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 ...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) .展开更多
Effect of sludge retention time( SRT) on the removal of potential and polysaccharides in an anaerobic / anoxic / aerobic( AAO) process was investigated. The Lowry method and anthrone method were used to detect protein...Effect of sludge retention time( SRT) on the removal of potential and polysaccharides in an anaerobic / anoxic / aerobic( AAO) process was investigated. The Lowry method and anthrone method were used to detect proteins and polysaccharides. Total removal efficiency of proteins at SRT of 10 to 25 d in the AAO system was higher than 90%. Polysaccharides removal efficiencies were above 80% when SRT was increased from 15 to 25 d,whereas only 81% of polysaccharides was removed at SRT of 10 d. The biodegradation part of proteins and polysaccharides increased from87. 40% to 93% and from 74. 22% to 86. 94% with increasing SRTs.The ratios of polysaccharides and proteins in extracellular polymer substances( EPSs) were around 1. 5-3 in different SRTs. As SRT increasing,polysaccharides and proteins discharged with residual sludge decreased gradually. The amount of EPSs decreased with increasing SRTs.展开更多
基金supported by the National Hi-Tech Research and Development Program (863) of China (No. 2006AA06Z384).
文摘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National Natural Science Foundations of China(Nos.21477018,21007010)Hunan Province Ministry of Transportation Scientific Research Projects,China(Nos.200908,201105)Ministry of Transport Science and Technology Program,China(No.2010353343290)
文摘Effect of sludge retention time( SRT) on the removal of potential and polysaccharides in an anaerobic / anoxic / aerobic( AAO) process was investigated. The Lowry method and anthrone method were used to detect proteins and polysaccharides. Total removal efficiency of proteins at SRT of 10 to 25 d in the AAO system was higher than 90%. Polysaccharides removal efficiencies were above 80% when SRT was increased from 15 to 25 d,whereas only 81% of polysaccharides was removed at SRT of 10 d. The biodegradation part of proteins and polysaccharides increased from87. 40% to 93% and from 74. 22% to 86. 94% with increasing SRTs.The ratios of polysaccharides and proteins in extracellular polymer substances( EPSs) were around 1. 5-3 in different SRTs. As SRT increasing,polysaccharides and proteins discharged with residual sludge decreased gradually. The amount of EPSs decreased with increasing SRTs.
