Design and Verification of a Model Secondary Clarifier for Activated Sludge

Abstract

A model clarifier was designed using conventional methods for the surface calculation and an alternative pathway for the determination of the height and constructed accordingly. In addition, a new approach was used to evaluate the necessary scraper speed in comparison to full‐scale clarifiers. Scaling effects were taken into account. The model clarifier was first tested by tracer experiments. Conductivity measurements were used for the clarification zone, whereas the thickening zone was tested using pyrene as an organic tracer compound. Finally, the behaviour of the model clarifier was compared with a full‐scale settler. The results indicated that operation of the model clarifier was representative of full‐scale behaviour, except for severe overloads. Hence, the small‐scale clarifier qualified as a model for small‐scale studies and could be installed on large‐scale plants to monitor more transparently plant performance and sludge behaviour

Wastewater Treatment and Reclamation: A Review of Pulp and Paper Industry Practices and Opportunities

“…Although settling can be achieved in a simple unagitated "pond" or "stabilization basin" (Gehm 1973), it is generally preferred to employ a circular-shaped clarification basin, equipped with a slowly-rotating skimmer and raking device (Lugowski 1991;Grijspeerdt et al 1996;Albertson and Wilson 1997). The skimmer picks up foam and any lighter-than-water material that has floated to the surface.…”

“…The latter objective is typically achieved by agglomerating the particles together, noting that larger particles of the same general type generally settle more rapidly (Leitz 1993;Matko et al 1996;Fernandes et al 2014). Although settling can be achieved in a simple unagitated "pond" or "stabilization basin" (Gehm 1973), it is generally preferred to employ a circular-shaped clarification basin, equipped with a slowly-rotating skimmer and raking device (Lugowski 1991;Grijspeerdt et al 1996;Albertson and Wilson 1997). The skimmer picks up foam and any lighter-than-water material that has floated to the surface.…”