title: Dewatering and removal of metals from urban anaerobically digested sludge by Fenton's oxidation.
abstract: In this study, the relevance of Fenton's reaction for the treatment of urban anaerobically digested sludge was investigated. In a first part, the impact of the oxidation process on the improvement of the sludge dewaterability was studied. In a second part, the removal of heavy metals from the sludge was examined. Fenton's reaction was carried out with increasing concentrations of Fe2+and H2O2in 1:10 and 1:1 ratios. Dewaterability of the raw sludge was highly improved: the addition of 36 mM Fe2+and 360 mM H2O2led to specific cake resistance (SCR) and capillary suction time (CST) reductions of 99.8% and 98.8%, respectively. Indeed, under these conditions, SCR and CST of respectively 1.04 × 1011m kg-1and 18.5 ± 0.2 s were measured, and the treated sludge could be considered as having 'good dewaterability'. A significant impact was also observed on the removal of heavy metals from the sludge. After 1-h oxidation, Cd, Cr, Cu, Pb and Zn could be removed by 81.1 ± 0.1%, 25.1 ± 0.1%, 87.2 ± 1.1%, 77.3 ± 4.8% and 99.6 ± 0.3%, respectively. These results were consistent with the heavy metals' fractions in the sludge. It could be concluded that the addition of Fe2+and H2O2in a 1:10 ratio was more effective than in a 1:1 ratio. The results were consistent with the extracellular polymeric substance (EPS) contents in raw and treated sludge, since loosely bound EPS decreased significantly after the treatment.
authors.affiliation: a Laboratory of Green Chemistry, School of Engineering Science , Lappeenranta University of Technology , Mikkeli , Finland.
authors.forename: J-M
authors.initials: JM
authors.lastname: Fontmorin
authors.affiliation: a Laboratory of Green Chemistry, School of Engineering Science , Lappeenranta University of Technology , Mikkeli , Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Sillanpää
mesh_terms: D002947:Cities; D005296:Ferrous Compounds / Q000737:chemistry*; D005387:Finland; D006861:Hydrogen Peroxide / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D012722:Sewage / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D005296:Ferrous Compounds; D019216:Metals, Heavy; D016877:Oxidants; D012722:Sewage; D014874:Water Pollutants, Chemical; D014867:Water; C020748:ferrous sulfate; D006861:Hydrogen Peroxide
keywords: Fenton’s reaction; anaerobically digested sludge; extracellular polymeric substances; metal solubilization; sludge dewaterability