Study On Stability And Kinetics Of Anaerobic Digestion Of Food Waste Under High Organic Loading

To improve the stability of anaerobic digestion of food waste,main physical and chemical characteristics of food wastes of Chinese representative areas were analyzed in this thesis.Pretreatment of food wastes,co-digestion of food wastes and green waste and product biogas dynamics theory also were study to establish a stable and efficient food waste anaerobic digestion process.The main contents and conclusions are as follows:(1)According to China's “south sweet,north salty,spicy in the East,sour in the west” diet distribution characteristics,collect representative cities of food wastes in winter,summer.Physical-chemical properties of food wastes were analyzed.Total solid content,volatile solid content and salinity of food wastes were significantly differences between regions,but no significant difference in seasons.Regional and seasonal and their interaction significantly influence of eat hutch garbage pH changes.Around food wastes are high nitrogen content of organic waste.Using chemometrics method analyzed anaerobic digestion gas potential of food waste.The theory biogas production of anaerobic digestion of food waste is 900~1100 mL/g VS.(2)Study the influent of acetic acid,ultrasonic wave,heat treatment and cooperative processing method on kitchen waste homogenization effect.The results show that in fixed ultrasonic frequency is 40 KHz,160 W ultrasonic intensity and 50 ? heating preprocessing for 40 minutes is the reasonable process for promoting food waste hydrolysis or dissolution.(3)Study co-digestion of food waste and green waste with high carbon content,the biogas yield and organics removal of anaerobic digestion were monitored.High organic loading of food waste easily lead to batch anaerobic digestion reaction is terminated,and mixed materials on anaerobic digestion have apparent positive synergistic effect.The highest cumulative gas production rate 484.3 mL/g VS,which is food wastes and green wastes separate anaerobic digestion gas weighted average value of 1.99 times.The reasonable organic loading is 15.6 gVS/L*d in semi continuous anaerobic reactor,the average biogas production rate is 7.7 L biogas/L work*d.(4)Mix green waste fiber residue and food wastes to reasonable C/N ratio,efficiency and dynamics mechanism of batch and semi-continuous anaerobic digestion were analyzed.The results showed that food wastes and fiber residue from different green waste have similar law of gas.The largest cumulative biogas yield is 532.1 mL/gVS.Euryarchaeota and Unclassified Archaea are two main methane-producing microorganism in different anaerobic digestion phase.Bidoseresp model is very good for fitting cumulative biogas yield in the batch anaerobic digestion.According to the law of biogas production in the semi continuous anaerobic reactor,the mathematical model of monondpower was established.(5)The efficiency of anaerobic digestion in reactor with polyamide fiber impeller was improved obviously.The cumulative gas production in the first 15 days of batch test was 92.2 % of total gas production,and the removal rate of organics was more than 70%.In organic loading of 18.4 gVS/L * d,stirring parameters were optimized by the uniform square test,and biogas yield of semi continuous anaerobic reactor was 10.8 Lbiogas/Lwork*d.