Construction Of Solid Composite Inoculum For Green Waste Degradation And Its Effect On Composting

In recent years,greening career was in the stage of rapid development in China,the level of urban green has been continuously improved,at the same time,it also led to the yield of green waste increased year by year.Technologies like composting can realize the recycling of green waste.Previous studies have shown that utilization of microbial inocula is one of the effective method to promote the composting of green waste.In order to obtain high efficiency degradation of green waste solid composite inoculum and speed up the composting process,this study aims to isolate high-efficiency lignin and cellulose degrading microorganisms from green waste composting,And the solid microbial inoculum was prepared by optimizing some common technological parameters such as medium,protectant,and inoculum concentration in the solid fermentation process.On this basis,the proportion and concentration of which were optimized using an orthogonal experiment to develop the solid composite inoculum,and the promotion effect of the microbial inoculum on green waste composting was evaluated.The specific experimental results are as follows:（1）Two high-efficiency degrading strains B01 and B02 were screened from the decomposed compost using the selected medium,and both of them from Bacillus sp.The optimum conditions for solid-state fermentation of B01 was 35%of wheat bran,45%of rice bran,6%of lactose,6%of soybean flour,and 8%of diatomite;the bottling quantity was 15%,the inoculum concentration was 15%,the ratio of materials to water was 1:1 and the protectant used was 5%of trehalose.The aforementioned optimizations reached the bacterial colonies of B01 in the solid inoculum to 2.62×10¹⁰CFU/g（calculated by dry base）.The optimum conditions for solid-state fermentation of B02 was 25%of wheat bran,50%of rice bran,7%of lactose,7%of soybean flour,and 11%of diatomite;the bottling quantity was 20%,the inoculum concentration was 20%,the ratio of materials to water was 1:1 and the protectant used was 2%of Tween 80.The aforementioned optimizations reached the bacterial colonies of B02 in the solid inoculum to 9.5×10⁹CFU/g（calculated by dry base）.Compared with before optimization,the activities of the two solid microbial inoculum were significantly improved.（2）After being stored in-4℃for half a year,the bacterial colonies of B01 and B02 in the solid inoculum to 1.03×10¹⁰CFU/g and 4.3×10⁹CFU/g.The survival rate of solid inoculum B01 was 63.46%higher than that of liquid inoculum B01,and the survival rate of solid inoculum B02 was 67.13%higher than that of liquid inoculum B02.After being stored in 25℃for half a year,the bacterial colonies of B01 and B02 in the solid inoculum to 7.43×10⁹CFU/g and 2.97×10⁹CFU/g.The survival rate of solid inoculum B01 was 532.37%higher than that of liquid inoculum B01,and the survival rate of solid inoculum B02 was 466.79%higher than that of liquid inoculum B02.These results indicated that the number of bacterial colonies of solid inoculum B01 and B02 could meet the standard of《Biological Organic Fertilizer》,and the survival rate was higher than that of liquid microbial inoculum.（3）It was found through orthogonal experiment that both factors had significant influences on functions of the composite inoculum,in which the proportion of B01 and B02 had greater influences than the concentration.The proportion（B01:B02）of 7.5:2.5,and concentration of 2.5%constituted the composite inoculum with the optimal functions,and the optimal functions was named SB012.Under these conditions,the synergistic effect between strains could exert the maximum effect,and the degradation rate of lignin and cellulose could be significantly improved.（4）The results of composting experiment showed that the addition of SB012 to compost significantly increased the degradation rate of organic matter,which was conducive to the conversion of lignocellulosic materials into humus precursors,promoting the synthesis of humus,improving the humification level of compost,and improving the composting aging efficiency.Compared with the EM,utilization of the SB012 during green waste composting increased the lignin degradation rate by 19.57%,cellulose degradation rate by 6.67%,and humus content by 7.31%;Compared with the liquid composite inoculum,utilization of the SB012 during green waste composting increased the lignin degradation rate by 7.79%,cellulose degradation rate by 5.30%,and humus content by 6.29%.In addition,the composite inoculum could also adjust the p H and EC in the process of composting,improve the quality of compost products,realize non-toxic and harmless.