Application of magnetic adsorbent in sewage treatment plant

Abstract

The invention discloses an application method of a Fe3O4-C adsorbent for nano-plastic in water in a sewage treatment process. A magnetic adsorbent is added in an existing sewage process, so that the purposes of purifying sewage and removing micro-plastics in water are achieved. The raw material Fe3O4 (at) C nano-particles used in the invention have good acid resistance and good adsorption effect on nano-plastics, have superparamagnetism and good dispersibility, can be re-dispersed and utilized, and have the advantages of economy, environmental protection, durability and low cost. The method can be directly applied to the existing sewage treatment process.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano plastic removal in sewage treatment environments, and in particular to the application of a micro-nano plastic adsorbent in water in a sewage treatment plant. Background Art

[0002] Plastics are widely used in all walks of life. Due to their low recycling rate, a large amount of plastic waste is generated. It is estimated that by 2050, 12 billion tons of plastic waste will enter the natural world. These plastic wastes will be weathered, eroded, and decomposed into smaller plastic pollutants. Generally, plastic fragments, fibers or particles with a diameter of less than 5 mm are defined as microplastics (MPs). Microplastics have small particle sizes and large specific surface areas. The particle surface is in a metastable state. Compared with large pieces of plastic waste, microplastics are not only easy to release toxic and harmful substances in the body, but also more likely to adsorb organic pollutants, heavy metal ions or pathogens in the environmental medium. At present, microplastics have been widely detected in reservoirs, rivers, lakes, oceans and even Antarctic inland glaciers. They can enter aquatic organisms through feeding, breathing and other pathways, and accumulate in the human body along the food chain, posing a greater risk to water environment safety and human health. As an emerging pollutant, there is currently a lack of targeted removal methods in environmental water bodies and tap water.

[0003] Urban domestic sewage treatment can be divided into three processes according to the process flow, namely pretreatment, biological treatment and deep treatment. The sewage pretreatment industry mainly removes various fixed suspended impurities contained in the water. The treated sewage fails to meet the discharge standard and must be discharged after post-treatment. The sewage that has been biologically treated has removed various colloids or dissolved organic matter and impurities such as nitrogen and phosphorus contained in the water, which can further improve the sewage discharge standard. Finally, after deep treatment, on the basis of biological treatment, the residual organic matter in the sewage is removed by drugs to meet the high standard discharge and recycling requirements. At present, the traditional water process is divided into primary, secondary and tertiary levels, which shows great limitations and has certain shortcomings. For example, for smaller micron or even nano-scale plastics, it is difficult to effectively remove them through conventional filtration and coagulation methods in water plants; and the biological treatment process conditions are harsh and the cost is high. Studies have found that most micro-nano plastics in the environment are negatively charged. Therefore, it is urgent to develop low-cost, environmentally friendly, and effective removal technology for micro-nano plastics in water to ensure the safety of water environment and drinking water and protect people's health. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention is based on a previously applied patent for a magnetic adsorbent (application number: 202310127969.4), and provides an application of a magnetic nanoplastic adsorbent in sewage treatment. The adsorbent used in this method is a positively charged and imidazole-containing core-shell nanostructure with superparamagnetism. It has good adsorption performance and can be used for the removal and quantitative analysis of micro-nano plastics in water. It has a high removal rate, low cost, is green and environmentally friendly, and can be reused.

[0005] In order to solve the problems of the prior art, the technical solution adopted by the present invention is:

[0006] A method for applying a magnetic nano plastic adsorbent in sewage treatment comprises the following steps:

[0007] Step 1: Add magnetic adsorption material to the secondary sedimentation tank

[0008] By spreading the material, the superparamagnetic nanoparticle material of Fe3O4@C@pyridine is poured into the secondary sedimentation tank and stirred to fully absorb the microplastics in the water;

[0009] Step 2: Separate the adsorbent from water using magnetic adsorption

[0010] Turn on the magnetic device on the outer wall of the secondary sedimentation tank and the magnetic grid in the water, and use the magnetic principle to separate the adsorbent from the water. Finally, discharge the purified water to the next step while maintaining the magnetism.

