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The goal of our research is to evaluate the feasibility of a siphon-aided backwash design to be used for a sand or mixed-media down-flow filter. The benefits of siphon-aided backwash are:
1) The height of the clear-well does not need to be equal to the the head pressure required to attain 30%-50% expansion.
2) The siphon tube is designed to fill up when the filters have reached a terminal headloss (a set point we determine). Thus, they only backwash when they are dirty.
3) Since the headloss energy is used to prime the siphon, and eventually trigger backwash, fewer valves are required which reduces cost and laborfilter bed can be right next to the clear-well, connected via an open pipe without a valve. Flow of water into and out of the clear-well will be controlled by valves on the influent and backwash manifolds.
3) Using 55 gallon HDPE barrels, we will create a system of parallel filters surrounding a shared clear-well. By backwashing the filters out of phase, we will reduce the demand for a large clear-well. Additionally, the downflow filters will be filling the clear-well while the other filters being backwashed draw from it. This allows faster clear-well recharge rates and shortens the time between consecutive backwash cycles.

The inspiration for our design

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