| Popis: |
1937, and again in 1938, Baylis1 presented data indicating that the turbidity test did not necessarily measure the quantity of floe passing through sand filter layers. This conclusion was based upon a study in which effluents from a series of sand filters having layers of varying thicknesses, were passed through cotton plugs at a constant rate and under a constant head for a period of from three to eight days. The plugs were burned and the ash weighed, and it was assumed "that the amount of suspended matter in a particular water is in proportion to the ash." Various coagulants were utilized in this study, among which were alum, iron and lime, Ferrisul, and combinations of these with silica. |
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