Investigation The Effect Of Biochar Based Microbial Inoculation On Pig Manure Aerobic Composting Rergulation

For the traditional static aerobic composting system,the disadvantages such as large amount of greenhouse gases emissions,serious nitrogen loss,and low efficacy in organic matter degradation,etc.,often results in poor compost product quality and unignorable environment pollution,and thus limits the large-scale engineering application.The aerobic composting process is a biochemical reaction which is mediated by the activities of microorganisms.How to scientifically promote the composting materials’biological stabilization process is the key point of improving the quality of compost product and the efficiency of engineering composting practice.In order to declare the regulation effect of biochar/microbial inoculation additive on pig manure composting biological stabilization process.In this study,pig manure as selected as raw compost material,sawdust was used as bulking agent,biochar（BC）,microbial inoculation（MI1 and MI2）,and carbon based biological inoculation（biochar/microbial floc complex BCMI1 and BCMI2）were employed as compost additives,respectively.All the compost mixtures were aerobic composted in a serial of self-designed dynamic aerobic composting reactors for 42days.The compost parameters like temperature,pH,total organic matter（TOC）,dissolved organic matter（DOC）,CO₂,CH₄,N₂O,NH₃,ammonium（NH₄⁺-N）,nitrate（NO₃^--N）,total Kjeldahl nitrogen（TKN）,volatile fatty acids（VFAs）and the microbial community diversity,etc.were monitored accordingly.The main results of this study were summarized as below.（1）During the 42-day aerobic composting,all the treatments meet the requirements of composting harmlessness and compost maturity.The durations of thermophilic stage of BC,MI1,MI2,BCMI1,and BCMI2 treatment were 11,10,8,12,and 9 days,while the control treatment was only 6 days.After composting,the final pH values of all treatments were in a satisfied range（pH 8.05⁸.30）;the TOC content of the control,BC,MI1,MI2,BCMI1,and BCMI2 treatments was 39.68,38.35,37.38,38.17,36.20 and 36.61%,respectively.Addition of additives like BC,MI1,MI2,BCMI1,and BCMI2 prolonged the duration of thermophilic phase and improved the degradation of organic matter.（2）In the 42-day composting,the emissions of CO₂,CH₄,N₂O and NH₃occurred in the first two weeks of composting.Compared to control,the release of N₂O in the BCMI1 and BCMI2 treatments was reduced by 29.00%and 22.14%,respectively;the volatilization of N₂O inMI1 and MI2declined by 16.95%and 16.98%,respectively.Moreover,the BC amendment reduced the productions of CO₂ and CH₄,while other treatments improved the CO₂ and CH₄ generation.During the composting process,the NH₃cumulated amount was in order of control（8.01 g）>BC（6.46 g）>MI2（4.42 g）>MI1（4.06 g）>BCMI2（2.94 g）>BCMI1（2.36 g）,and the N₂O cumulated amount was in order of control（1.31 g）>MI2（1.10g）>MI1（1.08 g）>BCMI2（1.02 g）>BCMI1（0.93 g）>BC（0.79 g）,indicating all the treatments had great potential on N₂O and NH₃ emission reduction besides control,especially the BCMI1 and BCMI2 treatments.（3）After 42 days of composting,the concentration of NH₄⁺-N of all treatment was lower than 0.40 g kg^?1with a satisfied maturity;in treatment of Control,BC,MI,and BCMI,the content of NO₃^--N reached 0.82,1.09,1.20 and 1.23 g kg^?1respectively,and the content of TKN increased by 31.80,38.06,48.90,42.25,59.06 and 54.25%,respectively,proving MIor BC or biochar/microbial floc（BCMI1 and BCMI2）addition favors nitrogen conservation.（4）Amendment of the compost mixture with the selected additives improves the degradation of VFAs.The decline of VFAs concentration of all treatments matches the pseudo-first-order kinetic model with the obtained constant of reaction rate k in values of0.077,0.099,0.078,0.081,0.078 and 0.092 d^-1 for control,BC,MI1,MI2,BCMI1 and BCMI2 treatment,respectively,suggesting addition of BC,MI2 or BCMI2 into the compost mixture was more favorable to the degradation of VFAs during composting than other additives.Compared with other treatments,BCMI1 and BCMI2 treatments significantly increased the abundance and diversity of bacterial communities during composting.In addition to bacterial communities of Proteobactia,Firmicutes and Actinobactenia,the abundance of communities such as Bacteroidetes and Tenericutes were significantly increased as well.Moreover,the number of OTUs in the two treatments was approximately1030 and 1058,which were significantly higher than that of the control treatment（596）.（5）The use of the biochar based microbial inoculation（BCMI1 and BCMI2）not only reduces greenhouse gases emission,improves the composting of nitrogen conservation,accelerates the VFAs degradation,and increases the abundance and diversity of bacterial communities,but also improves the quality of final compost product.After 42 days of composting,the final compost product of the four treatments exhibited acceptable fertilizer potential in agriculture,especially the BCMI1 and BCMI2 added treatments show a synergistic effect on pig manure composting enhancement.The developed biochar based microbial floc is a promising compost additive has great potential in composting engineering practice.