Preparation method of iron-loaded active bamboo charcoal microbial carrier

Abstract

The invention provides a preparation method of an iron-loaded active bamboo charcoal microbial carrier. The preparation method comprises the following steps: (1) selecting and preparing materials; wherein the step (1) further comprises the following steps: (1) selecting and pretreating raw materials; (2) preparing an active bamboo charcoal microbial carrier; (3) preparing an iron-loaded active bamboo charcoal microbial carrier; and (2) filling the reactor with the iron-loaded activated bamboo charcoal microbial carrier prepared in the step (1), wherein the filling ratio is 40%. The carrier material is low in price, convenient to prepare and diverse in form, and raw materials of different sizes can be selected for preparation according to different working conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of iron-loaded activated bamboo charcoal microbial carriers, and in particular relates to a preparation method of an iron-loaded activated bamboo charcoal microbial carrier. Background Art

[0002] With the rapid development of water treatment technology, the performance of microbial carriers, as the core material of the biofilm process, directly affects the nitrogen and phosphorus removal efficiency and operating costs of sewage treatment systems. Traditional microbial carriers (such as plastic fillers such as polyethylene and polypropylene) have the following technical bottlenecks:

[0003] 1. Environmental compatibility issues: Plastic carriers are easily broken after long-term use, forming microplastic pollution. Their waste disposal process poses secondary environmental risks, which is contrary to the global "plastic restriction" policy and circular economy concept.

[0004] 2. Insufficient biological affinity: Conventional carriers have limited specific surface area and single surface functional groups, which leads to a long microbial biofilm formation period (usually more than 30 days) and difficulty in targeted enrichment of functional bacterial communities.

[0005] 3. Low electron transfer efficiency: Traditional carriers lack electron donor / acceptor synergy and rely on external carbon sources during the denitrification process, increasing operating costs. Although some studies have attempted to enhance the treatment effect through the use of iron-carbon micro-electrolysis materials, iron-based materials are prone to hardening and passivation, resulting in poor long-term operational stability.

[0006] In view of this, how to solve the defects in the above technical solutions has become one of the urgent problems to be solved in the technical field of preparation of iron-loaded activated bamboo charcoal microbial carriers. Summary of the Invention

[0007] In view of the problems existing in the background technology, the present invention provides a method for preparing an iron-loaded activated bamboo charcoal microbial carrier, comprising:

[0008] (1) Material selection and preparation

[0009] ①Selection and pretreatment of raw materials

[0010] Hollow bamboo with a diameter of 10 to 25 mm and no damage is selected as the raw material, which is cut into hollow small sections with a length of 5 to 10 mm, and then washed and dried.

[0011] ② Preparation of activated bamboo charcoal microbial carrier

[0012] The pretreated bamboo segments are carbonized in an inert gas atmosphere at a heating rate of 1-5°C / min, a carbonization temperature of 400-800°C, and a carbonization time of 2-5 hours. After carbonization, the segments are washed with deionized water to obtain an activated bamboo charcoal microbial carrier.

[0013] ③ Preparation of iron-loaded activated bamboo charcoal microbial carrier

[0014] Soak the activated bamboo charcoal microbial carrier prepared in step ② in a 10-100g / L FeCl3 solution and shake it at 60-200rmp in an air temperature-controlled shaker at room temperature for 6-24h. After taking it out, slowly add 0.05-0.5mol / L NaOH solution under magnetic stirring until the pH is 4-6, and continue shaking in an air temperature-controlled shaker for 2-8h. After taking it out, wash it repeatedly with pure water until the pH of the washing solution is 7, and dry it in a 60-80℃ oven for 6-12h to obtain an iron-loaded activated bamboo charcoal microbial carrier;

[0015] (2) filling the reactor with the iron-loaded activated bamboo charcoal microbial carrier prepared in step (1) at a filling ratio of 40%;

[0016] The reaction zone adopts a sequencing batch reactor.

[0017] The reactor is made of organic glass, with an effective volume of 5 L and an inner diameter of 20 cm;

[0018] The system air supply is provided by an aeration pump and enters the reactor through the bottom perforated pipe after being regulated by a gas flow meter;

[0019] The reactor drainage ratio is 50%, which is controlled by a solenoid valve;

[0020] During the entire operation of the reactor, the operation of all instruments is controlled by time-controlled switches.

[0021] In summary, the beneficial effects of the present invention are:

[0022] (1) The carrier material of the present invention is inexpensive, easy to prepare, and available in various forms. Raw materials of different sizes can be selected for preparation according to different working conditions.

[0023] (2) The present invention can be used to replace plastic microbial carriers, reducing the use of plastic products and the harm they cause to the environment during waste disposal.

[0024] (3) During the iron modification process, the present invention can adjust the modification parameters to enable the microbial carrier to have the characteristics of iron-carbon microelectrolysis and micromagnetic field, further improve its affinity for microorganisms, and shorten the microbial attachment and growth time.

