title: Evaluation of Dewatering Performance and Fractal Characteristics of Alum Sludge.
abstract: The dewatering performance and fractal characteristics of alum sludge from a drinking-water treatment plant were investigated in this study. Variations in residual turbidity of supernatant, dry solid content (DS), specific resistance to filtration (SRF), floc size, fractal dimension, and zeta potential were analyzed. Sludge dewatering efficiency was evaluated by measuring both DS and SRF. Results showed that the optimum sludge dewatering efficiency was achieved at 16 mg∙L(-1) flocculant dosage and pH 7. Under these conditions, the maximum DS was 54.6%, and the minimum SRF was 0.61 × 10(10) m∙kg(-1). Floc-size measurements demonstrated that high flocculant dosage significantly improved floc size. Correlation analysis further revealed a strong correlation between fractal dimension and floc size after flocculation. A strong correlation also existed between floc size and zeta potential, and flocculants with a higher cationic degree had a larger correlation coefficient between floc size and zeta potential. In the flocculation process, the main flocculation mechanisms involved adsorption bridging under an acidic condition, and a combination between charge neutralization and adsorption-bridging interaction under neutral and alkaline conditions.
authors.affiliation: Key laboratory of the Three Gorges Reservoir Region's Eco-Environment, State Ministry of Education, Chongqing University, Chongqing, China; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing, China.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Key laboratory of the Three Gorges Reservoir Region's Eco-Environment, State Ministry of Education, Chongqing University, Chongqing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Fan
authors.affiliation: Key laboratory of the Three Gorges Reservoir Region's Eco-Environment, State Ministry of Education, Chongqing University, Chongqing, China; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing, China.
authors.forename: Huaili
authors.initials: H
authors.lastname: Zheng
authors.affiliation: National Key Laboratory of Fundamental Science of Micro/Nano-Devices and System Technology, College of Materials Science and Engineering, Chongqing University, Chongqing, China.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Yangtze River Water Environment, Ministry of Education, State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, China.
authors.forename: Fengting
authors.initials: F
authors.lastname: Li
authors.affiliation: Key laboratory of the Three Gorges Reservoir Region's Eco-Environment, State Ministry of Education, Chongqing University, Chongqing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
mesh_terms: D000534:Alum Compounds / Q000737:chemistry*; D005374:Filtration; D005427:Flocculation; D017709:Fractals; D006863:Hydrogen-Ion Concentration; D009391:Nephelometry and Turbidimetry; D012722:Sewage / Q000737:chemistry*; D055672:Static Electricity; D014867:Water / Q000737:chemistry*; D018508:Water Purification
chemical_list: D000534:Alum Compounds; D012722:Sewage; D014867:Water; C041524:aluminum sulfate