria forms on the surface of the nano-ceramic carrier. The biofilm has a clear dissolved oxygen gradient, with the bottom layer of the biofilm being an anoxic or anaerobic zone and the surface layer being an aerobic zone. During this stage, the biofilm is acclimated. The influent during the acclimation phase is the actual treated wastewater. In the early stages of acclimation, the system is set up with intermittent flow. When the COD removal rate of the wastewater in the water collection and circulation device is greater than 80%, the ammonia nitrogen removal rate is greater than 90%, and the total nitrogen removal rate is greater than 70%, the intermittent flow is changed to continuous flow.

[0090] In one of the embodiments, process parameter optimization mainly includes influent load optimization and hydraulic retention time optimization. In order to adapt to different application scenarios, influent load optimization mainly includes setting different C / N ratios, and the C / N ratios are 2.5:1, 5:1, 10:1 and 20:1 respectively. The hydraulic retention time of the biofilm system is 12.0h. The COD and total nitrogen removal rates are the research objects. The hydraulic retention time optimization mainly sets different hydraulic retention times according to different treatment standards, which are 2.0h, 6.0h, 12.0h and 24.0h respectively, and the COD and ammonia nitrogen removal rates are the research objects. When the COD removal rate is required to be greater than 80% and the total nitrogen removal rate is required to be greater than 70%, the adaptable C / N ratio range is 5:1 to 20:1. When the COD removal rate is required to be greater than 80% and the ammonia nitrogen removal rate is required to be greater than 50%, the hydraulic retention time is preferably 6.0 to 12.0h. When the COD removal rate is required to be greater than 80%, the ammonia nitrogen removal rate is not limited. The treatment effect is as follows Figure 2 As shown in the figure, the treatment effect of the biofilm system reached stability around the 10th day, with COD, ammonia nitrogen and total nitrogen removal rates reaching 92.2%, 98.6% and 86.2%, respectively. The method of the present invention can achieve rapid startup and stable and efficient operation of the biofilm system based on the sulfur-based nano-ceramic carrier.

[0091] Example 2

[0092] This experiment followed the same treatment methods as in Experimental Example 1, except that a two-stage biofilm system was coupled during stable operation to shorten the hydraulic retention time of each biofilm stage, further investigating its treatment capacity and optimizing device compatibility. Results showed that the two-stage biofilm system with sulfur-based nanoceramic supports achieved effluent COD, ammonia nitrogen, and total nitrogen removal efficiencies of 90.2%, 96.4%, and 88.2%, respectively.

[0093] Example 3

[0094] This experimental example was treated in accordance with Experimental Example 1, except that the hydraulic retention time of the biofilm system was shortened to 2.0 h. The results showed that under high hydraulic load conditions, the biofilm system could still maintain a stable biofilm structure and retain a higher concentration of influent ammonia nitrogen, which is of great significance for treating effluent for municipal greening water use. The COD removal rate was 90.0% and the ammonia nitrogen removal rate was 10.2%, which was in line with experimental expectations.

[0095] Comparative Example

[0096] The difference from Example 1 is that:

[0097] The biofilm formation method was changed to in-situ aeration, where the biofilm carrier was immersed in a mixture containing different functional bacterial genera and aerated. During the continuous flow phase, the water inlet method was changed from spraying to a peristaltic pump, and aeration was set to provide an appropriate dissolved oxygen concentration (3-4 mg / L).

[0098] Experimental results:

[0099] Using this method to start biofilm formation, a clear biofilm structure can be observed on the carrier surface in about 20 days, but the biofilm thickness is less than that of the biofilm in Example 1 during the same period, and the biofilm started by this method has no obvious anoxic zone, which is less effective for denitrifying bacteria colonization. Figure 3 As shown, the biofilm system started by this method has a relatively long start-up period, and the COD and ammonia nitrogen removal rates are comparable to those in Example 1 (90.4% and 97.6%, respectively), but the total nitrogen removal rate of the control example (52%) is much lower than that of Example 1 (86.2%).

[0100] Figure 4 This is a schematic diagram of the biofilm system structure shown in one embodiment of the present application.

[0101] Please refer to Figure 4 A biofilm system comprises: a sulfur-based nanoceramic generator for providing a good growth environment for metabolic sewage microorganisms; a water collection and circulation device, a water distribution and spraying device and a sedimentation device; wherein, the water collection and circulation device is used to collect sewage dripped from the bottom of the sulfur-based nanoceramic generator, and the water collection and circulation device is connected to the water distribution and spraying device, and the hydraulic retention time of the biofilm system is controlled by setting different circulation times; the water distribution and spraying device is the water inlet system of the biofilm system, which is arranged above the sulfur-based nanoceramic generator, and the distance between the water distribution and spraying device and the sulfur-based nanoceramic generator is 30 to 70 cm; the sedimentation device is arranged at the rear section of the biofilm system, and is used to collect aged and detached biofilms in the biofilm system to control the concentration of suspended solids in the system effluent.

