Qiu Shen's Individual Contribution Page

This Last semester I worked with foam filter preflocculation team. I We designed and build a bench-scale foam filter with tube flocculator. Together with my teammates we conducted over 40 tests and the conclusions are summarized below.

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A series of tests varying foam depth with and without flocculator were ran to further explore the filtration theory of the foam filter. We have observed that the first layer of foam (10 cm depth) works well as a flocculator. We assume that the headloss is an indicator of the sufficiency of flocculation. Without preflocculation, foam functions as both flocculator and filter. While headloss increase increases over time as a result of mass accumulation, Gin foam filter increase and flocculation became more sufficient and , thus flocs grew bigger. As bigger flocs can be captured easier by the foam, pC* increase increases with time until the foam reached its loading capacity.

The tests varying foam depth also reveals reveal a good linear relationship between runtime and foam depth. The interception is -1.3 cm, which x-axis interception is theoretically the minimum length for the foam to function with pC*>1.  Foam depth only improves pC* up to around 30 cm of foam depth, which means flocculation mainly happens in the first 30 cm of foam. They function as both flocculator and  filter, and the flocculation and filtration process influence each other in every run. The rest of foam mainly functions as filters. The loading capacity of foam with flocculator is larger than that without flocculator. We think when the flocs are smaller, larger depth of clean foam is needed to remove them. So it weakened the loading capacity of foam.

When comparing foam filter with StaRS sand filter, the foam filter ran longer than the sand filter at similar flow rate, and the solid loading capacity of foam is greater than sand. But sand filter have higher pC*. We also found that the runtime and loading capacity of foam filter in at a low flow rate is much longer than that in at a high flow rate. This could be due to less shear exerted on the pores than at higher velocities. This suggests that if possible, a lower approach velocity will increase runtime leading to can lead to a better performance of the filter in real world application.

This semester I am working with High rate UASB team.