Is Your Settling Apparatus Good for Evaluating Secondary Clarifier Capacity?

摘要

State point analysis is a useful tool to evaluate the capacity of secondary clarifiers by predictingsolids transport between aeration tanks and clarifiers. Using existing empirical settling modelsbased on the functions of Sludge Volume Index (SVI) is a good starting point for designing orevaluating clarifiers. However, these models may not suit the specific situation of a particularwastewater treatment facility due to restricted data sets used for building these models .Developing the solids flux curve for the facility under evaluation is always desired. Beakers,settleometers and square beakers are good tools for qualitatively describing the settleability ofbiomass. They under-estimated the secondary clarifier capacity when they were used to developthe sludge settling curves. 1-L graduated cylinders with stirring and 4-L graduated cylinderswithout stirring generated similar limiting solids fluxes which were close to observed peak solidsfluxes at the plants, while 1-L graduated cylinder tests produced a wider operating range. Thesettling curves based on the 4-L graduated cylinder tests fitted the field operating data better atboth testing facilities. Therefore, 4-L graduated cylinders without stirring were recommended forwastewater treatment facilities to develop their own solids flux curves.