Study On Adsorption Of Biogas Slurry With Pig Manure Anaerobic Digestion By Modified Corn Straw And Its Returning To Field

This study is based on the resource utilization of biogas slurry fermented by corn straw and pig manure.A series of adsorption experiments which corn straw as the carrier and its field returning feasibility test were carried out.In the adsorption test of 20 m L pig biogas slurry with pig manure anaerobic digestion that the adsorption capacity of COD and ammonia nitrogen in biogas slurry as the evaluation index,corn straw greater than 10 mesh was determined as the best adsorption particle size and adsorption material.The modification temperature was60 ℃,the modification time was 4 h,the material liquid ratio was 1:20,the mass fraction of citric acid was 4%,and 0.10 g corn straw was the best dosage.By fitting the isothermal adsorption model,it was determined that the adsorption of COD and NH4+-N in biogas slurry by modified corn straw was monolayer and ion exchange adsorption,and the adsorption reaction was easy to occur.By fitting the kinetic adsorption model,it was proved that the adsorption reaction of modified corn straw for the above two substances in biogas slurry was mainly chemical adsorption.Through thermodynamic analysis,the adsorption of COD and ammonia nitrogen in biogas slurry by modified corn straw met △H < 0,△S< 0 and △G< 0,which proved that the reaction is exothermic,spontaneous and orderly.Through the structural characterization of corn straw by FTIR,XRD and SEM,it was verified that citric acid modification could significantly improve the adsorption performance of corn straw.In the field returning feasibility test,the five heavy metals in the corn straw adsorbed with biogas slurry were detected,and they were all at very low concentrations.Through the germination index test,the germination rate of pakchoi was 97.50% and the germination index was 145%.The pot experiment for 20 days proved that the adsorption modified corn straw could significantly promote the germination rate,germination time,growth height and leaf width of Chinese cabbage.Through the combination of corn straw and biogas slurry,the resource recycling of two kinds of organic wastes is realized.While utilizing the nutrients in biogas slurry,the biogas slurry will be purified,which provides a new idea for the resource utilization of corn straw and biogas slurry,and improves the utilization value of corn straw and biogas slurry to a certain extent.