[0102] In one embodiment, the biofilm system is coupled into a multi-stage biofilm system based on influent water quality and effluent standards. Each stage is equipped with a water collection and circulation device, a water distribution and spraying device, and a sedimentation device. The sulfur-based nanoceramic generator is a folded, vertically suspended structure. A single set of biofilm carriers, when folded and suspended, has a width of 1.0 to 1.5 meters, preferably 1.2 meters, and a length of 1.8 to 2.2 meters, preferably 2.0 meters.

[0103] In one embodiment, the number of biofilm carriers in each stage of the biofilm system is 50 to 100 groups, preferably 80 groups, to ensure sufficient biomass concentration in the system.

[0104] In one embodiment, the left-right spacing between each group of biofilm carriers is 3.0-7.0 cm, preferably 5.0 cm, and the spacing between the upper and lower stacks is 3.0-7.0 cm, preferably 5.0 cm, to ensure a good ventilation environment.

[0105] In one embodiment, the biofilm system is equipped with ventilation windows to ensure a good ventilation environment and provide a good oxygen-rich environment for microorganisms.

[0106] In one embodiment, the water distribution spray device is the water inlet system of the biofilm system and is preferably located above the biofilm carrier, with a spacing of 50 cm between the carrier and the carrier. Each biofilm system is preferably equipped with 1 to 3 spray devices per square meter, preferably 2 per square meter, to ensure effective sewage spray coverage and moderate spray intensity to prevent damage to the biofilm structure on the carrier surface.

[0107] In one embodiment, the water collection and circulation device is used to collect sewage dripping from the bottom of the carrier, and is connected to the water distribution and spraying device. The hydraulic retention time of the biofilm system can be controlled by setting different circulation times.

[0108] In one embodiment, the sedimentation device is arranged at the rear section of the biofilm system to collect aged and fallen biofilms in the biofilm system to control the suspended solids concentration in the system effluent.

[0109] The embodiments of the present application have been described above. The above description is illustrative and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements to the technology in the market, or to enable other persons skilled in the art to understand the embodiments disclosed herein.

Claims

1. A rapid start-up method for a biofilm system based on a sulfur-based nano-ceramic carrier, characterized in that: The following steps are involved: (1) Nano-ceramic carrier modification: The nano-ceramic material carrier modification is to load iron sulfide on the material surface by laser cladding, so that it can serve as a metabolic substrate for sulfur autotrophic denitrifying functional bacteria. The iron sulfide spraying accounts for 5-10% of the surface of the nano-ceramic material; (2) Screening of functional bacterial genera: Select surface soil, pre-treat the soil to obtain microorganisms, and screen different functional bacterial genera by configuring different substrates and culture media on the soil; (3) Inoculation of functional bacteria: Spray the bacteria species to be inoculated on the surface of the sulfur-based nano-ceramic carrier to form a biofilm structure, and place the biofilm structure in a water collection and circulation device to complete the initial biofilm formation; (4) Colonization of functional bacteria: After the initial biofilm formation on the carrier in step (3) is completed, the functional bacteria are colonized by sulfur autotrophic denitrifying bacteria or autotrophic nitrifying bacteria; (5) Biofilm acclimation: After the biofilm is formed on the surface of the sulfur-based nano-ceramic carrier, when the COD removal rate of the wastewater in the water collection and circulation device is greater than 80%, the ammonia nitrogen removal rate is greater than 90%, and the total nitrogen removal rate is greater than 70%, the intermittent flow is changed to a continuous flow. By optimizing the influent load and the hydraulic retention time, the formation of the biofilm is promoted, and the biofilm formation based on the sulfur-based nano-ceramic carrier is achieved; The nano-ceramic preparation comprises the following steps: 2.1 Using the precipitation method, the aluminum chloride solution, precipitant and surfactant are evenly mixed to form nano-alumina particles with smaller particle size under the precipitation temperature range of 40~50℃; 2.2 The nano-alumina particles are calcined, crushed and pressed to form nano-ceramic materials; The concentration of the aluminum chloride solution is 0.2-0.4 M, the precipitant is sodium hydroxide or sodium carbonate, and the surfactant is polyethylene glycol 600 or polyethylene glycol 1500; The calcination temperature range is 400-500°C, the pulverization method is ultrasonic pulverization, and the pressing method is plate pressing to form a film.