[0025] (4) The present invention combines biomass resource utilization with functional material modification. By constructing hierarchical pores through the directional carbonization of bamboo and regulating the chemical state of iron species, it resolves the technical contradiction between the poor bioaffinity of traditional carriers and the easy inactivation of iron-based materials. The Caldilineaceae (26.40%) detected on the carrier surface in the examples are typical oligotrophic denitrifying bacteria, confirming the directional enrichment effect of the iron-carbon microenvironment on the functional bacterial community. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an image of an iron-loaded activated bamboo charcoal microbial carrier under a stereo microscope in a method for preparing an iron-loaded activated bamboo charcoal microbial carrier of the present invention;

[0027] Figure 2 This is a graph showing changes in ammonia nitrogen concentration over time in a method for preparing an iron-loaded activated bamboo charcoal microbial carrier according to the present invention;

[0028] Figure 3 The microorganisms are the top 20 in terms of relative abundance at the genus level in the biofilm on the surface of the carrier in the method for preparing the iron-loaded activated bamboo charcoal microbial carrier of the present invention.

[0029] Figure 4 The invention discloses a method for preparing an iron-loaded activated bamboo charcoal microbial carrier, a schematic diagram of nitrogen cycle metabolism in a biofilm on the carrier surface and the abundance of related functional enzymes. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions, and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Although exemplary embodiments are disclosed in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to facilitate a more thorough understanding of the present invention and to fully convey the concept of the present invention to those skilled in the art.

[0031] In the description of this specification, the description with reference to the terms "certain embodiments", "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are contradictory.

[0032] In the present invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "plurality" refers to two or more, unless expressly limited otherwise. Terms such as "installed," "connected," "connected," and "fixed" should be interpreted broadly. For example, "connected" can mean a fixed connection, a detachable connection, or an integral connection; "connected" can mean a direct connection or an indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0033] like Figure 1 As shown, this embodiment provides a method for preparing an iron-loaded activated bamboo charcoal microbial carrier.

[0034] Example 1

[0035] The specific steps of this embodiment are as follows:

[0036] (1) Material selection and preparation

[0037] ①Selection and pretreatment of raw materials

[0038] Hollow bamboo with a diameter of about 25mm and no damage is selected as the raw material, cut into hollow small sections with a length of 10mm, and then cleaned and dried.

[0039] ② Preparation of activated bamboo charcoal microbial carrier

[0040] The pretreated bamboo segments were carbonized in an inert gas atmosphere at a heating rate of 3°C / min, a carbonization temperature of 500°C, and a carbonization time of 3 hours. After carbonization, the activated bamboo charcoal microbial carrier was obtained by washing with deionized water.

[0041] ③ Preparation of iron-loaded activated bamboo charcoal microbial carrier

[0042] The activated bamboo charcoal microbial carrier prepared in step ② was immersed in a 100 g / L FeCl₃ solution and shaken at 180 rpm on an air-controlled shaker at room temperature for 6 hours. After removal, 0.5 mol / L NaOH solution was slowly added dropwise under magnetic stirring until the pH reached 4. The carrier was shaken on an air-controlled shaker for another 2 hours. After removal, the carrier was repeatedly rinsed with pure water until the pH of the washing solution reached 7. The carrier was then dried in an 80°C oven for 12 hours to obtain the iron-loaded activated bamboo charcoal microbial carrier.

[0043] (2) A sequencing batch reactor was used. The reactor was made of organic glass, had an effective volume of 5 L, and an inner diameter of 20 cm. The system air supply was provided by an aeration pump, regulated by a gas flow meter, and then entered the reactor through a perforated pipe at the bottom. The reactor drainage ratio was 50%, controlled by a solenoid valve. During the entire reactor operation, the operation of all instruments was controlled by a timer switch.

[0044] The reactor was filled with (1) to prepare the iron-loaded activated bamboo charcoal microbial carrier, with a filling ratio of 40%.

[0045] The influent water used in the experiment was taken from an actual marine aquaculture plant. To test the carrier material's effect on the enrichment of denitrifying microorganisms and its treatment of nitrogen-containing wastewater, ammonium chloride was used to supplement the influent with nitrogen, resulting in an ammonia nitrogen concentration of 10 mg / L.

[0046] The inoculum sludge was activated sludge from an actual sewage treatment plant. The concentration of activated sludge in the reactor after inoculation was 3g / L. The reactor was operated for 17 days. After the microorganisms had fully attached to the carrier surface (biofilm thickness greater than 200 microns), the sludge in the reactor was drained, the microbial community structure on the carrier surface was measured, and the system was run with water to test its ammonia nitrogen removal effectiveness.

