Effect Of Different Additives On Methane Produced By Mixed Anaerobic Fermentation Of Rice Straw

In order to improve the utilization efficiency of rice straw and pig manure,improve the anaerobic fermentation gas production efficiency of rice straw and pig manure,increase methane production,and optimize and improve the field mixed anaerobic fermentation methane production technology of rice straw,rice straw and pig manure were selected as the fementation raw materials,paddy field soil was selected as an inoculum in this study,and the laboratory experiments and the rice field experiments were conducted respectively.In the laboratory experiment,different types and different amounts of additives（Tween 20,Humic acid,NaHCO₃,and Phosphate rock）were added.In the rice field experiment by adding Tween 20 and Humic acid and their different concentrations.To study the cumulative gas production,methane content,pH value and volatile fatty acids,straw lignocellulose degradation and soil organic matter,total nitrogen and total phosphorus content,as well as the changes in the structure and diversity of archaeal communities at different periods,reveal the types of additives and the effect and mechanism of the added amount on the methanogenesis of mixed anaerobic fermentation of rice straw and pig manure.The main research conclusions are as follows:（1）The addition of additives has no significant effect on the change pattern of gas production,but only improves the overall level and peak value of gas production.（2）The addition of additives has a significant promotion effect on gas production and gas concentration,and its overall effect,the laboratory experiments is NaHCO₃> Tween 20> Humic acid> Control> Phosphate ore powder,the cumulative gas production with NaHCO3 treatment The highest average gas concentration was the highest with Tween 20;the rice field experiments was Humic Acid> Tween 20> Control.（3）The addition of additives is conducive to the degradation of rice straw cellulose and hemicellulose in mixed anaerobic fermentation,and has no significant effect on lignin degradation;the addition of phosphate rock inhibits the degradation of rice straw lignocellulose and Inhibit the increase of soil organic matter,total nitrogen and total phosphorus.（4）The addition of Tween 20,Humic acid and NaHCO₃ is conducive to improving soil fertility.The addition of 0.20 g/L Tween 20,0.125 g/L Humic acid and 0.84 g/L NaHCO₃ in laboratory experiments can significantly improve soil organic matter,for nitrogen and total phosphorus.The rice field experiments had the best treatment levels of 0.15 g/L Humic acid and 0.30 g/L Tween 20.（5）The addition of additives has a significant impact on the abundance and diversity of archaeal bacteria.Compared with the abundance and diversity of archaeal bacteria in the middle and late fermentation,Tween 20,Humic acid and NaHCO₃ showed a decreasing trend.The control showed an increasing trend.The addition of additives has no significant effect on the structure of the archaeal community.In the middle and later stages of fermentation,Methanosarcina,Methanococcus,Methanocystis,Methanoma,Methanobacterium,Methanobacillus and Methanospirillum is the dominant flora,and the additives only affect the relative abundance of the dominant flora.The above results indicate that proper Tween 20,Humic acid and NaHCO₃ incorporation can promote the gas production rate of in the laboratory anaerobic fermentation,rice straw decomposition rate and soil fertility.The addition of additives obviously affected the abundance and diversity of archaeal bacteria,and had no significant effect on the formation of archaeal communities.In rice field experiments,it was verified that Tween 20 and Humic acid have the same mechanism of action on anaerobic fermentation as the general trend laboratorys.In order to improve the efficiency of anaerobic fermentation,Tween 20,Humic acid and NaHCO₃ can be used as references when performing anaerobic fermentation laboratorys or rice fields.