title: Impact of ultrasonic treatment on dewaterability of sludge during Fenton oxidation.
abstract: Fenton oxidation was compared with Fenton oxidation coupled with ultrasonication (Fenton + US) for sludge dewatering. Different Fenton reagent (H2O2, Fe(2+)) concentrations, pH, and reaction times were studied in different systems on the basis of the specific resistance to filtration (SRF) and capillary suction time (CST). It was found that Fenton + US can significantly reduce Fe(2+) and H2O2 dosages and reaction times. After ultrasonication of the system at pH 3, with an ultrasonic frequency of 25 kHz and a sound energy density of 100 W/L, the Fe(2+), H2O2 dosage, and reaction time were reduced by 66.7, 75.0, and 75.0 %, respectively, when compared with Fenton oxidation at the same dewaterability of sludge. The microstructure of sludge and hydroxyl radical (·OH) density in Fenton oxidation and Fenton + US was further examined. Fenton + US produced more · OH in a sludge system than did individual Fenton oxidation. The concentration of · OH in Fenton + US fell from 79.2 to 6 mg/L over 3.5 h, while the concentration of · OH in Fenton oxidation fell from 59.6 to 1 mg/L over 2 h, thus destroying the microstructure of sludge more effectively. Sludge treated using Fenton + US for 30 min showed a much thinner and looser microstructure.
authors.affiliation: School of Environment, Tsinghua University, 100084, Beijing, China, jianguoj@mail.tsinghua.edu.cn.
authors.forename: Jianguo
authors.initials: J
authors.lastname: Jiang
authors.forename: Changxiu
authors.initials: C
authors.lastname: Gong
authors.forename: Sicong
authors.initials: S
authors.lastname: Tian
authors.forename: Shihui
authors.initials: S
authors.lastname: Yang
authors.forename: Yujing
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D005374:Filtration; D006861:Hydrogen Peroxide; D007501:Iron; D010084:Oxidation-Reduction; D012722:Sewage / Q000032:analysis / Q000737:chemistry*; D014465:Ultrasonics; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: C045076:Fenton's reagent; D012722:Sewage; D006861:Hydrogen Peroxide; D007501:Iron
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