Separation units, hydraulic performance

Ovhemical DOSING for improvement of liquid-solid separation is traditionally designed and operated more or less independently of the geometry and hydraulic performance of the actual separation reactor. The widespread use of jar tests in the day-to-day operation of filtration and flotation plants illustrates this fact. Yet it is not difficult to visualize situations in which aggregation processes would furnish floes unsuitable for the subsequent separation unit, such as voluminous floes that do not settle out readily. 

Experimental Procedure. The investigations were performed in scaled-down continuous-flow reactors (with a scale of about 1 40 relative to the size of technical reactors for aggregation and separation. The hydraulic regime was closely controlled in both coagulation and separation units through exact temperature control (T = 20 0.2 °C) and the maintenance of a constant hydraulic throughput. Suspensions were coagulated in tube-type reactors. 

Quantitative description of the hydraulic performance of the separation units (both sedimentation and flotation tanks) was one major aim of this investigation. The flow structure, such as conditions of turbulence (microscopic... 

Gas flotation units normally include multiple cells in series. If the mechanical or hydraulic aeration imit in any cell fails, the water merely flows through that cell with little or no oil separation. As a result, mechanical failme in a single cell causes a degradation in performance. For example, a foru-cell unit with a mechanical failure in one cell becomes a three-cell unit capable of separating 87.5% of the dispersed oil in the feed stream (i.e., 1- (1 - 0.5p = 0.875). 

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