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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 dosage on SRF.
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pone.0130683.g005: Effect of dosage on SRF.

Mentions: The SRF of sludge was used to evaluate the degree of difficulty of sludge dewatering. The effect of cationic flocculant dosage on sludge specific resistance is shown in Fig 5 With increased dosage, the SRF of the sludge decreased initially, and then increased straight after 12 mg∙L-1 dosage. The minimum SRF of CPAM1, CPAM2, and CPAM3 were 0.82 × 1010, 0.61 × 1010, and 0.71 × 1010 m∙kg-1, respectively, obtained at 12 mg∙L-1 dosage. The original sludge SRF was 19.8 × 1010 m∙kg-1 without the addition of flocculant. The comparison shows that the SRF could be reduced and improve the dewatering performance significantly by addition of flocculant, making the sludge SRF decrease more than the observed magnitude. When the dosage was less than 20 mg∙L-1, the SRF of each flocculant was in the following order: CPAM1 > CPAM3 > CPAM2. As shown in Fig 5, CPAM2 with higher intrinsic viscosity had better flocculation performance and lower SRF compared with CPAM1. Meanwhile, between CPAM2 and CPAM3, the flocculant with higher cationic degree had lower SRF. Thus, the comparison indicated that high intrinsic viscosity or high cationic degree results in the reduction of the SRF and improvement of the sludge dewatering performance.


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 dosage on SRF.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0130683.g005: Effect of dosage on SRF.
Mentions: The SRF of sludge was used to evaluate the degree of difficulty of sludge dewatering. The effect of cationic flocculant dosage on sludge specific resistance is shown in Fig 5 With increased dosage, the SRF of the sludge decreased initially, and then increased straight after 12 mg∙L-1 dosage. The minimum SRF of CPAM1, CPAM2, and CPAM3 were 0.82 × 1010, 0.61 × 1010, and 0.71 × 1010 m∙kg-1, respectively, obtained at 12 mg∙L-1 dosage. The original sludge SRF was 19.8 × 1010 m∙kg-1 without the addition of flocculant. The comparison shows that the SRF could be reduced and improve the dewatering performance significantly by addition of flocculant, making the sludge SRF decrease more than the observed magnitude. When the dosage was less than 20 mg∙L-1, the SRF of each flocculant was in the following order: CPAM1 > CPAM3 > CPAM2. As shown in Fig 5, CPAM2 with higher intrinsic viscosity had better flocculation performance and lower SRF compared with CPAM1. Meanwhile, between CPAM2 and CPAM3, the flocculant with higher cationic degree had lower SRF. Thus, the comparison indicated that high intrinsic viscosity or high cationic degree results in the reduction of the SRF and improvement of the sludge dewatering performance.

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