Development And Application Of Agricultural Integrated Equipment For Combined Production Of Biogas And Fertilizer And Fertilization Of Residual Digested Liquor

Agricultural solid organic waste with huge output and low utilization rate has been increasingly harmful to soil,water and air environment,which has brought great pressure to rural environmental protection in China.Anaerobic digestion process is an effective means to treat livestock manure and high concentration organic wastewater.However,in the process of anaerobic digestion,not only biogas is produced,but also a large amount of residual biogas slurry,which is difficult to treat.The biogas slurry contains high content of nutrients and amino acids,which can be used as an organic fertilizer.In this paper,a courtyard type gas/fertilizer combined production device was developed,which was suitable for the vast rural areas,and can realize the sustainable utilization of feedstock,gas and fertilizer.Firstly,the integrated gas/fertilizer production device suitable for the courtyard mode was designed and processed for on-site installation and operation.Then using the generated biogas greenhouse temperature experiment to explore the impact of biogas on greenhouse temperature and crop growth,the remaining biogas slurry was used to analyze the main components such as nutrients and heavy metals.Finally,the biogas slurry was used in the field experiment of big cherry to study the effects on the growth and quality of big cherry.The main research contents and results are as follows:(1)The integrated production unit of gas and fertilizer was designed and processed,and the design principle and main technical parameters of the integrated unit were determined.In the actual operation process,under the cold outdoor conditions in winter,the reaction temperature of the system was 40℃,and the dry matter concentration was 10%,the gas production within 18 days was 120.5 m~3,the daily gas production was up to 18 m~3,and the methane concentration was up to 68.7%.(2)The biogas produced by greenhouse heating test,3 groups of burners,in extremely cold weather under the condition of 11 hours of continuous operation,the average temperature of the experimental greenhouse compared with the control group increased by 4.5℃,promote the growth of crops.High-throughput sequencing was performed on the residual biogas slurry and inoculated biogas slurry,and the microbial diversity was compared and analyzed.It was found that the community structure of bacteria,fungi and archaea in the integrated device system had changed greatly,and the system retained the efficient degradation ability of inoculated biogas slurry to cellulose substances.In the system,bacteria,fungi and archaea showed obvious dominant flora,and the function of flora was more concentrated.(3)Conduct quantitative analysis on the main components of residual biogas slurry produced by the integrated gas/fertilizer production equipment according to the existing test methods.It was found that the contents of N,P and K in the biogas slurry were rich,among which the content of ammonia nitrogen as the available nutrient was relatively high.There were many metal elements in the biogas slurry.The analysis of the content of heavy metals in the biogas slurry meets the requirements of the national irrigation water quality standard.The reasonable application of biogas slurry will not cause environmental harm.The high content of amino acids plays an important role in promoting crop growth and improving crop quality.(4)The residual biogas slurry produced by the integrated unit was used in the field experiment of big cherry.It was found that the soil structure of the experimental field was improved by applying biogas fertilizer,the total amount of soil microorganism was increased,and the soil nutrient supply was sufficient to meet the needs of crop growth and development.Compared with the experimental plots applying total flushing and half flushing fertilizer,the chlorophyll content of the crops applying total flushing fertilizer was higher,and the sugar to acid ratio,the content of Vc and the average weight per fruit of large cherry fruit were significantly increased,and the fruit quality was improved.