| With the high-quality development of the economy,the amount of urban domestic waste is also increasing day by day.Among them,kitchen waste,as an important part of domestic waste,has been paid more and more attention to its treatment methods.Due to its high organic content,high water content and easy degradation,kitchen waste is a good substrate for anaerobic digestion treatment.The method of anaerobic digestion treatment of kitchen waste helps to improve the level of resource utilization of kitchen waste and reduce environmental pollution.This way of using kitchen waste to produce clean energy such as hydrogen and methane has also become a research direction for many scholars.This article mainly studies the first stage of anaerobic digestion(anaerobic hydrolysis stage).Through numerical simulation and experimental verification methods,the blades and reactor cylinder of a mechanical stirred tank bioreactor(CSTR)are designed and optimized,and suitable bioreactor operating parameters for the anaerobic hydrolysis stage are found through single-factor experiments and response surface experiments analysis.At the same time,the experimental data is fitted to different mathematical models of bioreaction kinetics using the optimal operating parameters,and suitable kinetic mathematical models are found to describe and predict the bioreaction in the reactor.To achieve the above goals,this article uses COMSOL software to numerically simulate the reactor model,and conducts theoretical analysis by coupling the turbulent field with the p Hysical field of rare substances.By comparing the velocity distribution,shear rate distribution and mixing degree generated by different impeller types,the impeller with the highest mixing efficiency is selected for stirring the bioreactor.By comparing different radius ratios and height-to-diameter ratios,the reactor cylinder with the highest mixing efficiency is selected for use in the bioreactor.By analyzing the results of single-factor experiments and response surface experiments,the effects and significance of reaction temperature,environmental p H,motor speed and stop ratio on hydrolysis efficiency and the interaction between various parameters were explored.The reaction conditions that are most suitable for anaerobic hydrolysis of kitchen waste were selected as the optimal operating parameters for the reactor.Finally,the experimental data were non-linearly fitted using the Logistic model,Dose Resp model and SGompertz model to select the reaction kinetic mathematical model that best describes the reaction process.This article mainly had studied the results and conclusions:(1)The accuracy of the CFD model set had been verified by experiments.(2)By coupling the turbulent field with the p Hysical field of rare substances,it had been concluded that the 45°folded turbine installed under suction at the bottom had had a better mixing effect in the bioreactor.(3)When the radius ratio of the reactor cylinder had been 1:0.6 and the height-diameter ratio had been 5:3,the mixing effect of CSTR had been best.(4)Through response surface experiments,it had been found that the highest efficiency of anaerobic hydrolysis of kitchen waste had been achieved when the reaction temperature had been 36.24 ℃,environmental p H had been 5.68,motor speed had been 104.78r/min,and stop ratio had been set to 11min:60min.(5)Through non-linear fitting of experimental data,it had been found that the Logistic model could well describe and predict the law of reaction process,and the correlation coefficient R2 had reached0.9982.This article clearly defines the influence of structural parameters and operating parameters of bioreactors on anaerobic hydrolysis of kitchen waste,systematically studies the influence of different impellers and impeller angles on the flow field in the reactor,discusses the fitting effect of different reaction kinetics models on anaerobic hydrolysis of kitchen waste,and provides reference for the design optimization of bioreactors for anaerobic hydrolysis of kitchen waste. |
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