Stacked Rapid Sand Filtration Theory
The overarching goal of the Stacked Rapid Sand Filter Theory team is to develop a model for filter performance. A new apparatus will be designed to model a stacked rapid sand filter. Experiments with constant turbidity and varying coagulant dosages will be run and analyzed. From the analyzed data we hope to be able to create a model that will be able to predict the expected head loss of a given SRSF filter if the coagulant dosage and amount of solids already accumulated in the filter are known.
Overview
| Excerpt |
|---|
Spring 2013 (formerly called Depth vs. Surface Sand Filtration)
The big goal of this research is to understand the difference between surface and depth filtration and the parameters that determine which regime is operative. We suspect that subsurface injection of the water to be filtered shifts the regime to depth filtration. The head loss and effluent turbidity were measured and compared between a control filter, where water is added above the filter in a conventional downflow design, and a subsurface injection filter in which water is injected into the middle of sand bed through a smaller tube modelling a slotted pipe in the Stacked Rapid Sand Filter.
...
Depth
...
Depth filtration likely occurs when the fluid forces on the flocs that bridge across a pore in the filter bed exceed the strength of the flocs. Thus the dimensionless parameter that determines whether depth or surface filtration occurs must include both floc strength and pressure drop through a thin layer of flocs. Pressure drop through a thin layer of flocs is influenced by the porosity of the flocs which is a function of their fractal dimension. Small flocs are less porous than large flocs and thus small flocs are less likely to produce surface filtration.
...
Tasks for this summer involve finding the parameters at which the subsurface injection filter becomes clogged. Using the experimental apparatus built last semester, the team will continue research comparing the surface and subsurface sand filters. The team will run experiments and change the influent turbidity, influent velocity, and coagulant dosage. Effects on head loss and effluent turbidity will be observed and analyzed.
Fall 2013
The SRSF Theory will build a new filter column and run experiments testing filter performance.
| Section | |||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
...