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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: 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).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.

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.


Effect of pH on DS.
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pone.0130683.g004: Effect of pH on DS.

Mentions: The effect of pH on DS is shown in Fig 4, With increased pH, the DS values initially increased quickly, and then decreased rapidly. At pH 7, the maximum DS of CPAM1, CPAM2, and CPAM3 were 37.2%, 54.6%, and 50.3%, respectively. Sludge dewatering performances were much poorer under strong alkaline or acidic sludge than under neutral (weak acid/alkaline) condition. Therefore, neutral condition was suitable for sludge dewatering.


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 DS.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0130683.g004: Effect of pH on DS.
Mentions: The effect of pH on DS is shown in Fig 4, With increased pH, the DS values initially increased quickly, and then decreased rapidly. At pH 7, the maximum DS of CPAM1, CPAM2, and CPAM3 were 37.2%, 54.6%, and 50.3%, respectively. Sludge dewatering performances were much poorer under strong alkaline or acidic sludge than under neutral (weak acid/alkaline) condition. Therefore, neutral condition was suitable for sludge dewatering.

Bottom Line: 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).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.

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.