Hot melt adhesive immobilized wood fiber bacteria and algae biofilm carrier and preparation method

Abstract

The present invention discloses a hot melt adhesive immobilized wood fiber algae biofilm carrier and its preparation method. The hot melt adhesive is heated to 150-190 ° C and completely melted before being evenly sprayed on a hard flat substrate. The spraying amount is 60-500 g·m 2 . 10-60 mesh dried granular wood fiber waste is evenly laid on a hard flat substrate sprayed with hot melt adhesive, and the wood fiber waste is mechanically compacted at a pressure of 30-50 kPa for 10-15 seconds, and then cooled to obtain an immobilized wood fiber bacteria and algae biofilm carrier. The hot melt adhesive immobilized wood fiber carrier of the present invention can effectively utilize biomass waste as a resource, and the formed carrier has a rough surface, a large specific surface area, developed pores, no physiological toxicity, and can significantly promote the attachment of bacteria and algae cells; and the preparation process is simple, the reusability is high, and the economic cost is low, and it can be widely used in the biofilm culture of microalgae and the bacteria and algae biofilm wastewater treatment technology.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage biological treatment and relates to a hot melt adhesive immobilized wood fiber bacteria and algae biofilm carrier and a preparation method thereof. Background Art

[0002] In today's society, driven by technological demands for sustainable development and energy conservation and emission reduction, algae-bacteria symbiotic wastewater treatment technology and its related processes have garnered significant attention. Currently, three types of symbiotic systems widely used in wastewater treatment are suspended, immobilized, and biofilm systems. These systems primarily exist in suspended, immobilized, and biofilm forms. In suspended systems, microalgae, due to their small size and density similar to that of water, tend to remain suspended in the water, easily discharging with the effluent, causing algal cell loss and compromising wastewater treatment effectiveness. Immobilization can effectively overcome the drawbacks of suspended algae, but its widespread application is hampered by the high cost of embedding matrices, the difficulty in finding non-toxic and harmless matrices, and the cumbersome and complex operation. To overcome the bottlenecks of these two symbiotic technologies, biofilm systems have emerged. Biofilm systems involve microorganisms immobilized on the surface of a solid medium, forming a biofilm that naturally separates the biomass from the wastewater medium. The biofilm system has the advantages of simple biomass harvesting, convenient system operation, fast mass transfer rate, high light energy utilization efficiency, and low infrastructure investment cost.

[0003] Biofilm carriers are the medium upon which microorganisms in biofilm systems rely for survival and are the core component of biofilm processes. They directly influence microbial growth and reproduction, as well as the biomass within the reactor. To ensure the economic and practical application of biofilm technology, the carriers should be environmentally friendly, inexpensive, widely distributed, easily accessible, durable, and non-biotoxic. Lignocellulose is a widely available and abundant biomass resource with numerous advantages, including environmental friendliness, sustainability, biodegradability, and renewable properties. Its excellent water-holding properties and naturally rough surface effectively promote the attachment and biofilm formation of microalgae cells. However, as carriers in submerged membrane systems, they are light and difficult to settle. Their simple, loose accumulations are easily washed away by water in biofilm systems where there is relative displacement between the wastewater and the carrier. Immobilizing lignocellulosic particle carriers to form carrier modules on inexpensive glass substrates or block materials effectively addresses this issue. These immobilized particle carrier modules can be arranged horizontally or vertically to meet the requirements of different systems, and the resulting biofilm can be harvested by simple scraping.

[0004] Hot melt adhesive is environmentally friendly, non-toxic, boasts a huge annual production volume, is inexpensive, offers excellent versatility, and offers excellent bonding properties. It can bond nearly all materials, making it the most widely used hot melt adhesive for wood products. Its stable properties, resistance to biodegradation, and excellent light transmittance make it particularly suitable for bonding and fixing granular wood fiber materials. Therefore, hot melt adhesive can be used to immobilize granular wood fiber materials to create economical and efficient bacterial and algal biofilm carriers for wastewater treatment, providing a technological foundation for reducing energy consumption, carbon emissions, and resource utilization in my country's wastewater treatment. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of existing bacterial and algal biofilm carriers, such as high cost, poor durability, low cell attachment efficiency, and non-renewability, by providing a hot-melt adhesive-immobilized wood fiber bacterial and algal biofilm carrier and its preparation method. This immobilized carrier features a rough surface, large specific surface area, diverse morphologies, high bacterial and algal cell attachment efficiency, and is environmentally friendly and non-toxic. The preparation process is simple, suitable for industrial production, and can achieve efficient utilization of biomass resources.

