55 Gallon Barrel Filters with Shared Clear Well

Inspiration

The design improves upon the offset filter bed design by incorporating 55 gallon barrels. This simplifies manufacture of filters and construction of plant.

Design summary

• The plant has four filter groups (each filter group contains 4 55 gallon barrels)arranged around a shared clear well. Each filter group of four barrels has a intake manifold to distribute raw water in and an outlet siphon manifold used during backwash.

• The operating principles are identical to the offset filter bed with the exception of the siphon. We studied siphons in more detail and determined that we need a submerged end for proper function. The siphon has two valves: one at the lowest point of the pipe to prime an initially empty siphon, and a second at the highest point of the siphon. This upper valve is used to initiate the backwash cycle.

• A valve was placed in the influent pipe to turn off flow during backwash cycle. Shutting off the inflow is crucial to develop a sufficient pressure gradient to backwash.

Discussion

This is our most up to date design. The addition of valves provides more control of the system and makes optimizes the siphon. The clear well and siphon in conjunction provide sufficient backwash velocity and have allowed us to significantly reduce the clear well height and volume. The filters still lack a simple way to observe the sand levels and measure pressure drop.