| In this study,cow manure and corn stover were used as compost materials.The effects of different combinations of bacteria on the composting process of cow manure and the emission trends of related pollution indicators in the composting process were investigated by further adding different exogenous agents.The number of various microorganisms(bacteria,fungi,actinomycetes)changes regularly.In this way,the best combination of bacteria is determined to provide effective data support for the treatment of cattle waste.The test was divided into 3 composting treatment groups(3 replicates per treatment)and 1 control group,of which treatment group 1 was cow dung(70%)+corn stover(30%)+compound microbial agent 1(Bacillus subtilis+Streptomyces fulvus;treatment group 2 was cow dung(70%)+corn stover(30%)+compound microbial agent 2(Trichoderma reesei+Streptomyces fulvus);treatment group 3 was cow dung(70%)+corn stalk(30%)+compound microbial agent 3(Bacillus subtilis+Trichoderma reesei+Streptomyces fulvus);the control group is cow dung+corn stalk.The three treatment groups were each added with a 0.1%(by mass)composite microbial agent,and the control group was not added with a microbial agent.Fertilizer efficiency index,conventional index,toxicity index,concentration of copper(Cu)and zinc(Zn),ammonia(NH3)and carbon dioxide(CO2)in the fermentation process of cow manure and bacteria and fungi of the heap were carried out.The number of actinomycetes was studied.The results are as follows:The effects of different combinations of strains on the aerobic composting process of cow manure showed that in the process of composting,adding different exogenous microorganisms can increase the duration of high temperature period;accelerate the evaporation of water in the heap;have no obvious influence on the change of pH.The nitrogen content and total nutrient content of the heap are obviously improved;the organic matter is effectively promoted,and the relative content of total phosphorus and total potassium is increased;the total nutrient content in the seed germination index is significantly improved;Effectively increase the seed germination index of compost materials.By analyzing the changes of various indexes in the compost,the composting effect of the composite microbial agent 2(Trichoderma reesei+Streptomyces fulvus)was the best in this study.The effects of different combinations of bacteria on the changes of Cu and Zn concentrations during the composting of cattle manure showed that at the end of composting,the total copper content of each group increased by 2.28 mg/kg,0.65 mg/kg,2.95 mg/kg,respectively,3.29 mg/kg.The total zinc content of each group was:116.70 mg/kg,121.47 mg/kg,123.50 mg/kg,At 123.80 mg/kg,treatment groups 1 and 2 were reduced by 5.2 mg/kg and 0.43 mg/kg,respectively,and treatment group 3 and control group were increased by 1.6 mg/kg and 1.9 mg/kg,respectively.The exogenous microorganisms added in this study can effectively reduce the increase in the concentration of heavy metals Cu and Zn in the compost.Among them,treatment group 2(Trichoderma reesei+Streptomyces fulvus)had the least increase in Cu,and treatment group 1(Bacillus ssubtilis+Streptomyces fulvus)had the least increase in Zn,and the effect was remarkable.The effects of different combinations of bacteria on ammonia and carbon dioxide emissions during the composting of cattle manure showed that on the 5th day of composting,the ammonia concentration of each group reached the peak,which was 380.00 ppm,406.00 ppm,325.00 respectively.471.6 ppm.Among them,the ammonia concentration of the control group was the largest,and the treatment group 3 was the smallest.On the 7th day of composting,the carbon dioxide concentrations of treatment group 2 and treatment group 3 peaked at 2.68 × 104 ppm and 3.05 ×104 ppm,respectively.On the 9th day of composting,treatment group 1 and control group peaked at 3.06 ×104 ppm,3.57 ×104 ppm.The control group had the highest concentration of carbon dioxide release and the treatment group had the smallest.It shows that the addition of exogenous microbial strains can significantly reduce the release concentration of ammonia and carbon dioxide,reduce the emission of harmful gases,and reduce the emission reduction effect.Among them,treatment group 3(Bacillus subtilis+Trichoderma reesei+Streptomyces fulvus)had the best effect.The effects of different combinations of microbial strains on the changes of bacteria,fungi and actinomycetes during the composting process of cow manure showed that the number of bacteria in the treated group was significantly higher than that in the control group during the whole composting process.They are:1.56×1010 copies/g,1.96×1010 copies/g,2.42 ×1010 copies/g,1.55×1010 copies/g,indicating that the addition of exogenous bacteria can increase the number of bacteria,effectively improve the decomposition and maturity of compost materials.Among them,treatment group 3(Bacillus subtilis+Trichoderma reesei+Streptomyces fulvus)has the best effect;During the whole composting process,the number of fungi in the treated group was significantly higher than that in the control group.At the end of composting,they were:24.8 ×107 copies/g,56.1×107 copies/g,92.2 ×107 copies/g,51.9×107 copies/g,which shows that the addition of exogenous bacteria increased the number of fungi,which is conducive to the decomposition and decomposing of compost materials.Among them,treatment group 3(Bacillus subtilis+Trichoderma reesei+Streptomyces fulvus)has the best effect;During the whole composting process,the number of actinomycetes in the treated group was significantly higher than that in the control group,and at the end of composting,they were:23.8×108copies/g,37×108 copies/g,38.5 ×108 copies/g,30.5 ×108copies/g,in which treatment group 2(Trichoderma reesei+Streptomyces fulvum)and treatment group 3(Bacillus subtilis+Trichoderma reesei+Streptomyces fulvus)had the best effect.Aerobic composting is one of the effective ways to make harmless and resourceful treatment of livestock manure.According to the above research,it is considered that the addition of Trichoderma reesei+Streptomyces fuliginea in cow dung has the best effect on fertilizer efficiency,environmental impact and microbial quantity change. |
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