title: The thin-layer drying characteristics of sewage sludge by the appropriate foaming pretreatment.
abstract: As dewatered sludge is highly viscous and sticky, the combination of foaming pretreatment and drying process seems to be an alternative method to improve the drying performance of dewatered sludge. In this study, CaO addition followed by mechanical whipping was employed for foaming the dewatered sludge. It was found that the foams were stable and the diameters of bubbles mainly ranged from 0.1 to 0.3 mm. The drying experiments were carried out in a drying oven in the convective mode. The results indicated that foamed sludge at 0.70 g/cm(3) had the best drying performance at each level of temperature, which could save 35-45% drying time to reach 20% moisture content compared with the non-foamed sludge. The drying rate of foamed sludge at 0.70 g/cm(3) was improved with the increasing of drying temperature. The impact of sample thickness on drying rate was not obvious when the sample thickness increased from 2 to 8 mm. Different mathematical models were used for the simulation of foamed sludge drying curves. The Wang and Singh model represented the drying characteristics better than other models with coefficient of determination values over 0.99.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China and Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China E-mail: yzh@hnu.edu.cn.
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Wang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China and Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China E-mail: yzh@hnu.edu.cn.
authors.forename: Zhao-Hui
authors.initials: ZH
authors.lastname: Yang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China and Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China E-mail: yzh@hnu.edu.cn.
authors.forename: Jing
authors.initials: J
authors.lastname: Huang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China and Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China E-mail: yzh@hnu.edu.cn.
authors.forename: Li-Ke
authors.initials: LK
authors.lastname: Wang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China and Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China E-mail: yzh@hnu.edu.cn.
authors.forename: Cheng-Liu
authors.initials: CL
authors.lastname: Gou
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China and Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, China E-mail: yzh@hnu.edu.cn.
authors.forename: Jing-Wu
authors.initials: JW
authors.lastname: Yan
authors.affiliation: The Quality Supervision and Management Station of Civil Air Defense Engineering of Changsha City, Hunan Province, 29 Fuhua Road, Changsha 410013, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
mesh_terms: D003890:Desiccation / Q000379:methods; D008962:Models, Theoretical; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014867:Water / Q000737:chemistry*
chemical_list: D012722:Sewage; D014867:Water