2. The rapid start-up method of a biofilm system based on a sulfur-based nano-ceramic carrier according to claim 1, characterized in that: The laser spraying speed is 1-10 mm / s, the laser input power is 1-2 kW, the laser spot diameter is 4-8 mm, and the overlap rate is 20-60%.

3. The rapid start-up method of a biofilm system based on a sulfur-based nano-ceramic carrier according to claim 1, characterized in that: In the screening step of functional bacteria, the soil pretreatment includes the following steps: 3.1 Dilute the soil with water at a soil to water ratio of 2:1, 3:1 or 4:1; 3.2 The diluted soil is treated again by ultrasound to remove inorganic particles in the soil and microorganisms attached to plant roots; 3.3 Filter the soil suspension to remove larger inorganic particles and plant roots; The ultrasonic frequency is 300-600W, and the ultrasonic time is 30-60min.

4. The rapid start-up method of a biofilm system based on a sulfur-based nano-ceramic carrier according to claim 3, characterized in that: The method is to screen different functional bacteria by configuring different substrates and culture media on the soil. The following steps are involved: 4.

1. Dilute the filtered soil suspension to ensure that the initial suspended solids concentration of the mixed solution is 10,000 mg / L; 4.2 Select sodium acetate or glucose as the carbon source for screening heterotrophic bacteria, select ammonium chloride as the nitrogen source for screening autotrophic nitrifying bacteria, and select potassium nitrate as the nitrogen source and a reduced sulfur source as the sulfur source for screening sulfur-autotrophic denitrifying bacteria; 4.3 Select ammonium chloride and potassium dihydrogen phosphate as the culture medium, where the ammonia nitrogen concentration in the culture medium is 10-20 mg / L and the phosphorus concentration is 2-4 mg / L; 4.4 The pretreated soil and culture medium were mixed evenly and then screened and enriched to obtain a heterotrophic bacterial suspension. Three rounds of beaker experiments were then performed to allow the soil bacterial suspension to migrate into the culture medium.

5. The rapid start-up method of a biofilm system based on a sulfur-based nano-ceramic carrier according to claim 4, characterized in that: The culture conditions for the autotrophic nitrifying bacteria are pH 7.0-8.0, temperature 20.0-30.0°C, and dissolved oxygen concentration 2.0-3.0 mg / L; the culture conditions for the sulfur autotrophic denitrifying bacteria are pH 6.5-8.0, temperature 20.0-30.0°C, and dissolved oxygen concentration 0.2-0.5 mg / L.

6. The rapid start-up method of a biofilm system based on a sulfur-based nano-ceramic carrier according to claim 4, characterized in that: The inoculation of the functional bacteria also includes the following steps: 5.1 The screened and enriched heterotrophic bacterial suspension is mixed evenly with organic matter to obtain heterotrophic functional bacteria. The concentration of the heterotrophic bacterial suspension is 105-107 / mL, and the organic matter is sodium acetate or glucose. 5.2 Spray heterotrophic functional bacteria on the surface of the sulfur-based nano-ceramic carrier and place the sulfur-based nano-ceramic carrier in a water collection and circulation device to complete the initial formation of the biofilm.

7. A biofilm system for implementing the method according to any one of claims 1 to 6, characterized in that: include: Sulfur-based nano-ceramic generator, used to provide a good growth environment for metabolic wastewater microorganisms; Water collection and circulation device, water distribution and spraying device and sedimentation device; The water collection and circulation device is used to collect the sewage dripped from the bottom of the sulfur-based nano-ceramic generator. The water collection and circulation device is connected to the water distribution and spraying device, and the hydraulic retention time of the biofilm system is controlled by setting different circulation times. The water distribution spray device is the water inlet system of the biofilm system and is arranged above the sulfur-based nano-ceramic generator. The distance between the water distribution spray device and the sulfur-based nano-ceramic generator is 30 to 70 cm. The sedimentation device is arranged at the rear section of the biofilm system and is used to collect aged and fallen biofilms in the biofilm system to control the suspended solids concentration in the system effluent.

8. The biofilm system according to claim 7, characterized in that: The biofilm system is coupled into a multi-level biofilm system according to the inlet water quality conditions and outlet water standards. Each level of the biofilm system is equipped with a water collection and circulation device, a water distribution and spraying device, and a precipitation device. The sulfur-based nano-ceramic generator is a folded vertical suspension structure.

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