Effect of temperature,pH and organic loading rate on anaerobic acidification pathway of fruit and vegetable waste

The effect of different temperatures(35 ℃,50 ℃)、 pH(4.0,5.0,6.0) and(F/M=2∶1) on the composition of fermentation products was investigated;and acidate type under different parameters.It was shown that high temperature was not conducive to the production of volatile fatty acids(VFAs) and ethanol.The fermentation process was ethanol-type at 50 ℃,while butyrate-type at 35 ℃ under the same pH=6.0.Increasing pH could reduce acidification time,but not improve the total VFAs at 35 ℃.There was relationship between the pH changes and the type of fermentation at 35 ℃.It was ethanol-type fermentation at pH=4.0,the propionic acid-type fermentation at pH=5.0,and the butyric acid-type fermentation at pH=6.0.The optimal conditions for acidification were:F/M=2:1,35 ℃,pH 4.0.The acidification rate could reach 65.1%,of which ethanol concentration was 10 508 mg/L.The percentage of ethanol increased with the OLR increased.When OLR7 gVS/L·d and HRT 5 d,the ethanol-type acidification was obviously observed.