Batch tests were carried out to analyze the effect of volume ratio, in the range of 10%e50%, on the codigestion
of food waste (FW) and activated sludge (AS). Thermal hydrolysis (TH) pretreatment was
applied to accelerate FW solubilization and enhance the efficiency of anaerobic digestion. The experimental
results showed that the optimal TH temperature for FW solubilizaiton was 150 C in range of 100
e175 C. Simultaneously, in the lab scale anaerobic co-digestion of FW and AS, the soluble proteins,
carbohydrates and short chain fatty acids (SCFAs) concentrations were enhanced with increase of volume
ratio of FW and AS (FW/AS). Biochemical methane potential test showed that FW/AS played an important
role in biogas yield, and the maximal biogas yield of 254.4 mL/gVSS appeared at FW/AS of 30%. The threedimensional
excitation-emission matrix (3D-EEM) fluorescence spectroscopy analysis of digested sludge
indicated that the intensities of tryptophan-like and tyrosine-like substances were highest at FW/AS of
30%, which should be responsible for high biogas yield.