Effect of polyvalent metal ions on the rate of decomposition of cellulose xanthate in the precipitation bath

1984 ◽  
Vol 15 (3) ◽  
pp. 212-213
Author(s):  
N. A. Mazur ◽  
K. A. Malyshevskaya ◽  
T. N. Verkhoturova
Keyword(s):  
Metal Ions ◽  
Cellulose Xanthate ◽  
Precipitation Bath ◽  
Polyvalent Metal

Study of Flocculation Mechanisms by Observing Effects of a Complexing Agent on Activated Sludge Properties

1991 ◽  
Vol 24 (7) ◽  
pp. 21-28 ◽  
Author(s):  
L. Eriksson ◽  
B. Alm
Keyword(s):  
Activated Sludge ◽  
Metal Ions ◽  
Electrostatic Interactions ◽  
Wastewater Treatment Plants ◽  
Sedimentation Velocity ◽  
Complexing Agent ◽  
Extracellular Polymers ◽  
Filtration Resistance ◽  
Polyvalent Metal ◽  
Sludge Properties

Electrostatic interactions between bacterial surfaces, extracellular polymers (ECP) and polyvalent metal ions are important in activated sludge flocculation. An indirect study of these mechanisms was done by adding different concentrations of EDTA to activated sludge samples from 6 Swedish wastewater treatment plants. The effects on sludge properties were studied with sedimentation and filtration tests as well as analysis of released extracellular polymers. EDTA had a significant effect on sedimentation velocity in all investigated sludges. This shows that charged polymers are important for the properties of the floc surfaces and in building up the sludge macroflocs. The effect on filtration resistance where the bulk properties of the primary flocs are more important varied considerably for the different sludges. Thus, both electrostatic and other interactions are involved to a varying extent in building up the primary flocs in the sludges investigated. Variations in sedimentation velocity, residual turbidity, filtration resistance and release of ECP with variations in EDTA concentrations could be explained by effects of polyvalent metal ions on ECP binding and conformation.

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