Dry Anaerobic Digestion Performance And Sludge Rheological Behavior Of Mixed FVW And FW

FW?food waste?and FVW?fruits and vegetables waste?are important components of urban domestic waste in China.Anaerobic digestion technology oriented to the harmless treatment and resource utilization is the best solution to deal with these two types of organic waste,while In the anaerobic digestion technology,dry anaerobic digestion has been favored in recent years because of its unique advantages.Therefore,in order to explore the optimal mixing ratio of dry anaerobic digestion of FW?food waste?and FVW?fruits and vegetables waste?,Reveal the operating characteristics of semi-continuous plug flow anaerobic digestion system and the influence of rheological properties on the performance of different semi-continuous dry anaerobic digestion reactors?push flow and complete mixing?.In this study,a batch anaerobic digestion experiments was first carried out to study the response of anaerobic digestion reactor efficiency,process stability and rheological behavior,The optimum mixing ratio and shear rate are clarified.Then,in the self-made plug-flow dry anaerobic digestion reactor based on Dranco process,the semi-continuous anaerobic digestion of FW?food waste?and FVW?fruits and vegetables waste?was carried out under the optimal mixing ratio to further analyze the dry anaerobic digestion reactor.The gas production performance,stability performance,and rheological behavior change with anaerobic digestion.By comparing the performance of batch and semi-continuous plug-flow reactors,the relationship between the two is clearly clarified and the operating characteristics of the semi-continuous plug flow anaerobic digestion system are revealed.And by combining the results of previous experiments,the operational performance of the plug-flow reactor and the high-viscosity fully-mixed anaerobic digestion reactor was compared,and the effect of rheological properties on the running performance of different semi-continuous anaerobic digestion reactors was clarified..Through the above study.Through the above studies,the following results were obtained:?1?The 3:7 dry anaerobic digestion system has better gas production performance,and its methane yield is 0.471 L CH4·gVS^-1_added,which is 12.13%and 18.13%higher than the 2:8 and 4:6 anaerobic digestion systems respectively.?2?For an anaerobic digestion system with a TS content of 20%to 16%,considering the rheological properties and energy consumption,it is appropriate to control the shear rate of the stirring device between10.4S^-1 and 20.9S^-1.?3?The higher TS content?20%?of viscous(apparent viscosity 12766-843mpa.s(?=2.09S^-1-41.8S^-1)sludge produced in a relatively high aspect ratio unstirred reactor Gases are more difficult to discharge from them,and sludge swell phenomenon is more likely to occur.For the design of the plug-flow dry anaerobic digestion reactor operated with reference to the Dranco process,the aspect ratio should be controlled below 3.917 as much as possible.The sludge swell safety altitude shall be not less than 0.3 times the height of the actually planned inoculated sludge?this reserved height does not include the headspace exhaust reserve height?.?4?The push-flow anaerobic digestion reactor has relatively strict push flow properties.In the process of degradation of organic matter,the change of each conventional index with the flow-through position is basically similar to that of the batch anaerobic digestion system with the digestion time.The semi-continuous push-flow anaerobic digestion system can be regarded as a series of batch anaerobic digestion systems with different anaerobic digestion stages.?5?For higher solids sludge mixtures,changes in TS content and water distribution during digestion may be a direct cause of changes in the rheological properties of digested sludge,while other stability indicators such as SCOD,VFA,TAN,pH,PA may be have small impact on the rheological properties of the anaerobic digestion system.?6?Compared to a fully-mixed anaerobic digester system,the plug-flow anaerobic digester system can operate with higher initial solids content.?7?The apparent viscosity has an important influence on the efficiency and stability of the anaerobic digestion system.The higher the apparent viscosity of the sludge mixture,the poorer the mass transfer efficiency of the system,the slower the hydrolysis rate of the organic matter and the consumption rate of the intermediate product TVFA.The worse the apparent viscosity,the higher the TS content,the lower the moisture content,the higher the concentration of the intermediate product,and the worse the homogenization of the digestive system,the more likely to cause local accumulation of intermediate products,resulting in decreased activity of the anaerobic digestion system.