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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.


Related in: MedlinePlus

Effect of pH on zeta potential.
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pone.0130683.g011: Effect of pH on zeta potential.

Mentions: The effect of pH on the zeta potential is shown in Fig 11 With increased pH, zeta potential declined rapidly after the initial slow increase. When pH reached 7, the maximum zeta potentials of CPAM1, CPAM2, and CPAM3 were 20.4, 30.0, and 28.0 mV, respectively. Under acidic conditions, the high concentration of H+ in the sludge system made it positively charged and changed PAC into Al3+. The polymer chains are attached to the surface of particle at several points by adsorption to unattached segments that extend into the bulk of the liquid; the chain may loop back and attach to the same particle and other particles, eventually linking particles together to form flocs [47–48].


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 zeta potential.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0130683.g011: Effect of pH on zeta potential.
Mentions: The effect of pH on the zeta potential is shown in Fig 11 With increased pH, zeta potential declined rapidly after the initial slow increase. When pH reached 7, the maximum zeta potentials of CPAM1, CPAM2, and CPAM3 were 20.4, 30.0, and 28.0 mV, respectively. Under acidic conditions, the high concentration of H+ in the sludge system made it positively charged and changed PAC into Al3+. The polymer chains are attached to the surface of particle at several points by adsorption to unattached segments that extend into the bulk of the liquid; the chain may loop back and attach to the same particle and other particles, eventually linking particles together to form flocs [47–48].

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