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Concentric well screen filter design
Offset filter bed design
55 gallon barrel filters around a shared clear wellGallon Barrel Filters with Shared Clear Well
Single 55 gallon barrel filter schematic
Height required to attain backwash velocity (with headloss calculations)

Factors to

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consider for operation:

1)a. Sand level monitoring
b. Pressure across filters
c. -Plexi-glass viewing strip on barrel side
2)Pressure across filters-when do the filters need to be back-washed?
-piezometer
3)Backwash Velocity- achieve bed expansion without losing sand
-Gate valve on siphon tube
4)Flow distribution during backwash
d. Bypass entire system-avoiding shocks to the system
5)Bypass -for seasons when filtration is unnecessary

Discussion topics

a. 7 backwash 1 problems/feasibility
b. Inclusion of clear well
c. Backwash with raw water

Future work

1)8 parallel filters: where 7 down-flow filters backwash 1 filter
-Problem: not flexible for variable plant flow rates
-If multiple filters are dirty, can not achieve desired backwash velocity
2)Clear well might be necessary
-Constant backwash velocity
-If multiple filters are dirty, filters can still be back-washed
3)Backwash from sedimentation tank
-Is using raw water for backwash okay?
-At end of backwash ~6 inches of dirty water is retained in bed, so the first distribution of water after backwash will have high turbidity

Future work

Bench top model:
-Test how changing the height difference (between the water level in the clear well to the bottom of the siphon) influences backwash velocities.
-Fine-tune the backwash velocity using a gate valve on the siphon tube.a. Bench top model