Anaerobic Digestion Of Food Waste:process Performance And Its Interaction With Microbial Community

In this study,process performence of batch and semi-continuous anaerobic digestion characteristics of food waste were investigated,and explore the influence of pH control on system performance under high load.At the same time,the dynamic change of microbial community and its interaction with system performance during anaerobic digestion were analyzed to provide theoretical basis for improving anaerobic digestion of food waste.Using concentrated pond sludge as the inoculation,the anaerobic system produced 547.8m L/g VS_added of methane at 7.5 g VS/L load.The lag period of the anaerobic system at 15 g VS/L load was longer,and the cumulative methane production was 421.6 m L/g VS_added.When the pH was controlled to 7.5,the methane production increased 30.3%,and the reaction time was shortened by 30 days.Using anaerobic sludge as the inoculation,the anaerobic system performed well at 7.5,15 and 30 g VS/L load,the cumulative methane production exceeded530 m L/g VS_added.The anaerobic system could not be started at 45 g VS/L load.When the pH was controlled to 7.0 and 7.5,the methane production reached 513.2 and 525.3 m L/g VS_added.Using concentrated pond sludge as the inoculation,the abundance of Methanoculleus,Methanobacteria and Methanocellococcus increased obviously at 7.5,15g VS/L load.When the pH was controlled to 7.5 at 15 g VS/L load,the content of Methanosarcina increased,which promoted the improvement of system performance.Using anaerobic sludge as the inoculation,the dominant archaea was Methanospirillum at 7.5,15 g VS/L load,and Methanosarcina was the dominant archaea of reaction medium at 30 g VS/L load.After controlling pH at 45 g VS/L load,Methanosarcina became the dominant genus,which promoted the improvement of system performance.The experimental results of semi-continuous anaerobic digestion show that the system has good performance at low and medium loads.But organic acid inhibition occurred about70 days at high load?OLR:6 g VS/L·day,HRT:20 days?,and the reaction failed.In the stable operation of the system,methanomeles were the dominant archaea,but at high load,the microbial community structure of the anaerobic system changed significantly in the unbalanced stage.The relative abundance of Methanosaeta decreased obviously,but the Methanoculleus increased.The path of degradation of acetic acid to produce methane is blocked,which aggravates the accumulation of propionic acid and n-butyric acid and makes the reaction fail.