The Efficiency Of Ultrasonic Pretretatment And Stirring Intensity On Biogas From Straw Fermentation

Crop straw contains abundant biomass energy. It is an important resource for farmers’living and agriculture development. Using straw to produce methane is an important way ofthe comprehensive utilization of the straw, and it is also a recent research hot spot.This paperstudied the efficiency of ultrasonic pretreatment and stirring intensity on straw fermentationby sequencing batch anaerobic fermentation experiments and CSTR anaerobic fermentationexperiments.The experiments of sequencing batch anaerobic fermentation experiments were carriedout by different ultrasonic power and time pretreatment under37℃for50days. Gasproduction rate, cumulative gas， pH value,CH4content in fermentation process wereanalyzed, and the straw microstructure was analyzed by the scanning electron microscopy（SEM） to study the efficiency of ultrasonic pretreatment on straw microstructure and gasproduction rate. Results show that ultrasonic pretreatment can change the microstructure ofstraw, improve gas production rate, accumulative gas production and the CH4content inbiogas, and make the time of achieve maximum daily volume advance.CSTR anaerobic fermentation experiments used the result of sequencing batch anaerobicfermentation experiments that the best ultrasonic pretreatment condition （225w30min） topretreat straw material, the CSTR anaerobic fermentation experiments were carried out under37℃for60days. Gas production rate, cumulative gas, pH value,CH4content, COD, NH₄⁺-Nin fermentation process were analyzed to study the efficiency of ultrasonic pretreatment andstirring intensity on straw fermentation. Results show that ultrasonic pretreatment canimprove gas production rate, accumulative gas production and the content of methane inbiogas, drop the concentration of COD, and increasing stirring intensity can improve gasproduction rate, drop pH value and the concentration of COD.