[0006] The technical solution of the present invention is: a hot melt adhesive immobilized wood fiber bacteria and algae biofilm carrier and a preparation method thereof, comprising the following steps:

[0007] (1) Place the hot melt adhesive in a melting device and heat it to 150-190°C to completely melt it. Use a spraying device to evenly spray it on a hard flat substrate. The spraying amount is 60-500g·m -2 .

[0008] (2) Immediately spread 10-60 mesh dry granular wood fiber waste evenly on the flat base, with a laying amount of 100-400 g·m -2 Then, the wood fiber waste is mechanically compacted at a pressure of 30-50 kPa for 10-15 seconds, and after cooling, an immobilized wood fiber bacteria-algae biofilm carrier with a rough surface and rich pores is obtained.

[0009] The hard flat substrate of the present invention is a hard flat material with a thickness of 0.2-2 cm, preferably a glass plate, an organic glass plate, a plastic plate or a metal plate.

[0010] The granular wood fiber waste of the present invention is agricultural and forestry waste biomass, preferably sawdust, bagasse, rice husk or bamboo chips.

[0011] The hot melt adhesive described in the present invention is ethylene vinyl acetate copolymer (EVA), polyamide (PA), polyolefin (PO), polyester (PES) and the like, preferably EVA and PA.

[0012] Compared with existing biofilm carriers and preparation methods, the present invention has the following advantages.

[0013] 1. Using a sprayed hot-melt adhesive to bond the granular wood fiber waste to a hard, flat substrate is simple, convenient, and continuously operable, making it suitable for industrial production. The hot-melt adhesive, substrate, and granular wood fiber waste are all inexpensive, readily available, and common materials. Furthermore, the substrate can be reused by reheating the substrate and adding additional granular wood fiber material, thus overcoming the bottlenecks of traditional substrates, which often face complex manufacturing processes, high material costs, and low reusability.

[0014] 2. Hot melt adhesive and wood fiber materials have good biocompatibility and no physiological toxicity. Their decomposition products have no toxic side effects on the environment when they are in wastewater for a long time, effectively breaking through the secondary pollution problem of traditional carriers.

[0015] 3. The naturally rough surface of the wood fiber material bonded to the substrate, with well-developed pores and rich morphology, provides abundant attachment sites for algal cells, buffering fluid shear stress and promoting cell attachment, resulting in excellent biofilm formation. Furthermore, the wood fiber material effectively absorbs water and nutrients, providing a slow-release effect for the growth and reproduction of microalgae and bacteria, effectively overcoming the bottleneck of poor biofilm formation on traditional carriers. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a flow chart of an embodiment of the present invention.

[0017] Figure 2 Schematic diagram of the photobioreactor used in the embodiment of the present invention. DETAILED DESCRIPTION

[0018] The present invention will be further described through the following embodiments with reference to the accompanying drawings.

[0019] Example 1.

[0020] like Figure 1 As shown, adjust the hot melt adhesive spraying equipment, control the adhesive application temperature to 180℃, and the adhesive application amount to 80g·m -2 By mechanically compacting 30-40 mesh sawdust, the action pressure is controlled to be 30kPa and the action time is 10s. Figure 2 In the photobioreactor shown, a mixed seed solution of Chlorella vulgaris and Bacillus lysinicola (microalgae: bacteria = 20:1, wet weight ratio) cultured to the logarithmic growth phase with an initial OD680 of 1.0 was pumped into the biofilm carrier of the channel through a peristaltic pump. After one day of flow biofilm inoculation, the culture solution was replaced with synthetic wastewater, and the peristaltic pump pumped the wastewater into the reaction system. 800 mL of wastewater in the conical flask circulated through the system and flowed over the surface of the biofilm carrier at a circulation flow rate of 10 mL min -1 Wastewater related indicators before treatment: NH4 + -N(229.5mg·L-1 )、TN(296mg·L -1 )、TOC(442.1mg·L -1 ), TP (19.2 mg·L -1 ). When the light intensity is 120 μmol·m -2 ·s -1 After culturing at 25°C for 15 days, the yield of the biofilm obtained on the carrier was 39.58 g·m -2 , for the removal of pollutants in wastewater: NH4 + -N (67.97%), TN (62.74%), TOC (71.16%), TP (41.46%).

[0021] Example 2.

