Journals Proceedings

Abstract

The aim of this paper was to establish a sizing safety decision boundary for a successful clarifier design and performance in an activated sludge wastewater treatment plant. The key objectives are to propose an alteration to the internal hydrodynamic characteristic of the final clarifier by determining the surface area and side wall depth of the clarifier using the WRC and ATV1991 design approach, and predict the clarification and thickening condition within the final clarifier using both the solid flux (pitman and white 1984 & Wahlberg and keinath 1998) and state point analysis. The methodology involved collecting site specific data from a wastewater treatment plant situated in the West Midlands, under different operating condition A to D and using a one dimensional mathematical model developed based on solid flux theory to analyse the results. The optimised sizing safety decision for final clarifier design and performance for site specific condition B ( 3.0kg/m³ MLSS, 110mg/l SSVI, 31.46 and eight final clarifiers) was 3.5kg/m³ MLSS, 80mg/l SSVI, 31.46 and six final clarifiers. This achieved a sustainable clarification and thickening efficiency. Clarifiers were under loaded and safe for operation with no indication of a solid washout. Significant savings in cost and footprint reduction was also achieved.