摘要
Four batch experiments of hydrolysis and acidification were carried out to investigate the distributions of proteins(PN)and polysaccharides(PS)in the sludge,the PN/PS ratio,the particle sizes,and their relationship with sludge dewaterability(as determined by capillary suction time,CST).The sludge flocs were stratified through centrifugation-and ultrasound-based method into four fractions:(1)slime,(2)loosely bound extracellular polymeric substances(LB-EPS),(3)tightly bound EPS(TB-EPS),and(4)pellet.The results showed that PN was mainly partitioned in the pellet(80.7%)and TB-EPS(9.6%)fractions,while PS distributed evenly in the four fractions.During hydrolysis and acidification,PN was transferred from the pellet and TB-EPS fractions to the slime fraction,but PS had no significant transfer trends.The mean particle sizes of the sludge flocs decreased with hydrolysis and acidification.The pH had a more significant influence on the dewaterability of sludge flocs than temperature.Sludge dewaterability during hydrolysis and acidification processes greatly deteriorated from 9.7 s at raw sludge to 340-450 s under alkaline conditions.However,it was just slightly increased under acidic conditions.Further investigation suggested that CST was affected by soluble PN,soluble PN/PS,and particle sizes of sludge flocs,but was affected slightly by total PN,PS,or PN/PS in the whole sludge flocs and other fractions(except slime).
基金
supported by the National Hi-Tech Research and Development Program(863)of China(No.2006AA06Z384).