[0047] like Figure 2 As shown, the system can fully remove 10 mg / L ammonia nitrogen in 3 hours. The biofilm attached to the carrier was scraped off, and Shanghai Meiji Biotechnology Co., Ltd. was commissioned to extract and sequence genomic DNA according to standard procedures. The highly variable regions V3 to V4 of the bacterial 16SrRNA gene were amplified using 338F and 806R primers. Sequencing and library construction analysis were performed using the Illumina MiseqTM platform; after sequencing, the effective sequences were quality controlled, and then OTU clustering was performed based on 97% sequence similarity as the standard, and classification annotation was performed against the database to obtain the taxonomic information of the bacteria, and then functional gene prediction was performed using PICRUSt2. The microbial community structure and the abundance of nitrogen cycle functional enzymes in the biofilm are shown as follows: Figure 3 and 4 As shown. The results showed that: at the family level, (1) the microbial community in the system was dominated by denitrifying functional bacteria, especially the first dominant bacteria Caldilineaceae with a relative abundance of up to 26.40%. Denitrifying bacteria can provide carbon sources for denitrifying bacteria by hydrolyzing macromolecular organic matter, and drive NO3 through the synergistic action of nitrate oxidoreductase [EC: 1.7.99.4] (sequence number 13161.96), nitrite reductase [EC: 1.7.2.1] (sequence number 1878), nitric oxide reductase [EC: 1.7.2.5] (sequence number 1025.33) and nitrous oxide reductase [EC: 1.7.2.4] (sequence number 7486). --N to N2 efficient conversion. (2) At the same time, nitrifying bacteria were found in the system, mainly Nitrospiraceae, with a relative abundance of 0.59%. Nitrifying bacteria can convert ammonia nitrogen into nitrite nitrogen through ammonia monooxygenase [EC: 1.14.99.39] (sequence number 95) and hydroxylamine dehydrogenase [EC: 1.7.2.6] (sequence number 95.5), and then convert nitrite nitrogen into nitrate nitrogen through nitrate oxidoreductase [EC: 1.7.2.6] (sequence number 13161.96). The above results confirm that the significant enrichment of denitrifying functional microorganisms in the biofilm and the denitrification process driven by them dominate the denitrification pathway. At the same time, the presence of nitrifying functional microorganisms in the system drives the nitrification process, indicating that the system has good denitrification capacity.

[0048] The present invention provides an environmentally friendly microbial carrier, which replaces plastic substrates by carbonizing bamboo, eliminating the risk of microplastic pollution from the source; by constructing a multi-level pore structure and an iron-carbon synergistic system, the three-dimensional through-pores of bamboo charcoal are used to provide a habitat for microorganisms, and at the same time, Fe is formed by controllable iron loading. 3+ / Fe 2+ Redox couple, enhancing electron transfer efficiency;

[0049] By developing a gradient pH control loading technology and preparing iron-loaded bamboo charcoal through a process of oscillation impregnation-alkaline solution slow release, the biofilm formation period was shortened from the conventional 30 days to 17 days while ensuring the stability of iron.

[0050] By synergistically regulating the carbonization temperature and iron loading, the carrier can simultaneously possess physical adsorption and biochemical synergistic effects, and can fully remove 10 mg / L ammonia nitrogen within 3 hours.

[0051] Finally, it should be noted that the above embodiments are intended to illustrate the technical solutions of the present invention only and are not intended to be limiting. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and are intended to be encompassed by the claims of the present invention.

Claims

1. A method for preparing an iron-loaded activated bamboo charcoal microbial carrier, characterized in that: include: (1) Material selection and preparation; Wherein step (1) further comprises: ①Selection and pretreatment of raw materials Use hollow bamboo with a diameter of 10-25mm and no damage as raw material, cut it into small hollow pieces with a length of 5-10mm, clean it and dry it; ② Preparation of activated bamboo charcoal microbial carrier The pretreated bamboo segments are carbonized in an inert gas atmosphere at a heating rate of 1-5°C / min, a carbonization temperature of 400-800°C, and a carbonization time of 2-5 hours. After carbonization, the segments are washed with deionized water to obtain an activated bamboo charcoal microbial carrier. ③ Preparation of iron-loaded activated bamboo charcoal microbial carrier; Soak the activated bamboo charcoal microbial carrier prepared in step ② in a 10-100 g / L FeCl3 solution and shake at 60-200 rpm in an air temperature-controlled shaker at room temperature for 6-24 hours; After taking out, slowly add 0.05-0.5 mol / L NaOH solution dropwise under magnetic stirring until the pH is 4-6, and continue shaking in an air temperature-controlled shaker for 2-8 hours; After taking it out, wash it repeatedly with pure water until the pH of the washing solution is 7, and dry it in an oven at 60-80℃ for 6-12h to obtain the iron-loaded activated bamboo charcoal microbial carrier; (2) filling the reactor with the iron-loaded activated bamboo charcoal microbial carrier prepared in step (1) at a filling ratio of 40%; The reaction zone adopts a sequencing batch reactor. The reactor is made of organic glass, with an effective volume of 5 L and an inner diameter of 20 cm; The system air supply is provided by an aeration pump and enters the reactor through the bottom perforated pipe after being regulated by a gas flow meter; The reactor drainage ratio is 50%, which is controlled by a solenoid valve; During the entire operation of the reactor, the operation of all instruments is controlled by time-controlled switches.

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