Effects of ultrasonic pretreatment on sludge dewaterability andextracellular polymeric substances distributionin mesophilic anaerobic digestion
Liming Shao , Guanzhao Wang , Huacheng Xu , Guanghui Yu , Pinjing He
DOI:
Received May 25, 2009,Revised October 26, 2009, Accepted , Available online
Volume 22,2010,Pages 474-480
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E ect of ultrasonic pretreatment on sludge dewaterability was determined and the fate of extracellular polymeric substances (EPS)
matrix in mesophilic anaerobic digestion after ultrasonic pretreatment was studied. Characteristics of proteins (PN), polysaccharides
(PS), excitation-emission matrix (EEM) fluorescence spectroscopy and molecular weight (MW) distribution of dissolved organic
matters (DOM) in di erent EPS fractions were evaluated. The results showed that after ultrasonic pretreatment, the normalized capillary
suction time (CST) decreased from 44.4 to 11.1 (sec L)/g total suspended solids (TSS) during anaerobic digestion, indicating that sludge
dewaterability was greatly improved. The normalized CST was significantly correlated with PN concentration (R2 = 0.92, p < 0.01) and
the PN/PS ratio (R2 = 0.84, p < 0.01) in the loosely bound EPS (LB-EPS) fraction. Meanwhile, the average MW of DOM in the LBEPS
and tightly bound EPS (TB-EPS) fractions also had a good correlation with the normalized CST (R2 > 0.66, p < 0.01). According
to EEM fluorescence spectroscopy, tryptophan-like substances intensities in the slime, LB-EPS and TB-EPS fractions were correlated
with the normalized CST. The organic matters in the EPS matrix played an important role in influencing sludge dewaterability.
