Effects Of Powder Biochar And Particle Biochar On Aerobic Composting Of Pig Manure

Aerobic composting can effectively deal with the excrement produced in the process of livestock and poultry breeding,but in the process of aerobic composting of livestock and poultry manure,there are still widespread shortcomings such as secondary pollution of the composting process,low maturity of composting,and weak passivation ability of heavy metals.Therefore,how to effectively reduce the secondary pollution in aerobic composting process,improve the degree of maturity and heavy metal passivation is the main purpose of this study.In this study,pig manure was used as compost substrate,sawdust was used as exogenous regulator,and biochar with different particle sizes was added as exogenous additives.The effects of adding biochar with different particle sizes on the conventional physical and chemical parameters of pig manure aerobic composting and on the release of greenhouse gases and ammonia in composting were studied.The effects of adding biochar with different particle sizes on the evolution of water-soluble organic compounds were studied by means of spectroscopy.The changes of heavy metal morphology by adding biochar with different particle sizes were studied.Through the above studies,the influence of biochar with different particle sizes on pig manure aerobic composting was comprehensively evaluated,which has guiding significance for the practical application of biochar in improving composting process and agricultural utilization of the products.In order to investigate the effect of biochar with different particle sizes on pig manure aerobic composting,three groups of experiments were designed.In the second group,500 g 200 mesh biochar(PB)was added.In the third group,500 g 10 order biochar(GB)was added.It was found that the addition of particle biochar could increase the porosity of the pile,improve mass transfer,extend the high-temperature period of the compost,and enhance the water-holding capacity.While the powder biochar could accelerate the early-stage warming,but promote the water volatilization and reduce the water content.The addition of biochar could reduce the nitrogen loss in the composting process.the cumulative emission of ammonia gas with the granular biochar was reduced.The addition of biochar reduced the global warming potential of composting,but compared with the control group,powder biochar increased methane emission,and granular biochar increased nitrous oxide emission.It is found that biochar,especially granular biochar,can effectively promote the utilization of dissolved carbon and nitrogen by microorganisms in the compost.It was found that composting improved the degree of macromolecule polymerization and humus stability of water-soluble organic compounds.The results of three-dimensional fluorescence regional integration showed that with the progress of composting reaction,the content of humus and other biodegradable organic matter decreased continuously,among which the addition of granular biochar promoted the formation of humus most obviously.It was found that dissolved organic compounds contained three fluorescent components by three-dimensional fluorescence spectrofluorimetric coupled parallel factor analysis(EEM-PARAFAC).Among them,C1 and C2 represented humus-like and acid-like substances and were related to macromolecular aromatic organic compounds.The C3 group was related to protein-like substances.The degradation rates of C3 components in CK,PB and GB groups were 70.15%,65.39% and 70.41%,respectively,indicating that the addition of granular biochar could promote the decomposition of organic matter in materials and accelerate the process of decomposition.After studying the morphological changes of heavy metals in pig manure composting,it was found that the addition of large-particle biochar was beneficial to the passivation of copper in the composting process,while small-particle powder biochar was not beneficial to the passivation of copper,and the passivation of zinc was not obvious under different treatments.After analyzing the correlation between different indexes,it was found that heavy metal passivation was significantly related to composting maturity and p H,and large particle biochar could accelerate composting maturity and promote the passivation of heavy metals in materials.