Optimization Acidification Treatment Of Cattle Manure And Research On Parameters Of Anaerobic Fermentation With Completly Mixed Fixed-bed

In order to improve the production of methane of anaerobic fermentation of the cow dung, the effect ofacidizing time, stirring frequency, materials density and nitrogen content of acidizing of cow dung on theproduction of methane was studied by the two phase anaerobic fermentation technology. Base on single factorexperiment, using acidizing time, materials density and nitrogen content as independent variable, andproduction of methane as response values, the regression model of the effect of acidulation on production ofmethane was built by response surface analysis of three factors and five levels, then the significant differenceand interaction were analyzed. This method could be used on experimental analysis according to theverification test, and the production of methane and removal rate of COD could be improved under theoptimization condition. The microbial diversity was investigated using the methods of plating and16S rDNAclone technology. Using the completly mixed fixed-bed as the reactor of anaerobic fermentation, cow dungthrough acidulation as raw material, and By the production of methane t as index,carrier material of fixed-bedwas screened,and the operating parameter of fixed bed reactor was optimized. The main results were asfollows:According to the result of single factor of acidulation, the optimum acidizing time, stirring frequency,materials density and nitrogen content was96h,3times/24h,8.0%and1.28g/L respectively. Under thecondition of acidulation that35℃of temperature,3times/24h of stirring frequency, acidificationconcentration had the greatest impact on the production of methane,the following was addition of nitrogen, andthe minima was acidification time, through the analysis by response surface analysis of three factors and fivelevels. The optimum conditions of acidulation were93.7h of acidizing time,8.3%of materials density,0.58g/L of nitrogen content,under this condintion, the methane production, biogas production, removal rate of VSand COD were increased by14.3%、44.6%、41.7%and33.9%respectively, however there was non-significantimpact on the change of content of cellulose, hemicellulose and lignose under acidulation.The microbial diversity of cow dung-liquor of control and acidulation was analyzed by16S rDNA clonetechnology. The acid-forming bacteria of control was composed with Bacteroidetes, Enterobacter, Pantoeadispersa and Uncultured bacterium. The acid-forming bacteria of acidulation had a high microbial diversity.The acid-forming bacteria of acidulation was composed with Uncultured rumen bacterium, which coulddecompose saccharides into VFA,and involved in body metabolism by gastric absorption, and Unculturedbacterium.49,which could improve the content of VFA in activated sludge.Using the completly mixed fixed-bed as the reactor of anaerobic fermentation, cow dung throughacidulation as raw material, The influence of carbon fiber, bamboo carbon fiber and plastic as fixed-bed carrieron the production of methane were researched. The optimal material was carbon fiber. Compared with thecontrol group,the biogas production, methane production and removal rate of COD were increased by12.1%、15.6%and17.5%respectively.Using the carbon fiber as fixed-bed carrier, and cow dung through acidulation, the anaerobic fermentationwas carried out.Through the single factor experiment of stirring frequency, materials density, runningtemperature and hydraulic retention time of static bed, the optimum stirring frequency, materials density,operating temperature and HRT were24h,8%,35℃and12d respectively,which were analyzed base on the influence of significance on the methane production and removal rate of COD.The results of the above research indicated that after acidulation,the microbial diversity of acid-formingbacteria was improved, which leaded to generation of organic acid produced through metabolism with differenttypes of saccharide,and the content of VFA utilized by methane bacteria was also improved,and it wasconducive to the generation of methane, thereby could increase the content of methane, and the removal rate ofCOD had also been improved.