Effects Of Municipal Sludge Biochar On Composting Of Swine Manure And Degradation Of Oxytetracycline

In China,the treatment and disposal of municipal sludge and livestock manure are increasingly prominent problems in the current environmental field.However,it can better achieve harmless,stable and resource recovery of both that municipal sludge biochar(MSB)or magnetically modified municipal sludge biochar(MMSB)composted with livestock manure.At the same time,due to the existence of serious antibiotic residues in livestock manure,and the resistance genes(ARGs)will spread between different microorganisms by returning to the field and pose serious threats to human health and environmental safety.In view of the fact that there are still limited studies on the effects of MSB and MMSB on the composting effect of livestock manure and antibiotics and ARGs,and relevant work was carried out in this paper.Firstly,the influence of heap size and aeration conditions on the physical and chemical properties of pig manure composting was discussed by means of control variable method,and a 0.50×0.50×0.40 m trough heap model and intermittent aeration method were determined,which can obtain better composting quality.Secondly,3 kinds of MSB(MSB-300,MSB-500,MSB-700)prepared by different temperature conditions,and 2 kinds of MMSB(MMSB-0.1,MMSB-0.25)prepared by different modifier concentrations were composted with swine manure,according to the applied ratio of 0,5%,10% of swine manure(dry weight),respectively,the results showed that: both MSB and MMSB can promote the heap of body temperature and heat preservation,in which the MSB-700 and MMSB-0.1 had better heat preservation effect,theirs peak temperature were higher than the control group by 3.3 ℃,days over 60℃were more by 5 days;the MSB-700 group with 10% addition has the best composting effect,and its DOC and VS degradation rates were higher than the control group with3.17% and 396%,respectively;adding 5% MSB can promote fertilizer rot,but adding10% will inhibit rot.Finally,by tracking the content of Oxytetracycline(OTC)in the composting process,it was found that MSB can promote OTC degradation,while MMSB can complexate with OTC,which was no conductive to OTC degradation.Adding 10% of MSB-500 can promote the degradation of tet B and tet M in ARGs,but it is not conducive to the degradation of tet C gene because MSB promotes the growth and propagation of microorganisms(Cellvibrio and Steroidobacter)which carried tetc,and that also amplified to tet Q.In addition,it was found that ARGs were greatly affected by DOC,temperature and p H by the means of redundant analysis.DOC,temperature and moisture content played an important role in the early stage,and p H played an important role in the later stage.From the perspective of manure fertilization and agricultural suitability,MSB has some applicability to pig manure composting with low concentration of OTC.