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Evaluation of Dewatering Performance and Fractal Characteristics of Alum Sludge.

Sun Y, Fan W, Zheng H, Zhang Y, Li F, Chen W - PLoS ONE (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.


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Effect of pH on fractal dimension.
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pone.0130683.g008: Effect of pH on fractal dimension.

Mentions: The effect of dosage on fractal dimension and floc size is shown in Figs 6 and 7. As shown in Fig 6, the fractal dimension of sludge flocs increased with increased dosage. The fractal dimension of CPAM2 was greater than that of CPAM1 and CPAM3. Fig 7 and S1 Fig shows the effect of dosage on the floc size, which increased with increased dosage, and can be arranged in the following order: CPAM2 > CPAM3 > CPAM1. The evidence from Fig 7 and S1 Fig demonstrates that high floc size is associated with high flocculant dose. The trend of fractal dimension shown in Fig 6 is generally consistent with the trend of floc size shown in Fig 7 The effect of pH on fractal dimension is shown in Fig 8 The fractal dimension rapidly increased initially with increased pH and then slowly decreased. The fractal dimensions of sludge flocculated with different CPAM at different pH values were in the following order: CPAM2 > CPAM3 > CPAM1. At pH 7, the maximum fractal dimensions of CPAM1, CPAM2, and CPAM3 were 1.45, 1.53, and 1.49, respectively.


Evaluation of Dewatering Performance and Fractal Characteristics of Alum Sludge.

Sun Y, Fan W, Zheng H, Zhang Y, Li F, Chen W - PLoS ONE (2015)

Effect of pH on fractal dimension.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4487249&req=5

pone.0130683.g008: Effect of pH on fractal dimension.
Mentions: The effect of dosage on fractal dimension and floc size is shown in Figs 6 and 7. As shown in Fig 6, the fractal dimension of sludge flocs increased with increased dosage. The fractal dimension of CPAM2 was greater than that of CPAM1 and CPAM3. Fig 7 and S1 Fig shows the effect of dosage on the floc size, which increased with increased dosage, and can be arranged in the following order: CPAM2 > CPAM3 > CPAM1. The evidence from Fig 7 and S1 Fig demonstrates that high floc size is associated with high flocculant dose. The trend of fractal dimension shown in Fig 6 is generally consistent with the trend of floc size shown in Fig 7 The effect of pH on fractal dimension is shown in Fig 8 The fractal dimension rapidly increased initially with increased pH and then slowly decreased. The fractal dimensions of sludge flocculated with different CPAM at different pH values were in the following order: CPAM2 > CPAM3 > CPAM1. At pH 7, the maximum fractal dimensions of CPAM1, CPAM2, and CPAM3 were 1.45, 1.53, and 1.49, respectively.

Bottom Line: 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.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.


Related in: MedlinePlus