title: Enhanced dewaterability of waste-activated sludge by combined cationic polyacrylamide and magnetic field pretreatment.
abstract: The potential function of combining magnetic field (MF) pretreatment with cationic polyacrylamide (CPAM) additive on enhancing the dewaterability of waste-activated sludge was investigated in the present work. Two reactors were involved in a specially designed experimental apparatus, one of which was built with MF accessories. Several parameters were conducted, including CPAM dosages, MF strengths and processing times, respectively. Capillary suction time (CST) and specific resistance to filtration (SRF) were used to evaluate sludge dewaterability. Extracellular polymeric substances (EPS) concentration was also determined in an attempt to identify the observed changes in dewaterability. It was indicated by the results that both CPAM conditioning and MF pretreatment on sludge can lower CST and SRF values. However, subjecting to a combination of MF pretreatment and CPAM conditioning, sludge dewaterability was significantly enhanced beyond the level observed of CPAM addition alone. The lowest CST and SRF values of 36.5 s and 0.75×10(12) m kg(-1), respectively, were obtained when sludge was co-conditioned by CPAM (at a dosage of 40 mg L(-1)) and MF (at an induction of 40 mT) for 30 min, suggesting the optimal condition for enhancing sludge dewaterability. It is also shown from the significant correlations between EPS, protein, polysaccharide and CST/SRF that the increment of EPS concentration in sludge supernatant may be the major reason for the enhancement of dewaterability.
authors.affiliation: a Environmental Research Institute of Shanghai Institute of Technology , Shanghai 200235 , People's Republic of China.
authors.forename: Dongsu
authors.initials: D
authors.lastname: Bi
authors.forename: Xiaopin
authors.initials: X
authors.lastname: Guo
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Cai
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yu
authors.forename: Dingmei
authors.initials: D
authors.lastname: Wang
authors.forename: Yueqiang
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry* / Q000528:radiation effects; D002412:Cations; D007220:Industrial Waste / Q000517:prevention & control*; D060526:Magnetic Fields; D011829:Radiation Dosage; D012037:Refuse Disposal / Q000379:methods*; D012722:Sewage / Q000032:analysis / Q000737:chemistry*; D014867:Water / Q000032:analysis* / Q000737:chemistry*; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D002412:Cations; D007220:Industrial Waste; D012722:Sewage; D014867:Water; D000099166:Polyacrylamides
keywords: cationic polyacrylamide; co-conditioning; extracellular polymeric substances; magnetic field; sludge dewaterability