Improved bioconversion of volatile fatty acids from waste activated sludge by pretreatment.
Batch tests were conducted to analyze the influence of various pretreatment methods including thermo-alkaline, thermo-acid, ultrasonic-alkaline, and ultrasonic-acid on the bioconversion of volatile fatty acids (VFAs) from waste activated sludge. Experimental results showed that total VFAs (TVFAs) increased by 68.2% for ultrasonic-alkaline and 59.1% for thermo-alkaline. The TVFAs bioconversion in the case of the thermo-acid or ultrasonic-acid pretreatment, however, was lower than that without pretreatment. The results of VFA distribution showed that acetic acid was the most prevalent product, with a fraction of 35.5 to 57.2% for all cases. The mechanism of VFA production was then investigated. Results revealed that, in the two alkaline-pretreated slurries, soluble COD and soluble BOD/soluble COD significantly increased to yield more soluble substrate for the subsequent fermentation. Soluble proteins comprised the main substance provided that was converted to VFAs. A further investigation indicated that volatile (organic) solids, including insoluble proteins, in the solid phase of the samples pretreated with these two methods were hardly consumed during the fermentation.
Liu
X L
XL
Laboratory of Environmental Biotechnology, School of Biotechnology, Jiangnan University, Wuxi, China.
Liu
H
H
Du
G C
GC
Chen
J
J
D001673:Biodegradation, Environmental; D002241:Carbohydrates; D005232:Fatty Acids, Volatile / Q000737:chemistry* / Q000378:metabolism; D005285:Fermentation; D006868:Hydrolysis; D011506:Proteins; D012722:Sewage / Q000737:chemistry*; D012995:Solubility
D002241:Carbohydrates; D005232:Fatty Acids, Volatile; D011506:Proteins; D012722:Sewage