Effects Of Different Hydrogen Peroxide Systems On Carbon Conversion And Pollution Control And Functional Microbiome During Composting

With the rapid development of agriculture in China,a large amount of livestock manure and straw waste are produced annually,which would cause serious environmental pollution if not handled properly.To make the resource utilization of agricultural wastes,composting as an environmentally friendly technology can be widely used in the treatment organic solid wastes.However,the degradation rate of recalcitrant lignocellulose was slow in traditional composting,which was a limiting factor in the composting process.In this paper,effects of different hydrogen peroxide systems on the lignocellulose degradation,humification degree and microflora in composting were studied from the perspectives of microbe and inorganic chemical reaction.The purpose of this study was to investigate the effects of different hydrogen peroxide systems on the physicochemical characteristics,organic matter deconstructions,humic substance formation,bacterial community succession and pollution control in composting.The effects of adding H₂O₂and ascorbic acid（ASCA）for promoting the activity of lytic polysaccharide monooxygenases were studied in co-composting of bagasse pith and dairy manure.The results indicated that H₂O₂and ASCA accelerated the degradation of lignocellulose,improved the transformation of dissolved organic matter,enhanced the content of humic substance and its aromatization degree in composting.The hydrogen peroxide system significantly changed the bacterial community and provided a more favorable microbial system for lignocellulose degradation,in which the relative abundances of Firmicutes and Actinobacteria significantly increased.Redundancy analysis indicated that the degradation of organic matter and lignocellulose had a great impact on bacterial community compositions.Adding H₂O₂ and Cu Cl in co-composting of sawdust and dairy manure was to investigate the occurrence of the Fenton-like reaction in composting,and was to explore the impacts of the Fenton-like reaction on humic substance formation mechanism and functional microbial communities during composting.The results indicated that the Fenton-like reaction was beneficial to the formation of hydrogen peroxide and hydroxyl radicals in composting.The activity of laccase（35.92 U/g）and the content of humic substance（151.91 g/kg）under the Fenton-like reaction condition were significantly higher than that in the control of 29.56 U/g and131.73 g/kg.Additionally,the Fenton-like reaction significantly promoted amides,quinones,aliphatic compounds and aromatic compounds to form humic substance by 2D-FTIR-COS analysis.Metagenomic analysis showed that Proteobacteria contributed most greatly to Auxiliary Activity 1（AA1）at phylum level,the Fenton-like reaction increased the abundances of Pseudomonas and Sphingomonas in composting.Redundancy analysis indicated that there was a strong positive correlation among the Fenton-like reaction,laccase and humic substance,indicating that the Fenton-like reaction could enhance the laccase activity and promote the humic substance formation in composting.To investigate the effects of the Fenton-like reaction on the changes of heavy metals speciation,the abundance changes of antibiotic resistance genes（ARGs）and the contribution degree of host bacteria carrying ARGs in composting.The results showed that Fenton-like reaction promoted the passivation of Zn,Ni and Mn,inhibited the increase of relative abundance of bacitracin resistance genes,and increased the contribution of Proteobacteria to bacitracin,tetracycline and aminoglycoside resistance genes during composing.Redundancy analysis showed that the passivation of heavy metals in composting contributed to the removal of tetracycline,macrolides-lincosamids-streptogramins and aminoglycoside resistance genes,but had little effect on bacitracin and sulfonamides resistance genes.Conclusively,two hydrogen peroxide systems could accelerate the degradation of lignocellulose,change the microbial community structure,enhance the activity of lignocellulose degradation enzyme,promote the formation of humic substance and control the harm of pollution,so as to improve the quality of compost,which provided reference to dispose of lignocellulose wastes and livestock manure.