Effect of Salts on the Rate of Coagulation and the Optimum Precipitation of Alum Floc¹

Effect of Sulfate and Other Ions in Coagulation With Aluminum(iii)

“…Standard deviations of 0.088 and 0.057 for the nitrate and sulfate data, respectively, indicate good replication of experimental data, and suggest a significant difference between the two systems at this boundary. Apparently the simple equilibrium: Al(OH)a(s) + H20 = Al (OH)4-+ H+ (1) which described the aluminum nitrate results 8 does not fully explain the aluminum sulfate system. Figure 6 presents in an overlay a comparison of the marked similarities and differences between the aluminum sulfate and the aluminum nitrate stability domains for Escherichia coli.…”

“…erally recognized as a more effective coagulant than aluminum nitrate. As described by Peterson and Bartow, 1 and again by Black, Rice, and Bartow," sulfate has the effect of broadening the pH range of coagulation to the acid side. In a previous study, the present authors 8 investigated the coagulation of the Gram negative bacterium Escherichia coli by aluminum nitrate.…”

Floc Formation Studies in Water Purification

“…The different optimum pH values of coagulation, the variations in isoelectric points reported, and the conflicting opinions given by those attempting hydrogen-ion control, indicate that there are factors to consider other than pH alone. This inconsistency was studied by Peterson and Bartow (9) and Miller (6). They showed that coagulation may be retarded and confined within narrow limits by the anions present.…”

Coagulation of Soil Suspensions by Aluminum and Iron Salts Electrophoretic Study

“…Factors such as the effect of the quantity and type of electrolytes in turbid waters were not considered. Bartow (1), Black (2), and Peterson (10) found that sulfates as neutral salts present during the precipitation of iron and aluminum hydroxides shift the pH zone of rapid flocculation to the acid side. Theriault and Clark (12), Miller (9), and others found similar effects with other anions.…”