[0022] like Figure 1 As shown, adjust the hot melt adhesive spraying equipment, control the adhesive application temperature to 180℃, and the adhesive application amount to 160g·m -2 By mechanically compacting 30-40 mesh bamboo chips, the action pressure is controlled to be 30kPa and the action time is 10s. Figure 2 In the photobioreactor shown, a mixed seed solution of Chlorella vulgaris and Bacillus lysinicola (microalgae: bacteria = 20:1, wet weight ratio) cultured to the logarithmic growth phase with an initial OD680 of 1.0 was pumped into the biofilm carrier of the channel through a peristaltic pump. After one day of flow biofilm inoculation, the culture solution was replaced with synthetic wastewater, and the peristaltic pump pumped the wastewater into the reaction system. 800 mL of wastewater in the conical flask circulated through the system and flowed over the surface of the biofilm carrier at a circulation flow rate of 10 mL min -1 Wastewater related indicators before treatment: NH4 + -N(229.5mg·L -1 )、TN(296mg·L -1 )、TOC(442.1mg·L -1 ), TP (19.2 mg·L -1 ). When the light intensity is 120 μmol·m -2 ·s -1 After culturing at 25°C for 15 days, the yield of the biofilm obtained on the carrier was 44.35 g·m -2 , for the removal of pollutants in wastewater: NH4 + -N (65.23%), TN (67.67%), TOC (79.53%), TP (39.18%).

[0023] Example 3.

[0024] like Figure 1As shown, adjust the hot melt adhesive spraying equipment, control the adhesive application temperature to 180℃, and the adhesive application amount to 310g·m -2 By mechanically compacting 40-50 mesh bamboo chips, the action pressure is controlled to be 30kPa and the action time is 10s. Figure 2 In the photobioreactor shown, a mixed seed solution of Chlamydomonas and Bacillus shenkelii (microalgae: bacteria = 50:1, wet weight ratio) cultured to the logarithmic growth phase with an initial OD680 of 1.0 was pumped into the biofilm carrier of the channel by a peristaltic pump. After one day of flow biofilm inoculation, the culture solution was replaced with synthetic wastewater, and the peristaltic pump pumped the wastewater into the reaction system. 800 mL of wastewater in the conical flask circulated through the system and flowed over the surface of the biofilm carrier at a circulation flow rate of 10 mL min -1 Wastewater related indicators before treatment: NH4 + -N(225.5mg·L -1 )、TN(288.2mg·L -1 )、TOC(422.6mg·L -1 )、IC(455mg·L -1 ), TP (16.2 mg·L -1 ). When the light intensity is 120 μmol·m -2 ·s -1 After culturing at 25°C for 15 days, the yield of the biofilm obtained on the carrier was 55.8 g·m -2 , the removal rates of pollutants in wastewater are: NH4 + -N (98.60%), TN (90.63%), TOC (76.52%), IC (92.92%), TP (62.77%).

[0025] The above description merely represents the preferred embodiments of the present invention, and while the description is relatively specific and detailed, it should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications, improvements, and substitutions without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a hot melt adhesive immobilized wood fiber bacteria and algae biofilm carrier, characterized in that: The preparation method comprises the following steps: (1) Place the hot melt adhesive in a melting device and heat it to 150-190°C to completely melt it. Use a spraying device to evenly spray it on a hard flat substrate. The spraying amount is 60-500g·m -2 ; (2) Immediately spread 10-60 mesh dry granular wood fiber waste evenly on a hard flat substrate, with a laying amount of 100-400 g·m -2 Then, the wood fiber waste is mechanically compacted at a pressure of 30-50 kPa for 10-15 seconds, and after cooling, an immobilized wood fiber bacteria-algae biofilm carrier with a rough surface and rich pores is obtained.

2. The preparation method according to claim 1, characterized in that The hard plane substrate is a hard plane plate made of a glass plate, a plastic plate or a metal plate; the thickness of the hard plane substrate is 0.2-2 cm.

3. The preparation method according to claim 1, characterized in that The hard plane base is a hard plane plate made of organic glass plate; the thickness of the hard plane base is 0.2-2 cm.

4. The preparation method according to claim 1, characterized in that The granular wood fiber waste is agricultural and forestry waste biomass, which is sawdust, bagasse or rice husk.

5. The preparation method according to claim 1, characterized in that The granular wood fiber waste is agricultural and forestry waste biomass, which is bamboo chips.

6. The preparation method according to claim 1, characterized in that The material of the hot melt adhesive is any one or more mixtures of polyamide, polyolefin or polyester.

7. The preparation method according to claim 1, characterized in that The material of the hot melt adhesive is any one or more mixtures of ethylene-vinyl acetate copolymer, polyamide, or polyester.

8. A hot melt adhesive immobilized wood fiber bacteria and algae biofilm carrier prepared by the method according to any one of claims 1 to 7.

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