Effect Of Rifamycin Mycelial Dreg Treated By Thermally Activated Persulfate And Its Mycelial Dreg Fertilizer On Soil Properties

Antibiotic mycelial dreg is a kind of solid waste with dangerous nature,which is produced during the fermentation of antibiotics production.If it is not timely treatment or improper disposal,it will cause soil,water and other environmental pollution,and even intensify bacterial resistance,endangering human health.The traditional treatment methods of antibiotic mycelial dreg mainly include incineration and landfill.The water content of antibiotic mycelial dreg is high,incineration treatment requires a large number of costs,which brings great economic pressure on the enterprise,seriously limiting the development of pharmaceutical enterprises.Landfill treatment is easy to produce foul odor and cause secondary pollution,which cannot solve the fundamental problem.Rifamycin mycelial dreg,as a kind of antibiotic mycelial dreg with large production volume at present,poses an imminent environmental problem,but rifamycin mycelial dreg is also a valuable resource rich in organic matter and nutrient elements.Based on this feature,a process of thermally activated persulfate oxidation treatment of rifamycin mycelial dreg were established in this study in order to realize the resource utilization of rifamycin mycelial dreg.The effect of rifamycin mycelial dreg fertilizer on soil properties and microbial community structure before and after treatment was investigated in depth by soil culture experiments.In order to accurately assess the residues of rifamycin in mycelial dreg,a method was firstly established for the determination of rifamycin residues in mycelial dreg.After pretreatment of the rifamycin mycelial dreg by solid phase extraction,high performance liquid chromatography(HPLC)was selected for the determination of rifamycin in the mycelial dreg.The optimized solid phase extraction pretreatment conditions were optimized as: acetonitrile as the extractant,acetonitrile/ultrapure water=5:95(v:v)as the drenching agent,5 m L acetonitrile as the eluent;the optimized detection conditions were: acetonitrile/0.1% phosphoric acid water=60:40(v:v)as the mobile phase,and the detection wavelength was 275 nm.The established method was evaluated in terms of precision,detection limit,limit of detection and recovery.The spiked recoveries of rifamycin in mycelial dreg ranged from 88.93% ～ 95.56% with the relative standard deviations(RSDs)of 2.08%～4.67% at the spiked concentrations of 250,500 and 1000 mg/kg,which showed that the method is efficient and accurate for the determination of rifamycin residues in mycelial dreg.The thermally activated persulfate oxidation technique was employed to treat rifamycin in the mycelial dreg,and the degradation efficiency of rifamycin was used as an evaluation index.The reaction conditions were optimized using the response surface method,and the optimal process parameters were determined as follows: reaction temperature 90℃,persulfate dose 50 mg/g,p H 5.3,and the degradation efficiency of rifamycin in mycelial dreg reached 100% within 120 min.The main active species,possible intermediates and degradation pathways of rifamycin were detected by free radical identification experiments and HPLC/ESI/Qq QMS techniques.The soil improvement results of rifamycin mycelial dreg fertilizer showed that compared with the soil with bacterial residue,the application of different proportions of mycelial dreg and mycelial dreg fertilizer could improve soil fertility,but soil p H value decreased.Its application will lead to an increase in the rifamycin content in the soil,but with the extension of the amendment time,the rifamycin content in the soil degrades to the level of the control soil.Sphingomonas,Pseudomonas,Pedobacter,RB41,Flavobacterium,and Bacillus were the dominant bacteria in the soil applied with mycelial dreg and mycelial dreg fertilizer,and the dominant bacteria shared with the control soil were Sphingomonas,RB41,and Bacillus.The abundance of Sphingomonas,Pedobacter and other bacterial genera with the function of degrading organic pollutants and promoting nitrogen decomposition increased in the soil fertilized with mycelial dreg,which was higher than that of the control soil and the soil fertilized with mycelial dreg.And Sphingomonas was significantly negatively correlated with organic matter and total nitrogen,Pedobacter was significantly positively correlated with urease,and Bacillus was significantly negatively correlated with urease.The application of mycelial dreg fertilizer changed some dominant bacterial genus in the soil,promoted soil carbon cycle and nitrogen fixation,promoted the decomposition of soil organic pollutants,and improved.It provides an important theoretical basis and technical support for the resource utilization of rifamycin mycelial dreg.