Research On Resource Utilization Of Biogas Fermentation Liquid For Livestock And Poultry Wastewater

How to realize the rational resource utilization of biogas slurry at low cost has always been a serious problem in the construction and operation of large and medium-sized biogas projects.In this study,aerobic stabilization of biogas slurry was carried out using a self-developed“multi-stage continuous aerobic fermentation process”.Detailed research was carried out on the process conditions,biosafety,stabilization of the biogas slurry and straw co-processing,and functional components of the stabilized biogas slurry in the stabilization biogas slurry treatment process.Firstly,aerobic treatment of biogas slurry forms a“multi-stage aerobic biogas slurry stabilization process”by inoculating functional microorganisms on the basis of the“multi-stage continuous aerobic fermentation process”.The results show that the optimal hydraulic retention time of aerobic treatment of biogas slurry is 17d,which is much lower than 90d that stabilization time of the traditional oxidation pond;the NH₄-N in the biogas slurry was reduced by 68.68%;Stabilized biogas slurry has a low degree of aromatization and carbonyl condensation,a high degree of humification,and contains high trace elements required for plant growth and development such as Si and K.The microbial hygiene indicators in the stabilized biogas slurry meet the national fertilizer sanitation standards,and the stabilized biogas slurry is stable in nature and can be preserved for a long time,with further productization conditions.Secondly,in order to investigate the biosafety of stabilized biogas slurry,the stabilized biogas slurry was used to test the seed germination of corn,rice and soybean seeds respectively in this study.The results showed that the germination rate of corn,rice and soybean was 54.67.%,94.00%,94.67%,reached the standard for biosafety of fertilizers.Moreover,compared with the control group?CK?,the germination percentage and germination potential of corn were increased by 26.66%and 20%respectively when the stabilized biogas slurry was diluted 200 times and then the corn was immersed in seed soakingthe;The germination effect of rice and soybean was the best after dilution of 500times.Compared with the clear water control group?CK?,the germination rate and germination potential of rice increased by 7.34%and 8.67%respectively,and the germination rate and germination potential of soybean seeds increased by 8%and 8.66%.The seedlings of the three crops were homogeneous,the roots were strong,and the chlorophyll content of seedling leaves increased significantly.The above results show that the stabilized biogas slurry has high biological activity.Thirdly,this study also investigated the way of stabilized biogas slurry and corn stalks combined with the field.In order to compare the biofunctionality of the stabilized biogas slurry,this experiment uses a commercially available straw rot fungus?including EM bacteria?for comparison.The experimental results showed that the efficiency of straw degradation was significantly improved?p<0.05?when the stabilized biogas slurry was applied in the process of returning corn stalks to the field compared with the control group and the biogas liquid application group;Compared with the control group,biogas slurry raw liquid and commercial fungicide application group,the soil alkaline nitrogen,available phosphorus,available potassium and organic matter nutrient contents in the stabilized biogas slurry group were significantly increased?p<0.05?;Compared with the control group,the activities of soil enzymes in the stabilized biogas slurry experimental group were significantly higher than those in the control group?p<0.01?,and the activities of soil enzymes in the stable biogas slurry experimental group were significantly higher than those in the biogas slurry original slurry group and the commercial microbial agent application group?p<0.05?.The above experimental results show that the stabilized biogas slurry has high biological activity and functionality.Finally,this study conducted a more in-depth mechanistic study on the bioactivity and functionality of stabilized biogas slurry,which comprehensively analyzed the changes in active components of the“multi-stage aerobic biogas slurry stabilization process”during the biogas slurry treatment process.Correlation analysis showed that the total C and N elements of soluble materials gradually decreased and eventually stabilized during the stabilization of biogas slurry,and the content of phenolic hydroxyl functional groups increased gradually,indicating that more active functional groups were produced in the process of biogas slurry stabilization;the results of UV and FT-IR spectroscopy indicate that the stabilization products of biogas slurry contain a large number of fulvic acid-like substances.Fulvic acid has strong chelation,conductivity,antioxidant capacity and high biological activity which may be the main reason for the biological activity of stabilized biogas slurry.In addition,the results showed that bioactive metabolites,such as gibberellin,ferulic acid,mitogen and and other endogenous stimulants were produced by simultaneous fermentation of biogas slurry.It can be judged that the formation of these substances may be closely related to the biological function of stabilized biogas slurry.In a word,the“multi-stage aerobic biogas slurry stabilization process”can effectively convert the biogas slurry into a liquid fertilizer with stable properties and good biological function.It has wide application value,and can be used not only for agricultural planting,but also with straw for returning to the field.It can also replace microbial agents to promote the optimization of soil indicators and enhance soil fertility.The application of this process is hopeful to develop high efficiency commercial liquid fertilizer,which can be used as a technical means to improve the resource value of biogas slurry.