An antibiotic removal method using struvite as a carrier during phosphorus recovery from biogas slurry.

Abstract

This invention relates to a method for antibiotic removal using struvite as a carrier during phosphorus recovery from biogas slurry, belonging to the field of water pollution control and resource regeneration. The method involves: firstly, recovering nitrogen and phosphorus from biogas slurry using struvite crystallization. The initial pH of the biogas slurry is adjusted to 8.0-10.5, and the mixture is thoroughly stirred. A certain amount of magnesium source is added to initiate the struvite crystallization reaction. Simultaneously, a certain amount of persulfate PMS oxidant is rapidly added, and the reaction pH is adjusted to 8.0-10.5. The mixture is stirred evenly, and the reaction time is controlled at 20-90 minutes, effectively removing antibiotics from the biogas slurry. This invention, while ensuring a high yield of struvite recovery from biogas slurry, accelerates electron transfer rates through struvite crystallization, improving the efficiency of PMS degradation of antibiotics. It provides a simple and effective method to reduce the ecological risks caused by antibiotics during biogas slurry struvite recovery.

Description

Technical Field

[0001] This invention belongs to the field of water pollution control and resource recycling, and is a method for antibiotic removal using struvite as a carrier during biogas slurry phosphorus recovery. Background Technology

[0002] With the increasing depletion of global phosphate rock resources, the shortage of phosphate fertilizer has posed a serious threat to food production, and the "phosphate crisis" has become one of the most pressing issues facing human society today. Among numerous phosphate recovery technologies, the struvite (MgNH4PO4·6H2O) crystallization method is a highly efficient and feasible method for phosphate resource recovery. It not only features rapid reaction rates and excellent phosphorus removal effects, but the recovered product can also be used directly as a highly efficient slow-release fertilizer in agricultural production. In recent years, my country's livestock and poultry farming industry has developed rapidly and become highly intensive. This has led to a sharp increase in the discharge of livestock and poultry wastewater, putting enormous pressure on my country's environment. However, livestock and poultry biogas slurry is rich in nutrients such as nitrogen and phosphorus, representing a vast treasure trove of nitrogen and phosphorus resources. By recovering struvite from livestock and poultry wastewater, we can not only achieve the sustainable utilization of nitrogen and phosphorus resources but also effectively reduce the problem of excessive nitrogen and phosphorus content in wastewater.

[0003] Veterinary antibiotics are widely used in livestock and poultry farming to prevent and treat animal diseases and promote animal growth. Because veterinary antibiotics are difficult for animals to absorb, most are excreted into livestock and poultry wastewater in the form of feces or urine. Continuous exposure to antibiotics in the environment can lead to the spread of antibiotic resistance genes in water, soil, and other media, posing health risks to humans and the ecological environment. Therefore, when struvite recovered from livestock and poultry biogas slurry is used in agriculture, it can exacerbate the spread of antibiotic resistance in the food chain, thus threatening human health. This makes antibiotic residues during the recovery of struvite from livestock and poultry biogas slurry an unavoidable and important issue in its resource utilization. Therefore, exploring methods to control antibiotic pollution during struvite recovery can help mitigate the health and safety risks caused by antibiotic migration during the process.

[0004] Persulfate non-radical oxidation can selectively attack electron-rich groups found in most antibiotics, such as amino, hydroxyl, aromatic rings, and alkenes. This method improves the utilization efficiency of the oxidant to effectively remove pollutants while avoiding the negative impacts of blindly applying advanced oxidation technologies, such as avoiding the generation of halogenated byproducts. It is suitable for the degradation of trace pollutants such as antibiotics in complex biogas slurry environments. Persulfates include peroxymonosulfate (PMS) and peroxydisulfate (PDS). Due to its asymmetric structure, PMS is more likely to directly oxidize organic pollutants through electron transfer under unactivated conditions. Furthermore, under alkaline conditions, antibiotics are negatively charged and readily adsorb onto the Mg[H2O]6 of struvite.2+ On the crystal surface, struvite crystals act as a carrier, promoting electron transfer and inducing PMS non-radical degradation of antibiotics. Therefore, this invention provides a method for removing antibiotics during struvite crystallization in livestock and poultry wastewater, which can reduce the risk of antibiotic pollution and has significant application value for the resource utilization of livestock and poultry wastewater. Summary of the Invention

[0005] To address the issue of antibiotic diffusion and spread in the environment during the recovery of livestock and poultry biogas slurry using struvite, this invention presents a method for antibiotic removal using struvite as a carrier during phosphorus recovery from biogas slurry. The method involves the following steps: First, nitrogen and phosphorus in the biogas slurry are recovered using struvite crystallization. The initial pH of the biogas slurry is adjusted to 8.0-10.5, and the mixture is thoroughly stirred. A certain amount of magnesium source is added to initiate the struvite crystallization reaction. Simultaneously, a certain amount of PMS oxidant is rapidly added, and the reaction pH is adjusted to 8.0-10.5. The mixture is stirred evenly, and the reaction time is controlled at 20-90 minutes, effectively removing antibiotics from the biogas slurry. This invention, while ensuring a high yield of struvite recovery from biogas slurry, accelerates electron transfer rates through struvite crystallization, thereby improving the efficiency of PMS in degrading antibiotics. This provides a simple and effective method to reduce the ecological risks caused by antibiotics during the struvite recovery process.

[0006] Project Implementation Plan

[0007] Example 1: A pig farm wastewater slurry had an initial pH of 7.6 and contained 500 μg / L of tetracycline. First, the initial pH of the slurry was adjusted to 9.0, and after thorough stirring, a certain amount of magnesium source was added to initiate a struvite crystallization reaction. Simultaneously, 0.2 mM PMS oxidant was rapidly added, and the reaction pH was adjusted to 9.0. The mixture was stirred evenly, and the reaction time was controlled at 45 min. After the reaction, the residual concentration of tetracycline in the wastewater was measured to be 1.80 μg / L, with a tetracycline removal rate of 99.6%.

[0008] Example 2: A pig farm wastewater sample had an initial pH of 7.2 and contained 1000 μg / L of oxytetracycline. First, the initial pH of the wastewater was adjusted to 9.5, and the mixture was thoroughly stirred. A certain amount of magnesium source was added to initiate the struvite crystallization reaction. Simultaneously, 0.5 mM PMS oxidant was rapidly added, and the reaction pH was adjusted to 9.5. The mixture was stirred evenly, and the reaction time was controlled at 30 min. After the reaction, the concentration of oxytetracycline in the wastewater was measured to be 26.0 μg / L, with a removal rate of 97.4%.

Claims

1. A method for antibiotic removal with struvite as a carrier during phosphorus recovery from biogas slurry, characterized by The method steps are: first, applying struvite crystallization method to recover nitrogen and phosphorus in biogas slurry, adjusting the initial pH value of the biogas slurry to 8.0-10.5, fully stirring, adding a certain amount of magnesium source to carry out struvite crystallization reaction, at the same time, quickly adding a certain amount of peroxymonosulfate (PMS) oxidant, adjusting the reaction pH value to 8.0-10.5, stirring uniformly, and controlling the reaction time of struvite crystallization and PMS oxidation to be synchronous in 20-90 min, so that the antibiotics in the biogas slurry can be effectively removed.