[0011] Beneficial effects:

[0012] The Fe3O4@C@pyridine nanoparticle raw material used in the present invention has good superparamagnetism. It can be quickly aggregated under the action of a magnet and redispersed after the magnet is removed, ensuring that the adsorbent has the advantages of low cost, green environmental protection and reuse. It can be directly added to the sewage treatment process without additional construction. DETAILED DESCRIPTION

[0013] The following examples will enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0014] Example 1

[0015] Traditional sewage treatment plants treat sewage by first passing it through screens (coarse, medium and fine screens, with spacings ranging from 4 to 40 mm) to remove floating objects and small garbage debris in the sewage. Then it passes through a grit chamber to remove some particulate matter in the sewage that has a relatively large specific gravity and is easy to precipitate and separate. It then passes through a primary sedimentation tank to remove the settleable solids in the suspended solids, and some of the non-sinkable floating materials will also be removed through the scum well at the top of the primary sedimentation tank.

[0016] Then it goes through the biological treatment unit, which is the main part of sewage treatment. Most of the pollutants are removed here. Depending on the pollutants to be removed, the process selection here varies greatly. Currently, the AAO process is more widely used, which mainly removes BOD, COD, ammonia nitrogen, total nitrogen, SS, etc., and removes total phosphorus through sludge discharge.

[0017] Then comes the secondary sedimentation tank, which mainly separates mud and water through gravity sedimentation. Part of the sludge is returned to the biological treatment unit, and the excess sludge is treated in the mud area. The supernatant of the secondary sedimentation tank flows out as effluent.

[0018] Add magnetic adsorption material to the secondary sedimentation tank, and pour the superparamagnetic nanoparticle material of Fe3O4@C@pyridine into the secondary sedimentation tank by spreading. Stir to fully absorb microplastics in the water. After fully stirring and absorbing for 3 to 5 minutes, the effect of removing microplastics in sewage is achieved. Use magnetic adsorption to separate the adsorbent from water, turn on the magnetic device on the outer wall of the secondary sedimentation tank and the magnetic grid in the water, use magnetic adsorption to separate the adsorbent from water, and finally discharge the purified water to the next step while maintaining magnetism.

[0019] The effluent from the secondary sedimentation will be subsequently decolorized by ozone, disinfected by chlorine or ultraviolet light according to requirements, and discharged after meeting the effluent standards.

[0020] In summary, the technology used in the present invention can accomplish the task of removing microplastics in sewage treatment plants. The material has superparamagnetism and good dispersibility. It can be aggregated under the action of a magnet and can be dispersed again after the magnet is removed. It can efficiently and quickly adsorb micro-nano plastics and can be reused after desorption treatment. It does not require additional operations for the existing sewage treatment process and can be directly upgraded on the existing technology. Therefore, the material has the advantages of being economical, environmentally friendly, durable, low-cost, and can efficiently adsorb micro-nano plastics in water, providing an effective solution for the repair of micro-nano plastic pollution in water bodies.

[0021] Instruction Manual

[0022] Figure 1 The process of magnetic adsorbents in a wastewater treatment plant.

Claims

1. Based on the application described in the claims, It is characterized in that The specific steps include: Step 1: Fe 3 O 4 @C@Pyridine superparamagnetic nanoparticles are added to the sewage treatment process, and magnetic adsorbents are added to the secondary sedimentation tank container, and stirred and mixed thoroughly; Step 2: Place a magnet on the outer wall of the container and add a magnetic grid to the water, so that the magnetic particles adsorbed by the micro-nano plastics quickly gather on the inner side of the container near the magnet and on the grid; Step 3, maintaining the adsorption effect of the magnet, and discharging the water after removing the micro-nano plastics to the next unit, thereby achieving efficient removal of micro-nano plastics in sewage.

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