Study On The Succession Of Safe Resource Utilization Mode Of Biogas Slurry Under The Environment Response

The large-scale farm and its surrounding agricultural(forest)land form a planting and breeding complex ecosystem,in which the breeding animals are the main body and the surrounding agricultural and forestry space is the environment.Feed is produced from the environment for animal breeding and production,and the manure and urine waste produced by the animals return to the environment in the form of biogas slurry and biogas residue to produce feed crops,forming a closed cycle of energy.However,the biogas slurry returning to agricultural and forestry land often encounters the technical bottleneck of environmental pollution,which causes a huge obstacle to the energy and material circulation in the system.In this paper,the environmental capacity limit value of biogas fluid consumption in Camellia oleifera forest was studied and the environmental risk of groundwater was evaluated.Secondly,based on the objective reality of the environmental risk of biogas fluid consumption in forest land,the research idea of"biogas fluid purification first and then return to the environment" was replaced by the research idea of"biogas fluid purification first and then return to the environment",and the purification technology with high efficiency and low consumption of biogas fluid removal of high COD and ammonia nitrogen was successfully studied.The new mode of biogas fluid safety and resource utilization was innovated.The results are as follows:(1)When biogas slurry is directly applied to Camellia oleifera forest land,the antibiotic will pollute the soil environment and groundwater environment;without considering the antibiotic factor,1 m3/(mu·month)of biogas slurry is the safe dosage,and if it exceeds 2 m3/(mu·month),the groundwater quality of Camellia oleifera forest land will deteriorate rapidly.(2)Based on the reality of environmental quality risk of biogas slurry returning to forest(Agriculture)directly,this study innovated the purification technology of biogas slurry.The main content includes CaO-AlCl3 co-precipitation agent precipitation method to remove the colloidal and granular organic matter of biogas slurry,and then the remaining clear liquid is introduced into the electrodialysis device to separate the ammonia nitrogen by electrodialysis method,at the same time to eliminate the true soluble organic matter and produce purified water.The process parameters were optimized including:the ratio of CaO-AlCl3 co-precipitating agent 1:2.5,the volume ratio of co-precipitating agent 1:1,pH=9;the limiting current density of ammonia nitrogen removal by electrodialysis,the real soluble organic matter 1.60 mA/cm2,pH=8.5,the hydraulic retention time 15 min,the working voltage 20V.Under the condition of optimized parameters,the organic matter in granular and colloidal state can be completely removed by co-precipitation treatment,the organic matter in real solution can be completely removed by electrodialysis and 94%ammonia nitrogen can be removed.(3)The mechanism of removing organic matter in colloidal state by co-precipitation and the mechanism of removing ammonia nitrogen and real soluble organic matter by electrodialysis were clarified.(4)The environmental indicators of the purified water produced by the innovative purification process of biogas slurry are far lower than the national emission standard of livestock and poultry breeding pollutants(GB18596-2001).(5)The innovative model of biogas slurry returning to the environment of agriculture and forestry is studied.The biogas slurry is co precipitated to get purified water,and then the organic matter precipitation and ammonium salt concentrated water are separated.The purified water can be used again to wash pig houses,the organic matter precipitation returns to the soil with soil improver,and the ammonium salt concentrated water is applied to crops as fertilizer.Based on the above results,this study achieved the goal of no pollution return of biogas slurry to the environment,and solved the technical bottleneck of pollution of biogas slurry to the environment of agriculture and forestry.It can be predicted that the popularization and application of this technology mode will provide efficient technology and theoretical basis for the normal operation of intensive planting and breeding complex ecosystem.