Page History

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1) Raw water enters 55 gallon drum and passes through sand filter.
2) Filtered water 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 flow out of the siphon creates a low pressure in top of barrel and flow from clear well expands sand bed and backwashes filter.
6)Backwash is stopped by closing upper valve of siphon and remaining backwashed water stays in column. At this point filter has been backwashed and continues operating as normal; the siphon remains primed.

Discussion

Our design combines the siphon with a conventional clear well and allows for a lower, smaller clear well, resulting in less waste during backwash cycle. The design uses recycled 55 gallon barrels and is an easily manufactured filter.