Page History

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This page describes the fundamental filter design used in our plant configurations. The single 55 gallon barrel design uses conventional down-flow sand filtration and uses a siphon and clear well to backwash.

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Our design was influenced by existing automatic backwash designs, however, this design employs a simpler geometry and is incorporates a recycled 55 gallon drum.

Image Added

Operation

1) Raw water enters 55 gallon drum and passes through sand filter.
2) Filtered water enters screen pipe and flows to clear well.
3) As filter clogs, head loss increases in region "A". This backpressure causes flow to be directed up siphon. Once the siphon fills backwash can be started.
4)Backwash begins when the operator opens both siphon valves and shuts off raw water inflow.
5)The column flow out of water in the siphon rises and eventually passes turn, where flow accelerates, creating creates a low pressure in region "A". The pressure differential between A and B induces backwash cycle top of barrel and flow from clear well expands sand bed and backwashes filter.
4 6) Siphon Backwash is broken by small pipe exposed to atmosphere, stopped by closing upper valve of siphon and remaining backwashed water goes to wastestays in column. At this point filter has been backwashed and continues operating as normal.

• Interface between sand and effluent pipe has not yet been determined. Possibilities include gravel or screen pipe, respective head losses under investigation

Image Removed; the siphon remains primed.