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During Fall 2010 I have continued working on the Stacked Rapid Sand Filtration Team. In order to wrap up the summer proof-of-concept research, we made as a team have made systematic physical observations of the filter backwashing process in the clear filter column. We visually observed the backwashing process in the filter both to confirm that the bed of a stacked filter could effectively be fluidized, and to develop a procedure for initializing and terminating the process. The backwashing steps were varied and observation was the observations were used to determine which method of backwash backwashing was most effective. We are close to finishing up a proof-of-concept paper explaining the concept of stacked rapid sand filtration, using the summer performance data and this semster's backwash observations, to show that the technology is viable at the laboratory scale and to help put the technology out there. We have been running time-series and steady-state flow distribution tracer dye studies to determine whether flow in each layer of the filter is in fact uniform. These studies could show help us determine how much of the sand bed is effectively being used. Other things we've We have also been working on include: developing a full-scale filter design tool, applying to the EPA P3 sustainable design competition to fund future developments, and determining whether an underdrain system may be needed for the bench-scale stacked filter system.
In the near future we plan to: build a 20 cm single layer control filter in order to compare upflow from downflow filtration performance, run filter performance studies similar to those that took place during the summer so as to better understand inconsistencies observed during the summer occurances such as turbidity "spikes", and The size of the sand media will be important to filter sizing, head loss, backwash velocity, and overall performance. Also, sand uniformity will be a special concern in stacked filters. After the filter is fluidized during backwashing, the settling of coarser particles at the bottom of the sand bed may affect both the flow distribution in the filter and the turbidity removal. spikes that were observed during the summer, and possibly optimize the sand grain size of the filter media.