Efficiency Of Erythromycin Fermentation Residue Treated With Persulfate And Effect Of Residue Fertilizer On Soil Performance

Antibiotic fermentation residue（AFR）is a by-product of antibiotic fermentation process.It contains a lot of nutrients.The residual antibiotics will cause potential environmental risks and human health risks by causing bacterial resistance,so its treatment is urgent.However,its high treatment and disposal cost seriously limits the development of China’s pharmaceutical industry,and it is urgent to develop appropriate treatment and disposal technology.Considering that erythromycin fermentation residue（EFR）is in rich in organic matters,erythromycin（ERY）has stable structure and is difficult to biodegrade,ERY-resistant genes remain in EFR,as well as high water content（about 90%）and low calorific value lead to high incineration cost and secondary pollution,the heat-activated persulfate（PDS）treatment of EFR was established.The removal of ERY,the inactivation of ERY-resistance genes and the dewatering of EFR were investigated.In addition,EFR after treatment was used as a fertilizer.The environmental risks of the reutilization of EFR were evaluated.This research provides theoretical basis and engineering practice support for the harmless treatment and resource utilization of EFR.Heat-activated PDS oxidation of EFR was developed to degrade the residual ERY and inactivate the ERY-resistant genes.The effects of temperature（25-90℃）,initial PDS concentration（0-50 g PDS/kg EFR）,and p H（3.00-10.50）on the removal of ERY in EFR were studied.The results revealed that 99.0%ERY was degraded by 25 g PDS/kg EFR under 80°C within 120 min.The apparent rate constant(k_app)in the acidic condition was higher than that in the alkaline condition.Sulfate radical(SO₄^·–)played an important role in the removal of ERY from EFR.Six intermediate products（IPs）of ERY were clarified.The detected ERY-resistant genes ere B,erm A,and erm B obviously presented a reduction during the heat-activated PDS oxidation process,and they were not detected at the end of the reaction.Heat-activated PDS treatment is more economically feasible than traditional incineration treatment.The objective of this chapter is to investigate the role and mechanism of heat-activated PDS oxidation conditioning on EFR properties and how these variations influence EFR filtration dewaterability.Results indicated that EFR dewaterability was worse under single heat process（80℃）,but significantly improved under heat-activated PDS oxidation process（80℃,50 g PDS/kg EFR）.Heat-activated PDS oxidation conditioning could destroy mycelium cells,promote the release of soluble chemical oxygen demand,total nitrogen,ammonia-nitrogen,nitrate-nitrogen,total phosphorus,orthophosphate and organic phosphorus,as well as the decomposition of soluble chemical oxygen demand,organic nitrogen and organic phosphorus.Heat-activated PDS oxidation conditioning was capable to increase zeta potential and reduce median particle size.Concurrently,heat-activated PDS oxidation conditioning resulted in the decrease of protein in tightly bound（TB）extracellular polymeric substances（EPS）and total EPS,and the decrease of fluorescing constituents（tryptophan protein,tyrosine protein and tryptophan amino acid）in EPS.Furthermore,a possible mechanism was proposed for heat-activated PDS oxidation conditioning.A laboratory soil incubation experiment was performed to investigate the effects of EFR fertilizer on soil physicochemical properties,microbial activity and soil safety.The results indicated that p H in treated EFR-amended soil decreased firstly and then increased.The salinity of soil increased but soil was still non-saline soil.The content of organic carbon and organic nitrogen in the EFR-amended soil was higher than that in the control group,and the content of both showed a decreasing trend.The biodegradability of EFR was improved after oxidation treatment.In addition,the introduced ERY（6.16 mg/kg）decreased by94.08%during the treated EFR-amended soil incubation process and its half-life was 12.3 d.Moreover,the relative abundances of ERY resistance genes and MGEs in the treated EFR-amended soil were much lower than those in the control at the end of incubation.Bacterial community structure in the treated EFR-amended soil converged to similar structure in control soil after 49 d incubation.Our results showed that heat-activated PDS oxidation treatment of EFR prior to application to soil might be in favor of limiting the spread of ERY resistance genes and MGEs,making the use of EFR fertilizer have a higher safety.