title: Effect of ultrasonic pretreatment on anaerobic digestion and its sludge dewaterability.
abstract: To investigate the effect of ultrasonic pretreatment on anaerobic digestion and sludge dewaterability and further to probe into the influencing factors on sludge dewaterability, sludge flocs were stratified into four fractions: (1) slime; (2) loosely bound extracellular polymeric substances (LB-EPS); (3) tightly bound EPS (TB-EPS); and (4) EPS-free pellets. The results showed that ultrasonic pretreatment increased the anaerobic digestion efficiency by 7%-8%. Anaerobic digestion without ultrasonic pretreatment deteriorated the sludge dewaterability, with the capillary suction time (CST) increased from 1.42 to 47.3 (sec x L)/g-TSS. The application of ultrasonic pretreatment firstly deteriorated the sludge dewaterability (normalized CST increased to 44.4 (sec x L)/g-TSS), while subsequent anaerobic digestion offset this effect and ultimately decreased the normalized CST to 23.2 (sec x L)/g-TSS. The dewaterability of unsonicated sludge correlated with protein (p = 0.003) and polysaccharide (p = 0.004) concentrations in the slime fraction, while that of sonicated sludge correlated with protein concentrations in the slime and LB-EPS fractions (p < 0.05). Fluorescent excitation-emission matrix analysis showed that the fluorescence matters in the LB-EPS fraction significantly correlated with sludge dewaterability during anarobic digestion.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. chenghuaxu@163.com
authors.forename: Huacheng
authors.initials: H
authors.lastname: Xu
authors.forename: Pinjing
authors.initials: P
authors.lastname: He
authors.forename: Guanghui
authors.initials: G
authors.lastname: Yu
authors.forename: Liming
authors.initials: L
authors.lastname: Shao
mesh_terms: D000693:Anaerobiosis; D009930:Organic Chemicals / Q000032:analysis; D010316:Particle Size; D012722:Sewage / Q000737:chemistry*; D013010:Sonication / Q000379:methods*; D018505:Waste Management / Q000379:methods*; D014867:Water
chemical_list: D009930:Organic Chemicals; D012722:Sewage; D014867:Water