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Current Research
Bench Scale Model Design
To test the theory behind the stacked rapid sand filter, a bench scale model was designed and built. Using this model, a series of experiments will be conducted to test the filtering capacity of a stacked rapid sand filter.
This is our current experimental apparatus.
Backwash
We need to prove Back Wash
The most important challenge to prove is the ability to clean the stacked rapid sand filter by the back wash methodbackwashing. In order to back wash the filter, we must prove that the individual filter layers can be fluidized in sequence, and thus result in a fully fluidized filter. Once fully fluidized, the filter can then be back washed, and require significantly less water than a comparable conventional single layer filterprove backwashing works, we need to fully fluidize the filter and settle it to continue filtration.
Performance Comparison
In order to learn if the flow distribution in the stacked rapid sand filter system is working reasonably well, it is necessary to conduct an experimental comparison to a conventional single layer filter of the same depth as a single layer of our stacked filter (20 cm).
Head Loss Measurement
The head loss across the filter over time is the governing factor that determines the effective filtration cycle time. The build up of head loss ultimately determines how often the filtration unit will require back washingbackwashing.
Future Research
Filtration Unit Design
It is necessary to design a filtration unit that can be built at our existing water treatment plants , and be incorporated into future plant designs. This includes a hydraulic analysis to calculate the critical elevations for in relation to how the filter fits in with the sedimentation tank effluent weir and the distribution tank. This analysis must be done using the approach for the design tool with correctly named variables, and with the standard inputs of flow rate and then automated design of the filter system. This automated design must include full hydraulic design of all of the piping required.
Performance Study
A number of parameters will need to be studied in order to find the optimal design conditions for a filtration unit. The variables to be studied experimentally include diameter of sand grains, depth of each filter layer, horizontal spacing between pipes, and filtration velocity. A robust study of all these variables will require a long period of time, and it is thus recommended that we proceed with the design and installation of a filtration unit with conservative design parameters. Once full-scale performance can be analyzed, we can proceed with an exhaustive performance study to further optimize the stacked rapid sand filtration unit design.
Future Research
Field Scale Testing
We plan to build a stack rapid sand filter as an addition to an existing plant that uses AguaClara technology.
Past Research
Summer 2010 SRSF Research
Built initial bench scale model and initialized proof of concept.
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